GEOLOGICAL SURVEY OF PENNSYLVANIA.
FINAL REPORT ORDERED BY LEGISLATURE, 189L
A
SUMMARY DESCRIPTION
OF THE
GEOLOGY OF PENNSYLVANIA,
IN THREE VOLUMES,
A NEW GEOLOGICAL MAP OF THE STATE,
A MAP AND LIST OF BITUMINOUS MINES,
And many Page Plate Illustrations.
By J. P. LESLEY, State Geologist.
VOL. I.
DESCRIBING THE
LAURENTIAN, HURONIAN, CAMBRIAN AND LOWER SILURIAN
FORMATIONS.
HARRIS BURG:
PUBLISHED BY THE BOARD OF COMMISSIONERS
FOR THE GEOLOGICAL SURVEY.
BOARD OF COMMISSIONERS.
His Excellency ROBERT E. PATTISON, Governor,
and cf-officio President of the Board, Harrisburg.
ARIO PARDEE, Hazleton.
WILLIAM A. INGHAM, Philadelphia.
HENRY S. ECKERT, Reading.
HENRY McCoRMiCK, Harrisburg.
CHARLES A. MINER, Wilkes-Barre.
JOSEPH WILLCOX, Philadelphia.
Louis W. HALL, Harrisburg.
SAMUEL Q. BROWN, Pleasantville.
CHARLES H. NOYES, Warren.
W. W. H. DAVIS, Doylestown.
SECRETARY OF THE BOARD.
WILLIAM A. INGHAM, . . Philadelphia.
STATE GEOLOGIST.
PETER LESLEY, Philadelphia.
Entered for the Commonwealth of Pennsylvania, in the year 1892, according to acts of
Congress,
By WILLIAM H. INGHAM.
Secretary of the Board of Commissioners of the Geological Sun-rii.
In the office of the Librarian of Congress, at
WASHINGTON. D. C.
UNIVERSITY OF CALIFORNIA
> f SANTA BARBARA
Ptl
in I
LETTER OF TRANSMITTAL.
To His Excellency Governor ROBERT E. PATTISON, Ex-
officio Chairman of the Board of Commissioners of the
Geological Survey of Pennsylvania :
SIR : I have the honor to submit to your approval this
First Volume of the Final Report ordered by act of Legis-
lature, approved in June, 1891 ; being a Summary of the
results of the Survey from its beginning in June 1874 to
the close of its field work, June 1, 1890 ; since which date
office work has been continued for the completion of its
publications ; chiefly the last sheets of the Anthracite sur-
vey, the maps and sections of the survey of the New Red
belt of Bucks and Montgomery counties, the completion of
the Bituminous colliery map of Western Pennsylvania,
and a new Geological State Map. These will be published
in the coming summer, together with the Second and Third
volumes of this Final Report.
In writing this Summary I have quoted from more than
a hundred volumes of reports published by the Board
since 1875, a complete list of which, with an Index to their
subjects, will be found at the close of the third volume.
In every case I have given credit to and thrown respon-
sibility upon the assistant geologist who made the obser-
vation, or reported the fact quoted, by a reference in text
or foot note to date and page of his report.
Most of the illustrations are photo-electrotype reduc-
tions, and therefore fac-similes of the drawings made by
the assistant geologists, or in the office of the Survey
from their sketches, or from data in the text of their re-
ports, published in their reports during the course of the
Survey.
The smaller illustrations are grouped on page plates to
iv GEOLOGICAL SURVEY OF PENNSYLVANIA.
diminish the cost of the publication and to hasten its com-
pletion. They form in fact an illustrated index to the
maps and sections to be found (on a larger scale) in the
series of reports.
The names and districts of all the assistants on the sur-
vey will be found in a list at the end of the third volume.
I have endeavored to confine the text of the book to
general and systematic statements; and have therefore
placed all the detailed local and ancillary matter in foot
notes. I trust that this will accommodate the reader as
much as it has lessened the size of the book.
I have written it also in Saxon English, as far as a
work of physical science can be so written, as it is in-
tended for the use of the people of Pennsylvania, in whose
vocabulary Norman English has never been domesticated,
who greatly prefer before and after, or before and behind,
to anterior and posterior, and overlaid and underlaid to
superimposed and subjacent, as I do myself, and who are
mostly or wholly ignorant of Latin and Greek.
Although the personal element can never be entirely
suppressed from any work of man, I have endeavored to
avoid dogmatic statements not made by a consensus of
the geological opinion of to-day, and to place the many
differences of that opinion still remaining unsolved in
such a light as to show that our science is not an oligarchy
but a democratic republic, in which every voice has a right
to be heard, and that even after the vote has been taken
there remains the right of calling for a re-consideration
of it.
The book is almost wholly a practical description of facts
discovered or verified by the observation of the members
of the corps of the Geological Survey in their several dis-
tricts, not at all influenced by geological theories, but sim-
ply seen and measured, and placed in their true relations
to one another.
The arrangement of the book will be seen by consulting
the Table of Contents. The order of description is chrono-
logical from oldest to newest, but the representation of
of each formation is made as in a columnar section from
LETTER OF TRANSMITTAL. V
the top to the bottom, by which the mental conception of
the pile of strata is enforced by the eye. A descriptive
section with the bottom bed on top is an old-fashioned
abomination repudiated now by all good geologists.
The page plates of fossils, placed in all cases at the end
of the chapters of the several formations, are half -sized re-
productions of the figures of fossils given in Report P4,
Dictionary of the Fossils of Pennsylvania and the sur-
rounding States, published in 3 volumes in 1889-1890.*
The Dictionary has been so successful that the demand
for it has long since outrun the edition ; and the office of
the survey is in receipt of requests for it which cannot be
answered because the edition is exhausted. It has been a
completely successful experiment. But there has been a
call for the classification of the figures under the head of the
formations to which the fossils properly belong, and I have
endeavored to meet this call by grouping the figures of each
formation in a series of page plates, which will sufficiently
index the Dictionary for geological purposes.
In the case of each series the grouping begins with plants,
and proceeding upward in the order of life through species
of bryozoa and corals, brachiopod, gasteropod, cephalopod,
phyllopod and lamillibranch shells, annelids, crustaceans,
insects, and vertebrate fish and reptiles, so far as the for-
mation in question contains these. Where references to
authority and locality are wanting the reader must consult
the Dictionary. These page plates are for popular instruc-
tion and not for the use of experts.
J. P. LESLEY,
1008 CLINTON STRBET, PHILADELPHIA,
February IS, 1892.
* P4, Vol. 4, Appendix, was forbidden by the Board to be published until
after the final report and other publications of the survey had been printed,
for fear of delaying these. In consequence of this action, I have been pre-
cluded from inserting in these page plates many of the fossil forms found in
Pennsylvania and elsewhere recently, many of them of the most inter-
esting character.
VOL. I.
TABLE OF CONTENTS.
I. Our Geological Knowledge, 1
II. Geological Time, how measured, ... . 5
III. Geological Dimension; area, outcrop, dip,
thickness, 22
IV. General sections; typical sections; local
sections; columnar sections, .... 30
V. The Appalachian sea, 35
VI. The Names of the Formations, 39
VII. Archaean, Azoic, Highland, Laurentian, Fun-
damental gneiss, Crystalline schists, . 53
VIII. Archaean Highland Belt in Pa. and N. J , 63
Archaean Types in New Jersey, .... 71
IX. Archaean rocks of Pa., Reading and Dur-
ham hills, 74
In northern Chester county, 75
In Bucks, Montgomery and Delaware
counties, 79
On the Schuylkill river, 91
X. Are the Archaean rocks sedimentary ? . . 95
The argument from Olivine, 98
The argument from Serpentine, .... 101
Delaware Co. serpentines, 102
Chester Co. serpentines, 103
Lancaster Co. serpentines, 104
Northampton Co. serpentines, .... 105
The argument from Labradorite, . . . 107
The argument from Marble, 109
The argument from Apatite, 113
The argument from Iron ore, 115
viii GEOLOGICAL SURVEY OF PENNSYLVANIA.
Chapter. Page>
XL The Newer Gneiss of the Philadelphia belt, 118
Its three sub-divisions, 120
1. The Philadelphia(lower) sub-division, 121
2. The Manayunk (middle) sub-division, 122
3. The Chestnut Hill(upper)sub-division, 123
The Chestnut Hill fault, 125
XII. The Philadelphia rocks in Chester, Lancas-
ter and York counties, 127
The Newer Gneiss in York county, . . 128
The Newer gneisses in Maryland, . . . 130
XIII. Hydro-mica slate formation; phyllite belts
of York and Lancaster counties ; South
Valley Hill slate of Chester Co., . . 133
Main York Co. phyllite belt 134
Southern or Peach Bottom belt, ... 136
Peach Bottom roofing slates, 137
XIV. Geology of the South Mountains, .... 142
XV. The Huronian System, so called, 152
XVI. For. No. I, Chiques sandstone, Hellam
quartzite, North Valley Hill sandstone
of Chester Co., Potsdam sandstone,
Upper Cambrian quartzite, Sugar Loaf
sandstone of Md., 165
No. I on the Susquehanna, 168
The Chiques Ridge fault, 171
No. I, east of the Lancaster plain, . . . 173
Rogers' Primal in the Chester Valley, . 175
No. I in the Highland range, 179
No. I in Southern Chester Co., . . . 181
No. I in Southern York Co., 182
No. I in the Pigeon Hill, 182
No. I along the South Mountains, ... 183
No. I in Middle Pennsylvania, .... 186
XVII. On Scolithus linearis, 187
XVIII. On Cambrian fossil life, . . 192
XIX. South Valley Hill slate belt, 199
XX. Iron mines in the Primal Upper Slate, . . 205
York county limonite banks, 211
TABLE OF CONTENTS. IX
Chapter. Page.
Banks north of York, 214
Banks west of York, 215
Banks of the Pigeon Hills, 216
Banks near Hanover, 217
Banks south of the York Valley lime-
stone, 219
Banks in the York Co. phyllite belt. . 220
Banks in the hydromica belt S. of York, 222
Adams county limonite banks, . . 225
Lancaster county limonite banks, . . . 226
Welsh Mountain banks, 228
Northampton county limonite mines, . 229
Ranges of Northampton banks, . . . . 231
Lehigh county limonite mines, .... 233
Berks county limonite mines 235
In Oley valley, 236
Cumberland county limonite mines, . . 238
Mountain Creek limonite banks, . . . 241
Banks along Yellow Breeches creek, . 246
Franklin county limonite banks, . . . 248
Mont Alto bank, 249
Path Valley mines, 252
The two Virginia ranges, 253
Grubb'sCodorus ore in quartzite, . . . 253
Lehigh Mtn. Min. Co.'s mine, .... 254
XXI. Magnetic limonite mines doubtfully re-
ferred to the Primal slates, or to the
Gneiss, or to the Trias, in York, Ches-
ter and Berks counties, 256
In York county, 256
In Chester county, 262
The Warwick group 265
In Berks county, 267
XXII. On the Great Valley, 270
Levels above tide of water ways, . . . 271
The two belts, limestone and slate, . . 274
Synclinal mountains of IV in III, . 278
Anticlinal belts of II in III, 279
viii GEOLOGICAL SURVEY OF PENNSYLVANIA.
Chapter. Page>
XI. The Newer Gneiss of the Philadelphia belt, 118
Its three sub-divisions, 120
1. The Philadeiphia(lower) sub-division, 121
2. The Manayunk (middle) sub-division, 122
3. The Chestnut Hill(upper)sub-division, 123
The Chestnut Hill fault, 125
XII. The Philadelphia rocks in Chester, Lancas-
ter and York counties, 127
The Newer Gneiss in York county, . . 128
The Newer gneisses in Maryland, . . . 130
XIII. Hydro-mica slate formation; phyllite belts
of York and Lancaster counties ; South
Valley Hill slate of Chester Co., . . 133
Main York Co. phyllite belt, 134
Southern or Peach Bottom belt, ... 136
Peach Bottom roofing slates, 137
XIV. Geology of the South Mountains, .... 142
XV. The Huronian System, so called, 152
XVI. For. No. I, Chiques sandstone, Hellam
quartzite, North Valley Hill sandstone
of Chester Co., Potsdam sandstone,
Upper Cambrian quartzite, Sugar Loaf
sandstone of Md., 165
No. I on the Susquehanna, 168
The Chiques Ridge fault, 171
No. I, east of the Lancaster plain, . . . 173
Rogers' Primal in the Chester Valley, . 175
No. I in the Highland range, 179
No. I in Southern Chester Co., . . . 181
No. I in Southern York Co., 182
No. I in the Pigeon Hill, 182
No. I along the South Mountains, ... 183
No. I in Middle Pennsylvania, .... 186
XVII. On Scolithus linearis, 187
XVIII. On Cambrian fossil life, . . 192
XIX. South Valley Hill slate belt, ..... 199
XX. Iron mines in the Primal Upper Slate, . . 205
York county limonite banks, .... 211
TABLE OF CONTENTS. IX
Chapter. Page.
Banks north of York, 214
Banks west of York, 215
Banks of the Pigeon Hills, 216
Banks near Hanover, 217
Banks south of the York Valley lime-
stone, 219
Banks in the York Co. phyllite belt. . 220
Banks in the hydromica belt S. of York, 222
Adams county limonite banks, . . 225
Lancaster county limonite banks, . . . 226
Welsh Mountain banks, 228
Northampton county limonite mines, . 229
Ranges of Northampton banks, .... 231
Lehigh county limonite mines, .... 233
Berks county limonite mines, .... 235
In Oley valley, 236
Cumberland county limonite mines, . . 238
Mountain Creek limonite banks, . . . 241
Banks along Yellow Breeches creek, . 246
Franklin county limonite banks, . . . 248
Mont Alto bank, 249
Path Valley mines, 252
The two Virginia ranges, 253
Grubb'sCodorus ore in quartzite, . . . 253
Lehigh Mtn. Min. Co.'s mine, .... 254
XXI. Magnetic limonite mines doubtfully re-
ferred to the Primal slates, or to the
Gneiss, or to the Trias, in York, Ches-
ter and Berks counties, 256
In York county, 256
In Chester county, 262
The Warwick group 265
In Berks county, 267
XXII. On the Great Valley, 270
Levels above tide of water ways, . . . 271
The two belts, limestone and slate, . . 274
Synclinal mountains of IV in III, . 278
Anticlinal belts of II in III, 279
GEOLOGICAL SURVEY OF PENNSYLVANIA.
Page.
Limestone coves in the slate belt edge, 283
Synclinal belts of III in II, 286
Southern edge of No. II, 289
Relation of South Mts. uplift toll, . . 291
XXIII. Why is there no coal in the Great Valley ? 294
XXIV. No. II. The Great Valley limestone, ... 298
Sub-division of No. II, 299
XXV. No. II in the Lehigh region, 301
The folded stratification, 306
XXVI. Limestone quarries of the Great Valley be-
tween the Schuylkill and Snsque-
hanua rivers, 309
Berks county quarries, 311
Lebanon county quarries, 314
Lebanon city group, 315
Annville group, 317
Dauphin county quarries, 319
Swatara quarries, 319
Hummelstown group, 320
Beaver station group, 321
Paxtang group, 322
XXVII. Limestone quarries of the Great Valley in
Cumberland and Franklin, 324
XXVIII. MagnesianbedsinNo.il, 327
Section of beds opposite -Harrisburg, . 331
Negative deductions from facts, . . . 334
Amount of magnesia present, .... 334
XXIX. Hydraulic cement quarries on the Lehigh, 337
In Mifflin and Centre counties 340
XXX. Limonite mines near the top of II, . . . . 341
Ironton and other mines in Lehigh Co., 345
Moselem mine in Berks Co., 350
Cornwall mine in Lebanon Co., .... 351
Path Valley mines in Franklin Co.. . . 357
Henrietta mines in Blair Co., 361
XXXI. No. II. Nittany Valley limestones, ... 365
Centre county anticlinals, ...... 365
Centre county cross sections, 369
TABLE OF CONTENTS. XI
Chapter. Page.
XXXII. Centre Co. limonite mines, 372
Two varieties of ore, 372
Pennsylvania Furnace mine, 378
XXXIII. Nittany Valley, Huntingdon county, mines, 387
Pennington range, 390
Warrior Mark and Lovetown range, . . 391
Dry Hollow range in Huntingdon Co., . 391
Cale Hollow range in Huntingdon Co., 394
Huntingdon furnace banks, 398
Sinking Valley mines, 399
XXXIV. Canoe Valley and Morrison's Cove, ... 401
The Springfield mines 404
Leathercracker Cove ores, 409
Morrison Cove ores ; Bloomfield mine, . 414
XXXV. Friends Cove 419
Milliken'sCove, 420
Kishicoquillis Valley, 421
Black Log Valley, 422
McConnellsburg Cove, 423
Horse valley, 424
XXXVI. Caverns and Sinkholes in II, 425
Rate of erosion of II, 430
Precipitation of limonite in caves, . . . 433
Depths of limonite deposits in caves, . 434
Precipitation from pyrites, 435
XXXVII. Zinc, Lead and Barium in No. II 436
Saucon zinc mines in Lehigh Co., . . . 436
Bamford zinc mines in Lancaster, ... 44
Sinking Valley zinc mines in Blair, . . 444
Barytes in No. II, 447
Gypsum absent from No. II, 450
XXXVIII. Trap Dykes in No. II, 451
Grand Horseshoe Dyke in Perry, . . . 458
Little Horseshoe Dyke, 460
Mid Cove Dyke, 460
Duncannon Dyke. 461
Effects of trap, 464
Serpentine in No. II 464
Xii GEOLOGICAL SURVEY OF PENNSYLVANIA.
Page.
XXXIX. White limestone and marble of II, ... 467
In New Jersey, 469
In York county, 473
In Chester county valley, 477
In Centre county, . 479
XL. Black marble in No. He., 482
XLI. Thickness of formation No. II, 485
In Lancaster county, 485
In Middle Pennsylvania, 488
In New York'State, 489
XLII. Oil and Gas in No. II, 492
Why no Trenton oil or gas in Pennsyl-
vania, 494
XLIII. Mechanical deposits of No. II, 497
A peculiar sandstone, 497
Parkesburg artesian well, 498
XLIV. The Fossils of No. II, 501
Fossils of the Calciferous, Ha, . . . 511
Fossils of the Quebec group, 511
Fossils of the Chazy, lib, 513
Fossils of the Black River, He., . . . 513
Fossils of the Birdseye, He. 515
Fossils of the Trenton, He, 517
XLV. No. Ill, Utica and Hudson River forma-
tions, 525
The Sea in which the Deposits were made, 529
Nonconformability, 531
Origin of the pyrites, ........ 537
Fossil abundance 538
Fish discovered under Trenton, .... 541
Black slates 542
Limestone intercalations, 543
The roofing slate belt, 543
Stratification and foliation of slate, . . 547
Rolls in the slate, 550
Thickness of the formation, 551
Peach Bottom roofing slate, 555
XLVI. Thickness of No. Ill, .... .557
TABLE OF CONTENTS. xitt
Chapter. Page.
XLVII. Character of No. Ill, 562
Fossils in the formation, 565
Quartz veins ; their origin, 566
Flagstone layers, 569
Mineralogical poverty of III, . ". . . . 570
Neither oil nor gas in III, 571
Iron ore in III in New York, 572
XLVIII. The Roofing Slate Beds of No. Ill, ... 574
Westward extension of the belt, . . . 589
Notes on the Bangor belt by R. M, Jones, 582
XLIX. The slate quarries in 1882, 588
In Northampton Co., Washington town-
ship, 590
Lower Mt. Bethel township, 592
Plainfield township, 593
Bushkill township, 595
Upper Nazareth and Moore, 596
East Allen township, 599
Allen and Lehigh townships, 600
In Lehigh Co., Washington township, . . 604
N. Whitehall and Heidelburg, .... 608
S. Whitehall and Lynn, 607
In Berks Co., Albany township, 609
Weisenburg and Albany, 611
In Perry township, 615
L. Fossils of No. Ill, 617
Peach Bottom fossils for comparison, . 618
LI. No. IV. Oneida and Medina formations, 625
Thickness of No. IV., 627
At the gap above Harrisburg, 637
Comparative tables in the gaps, .... 641
Thins southward and northward, . . . 649
No. IV described in Logan gap, . . . 651
No. IV at Orbisonia, 653
No. IV in Spruce Creek gap, 655
No. IV in Tyrone gap : section, .... 657
No. IV in Mill Hall gap, 659
No. IV, in Williamsbnrg gap, .... 661
GEOLOGICAL SURVEY OF PENNSYLVANIA.
Page.
No. IV in the Bedford gaps, 661
Oneida, IVa, not deposited there, ... 663
No. IV in Clinton, Centre, Lycoming, . 667
No. IV along the Great Valley, .... 669
No. IV at the Susquehanna Water Gap, 669
No. IV at the Schuylkill Water Gap, . 673
No. IV at the Lehigh Water Gap, . - 674
No. IV at the Delaware Water Gap, . 675
No. IV in New Jersey, 676
No. IV in New York, 677
Lead ore veins in No. IV, 678
LII. Topographical features of No. IV, .... 681
Three groups of mountains of IV, . . 682
Parallelism of mountains of IV, ... 686
Convergence of mountains of IV, . . . 688
Mountain spurs of FF, ....... 689
Anticlinal and synclinal knobs, .... 692
Crests, single and double, 695
Difference in heights, 696
Keel mountains of IV, 697
Oneida Terrace, ravine system, .... 698
Anticlinal vaults restored, ...... 699
Model of the plications of Middle Penn-
sylvania, representing the upper sur-
face of Medina, IVc., 703
Methods of constructing a model, . . . 704
Conformity of IV upon III, ..... 707
LIU. The mineral worthlessness of the mountains
of IV, 711
Foot notes on gold, silver, etc., .... 712
LIV. The fossils of No. IV, 714
May Hill sandstone in England, . . . 716
The earliest echinus, cockroach, 'fern, . 716
Lesquereux's L. Silurian land-plants, . 717
Drifted plants show changes of the rela-
tions of land to sea, and changes of
vegetation on land, 718
VOLUME I.
LIST OF ILLUSTRATIONS.
276 (PI. I). Map of the bends of the Conedoguinit creek
in Cumberland Co., to show their relation to the out-
crop contact line of II and III.
277 (II). Cross section of the Great Valley on the meridian
of Harrisburg, to illustrate Chapter 22.
280 (III). Map of the Great Valley west of Carlisle, to show
the coves of II in the outcrop edge of III.
281 (IV). Cross section of the Great Valley, to show the
hypothetical character of the Path Valley faults.
284 (V). Pig. 1, Exposure of waves in beds of II; Fig.
2, Local map of a limestone cove of II in III near
Orrstown, Cumb. Co.
285 (VI). Fig. 1, Cross section of the Hole, at Swataragap;
Fig. 2, A similar cross section of Path Valley and
Bear Valley at Loudon, Franklin Co. ; Fig. 3, Map
of southern Franklin, showing the parallel zigzag
outcrops of No. IV, the parellel alterations of III
and II at Mercersburg, and the crenulated edge of
the limestone belt.
331 (VII). Vertical detailed section of 115 limestone beds
in the McCormick quarries opposite Harrisburg. with
thickness, and the percentage of carbonate of mag-
nesia designated by tint.
348 (VIII). Figs. 1, 2, Maps of Moselem limonite mine and
vicinity, Berks Co. Fig. 3, map of the Lebanon city
and Cornwall part of the Great Valley.
349 (IX). Figs. 1, 2, 3, Cornwall mine cross sections.
352 (X). E. V. d'Invilliers' map of Cornwall mine.
353 (XI). Nine illustrations of the Cornwall mine.
XViii GEOLOGICAL SURVEY OF PENNSYLVANIA.
616 (LXX). Fossil seaweeds of Peach Bottom slate. P.
Frazer.
618 (LXXI). Others drawn by J. P. Lesley.
622 (LXXII). Photograph of Jack's mountain anticlinal
arch.
624 (LXXIII). (1) Seven Mtns., 6 cross sections.
Sketch map of mountains of IV from Bald Eagle
across to Tuscarora mountains.. (3) Views, map and
cross section of an eddy hill in Big Fishing Creek
Gap in Centre county.
626 (LXXIV). (1) Bald Eagle (Bellefonte) gap, contour
map. (1) Canoe Valley narrows of the Juniata, Hunt-
ingdon Co. (3) Map of zigzags of IV in Perry Co.
628 (LXXV). Greenwood Furnace fault ; two sections, and
a map.
630 (LXXVI). Bald Eagle faults. Map by E. B. Harden.
632 (LXX VII). Port Clinton gap section. H. M. Chance.
634 (LXXVIII). Delaware gap section. H. M. Chance.
636 (LXXIX). Lehigh gap contour map, by H. M. Chance.
638 (LXXX). Delaware gap section. H. M. Chance.
640 (LXXXI). Logan gap section, Mifflin Co.
642 (LXXXII). Lewistown section, Mifflin Co.
644 (LXXXIII). McVeytown section, Mifflin Co.
646 (LXXXIV). Long Hollow section, Mifflin Co.
648 (LXXXV). (1) Kishicoquillis valley section. (2) Mc-
Kee mine section. (3) Mount Union section.
650 (LXXX VI). Orbisonia section No. 1, Huntingdon Co.
652 (LXXXVII). Orbisonia section, No. 2.
654 (LXXX VIII). Delaware Water Gap contour map.
656 (LXXXIX). (1) Jack' smtn. anticlinal crest section, to
show its sudden decline in Huntingdon Co. (2) Map
of the same. (3) Port Clinton map, showing fault
at the Schuylkill. (4) Warp of dips, E. and W.
side of Delaware Water Gaps.
658 (XC). (1) Seven mountains, Huntingdon and Union
counties ; 7 cross sections by d'Invilliers. (2) Perry
Co. synclinals ; four illustrations. (3) Map of the
same two grand synclinals.
LIST OF ILLUSTRATIONS. xix
Page.
660 (XCI). Perry county faults and folds ; 2 cross sections
nnd a map of Centre township.
662 (XCII). Perry Co. fault, four illustrations. (2) Little
Germany fault map. (3) Spring * township zigzag
belts.
664 (XCIII). Blue mountain map, by G. Lehman.
666 (XCIV). The same continued east to include Port Clin-
ton and the Little Schuylkill river.
668 (XCV). Seven Mountain sections, Nos. 8 and 9.
670 (XCVI). Seven mountain sections, Nos. 10 and 11.
672 (XCVII). Seven Mountain sections, Nos. 12 and 13.
680 (LIII). The Arch Spring in Sinking Valley, Blair Co.,
picture by Lehmann, from Geol. Pa. 1858. (2)
Catioe mountain terrace (Oneida, IVa.), as seen from
head of Sinking Valley.
700 (LVII). Model of the surface of the Medina No. IV in
middle, northern and northeastern Pennsylvania, as it
existed after elevation and plication, and before ero-
sion ; constructed by J. P. Lesley. Photograph in
slant light from the S. E.
702 (LVIII). The same photographed in light from N. W.
714 (CXI). Fossils of IV, Oneida and Medina.
INTRODUCTORY CHAPTERS.
CHAPTER I.
Our Geological Knowledge.
A summary description of the geology of Pennsylvania
implies a condensed account of all the work done by the ge-
ologists of the state survey for fifty years, together with the
knowledge produced by some thousands of private explora-
tions. It is a task made difficult, not so much by the ex-
tent and diversity of the territory to be described, as by
reason of the great number of rock formations which ap-
pear at the surface, and the erratic courses which their out-
crops pursue ; by the local variations of character exhibited
by them ; by the complicated structure of the underground ;
by the multitude of mineral beds having an economical
value ; by the eruptions of volcanic rocks in different places,
and the extensive rnetamorphism of the older formations in
the southeastern counties; and by the concealment of a con-
siderable portion of the rock surface of the northern and
western counties beneath a covering of glacial drift.
So great is the variety of objects of geological interest
which present themselves to the eye of a skilled observer at
every point, that we may justly consider the number infi-
nite which offer themselves for investigation in an area of
50,000 square miles ; that is, within the limits of our state.
A small spot upon the surface of the whole globe Pennsyl-
vania is nevertheless a world in itself, to the just contem-
plation of which the liveliest imagination can rise only by
a great effort ; one of those objects of contemplation pre-
sented to the mind of man before which it bows with all
its faculties of logic and rhetoric in reverence, imperfectly
comprehending what it sees, and hopeless of framing an
adequate salutation to it. For, the longest and most in-
timate conference with these phenomena of Divine operation
2 GEOLOGICAL SUKVEY OF PENNSYLVANIA.
will not enable the greatest genius to do justice to their
description.
The geology of such a territory is a history of the works
of nature through a lapse of time, which, if compared to the
life of a man, or even to the existence of the human race, is
little less than an eternity. Events of the greatest magni-
tude and complexity have followed each other in uninter-
rupted sequence, without known beginning, and without
yet reaching an end. Geologists spend their lives in de-
ciphering the hieroglyphic records of this history, only a
part of which are legible, and the largest part is concealed
entirely from view. One fact at a time may easily be noted ;
a group of facts may be compared and discussed with
pleasure and safety ; but the geological drama has been
played out upon an imperial stage, by combined and con-
flicting natural forces in company, according to a plot not
yet revealed, beginning in ages previous to the creation of
any living being. The drama was played without an audi
ence. Therefore, the geologist who makes himself its re-
porter is soon lost in amazed bewilderment ; and when he
takes his pen in hand will pray for the pardon of innumer-
able mistakes before he yields to the necessity of commit-
ting them.
The great English historian of the last century, Gibbon,
'has left for our instruction a luminous description of the
difficulties to be overcome and of the successes to be
achieved by a narrator of human events when twenty years
of zealous preparation is followed by twenty years of patient
execution. He tells how many languages had to be ac-
quired, how many previous works of genius mastered, how
many original documents deciphered, what toil, what
doubts, what discouragements had to be endured. He
paints a touching picture of the mingled pain and pleasure
with which he ended his task, and closing his book bade a
lingering adieu to the occupation of his life.
The geologist is a historian in every sense of the word ;
subject to the same disabilities and exposed to the same de-
ceptions ; handling a mass of fragmentary records ; cross-
examining unintelligent and unsympathetic witnesses ;
OUR GEOLOGICAL KNOWLEDGE. 3
judging conflicting testimonies ; following trains of events
which pursue parallel lines separated along shifting boun-
daries but mutually affecting each other's characters.
But while the historian of human affairs writes under the
safe guidance of well-known and well-understood prin-
ciples of human nature, the motives of which he has him-
self experienced, and by which he may interpret with a near
approach to truth the actions of his historical characters, so
as to rill out the rude and slender sketches of tradition, or
detect and amend the mistakes of ancient documents, it is
the ill fortune of the geologist to be compelled to write the
physical history of the globe, or a part of it, in almost com-
plete ignorance of those fundamental principles of his
science on which he should rely for all his explanations. It
is true that the collection of geological facts has become in-
credibly great, but it is also true that from this very wealth
of facts springs the impossibility of any description of them
which shall satisfy the common mind, while the geologist
himself, if not completely lost in the wilderness of details,
either becomes a slave to his own favorite theories, or stands
uncertain between the views of jarring schools.
None of the greater questions in geology have yet been
answered. We know nothing of the interior of the earth
beyond a depth of about five miles and that only at a few
points. We are ignorant as yet of the exact cause of
earthquakes, and of the origin of volcanoes. The history
of the crystalline formations remains mysterious. We
cannot yet explain the elevation of a continent, with its
systems of faults and folds; nor the submersion of the-
ocean bed. The relative distribution of land and water has.
been changed in every age, but how, how much, or why r
we do not know. Consequently no geologist has succeeded
yet in even plausibly mapping the surface of the earth 'as
it was at any past time, with river drainage on land, and
its deposits in the sea. The courses of those ancient ocean
currents are unproved which distributed the river sedi-
ments. Ancient lakes, with or without outlets, are known
to have existed, but their limits have been destroyed and
their extent is a matter of guess work. The connection of
4 GEOLOGICAL SURVEY OF PENNSYLVANIA.
even great formations in distant countries has been broken
and cannot be' restored. The migration of living creatures
from one region of the globe to another, under the stress of
a change of temperature, or the prevalence of enemies,
introduces an element of deception into the arrangement
of any lime-table for the globe, or even for a subordinate
division of one continent. We know not if the sun has
always shone upon the earth with the same energy of light
and heat. We know not if the tides in past ages have or
have not been more efficient at their work. The composi-
tion of the atmosphere may have greatly changed, nor have
we any means for settling that question.
The geologist then must examine and describe his special
region in a deceptive twilight of science. Detailed reports
of business properties are not affected by such fundamental
difficulties, but a description of a region like Pennsylva-
nia pretending to display a summary of our knowledge of
it, must cautiously handle all the generalities and be con-
tent to leave great questions unanswered and a thousand
facts unexplained.
CHAPTER II.
(Geological Time.
Time and space are the two eyes with which man looks
upon the world, the two lenses which he uses for examin-
ing-, defining and measuring whatever has attracted his
attention or excited his thirst for knowledge. In every
branch of science, in every business, in every handicraft,
in the tine arts, well-defined and common standard measures
of time and space have been invented, and in the present
century refined to the utmost precision by delicate instru-
ments.
The science of geology has its own apparatus, and no
description of the geology of a place or of a region can be
either written or comprehended unless both the writer and
the reader are inspired by the sincerest respect for an
accurate application of the standards of time and space to
all and each of the whole series of observed facts.
The idea of time is the most fundamental of all geolog-
ical ideas, and at the same time is to most minds the
vaguest. To count the minutes in an hour, the years in a
century, or the centuries in the Christian era has become
a familiar and easy mental operation for all educated per-
sons, and the few] who have pursued historical studies
possess clear notions of dynasties for two or three thousand
years before the time of Christ. But to the majority of
mankind any statement respecting previous ages in the geo-
logical history of our planet is unreadable because written
in a time-language which they cannot appreciate. The
great operations of nature have been so exceedingly slow
and have been carried on through so many ages, each of
vast duration, that untrained minds become confused and
weary with them.
Nevertheless the geologist is compelled to describe rock
formations in an order of their successive deposits; and he
can make their nature clear in no other way than
6 GEOLOGICAL SURVEY OF PENNSYLVANIA.
explaining the comparative quietness, or the comparative
commotion of the age of each. Going backward in time
and downward through the rocks, he is compelled to give
time-names as well as mineral-names to the formations or
groups of beds which he describes. Bat his time-names
can only be comparative, such as new and old, newer and
older, recent, ancient and archaic. And his mineral-names
also can only be comparative : upper, middle and lower.
These terms, however, can present no well-defined idea to
any mind but that of a geologist, for they are the terms in
daily use among men for events which run their course in
a few days, or years, or centuries of human time, or for
things which are measurable by inches, yards or miles in the
country where those who use them live. A single one of
the principal rock formations of Pennsylvania required
more time for its deposit than the duration of the human
race from its first appearance on the planet until now. The
age of our primeval forest can hardly compare with the age
which one large coal bed reached before its life was destroy-
ed by the invasion of the overlying sands. If the limestone
deposits of the Cumberland valley could be measured not
by feet and yards but by years and centuries, and com-
pared with events of human history, we should merely get
a vague notion of enormous time, expressed by the old
phrase "a thousand years is as a single day."
Nevertheless, however ineffectual will prove the effort to
frame a clear idea of the whole course of geological time, or
even to define with any distinctness its major sub-divisions,
it is absolutely indispensable for the understanding of the
geology of any region to suspend our habitual estimates of
human events, and substitute for them the largest possible
conceptions of geological time, upon the grandest scale
which we are capable of imagining.
To the human individual who seldom lives beyond three-
score years and ten, and whose short life is crowded with
business affairs, time is considered a precious commodity to
be spent with economy, its loss and its waste lamented, and
its use converted into a religious duty.
But these ideas are products of the latest age of human
GEOLOGICAL TIME. 7
history, and are essentially ideas of the modern factory and
counting-room. Disembodied immortal spirits would value
time by a different standard. Science, especially the science
of geology, 'dispenses time as the commonest drug in the
market of the universe.
The idea of precise time is the product of the routine of
civilized human existence. It is unknown in the vegetable
and animal worlds ; it is disregarded by nomadic races.
The idea took root when the home was organized by woman,
and meals were cooked at fixed hours of the day. It be-
came" "confirmed when superstition organized priestcraft,
and religious ceremonies demanded a calendar. The moon
was the first clock. The invention of the water-clock by the
ancients was made for the benefit of the wealthy and cere-
monious. The first mechanical clock in Europe was one
sent as a royal present by the Caliph Haroun-Al-Rashid of
Bagdad to Charlemagne. Even now, with all the chro-
nometers of Christendom, it is still a fact that nineteen-
twentieths of the human race have never seen a clock, and
have no.practical need of one.
The idea of absolutely precise time came with the inven-
tion of the steam engine, the locomotive, and the telegraph,
and with the erection of modern observatories. It bears the
same relation to the crude instinct of time in the mental
constitution of the race that the few and costly ingots of
aluminium bear to the sum total of common clay with
which the world is full. But, with the spread of civiliza-
tion, and the multiplication of machinery, popular educa-
tion will in the end fix it in the minds of all.
Whatever moves with regularity, continuously, by steps
or stages equal to each other, and therefore countable with-
out being accountable, or disturbed by perturbations, is a
clock is a measurer of time a scale by which the rate of
the course of events can be recorded. A locomotive, a
power loom, a printing press, any engine adjusted by a gov-
ernor to invariable motion, a sewing machine driven by a
well-directed foot, is a clock. All reciprocal motion, all
rotary motion can be set to keep time. The melting snow
water dropping from a roof will furnish a geologist with a
8 GEOLOGICAL SURVEY OF PENNSYLVANIA.
measure for calculating the annual rate of growth of stalag-
mites in a limestone cave.
The essential nature of a clock is its regularity ; and that
depends on the energy which moves it ; while the rate of
its own particular motion depends on its construction, a
short pendulum ticking seconds, a long pendulum ticking
minutes.
But while the geological world is full of natural time-
markers, they are of every variety of construction, and
therefore furnish no common standard of time. The geol-
ogist who seeks to investigate the age of the globe stands
like a purchaser in a clock-makers shop, surrounded by a
thousand time-keepers all ticking at once but not together,
independent of and indifferent to each other's rate of going,
and waiting for their turn to be adjusted to a common rate ;
the little ones, like children out of school, rollicking in an
ecstasy of quarter seconds ; larger ones soberly stating
their movement in seconds ; here and there a great pendu-
lum disdaining to record its relations to universal time
oftener than once a minute.
In the world of physical science entomologists, concho-
logists, ornithologists apply to use only the little patent
levers and repeaters ; while the mineralogists, the geologists
the astronomers, in their several calculations work only
with cathedral clocks. But in all branches of physical
science without exception the differentiation of time is
accomplished naturally and is illustrated scientifically by
natural phenomena in one way or in another, on a smaller
or on a grander scale, and at rates so immensely different
that, while whole series of thousands of one kind complete
their cycles of existence within the lifetime of a man,
others require a thousand centuries to substantiate one
item ; and this is what happens in geology.
Now, for such phenomena geology has as yet failed to
find any precise measuring time-machine, any clock, and
must still content itself with rudely divided scales of rela-
tive proportion without knowing the actual sizes of their
aliquot parts. But geologists, being now emancipated
from the superstitious belief that God created the world in
GEOLOGICAL TIME. 9
six days, or in six ages, are free to gaze back along an
interminable vista of events, having modern human history
with its accurate chronology of days and years in the fore-
ground, through the middle distance of classical and monu-
mental history measured by [olympiads, centuries and
dynasties, into a background of pre-historic and glacial times
unchecked by any measurable records ; beyond which is
dimly seen an infinite extent of geological times, ages and
formations, vanishing in the extreme distance toward some
absolutely unimaginable beginning.
In contemplating this grand picture from day to day, as
the geologist is obliged to do, two sentiments take posses-
sion of him : an admiration for the variety and multi-
plicity of the things which have happened ; and a profound
conviction of the slowness of time, the infinite patience
with which the world has been made. And these senti-
ments are the product of observation ; are neither a fancy
nor a faith.
It is evident to observation that the clock of nature has
ticked regularly; that the same physical forces have oper-
ated through all time in the same way as they are seen
operating at the present moment; that in every age rivers
have been delivering leisurely their burdens to the sea in
obedience to the varying rainfall of the seasons; that the
forests have spread and disappeared again, successively
occupying for centuries the soil; that living creatures of a
million kinds have made their appearance on the planet
in an orderly series, the rule of which we do not understand,
but the order of which is plainly although not completely
revealed by fossil remains imbedded in the rocks. For it
is impossible for any sane man to doubt that the rate of
life with which we are familiar now was in every geolog-
ical age the rate at which animated creatures were gener-
erated, grew, propagated their kind and perished. No
reason can be given for supposing that the cockroach
whose form is imprinted on a shalyroof of a coal-bed lived
either a shorter or longer life than the cockroach of the
modern dwelling ; or that the Eurypterids in the Darlington
shales of Beaver county had a different life experience
10 GEOLOGICAL SURVEY OF PENNSYLVANIA.
from that of any modern lobster on the New England
coast. The great pachyderms whose skeletons have been
transferred from the clays of the Rocky Mountains to the
museums of New Haven, Philadelphia and Washington,
by Leidy, Cope and Marsh, no doubt lived each one as
long a life as a modern elephant, rhinoceras, tapir, horse
or elk. The ancient coral reefs of which the limestone beds
behind the Blue Mountain at Stroudsburg, Danville,
Lewistown, Tyrone City and other places in middle Penn-
sylvania, must have grown as slowly as grow now the Mad-
repore reefs off the Florida coast.
But beyond this general conviction that the ordinary
events of nature in the mineral, vegetable and animal
worlds have been pursuing the even tenor of their way
through all geological ages, we cannot go. We cannot
divide geological time into centuries, much less into years;
but we can and must apply the conviction thus obtained
that geological events have slowly come about to explain
how they came about and in what order they occurred.
When this fundamental idea of immense stretch and suc-
cession in geological time has become familiar to the public
mind the greatest difficulty will have been removed from
the path of the geologist in his efforts to describe the'
geology of any district or region like Pennsylvania ; and
only for this reason is it insisted upon here. To make it
still more plain the following illustrations of its truth
will be adduced and specimens will be given of the calcula-
tions of geological time attempted by recent writers.
The annual growth of trees, interrupted by the winter, is
marked by their rings of bark, so that the age of a tree can
be discovered by the number of these rings. In like man-
ner the deposits of a river are more abundant and of a
coarser quality after long-continued rains ; so that a section
of a sand bank or mud flat at the mouth of a river should
mark the course of time by thin layers of fine clay and
coarser sand alternately. This fact has been taken ad-
vantage of by those who have investigated the history of
Egypt. The regular inundation of the Nile, commencing at
midsummer and lasting a hundred days, covers the valley
GEOLOGICAL TIME. 11
and the delta with a sheet of fertile mud. The turbid waters
then fall, the land emerges, the winter passes. In March
the hot dry khamzin blows, and clouds of sand sweep
across the surface, depositing a layer of yellow desert dust
upon the previous layer of Nile mud. This takes place
year by year with the regularity of clock-work. Shafts
have been sunk through these alternate layers to the floor
on which some monument of antiquity was erected four
thousand years ago, and the counting of the alternate
layers has verified its recorded date. In some of these shafts
sunk to a greater depth fragments of human pottery have
been discovered, and by the number of layers of mud and
sand it has appeared that human beings pursued their
handicraft at least fifteen thousand years ago. It is evident
that, were a proper site on the shore of the Mediterranean
between Rosetta and Damietta selected by the Egyptian
government, 'and a shaft sunk deep enough to reach the
original bed on which the delta of the Nile began to be de~
posited, it would be possible, either by counting the alter-
nate layers of sand and mud, or by simply estimating their
average number in each foot or yard of the descent, to cal-
culate with considerable accuracy the geological time at
which the drainage of old ^Ethiopia adopted the present
valley of the Nile for its most convenient route to the sea.
The Nile indeed in this respect stands alone among all
the rivers of the world ; the only river which receives no
side streams for fifteen hundred miles of its course, re-
sembling thus the unbranched date palms which spread
their annual plumes at the top along its bank ; the only
river which deposits all its burden during half a year, and
waits to give the atmosphere an equal chance for depositing
its special burden of a different kind. But all the rivers of
the world have seasons of copious outflow and increased
deposit ; therefore all the river sediments of the world are
composed of alternate layers of coarse and fine material ;
and as we go back in geological time, making sections of
older and older river sediments, more and more packed and
consolidated, hardened, dried and converted into shale and
sandstone rocks, the geologist observes in all of them this
12 GEOLOC4ICAL SURVEY OF PENNSYLVANIA.
fundamental character of alternation ; the incontestable
proof of their origin as river sediments ; affording an irre-
sistible conviction that they grew, layer upon layer, annu-
ally, through ages of immense duration rudely measurable
by their several thicknesses.
The same lesson is taught in other ways ; as, for example,
by the annual layers of autumn leaves which have been
blown upon the surface and sunk to the bottom of still
water ponds and little lakes in the forests, with the eggs of
insects attached to them, and the wings or bodies of dead
insects imbedded with them. A deposit of this kind i-n
Switzerland is described by Heer as thirty feet thick, and
shows thousands of such alternate layers of black vegetable
matter and fine white clay, each no thicker than a sheet of
paper, marking the quiet alternation of annual seasons for
many thousand years.
The influence of wet and dry seasons in tropical countries
marks the annual stalactite growth in limestone caves. For
in the rainy season an abundance of water falling on the
surface finds its way to the roof of the cave charged with
carbonate of lime, and the dropping in the cave goes on
with great rapidity. But in the following dry season the
growth of the stalactite stops, just as the life of a tree sleeps
during the winter; and thus the stalactite has its annual
rings of growth like a tree, from which its age can be esti-
mated. The stalagmite floor of such a cave consists of suc-
cessive sheets ; and in the case of one Brazilian cavern, thirty
thousand of these annual sheets have been counted.
There is a little brook in Switzerland called the Tiniere,
which has its springs in the mountains of Berne, and de-
scends through a narrow ravine which it has cut for itself
down to the bank of the Lake of Geneva near Vevey. Fed
by rains, cloud- fogs and melting snows it wears away the
rocks through which it passes and spreads sheet after sheet
of sand and clay over a little fan-shaped mound which it
has accumulated at its mouth. A railroad has been cut
through this mound, showing its dome-shaped structure,
and the slow and gradual way in which it has been made.
In the sides of the railroad-cut three long black streaks are
GEOLOGICAL TIME. 13
visible one above the other. They make three long arched
lines. They consist of vegetable matter mixed with frag-
ments of charcoal, pottery, and the implements of man.
They represent three times at which some tribe of Swiss
aborigines selected the mound as habitable ground, resid-
ing upon it awhile until destroyed or driven away by some
unusual violence of the little river descending from the
mountains, or by some pestilence or invasion of hostile foes.
Although the three arched streaks are separated from one
another by only a few feet, the intervals must needs represent
great lengths of time ; for, the three settlements were made
by different races ; for, in the lowest arch no tools were
found except stone axes, and chisels, and needles of bone.
In the middle streak were found beside these instruments
made of brass ; and in the Upper streak, manufactured tools
of iron were discovered. Therefore centuries probably
elapsed, the mound always growing higher and higher very
slowly, new tribes coming into the region with advancing
civilization seeking places to live on. As no alternate layers
in the mineral constitution of the mound could be made use
of for calculating this rate of growth, the Swiss geologists
resorted to another method, which is one of universal ap-
plication in the geology of sedimentary rocks of the globe.
They measured the amount of water annually flowing down
the Tiniere ; they measured the quantity of solid matter
held in suspension by the little river at various seasons of
the year. From these two data they calculated the thick-
ness of stuff spread over the whole extent of the mound in
a single year, taking this thickness as a unit of measure-
ment for the depth of the lowest streak beneath the present
surface of the mound. It resulted from the calculation,
that the people who left their stone axes in the lowest
streak lived about seven thousand years ago; and the ap-
proximate accuracy of the calculation was confirmed by a
similar process of thought applied to the case of human
habitations buried in a little delta at the mouth of one of
the rivers of the Jura, by the gradual enlargement of which
the lakes of Neufchatel and Bienne, originally one lake,
has been separated into two. In this case also the age of
14 GEOLOGICAL SURVEY OF PENNSYLVANIA.
the human remains was found to be about seven thousand
years. But in both these cases, which are exceptionally
favorable for estimating the time of the occupation of the
mounds by man, no knowledge is obtained respecting the
far greater lapse of time previous to their first occupation
during which the two rivers mentioned had been doing the
same work in the same way, work the beginning of which
goes back into the last geological age.
A bridge was built by the Romans from one vertical wall
to the other of a deep and narrow ravine in the center of
France. For unknown ages a river of Auvergne had been
working its channel down through a lava bed, undermining
and throwing down one after another of its basaltic
columns, grinding them up into black mud and delivering
the- mud to the Loire to be deposited in the Bay of Biscay.
The Roman bridge is broken, but its arches still cling to
the walls of the chasm, showing that this has not been sen-
sibly widened in two thousand years. A flagrant proof of
the extreme slowness with which the erosion of the surface
of the earth has ever been going on ; and we may turn from
the basaltic columns in Auvergne to the great canon of
Colorado or any of the gaps in the mountains of middle
Pennsylvania with a sentiment of profoundest conviction
for their vast antiquity. The process of destruction is
evident ; it goes on before our eyes daily and annually; "but
unless we have a sound conviction of its infinite slow-
ness we shall fall into the popular superstition which prat ties
about convulsions of nature which never occurred, and fails
to realize the true character of the events which the geolog-
ist has to describe.
The lesson of geological antiquity is taught with equal
clearness by the series of volcanic eruptions which mark
the whole history of the earth from the beginning to the
present day; and although evidence of the exercises of the
eruptive forces on an exceptionally grand scale at certain
times is not to be mistaken, corresponding to the greater
and the more widespread earthquakes which have some-
times varied the importance of calamities in human history,
they cannot be considered in any other light than as excep-
GEOLOGICAL TIME. 15
tions to the regularity of the whole series of volcanic phen-
omena, which in the gross has undoubtedly been as regu-
lar, and has proceeded as leisurely as -any other function of
nature. Vesuvius at the Christian era had been asleep from
beyond the earliest traditions of the inhabitants of Italy;
its old crater was a cattle ground of Umbrian cow-herds,
and accounted so safe from all commotion that Spartacus
encamped his army in it as an impregnable fortress. When
the rirst eruption awoke the mountain to renewed activity,
pouring a sheet of lava over Herculaneu m and covering Pom -
peii and the surrounding country with ashes, men were as
much astonished as we should be were the old vents in York
and Adams county to be again re-opened and fresh streams
of lava pour from them over our cultivated fields. Since
Pliny's day the activity of Vesuvius has been continuous,
its eruptions recurring every few years, yet without sensi-
bly increasing the size of the cone. Therefore, the con-
struction of the cone must date back in ages previous to the
appearance of man. Every volcanic mountain in the world
has grown like a vegetable bulb, skin over skin, through
wastes and wildernesses of time of whfch the human imag-
ination can form but a vague idea, and which the science of
geology can only indicate by reference to the geological age
of that particular formation in which the lirst appearance of
such cones can be recognized. Every geological age had its
own volcanoes, its own outflows of lava and its own tufa
beds. The backward vista is interminable ; the cause is
unknown ; their phenomena have pervaded the ages from
the beginning.
It is a seductive temptation to the speculative geologist
to translate the vague ideas of geological time into figures.
But whether the results of any calculation thus mathe-
matically stated increases our knowledge or clarifies our
ideas may well be doubted ; for after all, when the product
of multiplying large numbers reaches into the millions it
merely generates the idea of vastness. To write the sum of
a hundred million years helps us. no better than to write
the words infinity or eternity. Yet the effort at such a cal-
culation is a useful exercise of the mind and furnishes an
16 GEOLOGICAL SURVEY OF PENNSYLVANIA.
opportunity for examining the facts which must be used
in making the calculation. With this end in view one or
two such calculations will now be given.
The western coast of South America has been lifted from
the ocean to a great height in the air by successive earth-
quakes, one of which suddenly lifted it three feet since the
settlement of Chili by the whites. Marine shells can be
broken out of the rocks at a height of 16,000 feet above the
sea. The average rate of this upheaval is of course
unknown; but should we base a calculation upon the
observed rise of the land of northern Scandinavia, namely,
live feet in a century, the rocks containing these fossil
shells would be 320,000 years old. From the character of
the shells we k-now that the rocks which hold them were
deposited in what is called the Jurassic age. But if all
known geological time were represented by the twelve hour
divisions on the dial of a clock, the Jurassic age would be
at about nine or ten o'clock, and therefore the highest
antiquity we could give to the mountains of South America
would represent but a portion of geological time.
While parts of the crust of the earth are slowly elevated
other regions are slowly sinking into the sea. In middle
Pennsylvania we have a series of great formations lying one
upon another, all of them originally deposited in succession
in a great water basin which in early times occupied the
area of the United States. Some of these formations were
spread upon the bottom in deep water; some of them in
water so shallow that they exhibit mud cracks, ripple
marks and foot-prints such as travelers notice everywhere
on sea beaches. They hold both shore-living shells and coral
reefs. These facts compel us to believe that the bottom of
the Pennsylvanian sea kept on sinking through all the ages
during which these deposits of limestone, sand and clay
were made in it ; and probably at a rate proportionate to the
inflow of the solid materials from the rivers around it. The
rate of sinking is of course unknown, but must have been
as slow as the wearing away of the surrounding lands.
The total thickness of these deposits, measured from the top
of the coal measures down to the bottom of the great lime-
GEOLOGICAL TIME. 17
stone of the Nittany valley at Birmingham in Blair county,
is not less than 40,000 feet. If the geologist prefers to take
the Scandinavian rate of elevation as a measure for his cal-
culation, five feet in a century, he gets 800,000 years. This
result is indeed a most uncertain approximation to the
truth, and is of no scientific value whatever, but it will serve
admirably well to impress upon the mind the reality of the
vast antiquity of that part of the surface of the globe which
we are competent to examine. Considering the fineness of
nineteen- twentieths, say ninety-nine-hundredths of the 13
formations which appear at the surface in middle Pennsyl-
vania, the'rate of their deposit must have been lower than five
feet in a century, and consequently the length of time
required much greater than the result of the calculation.
The tidal layers of red mud in which were found at Potts-
ville by Dr. Lee and Professor Rogers the "foot-prints of
shore-feeding animals, measure 2,000 feet in thickness.
The fine dark mud and sand formation through which the belt
of roofing slate in Lehigh and Northampton counties runs
is at least 6, 000 feet thick. The Carboniferous formation at
the top of the series, with its slow-growing coal-beds, and its
slowly deposited limestone, fireclay and shale beds is 3,000
feet thick. Taking these three formations together, apart
from the other ten, we have 12,000 feet of sediments which
might have had a rate of deposit no greater than a few feet
in a century, requiring a million years.
In another part of this book will be described the folding
of the Paleozoic formations of middle Pennsylvania, with
basins five miles deep, and arches five miles high; Al-
pine ranges which once traversed our State ; now reduced by
the frosts and waters of ages to within a thousand or two
thousand feet of the level of the sea. A whole world of
rock has been dislodged, ground up and carried by the
Juniata, the Susquehanna, the Schuylkill and the Delaware
into the Atlantic. All southern New Jersey, Delaware,
Maryland and the general Tide Plain of the southern states
have been constructed by the rivers which have been
engaged since the age of the coal measures in eroding the
great rock folds of the Appalachian belt. Can we find in
2
18 GEOLOGICAL SURVEY OF PENNSYLVANIA .
I
what goes on before our eyes to-day a measure for this
erosion. Certainly not one of any accuracy. Yet one is at
hand which will give some good idea of it.
The Juniata river is said to pass at Millerstown in Perry
county about 24, 000, 000 cubic feet of water per hour ; hold-
ing enough sediment in suspension to represent in the course
of a year about 1,000,000 cubic yards of the rock waste
which its innumberable branches are robbing from the
mountains. Considering the whole water basin of the upper
Juniata, the erosion going on must lower its general surface
about one foot in 1,500 years. The original surface of the
region was on an average say 9,000 feet above the present
surface of the country. This gives us 13,560,000 years as
the length of time during which the Juniata has been carry-
ing the rock waste of its own special upper country into the
sea; and all the other rivers of the Atlantic coast have been
doing the same work at the same rate during the same
length of time. No wonder we have the great lowlands of
the Atlantic coast, now cultivated by man ; and the vast
sloping sea-bottom which has its continuation under water
from the line of coast far out to the submerged precipice
which the soundings of the Coast Survey have shown to
be the border of the gulf stream.
The work done by the Mississippi river has been ascer-
tained with considerable accuracy by the United States
Army Survey under Humphreys and Abbott. At its
present rate of work (which alone can be studied) it removes
from the face of the immense region between the Allegheny
and Rocky mountains one foot of surface depth in 6,000
years. It is impossible to state the original height of the
general surface of the Mississippi water-basin in the coal
era when the great river began its operations. From some
districts like middle Kentucky and Ohio it has removed all
the formations from the top of the coal measures nearly to
the bottom of the series, a thickness of say 10,000 feet.
In other parts, as at Pittsburgh, the erosion amounts to only
2,000 feet. If an average of only a thousand feet be as-
sumed the age of the Mississippi would be 6,000,000 years.
The science of geology in its present stage is like a river
GEOLOGICAL TIME. 19
bearing variable 'quantities of solid matter which can be
seen and felt, and quantities of invisible chemical solutions.
It consists of an abundance of indisputable facts, mixed
with innumerable fugitive suggestions, hypotheses and"
theories, changeable in their nature and subject to present
and future criticism. The accumulation of facts which re-
main the permanent body of the science increases continu-
ally and at an accelerated rate from year to year. The
study of one mineral bed after another and one geological
locality after another is gradually procuring a sound and
useful knowledge of the structure and mineral wealth of
regions. Thus the beneficial work of good geologists is in
favor of the business community, which troubles itself little
about questions of cause and effect, and is well content with
definite statements of quality and quantity, seeking only to
learn where the useful can be found and how it can be
cheaply got. Yet the discussion which forever goes on in
the geological profession respecting the origin and age of
minerals appeals strongly to the intelligent curiosity of ed-
ucated men of all classes, and, in so far as they can be
understood by laymen, make an important part of the gen-
eral education of the community.
The race of man differs from the races of animals in pos-
sessing not only a more powerful reason, but the faculty of
imagination, by which man sees the invisible, and can ap-
preciate the past. In science the business of the imagina-
tion under the guidance of mathematics is as important as
the business of the judgment under the guidance of the
senses. Without imagination men would be like savage
tribes before the horse was tamed. The prosaic mind goes
afoot and travels in a narrow circle around its dwelling
place, knowing so little of the world beyond that it cannot
comprehend its own vicinity. The geologist finds such
minds everywhere. They are incapable of seeing what he
sees both in the distance and in the depth, because the im-
agination which they possess has not been cultivated like
his own. He rides his imagination like a winged horse in
all directions, far and near, collecting knowledge from every
quarter. In telling his science he speaks from horseback to
20 GEOLOGICAL SURVEY OF PENNSYLVANIA.
men on foot. His steed may be better or worse. He has
his own adventures with it. It sometimes stumbles, some-
times he is thrown, and sometimes he is run away with.
When the imagination is of the finest quality it must be
ridden with a curbed bit and a strong rein. The tendency
to exaggeration in geology is especially great. It gathers
force and velocity by indulgence, like a rock descending a
mountain slope. So, exaggeration in the estimate of geo-
logical time has been carried by the vivid imagination of
some geologists to a wholly unreasonable excess, yet always
under the form of mathematical calculation, dealing with
absolute facts which the most sober reasoner cannot deny,
and which are the products of the most careful observation
and the most skilful investigation by geographers and
chemists. A single illustration of such exaggeration will
suffice.
An English geologist of eminence has recently discussed
with great ability the quantity of soluble and insoluble sub-
stance carried into the sea by rivers. Combining Herschel's
estimate of 2,494,500,000,000,000,000 of tons of water in the
world ocean, with Frankland's analysis of 100,000 tons of
sea water holding 1,017 tons of the sulphates of lime and
magnesia, and 49 tons of the carbonates of lime and mag-
nesia, he gets 1,222,000,000,000,000 of tons of carbonate of
lime and magnesia in the world ocean, a quantity sufficient
to cover 50,000,000 square miles of land with a layer 13 feet
deep, and 25,000,000,000,000,000 of tons of sulphate of lime
and magnesia, a quantity sufficient to cover the same num-
ber of square miles with an additional layer 265 feet thick.
He estimates that the rivers of the world remove annually,
on an average, from each square mile of continental surface
100 tons of rock matter ; and that the proportionate amount
of its various substances would be as follows : Of car-
bonate of lime, 50 tons ; sulphate of lime, 20 tons ; silica,
7 tons ; carbonate of magnesia, 4 tons ; sulphate of mag-
nesia, 4 tons ; per-oxide of iron, 1 ton ; chloride of sodium,
8 tons ; and 'alkaline carbonates and sulphates, 6 tons.
Taking first the carbonates of lime and magnesia, re-
moved from the land surface and deposited in the sea at the
GEOLOGICAL TIME. 21
rate of 54 tons per square mile per year, it must have re-
quired 480,000 years to charge the ocean water with the
amount of these salts which Frankland says it holds.
Taking next the sulphates of lime and magnesia he gets
25,000,000 years.
Treating the chlorides in the same way he gets 200,000,000
years.
Estimating the amount of mechanical sediments or solid
matter carried by a river to the sea at six times greater than
the chemical solution, that is, 40,800,000,000 tons per
annum ; and considering the total surface of the globe
197,000,000 square miles (one cubic mile weighing 10,903,-
552,000 tons) he concludes that it would require for cover-
ing the whole globe with a rock formation of every kind
one mile thick, 52,647,052 years ; and, therefore, if the
geologists estimate all known formations taken together as
measuring 10 miles in depth, we must suppose that the first
rocks were deposited 526,000,000 years ago.
All that can be said respecting any such calculation is
that it has no scientific value whatever, although based upon
acknowledged facts ; but, as has been already said, it will
help to make far lower estimates of the age of the world in-
telligible and credible.
22 GEOLOGICAL SURVEY OE PENNSYLVANIA.
CHAPTER III.
Geological Dimension.
The second fundamental element of geological thought is
the idea of space in its three dimensions of length, breadth
and thickness. Any transcendentally imagined fourth
dimension must appear to be absurd. Astronomy deals
with unimaginable and infinite distances, as its sister
science, geology, deals with unimaginable if not infinite
operations of time. In both cases the common mind is
subject to a thousand deceptions. Who can believe that
the moon when it rides in a clear night through the atmos-
phere to all appearance no higher than balloons could
mount or an eagle soar, is in reality 240,000 miles distant
from the spectator, sixty times the radius of our globe. And
yet this distance is the smallest of the heavenly spaces.
The sun's mean distance from us is 92,000,000 of miles;
while the light of the nearest fixed star traveling at the
rate of 200,000 miles a minute does not reach us until after
a journey of eight days. Such ideas would seem to be useless
to the practical geologist. But no truth is useless; all
knowledge is practical either in its direct application to
facts or in its education of the finer qualities of the mind.
No man can rightly understand the descent of a coal bed or
ore vein from the surface into the depths of the underground
unless his imagination is disciplined to estimate properly
the dimensions of space, and by habituating himself to the
measurement of distances of all grades, long and short, he
acquires the power of calculating those lengths and breadths
and depths which are within the scope of mining opera-
tions.
To the practical astronomer our globe seems as small to
the surrounding solar system as a grain of sand compared
with the mass of a mountain. To the practical geologist
GEOLOGICAL DIMENSION. 23
who compares the whole globe with the spot on its surface
which he is studying for practical purposes, it seems infi-
nitely great. It is hard to conceive the depth at which the
center of the earth lies beneath our feet; it equals the dis-
tance from San Francisco to Newfoundland or from Phila-
delphia to Berlin.. Only those who travel extensively can
estimate the size of the continents and oceans of the world;
those who circumnavigate the globe; he who travels round
it in 80 days. Were a continuous first-class railway laid
like a hoop of iron on a great circle, an express train
running at a schedule rate of 40 miles an hour would
require 24 days to come around to its starting point.
Of this great globe nothing is known by the geologist
except its thinnest skin. The deepest boring has pene-
trated it only to the depth of little more than one mile. If
all known sedimentary and crystalline formations at their
greatest thickness were added together, the sum total
would not amount to 20 miles. These 20 miles in depth of
rock carry us back through all the known ages of geolog-
ical time. The rest of the globe, unknowable and unimag-
inable, must represent an infinite lapse of previous time.
In describing an area of the earth' s surface like the State of
Pennsylvania, the first thing to be done is to get a right idea
of its actual size, not so much in relation to the whole surface
of the earth as in relation to the whole area of the North
American continent, over which its rock formations spread
and in which they may be studied far beyond the limits of the
state. Pennsylvania is about 300 miles long and 150 miles
wide, a mere spot on the surface of the globe. Its geological
formations extend into surrounding states with areas as large
or larger than its own; arranged in the same order of super-
position one upon the other; exhibiting similar characters
and structure, and carrying the same mineral wealth. As
geological truth depends upon the comparison of all like
facts affecting a given case, the geologist of Pennsylvania
must make himself familiar with the geology of the whole
Atlantic seaboard and the whole Mississippi valley; and he
will often find the solution of his own local problems five
hundred or a thousand miles beyond the border of his own
24 GEOLOGICAL SURVEY OF PENNSYLVANIA.
state. On the other hand the geology of New York, of
Ohio, of Maryland, of Virginia, of West Virginia, of Ken-
tucky, gets a still stronger reflected light from investigations
pursued for fifty years in Pennsylvania, where all the great
formations between the fundamental rocks and the coal
measures are in a more complete series, and at their greatest
known thickness. In this respect our state, small as it is in
relative area to the whole Appalachian region, is in fact a
standard of comparison, and occupies in geology as in
politics the position of the keystone in an arch. The
reason for this will be explained hereafter; at present it is
only needful to eni'orce the fact, and to stim ulate the imag-
ination to its proper comprehension, namely, that our geo-
ology is not local but general; that the rock formations of
one county of our state are not confined to that county, but
extend in immense sheets, with practically the same char-
acter, and lying upon one other in the same order, beneath
the surface of many of the other counties of the state, and
also of extensive regions of neighboring states; forming in
fact successive floors beneath nearly the whole United
States; sometimes rising to the surface, so that their edges
can be examined along lines and belts of greater or less
length; and sinking again to depths of several miles, where
it is to be presumed that their nature is unchanged; and
this presumption is the sole basis, but a practically sound
and reliable basis, for the little knowledge which we
possess of the earth's interior.
The three dimensions of length, breadth and thickness
then applies in practical geology to every rock formation.
(1) To the length of its outcrop, which (in Pennsylvania)
runs in a northeast and southwest direction; (2) to the dis-
tance which it extends underground from southeast to
northwest before it rises again to the surface in New York
or in Ohio; and (3) to the number of feet, or yards, or
hundred yards of its thickness as measured from its bottom
bed to its top bed, wherever it appears at the surface.
These are its three elements of size and quantity; and with
these three elements all the measurements and calculations
of practical geology are accomplished. If the slope (or
GEOLOGICAL DIMENSION. 25
angle with the horizon) at which a formation sinks into the
underground and rises again to the surface be carefully
observed, it becomes possible, and is usually an easy matter,
to estimate with truth its bulk or solid contents, the num-
ber of square yards or tons which it contains, and its dis-
tance beneath the surface at any given point where it may
be desirable to bore a well or sink a shaft to work it.
This is the first business of the geologist, and it is more
successfully pursued than people imagine, for it proceeds
upon the well-established application of geometrical rules
for the treatment of the length, breadth and thickness of all
solid bodies, rules that are invariable.
If rock formations were absolutely regular in their
shape, of equal thickness everywhere, this practice of geol-
ogy could be conducted without the least chance of mis-
take, and business men might depend with absolute re-
liance on the assertion of a competent geologist that a cer-
tain rock formation would be struck at such and such a
depth. But the case of a perfectly regular rock formation
is one of the rarest in nature. Not only every bed of
limestone, sandstone, shale, clay, coal or iron ore varies
in thickness within its own particular limits of variation,
but every group of beds, and every formation composed
of groups of beds, thickens in one direction and thins in
another, or thickens and thins alternately and irregularly
throughout its whole extent. So that, were it not for the
many times and places at which rock beds rise to the sur-
face to be measured again and again, these irregularities
would present an insuperable obstacle to the accurate prac-
tice of geology. In this respect the folded structure of all
middle Pennsylvania gives to our study of its geology an
immense advantage, and makes our knowledge of it ex-
tremely accurate. But where the whole series of forma-
tions lie entirely flat, and only the highest members of the
series can be seen at the surface, as throughout western
Pennsylvania and the greater part of the Mississippi basin,
tjiey completely conceal their underground irregularities of
thickness and quality. The only knowledge we can then
obtain of such irregularities must come from a comparison
of the records of well borings.
26 GEOLOGICAL SURVEY OF PENNSYLVANIA.
The exact number of wells bored in western Pennsyl-
vania is not known, but it must exceed 50,000. Many of
them have gone down only a few hundred feet, many more
are 1,000 feet deep, few reach 3,000, and the deepest, the
experimental borehole of Mr. Westinghouse, at Pittsburgh,
and the wells at Erie, Franklin, and Wheatland are respec-
tively 4,685, 4,460, 3,880, and 3,484 feet deep. Had the re-
cords of all the wells bored since 1859 been carefully kept and
the character and thickness of every rock stratum been ac-
curately observed, our knowledge of the underground geo-
logy of western Pennsylvania might be considered perfect.
As it is, nine-tenths of this knowledge has been lost. But the
one-tenth which has been rescued, taken in connection
with the innumerable outcrop exposures along river cliffs
and in ravines, is quite sufficient to make the geology of
that half of our state more accurate and reliable than the
geology of any part of the known world ; that is to say, to
the depth of about a mile. All the underlying formations
which only outcrop in middle Pennsylvania, and the great
crystalline floor-rocks which outcrop in southeastern Penn-
sylvania, are absolutely unknown in western Pennsylvania.
The expression absolutely unknown is true indeed only
in its precise sense. Probabilities are of every grade
of force, and sometimes rise nearly to the level of cer-
tainties. When eye-witnesses cannot be obtained, circum-
stantial evidence will in many cases prove sufficient for
conviction. If the head of a nail is seen on one side of a
board and its point projects from the opposite side, no
reasonable person would think it necessary to split the
board to see if the nail went through from the head to the
point. If the Gorniferous limestone formation, No. Villa,
which runs along the foot of the Bald Eagle mountain
for a hundred miles, from Muncy, past Williamsport, Lock
Haven, Milesburg, Tyrone City, AltoonaandHollidaysburg,
to Cumberland, in Maryland, and so on south, as a contin-
uous formation, descending vertically, or dipping steeply
north west ward, as if to go under the Allegheny mountain
if this limestone makes its appearance in a similar outcrop
along ihe Mohawk valley, in the State of New York, and
GEOLOGICAL DIMENSION. 27
keeps on in a nearly straight line westward to Niagara
Falls, reappears on the southern shore of Lake Erie near
Cleveland, and runs south through the State of Ohio to the
Ohio river above Cincinnati, and so on across Kentucky into
Tennessee, no reasonable man can refuse to believe that it
underlies, in a practically unbroken sheet, the whole region
enclosed between these two lines, and must surely be struck
by every oil well if the drilling goes deep enough.* It is for
the geologist to calculate what that depth would be at any
given point in the region ; and this he could do with math-
ematical certainty were the overlying formations perfectly
regular in thickness. Since they are not thus regular,
some law of irregularity must be discovered, and this can
only be done by measuring the interval between the Cor-
niferous limestone and some coal bed or limestone at the
surface, on the two edges of the region, the one in middle
Pennsylvania, the other in central New York and central
Ohio.
Such measurements have been made and repeated
until a pretty accurate average interval has been obtained
on each of these lines of outcrop. The difference between
them is so great that no better example of the irregularity
of our formations could be selected.
The Devonian and sub-Carboniferous formations in Ohio
measure, all told, only 1,175 feet; in Erie and Crawford
counties, 3,000' ; in Clinton county, 9,274' ; in Blair county,
10,909' ; in South Huntingdon, 11,546' ; at Cumberland, in
Maryland, 11,510' ; at Catawissa, in Columbia county,
12,212' ; on the Susquehanna river, above Harrisburg,
16,285' ; on the Schuylkill river, between Pottsville and
Schuylkiir Haven (they stand vertically) 20,000' (?) ; on the
Lehigh river, in Carbon county, 15,970' ; at Broadheadville,
13,550' ; at Stroudsburg, in Monroe county, 13,000', and at
Port Jarvis, along the Delaware river, in Pike county,
12.750'.
*It has actually been struck by three wells, the Presque Isle well at Erie,
at a depth of 1,400 ; the Wheatlaud well in Mercer county, at 3,384, and the
Con way well, nine miles below Franklin, at 3,880? But its southward dip
carries it down below the bottom of the Westinghaus well at Pittsburgh.
(See I 5, Carll's last Report, 1890, pages 72, 185, 188, 230.)
28 GEOLOGICAL SURVEY OF PENNSYLVANIA.
It is thus easy to see that formations VII, VIII, IX, X,
XI and XII, which occupy the interval, are thicker in
Pennsylvania than in Ohio, and as they are all deposits of
sand and clay in sea water, and are not only thicker, but of
a coarser character at the east than at the west, four con-
clusions may confidently be drawn, namely, (1) that the de-
posits came from the east and were floated out toward the
west ; (2), that the finer material was carried farthest out
to sea westward ; (3) that the difference of thickness had
little or nothing to do with the depth of water; and (4) that
the westward thinning must be gradual, if not regularly
graduated.
If now we could be sure that the westward thinning was
not only gradual, but regularly gradual, its rate would be
easily obtainable, and then the thickness of the interval
could be calculated with great precision, say for every ten
miles on a line drawn from Altoona to Pittsburgh, and from
Pittsburgh to Columbus in Ohio.
On such a supposition the depth of the limestone under-
neath Pittsburgh would be almost exactly 7,600 feet.
But here a disturbing element enters into the calcula-
tion. The outcropping edges of formations IX, X, XI and
XII can be followed up the West Branch Susquehanna for
many miles and all the way around into Ohio. They are
also brought up to view and can be measured in the mount-
ain gaps at Johnstown, at Confluence, at Blairsville,
Latrobe and Connellsville in southwestern Pennsylvania.
We can see how they all diminish in thickness from the
Allegheny mountain westward. We see also that the red
formations IX and XI diminish in thickness more rapidly
than the others, and become so thin before reaching the
Ohio line that they can hardly be recognized. This com-
plicates the calculation, so that we are forced to conclude
that the Corniferous limestone must lie at a depth beneath
Pittsburgh considerably less than the 7600' above stated.
The law of irregularity of ocean deposits illustrated by
this example on a grand scale holds good for all the sedi-
mentary formations of the world and makes itself felt in
the case of every individual bed in every formation, pro-
GEOLOGICAL DIMENSION. 29
ducing local thickenings and thinnings of every conglome-
rate, sandstone, shale or limestone bed; obliging the careful
geologist to repeat his measurements everywhere, and
restraining him from making too confident predictions of
what the boring tools are to find, or the precise depth at
which any desired bed will be struck. This will be ex-
plained more fully in describing the oil regions.
Returning to the subject of the westward thinning of our
formations, and reversing the direction, they are seen to
increase in thickness from the Allegheny mountain east-
ward to their final outcrop along the Blue mountain which
borders the Cumberland valley. In this middle belt of the
State we have uncommon opportunities for studying irreg-'
ularities of rock thickness. The strata rise to the surface
and sink again several times in a breadth of 50 miles; and
every time they rise for examination going southeast they
show themselves coarser and harder and thicker. If we
took in our examination only the direction from Altoona to
Chambersburg we might suppose these sediments to have
been produced by the destruction of the South mountains
of Fayette and Adams county; but the formations thin
away southward through Virginia into Tennessee, as they
do westward into Ohio; but in the other direction, north-
eastward, they increase in thickness toward the Catskill
mountains.
Comparative measurements made at Altoona, at Hunting-
don, in Perry county, along the North Branch of the Susque-
hanna in Montour county, along the Lehigh river in Carbon
county, and along the Delaware in Monroe and Pike
counties, must remove from every intelligent mind the popu-
lar and mischievous opinion that what is called a general
section of a series of rocks can be used for the practical
purposes of exploration by anybody who has it in hand,
whether he be a geologist or not.
30 GEOLOGICAL SUEVEY OF PENNSYLVANIA.
CHAPTER IV.
On General Sections.
It is necessary to explain clearly what this term "general
section " means, and it will then be seen that the common
practice of writers of geological reports and text-books in
placing a general section of the series of rocks which they
'are about to describe on the first page of their description
to enable their readers to keep in mind the order, character
and thickness of the rocks, while in one way it facilitates
the understanding of the description, leads in another way
to the most serious practical errors, whenever that de-
scription is taken as a guide to the special study of a re-
gion or locality.
A vertical section of a formation or series of formations
means a representation or drawing of a deep cut in the
earth from the surface downward, like the cut made by a
knife through a pile of buckwheat cakes at the breakfast
table. The character and thickness of each cake is thus
revealed and the order in which the cakes lie one upon the
other. If the various layers lie smooth and flat the section
shows it. If the layers be crumpled the section shows it.
If they differ in thickness anywhere the section shows it.
And if they have a general slope or inclination in one
direction, the lower layers rise toward one end of the sec-
tion, and the upper layers sink at the other end. It is
called a vertical section because it is made from the surface
directly towards the center of the earth.
A columnar section is merely a small portion of a verti-
cal section, showing the same facts of order, character and
thickness, by a narrow column placed at one side of the
printed page, drawn without any regard to the slope or
wrinkles of the rocks, and representing them as if they
were lying Jlat. The measurements are made at right
ON GENERAL SECTIONS. 31
angles to the beds, and are intended to express the exact
thicknesss of the several beds. It is evident that a hundred
such columnar sections may be made along the line of any
one vertical section; but that where the beds of a general
section are very regular one columnar section will be
enough to show their character, order and thickness along
the whole line. If, however, the rocks of a vertical section
be variable in character and thickness then a dozen or more
columnar sections will be required to exhibit these varia-
tions. Yet many geologists are satisfied with one, and the
readers of their reports and consulters of their text-books
are left to gather the nature of such irregularities from
descriptions of them in the text.
Now, what is true of one vertical section is true of all.
The line along which any vertical section is made is selected
by the geologist where it can be best studied in his district;
where a river has exposed the rocks for a mile or miles;
where railroad cuttings, lines of quarries, ore banks, mine
shafts or oil borings furnish him data for his measurements.
Such sections are of the greatest value, and are in fact the
foundation of all accurate geology. But these natural lines
of section do not often run in the most convenient direction;
run sometimes diagonally across the strike and dip of the
formations. The} 7 must be swung around to cross them at
right angles, if the true structure of the district is to be
exhibited. Consequently the geologist must make as
many such sections as possible in all parts of the district.
Some will be short and some long according to circum-
tances. To represent the whole geology of the district
he must put them together. He constructs thus what he
calls a general vertical section, and gives that as expressing
a summary view of the geology of the whole district. This
summary view will certainly give some general idea of it.
But a general idea of the geology of a district, however
good it may be, will be mischievously bad in one respect,
in that it will lead people who are not judicious field geol-
ogists to believe that that general section represents accu-
rately the geology of each and every portion of the district.
They will act on that assumption. They will apply that
32 GEOLOGICAL SURVEY OF PENNSYLVANIA.
general section to the discovery of minerals in parts of the
district where local facts do not correspond at all to the
general section. In fact nothing has tended more to bring
into popular disfavor the work of field geologists than
the serious embarrassments to which laymen have been sub-
jected in trying to apply the general section of a district
to some special locality in which they are personally in-
terested.
What has just been said has greater force in respect to
general columnar sections, which are intended to furnish a
quick and easy key to the order, character and thicknesses
of the rock-beds of a district. Even in the hands of an ex-
perienced geologist such general columnar sections are
dangerous tools to work with. They impose upon the im-
agination, and through the imagination upon the reasoning
faculty. They seem to reveal clearly what in fact they
conceal ; they mystify it, distort it, and change the truth
into positive error. They give the impression of regularity
in geology; whereas irregularity is the only law of geology
which can be called absolutely universal.
Even the experienced geologist is strongly tempted
to recognize a general columnar section as true at every lo-
cality. Only with an effort can he keep in mind that it is a
fiction, a construction, not a reality; a generalization; a
sort of dressed up official representative of thousands of
facts for which it speaks, but the various natures of which
it cannot correctly express. If one of the beds of any such
columnar section happens to be 20 feet thick at one end of
his district and 100 feet thick at the other end ; or, if it be
found to measure 20 feet at one point and 100 feet at an-
other even if these two figures be known to represent the
thinnest and thickest sizes of that bed within a given dis-
trict the columnar section will either say that the bed
varies from 20 to 100 feet, or it will say that its average
thickness is 60 feet. These are the two plans ordinarily
adopted in constructing a columnar section ; but they do
not relieve it of its mischievous character. For in the first
place there may be places underground to which no one has
had access where the bed may not exist at all. or where it
ON GENERAL SECTIONS. 33
thickens to 200 feet. Should a shaft be sunk or a borehole
drilled at such a point the general section is at once dis-
credited, and even whatever value it has will be denied.
But even if the geologist has been able to discover the
greatest thickness which the bed has anywhere, and its
thickness at that place amounts to 100 feet, it may be an
exceptional and purely local fact. Perhaps the bed
throughout the district varies little from 20 feet. To say
then in the columnar section that the bed varies from 20
feet to 100 feet gives a wholly false and unpractical de-
scription of it. If the second plan be adopted and the
average of 60 feet be marked on the edge of the column, it
becomes a false guide everywhere in the district, for there
may not be a single locality where this average of 60 feet is
realized.
What, then, is to be done? Shall there be no attempt
made to exhibit in the form of a column the order, char-
acter and /thickness of the rock formations of a district \
Shall the reader be left to manufacture his own ideas of it
from a confused mass of detailed descriptions in the text of
the report ? If he be thus left to his own devices he will
undoubtedly construct some general columnar section for
himself, and it will probably be a worse one than that which
the wise geologist has discarded.
There is a plain road out of the difficulty. A typical
columnar section should be substituted for the so-called
general columnar section.
Among the many local columnar sections which the geol-
ogist constructs (along his numerous lines of vertical sec-
tion), each one giving the precise facts at the place where
they present themselves to the eye for examination and to
the hand for measurement, there will always be one or an-
other more precise and more complete than the rest, show-
ing more distinctly the order, character and thickness of the
beds of the district, arid as accurate in its statement of the
facts as any of the rest. 'Such a columnar section, vouched
for in all of its details, and marked with the name of the
locality where it was studied by the geologist and can be
studied by any number of observers who choose to verify
3
34 GEOLOGICAL SURVEY OF PENNSYLVANIA.
the accurateness of his observations such a columnar sec-
tion, rightly called typical, is at the same time good
authority and of practical value. It leaves nothing to the
vague imagination. It is a reality to be depended upon.
It will serve as a useful guide. It stands only for what it is
worth. It makes no pretensions to general truth. It says
nothing respecting the stratification or structure at other
localities in the district, being only one of many, all differ-
ent from each other; and it can be referred to in explanation
of similar appearances not so well exposed to examination.
Above all, it will enforce upon -the mind of everyone who
uses it for comparison with other local columnar sections
that law of irregularity or variability on which the genius
of geology must forever insist, as the first to be recognized
and profoundest to be felt of all the laws of our science a
law that cannot be too often or too earnestly inculcated a
law both of the highest theoretical and the most real prac-
tical character, governing both our calculations respecting
the outspread of continental formations and the minutest
details of our mining operations.
THE APPALACHIAN SEA. 35
CHAPTER V.
The Appalachian Sea.
The arrangement of land and sea upon the surface of the
globe, with which geography makes us familiar, appears to
the human mind to be fixed and unchangeable. The relig-
ious traditions of mankind have taken this for granted and
explained the creation accordingly. But this is not a fact.
By the fossil forms of many extinct animals and vegetable
creations embedded in the rocks of all ages, it appears that
all continents have been formed beneath the sea, and have
emerged from it into the air. By the way the continental
fossiliferous formations lie one upon another it appears
with equal plainness that the lands have emerged and
been submerged alternately many times in the course of
the history of the world. But when the bottom of the sea
is lifted into the air the water which covers it flows away
from it, lifting the general sea level of the world in propor-
tion to the amount of land which has become uncovered.
The lifting of the general surface of the sea resubmerges
lands which were previously out of water. The crust of
the earth has been subjected in all geological ages to such
movements, and such movements are going on still; move-
ments both upward and downward. They are not upward
movements of the land and downward movements of the
sea bottom, but alternate upward and downward move
ments of both the dry lands 'and of the ocean bottoms.
The upward movement of a continent draining its edge,
lifts the sea level and submerges the edges and low-lying
plains of other continents. The downward movement of
one continent drawing the ocean over its low-lying lands,
lowers the sea level and causes an apparent elevation of
other continents; but the elevation is only apparent; the
ocean coast is extended outward by the fall of the sea level;.
36 GEOLOGICAL SURVEY OF PENNSYLVANIA.
submarine banks like those of Newfoundland and off the
Alaskan coast, are left like great islands exposed to the air
and ready to receive the seeds of a new vegetation, and the
immigration of new races of animals to feed upon them.
For the same reason, whenever the bottom of the sea has
been lifted there has been a rise of the sea level and an
overflow of the lowlands of all continents. On the other
hand every downward movement of the earth crust beneath
the ocean has lowered the sea level and drained the coasts
of the continents. It is a geological speculation unsup-
ported by sufficient evidence that the oceans have always
been oceans, and that the ocean bottoms have always been
descending. There is sufficient evidence to the contrary;
and such evidence is afforded in the clearest manner by the
geology of Pennsylvania. For many ages the crystalline
floor kept going downward, draining the sea water from the
rest of the surface of the world and exposing to the air more
and more of the - coasts of then existing continents. At
first the downward movement, if not sudden, was relatively
swift, and a deep ocean was early established along that
part of 'the earth's surface now occupied by our Atlantic
states ; but this is not certain.
This ocean first received the Cambrian sediments, and
afterwards the Silurian, Devonian and Carboniferous. Its
original depth may be imagined from the fact that on top
of 15,000 feet of Cambrian beds lie in middle Pennsylvania
6,000 feet of lower Silurian limestone (regarded by most
geologists as a deep sea deposit)* and 6,000 feet of fine sand
and mud-slate, on top of which lie 30,000 feet of Upper
Silurian, Devonian and Carboniferous strata.
Now if this Appalachian ocean had been established at
once, by a sudden drop of the crust of the earth to a depth
sufficient to receive all these Cambrian, Silurian, Devonian
and Carboniferous strata, that is to a depth of 7 or 8 miles,
the general sea level of the world would have been lowered
many hundreds of feet. But we are forbidden to suppose
a sudden movement on so grand a scale. But whether
*Bnt of this assumption I ain very doubtful, as will appear in the Chapter
on Formation No. II.
THE APPALACHIAN SEA. 37
quick or slow, such a downward movement of one part of
the earth's crust should in all probability have entailed as
a consequence a corresponding elevation of other parts of
the surface of the globe, parts of the then existing ocean
bottoms, as well as parts which were already dry land.
There is nothing but a theory to oppose the supposition
that what is the Atlantic ocean now (or a portion of it) was
in all Palaeozoic time a continent exposed to the erosion of
the rainfall, supplied with rivers, and bestowing the waste
of its rocks in the Appalachian sea. Its smaller rivers, de-
scending rapidly from its highlands, would supply conglo-
merates; its larger rivers meandering from its back
countries, with longer and more gentle currents, would
supply the slates and clastic limerocks.
It is, of course, impossible to decide between the oppos-
ing probabilities of a faster or a slower rate of the down-
ward movement which established the Appalachian sea
basin. All we can say is that the great limestone deposits
are very early ; and supposing them deep sea deposits, we
must conclude that the establishment of a deep Appala-
chian sea basin was of early accomplishment; that the
downward movement was at first comparatively rapid; and
that it continued (perhaps more and more slowly) to the
end of the coal age.
The two thoughts which are here fundamental to the
knowledge of our Pennsylvanian geology are these: (1)
that what was the continental area of crystalline rocks
became by the downward movements of the earth's crust
an Appalachian sea basin of unknown depth, and was in
the course of the Cambrian, Silurian, Devonian and Car-
boniferous ages so completely filled up as to become at last
a great marsh or archipelago of marshes, bearing the vege-
tation of the coal; and (2) that this whole area was then
lifted high into the air; that a corresponding contempo-
raneous down ward movement established the Atlantic ocean
or parts of it, as the thrust which elevated the Appala-
chians came from that direction; and that submergence of
other lands of the world must have been occasioned by the
general rise of the sea level.
38 GEOLOGICAL SURVEY OF PENNSYLVANIA.
All this took place in the Palaeozoic times, that is in the
first great geological age of the world of animal and vege-
table life. The coal measures, which were the last deposits
in the Appalachian sea, taken as a whole, is inconceivably
ancient and remote from the present day.
A second division of geological history then succeeded :
the Mesozoic or Middle age of animal and vegetable life.
Then came the Kainozoic (Cenozoic) or New world of
animal and vegetable life, ending with the appearance of
man.
Each of these three ages of the world's geological history
has had its own series of continental elevations and depres-
sions; its invasions of the continent by the ocean and the
reappearance of land surfaces on the retreat of the water
into the sea basins; its own peculiar sequence of sediments
brought by rivers {and deposited in the sea, all of them
preserving in their mud and sand layers the waste of suc-
cessive forests, and the dead remains of genera and species
of animals.
All the greater mountain ranges of the world are com-
posed of such sedimentary rocks, which have been lifted out
of the ocean into the air in successive ages since the de-
posit of our coal beds, and mostly in Mesozoic and Kainozoic
times.
Movements on so grand a scale must have altered mate-
i;ially the relation of lands to seas, modifying more or less
the geography of the whole earth's surface. Therefore, I
find it hard to believe that oceans have always been oceans,
and continents, continents, even if other facts than those
alluded to above were not known to prove the opposite.
THE NAMES OF THE FORMATIONS. 39
CHAPTER VI.
The Names of the Formations.
Everything has to have a name. It makes very little dif-
ference what name is bestowed upon it, provided that name
be generally accepted and is different from the name of
anything else, so that the name shall always stand for that
one thing and for nothing else. In science great pains have
been taken to invent names which signify the character, or
some characteristic feature, of the nature of the thing
named. But in a science like geology, which includes sev-
eral sciences, structural geology, chemical geology, fossil
geology (paleontology) and economical geology (mining
engineering, etc.) different geologists will each one look
upon a rock formation with that particular interest which
it has for his special studies or work, and will wish to name
it accordingly. Geologists in different regions will give dif-
ferent names to the same formation, each affixing to it the
title of some locality where he finds it best exposed to view,
most easily studied, of greatest size, or most valuable for
the community. Geologists of different countries, speak
ing different languages, have given many different names to
the same stratum or series of strata. All this is inevitable.
No international congress of geologists can either hinder or
help it. The confusion arises out of the multiplicities and
irregularities of nature itself. Those who wish to profit by
geological investigations and discoveries must submit to the
burden of geological nomenclature and learn all the names,
even if they choose to use qnly some. It is impossible, to
macadamize or asphalt the highways and byways of
knowledge.
All our state geological surveys have invented names for
some of their formations, and for others have borrowed
names already given to them in neighboring states. Geo-
40 GEOLOGICAL SURVEY OF PENNSYLVANIA.
logical formations care nothing for geographical lines
established by king's charter or acts of congress. They
pass underground from one state into another. The geology
of southern New York is exactly the same as that of north-
ern Pennsylvania. The geology of northern New Jersey
passes on across middle Pennsylvania into Maryland and
Virginia. Eastern Ohio and western Pennsylvania share
with West Virginia the same beds of coal, limestone and
iron ore, the same oil and gas sands. The formations ex-
posed on the Juniata are exposed on the Potomac, and their
outcrops extend to Alabama. The Brown sandstone and
red shale belt of Bucks, Montgomery, Chester, Lancaster,
York and Adams counties is continued to the Dan and
Deep rivers of North Carolina in one direction, and up the
Connecticut valley into Vermont in the other direction.
The Philadelphia gneisses and mica schists pass on without
break through Delaware, Maryland and east Virginia as
far as Georgia. The South mountains of eastern Pennsyl-
vania are the same as the Highlands of New Jersey and
New York ; the South mountains of southern Pennsylvania
are the same as the Blue Ridge of Virginia.
These facts are positively known to all geologists now ;
but they were only suspected to be possibly or probably
true by geologists sixty years ago, when the principal state
surveys were set on foot. Hastily to give the same name to
a series of rocks in two different states which might turn
out on examination to be two distinct series would have
made a great embarrassment ; and an example of this is af-
forded by the employment in our Pennsylvania reports of
the name "Potsdam sandstone" borrowed from Dr.
Emmons' survey of the Champlain district in northern New
York, to designate the "White Spot" rock overlooking
Reading, Chicques rock at Columbia, the quartzite beds at
Mt. Holly Springs and Mont Alto in Cumberland and
Franklin counties, and the North Valley hill rock at
Downingtown and Norristown; for it is now doubtful if all
or any of these have right to that name.
A still more flagrant instance is afforded by the old and
standing controversy over the name Taconic System, a
THE NAMES OF THE FORMATIONS. 41
name which may justly be called the Nightmare of Ameri-
can Geology, from which, however, we are happily almost
awakened.
For fear of thus hampering their surveys with names that
might become popular and yet' be absolutely false and
worse than useless the state geologists of Pennsylvania and
Virginia, the distinguished brothers Henry D. and William
B. Rogers, refused to accept the names of the formations
adopted for New York by the four principal geologists of
that state, Mather, Emmons, Vanuxem and James Hall,
and adopted a plan of numbering the great formations ac-
cording to their order of superposition from below up-
wards; a series of numbers which of course would never
change, and for which distinctive names might be after-
wards substituted. These numbers, from I to XIII (after
wards increased to XVII) only applied to the rock forma-
tions of three-fourths of the state, Silurian, Devonian and
Carboniferous. The earlier rocks of the Crystalline region,
and the later rocks of the New Red or Brownstone region,
all of them in southeastern Pennsylvania, were left unnum-
bered. This numbering was accomplished in 1836 and
1837.
Between that time and 1858, when the " Geology of Penn-
sylvania" was published, the brothers Rogers, who were
poets as well as geologists, devised a series of names which
they proposed to substitute for the series of numbers, and
for all other names applied by foreign and domestic geolo-
gists to the Palaeozoic formations, considered as successive
deposits made in one long, great geological day of time ; a
day divisible into four portions, before and after sunrise,
before and after sunset; the day in which the Lower and
Upper Silurian, Devonian, Carboniferous systems of the
English geologists were deposited. But the Coal Measures
belonged to the night and received no name ; or, rather,
were allowed to retain that popular appellation, being sim-
ply Coal Measures.
No. 1, at the base, also, was simply named the Primal
sandstone; Nos. 2, 3, Auroral and Matinal ; Nos. 4, 5, 6,
Levant (sunrise), Scaletut and Premeridian; No. 7, M&ri-
42 GEOLOGICAL SURVEY OF PENNSYLVANIA.
dian or noon; Nos. 8, 9, Cadent an&Ponenl (sunset) ; Nos.
10, 11, 12 Vespertine, Umbral and Serai.
All these names, except three, are long since forgotten.
No geologist has accepted them as useful. But, curiously
enough, the people of western Pennsylvania, led by the
coal prospectors of the Allegheny mountains, adopted the
three exceptions, and still speak of the Vespertine sand-
stone No. X, the Umbral red shale No. XI, and the Serai
conglomerate No. XII. Some geologists have, therefore, em-
ployed them in local reports; and they will continue to be
used occasionally instead of the newer 'names: Pocono
sandstone, Mauch Chunk red shale, and Pottsmlle conglo-
merate.
When the geological survey of the state was reorganized
in 1874, and county reports began to be published, it was
needful to adopt names for the rock deposits. The old
numbers were not precise enough; the fanciful names of
1858 had been universally ignored; the New York names
had come into universal use. These last therefore were
applied to the formations in Pennsylvania, and others of
the same geographical character were added at the end of
the list where Pennsylvania had higher strata than any in
New York.
No. 1 was called Potsdam sandstone.
No. 2 included the Calciferous sandstone, Chazy and
Trenton limestone.
No. 3 included the Utica and Hudson river slates.
No. 4 included the Oneida conglomerate and Medina
sandstone.
No. 5 included the Clinton, Niagara and Salina shales.
No. 6 was the Lower Helderberg limestone.
No. 7 was the Oriskany sandstone and Caudagalli grit.
No. 8 extended from the Corniferous and Marcellus up
through the Hamilton, Genessee, Portage and Chemung.
No. 9 was the Catskill or Old Red sandstone.
No. 10, not being named in New York, although it forms
the peaks of the Catskill plateau, received the name Po-
cono gray sandstone.
No. 11, Mauch Chunk red shale.
THE NAMES OF THE FOKMATIONS. 43
No. 12, Potts ville conglomerate.
No. 13, Allegheny river coal measures.
No. 14, Pittsburgh (Lower Barren) measures.
No. 15, Monongahela river coal measures.
No. 16, Washington county group.
No. 17, Greene county (Upper Barren) measures, the
highest Palaeozoic strata to be found in Pennsylvania, and
possibly belonging to the last or Permian age of that era
in geological time.
Names given by the assistant geologists of the state
survey to sub-divisions or important local beds in these
formations will appear in the chapters devoted to their
description.
The terms Azoic, Eozoic, Palaeozoic, Mesozoic, Kainozoic,
have been already alluded to as designating the successive
grand geological ages of vegetable and animal life on the
planet. It is not intended in this book to use the first two
with any dogmatic sentiment, in view of the current con-
troversies on what I consider a very unimportant subject,
namely, the precise unification of geological nomenclature.
One name is quite as good as another provided it be known
to what it applies, and provided that it implies no false
description of character.
Azoic or No-Life rocks was a good term, first applied
by Foster and Whitney to the crystalline and semi-crystal-
line rocks of the Lake Superior region, to express the fact
that no relic of either vegetable or animal life had yet been
discovered in them. It was not intended to assert that
these rocks never had had fossil seaweeds or shells in
them, but merely that nonesuch had ever yet been discov-
ered in them. It is not only probable but proved that fossil
bearing sediments crystallize, and in doing so obliterate the
fossil forms which before crystallization must have been
visible enough. The term Azoic simply tells the fact that
no fossils have been found in them. The objection made
to it, that rocks of later ages may suffer this change and
lose their fossils is not practically a good one, and for this
reason, viz : that ninety-nine-hundredths of the Azoic
rocks belong to the oldest geological age we know anything
44 GEOLOGICAL SURVEY OF PENNSYLVANIA.
about; therefore Azoic is a very convenient name for the
oldest formations, whether they appear at the surface in
our southeastern counties, or lie at great depths beneath
the rest of the state.
Archcean is however a much better terra, invented by
Professor Jas. D. Dana, and adopted very generally,
almost universally, by the geological craft, because it
simply means the oldest rocks known, and passes by the
question whether they ever contained fossils or not.
Fundamental gneiss was the term preferred at first
by English geologists because it expressed the general
character of the crystalline consolidated floor on which all
other formations have been built up. But Dana's name
Archcsan has been gradually replacing the English name
even in England.
Laurentian, Sir W. E. Logan's name for the Azoic,
Archaean, Fundamental gneiss floor of the known geological
under- world, has been very generally adopted by American
geologists, and has been used in many of the reports of the
survey of Pennsylvania, especially in Prof. Prime's reports
on Northampton and Berks counties, Mr. C. E. Hall's
reports on southern Bucks, Montgomery and Delaware
counties, and Dr. Persifor Frazer's reports on Chester, Lan-
caster, York and Adams counties. The mountains of the
Lower St. Lawrence, Labrador, Canada, and the Adiron-
dack region of northern New York, show the floor rocks of
the world on the grandest scale.
Pre-Cambrian is another term for the same azoic, archsean,
fundamental, Laurentian rocks, adopted by conservative
geologists who recognize how little we know of them, and
how uncertain are the identifications of them in the isolated
and far-separated regions where they appear at the present
surface of the globe. For this term merely states that they
were in existence when the first Cambrian or Eozoic sedi-
ments were deposited upon them in the earliest seas. In
this sense Pre-Cambrian means all rocks older than or be-
neath the lowest Cambrian beds which contain fossils. But
by other geologists it is used in another sense, namely, to
signify formations which show themselves rising to the sur-
THE NAMES OF THE FORMATIONS. 45
face from beneath the Cambrian, and which yet may not be
as old as the Laurentian, but intermediate between the
Laurentian and the Cambrian. If they contain fossils
they should be included in the Cambrian. If they do not,
they are Azoic rocks, but yet may not be Laurentian.
The Huronian system, lirst studied by Murray on the
north shore of Lake Huron, and so called by Logan and
Hunt, of the Canada survey, was supposed to hold such in-
termediate place. But Irving and A. Winchell have appar-
ently proved that only the lower portion of it is Pre-Cam-
brian, and the upper portion may be Cambrian, although
no fossils have yet been found in it by which alone its Cam-
brian age can be established. In Report E of the Pennsyl-
vania survey Dr. T. S terry Hunt has used this name
Huronian in describing rocks in Adams county; and Dr.
Frazer's sections of the South mountains of Cumberland
and Fayette counties give them a Huronian aspect. On the
other hand, Walcott's Cambrian quartzites seem to be well
represented in the Mt. Holly (Papertown) gap, and else-
where between that and the Maryland line. But no fossils
(except ScolitTius) have as yet been found in the South
mountains ; probably, or perhaps, for want of observers suf-
ficiently disciplined by the study of Cambrian areas else-
where to detect them. The Green Mountain rocks of Ver-
mont are called by T. S. Hunt Huronian. Of the White
Mountain hornblendic gneisses and mica schists he makes
his Montalban system, and identifies it with the Philadel-
phia belt ; Montalban being after and above Huronian.
See Report E, page 241.
Eozoic rocks are those which show by fossils the dawn
of life on the planet. It is a convenient phrase which
means nothing definite and it is synonymous with the
term Cambrian, although the Eozoon canadense is called a
Laurentian fossil. But C. E. Hall asserts that he can prove
that the strata which contains this oldest of all supposed
animal remains in the rocks of the'earth really belong to
post-Laurentian times. At all events, with the possible ex-
ception of the Canadian Eozoon canadense, the earliest ani-
mal remains are the trilobites and shells of the Lower Cam-
brian (once called Taconic] rocks.
46 GEOLOGICAL SURVEY OF PENNSYLVANIA.
Cambrian is Sedgwick's English name for a great series
of deposits in Wales, Scandinavia, Bohemia, Spain and
elsewhere, which have been admirably studied by Walcott
and others in eastern New York, eastern Massachusetts,
New Brunswick, Newfoundland, Georgia and the Rocky
mountains. Its three divisions of Lower, Middle and
Upper are characterized by what are called the Olenus,
Paradoxides, and Olenellus faunas, or groups of trilobites
mixed in with sea shells of many kinds, sponges, worms,
sea weeds, etc. With the old controversy between Sedg-
wick and Murchison respecting the limits of the Cambrian
and Silurian systems, practically settled by the publica-
tions of the geological survey of Great Britain, we have
nothing to do. And as little now with the equally pro-
tracted and ill-natured controversies over Dr. Emmons'
Taconic system, now happily ended by discoveries which
turn that unfortunate system upside down and distribute
its members among the Silurian and Cambrian formations.
The same fate has befallen Logan's Quebec group. Neither
of these too famous names appear in the reports of the
Pennsylvania survey, as far as I can now recollect, except
that certain fossils in P. 4 are quoted as occurring in the
latter.
Palceozoic ropks are those which contain the remains of
the ancient living beings of the world, vegetable and ani-
mal, from the Cambrian sea weeds, sponges, worms and
trilobites up to the land plants, shells and reptiles of the
Coal age. If anyone pleases he may merge the Eozoic in
the Palceozoic, and begin the system at the bottom of the
Cambrian sediments, calling the whole Palceozoic. Cam-
brian is a more definite term than Eozoic, and quite as con-
venient. The fewer names the better. Until their discov-
ery by Walcott three years ago in the Trenton limestone
of the Colorado, fishes were supposed to have come into ex-
istence in the Upper Silurian times. New discoveries are
constantly carrying back the first appearance of one or an-
other family of living things to remoter and remoter times.
No one has a right to say how early in geological history
vegetables and animals appeared. "The dawn" of life re-
THE NAMES OF THE FORMATIONS. 47
cedes, farther and farther into the past. The word Eozoic
is becoming useless ; the term Palaeozoic will always be
sufficient to embrace it.
Silurian rocks, originally studied by Murchison in
Wales, whence their name, and since then in most of the
countries of the world, were early recognized in New York,
and there classified (in ascending series) as Potsdam, Cal-
ciferous, Chazy, Trenton, Utica, Hudson river, Oneida,
Medina, Clinton, Niagara, Salina (at first Onondaga] and
Lower Helderberg, corresponding to the Pennsylvania num-
bers I to VI.
Devonian rocks, first studied by De la Beche and Mur-
chison in southwest England, and afterwards in Scotland
and other parts of the world, received in New York the
sub-division names (upwards) Oriskany, Upper Helder-
berg, Marcellus, Hamilton* Genesee, Portage, Chemung
and Catskill, corresponding to the Pennsylvania Nos.
VIII and IX.
The Carboniferous formations in Pennsylvania are (in
ascending order) Pocono ( Waverlyin Ohio), Mauchchunk,
Pottsville, Allegheny, Pittsburgh, Mono7igahela, Wash-
ton county and Greene county groups, the last two being
awkward names for the highest palseozoic rocks in the state.
An unknown additional quantity of beds having been re-
moved by erosion, the original topmost or last deposits of the
Carboniferous series are unknown. This is the same as
saying that the exact date at which the Appalachian sea
was dried by the elevation of the Palaeozoic continent into
the air is not indicated by any now remaining layer or
layers of rock in the region of southwest Pennsylvania, or
elsewhere in the state. If the upward movement took
place within the limits of the Permian age of Europe, then
the highest strata of Greene county may be called rem-
nants of the Permian formation. But geologists on both
sides of the Atlantic are disposed to classify the Permian
strata as the last of Paleozoic age, and to begin the great
Mesozoic age with the Trias.
The Mesozoic or middle life time of the world's geological
history, as we know it on the surface, began with that vast
48 GEOLOGICAL SURVEY OF PENNSYLVANIA.
catastrophe which produced the United States as a contin-
ental area. He that is best acquainted with the phenomenon
will be the best convinced that it was a sudden or rapid
movement, a genuine cataclysm. The overthrust faults are
of themselves alone sufficient to prove it. A belt of par-
allel mountains, as high as any that now exist in South
America or Asia, rose into the air along a line extending
from the St. Lawrence to the Q-nlf of Mexico, passing
through Pennsylvania. The whole Appalachian sea was
drained off and became dry land, a continental area of coal
measures, much of which has since then been carried away,
but much still remains, constituting the extensive coal
fields of the present time. The whole rain water drainage
was reversed. The Palaeozoic river system which came
from the east disappeared, and a new Mesozoic river system
began to dissolve the raw continent and carry its undried
strata piecemeal eastward into the newly-created basin of
the present Atlantic ocean.
The Mesozoic age has three divisions, during which were
successively deposited the Triassic, Jurassic and Creta-
ceous rocks. These again are subdivided in Europe into
Bunttr, Middle Trias, Keuper, RhcBtic and Lias; Oolite,
&c.; Wealden, Oreensand and Chalk. With most of these
names Pennsylvanian geology has nothing to do. Some are
local English or German names. And many more names have
been invented for use in other countries of Europe, Asia
and Africa, where peculiar fossil plants and animals of
Mesozoic times have been collected and described; ferns of
a new style; trees quite different from those that made the
coal forests; crocodilian land reptiles; winged lizards, the
prototypes of birds; reptilian sea serpents; superb whorled
shellfish (Ammonites)^ small land mammals like kangaroo-
rats and ant-eaters; fish with pointed teeth of twisted fibre;
the earliest oysters, &c.
The Mesozoic age was probably as long as the Palaeozoic,
judging by the thickness and variety of its sediments, and
the succession of its living creatures. In Bucks and Mont-
gomery counties Mr. B. S. Lyman's survey makes out more
than 22.000 feet of regularly super-imposed strata, all de-
THE NAMES OF THE FORMATIONS. 49
posited in its earlier and middle divisions. To this must
be added the Cretaceous or greensand marl deposits of
southern New Jersey, which only appear in Pennsylvania
at the bend of the Delaware below Trenton.
New Red was the name (borrowed from the English) at
first given to the Mesozoic belt crossing the Delaware,
Schuylkill and Susquehanna rivers, and the Maryland state
line.
Trias is the name usually given to it in the survey re-
ports; and by this name the system, as studied by the
Hitchcocks in Massachusetts, by Cook in New Jersey,
and by Fontaine in Virginia, is now commonly known.
RlKKtic is the term adopted by Fontaine (in his U. S.
Geological Survey monograph report on the. fossil Mesozoic
plants of Virginia) by the use of which he wishes to make
more precise the sub-division of Mesozoic time in which that
vegetation flourished.
Newark formation is the name used by the New Jersey
Geological Survey, and adopted by the assistants of the U.
S. Geological Survey, for the Trias sandstone formation of
Pennsylvania.
The Lias and Oolite of Europe are not recognized in the
Atlantic seaboard region of North America.
The Cretaceous, on the contrary, is well represented,
but no chalk beds are known this side of the Mississippi river.
It contains the lower two of the three greensand marl beds
of New Jersey and Delaware, the third or uppermost being
placed in the Tertiary. Its lowest member (the English
Wealden] is called the Potomac formation, and its upper or
greensand member the Severn formation, by the U. S. geol-
ogists working in Maryland and Virginia.
The KAINOZOIO (Cenozoic) TERTIARY, Third, New Life age
of geological history, produced an equally vast and varied
series of deposits, named by Lyell Ei.cene, Miocene and
Pleiocene (to which was afterwards added Pleistocene] to
express the fact that the species of plants and animals now
living, all of them new, made their debut upon the scene in
tliedawn of this new third great day (Eo-cene tertiary}; be-
came more numerous in Mio-cene tertiary times ; most
4
50 GEOLOGICAL SURVEY OF PENNSYLVANIA.
numerous in Pleio-cene; and most of all numerous in the
Pleisto-cene. These names, except the last, are still in
common use, but only for purposes of vague and general
description, or in references where knowledge is not locally
precise enough. They do not much concern Pennsylvania,
a region out of water since Mesozoic times, and therefore
destitute of those Tertiary sediments which (with the Creta-
ceous) make the tide water plain of southern New Jersey,
Delaware, Maryland and other Atlantic and Gulf states.
Pamurikey (Eocene), Chesapeake (Miocene), Appomatox
(Pliocene ?), and Columbia (early Pleistocene), are names
given to Tertiary sub-divisions in Maryland and Virginia
by the U. S. Geologists. The PamunJcey represents the
uppermost (or third greensand marl) beds of New Jersey.
The Chesapeake diatom beds at Fort Monroe are 1,000 feet
thick. The Appomattox gravel loam formation is the same
as the Bryn Mawr (400' level) high gravel of the Delaware
county Report C 4. The Columbian terraces pass up the
river valleys of Pennsylvania and are connected with our
glacial deposits, which are usually designated, not Tertiary,
but Quarternary.
In the Tertiary age appeared shrubs and trees that
flower and fruit, and animals of sea and land that suckle
their young, herbivorous and carnivorous, man among the
number. When first mankind appeared is not known; nor
when the dog, the ox, the sheep, the horse, the elephant.
It has just become known that Leidy's fossil horse of Caro-
lina was not a modern horse. Mammoths and Mastodons
were not the modern elephant. No fossil ape agrees en-
tirely with man. Yet discoveries year by year have been
pushing back the proven existence of man into Tertiary
times. There is therefore less and less propriety in sep-
arating the age of man from the Tertiary (or Kainozoic)age
and calling it, as is so often done, the QUAKTERNARY or
Fourth age of the world. Yet this will still be used as a con-
venient term for expressing the state of things which now
exists, and be especially applied to alluvions, or river
sands and gravels and clays such as Philadelphia is built
upon.
THE NAMES OF THE FORMATIONS. 51
The Glacial Age, or Age of Ice, is a term which fre-
quently occurs in this and other geological literature of a
recent date. Its use began when, half a century ago, the
great Swiss explorer of the Alps, Louis Agassiz of Neuf-
ohatel, announced his theory that Europe had been covered
with a sheet of ice just previous to the creation of mankind.
When he settled as a teacher in Harvard College, Cam-
bridge, Mass., he showed that all New England had been
under ice. Since 1847 the phenomena of the glacial epoch
have been studied by Upham, Carll, Wright, Lewis, Cham-
berlin, Dawson, Whitney and a host of other glacialists,
over all North America ; and the southern edge of the ice
sheet, the terminal moraine of the continental glacier, has
been traced for over 2,000 miles from Cape Cod to Mani-
toba. Its course through Pennsylvania is mapped and
described with many illustrations in H. C. Lewis' Report
of Progress Z. The age seems to have been double, the
first ice sheet receding and the second ice sheet advancing,
with an interval of vegetation between the two. In Cali-
fornia man seems to have been living before the first
advance of the ice. In other parts of America man and
the mastodon lived together as in Europe and Asia man
and the mammoth lived together in glacial times.
The cause of the prevalence of ice in the glacial age is
still a matter of contention; but the facts have been verified
beyond controversy and are accepted by all. Many of the
details are still to be worked out; but the general theory is
well established.
Now granting that such physical operations as the
evaporation of the sea water and the condensation of snow
upon highlands, to form ice in favorable situations, have
been regular from the beginning of geological time, it is
reasonable to search for evidences of previous and far more
ancient glacial epochs ; and such evidences, in the shape of
moraine blocks and scratched rock surfaces, have been
found in England, in India and in South Africa. Prof. Kerr
thought he found such in his survey of North Carolina.
All these evidences are localized in the last Permian or first
Triassic rocks. None have been found in Pennsylvania;
52 GEOLOGICAL SURVEY OF PENNSYLVANIA.
and foe good reason. There must have been a glacial age im-
mediately following the rise of the great anticlinal mountains
of our state out ol the Appalachian sea into the upper
regions of the atmosphere to a height of more than five
miles above present sea level, and to a height of perhaps
eight miles above the bottom of the alternate synclinal
valleys. Even if the climate of the 40th parallel of north
latitude in the coal age was tropical, the tops of the uplifted
anticlinal ridges must have been immediately covered with
perpetual snow, like Killimanjaro under the equator in
eastern Africa, the volcanoes of Peru, and Mount Whit-
ney overlooking the valley of death in Arizona, where the
thermometer stands at 110 F. in the shade. The heads of
the synclinal valleys doubtless made good circuses for the
manufacture of neve ; and of course glaciers flowed down
the synclinal valleys, and produced mountain-meal and
moraines. The meal was not white like that made now
from Jurassic, Cretaceous and Tertiary slopes of the Alps,
but dark grey and red from the Carboniferous and Devon-
ian ; and therefore the deposits of Triassic age in Pennsyl-
vania, brought down by the Susquehanna and Delaware
from that ancient highland, are mostly red or reddish. But
the long continuance of erosion has reduced the highland
to its present level of only 1,500 to 2,500 feet above tide
level, and swept away every trace of that local glacial state
of things.
Alluvial deposits are those river gravels, sands and clays
which have been deposited in the now existing valleys,
mostly since the retreat of the ice, and up to the present
date.
HIGHLAND GNEISS. 53
CHAPTER VII.
The Earliest Archcean, Azoic, Highland, Laurentian,
Fundamental gneiss or crystalline schists.
In the beginning of time as known by the science of
geology, the heavens were as they are to-day; the planets
encircling the sun, comets coming' and going, the moon
a trifle nearer to the earth, the sun a little farther off but
shining with somewhat more fervor and brilliancy.
The earth was already in extreme old age, having long
before then shrunk almost to its present size and globular
shape, by slow condensation, from a gaseous to a liquid
state, and got itself encrusted with a rind of solid rock,
which no longer shone with a dull red light of its own, but
reflected into space the white radiance of the sun.
The surface of the earth was no longer hot enough to
keep all the water of the planet in a state of vapor in the
surrounding atmosphere; descending in local deluges of
sour rain to boil upon the rocks and dissolve apart their
mineral elements, sweep them into hollows, and there leave
them, while it sprang aloft as steam to rejoin the universal
canopy of cloud. All this had taken place before the
flrst age of which we have any geological monuments, and
is only known to God and Dr. Sterry Hunt, who has de-
scribed it magnificently in his Chemical Researches.
When the monumental history of geology commences,
the crust of the earth had become as fixed and rigid as
the attraction of the sun and moon and Jupiter would
permit. It still bent and groaned and quaked indeed, as
the globe turned on its axis beneath thier irresistible
influence; but now only enough to strain open great vol-
canic vents, from which flames and smoke and ashes were
ejected, to fall in beds of tufa over large areas ; and from
54 GEOLOGICAL SURVEY OF PENNSYLVANIA.
other apertures great streams of lava poured themselves
upon the surface of the lands, or spread themselves upon
the bottom of the sea. Earthquakes were then in the
common order of events, and changes of sea level rapidly
accomplished. The air was moist and murky, the ocean
warm, the continent a bare and rocky desert, ridged and
rugged, with no sign of future life. No sound disturbed
the silence of the air, except the noise of water-falls, of
rain, or breaking waves, the roar of a volcano, the crash of
a crumbling cliff, or the explosion of a descending meteor.
But snow had begun to cover the peaks of Alpine mount-
ain ranges, and old thousand- branched rivers raged
through chasms between them, fretting their sides into
valleys, and sweeping the rabble-rout of that perpetual
destruction into all low places where the waters lay eager
"to receive and spread it out in beds. There was no more
hurry nor appearance of confusion then than now ; only a
anore earnest, rapid and efficient operation of tearing down
t)n land and building up at sea ; for Nature was leveling
her grounds and getting ready to plant and house her
future progeny. Nor can we find out with all our search-
ing and calculation how many centuries or milleniums of
human and solar years that first great No-life age of purely
physical preparation lasted.
Of that Archaean, oldest, Azoic, or No-life age we know
nothing except the kinds of rock which bear its date.
These appear at the present surface of the earth only here
and there, in limited districts, far apart from one other, in
Canada and New England, in the Blue Kidge, in the Rocky
mountains, in Brazil, in Scotland and Scandinavia and
Bohemia, in the Ural mountains, in Upper Egypt, the pen-
insula of Mt. Sinai and elsewhere ; but so surrounded and
overlaid by the deposits of aftercoming ages that no con-
nected account can be given of their origin and general dis-
tribution; nor can the geography of that time be mapped
out ; not even where was land and where sea ; nor where
the mountains rose, nor where the rivers ran, nor the di-
rection of the great sea currents, nor the location of vol-
canic vents. So that nearly all that has been printed in
HIGHLAND GNEISS. 55
geological books respecting these things may be safely
regarded as pure speculation, and uncommonly daligerous
for any one to believe who wishes to gather only the
knowledge that is real, and prefers expectant ignorance to
any satisfaction to be drawn from unsubstantial opinions.
What is certainly known about the oldest rocks may be
set down in a few sentences.
First, that they underlie all the formations in which
appear traces of vegetable and animal life, and therefore,
that they constitute the underground bottom floor of all
countries wherever life-rocks occupy the surface
Secondly, that they differ from the life-deposits of suc-
ceeding ages by being crystalline instead of granular; as
loaf-sugar differs from ground sugar, or wheat from grist
or flour, or wood fibre from paper pulp, or a stone-slide at
the head of a river from the sand banks at its mouth. For
the life-rocks of subsequent times have been made out of
the frost-fractured and water-worn no-life rocks of the
ground floor of the world; and show this derivation in the
fact that the original crystals may still be detected, with
their points and edges worn off, and their prisms changed
into globules or rounded grains.
Thirdly, that they differ among themselves by the cir-
cumstance that some are coarsely crystalline (like the
porphyries and graphic granite), while others are so finely
crystalline (like many of the quartzites, felsites, diorites,
dolomites and micaceous gneisses) that their crystalline
constitution must be looked for with a magnifying glass.
Fourthly, that they differ among themselves in another
particular, namely, that some are plainly stratified or
bedded, others foliated or split into millions of thin leaves,
and others subdivided only into masses by occasional
cracks; and these three principal varieties seem to repre-
sent, 1st, those which were deposited in water and after-
wards crystallized; 2d, those which were ejected from vol-
canoes as dust or ashes and afterwards crystallized; and 3d,
those which flowed up from the interior of the earth as
lava and crystallized on cooling. But there'is such variety
in each kind, and so much discussion among microscopical
56 GEOLOGICAL SURVEY OF PENNSYLVANIA.
geologists over these different varieties, as to leave the
whole subject still in doubt and confusion.
Fifthly, that they may all be broadly grouped under two
heads in respect of their chemical constitution. For the
crust of the earth is almost entirely made out of three ele-
ments, two metals and one gas ; the two metals being sil-
icon and aluminium, and the gas being oxygen. The
other elements known to chemists play subordinate parts.
First, the union of oxygen with silicon makes silica
(quartz, rock crystal, opal, <&<?.); and the union of oxygen
with aluminium makes alumina (corundum.} Then, the
union of silica and alumina makes glass (fe spar, porcelain
clay, &c.). Therefore, the ball of the earth may be said
to have a glass coat or crust, which may be likened to the
slag of an iron furnace; not pure transparent glass, but
glass mixed with earths and metals of various kinds in
smaller proportions, lime, magnesia, soda, potash, iron,
manganese. Now in the chemical union of silica with al-
umina the silica plays the part of an acid, and the alumina
plays the part of a base, being the fundamental element
or basis of the union. Hence all rocks which have more
alumina than the silica can unite with are called basic
rocks; and thes.e which have too much silica for the amount
of alumina present are called acid rocks. But as silica
unites in the same way with lime, magnesia, soda, potash
and iron, which general accompany alumina, a great
surplus of silica was required in the creation, and was
amply supplied; so that a considerable portion of it
remains by itself in the form of quartz (rock crystal).
This is seen scattered through rock in brilliant transparent
crystals ; especially in granite. The rest of the silica is
united with the alumina in shining waxy crystals (felspar)
of various colors. When these quartz crystals and these
felspar crystals make up the whole of a rock it is called a
syenite. But when iron is present, then the rock shows
millions of glittering spangles, exceedingly thin films of
mica (white or black), and the rock is called a granite.
With other combinations the iron forms black prisms of
hornblende, and the rock is called hor tiblendic granite.
HIGHLAND GNEISS. 57
If the silicate of alumina has separated from the quartz
by slow cooling into great crystals of felspar, the rock is
called a porphyry ; and when a small mixture of iron, &c.
gives the felspar a rose tint, red poryJiyry. From these
few specimens of variation it may be easily seen what
infinite variety of grain and color the Azoic rocks present,
although they are all mere glass.
Sixthly, that the Azoic formations are enormously thick.
But their true thickness has not been accurately measured
in any country; nor can it be measured; because, being the
oldest known rocks, they have suffered more than all from
waving, compressing and overturning movements in the flex-
ible earth crust, both in their own time and in all succeed-
ing ages ; so that at no place in any country can they be
seen lying flat; but always uptilted, at all angles, and so
folded and twisted, so cracked, veined and faulted, as to
defy measurement, and make it often impossible to
decide which is top and which is bottom to them; so that
their order of arrangement is in dispute ; and some experi-
enced geologists declare that we must be satisfied to con-
sider them as a whole, without attempting to subdivide
them into series of formations, with separate dates and
names. This opinion, however, is not shared by most geol-
ogists, and various methods of arranging them are in vogue,
under such names as Laurentian, Norian, Arvonian,
ffuronian, Montalban, DimUian, Pebidian, &c., which
may be found in text-books and other writings of geology,
but which have no real meaning except in the districts
where they were first invented, and not in all cases a cer-
tain meaning even there. For when the supposed or imag-
ined order of the Azoic rocks in one region or country is
applied to another region no one is satisfied with the result,
and some other order must be invented to suit each local
exhibition. If all the Azoic rocks were truly and certainly
stratified, or deposited as successive layers of sand and
mud in water, and afterwards crystallized and folded up,
there would be some chance of learning their disposition,
and getting somewhat near to the real thickness of the
whole. But so many lava and volcanic ash beds lie among
58 GEOLOGICAL SURVEY OF PENNSYLVANIA.
them, and such huge and numerous outbreakings of fluid
rock from the earth's interior through and between them
have happened, and whatever bedding they may once had
is so obscured by foliation arid cleavage planes produced by
pressure, that taking all these things together into consid-
eration the wise geologist will be cautious of forming an
opinion where Nature seems resolved to leave us in the
dark. This much alone is evident, that the Azoic rocks are
thick enough to make whole mountain ranges. In New
Hampshire and Vermont they are imagined to be 77,000
feet thick.* In the Lake Superior region where six sub-
divisions of them have been devised, the upper five are
thought to measure more than 18, 000 feet, f In Pennsylva-
nia, where the Schuylkill cuts through a part of them for
twenty miles from Conshohocken to Philadelphia, they seem
to measure at least 15,000 feet, with an unknown additional
quantity beneath the valley of the Delaware river.
Lastly, that all the great magnetic, specular and titani-
ferous iron ore beds, beds of plumbago, beds of crystalline
phosphate of lime, and beds of red jasper are of azoic age,
but not in the oldest series of its rocks. To the same age
belong the tin ores of Cornwall, New Hampshire and Da-
kota, the corundum and beryl beds of North Carolina, the
mother rocks of the Brazilian diamonds, and the turquoise
rocks of Mt. Sinai. The serpentine beds of the great lakes
are of that age; probably those of the Alps and Appenines;
perhaps those of southeastern Pennsylvania and Mary-
land; but those of Northampton county in our state, and
others elsewhere may be of later age4 The so-called Eozoon
serpentine-limestone beds of Canada, Massachusetts and
Bohemia are in azoic districts; and many groups of crsytal-
line limestone strata of great thickness were deposited
*Desc. of Geol. Sect, crossing N. H. and V., by Prof. C. H. Hitchcock,
Concord, N. H., 1884, p. 33.
fN. H. Winchell, in Amer. Naturalist, Oct., 1884. R. D. Irving in
Presidential address to Wise. Acad. Sci., Dec. 30, 1884; and Art. 33, Amer-
J. of S., March, 1885.
JGeol. Hist., Serpentiees, T. S. Hunt. Trans. R. S. Canada, Vol. I, Sec.
IV, Montreal, 1883. But see T. D. Rand, Proc. Acad, N. S. Phila., March,
1890, page 95.
HIGHLAND GNEISS. 59
before the appearance of life upon the planet, unless the-
theory of their organic origin be adopted, or the old
exploded theory of their igneous origin be so dressed up
as to be again presentable.
From what has been said above it will appear that our
knowledge of the earliest chapter of geological history rep-
resented by the Azoic or No-life rocks amounts onj.y to
a confused perception of great events taking place at the
consolidating surface of the globe through a great length
of time, without being able to tell with any certainty what
those events exactly were, or how they were brought about.
Fire and water were cooperating in the slow preparation
of continents and oceans capable of sustaining every form
of life which should afterwards appear. The atmosphere
was gradually clearing itself. The sun went on contracting
its dimensions. Of the moon we know nothing; it may
have grown cold and lifeless long before, or not until after-
wards.
But when this picture of apparent vast obscurity and
confusion is carefully studied, as it has been for many
years, and more closely now than ever, by a host of shrewd
geologists, provided with three kinds of apparatus for in-
vestigation, the pickaxe, the microscope and the retort, in-
numerable items of positive knowledge come to view, and
the geology of the Azoic rocks takes practical shape and
may be relied on as a useful guide in the affairs of human
business.
Some steps even have been taken towards the solution of
theoretical questions of age and order of arrangement.
Thus rocks supposed to be sedimentary have been shown
by a study of their microscopic crystals to be volcanic
ashes, * or by their banded structure to be lava flows, f
or by the shape and connection of their atoms to be crys-
talline masses crushed into the form of laminated schists. :{:
On the other hand, iron ore deposits once assuredly
*The felsites and their associated rocks north of Boston. J. S. Diller,
Bull. Mus. C. Z., Harvard College, Cambridge, 1881, Vol. VII, p. 168.
fThe Azoic system, J. D. Whitney and M. B. Wadsworth, Bull. Mus-
C. Z., Vol. VII, 1884.
f Prof. Bonney 's papers on the rocks of the Alps.
60 GEOLOGICAL SURVEY OF PENNSYLVANIA.
taken to be volcanic, have been found by mining operations
to be true sedimentary beds, deposited in water, 'and prob-
ably in a manner similar to the beds of magnetic iron sand
now forming on the northern shore of the Gulf of St. Law-
rence and along the coast of California.
The study of the Azoic rocks in many countries has been
conducting geologists gradually to the conclusion that,
however difficult it may be to classify them in regular order
of time or superposition, yet that as a whole they separate
themselves naturally and broadly into a lower, older, more
massive, darker Tiornblendlc series, and an upper, younger,
more thinly-bedded, lighter-colored micacious series, con-
taining the most ancient iron ore, serpentine and marble
beds. The older series, if such it be^is known in Europe as
the Fundamental gneiss, and in America as the Laurentian
system. The upper series is often called the Newer gneiss
by those who feel unwilling or unable to subscribe to any
universal Huronian theory, or who suspect that the whole
or parts of it may possibly turn out to be more recent sed-
iments disguised by recrystallization, an idea once popular,
then falling into disfavor, and now struggling to regain its
reputation against vehement and powerful protestations.
But just here the Story of the Creation halts to ask itself
three questions : 1st, Whether there could have been any
serious interruption of events between the Older and the
Newer Gneiss ; 2d, Whether there could have been a gen-
erar deposit of the same kind of Newer Gneiss upon the
surface of the earth to such an extent as to make it now
recognizable in places so far apart as the opposite shores of
America, or the opposite sides of the Atlantic; and, 3d,
Whether, if life had then commenced upon the planet, all
traces of it could have been completely lost, the closest ex-
amination failing to detect them. Until these three prime
questions are answered a satisfactory history of the Azoic
age or ages can by no means be written ; nor can Azoic
geology be other than an unconnected description, an
unclassified catalogue of the rocks (with their included min-
erals) which occupy isolated areas of the earth's surface,
projecting through the sediments of later times.
HIGHLAND GNEISS. , 61
The terms Laurent ian and Huronian are local and
peculiar to the Canada survey. The range of mountainous
country which extends from Labrador westward across the
Snganay and Ottawa rivers, north of the river St. Lawrence,
and Lake Superior, is made up chiefly of massive reddish
and grayish hornblendic granite and gneiss rocks, and with
great beds of crystalline limestone in the upper part of the
series, the whole being called the Laurentian System.
To the south of this mountain land, along the north
shore of Lake Huron and extending westward through the
Marquette iron region into Wisconsin, appear, finely ex-
posed to view, beds of vitreous quartzite, red and white,
beds of conglomerate, holding pebbles of jasper, chert and
limestone, beds of chloride slate, beds of reddish limestone,
beds of lava of various kinds and volcanic glass, beds of sul-
phuret of copper ore, and, in the western part, vast beds of
jasper and specular iron ore, the whole being called the
Huronian System.
The Laurentian system is directly connected by the
Thousand Island rocks with the great Adirondack mountains
of northern New York. The Adirondack rocks are the same
as those of the Laurentian mountain belt of Canada ; but
no Huronian rocks appear on or around them ; unless the
Green mountains of Vermont are Huronian.
No one doubts that the Adirondack rocks when they sink
at Lake George rise again a hundred miles further south
as the Highland rocks of the Hudson river above and below
West Point. The Hudson Highlands range northeast a
few miles and then sink out of sight beneath sedimentary
formations. But in the other direction, southwest, they
range away across New Jersey in an unbroken belt of
mountain ridges called the Highlands of New Jersey ;
cross the Delaware river into Pennsylvania between Durham
and Easton ; cross the Schuylkill river above and below
Reading and then sink underground.
In Pennsylvania the New Jersey Highlands are called
the Durham and Reading hills ; or the Lehigh hills ; or
the South mountains of Northampton and Lehigh counties;
or the Highlands of Pennsylvania. This last name is the
62 GEOLOGICAL SURVEY OF PENNSYLVANIA.
most convenient. There seems no probable objection to be
urged against recognizing in the rocks of the Highlands of
New York, New Jersey and Pennsylvania, the rocks of the
Adirondack region and of the Laurentian mountains of
Canada. Therefore the term Laurentian gneiss has been
freely used in the Reports of Progress of the Survey to
signify the rocks of the Pennsylvania Highlands.
But it is quite otherwise with the Huronian rocks of
Canada. These are nowhere recognized along the High-
land belt from the Hudson to the Schuylkill.
We will see hereafter whether they appear in other parts
of Pennsylvania, in the South mountains of Cumberland
and York, Favette and Adams counties.
THE ARCHAEAN HIGHLAND BELT. 63
CHAPTER VIII.
The Archcean Highland belt of Pennsylvania and New
Jersey.
In New Jersey the highlands of older or archsean gneisses
have been surveyed with instruments, and mapped in con-
tour lines, to bring to view all the features of the surface.
Some important facts of geology have been thus revealed.
These are given in Prof. Cook's annual report of 1884,
pages 61 to 68, in a clear and careful manner; and they are
of equal value for understanding the geology of the same
Archsean Highland belt in eastern Pennsylvania. They
may be briefly stated thus :
1. The Highlands of New Jersey is a belt of country
made up of parallel mountains crossing the state in a N. E.
and S. W. direction, with heights varying between 1,000
and 2,000 feet above tide.
2. Each mountain is composed of a series of smaller
oblique crest-ridges; and the stratification does not follow
the general course of the mountain as a whole, but of these
oblique crest-ridges. Thus, the strike of the beds and of
the crest-ridges of the Ramapo mountain is not N. 38 E.
which is the course of the southeast foot of the mountain,
but N, 20 E.
3. The same strike is not maintained across the state;
for near the New York line it is more N. E. and S. W.; in
the middle district more nearly N. N. E. and S. S. W.; and
towards Pennsylvania more N. E. and S. W. again.
4. Therefore, while the mountains have been elevated as
a parallel series of large arches, they have been subse-
quently pressed into a much more numerous series of
smaller rock-folds by a side pressure which has acted
obliquely.
64 GEOLOGICAL SURVEY OF PENNSYLVANIA.
5. The folds are manifested in some places by opposite
southeast and northwest dips; rarely less than 45, in most
cases exceeding 60, and often vertical. Dips towards the
northwest are not uncommon; but nevertheless, the prevail-
ing dip is toward the southeast; therefore, it is to be sup-
posed that a large number of the steeper southeast dips
are exhibited by strata which have been pushed northwest-
ward beyond the vertical so as to lie now with their under-
sides uppermost.
6. As this structure characterises the belt of the high-
lands of northern New Jersey as a whole, it seems impos-
sible to doubt that the azoic gneiss formations are made
up of regular beds of sediment, deposited one over the other
in some ancient sea, and afterwards crystallized. It is
hard to imagine them in any sense volcanic rocks. For
all we know of volcanic rocks leads us to believe that irreg-
ularity is their chief feature. Even when, like the lava
beds of the far west, they spread abroad over thousands of
square miles, they construct nothing resembling the geology
of these highlands.
7. But the regular crest-ridge structure of the highlands
is not shown in all parts of the map, nor is^the appearance
of stratification universal. Dykes and veins of unstratified
rock are common in all parts of the highlands. There are
also masses of syenite or hornblendic granite of great size,
which also may or may not be of the nature of the lava
coming up through fissures. One such belt is two miles
wide; another has a diameter of three miles, the only sign
of bedding noticeable being the parallelism of its minerals
in some specimens, and the rock being an almost exclusive
mixture of white feldspar and glassy quartz. Wherever
the map does not show the regular oblique crest-ridge
structure (that is, where the mountain tops are shaped by
erosion in various directions) there such unstratified masses
may be justly viewed as breaking the stratified system.
8. No contacts of the stratified and unstratified syenite
or granite have yet been noticed, and, therefore, their rela-
tions to each other are a matter of conjecture. The un-
stratified masses are of irregular shape and seem to have
THE ARCHJ3AN HIGHLAND BELT. 65
nothing to do with the northeast and southwest belting of
the stratified gneisses.
9. The stratified rocks of the highlands cannot as yet be
grouped in any definite order of superposition; and the
same varieties of kind are to be found in all parallel ranges
or belts. A representative collection of rock specimens
from one belt might pass for that from the next, or any
other; and collections made along many lines across the
region resemble each other. The varieties of rock in any
given area are endless; but on looking over the entire collec-
tion from all parts of the highlands, two principal varieties
are recognized as predominating.
10. One of these, a light-colored or gray variety, is com-
posed chiefly of white or pinkish-white potash -feldspar
(orthoclase) and glassy quartz, but containing usually small
brown-black scales of mica. Thisfeldspathic gneiss often
contains magnetic iron, hornblende, phosphate of lirrie and
sulphide of iron, and perhaps lime-soda feldspar.
11. The other, a greenish-black variety, is made up chiefly
of hornblende, with dark mica; but when the mica becomes
more abundant than the hornblende the rock turns into a
dark mica-schist or micaceous gneiss. The feldspar is
white and sometimes triclinic. Some quartz is usually
present.
12. Chemical analyses show that the feldspathic gneiss
is largely siliceous, with a comparatively small percentage
of alumina, scarcely any iron oxide, still less lime and
magnesia, and no excess of potash and soda; and that the
Jiornblendic gneiss is deficient in silica, potash and soda,
but has the more iron, lime and magnesia. But recent de-
posits show the same elements in similarly varied mixtures.
The azoic rocks of the highlands therefore may have had
a sedimentary origin, although they are so highly crystal-
line; and if so, their original stratification ought to be more
or less recognizable in spite of changes wrought by heat
and pressure.
66 GEOLOGICAL SURVEY OF PENNSYLVANIA.
The Pennsylvania Highlands.
Such is the lesson taught by the survey of the New
Jersey highlands; and it is repeated by the survey of the
same belt in % its extension in Pennsylvania. All that has
been said by Prof. Cook of the New Jersey azoic rocks, is
confirmed by Mr. D'Invilliers in his report on the azoic
rocks of Berks county, described in his Report of Progress
D3, Vol. IT, 1883, pages 49 to 57.
These Pennsylvania highlands also have been instru-
mentally surveyed and mapped in contour curves on a large
scale (1,600 feet to one inch) and published (on 16 sheets),
in an atlas to accompany Reports D2, D3 ; with a geologi-
cally-colored index map (on one sheet), on a reduced scale
(2 miles to an inch) showing : the ridges of gneiss, both
parallel and irregular ; the patches of sedimentary sand-
stone which once spread in a continuous sheet over the
whole of them ; the limestone valleys north and south of
them ; and the isolated limestone vales between them,
proving that the limestone formation also once spread con-
tinuously over the whole region. Of these facts more will
be said hereafter in narrating the history of the sedimentary
formations. At present we are only concerned with the
Azoic mountain ridges themselves, and the nature of the
crystalline rocks of which they are composed, concerning
which the following statements may be confidently made :
1. The Pennsylvania highlands make an Azoic belt, of
irregular width, in a W. S. W. direction from the Dela-
ware to the Schuylkill, south of the Lehigh river. But iso-
lated, short, small ridges rise through the overlying sand-
stone and limestone strata north of the Lehigh river, show-
ing that the Azoic floor extends underground under middle
and northern Pennsylvania, as it does under New York.
2. The sheet maps plainly exhibit an oblique arrange-
ment of N. E. and S. W. bearing subordinate ridges ; and
the limestone vales of the belt conform rather to this direc-
tion than to that of the belt as a whole. This oblique ten-
dency, however, seems to belong to the more ancient fold-
ing of the Azoic rocks rather than to the later movements
THE ARCH.EATST HIGHLAND BELT. 67
which folded the overlying sedimentary strata. This is just
contrary to what would be expected by a classical geologist.
Nor has it all the force that it would have were the appar-
ent stratification of the gneiss not brought into doubt by
the abundance of cleavage planes, and were the apparent
stratification of the gneiss traceable for long distances in
any one fixed direction. But the very reverse of this is
true.
3. The apparent stratification of the gneiss rocks varies in
dip and strike incessantly, as shown by the arrows on the
map sheets and by the detailed description of outcrops in
the report, pages 57 to 98. From this it will appear that
the rocks dip to all points of the compass, and commonly at
high angles, rolling over from south to north and from east
to west sometimes in well-defined arches, which often end
or die down suddenly. Some of these arches run length-
wise of the belt ; others are oblique to it and pass beneath
the overlying sandstone. Thus, near Maple Grove the arch
of the Gap Hill is marked by a N. 34 W. dip (of 87) and
a S. 60 E dip (of 60), but at its east end are dips of S. 51
E. (52), S. 48 E. (45) and N. 70 W. (47), and here the
arch lies under the sandstone. Some distance from this the
gneiss dips S. 70 E. (50), and further on, S. 75 E. (57),
and S. 80 E. (80). Along this ridge there is plainly a local
general strike very oblique to the general direction of the
whole Azoic belt.* On the other hand, groups of expos-
ures show a general strike east by north, or E. N. E., coin-
ciding with the belt.
4. On account of this excessive irregularity which per-
vades the whole Azoic belt it has been found impossible to
classify its rocks into a series of formations, or even to
show with any satisfaction the course of the outcrops on the
map. All that can be said about them is that they are a
badly crumpled-up mass of strata, of unknown thickness,
all more or less thoroughly crystallized, of every grade of
thick and thin-beddedness, of every tint of gray from nearly
white to nearly black, of nearly every possible mixture of
quartz, feldspar, hornblende, magnetite and mica, some of
*Report D3, Vol. 2, p. 63.
68 GEOLOGICAL SURVEY OF PENNSYLVANIA.
them being a syenite, some a granite, some a granulite,
some a hornblende-schist, some a mica-schist, some a mag-
netic iron ore ; and all these kinds passing into one another,
and overlying one another, as if the original sediments (if
sediments they were) were of the most mixed and varied
character, yet all derived from essentially one source and
belonging to one age, an age moreover not overrich in
lime and magnesia, if we may judge of it by the absence of
crystalline limestone beds and beds of talc or serpentine.
5. The same broad distinction between a prevalence of
dark hornblendic gneiss (syenite} carrying beds of magnetic
iron ore and destitute of quartz, and a prevalence of light-
colored, thick-bedded granular quartz-feldspar gneiss
(granulite\ destitute of mica, is noticeable all through the
l>elt of highlands.
6. The Tiornblendic rock is full of grains of magnetic
oxide of iron; and a good deal of what appears on first
glance to be hornblende is in reality magnetic oxide of
iron. The quantity of iron held by these strata must be
immense; and, therefore, it excites no wonder to see many
of the beds rich enough in iron to be mined as beds of mag-
netic iron ore. Where all this disseminated iron came
from is a mystery; but is no greater mystery than where
the grains of quartz sand came from which make up so
large a part of the granulite variety. Both these constitu-
ent elements of azoic strata furnish very strong evidence in
favor of their sedimentary origin. But if this be granted it
still remains an unanswered question where were the more
ancient land areas from which these quartz and iron sands
were washed down into the azoic sea ; and what kind of
country could that have been to furnish such stupendous
quantities of iron ?
7. The granulite strata consist of grains of quartz,
mixed with pinkish- white feldspar, and also with some
grains of magnetic oxide of iron. The amount of quartz,
however, is seldom in excess of the feldspar; that is, the
quartz usually occurs in small glassy grains, and not in
chunks. The rock is therefore, usually, as fine-grained as
it is massive, and in this respect reminds one of the massive
THE ARCHAEAN HIGHLAND BELT. 69
sandstone strata of later ages and undeniable sedimentary
origin. The feldspar varies in color between dull white
and flesh-pink, greenish and bluish tints being rarety seen.
The feldspar also varies in its relative percentages of
potash, lime and soda. The strata in which the potash
feldspar abounds are hard, resist the weather and show
their stratification plainly; but those in which the soda
feldspar, the soda-lime feldspar and the lime feldspar
abound are softer, weather into rounded bowlders, and get
so covered with the soil which they make in mouldering as
to conceal their stratification, and this give a soft and
rounded aspect to the hill slopes.
8. On the whole, the ridges which are made chiefly by
the hornblende gneiss are higher and rougher, and their
crests are rocky; but the ridges which are made chiefly by
fjranulite rocks have rounded summits. The ridges on the
northern side of the belt, where the iron mines are, show
the hornblende character of topography more plainly than
the southern side of the belt; and this geographical fact
may have an important geological significance. The soils
also indicate the difference; for the hornblende districts are
covered with earth stained by the decomposition of the iron
element to a deep brownish red; whereas, the granulite
districts are covered with light-colored, sparkling, sandy
earth.
9. That the iron ore beds are original parts of the strati-
fication and not ejections from below is- plainly shown in
these highlands ; for they lie in lens-shaped plates between
the gneiss rocks; fining off to an edge all round; or rather
fading away into gneiss rocks so gradually that one cannot
say where the bed ceases to be an ore and becomes an un-
profitable rock.* It seems conclusive logic that if the
magnetic ore beds lie thus between the gneiss rocks, the
whole azoic mass must be a sedimentary formation.
10. The absence of any noteworthy mica schist forma-
*Report D3, Vol. II, page 239. Along the southern edge of the azoic belt
some limestone has been deposited with the magnetic ore ; and there is a.
hand specimen in the Pennsylvania collection, which shows three parallel
layers of ore averaging an inch in thickness, separated by two layers ot"
Hmestone each three or four inches in thickness.
70 GEOLOGICAL SURVEY OF PENNSYLVANIA.
mation,* of any remarkable crystalline limestone beds,f and
especially of any magnesian formation (chlorite, talc, ser-
pentine,:}: &c.), in the Pennsylvania highlands between the
Schuylkill and Delaware rivers, shut in as they are on
both the north and south sides by sedimentary fossiliferous
sandstone and limestone formation, patches of which lie
upon the very summits or are preserved between the ridges,
makes it useless for us to seek for a Huronian formation
here. To imagine that it once existed, but has been swept
away, or that it lies buried many thousands of feet deep to
the north and south of the highland belt, is a mere conjec-
ture, worthless because unsupported by any known facts.
The Archaean rocks of the highlands of New Jersey pass
across the Delaware river into Northampton county, Pa.
and extend in parallel ridges through southern Lehigh and
Berks as far as the Schuylkill river at Reading, where they
sink (westward) beneath the Great Valley limestone, not to
rise to the surface again (as a mountain range) short of
York and Adams counties.
The South mountains of York and Cumberland, Adams
and Fayette were formerly supposed to be a geological con-
tinuation (or revival, geographically, going southwest) of
the highlands of New Jersey and the Easton- Reading, or
Durham hills ; but it is nearly certain that the South
mountains are for the most part composed not of Archrean
(Laurentian) but Cambrian (Huronian?) strata.
*Both muscovite and biotite mica has been found in fine scales and in
large plates in several places. See D3, Vol. II, page 53.
fThe crystalline limestone bed in the report of the first survey, as running
through Colebrookdale, was sought for carefully but not found by the
second survey. D3, Vol. II, page 56.
JGreenish talcose slates appear along the southern edge of the belt at one
or two places and will be described in another place.
A narrow outcrop crosses the Schuylkill below Reading and runs a mile
or two west. A lew miles further west they appear again in Mulbaugh hill-
But with these exceptions there is a gap of about sixty miles in the direct
Highland-Blue Ridge range which may be said to extend from Massachu-
setts to Georgia. But in northern Chester, south of the direct line, they oc-
cupy the surface in the Welsh mountain region, and still further south
there is a Philadelphia-Baltimore belt of them to be described further on.
THE ARCHAEAN HIGHLAND BELT. 71
Archxan types in New Jersey.
The Archaean (Laurentian) rocks of Pennsylvania have
been studied as closely, but in some respects under less
favorable circumstances than those of New Jersey, where
they have been subjected to repeated examinations and are
exposed in a bolder manner and in connection with mining
operations at many places. The New JerSey report of 1889
is of special value.
It distinguishes four types or characteristic masses of
highland strata, without positively affirming what their re-
spective ages are, how they underlie or overlie each other,
or what their mutual geological relationships may really be,
but very particularly describing their geographical ranges
and their mineral constituents.*
I. The Mount Hope type (FeldspatMc gneiss of Smock;
in part the Hornblendic gneiss of Britton) is a nuartz-feld-
spar-magnetite rock, varying from massive to coarse and to
fine-grained and beautifully foliated, often obscurely foli-
ated on a fresh unweathered surface ; the quartz generally
in shot-like grains pressed into the cleavage face of the
feldspar, which, under the pocket lens, gives a character-
istic unmistakable spotted (poicilitic) appearance to a
broken specimen ; the feldspar both orthoclase and plag-
ioclase ; the magnetite usually in rough, irregular little
grains, occasionally in octrohedral crystals, and sometimes
largely replaced by hornblende and scattering flakes of
black mica (biotite}. These massively-bedded and usually
well-foliated strata have numerous interstratified layers of
hornblende-feldspar rock without quartz, some of them only
a few inches thick, others many feet thick, and usually
quite destitute of magnetite. The typical Mount Hope
rocks usually occupy the highest ground or summits of the
ridges flanked by the Second or Oxford type of rocks;
which would make them older than or underlying the Ox-
ford ; but there are important exceptions to this general
*New Jersey An. Rt 1889, part 2, page 12, Geological Studies of the
Archaean Rocks, by Frank L. Nason. See Geol. Rts. of Pa., by Persifor
Frazer, Fred. Prime, C. E. Hall and.E. V. d'lnvilliers, C, C2, C3, C4, C5,
D, D2, D3, Vol. 1 and 2.
72 GEOLOGICAL SURVEY OF PENNSYLVANIA.
statement which perhaps weaken somewhat the correctness
of that conclusion.
The Mount Hope type rocks may be separated into three
classes: 1, Light-colored quartz and feldspar rock. 2, The
same, darkened with magnetite. 3, The same, darkened
with hornblende, or biotite, or both. Texture and general
appearance the same in all. Dark (non-eruptive diorite-
looking) feldspar-hornblende layers are often interstratilied
with them, and beds of solid iron ore occur in all three.
II. The Oxford type (Syenite gneiss of Smock; in part
Honiblendic gneiss of Britton), always well foliated (even
in fresh broke specimens) and not so heavy-bedded as the
Mount Hope type, consists of feldspar (both kinds) and
hornblende, with grains of quartz frequently rounded and
imbedded in the feldspar; always only a small proportion
of magnetite (sometimes octohedral) ; the hornblende
usually distributed in strings so as to give the rock a
striped appearance; and the longer axes of feldspar often
oblique to foliation. The railroad tunnel at Oxford tunnel
shows all the various phases of this type; but no contact
with the other type can be seen; the change however
seems abrupt and radical. The Oxford rocks are, however,
almost everywhere seen on the flanks of those ridges the
central mass of which is of the Mount Hope type. The
Mount Scott range which reaches the Delaware is a suffi-
cient example and introduces the distinction of types into
Pennsylvania.
III. The Franklin type (probably the Biotite gneiss of
Smock and Britton); foliation less distinct; texture more
uneven ; crystals of biotite, &c. at angles to each otlier ;
eyes of quartz and feldspar singly or mixed frequent
(augenstructuf); rocks rather thin bedded; frequent inter-
strata of biotite and hornblende schist; essentially a quartz-
orthoclase -biotite rock (plagioclase rare); quartz and feld-
spar grains usually sharply angular, in striking contrast
with other types.
IV. The Montmlle limestone type; not certainly known
to belong to the Archaean; possibly of later age. Southeast
belt (A); bluish gray, rarely white; crystalline ; holding
THE ARCHAEAN HIGHLAND BELT. 73
great quantities of serpentine, more or less chrysolite; also
diopside, in some places small crystals of muscomte mica;
never tourmaline, no zinc, no iron. Northwest belt (B)
sparkling white; holding graphite, tremolite, tourmaline,
pyrite, great quantities of zinc, and also beds of iron.
74 GEOLOGICAL SURVEY OF PENNSYLVANIA.
CHAPTER IX.
The ArcJicean rocks of Pennsylvania.
1. In the Reading and Durham Jiills.
Prof. Prime and Mr. C. E. Hall have described the high-
land rocks in Lehigh and Northampton counties in the
same general terms;* but there is mention made not only
of hornblendic and feldspathic gneisses, but occasionally of
mica-schists, rocks composed of white mica and decom-
posed white feldspar. f Mr. Hall says, that the crystalline
rocks are composed chiefly of quartz and feldspar; that mag-
netite is disseminated throughout the rock in all parts of
the region, and that the magnetic iron beds are distinctly
interstratified; that in some places the rock contains small
amounts of dark mica and pyroxene (hornblende) and that
occasionally particles of mica and magnetite are found to-
gether; but that many rocks are wholly of quartz and feld-
spar. One vein (?) of corundum has been found.J
The Delaware river cuts through five ridges of these
rocks, separated by valleys filled with sedimentary lime-
stone. Some of these ridges seem to be rock arches pressed
over northwards. In the third ridge at least 800 and
perhaps 1,200 feet of strata show themselves.
This anticlinal structure, however, cannot be made out
in the ridges of the belt as a whole. Some of the ridges
seem to be monoclinal and others synclinal. It is quite
impossible to be sure of the correctness of any kind of
structure anywhere. Nevertheless, there are places where
plenty of opposing dips can be observed, although it can
seldom be decided that they lie on two sides of an arch, or
*Reports D, D2, D3, Vol. I.
|D2, page 7.
$D3, Vol. I, pages 254-255.
The difference being due to the possible existence of a roll.
OLD GNEISS IN CHESTER COUNTY. 75
on two sides of a basin. One example will be sufficient to
illustrate the difficulties.
The Hexerikopf ( Witch s head) is the highest point of
land southwest of Easton where two of the azoic ridges
converge. On its north slope gneiss rocks dip to the S.
E. 54; at its south brow 29; on the south slope they dip to
the N. W. 36, 60 and 50. There is certainly a basin on the
south slope, even if there be an overturned arch at the
crest; if there be no such arch then the whole mountain is
a basin with at least 1,200 and possibly 2,000 feet of azoic
strata visible on each of its sides.*
#. In northern Chester county.
The Welsh mountain azoic district of northern Chester
county is nowhere more than 500 feet above present sea
level; is surrounded by sedimentary sandstone and lime-
stone (although the northeastern rim is concealed by still
later deposits); and was once covered by them, as is shown
by the patches of sandstone left upon it. It does not lie
in the W. S. W. prolongation of the highland belt of Berks
county, but to the south of it; the present interval between
their edges being ten miles. This interval represents an
ancient valley, of great but unknown depth, now filled up
with Palaeozoic white sandstone and limestone, covered in
turn by a thick mass of Mesozoic brown sandstone and
shale. The azoic rocks of both districts undoubtedly meet
beneath this valley and form its floor, covered entirely by
the white sandstone and limestone which rise to the pres-
ent surface on both sides of it; the sandstone being about
100, and the limestone about 2,000 feet thick, and perhaps
covered in places by a third deposit of slate; but of this
we know nothing; only, it is certain that the limestone in
the valley suffered erosion before the Trias sand and shale
was deposited upon it in much later times. The thickness
of these later brown sands and shales is also unknown;
but, judging by the dips and distances, they must be nearly
*See the accompany page plate, showing both alternative constructions;
also the description of the locality and its rocks on pages 75 and 251, of
Report D3, Vol. 1, 1883.
76 * GEOLOGICAL SURVEY OF PENNSYLVANIA.
4,000 feet thick along their northern edge. The ancient
buried valley, then, must be about as deep beneath the
present mountain surfaces to the north and south of it as
the valley of the Rhone between the two enclosing ranges
of the Alps. Originally this could not have been the case;
for the brown sandstone strata all dip northward at the rate
of at least 500 feet to the mile; so that if they were de-
posited horizontally, either the Highlands were 5,000 feet
higher than they are now, or the Welsh mountain district
has been elevated 4,000 feet.
The Welsh mountain azoic rocks are, as we might
suppose from their underground connection with the High-
lands, the same dark hornblendic and light gray feldspathic
gneisses which have been described in the foregoing pages.
Being more easily destroyed by the weather than the
white sandstone which was afterwards deposited upon them,
their outcrops lie in shallow vales between ridges of white
sandstone;* but this is owing to the fact that the softer
white feldspathic gneisses, interbedded with the harder dark
hornblendic gneisses, make up the greater part of the form-
ation as it appears at the present surface. By far the most
prevalent variety, is a feldspar-quartz rock (granulite) of a
grayish-white color, holding only a subordinate amount of
mica, and deposited in comparatively massive beds. Some
of the finer-grained kinds can hardly be distinguished from
the white sandstone afterwards deposited upon the azoic
rocks. f Micaceous gneiss strata, however, are also some-
times seen; but nowhere in outcrops of considerable
breadth ; and true mica slate only in thin interstratified
layers.
It is very noteworthy, that in this Welsh mountain azoic
h'eld, as in the Highland belt, the hornblendic rocks prevail
along its northern portions, and the feldspathic rocks along
the middle and southern portions.:}: No reason for this
can, in our present knowledge of the azoic formations, be
given. Eor even if it be true that two grand rock waves and
*Dr. Frazer's Report C4, page 163.
fPages 164-165.
tCM, p. 165.
OLD GNEISS IN CHESTER COUNTY. . 77
several smaller ones traverse the district from east to west,
it cannot be proved that the hornblendic gneisses are lower
in the series than the feldspathic gneisses ; or, that they
are brought up only by the northern arch. Such a suppo-
sition is merely a tempting conjecture.
Plumbago beds have been found in at least three places
in the district. One 3 feet thick lies between gneiss strata
dipping 45 to the S. E.* Another is a gneissoid stratum
12 to 15 feet thick containing about 4 per cent, of dissem-
minated graphite, which is shown to be merely an element in
the rock by the fact that the stratum includes horses of
whitish rock without graphite, f An outcrop, traceable for
a long distance, is that of a curious conglomerate (so- called)
containing graphite ; but, although the rock looks like a
conglomerate, it is more likely to be a decomposed por-
phyritic crystalline rock if judged by the fresh character
of its feldspar, the unworn- angles of its quartz crystals,
and the even distribution of the "graphite through it.J
Although exhibitions of plumbago in these azoic rocks
suggest a relationship to the Canadian azoic rocks, they can
have no time value for settling the order of the series, even
were the relative age of the Canadian plumbago beds estab-
lished ; for the origin of the graphite is wholly unknown.
For, while it is looked upon by some as a proof of fusion,
like the graphite in cast iron, others rely on it as a confir-
mation of the sedimentary character of the rocks which
hold it, as if it represented the consolidated and recrystal-
lized remains of living creatures, the first and lowest kinds
of plants or animals. And, in fact, graphite is found both
in lava and in limestone.
Porphyries occur with the hornblende syenite ; and these
consist of a mixture of large crystals of potash feldspar
and white (sometimes amethyst-colored) quartz, sometimes
enough mica being present to make the rock a coarse por-
phyritic granite. The syenite layers are a dark compound
of hornblende and white feldspar, and weather into round
boulders and clay, and show iron stains.
*C4, p. 222. fc4, p. 251. JC4, p. 254.
Dr. Frazer, C4, p. 215. Dr. Genth's analysis of such syenites exhibits
labradorite and andesite with pyroxene.
78 GEOLOGICAL SURVEY OF PENNSYLVANIA.
The absence of limestone and serpentine beds from the
azoic district of northern Chester is as noteworthy as their
absence from the Highlands of Berks, Lehigh and North-
ampton counties.
The Welsh mountain proper is the westward extension of
the northern part of the district into Lancaster county; a
prong of gneiss, covered partially with sedimentary white
sandstone, sinking beneath the great limestone plain of
Lancaster, and not rising again to the surface, although the
sandstone reappears on the Susquehanna river, above Col-
umbia, and again in the Pigeon hills, on the Adams county
line. (Chiques or Hellam quartzite.)
A southern prong of gneiss, covered with sandstone, and
known as the Gap hills and Mine ridge, extending much
further through Sadsbury and Bart townships, sinks beneath
the limestone, and does not rise again to the present sur-
face. At one point on the Susquehanna river, at the mouth
of Tocquan creek, in the center of a flat arch of great
breadth, the gneisses which have been described in the
Highlands and in the Welsh mountain region,* should make
their appearance ; but they do not neither the horn-
blendic nor feldspathic gneisses but the vast arch is made
up of micaceous gneisses and mica schists, apparently
many thousands of feet in thickness, as will appear here-
after in the course of this history.
West of the Susquehanna river, in Pennsylvania, the
highland rocks nowhere reach the present surface, for the
rocks of the South-Mountain-Blue-Ridge range belong to a
different system, as will be described further on. We will
therefore turn back here and describe them as they ap-
pear along the Philadelphia belt in southern Bucks, Mont-
gomery, in Delaware and in southern Chester counties,
where we will find them supporting the white sandstone
and limestone sedimentary formations, but also in contact
with another great azoic system of an entirely different char-
acter and of as yet unsettled age.
*Prof. Frazer's report on Lancaster county, C3, p. 71, 128. See, also, the
third line of the Susquehanna river section, sheet 3, in the Atlas to C3.
OLD GNEISS OF BUCK RIDGE. 79
3. In Bucks, Montgomery and Delaware counties.
At the Delaware river, opposite to the city of Trenton, a
low range of old azoic gneiss is seen rising from beneath the
mesozoic brown sand and shale formation and running in a
straight course west southwestward thirty miles to the
Schuylkill river above Philadelphia. For the first few
miles it is more or less concealed by the earliest Delaware
river gravels. From the gorge of the Neshaminy to the
gorge of the Pennypack, it makes what is locally known as
the Buck ridge, with a constant width of 2^ miles.* At
Willow Grove, in Montgomery county, it splits the
northern fork soon disappearing beneath the edge of the
mesozoic country to make its underground connections
with the Welsh mountain region of northern Chester its
southern fork keeping on, as a narrow thread, into Dela-
ware county, where it spreads out into three separated
areas, the northern one passing on into southern Chester and
the southern one into the State of Delaware.
Between the two forks commences the range of white sand
stone and overlying limestone, of the Chester county valley,
which runs straight W. S. W. for sixty miles, past Con-
shohocken, Downingtown and Coatesville, into Lancaster
county. The valley is evidently a long and narrow basin,
at least towards its eastern end, where the limestone is seen
lying in a spoon of sandstone, and the sandstone lies in the
spoon-shaped depression which splits the ridge of gneiss.
There can be no mistaking the fact that here the Chiques
sandstone reposes directly upon the old azoic gneiss floor
of Pennsylvania, without the intervention of any other
azoic rocks, just at it rests upon the old azoic gneiss of the
Reading hills. So also,for miles along the North Valley
Hill in Chester county, this " North Valley Hill sandstone "
or quartzite is seen lying directly upon the older azoic gneiss
of the Welsh Monntain country
But it is equally evident that the age of the older gneiss
and the age of the sandstone were separated by some great
interval of time, for the sandstone lies comparatively flat
*See map on page 39 of Report 06, and large sheet mapln C6.
80 GEOLOGICAL SURVEY OF PENNSYLVANIA.
upon the nearly vertically upturned edges of the gneiss.
The sandstone basin is real ; the basin of gneiss is false a
mere valley worn out of a much older surface of uplifted,
compressed and complicated rocks. How many ages were
required for working down the ancient range of gneiss into
hills and hollows before the sand of the sandstone was
drifted into the water around the gneiss spurs is the most
important question to be asked of our geology, and the
most difficult to be fitted with a proper and probable answer.
For during those intermediate ages the rain had been al-
ways falling, and the rivers running to the seas, and the
seas adjusting their deposits. But where were the lands
overhung with clouds and traversed by streams? And
where were the seashores along which the tides were rolling
gravel and spreading out the new formations of sand and
mud ? And where shall we seek for the rocks which rep-
resent those gravels, sands and muds ? And in what con-
dition should we expect to find them, crystalline or uncrys-
talline, fossiliferous or non-fossiliferous ?
The Buck, ridge gneiss (always called syenite in Mr.
Hall's reports C5 and C6) has the character of the prevail-
ing rocks of the Highlands and Welsh mountain district.
The rocks are composed chiefly of quartz, feldspar and
hornblende. The beds are often massive, but usually have
thin bands of black mica or of hornblende. They are
syenites, gneissic granites, or granite gneisses. A. peculiar
bluish quartz is a remarkable feature of the formation.*
Small particles of magnetite are in some places scattered
through the rock ; but nowhere in sufficient abundance to
make a magnetite iron ore bed. Graphite occurs ; and in
one place enough of it in the rock to warrant an attempt at
mining, which however was abandoned. f Crystalline
limestone occurs near Rockville, at Van Artsdalen quarry,
so well-known to mineralogists.:}: A gray and red granite
appears between Somerton and Feasterville.
*Report C6, page 4.
fThe old mine on A. Johnson's farm, near Feasterville, Bucks county.
See 06, page 57.
tC6, page 47. NOTE. After his long survey of the Philadelphia belt Mr.
Hall made a careful re-survey of the Highlands. See D2.
OLD GNEISS OF BUCK RIDGE. 81
Now the rock which lies upon it is usually a fine-grained,
thinly-laminated, whitish sandstone, changed by infiltra-
tion of silica into a quartzite, and full of small scales of
light -colored mica ; but some of the beds are occasionally
coarse enough to be called a fine conglomerate; and east of
Willow grove there are massive beds of conglomerate made
up of rolled pieces of the Buck ridge syenite gneiss and the
blue quartz, overlaid by finer sandstone beds and beds of
sandy slate.* This shows that the old azoic (syenite) land
was not very far off, and was bare of any newer azoic form-
ations, mica-schists, micaceous gneiss, &c.; for not a frag-
ment of any such rocks can be found in the sandy conglo-
merate, f
Furthermore, in places where the sandstone was not de-
posited, and where the limestone strata therefore rest
directly upon the old azoic gneiss (as at the furnace
quarries at West Conshohocken on the Schuylkill) the
limestone beds contain similar fragments of syenite which
shows the neighborhood of an old azoic seashore.;}: But
how far the land extended back from the shore (towards
the present Atlantic ocean), or how high into the air it rose,
must be left to the imagination, unguided except by a
single fact, namely, that in a long subsequent time in the
history of the earth, at the end of the Palaeozoic ages and
the beginning of the Mesozoic ages, the azoic syenite land
was out of water just as it was out of water at the begin-
ning of the Palaeozoic ages when the white sand and lime-
stone were deposited. For, at the southern edge of the Mes-
ozoic brown sand and slate country in Bucks and Mont-
gomery counties the bottom beds not only lie directly
upon the azoic range of Buck ridge, but are conglomerates
largely made up of rolled syenite rock fragments. But
whether this particular belt of azoic land remained exposed
to the air through all those Palaeozoic ages, during which
40,000 feet of strata of all sorts were deposited to the north-
west of it, is a question to be discussed more in detail here-
*Exposed in the N. E. Penn. R. R. cut below Willow Grove. C6, page 45.
fC6, page 5.
JC6, page 36.
6
82 GEOLOGICAL SURVEY OF PENNSYLVANIA.
after. But surely Buck ridge could not have remained
through all those ages exposed to aerial destruction unless
it had been at the outset of them a high mountain range.
On the other hand, it could not have been an Alpine
mountain range facing the Palaeozoic sea through all those
ages without doing more than dropping a little gravel into
the white sand-beds here and there, into the lowest beds of
Palaeozoic limestone, and into the lowest beds of the Meso-
zoic sand and shale. Were it the mountainous northwest
edge of an Atlantic continent it must have been somewhere
or other broken by mighty rivers draining such a con-
tinent. Where are the deposits which such rivers must have
made in all that lapse of ages? We will see in due time.
But surely no such rivers opened their mouths in Bucks or
Montgomery counties; for the sandstone (which is indeed a
vast delta deposit, extending far and wide in the United
States, as we shall see hereafter) is so thin in eastern Penn-
sylvania that it can stand for but a transitory operation at
an early period of the Palaeozoic age ; being immediately
followed by the great oceanic magnesian limestone forma-
tion (at least 2,000 feet thick in the azoic regions, but more
than 6000 feet thick in middle Pennsylvania) representing
a totally different relationship of continental and oceanic
circumstances.
In the face of all these difficulties we might assume that
the Buck ridge azoic district was a long narrow island
at the time when the sandstone was deposited around it.
But if so, this island must have been the crest of a moun-
tain ridge belonging to a much larger extent of azoic land
which had sunk and become submerged at least 50 miles
broad namely, from Trenton up the river Delaware to the
gap in Chestnut ridge above Easton; for over the whole of
this breadth, as we have seen, the sandstone and limestone
were deposited. And it looks as if the Buck ridge was
the only azoic island at that time. For the sandstone
patches on the Welsh mountain region and on the tops of
the Berks county highlands remain in evidence that these
were all submerged. Yet this seems a very strange fact on
noticing that the Highland summits now stand 1,000 feet
OLD GNEISS OF BUCK RIDGE. 83
above tlie present sea level, and Buck ridge only about 400
feet.
We should be obliged then to suppose one of three
things, either that Buck ridge has sunk additionally since
then; or that the Highlands have been lifted additionally
since then; or that the whole azoic underground country on
which they both stand has been tilted or warped to produce
the difference of height.
How idle are all such conjectures to account for the im-
aginary fact that Buck ridge remained an island, while the
higher Highlands were beneath the sea level, when the only
reason for supposing it an island is furnished by syenite
pebbles in the sandstone and limestone beds, which- pebbles
may have come from some more distant azoic land no longer
to be seen ?
The impotence of the structural geologist to encounter
such a problem with success becomes more and more ap-
parent as new facts present themselves to be adjusted into
place. Since those remote days in the history of the
planet movements of many kinds, in shape, direction and
degree, have followed each other at shorter or longer inter-
vals, disguising and distorting or obliterating each others'
traces; while the perpetual shifting of the ocean level up
and down in all ages, often produced 'by foreign catas-
trophes, and originating even on the opposite side of the
globe, takes from us the only index and measure of move-
ment which might otherwise be at our command.
We know not when the excessive plication of the Buck
ridge gneisses took place, whether wholly before or partly
after the deposit of the sandstone. As we see them now,
the old azoic strata stand nearly vertical. But it looks as if
two principal folds, both tightly compressed, run along the
ridge, one producing the short north spur at Willow Grove,
the other following the narrow belt or thread, scarcely a
tnile wide, past Chestnut Hill to the Schuylkill just below
Conshohocken. Whether or not these -are true rock arches
is much more than doubtful. But if they be, it is plain to
see that two such arches in a breadth of two miles, if re-
stored by ideal projection upward, compels us to believe
84 GEOLOGICAL SURVEY OF PENNSYLVANIA.
that Buck ridge was once a mountain 10,000 feet high ;
and that it has been torn and worn and washed away down
to its present lowness. There is no difficulty in believing
the fact of its great height, seeing that we have absolute
proof of the former existence of mountains 20,000 feet high
in middle Pennsylvania, where now in the place of them
spread smiling limestone valleys not 800 feet above the
level of the sea. The difficulty lies in finding reasons for
deciding whether the elevation of this mountain range took
place before or after the deposit of the sandstone and lime-
stone of the Chester county valley. For, in the first case,
they should lie more horizontally around it and be mixed
with itsdebris to a vastly greater extent than they are : and
in the second case, they must have covered the mountain,
been pushed up to an almost vertical posture, been eroded
away along with it, and their eroded outcrops be found
now on both sides of it .
To test the question let us look at their present attitude.
On the north side of the Buck ridge proper from Trenton
to Willow Grove, and on the north side of the short north-
ern prong west of Willow Grove, the sandstone and lime-
stone cannot be found; their edges lie concealed under-
ground beneath the Mesozoic brown sands and shales.
But that they are there we know by an accident. Among
the many probable faults in the mesozoic, one is so great in
its vertical displacement the one that runs from the Del-
aware river at Centre bridge (15 miles above Trenton)
south westward to Forestville near Doylestown as to bring
the ground-floor of sandstone and limestone up through the
mesozoic to the present surface. This happy accident,
taken in connection with their appearance again, 15 miles
further north, alone: the south flank of -the Highlands is
quite sufficient to justify us in asserting that they extend
beneath the mesozoic the whole distance (30 miles) between
Buck ridge and the Highlands ; ofcourse everywhere lying
upon the azoic ground floor ; but whether flat and undis-
turbed, or compressed into folds, or simply shifted by
faults, we cannot tell.
From Willow Grove westward to the Schuylkill, along
OLD GNEISS OF BUCK KIDGE. 85
the northern side of the south prong of the Buck ridge,
there is a continuous outcrop of sandstone and limestone
(as has been already said) turned up at various steep angles
from 60 to 90.* These are the north dips on the southern
side of the Chester county valley basin east of the Schtiyl-
kill ; and if the curves of the basin be properly drawn they
show that the bottom sandstone beds must descend to
depths of many thousand feet beneath the present sur-
face. But if the argument from structure be good for
depth, it is equally good for height ; and we are compelled
to believe that these beds once ascended into the air with
these steep dips to an unknown elevation above the present
surface. What is the limit of this their uprise into the air ?
What is to prevent us from believing that they ascended
upon the northern flank of the azoic mountain to its top,
and descended its southern flank to an equal depth beneath
the present surface? In fact, if they can be found along
the southern edge of the azoic ridge, and in a nearly vertical
posture (descending southward beneath the present surface)
must not this be accepted as proof that they arched entirely
over the azoic mountain when it was at its highest ? No,
not quite ; for it will still remain a possibility that the azoic
arch in rising and pushing up a still higher arch of over-
lying sandstone and limestone, broke the upper arch and
left two edges separately projecting (at any supposable
height) between which its own arch (broken or unbroken)
rose still higher naked in the sky.f
But the main point is. are such outcrops of sandstone
and limestone to be found on the south side of the azoic
ridge ? And, if found, can we be sure that they are the
very sandstone and limestone of the north side ? Does the
sandstone lie upon or next to the azoic, and the limestone
upon or outside of the sandstone? In answering these
questions the following statements can be made :
*As shown in Mr. Hall's cross sections, Figs. 18, 19, 20, 21 and 22, on page
43 of Report C6.
fin discussing the Mesozoic belt of Bucks and Montgomery counties, the
elevation of the Asoic mountains of the Philadelphia belt will be offered as
explanation of the northward dip of the 22,000 feet of Mesozoic sediments.
It is evident that the Buck Ridge syenite was once 22,000 feet or more be-
neath its present position.
86 GEOLOGICAL SURVEY OF PENNSYLVANIA.
1. There is no sandstone, no limestone to be found in the
Atlantic coast country southeast of the Buck ridge gneiss
except just at its southern edge. The country between it
and the Delaware river is occupied by a great series of azoic-
rocks, (which will come under discussion in due time)
among which not a single stratum of sandstone or lime-
stone can be found. And beyond the Delaware river the
whole breadth of New Jersey is made of quite recent for-
mations, lying upon a mesozoic floor. If Palaeozoic sand-
stones and limestones exist beneath the mesozoic floor we
must be content to remain ignorant of the fact for many
years at least until the legislature of New Jersey shall
order borings profound enough to reach them to be made,
and for such purety scientific knowledge only.
2. An outcrop of steep sandstone beds actually does
run along the south side of Buck ridge, in an unbroken line
from the Trenton city bridge, 16 miles, to Huntingdon valley
(the Pennypack creek) in Montgomery county. For the
next 6 miles, as far as Abington station on the N. Penn. R.
R. it makes no show. Then (at Waverly Heights) it re-
appears and runs for 3 miles to near Chestnut Hill, beyond
which it is no more seen.* It forms a low ridge, , and is
known as the Edge Hill sandstone (eurUe, quartzite, ita-
columite) ; many yards in thickness ;f standing vertical;
with the surface edges of the beds often pressed, crushed
or "creeped" over at an angle always towards the south,
(as seen in fig. 17, 06, page 41) ; so that the surface ex-
posure has given the false impression that the formation
dipped northward under the azoic ridge ; but it is the same
formation as the sandstone on the north side of the ridge.
3. An outcrop of vertical beds of limestone also runs for
some distance along the south side of the sandstone east of
the Pennypack, making the little valley or gentle vale of
Huntingdon creek. West of the Pennypack, where there
appears no sandstone, the limestone is seen running on
alongside of the gneiss.
*See the sheet maps of 06, and the small map, Fig. 14, on page 39, C6.
fit is impossible to find its southern edge anywhere, see C6, page 41,
therefore it cannot be accurately measured.
jSee fig. 25, C6, page 45.
OLD GNEISS OF BUCK RIDGE. 87
4. The west end of the sandstone outcrop at the Penny-
pack seems (from the strike of the beds) to be sharpened
to a point. The same is noticeable at the east end of the
sandstone outcrop at Waverly Heights. Some would
account for the non-appearance of the sandstone in the
interval, by suggesting that the sandstone had not here
been deposited on the gneiss, which would account for the
limestone resting against the gneiss. But an irregular line
of crush faulting would afford an equally good explana-
tion; and such a. line of faulting seems called for by the
thinness of this belt of limestone, and by its shortness also;
for otherwise why should not the limestone run as far as
the sandstone does? And, as the limestone is, say, 2,000
feet thick in the Chester valley, why should it not make
a much greater show on the south side of Buck ridge?
Other considerations (hereafter to be presented) add testi-
mony to the existence of a great fault.
The Buck ridge range of syenite gneiss, then, has been
pushed up since the deposits of the sandstone and lime-
stone were made ; and through them as overlying deposits.
The syenite gneiss strata were, of course, under water when
the deposits upon them were made. It follows, then, that
any syenite fragments in those deposits could not have
come down from the Buck ridge strata, but must have been
brought from some syenite land at that time out of water.
Where, we know not ; certainly not the Welsh mountain
district, nor the "range of the Highlands, for they also were
under water. Perhaps from Delaware county, where the
syenite areas are large and we have no positive testimony
to the fact of their being then submerged, although it is
hard to imagine them otherwise. It is idle to look far afield
elsewhere.
The Buck ridge range of syenite gneiss, however, could
hardly have been pushed up thus in a quiet manner, by
simply sharing in the general elevation of a 50 or 100 mile
broad region of which it was ojae of the mountain ridges.
For, in that case, the sandstone and limestone deposits would
have been lifted also in a quiet manner upon it with their hor-
zontality or seabottom-slope-dips preserved. The steepness
88 GEOLOGICAL SURVEY OF PENNSYLVANIA.
of their present dips and their frequently vertical posture
shows that the Buck ridge was not lifted but squeezed up;
squeezing also the sandstone and limestone beds in its own
folds. Therefore, we must suppose that to some extent its
own folds correspond to their folds; or, in geological terms,
that they lie to that extent conformably upon the gneiss
strata.
This, however, a long and elaborate study of the whole
ground (represented by the arrows, &c. on Mr. Hall's sheet
map) shows plainly enough that they do not. The sandstone
and limestone folds sometimes correspond to folds in the
gneiss, and sometimes they do riot; and many of the strike
and dip details in the gneiss are evidently inconsistent with
the folds in the sandstone and limestone.
We must conclude, therefore, that the azoic country had
been subjected to movements previous to the age of the
sandstone deposits, folded, elevated and depressed,
weather-beaten and eroded by streams, and sculptured into
a region of hills and valleys, which had to be resubmerged
in order to receive the sandstone and limestone deposits
upon its worn and irregular surface.
The eastern portion of the Buck ridge, i. e. in Bucks
county, shows no sign of an anticlinal arch structure. All
the dips are towards the south, at high angles (75, 78, 80)
all across from the sandstone on its southern edge to the
border of overlapping mesozoic at its northen edge. On
the Neshaminy, however, the belt (two miles wide) is a
regular arch, with steep south dips at its southern edge, a
25 south dip near its middle, and vertical north dips at its
northern edge. Three miles further west, a section through
Feasterville shows just the reverse, 63 and 65 N. dips on
its southern edge and 75 S. dips on its northern edge; so
that one would think that Buck ridge was here an azoic
basin. Four miles further west, along the Pennypack,
where the belt is 2 miles wide, the gneiss is vertical or
(overturned ?) 80 N. at its .south edge, and then has 56,
70 and 65 S. dips for 1 miles, with nothing visible along
its northern edge ; and this is within half a mile of the end
of the sandstone basin ; so that we have south dips in the
OLD GNEISS OF RUCK RIDGE. 89
gneiss in direct prolongation of the north dips in the sand-
stone.
It is needless to illustrate further the fact that the sand-
stone does not He conformably upon the gneiss, in the sense
of the earliest history, but only in the sense of the later
history. And here it is necessary to point out a geograph-
ical fact which seems to remove the movements of this
later history far away from the azoic ages and bring them
down to the very end of Palreozoic time, to the close of the
Carboniferous age, the date as we know of that general
movement which produced all the folds of middle and
western Pennsylvania and the whole belt of Appalachian
country from New York State to Alabama. This geo-
graphical fact is the extraordinary straightness and
peculiar direction of the south edge of the Buck ridge belt
from the Delaware river at Trenton to the Delaware county
line, as shown on Mr. Hall's sheet map.
The south edge of the Buck ridge (marked by the vertical
or steep south-dipping sandstone and limestone, and
further west at the Schuylkill by serpentine beds) runs
first S. 80 W. 2J miles, then S. 62 W. 6 miles, then S.
79 W. 18 miles (to within one mile of the Schuylkill), then
S. 61, W. 5 miles (to the Delaware county line).
Nothing in Pennsylvania is more remarkable than this
long line of 33 miles, divided into four parts, two of which
have a common strike of 61, 62, and the other two a com-
mon strike of 79, 80, especially when we consider that it
represents a sudden plunge vertically downward and
southward (with or without fault) of one great system of
rocks beneath another ; for one of these strikes is almost
exactly parallel with that of the great plunge of the whole
Palaeozoic system of formations vertically downward and
northward into the Pottsville coal basin, sixty miles dis-
tant to the north, along a line (of even greater length) in a
direction S. 62 W.
The significance of this line is intensified by another,
which is undoubtedly in some way connected with it, viz :
The long straight line of the vertically-plunging limestone
(marble) beds at the south edge of the Chester county
90 GEOLOGICAL SURVEY OF PENNSYLVANIA.
valley, the strike of which is S. 74 W. for 45 miles west of
the Schuylkill river.
Generalizations become more dangerous as they become
larger ; but it is impossible to shut the eyes to the fact of a
grand parallelism of the anticlinal and synclinal folds
throughout Eastern Pennsylvania, produced by a hori-
zontal movement from the southeast ; or to the fact that the
system of parallel folds as a whole is itself parallel to the
special uplift of the azoic belt of Buck ridge which we have
been describing in the detailed manner which its import-
ance justified.
The historical azoic question raised by all this parallel-
ism is this : Were the Palaeozoic sediments shoved north-
westward on the Azoic floor, adjusting their gigantic pli-
cations upon it without regard to its own previously pli-
cated condition ; or, did this azoic floor consist of a
system of parallel mountain ridges which decided the par-
allel direction of and located and increased the Palaeozoic
folds ; or. was the real folding accomplished in the azoic
floor itself, the Palaeozoic formations merely sharing in
the -movement ; or, was the whole movement a complica-
tion of additional azoic crumplings below, with new pal-
CBZOIC foldings above ? These alternative hypotheses must
be discussed more fully when we come to the history of the
palaeozoic ages ; but it was necessary to allude to them in
advance in drawing attention to the remarkable line of
the Edge Hill or south border of the Buck ridge azoic
belt, and especially the most remarkable part of it, viz:
the 16i-mile straight S. 80 W. line, against which abuts
diagonally the Philadelphia gneisses.
The Buck ridge old azoic (syenite) belt crosses the Wis-
sahickon at the complicated bend of the creek a mile west
of Chestnut Hill; not as a ridge, but mouldered away to
the level of the stream, and only 400 hundred yards wide.
Thus it runs on a mile and a half further west to Barren
Hill; then a mile and a half farther west to the Schuylkill
river at Spring Mill, where it is just one mile wide. The
river after crossing the limestone valley strikes the hill belt
OLD GNEISS ON THE SCHUYLKILL. 91
of syenite, turns east and flows for a mile at its foot to
Spring Mill, and then turning at a right angle southward
cuts through it between bluffs of nearly vertical syenite
rocks for a mile.
Here the dark hornblendic rocks are pretty plainly
arched, although most of them are vertical, or dip very
steeply northward (as the sandstone and limestone strata do
which face the north side of the ridge); but obscure south
dips are seen on the southern side of the belt, where the
Philadelphia system abuts against it along a line of fault,
at the first brook above Lafayette station. All the ex-
posures from here down the river past Manuyunk and Phil-
adelphia belong to the Newer Azoic system of mica-schists
and micaceous gneisses to be described in the next chapter.
In Delaware and southern Chester counties the old
syenite azoic areas are so irregular in shape that they can
only be described by reference to the geological colored
county map.* As defined by Mr. Hall they appear as on
the accompanying sketch map, by which it will be seen
that their irregular outlines are produced by the partial
removal of the overlaying Philadelphia system of micaceous
gneiss. The whole district is a low rolling hill country no-
where more than about 500 feet above tide level ; and the
older gneisses being more easily decomposed, their areas
are somewhat sunk beneath the general surface, and sur-
rounded by the indefinite, gently sloping escarpments of
the borders of the micaceous gneiss areas. Only one
syenite area has a well determined east and west extension,
between Bryn Mawr and West Chester, with an outlying
area further on, crossing the Brandy wine. Chester creek
makes long exposures of the syenite, which appears also
on the Delaware state line and in the northernmost county
of that state
4. On the Schuylkill River.
Prof. Rogers' description of the syenite belt where it
crosses the Schuylkill river is given on page 76 of his geol-
ogy of Pennsylvania, 1858.
*See them represented, as defined by Mr. Hall, in a plate on page vii of
the preface to Report C4, on Chester Co., 1883.
92 GEOLOGICAL SURVEY OF PENNSYLVANIA.
The "harder feldspathic gneiss " is first seen (ascending
the Schuylkill) north of the soapstone quarries, dipping
southward 70 and even steeper; and then northioard 45 to
55, making a sharp anticlinal arch, up through the broken
center line of which has flowed a strong dyke of syenite
gneiss. Passing the blue prophyroidal gneiss quarries the
strata are lying nearly flat for say 1,500 feet, and then turn
up and stand nearly vertical, being closely compressed into
numerous narrow folds, all the way past the Wm. Penn
iron furnaces, nearly to Spring Mill, at the sharp bend of
the river, where the valley limestone appears.
He describes in detail (on page 75) the character of the
strata from the dyke northward; commencing at a small
dyke, 100 feet south of the end of the long tangent of the
Norristown railroad, which follows the east bank of the
river. His description may be divided into the following
parts :
(a) Dyke of syenite, small, composed of pinkish feldspar
and quartz; next north of which come
(b) Gneiss rocks, dipping 80 > N. 20 W., composed of
feldspar, quartz and hornblende (with some mica), coarsely
crystalline, evenly bedded with parallel lamination (not
minute or very continuous) dipping 80 > N. 20 W.
(Some beds have feldspar in excess and may be called por-
phyries.) Similar massive gneiss cut by the Reading rail-
road on opposite river bank. Distance along railroad 160
feet.
(c) Dyke of syenite (about 100' north of first dyke).
coarsely crystallized pinkish and white feldspar, with a
much less proportion of quartz, and a considerable amount
of large specks of finely granular (imperfectly crystallized)
hornblende. Dyke 10' thick. Contact with gneiss makes
a plane dipping 70.
(d) Gneiss, massively bedded, bluish gray (feldspar,
quartz, mica, occasionally some hornblende), many beds
prophyroidal, feldspar appearing in large insulated
blotches. Granite injections in gneiss near the syenite
dyke.
Extensive quarries. Bold nose of hill at bend of river.
OLD GNEISS ON THE SCHUYLKILL. 93
Dip of gneiss for the first 250' regular, 45 to 50 > N.
20 W. Then rather suddenly flattens to a small angle.
Dip of gneiss at 900' from the quarry, gently south.
(e) Interval between " the small quarry" and the south
end of Wm. Penn furnace No. 2, 387'. Here
(/) Gneiss massive, dark-blue, streaked and spotted (with
lens-shaped white blotches) ; composed of feldspar and
dark blue mica, in alternate slightly wavy laminae, with
lens-shaped concretions of pinkish feldspar. In some of
the bands these lumps are so abundant as to make the
rock porphyroid. Other bands finely laminated, the laminae
being in delicate, parallel, slightly wavy, bluish black and
pinkish white streaks, according to the relative proportions
of the dark mica and pink feldspar. The rock contains
some quartz, and occasionally some hornblende. Dip
(under furnace) 90.
(g) Gneiss (at N. end of furnace No. 2) feldspar mica ;
some of it minutely banded ; no feldspar lumps.
(k) Trap dyke (266' north of north end of furnace No. 2),
very hornblendic; thickness, 8'.
(i) Gneiss (421' north of north end of furnace No. 2) same
as (/); some beds with feldspar lumps, but fewer and
smaller than in (/); all more minutely and evenly lamin-
ated than (f)\ a real gneiss, but more like altered clay-
sandstone. The feldspar weathers mealy, chalky.
(/) Dip at north end of Old furnace No. 1. 60 >.
(k) Gneiss (100' north of north end of Old furnace No.
1\ feldspar- mica; exposed for 170' ; dip at south end of
exposure, 80 >.
(I) Gneiss (?) (330' north of north end of Old furnace No.
1; with feldspar lumps and specks rounder than those
of (/); finely streaked; looks less gneissic and more sedi-
mentary; strike S. 70 W. (pointing across the river to the
ferry house opposite Spring Mill); dip, 90 >; visible thick-
ness (in exposure) 100' ; ranges along the base of the hill
slope from ferry house up the river bank to Merion furnace
opposite Conshohocken.
The rock mass (1) conforms to the vertical gneiss (&) in
strike and dip, but is more earthy and less crystalline, and,
94 GEOLOGICAL SURVEY OF PENNSYLVANIA.
in fact, looks so different that Prof. Rogers feels author-
ized to place it at the base of the palaeozoic system, lying
immediately upon the gneisses (&) all in vertical posture.
The difficulties of structure are great, perhaps insupera-
ble. If the gneisses be closely folded and the folds pressed
together, sp^as to make one dip, and there be no clue to the
character of the last or northernmost fold, it becomes im-
possible to tell whether (I) lies upon or beneath (&) ; for, if
the last beds of (&) are rising northwards, then (Z) under-
lies ; if falling, then (I) overlies. Mr. Rogers regards the
horizontal middle part of the belt as a basin, but it may be
the flattened top of a grand arch ; in which case, all the
vertical gneisses of the northern side of the belt are going
down together, and this is the only view to be taken of
them in harmony with their extension eastward and their
encircling at Willow Grove the sandstone and the limestone
of the valley.
Another difficulty arises from the abundance of mica in
the masses (/) (g) (i) and (#) and especially (d) in which
hornblende is only an occasional element. In fact, only di-
vision (5) of the whole belt is distinctively a hornblende-
syenite. This difficulty will be felt when we come to de-
scribe the Philadelphia azoic belt lying alongside and
south of this Buck ridge belt and supposed to be a differ-
ent system, chiefly if not exclusively on the ground of its
exceptionally micaceous character.
As for the two "dykes" of syenite (a) and (c) containing
little or no hornblende, they may be integral members of
the series. But if they be true igneous dykes they are
merely additional examples of what we meet with in the
Highlands and Welsh mountain regions.
The trap dyke (7^), very hornblendic, belongs to a very late
time of disturbance during and at the close of the deposit of
the Mesozoic brown sand and shale, when all our largest
trap dykes were ejected from the interior as black lavas,
and the whole region of middle New Jersey and southeast-
ern and southern Pennsylvania, in fact the whole wide
belt of the Atlantic seaboard, was shattered and rifted by
continental earthquakes on the grandest scale.
ARE THE ARCHAEAN ROCKS SEDIMENTARY ? 95
CHAPTER X.
Are t?te Archcean rocks sedimentary?
The alternations of feldspar-gneiss beds with hornblende-
gneiss beds is as easily explained as the alternation of hard
sand-rock beds and shale beds among the sedimentary
rocks; or as the. alternation of limestone and magnesian-
limestone beds in great limestone formations.
The feldspars are combinations of the silicate of alumina r
with silicates of lime, soda and potash,- and a little magne-
sia and iron.
The hornblendes are combinations of the silicates of
magnesia, lime and iron, with more or less silicate of al-
umina, and little or no soda.
The chemical analyses of both the feldspars and horn-
blendes show an infinite variety of these combinations ;
which means an infinitely various mixture of the six sili-
cates of alumina, lime, soda, potash, magnesia and iron ;
as might be expected when rivers bring down sand and mud
from a country of all sorts of rock, mixing them on the
way in all possible proportions, and laying them down in
beds of all possible thicknesses, shapes and order of super-
position.
Where the pure quartz sand was in great excess, the rock
became a quartzite. Where the alumina was in excess, a
massive feldspar rock was afterwards produced. Where
the quartz was simply in excess of the alumina, a quartz-
feldspar syenite gneiss was the consequence. Where there
was a considerable charge of potash and a small charge of
iron, the deposit became a quartz-feldspar mica granitic
gneiss. Where magnesia and lime were abundant, horn-
blende crystals were formed, if the deposit did not origin-
ally consist of rolled hornblende crystals, obtained from
some weathered country composed largely of hornblendic
rocks.
96 GEOLOGICAL SURVEY OF PENNSYLVANIA.
In a word, given sediments of sand and mud, composed
of coarse and fine particles of quartz and feldspar, some of
them from a country poor in magnesia, others from a
country rich in magnesia, there must result alternations of
felsitic, micaceous and hornblendic gneisses, in beds of
every thickness and thinness, and in every variety of
grouping.
If, in the upper part of a great formation feldspathic
gneiss beds predominate, while in its lower part hornblendic
gneiss beds predominate, such an arrangement ought to
indicate that the drainage of the country which supplied
the materials was at first more magnesian or dolomitic, and
became less so afterwards. And if a great formation with
few micaceous beds be succeeded by a great formation of
mica schists, such an arrangement Ought to indicate another
change in the drainage system, viz., an increase in the
quantity of potash with iron in the river waters.
Throughout the Cambrian, Silurian, Devonian and Car-
boniferous ages such changes in the drainage system of
the continent which furnish the numerous palaeozoic sedi-
ments of middle and western Pennsylvania certainly took
place, or else we should not now have that remarkable pile
of dissimiliar formations, arranged in no assignable logical
order, and composed of an infinite variety of combinations
of coarse and fine grains of quartz, of the different feld-
spars, and of limestones with more or less magnesia and
iron. We have a right, therefore, to suppose such changes
of drainage to have occurred in pre-Cambrian time. On
this supposition, and granting the possibility of the partial
or complete re-crystallization of sediments with a total
destruction of all traces of organic life (if such existed), it-
becomes an easy matter to explain the alternations of
syenitic, hornblendic, granitic, micaceous and garnetiferous
gneisses and schists, with clay slates, mica slates, talc
slates and even with such serpentine beds (hydrated sili
cates of magnesia and iron) as cannot be proved to have had
a volcanic origin.*
*Even Professor Bonney admits this distinction.
THE ARGUMENT FROM THE MICROSCOPE. 97
The argument from the microscope.
There is a new school of geologists who trust to the
microscope for deciding whether an apparently bedded
mass of crystalline rocks were originally sedimentary
strata, or whether they were ancient outbursts or out-
flows or overflows of molten rock-glass taking on the ap-
pearance of stratification in the course of their lava-like
movement.* Such geologists take a totally different view of
the order of the old gneiss system rocks, and reject its chro-
nological subdivisions into Lower, Middle and Upper Laur-
en tlan. Their point of view is strengthened by the acknow-
ledged fact, that the whole Laurentian country from Lake
Superior to the shores of Labrador, northern New York
and much of New England is traversed by vast dykes of
massive (unstratitied) syenite and granite cutting the
bedded rocks and each other in all directions both vertical
and horizontal. Such masses or dykes of unstratified rock
in the highlands of New Jersey have already been re-
ferred to.f
At Kennedy's granite quarry, in Delaware county.
Radnor township, near Wayne station (a good photo-
graphic view of which is given on plate XXXVIII of Re-
port of Progress 05). no stratification can be made out by
the eye, and the syenite mass looks like an eruption from
below.
In strong contrast to this is the fact that at the Leiper
"granite" quarries, so called, in Ridley township (shown
in plates 16 to 22 of the same report.) the original sedi-
mentary stratification is unmistakable. But here we are in
another system of rocks which has no certain connection
with the Laurentian, as will be seen hereafter.
How much of the Laurentian system is sedimentary and
how much of it volcanic may never be exactly defined; but
the mere fact that one kind of rock can be seen cutting or
penetrating the other is the strongest argument for the gen-
niness of both, in spite of opposite theories of the general
*Rhyolitic, from the Greek verb rhein, to flow.
fThe granite of Richmond, Va., is of this kind.
7
98 GEOLOGICAL SURVEY OF PENNSYLVANIA.
origin of the whole, and in spite of any revelations which
have been or may hereafter be made by the microscope ;
with regard to which last, it may be also said, that the
microscopic examination of a transparent slice of azoic
rock may lead two observers to opposite conclusions under
the influence of two opposite prejudices, the one believing
at the outset that his specimen comes from a volcanic rock,
the other that it is from an original sediment subsequently
metamorphosed.
The argument from olivine.
A case in point occurs in Mr. F. D. Adams' report to the
Canada survey (in 1885) on microscopic inspection of thin
sections of a labradorite rock from the Upper Saguenay
river, flowing through the typical Norian region. In the
sections he could see grains of olivine, each having two
skins, an inner of pyroxene (?) and an outer of actinolite
(or hornblende), the whole being encased in a matrix of
lime-soda feldspar. The rock at large, from which the
sections were made, was composed of lime-soda feldspar,
olivine and some scattered grains of titaniferous (?) iron
ore. Now since olimne* is one of the universally recog-
nized volcanic glasses, abundantly expelled from modern
volcanoesf ; and since it is of frequent occurrence also in
older lavas, basalts and trap dykes, both in the form of
grains and small masses, long crystals and balls; and since
its golden-colored transparent crystals (chrysolite) also is
found in modern and recent lavas, \ the conclusion has been
drawn that the Saguenay rock formations taken as a whole
have been originally in a molten condition, and that the
olivine grains were the lirst to solidify while the envelop-
ing feldspar mass was still in the condition of molten glass;
in other words, that the silicate of magnesia solidified in
*A pale olive green opaque silicate of magnesia and iron (^3 sil., ^ mag.
and ^ iron.
fSee especially accounts of the Hawaiian islands, and of the Challenger
dredgings in the Pacific.
jThose found in sand at Expailly in France (Dana) probably came from
the Auvergnese basaltic beds.
THE ARGUMENT FROM OLIVINE. 99
grains first, and the silicates of lime and soda as the sur-
rounding rock afterwards. The enveloping zones or skins
of each olivine grain seen under the microscope would then
be the products of a slow subsequent process, by which the
surface of each grain (silicate of magnesia and lime) lost
some magnesia and became ^.pyroxene or augite ; while the
surface of the enveloping feldspar gained some magnesia
and became an actinolite or hornblende (silicate of mag-
nesia, lime and iron); both the inner zones of pyroxene and
the outer zone of actinolite being minutely crystallized in
tibers crosswise. Similar grains with double skins (the
outer hornblende) were described by Tornebohm,* as seen
in Swedish gabbro rock (an ancient crystalline, granite-like,
magnesia-lime-soda lava) the feldspar of which is usually
taken to be labradorite, and some varieties of which contain
an abundance of olivine. f
It is easy enough to see how a grain of strongly mag-
nesian silicate might act on and be affected by its en-
velope of lime-soda silicate to produce in time intermedi-
ate skins or shells of magnesia-lime-soda silicate by the
gradual mixing of the three elements along the contact
surfaces. But it is a risky thing to dogmatise an opinion,
1, as to how the grains were first formed, and 2, as to the
nature of the action and reaction between the grain and its
envelope. While it may be safely accounted probable that
the magnesia was concentrated by the fiery fusions of
the mass; and while it seems almost positively certain that
the fibrous zones could not have been cross crystallized
around the grains until after they had been fully formed;
we know too much of cold aqueous concretionary structure
in sedimentary rocks (e. g. oolites in the magnesian lime-
stones of No. ItJ:) not to make the aqueous formation of
the olivine grains a possibility. And then, the aqueous
alterations of minerals seen going on at a low tempera-
ture in the hardest crystalline rocks, at all depths of per-
meation, suggests the possibility of the cold aqueous for-
mation of the skins of the olivine grains.
*Neu. Lehr. fur Min., 1877, page 303, Adarns.
t A. Geikie's Text Book of Geol., page 150, 1882.
JCambro Silurian.
100 GEOLOGICAL SURVEY OF PENNSYLVANIA.
The granular condensation of the overcharge of magnesia
in a magnesian silicate mass is illustrated by Dr. F. A.
Genth's discovery in 1874 that grains of chrysolite are dis-
seminated throughout the whole mass of bronzite (iron-
bearing enstatite) forming Castle Rock in Delaware county.*
The bronzite mass is a silicate of magnesia and iron (57,
36, 6). But the grains of chrysolite have twice as much
magnesia and iron to the silica as the rock has which en-
velops them. In studying Castle Rock repeatedly I could
not quite convince myself that it is stratified, and there-
fore do not deny that it may be a volcanic dyke. Bur on
the other hand it is an integral part of the long belt of ser-
pentine strata which crosses the county; therefore it ought
to be sedimentary. But this belt of Delaware county ser-
pentine rocks does not belong to the older gneisses; it be-
longs to the mica schist series to be discussed hereafter;
therefore, the question of the volcanic origin of Castle
Rock does not directly affect any question respecting the
stratification of the older syentte belt which passes just
north of it.
The point to keep in view is this, that the genuineness of
the stratification of the older gneiss rocks is not impugned
by any amount of volcanic disturbance and intrusion to
which they may have been subjected; nor by any number
of massive granite dykes, bosses or layers of gabbro;t nor
by any amount of olivine discoverable in the area of coun-
try which they occupy.
The scarcity of olivine in the older gneisses can be appre-
ciated from the fact that in the long course of the history
of the geological survey of Canada its accomplished chem-
ist and mineralogist, Dr. Hunt, never saw (or at least never
reported finding) olivine in the Norian gneisses, although
he found it in some (Norian ?) boulders in New Hampshire
which were supposed to have come from Canada in the ice
age.:}: When Mr. Adams says that it "occurs abundantly
*Report of Progress B, page 163.
fSuch as the Gabbro formation of Lake Superior, which, however, is
placed above the gneiss by western geologists.
JAdams, Am. Nat, Nov., 18a5, page 1088.
THE ARGUMENT FROM SERPENTINE. 101
in the anorthosite of many parts of the Sagnenay area,"
and that he has found it also in a hand specimen from old
rocks near Dolin's lake in New Brunswick, such discoveries
leave the question of the aqueous or igneous origin of the
great gneiss formation as a whole still unanswered; for it
is supposable, and will be to many minds probable, that
the observed occurrences of olivine are referrable in all
cases to dykes or layers or bosses of igneous rock ejected
through and between the recrystallized sedimentary gneiss
beds, and not to the constitution of the gneiss itself.
The argument from serpentine.
It is needless to discuss the vexed question of the origin
of serpentinous rocks if we recognize the fact that they
may be of various kinds and have more than, one origin ;
some of them being sedimentary, others volcanic, and yet
imitating each other in the same way as the granite gneisses
and granites imitate each other.
In Pennsylvania we have no notable serpentine beds in
the Highland, Welsh mountain, Buck ridge, Delaware
county older gneisses. A discussion of the serpentine beds
of the mica schist series on the Schuylkill and west of it
would properly find its place in describing that series.
But as Mr. T. D. Rand has argued in the most forcible
manner for the assignment of these serpentines to a place
in the older gneiss series, not only in Delaware county, but
also in Northampton county, it is better to give the facts
here. In the proceedings of the Academy of Natural
Sciences of Philadelphia, November 24, 1886, pages 393,
407, and in the annual report of the geological survey of
Pennsylvania for 1887, Mr. Rand's views may be found with
illustrative maps and sections.
Of the two parallel serpentine belts that cross the
Schuylkill river (1) above and (2) below Lafayette station,
the (2) belt (with steatite} cannot be traced (west) beyond a
bend in the Black Rock road (one-half mile north of the
P. R. R.) The first belt is conspicuous at Rosemont
station (P. R. R.), but no farther. A (3) belt commences
LIBRARY
UNIVERSITY OF CALIFORNIA
SANTA RARRARA
102 GEOLOGICAL SURVEY OF PENNSYLVANIA.
on Meadow brook f mile east of Darby creek and runs on
westward. It was always doubtful to which belt (1) or (2)
this should be assigned. In 1885 Mr. T. D. Rand* "found a
distinct outcrop on the Roberts road, on the property of
Colonel Joseph F. Tobias, or of Dr. E. H. Williams, with
fragments in the soil of the former to the northeast. The
belt is very narrow, arid the valley of a small creek seems
to occupy nearly the same line." The outcrop is about
half-way between the Rosemont (1) exposure and the
Meadow brook (3) exposure and seems to settle the ques-
tion, f
The Edgehill (eurite) rock seems to outcrop 100' to 200'
from the serpentine on the Roberts road. The two occupy
here the same relations as they do near Radnor station, on
the other (N.) side of the Laurentian axis.
The Delaware county serpentines.
Castle rock, four miles north of Media, in Delaware
county, is a confused mass of plates of that species of
enstatite rock:}: which contains iron (bronzite) and which,
after imbibing water (chemically) turns into serpentine
rock (composed chiefly of silica and magnesia. ) On the
eastern side of a brook flowing south there are outcrops of
serpentine which indicate the continuance of the mineral
towards the Schuylkill ; but at the west end of the Castle
*Strike N. 30 E., dip 50 S. 60 E. ; mica schist, adjacent, strikes N. 40
E., dip 6508.50 E.
fThis outcrop is somewhat south of the Kosemont outcrop line and indi-
cates some change in strike, or a throw, or an echelon structure.
Jin Bucks county, near the Neshaminy, between Scottsville and Rock-
ville, at Vanarsdalen's quarry of crystalline limestone (interbedded with
hornblendic gneiss and charged with plumbago) among the numerous
species of crystals some contain percentages of magnesia, but none come
under the head of magnesian silicates proper. (Report B). Near the
mouth of the creek, at Flushing is an outcrop of enstatite rock, bedded and
dipping 10, the relations of which are not understood. (Report C6, p. 60.)
Mr. Salom, when Dr. Genth's pupil, found that between 5 and 10 per cent
of the Castle rock was soluble in dilute chlorhydric acid, and composed of
silica, 45 ; mag., 31.6 ; ferrous oxide, 19.4 ; lime, 3.9, representing dissemi-
nated grains of chrysolite; the insoluble 90 to 95 per cent was composed of
silica, 56; mag., 29; ferrous ox., 12; lime, 1.2, closely agreeing with the
composition of bronzite. Genth's Rep. B, 1875, p. 64.
THE ARGUMENT FROM SERPENTINE. 103
rocks a cultivated outspread of gneiss land soil shrouds the
geology of this singular place in mystery.*
There is a range of abandoned quarries extending from
Media W. S. W. past Lenni for miles, f Other ranges tra-
verse the county. C. E. Hall's sketch map in C4, preface
page v, shows more than 50 spots marked serpentine. It
is noteworthy that no'ne of them are in the Older (syenitic,
liornblendic) gneiss regions. All of them are in the interval
regions of Newer (micaceous) gneiss, the equivalent of the
Philadelphia belt. Nor are any of them in the South Valley
Hill belt of mica slate. :{:
The Chester county serpentines.
Serpentine outcrops are very numerous in Chester county.
Thirteen are enumerated in Report 04, pages 62, 63. Brin-
ton* s quarry is a grand exhibition of serpentine, and from
this quarry 500,000 cubic yards of the rock had been taken
before 1880, the largest being 3 feet square and 16 feet long.
In 1880 6,000 cubic feet of rock were moved, valued at
$10,000.
Dr. Frazer makes the general remark that "the serpen-
tine under no consideration has any direct connection with
the series of hypozoic and palaeozoic strata, or strata of pri-
mary origin.
The serpentines near Baltimore are said to furnish under
the microscope ample evidence that originally they were
*Mr. E. B. Harden has made for me photographic pictures of the mass as
it appears on all sides and in various lights. I have myself made a careful
contour line map of it, with pencil sketches ; but I could come to no certain
conclusion whether its apparrent bed-plates were or were not cleavage
planes. It may be synclinal, or it may be a dyke.
fSee also notes on the minerals of the county by Col. Joseph Willcox, in
C4, p. 346.
{Mr. Hall and Mr. Rand are thus directly opposed in their structural
views respecting the Serpentine. Dr. Frazer agrees with Mr. Hall in iso-
lating the Serpentine from the Archaean, but he advocates its connection with
the hydromica and chlorite series.
Report 04, page 289. Prof. Rogers notes serpentinous geodes in the
Welsh mountain gneiss, at Warwick mines, Report C4, page 238. Fine
specimens of serpentine have been found in the mines on Fritz's island near
Reading, at Topton, and at the Wheatfield, Boyerstown, Ruth and Jones
mines in Berks county; but no serpentine beds. See Reports D2 and D3.
104 GEOLOGICAL SURVEY OF PENNSYLVANIA.
trap dykes, holding a rhombic pyroxene, with or without
olivine. *
A similar conclusion was reached by Prof. F. D. Chester,
of Dover, Delaware, in studying the large belt of serpen-
tine on the state line in Chester county;f and he was led to
regard all the serpentines of Chester county as alterations
of rocks containing a rhombic pyroxene, either enstatite
or bronzite. The great mass of Castle rock, unchanged
enstatite rock in Delaware county can be seen passing on
eastward as a serpentine outcrop.
The Lancaster county serpentine.
The two remarkable belts of serpentine in southern Lan-
caster, passing over into Maryland, are described in detail
by Dr. Frazer in his Report C3, pages 26, 89, 177, 190.
Wood's celebrated chrome mine is in the southern belt
in an oxbow of Octoraro creek just within Little Britain
township. In Fulton township the serpentine ridges are
called "barrens." Up to 1877 about 90,000 tons of
chrome-iron ore had been taken. The mine was then 720
feet deep and yielded 500 or 600 tons of the ore annually.
The serpentine country through which the ore vein runs is
unstratified and about three quarters of a mile in breadth.
The ore strikes S. 78 W. The sandy chlorite slates to the
north of the mine dip S. 50. The rocks southeast of the
mine are hornblendic, and " a region of syenite commences
on that side "(Glenn). The same kind of difficulty here
encounters the geologist as in Northampton county,
whether he is disposed to connect the serpentine structur-
ally with the older hornblendic gneiss (syenite) system, or
with the newer gneiss (mica schist) system, or with the
still later chloritic (phyllite) system.
*Dr. G. H. Williams, of the Johns Hopkins University, on the Peritodites
and Serpentines of Baltimore.
t Letter, Oct 23, 1886. The mother rock of this belt appears to consist of a
rhombic pyroxene, probably bronzite, associated with a variable amount of
diallage, both minerals largely altered intolightamphibole aggregates, gen-
erally tremolite, partly actinolite ; and these are found in all stages of alter,
nation into a true chrome-serpentine, the direct product of alteration of
pyroxene, as described by Drasche in the Tyrol.
THE ARGUMENT FROM SERPENTINE. 105
The Northampton county serpentine.
The serpentine of the old Wolf quarry of Chestnut Hill,
Northampton county, seems to be not an originally bedded
deposit, like limestone, but an alteration product in the
white tremolite* quarry-rock (belonging to the hornblendic
or amphibole gneiss series), composed chiefly of silicate of
magnesia and lime. The silicate of magnesia after im-
bibing water has separated from the mass into veins and
lumps and scattered pseudomorph crystals of pure serpen-
tine. The lime has also separated in the iorm of veins and
masses of snow-white crystalline carbonate of lime (calcite).
It is possible to trace on the face of the quarry, in the
space of a few inches, the gradual transformation of the
pure white tremolite rock into a mixed stone, composed
mainly of serpentine, tremolite and calcite. The steps of
the process is observable in the thin slices under the micro-
scope, the tremolite crystals being broken up into bundles
of fibres traversed by irregular canals of serpentine.^
It was always an interesting question whether the ser-
pentine beds of Chestnut hill belonged to the Highland
gneiss or to the limestone of the valley ; \ but Mr. Rand
seems to have set the matter at rest by his observations in
the gap of the Delaware above Easton and in the gap of the
Bush kill west of the river.
Five soapstone (steatite} outcrops are exposed and four
of them have been quarried, all dipping steeply southward
enclosed between solid ribs of gneiss one or two hundred
feet thick. |
*See Genth's Report B, 1874, page 67. On page 64 he notes that the " Wal-
lastonite " of Easton is tremolite.
|G. P. Merrill, in Proc. U. S. National Musenm, Vol. VII, 1890, page 600,
where an analysis of the tremolite by Eakins is given : Sil. 58 ; Mag. 26 ;
Lime 12 ; Alum., Potash, Sod 4.
jSee Rogers' Geol. Penn., 1858, Vol. 1, p. 94, and Report D3, Vol. 1, 1883, p.
79.
T. D. Rand. Notes on the genesis and horizons of the Serpentines of S.
E. Pa. in Proc. Acad? Nat. Sci., Phila., March 25, 1890, page 95.
II South-dipping rnagnesian limestone outcrops border the river for a mile
above Easton to within 200 feet of the first exposed steatite or talc-slate bed,
which is not thick, has no visible hanging wall, but a foot- wall of gneiss.
The second one is immediately below the first and in the gneiss ; one mass
106 GEOLOGICAL SURVEY OE PENNSYLVANIA,
Chestnut hill is the western end of one of the Highland
ranges of New Jersey, severed by a steep and picturesque
gap cut through it by the river. Its beds of gneiss dip all
one way, southward, as the limestone beds do to the south
of it. There is no appearance of anticlinal structure in the
ridge.* Its crest, straight and sharp, is made by a massive
rib of gneiss, dipping at the river .31; at its highest point
(700' A. T.) 59, on the road 30, at the Bushkill gap 40,
43, 48, 60, further west 28, all southeast ; no northwest
dips anywhere, until its western point sinks beneath the
around-lapping limestone country, the nearest outcrop of
which dips 12 S. W. That the whole ridge is a mono-
clinal uplift is confirmed by the first limestone dip (28, N.)
seen at the Bushkill gap abutting against the lowest visible
gneiss dipping 48, S. E. f The talc-schist or soapstone beds,
and the serpentine (picrolite) beds are not of the age of
valley limestones (magnesian though many of these be) but
belong to the more ancient gneiss formation of the South
of it among many (5'-6' long) nearly pure talc schist at one end, at the
other apparently unaltered qartzose gneiss. Two hundred feet north of
the second appears the third, quarried for 100' up the slope ; both walls
gneiss, fallen blocks of the hanging wall showing change from granulite to
steatite. The fourth and much larger one is 300'-400' further north ; inter-
val, all (?) gneiss. The fifth 200'-300' further north ; interval all gneiss,
<one rib very massive, making overhanging cliffs, has been much quar-
ried). Beyond this, more gneiss ; dips obscure, but nearly vertical ; hill
crest more than 400 above the river. Incredible that these four outcrops
should be tightly-compressed synclinal folds of a talc schist formation over-
lying the gneiss. They must be conformably interbedded layers in the
( Lauren tian) gneiss. (Rand.)
*A11 this is noted on Prime's admirable contour-line map of Northampton
county in Atlas to D3, Vol. 1, 1883, sheets 1 and 2.
fit is not absolutely necessary to suppose an upthrow fault along the
northern base of the ridge, for a 28 dip would shoot the limestone high over
the ridge. Nor is it a mere "brushed up" dip, for all the observed limestone
dips along the'Bushkill for a mile up (and along the Delaware as far) are in
the same N. W. direction, towards a synclinal axis of considerable length.
Although the ridge itself is a very ancient eroded monoclinal, it became the
core of a subsequent overarching limestone anticlinal, which included all
the Lower Silurian formations, probably the Upper Silurian series also, anil
possibly the whole Palaeozoic system to the top of the Coal Measures. There
has been tire* enough since the Coal Age to remove it all, and exhibit once
more the original pre-Silurian or pre-Cambrian topography.
THE AEGUMENT FROM LABRADORITE. 107
mountain highlands whatever it may be.* And this agrees
with all Mr. Rand's observations of the serpentines of Del-
aware and Chester counties, which he shows pretty clearly
to be interbedded among the ancient gneisses of that
region.
On the other hand, the serpentine belts of Lancaster
county and Maryland are assigned both by Frazer and
Keyes to the phyllite system of rocks, which belong to the
Philadelphia belt of newer gneiss ; and the serpentine and
steatite of the Schuylkill are placed by Rogers and C. E.
Hall at the top of that newer gneiss system.
In Newfoundland, as in Pennsylvania, no extensive dis-
play of serpentine is known in the Laurentian system, nor
is crystalline limestone found. Lime, magnesian minerals,
and mica are remarkably absent from the great overlying
formation (Huronian) ; lime showing only in cross veins,
and magnesia only at one place, as steatite and asbestos, in
seams. Guided by the fossils Mr. Murray came to the
conclusion that the serpentine formation overlaid the
Levis (Quebec group) and were overlaid by the Hudson
river group, etc. unconformably, so that they were even
overlaid in places by Devonian. This possible identity of
the Newfoundland serpentine formation with our great
magnesian limestones (No. II. Chazy?) would bring it into
the neighborhood of the Northampton county serpentine
beds, north of Easton.f
Genthite has been found at the Lafayette soapstone
quarries, in small, bright, emerald green crusts, showing
its characteristic stalactitic structure. This proves the
presence of nickel in our serpentines.:}:
The argument from labradorite.
Labradorite rocks are unknown among our older gneisses
*Another good argument both for this and also for the monoclinal struc-
ture of Chestnut ridge, is the fact that no serpentine or talcschist or steatite
is to be seen anywhere along the northern side of theridge, or at its north-
ern base.
t Alex Murray, Canada survey, in Geol. Mag., March, 1879, p. 139.
}H. C. Lewis, May 12, 1885, in report of Acad. N. S. Philada. meeting in
Amer. Nat., Sept., page 929.
108 GEOLOGICAL SURVEY OF PENNSYLVANIA.
in Pennsylvania; and about this it is necessary to say some-
thing.
The eastern range of the Canadian mountains, through
Labrador to the ocean shore, is a country of massive and
schistose gneisses, many of which are made up of quartz
and labradorite feldspar. * This feldspar is essentially a
silicate of alumina, lime and soda (53 : 30 : 12 : 5), and might
be formed in a metamorphosed sediment just as well as any
other feldspar, provided the drainage of that sediment was
from a limestone region. It is a'frequent constituent of
modern volcanic lavas, and is found also in some ancient
trap-dykes and porphyries; but so are several other feld-
spars. It is in itself no proof of the plutonic origin of the
East Canada gneisses.
It is still a question what relation in time the great Lab-
radorian (Norwegian or Norian) system of gneisses holds
to the West Canada Laurentian (Ottawa or Granville) sys-
tem of gneisses.
Now, although the Norian rocks are commonly called
Upper Laurentian, it is possible to consider them as two
geographical areas of one and the same system; in which
case the abundance of labradorite feldspar-^ in the eastern
area would be an accident of drainage. On any other
hypothesis it is difficult to explain the absence of labrado-
rite gneiss from the range of the New York, New Jersey and
Pennsylvania highlands ; for it looks as if we had in this
range the upper part of any Laurentian system which
could be established on anything like a sedimentary basis
of argument.
The argument from marble.
White crystalline limestone beds are interleaved with
the gneiss rocks of the New Jersey highlands all along
their northwest border, and some are pure marbles (96.50 :
1.13 : 1.30 : 0.30) ; others nearly pure dolomites (53.00 :
42.26. 3.50 alum, sfnttox. iron : 0.50 silica and insoluble). ^
*With hornblende, hypersthene and magnetic iron.
fOr rather of the whole group of plagioclase (soda and lime) feldspars.
{Cook's An. Rt, 1864, page 15.
THE ARGUMENT FROM MARBLE. 109
Prof. James Hall, however, published at the Albany
meeting of the A. A. A. S., in 1876, his opinion that the
crystalline limestones of northern New York are no part
of the Laurentian system, but are of later age.*
The azoic marble beds of New Jersey furnish precious in-
formation for studying those of Pennsylvania.
In Warren county, N. J.. at Lower Harmony are exten-
sive quarries. An acre of marble was exposed in 1871,
without penetrating more than 15' of strata; indistinctly
dipping steep S. E.; gray, in some places banded with al-
ternate dark and light lines; with scattered nodules and
masses of soapstone (steatite) and hornblende; some graph-
ite ; a very little pyrites in places. In the deepest parts of
the pit the stone is more solid and free from these min-
erals, f
In the Jenny Jump range of highlands the Rose Crystal
Marble quarry (50x50x25 yards deep) have exposed 30'
of rose-colored marble beds, dipping 80 N. 75 W.
Quarry beds, white, flesh-colored, rose-colored; with green-
black hornblende, black mica and occasional crystals of
black tourmaline ; calcite predominates largely ; stone can
be burned for lime; polishes well, showing the other min-
erals ; blocks 8'x3'x2' got free of seams or joint flaws.
The overlying beds (to the west) are pearl gray. The
underlying beds (to the east, 100' thick as exposed are
ordinary white limestone, none colored.*
Two belts of azoic white crystalline limestone or marble
traverse New. Jersey in its Highlands. The Pequest belt
has beds so thick and persistent that it can be located by
color on the geological map of New Jersey; and its rare
and beautiful minerals are fully described in the geology
of New Jersey. The Ramapo belt is smaller and remark-
able for containing serpentine everywhere, in such quan-
tities (in places) as to spoil the limestone for lime -burn -
*See Amer. Jour. Science. See also C. E. Hall's report on the Adirondack
rocks ("Laureutian magnetic iron ore deposits of N. N. Y.") with a geol.
mapof Essex Co. in Rt. of State Geologist for 1884 (No. 161, page 31).
fCook An. Rt., 1872, page 26.
jCook An. Rt., 1872, pages 27, 28.
1868, pages 309, 326.
110 GEOLOGICAL SURVEY OF PENNSYLVANIA.
ing; both massive and also fibrous (cTtrysotile), especially
both at Mountville and also near Winokie.
This union of serpentine with marble shows two things:
1, that the azoic lime deposits were in part highly magne-
sian, and, 2, that they were in part highly siliceous.
Under favorable circumstances the hydrous silicate of mag-
nesia (serpentine) has been generated in small quantities
in our mixed magnesian and non-ma gnesian limestone beds
of No. II.*
The sedimentary origin of the azoic marble beds, as or-
dinary lime-magnesia muds, can hardly be doubted.
Included beds of syenite-gneiss in the body of the marble
mass and regularly inter stratified, with the marble beds
complete the proof, and carry the conclusion one step
further, that the gneiss was itself also an ordinary mixed
sand-mud deposit, like all the sandy shale and sand rocks
of after ages which have remained uncrystallized merely
because they have not been subjected to the proper
process.
In Pennsylvania the Highland gneiss areas do not show
their marble beds enough to be well studied. The beds are
not thick enough to encourage mining in competition with
the marble quarries of No. II along the Chester valley. But
where they are thus exposed in southern Chester county
they reveal the same facts as in the New Jersey High-
lands', f
In New Jersey the Pequest marble belt has been so ex-
tensively quarried that the story is plainly told. Take for
instance the section S. W. from Hardystonville,^ where
two gneiss formations 10' and 80' thick respectively, and
about 200' apart, are regularly interstratified with about
1,000' of marble beds. One such example would suffice,
but many others present themselves. There can be no
*As at Reading, see last loot note on page 103, above.
fSee Report C4
{Wood cut in Geol. N. J., 1868, p. 313.
These alternations of gneiss and marble beds are finely exposed at
Mine Hill ; on the Snufftown road, southeast of Hardystonville ; on the
Deckertown road over Pochunk mountain ; east of that road near Ryer-
son's ; and many other places. The interstratified gneiss beds appear in
THE ARGUMENT FROM MARBLE. Ill
more doubt of the sediment of gneiss in this azoic marble
formation than of the sediment of St. Peter's sandstone in
the magnesian limestone of the west, or of the great sand-
bed groups in No. II throughout Nittany valley in central
Pennsylvania, and near Chambersburg in Franklin county.
It is evident that the agents which changed lime mud into
marble, changed sand mud into gneiss. Consequently the
great gneiss formation which contains in its own body the
mnrble beds, was itself as a whole originally an' ordinary
sand mud formation.
The marble beds vary greatly in crystallization, texture,
color, composition and imbedded minerals ; generally
coarsely (rhombic) crystalline ; sometimes finely granular,
or even amorphous to the eye ; color grayish, pinkish, but
generally pure white, with lustrous cleavage; sometimes
dull, hard, siliceous. Graphite scales nearly everywhere
disseminated through the mass. Mica quite common.
Many other rare minerals occur in it.
Why is azoic marble so abundant in New Jersey and not
in Pennsylvania ? A true answer to this question would
throw great light on our gneiss system.
It looks as if a far greater thickness of gneiss comes to
the surface in New Jersey, and as if the great azoic marble
formation must be deep in the Pennsylvania underground.
Part of the vast gneiss system holds these marble beds,
and another part does not. This is evident from the fact
that the first or front range of gneiss Highlands in New
Jersey only shows four small outcrops of marble.* The
second range contains no known outcrop of marble. The
third range (and the interval bet ween the second and third)
makes a magnificent display of marble beds of great length
all parts of the marble belt. Very frequently they are such local deposits
that after running a few yards, or a few rods, they more or less suddenly
turn into limestone. Some have a length of 100-200 yards and are from 120
to 300 feet in thickness. One at Ryerson's is 360' thick (or wide). Most of
the gneiss is a hornblende syenite, without mica ; some of it contains mica.
The trap dykes at Mine Hill cross the whole breadth of marble bed, gneiss
beds, sandstone beds and blue limestone beds of No. II ; but they are very
thin, only a few inches wide.
*Wynokie, two ; Montville, one; Mendham, one. Cook, Geol. N. J., p.
309.
112 GEOLOGICAL SURVEY OF PENNSYLVANIA.
and thickness.* The average width of the marble belt is
one- third mile, rarely exceeds one- half mile, but across the
New York state line widens to two miles. But approach-
ing Pennsylvania "the range seems to thin out and at last
disappear towards the southwest."f
Certainly there is nothing to compare with this in the
Highlands west of the Delaware river. Now everything
combines to show that our highland gneisses never rose to
as high a level as those of New Jersey ; and, if we were
quite sure of the structure, we must justly infer that our
gneisses from Reading to Easton were those of an upper
division of the old Azoic ; a lower division coming up to
the present surface in New Jersey and New York, bringing
with it the great marble formation. That would explain
things. But the structure of the highlands is too obscure
to allow us to rely on any such generalization. Therefore,
we must accept as a possibility that the white limestone
formation may not have extended westward originally.
Any third hypothesis that the white marble beds are local
plutonic or volcanic extrusions like outflows of lava cannot
be seriously entertained now by any one.
But a fourth source of explanation for the small local
exhibitions of marble in gneiss \ may be found in the fact
of the close plication of the rocks; the limestone being pre-
served in short, sharp, collapsed synclinal troughs; or, as
in the case of the Brandywine marble quarry, projected
upwards as a sharp-tongued anticlinal fold.
But in some cases the white limestone is merely an ele-
*Twenty miles long, from Mts. Adam and Eve and Round Hill, in New
York, along west side of Vernon valley, by Franklin furnace to Sterling
hill. No palaeozoic rocks seen. At Franklin the blue limestones of No. II
lap over the marble beds. This state of things keeps on through New York
state. Geol. N. J., p. 310.
fProf. Cook, G. of N. J., p. 312.
jLike the " detached outcrops surrounded by gneiss at North Vernon,
described by Prof. Cook on pages 313, 314, and a number in Pennsylvania.
One of these detached patches at North Vernon, N. J., seems to be 900' long
by 600' wide; the other is 1,700' long and " quite narrow;" a third is 5,000'
long and 900' wide, with a good deal of gneiss included in it. It seems
hardly possible to avoid the inference of complication and repetition in such
a case.
See my sketch in Report of Progress C4, page 239.
THE. ARGUMENT FROM APATITE. 113
ment in the gneiss, and what is of more importance " it
predominates largely in some of the beds and enters some-
what into the composition of the iron ores worked" at the
Roseville mine.*
The argument from apatite.
The Laurentian age of the highland gneiss is testified to
by the occurrence of regular apatite (phosphate of lime)
magnetic iron ore beds enclosed in the gneiss, as in the
Adirondack mountains of northern New York.
In New Jersey, in 1871, at Ferro-Mont (Dickerson M.
Co.), a bed 8' thick was opened, dipping 65 S. E., mixed
magnetite and gray-white apatite, between regular walls of
gneiss in which little if any apatite exists. Some parts of
the bed show alternate layers (or lenses) of magnetite and
apatite. Of the whole mass 50 per cent in bulk (35 per
cent in weight) is apatite, f There is too much phosphorus
for the lime ; some of it is therefore combined with the
iron. There is a little quartz, feldspar (orthoclase) and
occasional spangles of brown mica.
*Cook, Geol. of N. J., page 316. The marble at Lockwood is nearly pure
carbonate lime, very coarsely crystalline, with scales of graphite distributed
through it, and beds and horses of gneiss in it. Its whole length is only
360' and its greatest width 50'. The white crystalline limestone (91 per cent
carb. lime) along the Paulin's Kill contains graphite, galena, &c., and in-
cludes alternating beds of gneiss (page 317). The Andover white (some-
times pinkish) limestone, highly crystalline, is so pure that only traces of
magnesia are detected in it (page 318). The Decker's Pond marble beds
alternate with gneiss beds of the same strike and dip (page 318). But in the
fourth (Jenny Jump or Oxford) belt the marble seems to be more mixed
with magnesian minerals. It is a great formation, with an outcrop 4,000'
wide but with inter stratified gneiss beds. The alternation is finely exposed
at the east end of the 20 mil outcrop. The gneiss cairies magnetite beds, and
copper ore. The marble carries steatite, <fec. The whole formation is in
fact a dolomite, and one is tempted to think it a metamorphosis of No. II ;
especially seeing that some of its members are flaggy, flaky and finely crys-
tallized (pages 319, 320). This is the Marble Mountain outcrop at the Dela-
ware river.
fCook, An. Rt, 1871, p. 35. An average specimen gave 54 of mag. iron;
17.21 lime ; 14.91 phosphorus (=31.90 apatite). A picked piece gave 53.85apa-
tite. The two minerals can be separated by crushing and washing, or by
magnetic machines. Soluble phosphoric acid can be made, worth in 1871
14 cents a pound.
8
114 GEOLOGICAL SURVEY OF PENNSYLVANIA.
In Berks county, Pa., apatite of a bluish color is found
in very small white hexagonal crystals with the magnetite
at the Jones' mine.* and at the Mt. Penn mines. f But no
minable beds of it have been found; only scattered crys-
tals in the gneiss of southeastern Pennsylvania. :{:
The original character of the magnetite beds is indicated
by the fact that hydrous phosphate of iron (cacoxenite)
are found in the brown hematite (limonite) iron ore mines
at Conshohocken, Montgomery county ; at Chiques, Lan-
caster county; and that minute quantities of phosphoric
acid (I in the form of cacoxenite) are found in almost all
the limonite beds of the state. Also the hydrous phos-
phate of alumina (wavellUe) occurs in Trimble's iron mine
in the Chester valley, East Whiteland; also in concretions in
the York county Peach Bottom slates ; and at Chiques in
limonite.
It may be objected that the phosphorus in limestones and
limonites is a derivative from that in the gneiss; or else
that it comes directly from animal life- forms (as in the case
of recent bog-ores); and, therefore, that it cannot indicate
the origin of the magnetic beds. But if other and stronger
arguments for the genesis of magnetite from brown hema-
tite beds be at hand, then the distribution of apatite crys-
tals and masses in iron-bearing gneisses can be adduced as
an argument for viewing the gneisses themselves as sand-
mud sediments, and their included magnetite beds as orig
inally bog-ores or more probably beach iron sanfts.
*D3, Pt. 2, page 394.
t Rogers' Geol. Pa., 1858, II, page 716.
jGenth, Report B, page 138. Blue green hex. prisms at McKinney's
quarry near Gennantown, in massive orthoclase; at Megargee's paper mill;
atFrankford; at Grey's ferry and West Philadelphia; at Leipersville and
at Beattie's mill, Delaware county; at Unionville, Chester county. Fine
yellow-green hex. prisms and conchoidal masses in Londongrove township,
Chester county; in the limestone of .Bernard's quarry, West Marlboro'; at
Nivin's limestone quarry in North Garden. Bluish hex. prisms and grains
and masses in Van Arsdale's limestone quarries, southern Bucks county.
Straw and honey colored hex. prisms, with pyramid and basal plates, with
crystallized dolomite, in Prince's soapstone quarries, Lafayette, Montgom-
ery county.
Genth, B, 144.
THE ARGUMENT FROM IRON ORE. 115
The argument from iron ore.
The great beds of magnetic iron ore in the Highlands
show unmistakable evidences of sedimentary origin; there-
fore, the gneisses in which they lie, and into which they
graduate by insensible stages, must be of sedimentary
origin. That is the plain and simple argument.
In New Jersey, boring for magnetic iron ore is recom-
mended by Prof. Cook on the supposition that the beds
are practically continuous down the dip as along the strike,
which is undoubtedly judicious. He assigns a useful limit
of 2,000' in depth, in view of the expenses of hoisting. In
our ignorance of the depth underground he well says that
"a single boring might develop the existence of more ore
than is mined in the whole state in the course of a year."*
The replacement of ore by rock, and the alternation of
bands of magnetite and gneiss are well shown by Cook in
his report of 1873, pages 78 to 87. The ore is never in
veins cutting the gneiss, but always" in interstratified beds
following the strike; report of 1874, page 34. The alternate
banded structure is shown by Cook in the report of 1874,
page 23; and again at the Ten Eyck mine in the report of
1876, page 52.
The hanging wall ore is clean ; the foot wall ore is mixed
with feldspar, quartz and hornblende. As in the case of
the apatite mines of northern New York, so here, were the
ore a solidified fluid filling a fissure the pure ore would not
occupy one side and the impure ore the other, but the pure
ore would be in the deep filling the whole chasm, and the
impure ore would have occupied the whole chasm above it,
as the cinder floats on the metal in an iron furnace. In the
case of the Adirondack mines the apatite occupies the
hanging wall part of the vein ; but in the New Jersey High-
land mine the impurities occupy the foot-wall portion of the
vein. This signal distinction points still more strongly to
original sedimentation.
The connection of the New Jersey magnetite beds with
*An. Rt, 1872, pages 24, 26.
116 GEOLOGICAL SURVEY OF PENNSYLVANIA.
white chrystalline limestone, or marble, tells the same story
in another form.
The Schuler ore pits, near Roxburg, in the Pequest belt
of N. J., show tine-grained magnetite (with much man-
ganese) in grey -white crystalline limestone, steep to S. E.*
The Roseberry ore, near Belvidere, is mixed with much
mica and blue shaley rock.
The Barton black granular ore has a little hornblende and
much dark micaceous gneiss.
The Shoemaker ore is a rock containing magnetite ar-
ranged in parallel lines with the usual gneissic minerals, f
The Redell ore is black manganiferous magnetite, non-
sulphurous, in contact with gray crystalline limestone.
The Raub ore, N. W. of Oxford furnace, lies close to the
crystalline limestone, if not in it.$
The magnetite vein at the Kanouse mine has close to it a
crystalline limestone containing a large percentage of ser-
pentine, and in contact with this (conformably) a grey
gneiss. (Cook, An. Rt. N. J., 1873, p. 28 V.)
The Marble mountain part of the Pequest belt of iron
ores in IS". J. is the most northerly, next the Great Valley
limestone formation, and its ores differ from those of the
other Highland belts. The. belt is a continuation of that in
Pennsylvania, and is therefore instructive for our geology.
The Marble mountain mine is especially interesting for
the fact that the ore is red hematite in a talcose (mag-
nesian) formation, included in or resting on gneiss, uncon-
formably: This talcose slate occurs in this Pequest belt
only and in no other in N. J.
The Titman shaft ore, S. E. of Bridgeville, is red hema-
tite, in a grayish red slate formation, lying between mica-
ceous and hornblendic gneiss on the south and common
blue magnesian limestone on the north, and "probably non-
conformable to both.||
*Cook, An. Rt. 1873, p. 73.
fCook, An. Rt 1873, p. 74.
jCook, An. Rt. 1873, p. 75, 76.
Cook, An. Rt. 1873, p. 72.
J|P. 76.
THE ARGUMENT FROM IRON ORE. 117
The Welsh and Inschow's lean manganiferous magnetite
is imbedded in grey white crystalline limestone (steep to
N. W.) holding hornblende, a little mica, and much
graphite, and some manganese. In one hole the ore was in
thin strings through the limestone, which itself held brown
garnet and serpentine.*
The Howell farm ore (10'wide) includes impure limestone,
but lies in or against a hard gray close gneiss country.
Near by the ore holds much calcite and graphite, f
*Cook's An. Rt 1873, p. 84.
fCook's An. Rt 1873, p. 86.
118 GEOLOGICAL SURVEY OF PENNSYLVANIA.
CHAPTER XI.
The Newer Gneiss of the Philadelphia Belt.
The Schuylkill river, after cutting through the Older
gneiss of the Buck ridge already described, makes a pic-
turesque narrow valley, bounded by low bluffs of newer
gneiss and mica schists as far down as the Gray's Ferry
bridge, in the south part of Philadelphia.
These rocks belong to one system and one age and have
a general moderate dip toward the north-northwest. So
that, if no reduction need be made for irregularities or repe-
titions, there must be visibly exposed along the river
banks more than 20,000 feet of strata. But they have been
subject to great pressure, as is shown by myriads of con-
tortions, by a perpetual variation of local strike and dip,
and by small faults, how many or how important it is dif-
ficult to determine with any accuracy. There may there-
fore be in reality no more than 15,000 feet, or even less.
Still, the mass is evidently so great, and in a large sense
so regularly and conformably stratified from the visible tog
of it at Lafayette station, to the lowest visible beds at Gray's
ferry, that the Lafayette station beds must have once risen
southward into the air to a height of 10,000 or 15,000 feet
above the present street grade of Philadelphia. In other
words, a mountain range of that height once extended from
Trenton, New Jersey, past Philadelphia, Baltimore and
Washington into the southern states.
This mountain range has been gradually washed- away.
The length of time requisite to accomplish such destruction,
slow as it must have been, is inconceivably great, a fact suf-
ficient of itself to prove that we are dealing with one of the
oldest geological rock systems of the world.
The mountain range, when at its full height, must have
presented cliffs of great height and steepness towards the
THE NEWER GNEISS OF THE PHILADELPHIA BELL. 119
Atlantic; cliffs representing the basset edges of all the
strata which we now see in succession along the river
from Lafayette station down to Gray's ferry. There is no
arch visible, and no evidence that the strata, after rising to
the full height, turned over and descended with an opposite
dip. For, if that had happened, southern New Jersey
would have now a geological character similar to that of the
Philadelphia belt, and the Delaware river would not have
established its channel on a course directly in front of and
across the mouth of the valley of the Schuylkill.
All geologists would agree in the belief that the line of
the Delaware from Trenton to Chester must be the line of
one of the greatest downthrow* faults which the earth-
crust has suffered ; and that the whole series of strata seen
along the Schuylkill exists now at a great depth under-
ground beneath the Cretaceous and Tertiary plains of New
Jersey, southern Delaware and eastern Maryland. In east-
ern Virginia and the Carolinas they spread out at the sur-
face. In the opposite direction they underlie middle New
Jersey and appear again at the surface at New York. Our
Germantown hills are the hills of Staten and Manhattan
Islands ; and the whole formation continues broadening and
rising east of the Hudson, through western Massachusetts
and Vermont, where it constitutes part of the great Green
mountain range.
The bottom of this system of rocks is unknown, because
concealed beneath the Delaware valley muds and the New
Jersey green sand marl formation. The lowest beds visible
are those at Gray' s ferry. They are very f eldspathic schists,
in a state of complete decay, being turned into a coarse
sort of porcelain clay or kaolin. From these Gray's ferry
beds upward the series may be examined along both banks
of the Schuylkill river, in the cliffs of Fairmount, in the
cuttings of the Pennsylvania R. R. on the west bank, in
those of the Reading R. R. on the east bank, in the road
*It would be more historically true to speak of it as an upthrow. For it is
quite possible that the movement upward which evidently took place on the
north side was not accompanied or balanced by a downward movement of
equal value on the south side of the fault
120 GEOLOGICAL SURVEY OF PENNSYLVANIA.
cuttings of the city park at Manayunk, at the quarries on
Wissahickon creek, and along the drive-ways to German-
town and Chestnut Hill. No better exposures of a great
rock sytem can be found anywhere.
Its three sub-divisions.
The lower, middle and upper rocks exposed along the
Schuylkill differ in general character sufficiently to justify
three sub-divisions of the system, named by Mr. C. E. Hall
in his report C6 : (1) The lower, or Philadelphia mica
schist and gneiss group; (2) The middle, or Manayunk
mica schist and gneiss group ; (3) The upper, or Chestnut
Hill garnetiferous schist group.
The course of the river Schuylkill in its traverse of the
whole belt is worthy of careful study.
From Spring Mill to the Falls of Schuylkill, 6| miles, its
course is almost a perfect straight line, square across the
strike, i. e., S. 45 E. In this distance it first cuts through
the Old (Laurentian Buck ridge) gneiss, one mile ; then the
Chestnut Hill group, 1 miles ; then the Manayunk group,
3 miles, and then half a mile through the upper beds of
the Philadelphia group.*
At the Reading railroad bridge (Falls of Schuylkill) the
Schuylkill makes a right-angle bend to the right and cuts
nearly along the strike, about S. 40 W. H miles to the
Columbia bridge, f
Then it makes a right-angle bend to the left and cuts
*The Wissahickon, the Schuylkill and the Brandywine all flow from the
low limestone Chester county valley into and through gneiss gorges on
their way to the Delaware. In the case of the Wissahiccon the act is start-
lingly bold, because accomplished by a small stream. But all the rivers of
he state do the same deed repeatedly. How do they do it ? The question
presents itself in view of every mountain gap in the state. It will be dis-
cussed further on in this report ; but it may be said here that when the
gorges of the Schuylkill, Wissahiccon and Brandywine were made the
Chester valley was at much higher level. Its lime rocks have been dis-
solved faster than the gneiss and its level lowered more rapidly.
fThis part of the valley corresponds to the low ground which runs for
miles at the foot of and in front of the Txermantown hills, past Nicetown
and the brickyards. At the Columbia bridge the river makes a bend around
the west foot of the hill on which the East Park reservoir is placed.
THE PHILADELPHIA (LOWEB) SUB-DIVISION. 121
nearly straight across the strike, S. 80 E. 2 miles, along
the dam and past Fairmount to Vine street.
Here it swings round again to the right past the Market
street bridge, and follows the strike 1| miles S. W. to
Gray's Ferry after which its meanders to the Delaware are
in river muds and have no regard for the underlying rocks.*
Had the Schuylkill prolonged its upper straight course
across the strike four miles further to the last gneiss struck
in the cellars of Kensington, at the edge of the river mud,
and made its mouth at the bend of the Delaware below Port
Richmond, we should have had 9 miles of continuous ex-
posures across the whole Philadelphia belt, say 50,000 feet
in breadth, dipping practically all one way, at angles never
less than 20, often over 50, and in places vertical. In
spite of all disturbances of the dip it is not an unsafe esti-
mate then which assigns to the whole system a thickness of
20,000 feet.f
1. Tlie PJtiladelpJiia (lower] sub-division.
The Philadelphia rocks show themselves from Grey's
ferry up to the mouth of the Wissahickon. The slope of
the strata is always up river, but with many contortions to
the right and left, sometimes through a quadrant of the
compass. In the steep wall of Fairmount, under the old
reservoir, the dip varies between 20 and 40. On the rail-
road opposite it is generally about 20. Further on through
the park it often rises to 50 and 60. At the foot of Lemon
hill the most curious and beautiful wavings and foldings
may be seen in the much-weathered and mouldered mica
schists, marked by thin streaks of milky quartz, which has
been deposited as a gelatinous solution in seams where the
twisted beds moved on one another and were slightly parted
here and there. The whole soil glitters with shining little
flakes of brown and yellow mica, set free from the mould-
*It is possible that the course from Market street to Gray's Ferry was de-
termined by some past condition of the terrace gravel deposits. But that is
not likely in view of the fact that it here repeats its conduct between the
Falls of Schuylkill and the Columbia bridge.
fWe shall see in the next chapter that the same system (probably) on the
Susquehanna, in York county, shows a similar thickness.
122 GEOLOGICAL SURVEY OF PENNSYLVANIA.
ering rock. Very few solid beds can be found, and the
surface stone is worthless. Even where quarries have been
opened the undecayed stone can only be used for the
roughest building purposes, although all cellar walls in the
older and much of the newer parts of Philadelphia have
been built of the grey micaceous gneiss. Railroad cuttings
through tough and apparently enduring rock become in a
few years mere ditches, with softened sides covered with the
micaceous clay into which the rock is converted by the
weather. This accounts for the lowness of the hills on both
sides of the river; and, in fact, for the disappearance of the
great mountain range which once occupied the Philadel-
phia belt country.
But among the grey micaceous gneiss beds and mica slate
beds occur numerous beds of hard hornblende-gneiss, which
is a good quarry stone and stands well. There are places
where the dark hornblende-gneiss beds and the light-grey
mica-gneiss beds are interleaved and alternate regularly,
showing that the hornblende-gneiss is a true sedimentary
rock and not in any sense volcanic.
Mr. Hall's description of the rocks of this group (H. D.
Rogers' "first belt") is as follows : "The common varieties
are grey schistose'gneiss, composed of quartz, feldspar, and
black or brown mica, and occasionally garnets, occasional
beds of black hornblende slate, and fine-grained sandy
gneiss." (C6, page 2).
#. The ManayunJc (middle) sub-division.
The exposures extend from the mouth of the Wissa-
hickon up to the mouth of Mill creek, three miles. But.
neither the one limit nor the other is well defined. The
separation of this group from that beneath it and that above
it is rather arbitrary. Its gneisses are, however, chiefly
micaceous ; fewer hornblende gneiss beds are seen. Yet
the weathered surfaces and the soils resulting from the de-
composition of the outcrops have a darker color than the
surfaces and soils of the Philadelphia rocks, a dark iron-
rust yellow, or brown, especially where the hornblende
slates run.
THE MANAYUNK OK MIDDLE SUB-DIVISION. 123
The dip is still generally northwest up-river, but with
numerous waves and folds in the bluffs and the railroad
cuts. One arch of considerable size may be seen in the Mc-
Kinney quarry on the south side of the Wissahickon at the
ascent of G-ermantown.* Here also the excellent quality of
the better varieties of gneiss is practically displayed. On
the north side of the creek at its mouth the convolutions
and sharp foldings of the schists plainly reveal both the
'mashing and the stretching pressure-strains to which they
have been subjected. f
Mr. Hall's description of the Manayunk group, which he
interpolated between H. D. Rogers' "first" and "second
belts," is as follows: ''Alternations of the above-named
varieties of gneiss (named in the Philadelphia group) and a
predominance of sandy gneiss, composed of quartz and a
small amount of feldspar and mica in minute flakes. Mica
schists and hornblendic slates alternate with finer-grained
gneisses, the mica usually light-colored " (C6, page 2).
3. The Chestnut Hill (upper} sub-division.
The exposures extend from the mouth of Mill creek for
half a mile up to the Lafayette soapstone quarries with a
constant general northwest dip, and these continue for an-
other half mile to a serpentine outcrop along the south
edge of the Bear Ridge older gneiss belt, but with reversed
(S. E.) dips. Therefore, there is here a synclinal basin, and
then a great fault, in 'which must be buried (against the
older gneiss mass) the Manayunk and Philadelphia sub-di-
visions.^:
The dips, both north and south, are however very steep
*This quarry is extensively worked for city use and is famous for its
specimen crystals of hornblende, orthoclase feldspar, chrysocolla, mala-
chite, bornite, chalcopyrite, heulandite, apatite, etc. The presence of these
copper and phosphorus minerals is noteworthy.
f A fine exposure of a double or S fold along the north Pennsylvania R. R.
above Shoemakerstown, is represented in Mr. Hall's section in Report C6,
page 2& The minor complications under the fold show how the schists
slid upon each other with a certain difficulty and much friction.
JAt least this is the best explanation of the structure which has been ob-
tained.
124 GEOLOGICAL SURVEY OF PENNSYLVANIA.
and often quite vertical ; and the strata are even more con-
torted than elsewhere along the Schnylkill.
The characteristic featiires of the group are its mica
schists crowded with garnets, its thin-bedded sandy
gneisses, its hornblendic slates, and its two ranges of ser
pentine beds. *
The Lafayette steatite or soapstone quarry has been
wrought for a century and is now regularly mined in gal-
leries. The rock dips steeply northwest. f It is part of a
line of serpentine outcrops which extends at least seven
miles in an almost straight (but not continuous) line from
Bryn Mawr N. E. to Chestnut Hill, crossing the Schuylkill
at the soapstone quarry, and the Wissahickon a quarter of
a mile below the gorge of older gneiss, where it is well-ex
posed on the road up to the village of Chestnut Hill 4
Another line of serpentine outcrops crosses the river half
a mile above the soapstone quarry ; is traceable only half a
mile east of the river; but west at intervals into Delaware
*Mr. Hall says in another place "this second belt" of Prof. Rogers' (that
part of it not included in my inserted Manayunk belt) is characterized by
the serpentines; soapstone; silvery micaceous, garnetiferous schists; light-
colored, thin bedded sandy gneiss, with disseminated light-colored mica in
minute flakes ;" and a very curious peculiarity of fracture, "the rock
breaking into long narrow chunks, comparatively smooth on their sides,
but excessively ragged on their ends; a style of fracture strongly resemb-
ling that of half-rotted fibrous wood." (Quoted from H. D. Rogers' Geol.
Pa., by Hall, in C6, page 2.)
As for Rogers' "third belt," it is the Bunk ridge Older gneiss. Hall
traced it in a straight line to the Delaware river and found it everywhere
overlaid on both sides by the quartzite ("Primal," "Potsdam," "Itacobu-
mite," "Eurite") beds, which, east of Willow Grove, Moreland township,
Montgomery county, are a coarse sandstone and conglomerate, holding
fragments of the older gneiss, principally the characteristic blue quartz and
syenite. ( C6, page 3. )
fThe soapstone quarry is about 100 feet wide, with walls nearly as high,
and so dangerous that tunnel work has been substituted. Thousands of tons
loosened by the decomposition of the magnesian substance fell with a great
crash when the Pennsylvania railroad company cut their new valley branch
across one end of the quarry. The tunnel work is about filteen feet wide
and as many high. A few hundred yards above the quarry a road ascends
to Roxbury by a hollow in the woods called Rockdale, from the great num-
ber of loose rock masses scattered and grouped about, some as large as
houses.
JSee Hall's large colored map on the scale of 5,000'-1" in C6, and text page
92. Also T. D. Rand's sketch map in Ann. Rept. 1886.
THE CHESTNUT HILL OR UPPER SUB-DIVISION. 125
county. This line of serpentine seems to outline the contact
of the newer and older gneiss. If the other serpentine belt
be in the axis of a synclinal, this one must be at least 2,000
feet lower in the series, i. e., supposing both to be bedded
and not volcanic rocks.*
The Chestnut, Hill fault.
The extension of the Lafayette serpentine belt eastward
far beyond the other to the north of it gives the key to the
whole structure of the Philadelphia belt between the
Schuylkill and the Delaware at Trenton.
All three sub-divisions are sliced off diagonally by a
fault.
The Chestnut Hill group, whether synclinal or monoclinal,
ends in a point at Jenkintown, 8 miles east of the Schuyl-
kill. The Manayunk group fines away to nothing between
the Pennypack and Pequessing creeks, seven or eight miles
east of Jenkintown. The Philadelphia group narrows more
and more, but reaches the Delaware at Easton.
In fact there is not a more remarkable feature of the
geology of Pennsylvania than the thirty mile Jong per-
fectly straight line of the Itacolumite (Eurite} vertical beds
which extends from the Wissahickon to the Delaware, and
against which the various members of the Philadelphia,
Manayunk and Chestnut Hill schists one after the other ef-
face themselves. If this be riot a great diagonal fault,
then all common proofs of such a fault may well be set
aside. t But it becomes of still greater importance when
taken in connection with the jifty-mile long straight line
of vertical uplift of the South Valley hill between the
Schuylkill and the middle of Lancaster county. Straight'
geological lines are a great rarity. Curves are the rule. A
straight line eighty miles long must mean something great.
It deals with huge thicknesses of formations, and with im-
*The steatite is probably an altered schist bed, for specimens can be found
showing stages of the alteration, and the hanging wall rock contains crys-
tals of staurolite altered into serpentine.
fM. Renevier's recent protest against such faults and advocacy of trans-
verse deposition in the rocks of Canton Valais, however well sustained at
La Tini6re, can have no force here.
126 GEOLOGICAL SURVEY OF PENNSYLVANIA.
mense depths beneath the surface. In the azoic rocks they
mean dislocations, down or upthrow faults. In the palaeo-
zoic rocks they mean anticlinal and synclinal folds of a
massive amplitude that take away the breath of the spec-
tator.*
Look at the folds in a lady's thin silk dress, then at the
folds in a heavy cotton shirt, then at the folds in a woolen
winter cloak. See how the system of innumerable delicate,
short and irregular crimples of the first passes into a
system of long, straight solemn lines in the last. The sedi-
ments of time are the dresses of the planet, and their com-
plications imitate the draperies of statuary. Therefore, the
strikes of the rocks are sure indications of both quality
and quantity of formations. If we had no other proof of
the immense thickness of the Philadelphia gneiss and mica
scbist system, this vertically erect and perfectly straight
long itacolumite outcrop would be~alone sufficient ; just as
the forty-mile straight line of the Bald Eagle mountain in
Lycoming, Centre and Clinton counties is sufficient proof
that the great fold of Nittany valley deals with 40,000 feet of
sediments as an integral mass, one and entire.
*For example, the synclinal of Pottsville and the anticlinal of the Orwigs-
burg valley in Schuylkill county.
THE PHILADELPHIA BELT WESTWARD. 127
CHAPTER XII.
The Philadelphia rocks in Chester, Lancaster and York
counties.
The structural obscurity of the azoic rocks of the region
bordering the state line between the Schuylkill and the Sus-
quehanna cannot be exaggerated. If the colored state map
published by H. D. Rogers in 1858 be compared with C. E.
Hall's colored county map of Delaware (1884), andFrazer's
maps of Lancaster and Chester (1878, 1881), it will be seen
how unsatisfactory is our knowledge of a district on which
three independent geologists of great experience lavished
years of patient field work, only to arrive at contradictory
conclusions respecting the relationships of some of its
large formations to one another, while they agree singularly
well in their special observations of local facts, which, after
all, are the only things of value to the public.
It is a region of excessive-pressure disturbance. Thou-
sands of smaller rolls, and some great waves, traverse it
from east to west. Its outcrops of gneiss, mica schist,
hornblende schist, argillite, quartzite, serpentine and lime-
stone dip at all angles and in both directions. The crump-
ling is complete. The alternations are infinite. Crystalli-
zation and metamorphosis have not only destroyed every
trace of fossil life forms (if any there were originally), but
changed the characteristic qualities of the rock itself. Sec-
ondary minerals have been produced abundantly. Groups
of strata are inverted, the older upon the newer. Faults in-
terrupt the run of the outcrops.
All this has been brought about by the general earth
movement northwestward which produced the huge anti-
clinal and synclinal rock- waves of middle Pennsylvania.
Measured by 'straightening out these waves the thrust from
the southeast has shoved the country at least forty miles
128 GEOLOGICAL SURVEY OF PENNSYLVANIA.
towards the Allegheny mountain, crumpling its stratifica-
tion into this labyrinth of confusion and altering its lithol-
ogy so as to deprive the observer of a clew through it.
If the distinction between the Older and the Newer Gneiss
be a valid one, the Older gneiss seems to disappear from
the surface going west from the Schuylkill into Chester
county, and the Newer gneiss seems to occupy the whole
field south of the belt of South Valley Hill hydro-mica
slate* in Chester, and south of the great limestone plain of
Lancaster county. Dr. Frazer assumes that it occupies his
broad Tocquan belt in York county. His sections along
the Susquehanna river are therefore of the greatest import-
ance for comparison with the Schuylkill river section. It
can hardly be doubted that the grey gneisses, mica schists,
etc. of southern York are the same as those of Philadel-
phia, Manayunk and Chestnut Hill, although no such sub-
division as Hall's has been made of them.f
I will therefore summarize Dr. Frazer' s descriptions of
the azoic formations in York county before attempting any
concordance of them with the Philadelphia rocks, or any
identification of them across the intervening counties.
The Newer Gneiss in York county.
The belt of azoic schists across which the Susquehanna
river flows, between Lancaster and York coilnties, is about
15 miles wide at the river, which enters the belt at Turkey
Hill and leaves it at Muddy creek. Low hillsides along the
river, with natural outcrops and railroad cuttings, show the
structure of the belt to be that of a broad fiat anticlinal arch,
its axis crossing the river at the mouth of Tocquan creek
(McCall's ferry).- There the lowest strata appear, the
highest being of course at the north and south edges of the
belt,
*Nothing has as yet been said in this summary report about the hydro-
mica slate belt, although it appears on the Schuylkill river opposite Con-
shohocken and ranges through Chester into Lancaster county, because it
can best be studied on the Susquehanna and in York county, and in Mary-
land.
fMr. Hall, in coloring his Delaware county map, abandoned the attempt
to represent the distinction between the Philadelphia and Manayunk
grc ups.
THE NEWER GXEISS IN YORK COUNTY. 129
Dr. Frazer's sections along both banks of the river, show-
ing north dips up river and south dips down river, gave him
a closely-estimated total exposed thickness of more than
fourteen thousand (14,400) feet.* How much more should
be added for the oldest members of the formation concealed
beneath the surface cannot be known, f
In York county the arch is not symmetrical, Tocqnan
axis being 10 miles from the northern and only five miles
from the southern border of the belt. But in Lancaster
county the belt is only about 10 miles wide and the Tocquan
axis is nearly central.
The Tocquan arch seems to sink southwestward through
York county into Maryland, and rise eastward through
Lancaster into northern Chester, where the Laurentian
gneiss comes up to and occupies the present surface.
The lower strata along the Tocquan anticlinal are thor-
oughly and coarsely crystallized. Those above them, to-
wards the north and south borders of the belt, are less per-
fectly crystallized, or in much smaller masses.
The lower strata are distinguished moreover by larger
amounts and larger specimens of muscovite, and more pot-
ash micas generally. The rocks are of lighter color, and
there is often enough feldspar to make true gneiss ; and
this is the case more and more approaching the Tocquan
axis. Toward the edges of the belt, that is, ascending in
the series, the strata become more magnesian, softer and
darker, usually greenish or yellowish green ; containing
large quantities of chloritic minerals, and cut by an extra-
ordinary number of white quartz dykes.:}:
*The sections are given in the Atlas to his Report of Progress CCC. This
belt of ancient rocks has suffered from all the earth movements of all sub-
sequent ages, and its originally regular stratification has been so warped and
fractured, compressed and bent, that scarcely two exposed plates of rock
agree in presenting the same dip or strike. Accurate measurements of
thickness are therefore impossible. But on the whole, the estimate given
in the text may be accepted with considerable confidence.
fDr. Frazer could find no rock strata on the Susquehanna to which he
thought the term Laurentian (either Upper, or Lower) would properly
apply ; in other words, none of the Chester and Delaware county gneisses
which have been called Laurentian.
JP. Frazer, Gen. Notes Geol. York Co., Proc. Am. Phil. Soc., Phila., Dec.
4, 1885, p. 395.
9
130 GEOLOGICAL SURVEY OF PENNSYLVANIA.
The whole belt seems destitute of metallic ore veins of any
kind, even iron. And what is equally remarkable, only
two very small local trap dykes have been noticed in it in
York county; one, near its northwestern border, on the
Maryland line, two miles east of Black Rock P. O., and the
other, on the Susquehanna river, three miles north of York
Furnace. It is needless to say that no trace of fossil life,
animal or vegetable, has been as yet detected in these crys-
talline schists. The country is one of low hills, well
watered and fertile.
A better understanding of this important belt of azoic
rocks will be got by comparing a description of them
lately published by one of the geologists of the United
States Geological survey.
The Newer Gneiss in Maryland.
The Azoic crystalline (Tiolocrystailine, or completely crys-
tallized) belt of York county, passes into Maryland and is
joined by the great crystalline belt of Chester and Dela-
ware counties, the two belts encircling and holding in a syn-
clinal the southwest end of the Peach Bottom phyllite belt.
These Maryland crystallines have been studied by C. B.
Keyesof the U. S. G. Survey,* and described as thoroughly
metamorphosed highly feldspathic sediments, penetrated
by vast quantities of eruptive materials often of the same
composition as the strata through which they break ; in
other words, eruptive granites cutting sedimentary gneisses ;
all together foliated by pressure, so that in parts of the area
they can hardly be distinguished.
The gneisses which can be certainly regarded as crystal-
lized sedimentary beds are thus designated :
a. Typical Motite and biotite muscomte (mica) gneiss,
highly feldspathic, and in thin parallel layers, as in the
quarries on Jones' and Gwynn's falls at Baltimore, cut by
biotite pegmatite dykes, and full of eyes, lenses, or chunks
of quartz. At Washington they hold well-characterized
conglomerate beds.
b. Muscomte (mica) gneiss, with but little feldspar, but
*See paper in Bull. G. Soc. Amer., 1891, Vol. 2, p. 309.
THE NEWER GNEISS IN MARYLAND. 131
full of garnet, staurolite, cyanite, fibrolite, rutile, etc., and
cut with innumerable white quartzite veins.
c. Mica schist, without feldspar, but with garnets, etc.,
full of white quartz veins ; apparently a local variety of b.
These are evidently the gneisses, mica schists, garnet
schists, and contorted and veined schists of Philadelphia.
There are other rocks which show little or no signs of any
original sedimentary disposition, such as:
d. Setter's ridge quartz-schist, or quartzite, extensively
quarried north of Baltimore, and affording at many other
places a definite geological horizon ; always perfectly foli-
ated by parallel muscovite mica layers, at variable distances
from each other ; with plenty of stretched and broken tour-
maline crystals in the foliation planes.
e. Orbicular quartzite, compact, fine-grained, with radi-
ating quartz crystals ; as at the Poor House quarry (along
the western edge of the Texas augengneiss area) and in the
Brooklandville marble.
/. Deer creek white conglomerate quartzite, in the center
of Hartford county, four miles long and less than half a mile
wide, marking a sharp, narrow 300-feet high ridge. Under
the microscope it is seen to be completely re-crystallized,
but showing to some extent the original pebbles, with a
secondary growth of wavy membranes of muscovite, large
radiating tufts of blue cyanite, chlorite, magnetite, tourma-
line, garnet, rutile. When better studied this may turn
out to be a basal conglomerate of the Peach Bottom phyl-
lite series, for its outcrop is just along the line which sepa-
rates the phyllite and gneissic areas.
g. Marble (highly crystallized magnesia-limestone, dolo-
mite) beds occur among these rocks, in irregular, sharply-
folded patches at Cockeysville and Texas in Maryland, as
in Chester and Delaware counties on the Brandy wine. Its
poarse-grained variety is called "Alum stone." It con tains
crystals of phlogopite, tremolite, white pyroxene, tourma-
line, scapolite, rutile.
h. The eruptive rocks are : (1) With a surplus of silica :
granite, granitite, hornblende granite, granite porphyry,
augengranite gneiss, quartz porphyry (felsite), graphic
132 GEOLOGICAL SURVEY OF PENNSYLVANIA.
granite (pegmatite) ; (2) With sufficient silica : gabbros (of
three varieties), norite, diorite, hornblendite and horn-
blende-biotite-quartz diorite; (3) With too little silica:
pyroxenite, cherzolite, cortlandite, and the resulting ser-
pentine.
The certain or probable eruptive rOcks cover half the
present surface area of this great belt, (Keyes, p. 310, 311.)
It is open to doubt, therefore, whether the large areas in
Delaware county colored on the map accompanying Report
C5 as Laurentian may not, when well studied, come to be
recognized as parts of the same eruptive system. For the
belt of gneisses, mica schists, garnet schists, with steatite
and serpentine and marble beds, which are so finely exposed
along the Schuylkill, Crum creek, Chester creek and the
Brandy wine, is evidently continuous through Bucks, Mont-
gomery, Philadelphia, Delaware, Chester and Lancaster
counties into Harford county, Maryland, and so south into
Virginia.
THE AZOIC HYDRO-MICA SLATE FORMATION. 133
CHAPTER XIII.
The azoic hydro-mica slate formation ; phyllite belts of
York and Lancaster counties; South Valley Hill slate
of Chester county.
The age of the South Valley Hill formation has been in
controversy. Studied at the Schuylkill and along the south
side of the Chester limestone valley, where its beds stand
nearly vertical, Dr. Frazer saw it descending beneath the
limestone to rise again in the North Valley Hill toward the
Lancaster county line. Mr. Hall, on the contrary, saw it
overlying the limestone, in two separate and distinct syncli-
nal basins, one of which he represents upon his atlas map
(sheet 3) crossing the Schuylkill and terminating at Marble
Hall and Barren Hill in Montgomery county.*
In Dr. Frazer' s cross sections from Quarry ville to the
Pequea, and from Marticsville to Neffsville, i. e., across
middle Lancaster county, a thin hydro-mica formation is
drawn rising and falling in many waves under the great
limestone formation (which includes clay slate or argillite
beds) ; and beneath it the great floor of gneiss. Sometimes
the gneiss is at the surface ; generally the limestone ; occa-
sional outcrops ofhydro-mica slate.
At Quarryville the Chester County Valley ends, not in a
point, but by swinging sharply round to the north and ef-
fecting a narrow neck connection with the most southern
point of the great limestone plain of Lancaster. The
structure is not quite comprehensible ; but the valley lime-
*The broad rounded end of this streak of slate between two streaks of
limestone is very suggestive of a spoon-shaped synclinal. At Gulf Mills,
west of the Schuylkill, dips of 80 N. and 85 and 65 S. show a synclinal-
Here also in the short nose are dips of 85 N. and 75 S. showing a syn-
clinal. But it is dangerous to construct curves out of such high dips; and
Dr. Frazer insists on reading the dips so as to convert the two synclinals
into two anticlinals. If Mr. Hall's reading is correct, then these slates must
be Hudson River No. Ill, as he makes them.
134 GEOLOGICAL SURVEY OF PENNSYLVANIA.
stone seems to end as a synclinal, in a trough of South Val-
ley Hill hydro-mica slate.
But the phyllite belts of York county are a long way off,
the northern one stopping (on the map) in the triangle made
by the Susquehanna and Conestoga above Safe Harbor ; the
southern one ending (on the map) eight miles south of
Quarry ville. There seems to be a probability that the South
Valley Hill slates are geologically connected with the York
county phyllites as one and the same formation underlying
the great limestone. In fact, as the South Valley Hill
slates are apparently several thousand feet thick, and as the
York county phyllites seem to be of equal thickness, we
should look for a great show of them in so complicated a
country were they geographically connected across Lancas-
ter county between Quarryville and Safe Harbor, or be-
tween Quarryville and Peach Bottom ; certainly all around
the edges of the great limestone plain of Lancaster ; whereas
that plain is edged with quartzite and gneiss. But not to
puzzle over this and other collateral conundrnms here, the
following description of the phyllites will suffice :
The main York county phyllite belt. *
As describe^ by Dr. Frazer, this extends from the Susque-
hanna river below Wrightsville (Columbia) to the south-
west corner of York county, in a gently undulating way
upon the map, and with a breadth of three or four miles.
The land is lower than the crystalline country to the south-
east of it, and the rocks are so decomposed that very few
outcrops are seen, which makes the geology obscure. Dal-
lastown, Loganville, Hetricks and West Manheim villages
are in this belt, and Glen Rock on the Northern Central
railroad is at its southeast edge where the southern branch
of Codorus creek issues from the gneissic belt of .the Toc-
quaii anticlinal.
This southeastern edge (the northwestern edge of the
Tocquan belt) is drawn on Dr. Frazer' s map, he says, not
in a precise manner, but as an approximation to the truth ;
*Creedner's term in general use in Europe for finely-leaved argillaceous,
or clay slate strata, of which roofing slates are a variety.
THE MAIN YORK COUNTY PHYLLITE BELT. 136
because the phyllite strata do not differ from the Tocquan
strata along the line as if there was an abrupt change from
a lower to a higher series, but as if both belonged to one
great series becoming more slaty or schistose upward. The
dividing line upon the ground is therefore less definite than
it had to be made on a colored map. It commences at the
river opposite Turkey Hill in Lancaster county, passes a
mile north of Windsor P. O. and a mile south of Dallas-
town to Glen Rock and Black Rock.
The strata are much folded and distorted as they descend
northward beneath the clay slate, quartzite, hydro-mica
slate, limestone and New Red strata, and rise to the surface
again, twenty-five miles to the northwest, at the foot of the
South mountain near Dillsburg in the northwest corner of
York county, where again they seem to lie on the older
schists, but are themselves covered by broken fragments of
quartzite and other rock- wash.
The Loganville trap dyke, four miles long, prolonged
north-northeastward (after the break of a mile) eight miles
further, crosses the phyllite belt and penetrates the over-
lying Silurian rocks beyond it. Patches of Hellam
(CMques] quartzite of Upper Cambrian age occur, suggest-
ing that it once covered unconformably and perhaps en-
tirely the phyllite belt; and the quartzite occupies a strip of
land along the northern edge of the belt, west of the river.*
Some limestone beds occur in this phyllite series inter-
stratified with the slates, as at Glen Rockf
*This fact by itself would make impossible the suggestion that the phyl-
lites, schists and gneisses are nothing but metamorphosed Silurian or De-
vonian sediments.
fSmall thin lenses of marble occur in the Sericite belt of Maryland, north
of the B. and O. R. R. The marble is extremely hard and of a fine, even
grain, the crystals almost requiring a lens to see ; at the Westminster quai-
ries, snow-white ; more often streaked with black, gray or red ; in contact
with the copper of Liberty and New London and the lead of Union Bridge.
These marbles of the phyllite (sericite) belt differ both from the uncrystal-
line blue limestone of Frederick valley and from the coarse (loaf-sugar)
crystalline magnesian limestones (dolomite marbles) of Baltimore county.
These last hold crystallized quartz-clay impurities, but the phyllite marbles
show narrow bands of sericite or chlorite schist. (Keyes, p. 307.) Fossil
shells, "well characterized," are reported to have been found by Prof. P. R.
Uhler in slaty bands traversing the Westminster quarries, which lie very
136 GEOLOGICAL SURVEY OF PENNSYLVANIA.
Iron ore deposits also occur in this phyllite belt, the
largest of which are the Brillhart and Feigley banks a
mile or two east of Loganville, which Dr. Frazer is disposed
to regard not as really belonging to the phyllite rocks, bm
as washings (segregations) from later formations which once
covered the phyllite belt but have been removed by the
general rain erosion of the country.
The southern or Peacli Bottom phyllite belt.
This borders on the southeastern side of the Tocquan
gneisses, and occupies a triangular area in the southeast
corner of York county between Muddy creek and the state
line ; and in it appear the Peach Bottom roofing slates.
If these are a part of the series, it is remarkable that they
do not appear in the belt of phyllites above described on
the northwest side of the Tocquan gneiss.*
It is quite evident that this phyllite area occupies a broad
synclinal, and that its strata are superimposed upon the
Tocquan gneiss series ; for the phyllite ends in a point in
Maryland surrounded by the gneiss, f and it seems to end
also in Lancaster county.:}: There can be no other ex-
planation of the geographical relationships of the phyllite
and gneiss areas. The gneiss area entirely surrounds this
phyllite area ; therefore, the phyllites must either rise on an
anticlinal or sink in a synclinal. The former supposition is
precluded by the anticlinal structure of the Tocquan belt,
near the eastern border of the phyllite belt, in 1880. Sent to the New Or-
leans exhibition, they were lost before any descriptions or identifications of
them had been made. (Keyes, p. 307.)
*There is a roofing-slate belt in the heart of the South mountains; the
quarries were long ago abandoned because their slate could not compete in
the market with the Peach Bottom slate. What relation in geology the two
bear to each other is not known.
fSee the frontispiece map of C. R. Keyes' paper in Bulletin Geol. Soc-
Amer., Vol. 2, p. 301. The point nearly reaches the Northern Central R. R,
25 miles from the Susquehanna river.
{See map of Lancaster county in P. Frazer's Report C3, Atlas, where the
phyllite area is seen extending to five miles from the river north of the
Little Britain, Lyles and Pleasant Grove serpentine belt. It does not come
to a point, as in Keyes' map, but has an indefinitely square transverse ter-
mination ; which merely indicates the fact that its geographical northeast
extension could not be properly mapped. See Chapter XIX.
THE PEACH BOTTOM ROOFING SLATES. 137
and the descent of tjie phyllites to form another belt on its
north border, extending across the Susquehanna eastward,
and across the state line to the Potomac.*
The phyllite belt is said by Keyes to "include the semi-
crystalline slates and finely fissile schists which compose so
large a portion of the Piedmont area in Maryland. They
are capable of sub-division into a great number of varieties.
They are beyond doubt argillaceous sediments which have
undergone a greater or less amount of mechanical (cleav-
age) and chemical (crystallization) metamorphism, though
they do not lithologically differ from beds which- in many
other localities are known to be of Devonian, Silurian, or
Cambrian age. Their most important mineralogical compo-
nent is a silky white mica (sericite or Kaolin), whose indi-
vidual scales vary greatly in size in different specimens.
This is sometimes wholly or in part replaced by green
chlorite, with inter-beds of chlorite slate. Quartz grains
are common \feldspar very rare (perhaps because changed to
white mica); iron, in red hexagonal plates (or rounded grains)
common, often so abundant as to make the rock an ore ;
minute tourmaline crystals very common ; microscopic
rut He needles everywhere abundant; ottrelite finely-de-
veloped in some beds. The phyllite cleavage is always per-
fect, and of a satiny lustre increasing in proportion to the
mica present, and of various shades of pale grey, green,
blue, purple and black (roofing slates). The original sedi-
mentation is attested by round grains and small pebbles of
various composition. Where least disturbed the slates are
jointed and cut by cross seams of chlorite or quartz ; where
more disturbed they are puckered and filled with veins and
eyes of quartz.
The Peach Bottom roofing slates.
As described by Dr. Frazer,+ this narrow belt extends
southwestward from Peters creek in Lancaster county,
*This settles one of the great Azoic questions, and Dr. Frazer should have
the credit ot predicting its settlement and furnishing the evidences, which
Mr. Keyes confirms.
fSecond Geol. Survey Pa., Report of Progress C3, 1877, pages 179 to 190-
Proc. Am. Inst. Min. Eng., Troy meeting, 1883. Proc. Am. Philos. Soc. ,
Phila., Dec. 4, 1885, page 398.
138 GEOLOGICAL SURVEY OF PENNSYLVANIA.
across the Susquehanna river and the southeast corner of
York county into Maryland. They are exposed to view in a
line of quarries in both the adjoining states about nine miles
long. * On Peters creek the black slates, 150' wide, dip 64 (S.
40 E.) under the adjoining crystalline schists. f Here the
old slate quarry of the Browns, after being operated for a
century, was bought by Bonsall & Yard and was in full play
in 1876, one-half the width of the belt being rejected as
bony, and new quarries being commenced in view of the
unprofitable depth" of the old one. Masses weighing 500 to
1,000 pounds are blasted, lifted and sawn into lengths.
The slates are not as smooth and black as the best from
Slatington & Chapman in Lehigh county. They have a
fine grain, but are liable to show incipient traces of flebby
or bubbly texture even in the finest parts of the best
varieties. In sunlight they have a purplish lusier. They
are so smooth and soft to the touch and so tough that nails
may be driven through them, and they weather well. They
are split into roof slates with BonsalFs patent knife.
Mantles, tables, tombstones, etc. are sawn and finished on
a large horizontal wheel. Much of the quarry rock is re-
jected, but part of the great refuse piles is ground into flour
for paint, cement and roof slating4
In York county the slate ridge is well-marked and well-
wooded, but neither high nor steep, with a rather uniform
outline, its summit striking southwest,! the village of Delta
*See C3, p. 182, plate 7, view of Humphrey's quarry, near Delta, York
county, and p. 184, plate 8, view of Jones <fe Co.'s quarry, in Harford county,
Md., both from photographs.
fC3, p. 179.
JThe only other quarries on this (east) side of the river, owned by Oole-
man <fe Co., were not operated in 1880. In York county the first quarry is
2i miles from the river, near Slate Hill P. O.
In J. Humphrey <fe Co.'s northern quarry the long excavation (of best
slate) points S. 55 W. The neighboring Old Revolutionary bank, full of
water, points S. 40 W. In Williams & Co.'s quarry, which is large and
deep, but nearly full of water, the hanging wall strikes S. 55 to 60 W. In
the next quarry the nearly vertical slates strike S. 40 W. (The ridge itself
at W. Bangor strikes S. 45 W.) In E. Davis' quarry a remarkable cross
dip of 87 (to S. 40 W.) demands special notice. At the west end of W-
E. Williams' quarry the slates dip 88 (X. 10 W.) with a strike of S. 80
W. ; but in the main they are vertical and strike S. 40 W. In W. C. Rob-
THE PEACH BOTTOM ROOFING-SLATES. 139
being built on its northwest slope, and most of the quarries
opened on its southeast slope ; with dips very steep, nearly
vertical, and preponderatingly to the N. W. on the quarry
side.
The whole ridge is by no means good quarry ground, as
is shown by the great number of abandoned trial shafts.
Even the long-wrought merchantable strata are capricious
and change quality both lengthwise and downward, requir-
ing very judicious mining. While the whole ridge, half a
mile wide, is of slate the paying belt (as at John Hum-
phrey & Co.'s quarry) averages only 60 or 70 feet, of which
total only 40 or 50 feet of the best slates are got from a
number of narrow benches. This excavation is about 500'
long, 50' to 70' wide, and 175' deep at its deepest place. A
gradual change of quality took place in sinking the first
40', but after that the quality remained constant to the
bottom, and no doubt would be found the same to an indefi-
nitely greater depth.
The roofing slate belt seems to belong to and be an inte-
gral part of the great "chlorite slate" formation. Such was
the impression produced upon Dr. Frazer by his official
study of it in 1877.* The marketable slate beds are inter-
leaved with others which may be properly named chlorite
schists. On the railroad at the river bank the width of the
erts' quarry the jointage planes which govern the excavation dip 45 (S. 40
to 50 W.,) but in one of the best exposures the slates dip only 20 (N. 30
W.,) making the strike S. 60 W. In J. Humphrey & Co.'s quarry the ver-
tical slates strike S. 60 W., and a jointage plane dips 30 (S. 70 W.) T. W.
Jones <fc Co.'s quarry adjoins the last In J. W. Jones <fe Co.'s quarry the
vertical slates strike regularly S. 40 W. One jointage plane system dips 30
(S. 40 W.) ; the other 80 (S. 60 W.) In Hugh E. Hughes' quarry, close
to the last, the nearly vertical slates (slightly north dip at one end and
slightly south dip at the other) strike about S. 40 U W. with several jointage
systems, one of them dipping 50 (S. 40 W.,) producing an extra amount
of waste. No valuable slates have been found further on in Maryland.
*Report C3, 1880, page 23, where he proposes the theory that the local pro-
duction of roofing slate has been eftected by the heat of a trap dyke, eighteen
miles long, which traverses the schist country of south Lancaster, passes
near the northeast end of the roofing slate belt and follows it to the river.
This theory could be more easily accepted if trap appeared along the whole
range of the slate hill in York county and Maryland ; if other belts of slate
were seen along the course of the dyke further north ; and if trap was not un-
known in the Lehigh roofing slate region and in Vermont.
140 GEOLOGICAL SUKVEY OF PENNSYLVANIA.
slate belt is about 400 feet ; but the really valuable roofing
slates recur through this distance in special belts, or layers,
each only a few yards thick. The country on each side (up
and down river) is sharply plicated ; and the slate rocks ex-
posed about 100 yards north of the slate factory (some
dipping 58, S. 55 E., others 62, S. 25 E.) "resemble the
genuine marketable slates in many features, but are
greener, more chloritic, and very much convoluted." A
close examination of the ( texture of the rocks suggests a
growing belief in "an insensible alteration of the more
chloritic hydro-mica schists into the dark purple-black
Peach Bottom slates."*
A chemical analysis of a piece of Peach Bottom roofing
slate from the Humphrey quarry, made by Mr. A. S. Mc-
Creath,f shows that it is an almost non-magnesian clay-
slate, holding 9 per cent, of ferrous oxide and blackened by
2 per cent, of carbon 4 If this be a fair representation of
the composition of the mercantile slate layers of the belt,
no theory of igne'ous alteration from an original chlorite
(magnesian) sediment can be accepted ; for the action of a
trap-dyke would add, not abstract, magnesia. We must
therefore regard the good slate-plies as separate and con-
secutive layers or beds of iron-clay, foliated by pressure ;
like the roofing slate beds of Lehigh county, but of a much
earlier age ; therefore they may possibly be identical with
the Lowest Cambrian slates of Georgia county, Vermont,
which hold the Olenellu* fauna of Walcott.
No animal fossils, no trilobites, have been noticed in these
slates ; but on the surfaces of many slabs are seen shining
ribbons, crossing each other, which seem to be fossil plants,
*C3, page 133. A specimen from J. Humphrey & Co.'s quarry shows a
fragment or unaltered mica-schist in the mass of fine slate (03, p. 190). In
W. E. Williams' quarry a seam of chlorite slate and quartz, mixed with
manganiferous iron oxide, occurs in streaks (C3, p. 188).
fReport MM, p. 370 (Copied into C3, p. 270).
jSilica, 50; alumina, 22; ferrous oxide, 9; carbon, 2; water, 3.4; potash,
3.6; magnesia, 1.5; titanic acid, 1.3; manganous oxide, 0.6; soda, 0.5; lime,
0.2; iron disulphide and sulphuric acid, each less than 0.1; and a trace of
cobalt.
See Diet, of Fossils Report P. 4. See also chapter on Cambrian fossils
further on.
THE PEACH BOTTOM ROOFING-SLATES. 141
probably sea weeds allied to Buthotrephis, but of uncer-
tain species and even genus, and lending no aid to the de-
termination of the age of the formation.* It would be
unsafe to assign it to the Lower Silurian age of the roofing
slate formation of Lehigh county on the strength of these
fossil plants. There is no good evidence in favor of the
Peach Bottom slate ridge being an isolated distant outlying
basin of Hudson river slate preserved in one of the many
folds of the Chlorite slate country ; nor is there any easy
mode of explaining the presence on the Maryland line of
such an outlier of the Lehigh valley slate belt either by
conformable deposition or by downthrow faulting. For the
present we must be content to be guided by the -lately im-
proved classification of the Cambrian slates of Canada,
Vermont, and the eastern counties of New York ; and to
consider the Peach Bottom slates as part of that early sys-
tem ; at all events, integral members of the chlorite schist
formation in which they lie.f
*Peacb Bottom slates, etc., Proc. Amer. Inst. Mining Engineers, Troy
meeting, 1883. These Peach Bottom tossils, found by Rev. I. N. Rendall,
D. D., President of Lincoln University in Chester county, at the quarries
near Delta in York county, were submitted to Prof James Hall, of Albany,
who thought them more like the Buthotrephis of the Hudson river slate
(formation No. Ill) than anything else.
Prof. J. S. Starr, of Franklin and Marshall College, exhibited some spec,
imens to the Linnean Society in Lancaster, some of which, in his opinion,
had an ill-defined resemblance to "ferns." See a report of the paper in the
"New Era," of Lancaster, May 15, 1886.
These fossil ribbons do not stand alone ; for in certain black silicious slates
near St. John occur "black, linear, flat objects that appear to be of the nature
of sea-weeds or graptolites, but not sufficiently complete to give a satisfac.
tory indication of their relationship." (G. F. Matthew on "Eozoon and
other low organisms in Laurentian rocks at St. John," in Bull. No. IX,
Nat. Hist. Soc. New Brunswick, read Oct. 7, 18900 Jt was in specimens
from a neighboring limestone of the same age that Sir William Dawson
many years ago detected fragments of Eozoon Canadense.
fThere is nothing to astonish us in the belt terminating eastward near the
river and not running on through Lancaster, Chester and Delaware counties
to the Schuylkill, more than in the Northampton and Lehigh roofing slate
belt terminating westward near the Berks county line, instead of running
continuously across the Susquehanna and Potomac rivers far into Virginia.
In both cases the mechanical agency for foliating the formation into roofing
slate operated generally, but the particular kind of clay formation capable
of being foliated was of limited extent.
142 GEOLOGICAL SURVEY OF PENNSYLVANIA.
CHAPTER XIV.
Geology of the South Mountains.
The South mountains, separating the Cumberland valley
from the lower country of York and Adams county, are the
northernmost end of the Blue ridge range of Virginia, The
highest summit rises only to 2,100' A. T. There are no
rocky peaks, and very few cliffs. The slopes are all mod-
erate and the surface everywhere rounded on a grand scale.
The long, straight, sharp, rocky crests and boldly- terraced
steep slopes of middle Pennsylvania are almost unknown
to this mass of irregularly-arranged groups of rounded
knobs and shallow valleys, for the most part bare, uncul-
tivated, or covered with a low second growth of forest re-
served for abandoned iron works of the old style.*
The whole measures upon the map ten miles in breadth
by fifty in length, upon a curve extending from the Mary-
land line to its northeastern end fifteen miles west of Har-
risburg. It ends like the human hand in four blunt fingers
and a very short, small thumb on the Cumberland valley
side. These five terminals slope with considerable beauty
down to the plain country of northern York county com-
posed of Trias rocks, and of eastern Cumberland composed
of Lower Silurian limestone, the two parts of the plain being
separated by the lower reach of Yellow Breeches creek,
which in the greater part of its course flows close at the
northern foot of the mountain mass.
Many brooks descend from the mountain through short
and rather steep ravines to Yellow Breeches creek at its
foot. At one place only in Cumberland county is the
mountain mass breached to let out the rainfall of its in-
terior surfaces. This is at Papertown, called Mt. Holly
*See description of conglomerate ridges on p. 148.
GEOLOGY OF THE SOUTH MOUNTAINS. 143
Springs, opposite Carlisle, where Mountain creek, after
flowing east in a valley twenty miles long, turns north and
issues through a fine gorge to join the Yellow Breeches.
Mountain creek heads in the corner of Adams county at
a summit-divide from which Conococheague creek flows
southwestward on the same line with Mountain creek but
in the opposite direction (that is, along a valley common
to both) to the Gettysburg-Chambersburg turnpike at
Greenwood Furnace in Franklin county, where it turns
northwest and breaks out of the mountain opposite Cham-
bersburg, exposing another rock section analogous to that
at Mt. Holly Springs.
Here, at the pike, the Mt. Holly mountain range, which
is the highest and most regular part of the South mountain
mass, virtually ends, sinking southwestward into the Cum-
berland valley.- The lower interior ridges however run on
past Greenwood and Mont Alto to sink beneath the lime-
stone cove of the Little Antietam East Branch creek, oppo-
site Waynesburg, near the Maryland line.
Thus the northwest face of the South mountain mass is
set back from the Cumberland valley, once opposite Cham-
bersburg for four miles, and again opposite Greensburg for
nearly five miles. It is this that produces the curve of the
mass upon the map. But these backsets would narrow the
mass to a point on the Maryland line were it not for corres-
ponding outsets of its eastern face in Adams county, one
at the pike near Coxtown, and another further south.
It is evident that the curve of the mass is not produced
by a curving of the ridges which compose it, but by an
eschelon arrangement of its ridges running past each other,
like the synclinal spurs of the Broad mountain in Schuyl-
kill county, or the anticlinal spurs of the Buffalo mountains
in Union and Snyder counties.
This geographical eschelon arrangement of the South
mountains is a good indication of their geological structure.
It renders it probable that the strata, whatever may be their
age, have been thrown into a series of anticlinal and syn-
clinal waves entirely analogous to those with which the
Palaeozoic country of middle Pennsylvania have made us so
144 GEOLOGICAL SURVEY OF PENNSYLVANIA.
well acquainted. It explains also the finger arrangement of
the eastern end of the mass in the Susquehanna river
country ; and leads us to suppose that the South mountain
series descends beneath Lancaster, Dauphin and Lebanon
counties, and is in some unexplained way connected with
the Highlands of Berks, Lehigh and Northampton counties,
New Jersey and New York. But it does not in the least
help us in solving the problem why the South mountain
rocks seem to be absent from that Highland country.
The South mountain rocks are mostly quartzites and
quartz slates ; those Highland rocks are mostly hornblendic
and quartz gneisses, merely veneered with quart zite patches.
If the Htironian (or Cambrian) quartzites are in such force
in the South mountains, why do they make so accidental
and superficial an element in the Highlands \ On the other
hand, why are none of the Highland gneisses, especially the
hornblendic schists, seen in the South mountains? The
underground interval is but sixty miles.
Two groups of rock compose the South mountain mass,
as shown in Dr. Frazer's cross-sections.* The northwestern
(Mt. Holly) ridge is made by several thousand feet of the
the lower quartzite and quartz conglomerate beds. The
southeastern (Adams county) ridges are made by several
thousand feet of an overlying feldspathic, micaceous and
chloride series, intersected by veins of milky quartz ; the
felsites varying in character "from a sandy and earthy slate
in which the crystals of orthoclase feldspar are very much
decomposed, indeed are almost clay,f through a jasper-
like variety to a massive and coarsely porphyritic struc-
ture in which it is suited to be used as an ornamental build-
ing stone."
These two series, or great sub- divisions, seem at some
places to graduate into each other, as if they were the
earlier and later deposits of one age. In other places (as in
the Greenwood section No. 10.) they seem distinct; the
passage from the lower quartzite series to the higher por-
*Especially well shown by his Section No. 8, Report CC, page 285.
fCompare Fontaine's "Kaolin slate" beds in the Virginia Blue Ridge
section at Balcony Falls, on James river.
GEOLOGY OF THE SOUTH MOUNTAIN. 145
phyritic (orthofelsite) series being abrupt ; with even an
apparent difference of strike in some of the outcrops along
the line of section.
The lower, or quartzlte and conglomerate slate series, is
certainly immensely thick. Its beds very generally dip
southeastward at angles varying from 20 to 60. Occasion-
ally they dip steeply the other way (northwest) implying
anticlinal and synclinal rolls ; but on the whole they are
elevated towards the Cumberland valley, as if they once
passed in the air over the Silurians of that valley, which is
a clear impossibility.
A master fault must therefore run along the northwest
foot of the mountains, along the low drift-filled valley of
Yellow Breeches creek, in which nowhere can any rock be
seen in place, but only a series of brown hematite (limonite)
iron ore deposits, some of them of great size and once ex-
tensively mined in open quarry work. The northwest face
of the mountain mass is therefore in fact the eroded basset
edge of the quartzite series dipping away from the fault.*
The thickness of the quartzite and conglomerate series
may be imagined from cross-section No. 10, laid 2^ miles
north of Greenwood, along which for five miles quartzite
beds on a prevailing southeast dip are either seen or indi-
cated, suggesting a total thickness of fourteen thousand
feet (14,000'). Other sections across the mountains towards
Mount Holly Springs (even on a rolling construction to sat-
isfy every observed abnormal dip) exhibit a certain mini-
mum thickness of 5,000', and possible maximum thickness
of 10,000' and 12,000' of the quartzite series f And if a
*Mr. Lehman's topographical map shows southeast dips all along the
summits on the northwest edge of the mountain mass ; and they are dips so
low that they cannot bespeak an overturn. They continue to the Cono-
cocheague backset; here, however, they swing round and become southwest
dips ; the quartzites sinking beneath the limestones instead of being thrust
up over them, as along the fault.
|A rather wild theory has been recently advanced by geologists studying
this range on .the Potomac at Harper's Ferry, that the quartzites of the
west side of the South mountain mass are the same as the Medina sandstone
beds of the North mountain on the west side of the Cumberland (Shen-
andoah) valley. They claim that the structure along the river makes this
evident. But if so. then the same should be the case in Pennsylvania. But
10
146 GEOLOGICAL SURVEY OF PENNSYLVANIA.
master fault really exists, as it must, along the foot of the
mountain slope, there is no knowing how much more at the
bottom is buried against the fault One single, perfectly
regular and continuous outcrop of these southeast dipping
strata was measured by Mr. Lehman, at my request, near
Mt. Holly hotel, giving a thickness of 1,200'. In Section
No. 11. near the Gettysburg-Chambersburg turnpike, there
appear to be 3,200' of quartzite and 6,400' of "schistose con-
glomerate," Dr. Frazer' s Mountain Creek Rock sub -series.*
The thickness of the overlying felspathic felsite series,
it is only necessary to compare the thickness of the Medina with the figures
in the text above to show that the theory is a mere conjecture. The Medina,
opposite Mt. Holly Springs, is only a few hundred feet thick, and increases
in thickness to 2,000' in the direction of the Allegheny mountain. See the
Perry Co. Report, F2, and the Blair, Bedford, Huntingdon (T, T2, T3) and
other reports of middle Pennsylvahia. It also increases greatly in thick-
ness towards the Delaware river; but to and beyond the Potomac it de-
creases in thickness until it is only forty (40) feet thick in E. Tennessee
west of Knoxville. Those who wish to see the grounds on which Messrs.
Geiger and Keith rest their identification of the Massannuttan (Medina
No. TV) sandstone with the quartzite of the Blue Ridge at Harper's Ferry (
will consult their sketch map and sections published in the Bulletin of the
Geol. Soc. America, Vol. 2, p. 158, where the crests are represented as
synclinals of IV, supported by shale of III, overlying the limestones of II,
unconformably resting on epidote schists and granite. The parallel syncli-
nals are represented as compressed and overthrown westward.
It has been long known that the Silurians rode over the Blue ridge and
South mountain rocks. This is evident in the case of the Highlands ot
Northampton county ; evident in Lancaster and York counties ; evident in
the James river country ; therefore there is no objection whatever to lime-
stone synclinals capped by shale and sandstone (III, IV) on the Blue
Ridge. Mr. Keyes' section (Bull. Geol. Soc. Amer., Vol. 2, page 320) shows
the Chazy and Trenton with tneir characteristic fossils on theeastsideofthe
range (between Cotocton mountain and Sugar Loaf, in Maryland). Cotocton
mountain sandstone may possibly be Hellarn (Chiques) quartzite No. I, and
Sugar Loaf certainly is ; but nothing can suffice to identify the Medina with
the vast quartzite masses of our Mt. Holly range.
But the greatest obstacle to finding the Medina in or on the range is the
vast thickness of the limestones of II and slates of III on which the Medina
lies. Any outlying crest of Medina would be supported by at least 5,000 feet
of these limestones and slates, and if preserved by erosion in the body of the
Blue Ridge range of Maryland and Pennsylvania, could only be so pre-
served at an elevation of 5, 000 feet above tide. This topographical necessity
js fatal to the hypothesis, even if profound downthrow faults be substituted
conjecturally for synclinals. It is remarkable that Messrs. Geiger and Keyes
do not explain the absence of the limestone from their map.
*CC, p. 295, and Section No. II.
GEOLOGY OF THE SOUTH MOUNTAIN. 147
along the Mt. Holly cross-section, No. 8, exceeds 6,000', as
shown in the broad synclinal with opposite dips of from
30 to 50 at the southern end of the section. The highest
b^ds left in the center of this basin are green crystalline
schists and orthofelsites. How many still higher beds have
been removed by erosion cannot be known. In Section No.
11, near the G. and C. turnpike, a small synclinal holds
700' or 800' of hydro-mica slates, and over these a continu-
ous monoclinal exhibition of orthofelsite a mile and a half
long, ''representing (if there be no unknown reverse dips)
nearly 5,000 feet of strata" (CC, p. 295).
The Mountain Creek Rock sub-division of the Lower
series is characterized by scattered pebbles and by occa-
sional solid beds of conglomerate. Dr. Frazer gives it various
names descriptive of its varieties: "Schist conglome-
rate," "chlorite schist conglomerate," "quartz conglomerate
schist." "green schist with quartz pebbles," "hydro-mica
schist with pebbles" (some of them of transparent quartz,
others of amethyst-colored quartz), these last two varieties
of conglomerate marking a transition to the Upper series.
It is evident that the great Lower series, if indeed it be sep-
arable from the Upper, has a lowest set of beds which are
almost wholly of metamorphosed sand, quartzite. Then
higher sets of clay, sand and pebble beds, metamorphosed
into quartzoze slates, shales, schists and pebble rock.
The still higher and more or less magnesian slates,
hard shales, crystalline schists with scattered pebbles,
conglomerate beds, and porpyhritic beds, make an indefi-
nite but recognizable Upper system, in which also occur true
quartzite beds, like-those at the bottom of the Lower series.
Occasional fragments of diorite trap appear on the surface,
which may indicate interbedded volcanic rocks, or possibly
very small dikes. The whole may have been capped by
the Hellam (Chiques rock) quartzite, fragments of which
are so abundant on the lower southeast slope of the South
mountain mass.
It is hard to avoid the inference that our South mountain
rocks represent the Huronian section of Murray and Logan.
It is impossible not to compare them also with the great
148 GEOLOGICAL SURVEY OF PENNSYLVANIA.
quartzite masses, the roofing slates, etc., of Wolcott's
upper, middle and lower Cambrian system.*
The conglomerate beds sometimes make bold features in
the scene. North of the pike at Greenwood a narrow valley,
one or two hundred feet in depth, is shut in by a straight
sharp-crested little ridge produced by a few beds of coarse
conglomerate, in all not more than fifty feet thick, whose
fragments are piled along the narrow top, strew the steep
northwestern basset slope and choke up two wild little
ravine gaps through which the drainage of the back-valley
relieves itself. One is appropriately called Dark Hollow.
The dip of the conglomerate beds, and of all the strata on
both sides of the ridge, is uniformly about 45 S. E. On
the S. E. slope of the ridge, and therefore about a hundred
feet geologically above the conglomerates, is the outcrop of
a five or six-foot bed of iron ore, tunneled to and mined by
Thad. Stevens for the use of his Caledonia furnace at the
pike. I was not able to trace the conglomerate to the pike;
but the ridge is represented topographically that far ; and
what seems to be the same iron ore bed, or one at about the
same horizon, was opened and mined a little at the foot of
the steep S. E. dipping rocky cliffs on the north bank of
the creek, the turnpike following the south bank.f
Another conglomerate several thousand feet higher in
the series than the last, and composed of a few rather
massive layers, only 20 or 80 feet thick in all, makes a very
curious triangular plate leaning against the face of the hill
*But where have we the Huronian and Cambrian limestone intercala-
tions? Possibly in the Pine Grove Furnace limestone on Mountain creek;
which, however, Pennsylvania geologists have always referred to the great
limestone formation of the Cumberland valley; considering it a synclinal
outlier, like the Saucon, Oley and Downingtown limestone outliers in
Northampton, Berks and Chester counties. If the Pine Grove limestone be-
longs to the South mountain mass, it is certainly a very extraordinar\- fact
that it does not crop out anywhere else in the South mountains except just
there along Mountain creek ; and that it is there accompanied with the same
decomposed damourite limeslates and brown hematite iron ores which
range with the Cumberland valley limestones from the Delaware to the
Potomac and far into the Southern States.
f These were some of the local facts which persuaded me that the mount-
ain backset at the pike and creek had been made by a great cross-fault, with
a throw of four miles.
GEOLOGY OF THE SOUTH MOUNTAIN. 149
on the northwest side of the Conococheague, four miles
north of the turnpike. The base of the triangle is in the
bed of the creek ; its apex makes a little platform project-
ing from the side of the wagon road, here more than a
hundred feet above the creek. The outcrop slopes slanting
both ways down to the creek, and reappears again in low
bluffs at the mouth of a branch further on, whence it can
be traced a mile or two further northeast, ascending to the
higher land.*
These two instances prove the general fact that these con-
glomerate beds are not mere local bunchings of gravel, but
are widely extended gravel deposits at fixed horizons in the
series, and may therefore be used as key-rocks for working
out the geology and perhaps for breaking up the series
into sub-divisions which may at some future time receive
distinctive names. But they lend no help to the notion
that they are of Medina age, because they areinterstratified
with a great thickness of other beds.
A conglomerate of coarse character and some thickness
makes a ridge with a bold south-facing cliff end in the
ravine issuing at Mont Alto. The dips here are vertical,
and the place of the beds in the series is undetermined.
The locality is ten miles south of the pike at Greenwood ;
a north and south road connects the two, and along this
road the ridge is faced with jaspery grey and purple slates,
quarried for road metal, f
*Standing on the apex of the triangle and looking eastward across the
valley of the Conococheague, one sees opposite, about half a mile away and
at the same height, the apex of a similar triangular outcrop of the same con-
glomerate* beds dipping northwest about 20. The creek here flows in a
shallow synclinal fold, as represented on Dr. Frazer's Section No. 11. The
exhibition ol erosion is unusual and very interesting. The conglomerate
soon turns over to a southeast dip, sinks into the broad highland of S. E.
dipping conglomerate schists at least 5,000' thick, past another small syn-
clinal roll, to the 70 S. E. dipping green hydro-mica schists and micaceous
slates which introduce the orthofelsite country from Newman's (on the
pike) to Cashtown at the northwest edge of the Triasic plain.
These features of topography the straight sharp conglomerate ridges
and gaps, the triangular outcrops and iron mines, are exhibited on my map
of the Caledonia Furnace lands (surveyed by me in 1873) in the Atlas ac-
companying this Report
fSuch purplish red slates are an uncommon element in the South mount-
ain mass, but they have been occasionally observed. There is no general ex-
150 GEOLOGICAL SURVEY OF PENNSYLVANIA.
The number of these conglomerate beds may be exagge-
rated on account of the rolling (anticlinal and synclinal)
structure of the mountain mass as a whole. It is evident
that the rolls must be more numerous than the outcrops
show, the surface being smoothly eroded and covered with
sand. The whole mass descends from northwest to south-
east, but it descends in a series of rolls, some of which are
very distinct, but most of them are mere crimples. It has
just been said that the Conococheague north of the pike
flows in a synclinal (see foot-note on last page).
Section 8 shows that Mountain creek, at Pinegrove Fur-
nace, flows in this same synclinal, of the same shape and
size ; and that the rocks turn over in the same way south-
eastward. Several other small synclinals occur on that sec-
tion (if the surface dips be properly correlated), one of
them tightly compressed and thrown over to the west.
There is a rather grand synclinal at the eastern end of that
section.
Section 9 was made along the Gettysburg-Shippensburg
road over the highest part of the mountain. It starts at the
summit of the Mt. Holly quartzite range, 2,100' above tide,
and runs S. E. nearly five miles to the Conewago creek 4
miles from Arendtsville. A mile from the summit, ap-
proaching Beamer's mill on Mountain creek, the following
opposite-dipping outcrops of quartzite are encountered in
rapid succession : S. 45 E., 60 (two) ; N. W. ? ; S. 45 E..
50; N. 40 W. 40; S. 35 E. 70; N. 35 W. 55, 70
(two). How many more such crimples are concealed under
the sand which covers the mountain is not known* Then
follows a gap of 6,575', the surface being strewn with frag-
ments of conglomerate schist and quartzite, but nothing ex-
posed. In the last half mile the schist becomes more and
more composed of small quartz fragments until the rock
turns into a nearly perfect quartzite. Then appear quartzose
conglomerate schist dipping S. 35 E., 45, 50 (two out-
crops) ; N. 60 W. 20. A mile further orthofelsite and
hibition of them as in the Cambrian country of Vermont and eastern New
York. Pink quartzites occupy the west end of Section No. 11, on the higli
ridge 1| miles west of the Conococheague and 2| miles N. 20 E. of Cale-
donia furnace. (Report CC, p. 293. )
GEOLOGY OF THE SOUTH MOUNTAIN. 151
schist are exposed, dipping S. 15 E. 85 ; S. 40 E. 55.
These two dips are evidently on the crest of a sharp anti-
clinal roll of unknown quantity.
The relationship ol the South mountain rocks to the rest
of the Azoic rocks of the state, to the Highlands, to the Phil-
adelphia belt, to the York and Lancaster county gneisses
and hydromica slates, or phyllites, is certainly obscure.
But their relationship to the great Huronian formations of
Canada and the northwestern states is also an interestingly
doubtful problem, for the discussion of which a description
of the Huronian in its typical locality is necessary and will
be given in the next chapter for the use of Pennsylvania
geologists. How the Huronian and Cambrian are related
I do not pretend to discuss.
152 GEOLOGICAL SURVEY OF PENNSYLVANIA.
CHAPTER XV.
The Huronian system.
The Huronian system is a vast series of beds of gravel
sand and mud (altered to quartzites, greywackes* and
slates), with some beds of limestone and chert, and some
beds of volcanic ashes (or lava ? greenstone trap), the whole
being traversed by trap dykes, exhibited on the northern
shore of Lake Huron in upper Canada.
Logan's section of 1863 f gives the relative proportions of
the kinds of rock, thus : Quartzites. 10,820' ; Graywackes
(slate conglomerates) 4,280'; Chlorite slates, epidote slates,
and trap-like beds, 2,000'; Limestone and schist beds, 900'.
Total of undulating strata visible along the north shore of
Lake Huron, 18,000'.
But the proportion of Quartzites is even greater than this
and amounts to at least two-thirds of the whole ; one-sixth
consists of Graywackes (slate conglomerates) ; one-ninth of
Chlorite, epidote and trap beds ; one-eighteenth of Lime-
stone and schist beds. In other words, 12 : 3 : 2 : 14
*This term, r/raywacke, greywacke, grauwacke, has almost disappeared
from geological literature, but is common in the older books. Lyell ex-
plains it in his Manual of Elementary Geology ( N. Y. reprint 1853, p. 350) as
a German miner's name for brecciated sand rocks of the Silurian system,
composed of small fragments of quartz, flintslate (Lydian stone) and clay-
slate in a clay cement. Similar grits are found in Devonian, Carboniferous,
Cretaceous and Eocene ages ; and they are common among Huronian rocks,
where the cement is more siliceous and the feldspar fragments are in an al-
tered condition (Irving). They are the Huronian "conglomerates" of the
later literature.
fGeol. Canada, 1863, p. 55, Atlas Plate 3. This section has recently been
verified by Irving ; U. S. Geol. Sur. 5, Report 4, 1885, p. 188.
JMurray described the series in his report to Logan (G. S. Can., 1847-8, p.
189) as "a set of regularly stratified .... quartz rocks (or altered sand-
stones), conglomerates, slates and limestones, interstratified with beds of
greenstone." Under the term slates he included "thinly-laminated, dark-
green, blackish and reddish rocks, some ... very chloritic (magnesian)
and some containing epidote." Hunt makes the smaller items of the list
THE HURONIAN SYSTEM. 153
Thin sections under the microscope show the quartzites,
graywackes and slates to he sediments hardened into rock
chiefly by the infiltration of siliceous waters, the silica
being deposited so slowly between the grains as to crystal-
lize around them, so that the shape of the grain remains
visible in the interior of the enveloping crystal of quartz.*
The chloritic and epidotic slates which make up so small
a part of the column have been made by Dr. Hunt the
basis of an immense generalization extending over Europe
and America. From the typical locality of these slates,
just east of Thessalon Point, Irving' s specimens under
the microscope showed themselves to be "merely eruptive
diabasic greenstones in various degrees of alteration." The
false idea that the Huronian series on Lake Huron is char-
acteristically chloritic has been partly generated by the oc-
currence of greenish chloritic graywackes in the slate con-
glomerates, f
The alteration of the rocks on Lake Huron is not dif-
ferent from, but only more universal than, that of ac-
knowledged sedimentary and fossiliferous sandrocks etc.
The basic traps are augitic in various stages of alteration,
too important when he quotes Murray's rocks as "a great series of chloritic
slates and conglomerates, with interstratified greenstones, quartzites and
limestones." (Azoic Rocks, Report N, Geol Sur. of Perm., p. 70.) This puts
a false face upon the whole formation, and raises great difficulties in the way
of identifying it in other regions. Irving adds that a large proportion ol the
so-called slate conglomerates is quartzite, the balance being gray wacke slates
and graywacke conglomerates, which he describes in extenso in subsequent
pages of his report to the U. S. Geol. Survey, 5th Rept., 1885. Logan in-
cludes various greenstone trap beds in his measured groups.
*Irving, 1885, p. 188. Also his chapter on enlargements of mineral frag-
ments in certain detrital rocks, in same report, pp. 218, to 242 with figures,
plates 30, 31, and wood-cuts on pp. 238, 239, showing how the planes of crys-
tallization in the embedded fragment are continued outwardly through the
encrusting quartz crystal envelope. He has pursued bis investigation with
tine results through quartzites of Potsdam and Medina age, and furnished a
sufficient explanation of the process by which the loose sand and mud de-
posits have been more or less completely converted into hard, brittle sand-
rocks and slates.
(Irving's foot-note to page 188. Irving, Van Hise and Merriam made
their study of the coast line from Sault St Marie eastward to Serpent river
bay, with Logan's map, in 1884, and far enough inland to get the whole of
Logan's series, occupying the area between St. Mary's and Blind rivers.
154 GEOLOGICAL SURVEY OF PENNSYLVANIA.
hornblende being a secondary product. The bedded trap
does not differ from the dyke trap.
The strata are so little inclined, so gently folded, so im-
perfectly metamorphosed, and so different in looks from
crystalline schists, that the total absence of fossils argues
an age without life; seeing that fossils are constantly
found in rocks no more altered than these.*
The absence of red hematite ore beds from the section of
typical Huronian strata is remarkable. In spite of this
fact, however, it is generally agreed that the great series of
highly-folded fragmental slates and quartzites, chert schists,
magnetite schists, iron ore beds, limestones, dolomites,
clayslates, micaslates and greenstone of the Marquette and
Menomonee region south of Lake Superior is merely the
geographical extension of those on the north shore of Lake
Huron. f The greenish schists at the base of the Marquette
series may perhaps belong to the underlying system of
Laurentian gneiss. :(: Beds of strange-looking rocks may be
explained by secondary alteration of basic eruptives, e. g.,
hornblende schists and actinolite schists, the graduation of
which into greenstone has been both affirmed and denied
and given rise to the two opposite views, that either both
nre sedimentary, or both eruptive. But setting aside these
doubtful elements of the whole section, its main features
are those of the typical quartzite Huronian.
*Irving, p. 189. A curious and very different explanation of the absence
of fossils from Huronian rocks has been offered by Dr. Morris in the pro-
ceedings of the Acad. Nat. ScL, Phila., April 7, 1885. Alter drawing atten-
tion to the fact that the oldest known animals have defensive armour, but
no offensive weapons, and suggesting that they were descendants of un-
armoured ancestors, in whom the appearance of predatory foes had devel-
oped modes of self-defense, i. e., the secretion of shell structure, which
compelled them to exchange a free swimming life for rest at the sea bottom,
j ust as afterwards the secretion of the internal skeleton was acquired, he
assumes that the unarmoured ancestry could leave no traces of their exist-
ence, i. e., no fossils in the Huronian. But no one will dispute that life
commenced at some date or other. Why not then in post Huronian times?
. fSee the Reports of Brooks, Rominger and others, who differ widely in
their arrangement of the series.
Jlrving, p. 190.
Irving, pp. 190, 191. Some of the greenstones are evidently contempo-
raneous lava beds now regularly interstratified ; others are as evidently
later lava dykes. As for the Marquette jaspery iron ores, the earlier geol-
THE HURONIAN SYSTEM, 155
Sir W. E. Logan's description of the Huronian section
from the survey of Mr. Murray in 1847, '48 and '49, is as
follows :*
The group consists of siliceous slates and slate con-
glomerates, holding pebbles of syenite ; sandstones some-
times showing ripple-marks, some of the sandstones pale-
red green ; and quartzose conglomerates, in which blood-
red jasper pebbles become largely mingled with those of
white quartzite, and in great mountain masses predominate
over them ; the series intersected and interstratified with
greenstone trap, and computed to be about 10,000 feet
thick ; a copper-bearing formation, etc. To this must be
added from other descriptions of it its distinctive features :
Chloritic schists, crystalline limestones andsulpher-copper
ores ; its sandstones all in the condition of quartzize, and a
total absence of fossil forms.
ogists saw in them eruptive outbursts with a flow-lamination ; a view lately
revived by Whitney and Wadsworth. Most subsequent geologists have
looked upon them as iron-silica sediments. They differ from all known
lavas in being so nearly a pure silica ; and it seems impossible to imagine a
molten flow of free silica in presence of free oxide of iron. If they be sedi-
iments, the question arises whether they were chemical or mechanical sed-
iments. The latter view finds its support in the loose magnetic sand deposits
on the shore of the lower St. Lawrence, of the Pacific coast and elsewhere,
and in the constitution of the magnetite ore beds of New Jersey. (See also
J alien's "Genesis, etc., in Eng. and Min. Jour. N. Y., Feb. 2, 1884.) Irving
c-annot accept the eruptive origin of the Marquette jaspery ores because they
graduate from pure sediments into highly contorted and confused masses ;
but chiefly because magnetite sediments have been discovered in the
Huronian quartzite series in Wisconsin and along the northwest coast of
Lake Superior. Here the Animikie series (Huronian) are quite undis-
turbed and undoubtedly sedimentary. He agrees with N. H. Winchell
that some of the Animikie magnetic ores occur in eruptive gabbro lavas,
in isolated masses, and also disseminated ; but they bear no resemblance to
the Huronian jaspery ores. (See 10th An. Rt G. Sur. Minnesota, pp. 88, 83.)
The silica of much of the jasper ore is purely crystalline quartz; but much
of it is amorphous (chalcedony). Many of the great belts of ore-bearing
rocks of the Menomonee seem mainly composed of chalcedony, which
Irving thinks is an original formation, but Wadsworth eruptive. But the oc-
currence of huge angular jaspery and chalcedonic fragments in the con-
glomerate beds overlying the Vermillion Lake iron belt shows that the
jasper and chalcedony beds existed in that form before the deposits of the
quartzites overlying them. They may represent the "chert beds" in Logan's
original section. Irving, p. 193. )
*Proc. Am. Ass. Adv. Science, Aug., 1857.
150 GEOLOGICAL SURVEY OF PENNSYLVANIA.
Another description of it* is more precise and elab-
orate. By this it would appear that the beds first depos-
ited were white sand, 500 feet in thickness ; then, mag-
nesian mud, 2,000 feet; then, white sand, 1,000'; gravel,
sand and mud, 1,280'; limestone, 300'; gravel, sand and
mud, 3,000'; red sand and gravel, 2.300'; red jasper gravel,
2,150'; white sand, 2,970'; limestone, sand and sinter, 400';
white sand, 1,500; limestone, 200', and over all, white
sand again, 400', the whole amounting to 18,000 ; but this
includes a great thickness of interst ratified greenstone trap.
What first attracts attention is the vast quantity of stuff
deposited in this ancient Huronian lake or sea or arm of the
ocean, whatever it was ; 18,000 feet in all. a thickness of
strata equal to three miles of vertical depth. Secondly, the
great preponderance in quantity of sand and gravel, 15,000
feet in all, over the quantity of finer muds, 2,000 feet, of
limestone, 900 feet ; indicating the force of the rivers which
brought the materials to the shore. Thirdly, the alterna-
tion of coarse and fine deposits, representing, as is sup-
posed, alternate risings and fallings of the sea level, and
consequent retreatings and advancings of the shore line ;
for gravel is reckoned a shore deposit, sand and mud an off-
shore deposit, and limestone a deep-sea deposit. But we
have still much to learn on this subject. In any case, such
alternations bear witness to repeated and considerable
changes in geography during the deposit of these 18, 000 feet
of strata ; and it behooves us to get some probable explan-
ation of the cause of such changes, and some conception,
however imperfect, of their geographical extent,
It is notable that at least one-fourth of the whole 18,-
000 feet of strata is reputed to be made up of volcanic
materials. If so, it is plain to see that the land and sea and
air were greatly disturbed -by fiery phenomena on a grand
scale, producing frequent changes in the sea bottom, coast
line and drainage system of that district.
Probably then other districts were subjected to similar
vicissitudes of land and sea, each district attending to its
*Crystalline Rocks of the Northwest, N. H. Winchell, Address before
Section E, Amer. Ass. Ad. Sci., Sept. 4, 1884.
THE HURONIAN SYSTEM. 157
own local and peculiar geological business, of a kind per-
haps very different from that of the Huronian rock section
cited above, and yet contemporaneous.
It would also follow that there must have been a uni-
versal, irregular, changing floor upon which, in many parts
of the earth's surface at the same time, sediments local in
their origin, local in their destination, and special in their
nature were dumped into standing water, in variable quan-
tities, at variable rates, under varying conditions and in a
variable order. We know of no such floor if it be not rep-
resented at the present surface here and there by the areas
of hornblendic granite and gneiss rocks ; whether these be
considered as the cooled and crystallized original crust-
matter of the globe, or whether they be looked upon as most
ancient sediments metamorphosed or recrystallized. Now,
any sediments deposited upon the floor anywhere would
necessarily lie unconformably upon the older gneisses; and
therefore the first of the three questions proposed above
was there a historic break between the end of the Laurentian
age and the beginning of the Huronian age ? would seem
to be answered in the affirmative. But the answer is
purely theoretical and does not help us a whit, unless we
can convict the lowest bed which shows itself in the Lake
Huron country of being really and truly the first and
bottom bed deposited upon that part of the granite floor.
Of this fact there is up to the present time no proof ; nor is
it known with an approach to certainty how the Huronian
strata lie upon the Laurentian rocks ; nor whether the so-
called upper Laurentian series, with its limestones, be not
a continuation downwards, or even sideways, of the Huron-
ian strata.
In the midst of such uncertainties the term Huronian
must be used simply as a proper and private name for a
series of rocks exposed along that part of the northern
boundary of the United States. Should a similar series ap-
pear in some other region and be called Huronian on ac-
count of the resemblance, the name would have no time-
nalue whatever ; unless we should imagine that in a so-
called Huronian age the whole surface of the planet was
158 GEOLOGICAL SURVEY OF PENNSYLVANIA.
stuccoed with a certain formation ; and received successive
coats of other kinds of rock in after ages. And in fact this
is a popular view, but absolutely false. For, ocean sedi-
ments depend for their character upon the kind of country
rocks through which the rivers flow which bring the sedi-
ments down to the sea coasts. It is impossible for the sed-
iments of two water basins to be of the same character
unless the geology of them both should be the same ; and
if two such similarly-situated water basins are filled suc-
cessively, one after the other, then the similarity of their
deposits cannot make them of the same age.
In like manner the most dissimilar series of formations
are known to be of the same age ; because brought by dif-
ferent rivers or groups of rivers from back countries of
quite different characters. What is happening to-day has
happened in all ages. Nothing could be more unlike than
the deposits now forming along the various ocean shores,
and in different lakes and inland seas ; yet they are all of
one age. Even the deposits making in one and the same
basin radically differ ; as, for example, along the northern
and the southern sides of Lake Ontario ; and along the
eastern and western sides of Lake Champlain. It would
therefore seem a useless task to seek for the Huronian
rocks far from their native range. And in point of fact the
task whenever attempted has been unsuccessful. If Huron-
ian strata existed elsewhere, it would be around the Lau-
rentian mass of the Adirondack mountains in northern
New York. But they are not to be found there. To say
that they once covered the granite and the gneiss of that
country, but have been removed, would be to beg the
question. It is not to be imagined that 18,000 or even
10,000 feet of such rocks could be removed without leaving
a trace behind. The small exhibition of specular iron ore
and slate in St. Lawrence county cannot be accepted as an
equivalent of the Huronian system merely because it
underlies the Potsdam sandstone and suggests the Mar-
quette ores; especially in the 'face of the fact that Mar-
quette iron ores are not represented in the section along
Lake Huron ; nor do they immediately underlie the Pots-
dam sandstone on Lake Superior.
THE HURONIAN SYSTEM. lf)9
Another region where we should expect the Huronian
series to appear is the region of the Highlands in southern
New York, northern New Jersey and eastern Pennsyl-
vania ; but they are nowhere to be seen in their supposed
intermediate position between the Old gneiss rocks arid the
overlying fossiliferous sediments.
On the eastern side of the extension of this Highland
range through Massachusetts and Vermont into Canada
there is a narrow belt of so-called Huronian rocks, running
along through Halifax, Marlboro', Townsend, Andover,
Plymouth and Stockbridge counties in Vermont, gradually
widening towards the Canada line and appearing on both
sides of the central belt of gneiss.* Another belt further
east commences in Norwich county on the west bank of the
Connecticut river, widening and crossing to the eastern side
of the river before reaching Canada. But there is nothing
to show that these formations have anything to do in ori-
gin, time or character with those of Lake Huron. "The
name Huronian is used," says Prof. Hitchcock, "-as a mat-
ter of convenience to designate all the various schists of
chlorite and argillite aspect overlying the gneisses, and in-
ferior to the Cambrian, so far as known." ''In southern
New Hampshire the argillite, quartzose and micaceous di-
visions predominate nearly to the exclusion of thechloritic
schists, which, with the characteristic dolomite, is seen in
Raymond and Derry. Steatite occurs in it at Francestown
in the ferruginous slates, and in the mica schists of Derry."
The Green mountain Highland crystalline rock range of
Vermont is extended into Canada under the name of the
Mountains of Notre Dame for 150 miles, being 30 miles
wide at the Vermont line, 12 where the St. Frances river
breaks through it, and 12 on the river Chaudiere ; rising to
heights of 3,000 feet above tide, and sinking south of the
Isle d' Orleans beneath the sedimentary strata, to rise again
250 miles further on as the Shickshonk mountain range, 60
miles long and 3,000 feet high, ending eastward at the river
*See description of XIII sections crossing N. H. and Vermont, by Prof. C.
H. Hitchcock, Concord, N. H., 1884, and on page 14.
1'60 GEOLOGICAL SURVEY OF PENNSYLVANIA.
St. Anne in the river Gaspe peninsula.* The range is de-
scribed asf made up of clayslates, micaceous, talcose and
chloritic schists (often with much epidote); interstratified
iron-bearing magnesiau limestones, soapstones and serpen-
tines ; quartzites ; and massive diallagic, hornblendic, py-
roxenic and feldspathic rocks; with beds of magnetic, specu-
lar, titanic and chromic iron ore, beds of sulphuret of cop-
per and native gold.
Now, are these exceedingly various kinds of azoic rocks
arranged in any constant order of superposition to one an-
other, and does the order as seen in Canada correspond to
their order in Vermont, in New York, in New Jersey, in
Pennsylvania? Such a fact, so essential to the proper
writing of a history of events in the Azoic age, has never
been made out by any geologist. The catalogue of rocks
mentioned above includes all the principal kinds of pure
and mixed sands, pure and mixed clays, pure and mixed
lime-mads, argillaceous, siliceous, calcareous, magnesian,
sulphurous, ferruginous, cupriferous, which might be ex-
pected from the drainage of any primeval region of the
fundamental earth-crust, anywhere, at any time, in any
water basin, large or small ; subsequently more or less al-
tered by the influence of heat and pressure through an in-
definitely protracted length of time. For, it must be kept
in mind, that these sediments lay originally miles beneath
their present level as respects the present sea level, and
were covered with*a world of later sedimentary strata,
fragments of which remain to tell the tale ; for example, a
piece of the Mohawk formation on the top of Mt. Eolus in
Vermont, and some Niagara and Helderburg strata in Bar-
nardston on the Connecticut river. No structural geologist
can persuade himself that the Catskill formation stopped at
the Hudson river, or that the Coal measures of the Schuylkill
and Lehigh were not originally continuous with those of
Rhode Island. All the formations of middle Pennsylvania
were therefore at one time piled upon New England, which
involves the statement just made that the Green mountain
*See Report E, page 83.
fldem, p. 85.
THE HUEONIAN SYSTEM. 161
rocks were miles below their present surface, and subject to
a constant temperature twice as great as that of boiling
water, and a constant pressure of 40,000 pounds to the
square inch, a pressure growing lighter of course as the
superincumbent mass was gradually removed in course of
time ; leaving them in their present crystalline condition ;
a condition therefore not to be explained wholly by refer-
ence to their creation in any particular age, Huronian or
otherwise.*
The opportunity for the removal of the superimposed
strata, and for the erosion of a part of the crystalline rocks
themselves, was afforded by an upthrust along the whole
range from Reading in Pennsylvania to the shore of the
St. Lawrence, irregular in its details, of unknown cause
and of unknown date ; producing a long and narrow arch,
the sides of which were so compressed as to complicate the
crown of the arch with minor folds, as seen in the Durham
hills upon the Delaware, in the Highlands of New Jersey
and New York upon the Hudson, and the sections made
across Vermont. The body of the arch is underground ; its
crown, appearing at the present surface, consists of the so-
called Older Gneiss. On its two flanks should appear the
upper members of the crystalline series. But in point of
fact, along its northwestern side much later strata lean
against the arch ; and the various crystalline schists and
slates, micaceous and magnesian, the serpentines and
soapstones, the talcs and chlorites, the chrome and gold and
copper-bearing rocks, which are called the upper members
of the series, seem to be confined to its southeastern flank
and are spread abroad through the regions which lie in that
direction. With all our efforts we cannot comprehend it ;
for the true nature of that first great movement has been
almost entirely concealed from our inspection, and masked
by the consequences of other more or less similar subse-
quent derangements of the ancient state of things along
the Atlantic seaboard. The confusion and obscurity which
*lt remains to be explained however why the lowest Palaeozoic strata are
not more and more generally crystalline, although subjected to part of the
same load.
11
162 GEOLOGICAL SURVEY OF PENNSYLVANIA.
characterize the literature of the geology of all New Eng-
land, the several states of which have been studied by emi-
nent geologists for half a century, the conflict kept up
between the advocates of the sedimentary stratification and
the advocates of the volcanic or plutonic outflow of the
granitic and gneissic rocks, and the irreconcilable differ-
ences of arrangement of its rock masses and rock belts as
well- characterized formations in sequence of time, prove
how little is yet known of the geological history of the
Azoic age or ages in America.
It cannot be wondered at then that the difficulties en-
countered in New England should be felt with equal force
in studying the azoic areas of New Jersey and Pennsyl-
vania, and that the geologists of these states should refuse
to use the names applied to New England and Canadian
rocks until their validity be better shown. The application
of local names to distant regions under such circum-
stances can only be a delusion and a snare. In the case of
unaltered well-stratified and fossil-bearing deposits a name
can safely be allowed to follow a geographical outcrop to
any distance ; but even then, as will be shown further on,
the difference of character and thickness which one and the
same continuous formation exhibits when traced for hun-
dreds of miles makes the use of the name first given to it
in one locality of delicate and doubtful propriety else-
where, especially when the name is intended to indicate the
special geological age in which the sediment was deposited.
The supposed English equivalents.
In 1879, Hicks read his paper on a new group of Pre-
Cambrian Rocks (the Arvonian) in Pembrokeshire, before
the Feb. 5 meeting of the Geological Society of London.*
This paper gave rise to a controversy which has thus far
shown no abatement ; but on the contrary has drawn into
its vortex most of the geologists on both sides of the At-
lantic ; so that the peninsular of St. Davids has been the
typical battle-ground between those who multiply pre-Cam-
* Q. J. G. S. XXXV, ii, p. 285-294, with a little map.
THE SUPPOSED ENGLISH EQUIVALENTS. 163
brian formations and those who refuse to classify them on
account of their obscurity.
The Arvon/an of Hicks are supposed to underlie the
Pebidian, which underlie the Cambrian. They are sup-
posed to rest upon the Dimetian (Laurentian) gneiss ;
and therefore to be the equivalents of the Huronian in
America, and of the HaUeflinta series in Scandinavia ; sed-
imentary beds ; the rock being a "micro- crystalline mass of
quartz grains with some intersticial light-gray substance
having but little action on polarized light ; but the chief
peculiarity consists in the manner in which the quartz is
separated away into nests, so as to give that curious por-
phyritic appearance ; the grains so compressed to-
gether (and yet distinctly fragmentary) that all other
material is removed and nests of pure quartz grains only
are seen having a very crystalline appearance ;
the darker material is brought together and made to fold
round the nests, so that a banded or imperfect flow-
structure is given to the rock .... as if an incipient
gneiss was being formed," etc. Fragments of these halle-
flinta beds are said to be found in the Pebidian measures,
which are therefore accounted of later age and seem to rest
against the Arvonian everywhere unconformably.* The
different characters of the three formations are thus stated :
Pebidian ; (a) micaceous, talcose and chloritic schists,
with slaty and massive green bands containing epidote,
serpentine, etc.;f (b) tuffs, indurated ashy shales, breccias,
silvery schists, porcellanites, conglomerates and agglom-
erates.
Arvonian; breccias, halleflintas and quartz-felsites4
Dimetian; quartzose rocks, granitoid gneiss, and com-
pact granitoid rocks with bands of crystalline limestone
(LaurentianT).
Dr. Hicks read at the same meeting another paper on the
pre Cambrian (Dimetian, Arvonian and Pebidian) rocks
*See Hicks' previous paper in the Q. J. G. S. XXXIV, p. 153.
f These correspond somewhat to our South Valley Hill rocks.
t These are supposed by Hunt (T. S.) to correspond to our South mount-
ain rocks, in Adams county, soutn of the Chambersburg-Gettysburg turn-
pike. See his Report of Progress E.
164 GEOLOGICAL SURVEY OF PENNSYLVANIA.
in Caernarvonshire and Anglesea as a sequel to his paper
of December, 1877, Q. J. G. S., XXXIV, p. 147) in which he
describes his re-examination of the district in company of
Prof. Torrell of Stockholm, Mr. Tawney and Prof. Hughes
of Cambridge, and Dr. T. Sterry Hunt of Montreal, and the
evidences they obtained of the reality of the distinction and
order of time ascribed to the three great formations. The
paper contains a map of the country from Holyhead to Port-
madoc, and Prof. T. G. Bonney's description of micro-
scopic rock sections.*
Prof. Bonney, however, read at the same meeting a paper
on the Quartz-felsites of Caernarvonshire, in which he de-
cidedly rejected on microscopic grounds the views of Dr.
Hicks and Prof. Hughes about their sedimentary and met-
amorphic origin, and affirmed that they have the character-
istic features of fluid igneous rocks (rhyolites], lavas of
Cambrian age ; of which he gives six remarkable pictures
(pi. 13, p. 320) showing the internal flow-structure, mag-
nified 50 diameters ; also a cross-section (with one great
anticlinal and one great synclinal) of (5) Pebidian rocks ;
purple slates resting on (4) green slaty grits; on (3) grits
and conglomerate beds ; on (2) lower conglomerates inter-
banded with green slates ; on (1) green slates not less than
3,000' thick, cut off from the (supposed older) quartz-felsite
group by a greenstone dyke.
* Q. J. G. S., XXXV, p. 295-308.
NO. I. CHIQUES SANDSTONE. 165
CHAPTER XVI.
Formation No. 1 ; Chiques sandstone ; Hellam quartzite
of York county ; North Valley Hill sandstone of Ches-
ter county ; White Spot sandstone at Reading ; " P< ts-
dam sandstone" of the Reports of Progress; Upper
Cambrian quartzite of Walcott ; Sugarloaf sandstone of
Maryland.
It is best to get rid of the old name "Potsdam sand
stone" at the outset of a description of this the long con-
sidered oldest of our fossiliferous formations ; for there
seems to be no satisfactory evidence that the proper Pots-
dam sandstone of the Canada Line and Lake Champlain
extended as far south as southern Pennsylvania ; although
it seems to be traceable into the northwestern states.* It
is possible however that the friable sandstone beds of
Sand -Ridge in Nittany Valley, east of Bellfonte, Centre
county, may represent the New York Potsdam. They un-
derlie the Chazy and Trenton, as the fossils show ; but they
have limestones beneath them, as the South Ore Mine bo-
rings show.f
Chiques sandstone is not only the oldest name for our
formation No. I, but expresses the locality of its finest ex-
posure, the great rock mass which towers above the east
bank of the Susquehanna, for a mile above Columbia, and
ends abruptly at the Haldeman mansion and iron furnaces,
*The identification was based upon two facts, first that it lay almost im-
mediately underneath the great lime&tone formations (Calciferous, Chazy,
Trenton); second, that it contained worm burrows (Scolit/ius). But curi-
ously enough diligent search for Scolithus at the Potsdam village outcrops
have failed to find it; whereas Scolithus is very abundant in the Cambrian
quartzites, at different horizons, in eastern New York, and in various places
in Pennsylvania.
t E. V. d'Invillier's Report of Centre Co., T4, p. 31. See also Report T3,
p. 152, where M. Sanders' measurements on the Little Juniata make 5,400' of
upper limestone beds, about 40' of sandstone, and 1,160' of lower limestones,
bottom not reached.
166 GEOLOGICAL SURVEY OF PENNSYLVANIA.
where Chiquesalunga (Chikiswalunga, as Haldem an spelled
it) creek enters the river.*
Hellam quartzite is a name adopted by Frazer in his" York
county report, C2, because of the extensive spread of the
formation over Hellam township, where several large quar-
ries work it out, and its characteristic Scolithus fossils are
exceedingly abundant and admirably exhibited in place. f
North Valley Hill rock is the popular name for the for-
mation in its long outcrop through Chester and Montgom-
ery counties, where it edges the Welsh Mountain region
and looks down upon the narrow limestone valley of Coates-
ville, Downingtown, Conshohocken and Willow Grove.
At the White Spot on the mountain behind Reading it
has been famous since the early settlement of the Great
Valley. But so far from being an unique occurrence, we
now known from the long and minute geological surveys of
Prime and d'Invilliers that the formation spreads over the
whole range of the Highlands of Berks, Lehigh and North -
hampton in discontinuous outcrops and isolated irregular
patches, between which the older gneisses show. It very
generally forms the north slopes of the range, facing the
Great Valley : and rises also in more than one place through
the limestones of the valley itself 4
Primal sandstone is the name of it always used by
Prof. Rogers in his Geology of Pennsylvania, 1858. And it
would be a good name but for the fact that it is not an ordi-
nary sandstone but a quartzite ; and for another fact, that
it seems to take its place as the last not the first of the
great quartzites, being probably in what Walcott calls his
Upper or Potsdam subdivision of the Cambrian system.
There is reason for believing that it overlies in York and
Adams the upper strata of the South Mountain and has
*See description and section by H. D. Rogers, in Geol. Pa. 1858, page 193.
Also Dr. Frazer's Report 03, plate 4, page 108, and plate 5, page 112, from
photographs of the cliffs.
fSee the figures in Prof. Wanner's contribution to the Annual Report for
1876, part .
| See the Index sheet of the great topographical map of the region by
Prime and d'Invilliers, and the county maps accompanying Reports D, D2
D3.
NO. I. CHIQUES SANDSTONE. 167
nothing to do with the great quartzites of the Mount Holly
range on the Cumberland and Fayette side, except as be-
longing to the same Cambrian (or Huronian?) system.*
Prof. Rogers' lower primal slates are evidently Dr.
Frazer's phyllites.f
*In England the "Stiper Stones" of eastern Wales represents our Chiques
sandstone; a rocky formation 1,000' thick, vitrified by trap eruptions;
standing in picturesque pillars and castle-like masses of white crystalline
quartzite intersected by quartz veins ; passing geographically into coarse
grits and siliceous sandstone ; good road metal ; flagstones from a few inches
to 3' thick, separated by "way-boards" of sandy shale, or greenish white
unctuous clay ; ripple marked; showing casts of sea weeds (?) i. e. Cruzi-
ema, or Bilobites; also vertical worm-burrows (Scolithusa linearis) some-
times syphon-shaped at the bottom, and with trumpet-shaped mouths, (see
good picture of a slab on p. 41 of Murchison's Siluria, London, 1859); also
the characteristic shell lingula, in, over and beneath the Stiper Stone mass.
The Stiper Stone graduates downward into and in fact forms the upper part
of the Lingula flag formation. (See columnar section on p. 156 of Siluria.)
It graduates upward into the Llandeilo grey flags, slightly micaceous,
weathering brown (alternating with schistose darker beds) at least 3,000'
thick, and quite conformably overlying the Stiper Stones (Siluria, p. 48, 49).
The underlying Lingula flag formation {Upper Cambrian of Lyell) is
roughly divisible into upper, middle and lower ; the upper and lower full
of fossils, the middle almost destitute. (See Phillips' Manual, London,
1885, p. 45.) The upper and middle together are Sedgwick's Ffestiniog
group ; the lower is Salter and Hicks' Menevian group.
f Dr. Frazer says (General Notes, etc., Proc. Amer. Philos. Soc., Dec.
4, 1885, page 398) : "There are no good exposures of the Hellam quartzite
with the slate below it at any place in York county which I recall. On the
flank of the South mountain the quartzite is very much rent and crushed
into fragments, while of the small patch on the map about two miles west of
Case's ore bank (No. 8 on the map) no accurate dip was recorded. The
quartzite, of which a part composes the "Chikis mountain," exhibits in-
deed in its numerous foldings the rock called by Rogers "talcose slate" be-
tween its two principal beds of quartzite, but not appreciably lower than
the latter."
The quartzite mass seemed to Prof. Rogers to be double where it makes
the river cliffs a mile below the mouth of the Codorus. Here an upper
quartzite mass of beds "are underlaid by a tolerably thick belt of striped
slates; this again by a succession of thick sandstone (quartzite) and slate,
the latter predominating until we reach the limestone at New Holland.
Sometimes the slates clip slightly north from the axis and sometimes they
are inverted or dip towards it. Haifa mile above the furnace on Codorus
creek the compact white sandstone dips N, 60." (Geol. Pa., Vol. 1, p. 193.)
But from the above description it is evident that the "sandstones and slates,
are not beneath, but above, the quartzites, as Dr. Frazer's map shows.
168 GEOLOGICAL SURVEY OF PENNSYLVANIA.
No. I on the Susquehanna.
The Chiques quartzite is a very hard rock; of white or
grey color, often pinkish, brownish or blueish ; almost al-
ways crystalline ; and so brittle that the disturbed strata
have a smashed and confused appearance, sometimes leav-
ing the spectator in doubt which way the beds really strike
or dip at the special point of observation, although the run
of the outcrop as a whole is marked by a ridge of ground
more or less bold.
Prof. Rogers' description of the Chikis rock section from
Columbia up to Chikiswalung creek,- although not quite
comprehensible at one or two points, will serve to explain
the relationship of the exposed formations. SeeGeol. Pa.,
Vol. 2, page 193.
From the old railroad engine house in Columbia to the
furnace (1,100') appear (1) for 250', magnesian limestone
crystalline, mottled, dipping 50, S. S. E., beds obscured by
cleavages ; (2) for 250', ferruginous olive slate baked hard,
cleft with oblique steep joints ; (3) for 400', magnesian lime-
stone, more sandy, crystalline, cleft, white and mottled.
These are the lowest beds of the great Lower Silurian (Or-
dovician) limestone formation No. II, forming the valley of
York and the plain of Lancaster.
From the furnace to a little north of the second ravine,
2,500', is a fine natural section of "Upper Primal Slates."
apparently dipping all southward at say an average of 4o,
but there is a small compressed double fold at the tunnel ;
total thickness possibly 1,800 feet, but probably much less,
judging by their thickness "in the North Valley Hill of
Lancaster and Chester."
Chiques Rock is the square west end of Chestnut Ridge,
which runs due east 4| miles to Hempfield P. O. A fine
section of the formation has been made by the river, and a
beautiful anticlinal arch is plainly seen at the foot of din's
by the side of the road.* But it is not so easy to make out
*Here a cave of erosion, of no great depth, was inhabited by men, aban-
doned, filled up, and re-excavated by Prof. S. S. Haldeman, who was re-
warded by finding a multitue of human implements, etc. See his paper in
the Trans. Amer. Philos. Soc., Phila., with many plates and figures.
NO. I ON THE SUSQUEHANNA. 169
the true structure at the north end where another and col-
lapsed and overthrown anticlinal was seen by Prof. Rog-
ers, *and only the south half of one by Dr. Frazer, the north
leg being lost in a fault, f
These primal slates are greatly altered, hard, olive green
inside, weathering dingy brown, excessively cleft, dips de-
creasing from 80 to 65 at the contact with the underlying
quartzite at the second ravine.:}:
Here a low, oblique, irregular arch of quartzite (500'
across) lifts the slates ; with two gentle waves on its south-
ern side ; and its northern side completely inverted, so that
the beds all dip southward, the arch being tightly com-
pressed. In and under the arch of quartzite appears an
arch of slates. The quartzite beds only measure in all
about 25', the underlying slates say 300'.
From the arch to Chikis creek is 3,000', with three quartz-
ite exposures ; in the first one the quartzite, 27' thick,
rises at 60 (S.) ; then the slates, 300' thick, rise at 50 (S.);
then the lower or main body of quartzite rises at 50 (S.),
turns over sharply and descends again vertical, only 20 feet
of the top beds of this lower quartzite appearing in the
arch, white, without joint or fracture or trace of cleavage,
*See Geol. Pa., 1858, Vol. 1, page 193.
fSee Report C3, 1880, page 108.
fThe metamorphistn of the slates and quartzites which Prof. Rogers de-
scribes falls far short of that of the newer and older gneisses; and this is of
itself a guarantee of inferior age. It is however an additional proof, if any
were required, that 50,000 feet of the Palaeozoic formations, Ordovician, Silu-
rian, Devonian, Carboniferous and Permian, have been removed by erosion
from the York and Lancaster county region. The center line of the Dau-
phin county coal basin is only thirty miles distant (N.) from Cbickis Rock.
The forward thrust of the whole country shifted all the geological localities
out of Maryland into Pennsylvania. The movement took place upon the
floor of the gneiss, after the gneiss floor had lost more or less of its own
mass by previous erosion. Consequently it must have already suffered some
metainorphism by heat and pressure before the quartzite and primal slate
were deposited. The added palaeozoic time, heat and pressure increased
the gneiss metainorphism.
The pressure and heat to which Chikis rock was subjected at the close of
the Permian age amounted to say 50,000 tons to the square yard (90,000 Ibs.
to the square inch), at a temperature of more than 1,000 Fahrentheit; 600
being the melting point of lead, and 4,000 of iron. The metamorphic pro-
cess was consequently one of slow baking, under enormous pressure, in-
creasing through all the palaeozoic ages, reaching its maximum at the end.
170 GEOLOGICAL SURVEY OF PENNSYLVANIA.
the bedding barely discernable, but showing how plastic
it must have been to submit to such a lap while retaining
its solidity. The arch of overlying slates up the hill sides
is pressed into a sharp crest, and is full of cleavage.
A third "grand waving" arcli at the north end of the
rocks brings up the lower main body of quartzite, making
the fine cliffs back of the Haldeman mansion. The arch
at the road is 1,000' across. Its top shows two synclinal
waves. Its south beds dip 30 and then 45 (S.). Its north
beds plunge vertical, and probably bend back underground,
and rest their broken ends on the sides of the south dip-
ping limestones of the valley, as seen just across the creek.
Here the cleavage plains dip steeply N". Everywhere else
steeply S. about 80
The lower quartzite (with intercalated slate bands) can-
not be closely measured, but seems to be about 300'.
Some of the middle and lower quartzite beds are crowded
with Scolilhus Unearis, which are all nearly straight, and
sometimes furnished with a little knob at one end. This
knob is the cast of the funnel-shaped mouth of the worm's
burrow ; the best illustration of which is given by Walcott
on plate LXIII of his Monograph on the Olenellus Fauna
of the Lower Cambrian, published by the U. S. Geological
Survey, in 1891.
Dr. Frazer's general description of it as it exhibits itself
two miles north of Wrightsville ; in fragments on the sum-
mits of the range of hills from York to the Susquehanna ;
on Shunk's hill just south of York ; on the Pigeon hills
(line of York and Adams); in the outcrop three miles north
of Hanover Junction ; and on the south flank of the South
mountains, especially in Adams county ; is as follows : "a
very fine grained and compact rock, exhibiting generally
heavy bedding and joints of cleavage, the latter frequently
rendering its structure difficult to represent, awing to the
confusion arising from the surface planes. Its prevailing
color is flesh red or wine yellow, but it is sometimes beau-
tifully white." (02, page 108.)
An analysis of Chikis rock, by Mr. McCreath, shows :
THE CHIQUES RIDGE FAULT. 171
silicic oxide, 97.100; ferric oxide, 1.250; alumina, 1,390;
lime, 0.179 ; magnesia, 0.129; total, 100.148.*
The Chiques Ridge fault.
Along the north side of the Chiques Ridge runs the
south edge of the great limestone formation (Calciferols
Ila] of the Lebanon Valley. Along its south slope runs
a belt of hydromica slate 3 miles long; south of which
again runs a belt of the limestone under Columbia and
Mountville ; then a belt of the slate from Washington
Manor, east northeast, 3 miles ; then a belt of limestone ;
then the phyllite area ; then the gneiss. The two lime-
stone belts widen out into the great Lancaster limestone
plain. It is logical to consider them synclinal belts, sup-
ported on the hydromicas ; these supported by the Chiques
quartzite ; this by the phyllite formation ; this by the
gneiss of the Tocquan anticlinal.
If then the hydromica belt first mentioned ends in a
point (east) against the south side of the quartzite, and
does not encircle the east end, nor appear on the north side
of the quartzite belt (see Frazer 1 s Lancaster Co. map), the
natural explanation (although a very unsatisfactory one)
must be got by supposing faults.
A fault, however, undoubtedly ranges along the north-
ern foot of the Chiques ridge, between the limestone and
the quartzite, whether the quartzite beds simply are thrown
steeply upward (north) against the fault, or are doubled
over and crowded back downward into the fault. In the
former case we have an ancient basset edge wall of quartz-
*I well remember my astonishment, many years ago, when my dear old
friend John F. Frazer, Professor of Chemistry in the University of Penn-
sylvania, told me that he had just analyzed a specimen of Chikis rock sent
to him by our common friend, S. S. Haldeman, and found that it was not at
all a quartzite, but a silicate of lime. I never got an explanation of this cu-
rious adventure. Probably the specimen had been changed, and was not
from Chikis rock. Possibly there may be beds in the mass of the compo-
sition of which we are ignorant. Dr. Frazer adds that a quartzite from Geo.
Keller's farm, through which magnetite crystals are disseminated, is so
compact that its grains cannot be distinctly separated under a high power
lens; but that small irregular patches of limonite intersect the mass; while
in polarized light separate systems of concentric colored rings mark each
original quartz fragment. (02, page 108.)
172 . GEOLOGICAL SURVEY OF PENNSYLVANIA.
ite (facing north) now represented by the long line of fine
cliffs against which the river impinges at the mouth of the
Codorus, is deflected east along its base, five miles, to the
mouth of the Chiquesalunga, and then breaks through it to
Columbia. The line of the river proves the fault ; the rock
cliffs over the Haldeman mansion exhibit it.
Now, the slates along the south flank of the quartzite
ridge cross the river just above Wrightsville, edge the
south side of the triangular quartzite area in Hellam town-
ship, turn the west point of the triangle, and make its
northwest border back to the river, down the Codorus to
its mouth.
The geographical proof that the slates overlie the quartz-
ite is complete ; and establishes the correctness of Prof.
Rogers' upper primal slate formation.
The geological evidence is equally conclusive ; for the
general dip in the Chiques rocks is southward, under the
slates ; and of the slates southward under the limestone.
It is possible that the slates do actually crop out along
the north foot of Chiques rock ; for there is a concealed in-
terval of half a mile between the limestone and the quartzite
along the railroad, although in the bed of the river, at very
low water, Dr. Frazer says the two can bejseen only say 100
yards apart. But as the dips are nearly vertical, this in-
terval may mean nearly 300 feet of slate, even supposing
none of the slates are swallowed by the fault.*
There can be no doubt about the anticlinal structure of
Chiques ridge ; for, after running a straight east course for
eight miles, and losing itself beneath the Lancaster lime-
*C3, page 108. The first quartzite beds are seen dipping a little E. of S.,
nearly vertical, for a distance of about 1,400 feet down from the creek.
About 300 feet further south dips of 44 (southward) begin and continue200
feet. The next 500 feet is a synclinal trough holding chloritic and hydro-
mica schists ( Upper Primal slate) ; the basin being collapsed and over-
thrown, showing south dips of 48, 34, and then south dips of 70, 65.
The next 1.600 feet is occupied by a broad anticlinal (broken in on the crown)
with one plain S. 35 E. dip of 50 (at 700'), another N. 65 W. dip of 78
(at 1,000'), another S. 35 E, dip of 74 (1,250'), and another S. 30 E. dip of
76 (at 1,450.) Then descend the same hydro-mica schists with dips of S.
70 E. (!) 21, S. 23 E. 60, and S. 35 E. 50 (for 200' to Henry Clay fur-
nace=U5' of slates). Here an intercalated quartzite of peculiar aspect, S.
24 E. 24. Then come more hydro-mica for 800', and so on down the river.
NO. I EAST OF THE LANCASTER PLAIN. 173
stone plain, it reappears seventeen miles further on, upon
the same due-east course, at Laurel Hill, and begins to
spread around the Welsh mountain gneiss region into
Chester and Berks counties.
That it underlies the Lancaster limestone plain goes with-
out saying ; but we have visible testimony to the fact in the
shape of two outcrops near Manheim, 4 miles north of Lan-
caster, of oval form, each a ring of quartzite and slate
around a core of gneiss, and probably marking an elevated
point or hump high enough to reach the present surface
on the crest of one of those sharp collapsed or overturned
anticlinal rolls which pervade the whole underground of the
Lancaster plain.
No. I east of the Lancaster plain.
From Laurel Hill one belt of it extends along the north
flank of the Welsh mountains E. N. E. 12 miles to the ex-
treme east point of the county, and thence along the Berks-
Chester county line, partly in Berks, partly in Chester, 10
miles further, and is then, before it reaches the Schuylkill,
covered by the Trias.
The other belt passes south of the Welsh mountain, and
occupies in Chester county much of the surface of West
Cain and Sadsbury townships ; with three outlying smaller
areas in West and East Brandywine and Wallace. From
Sadsbury a continuous belt of it runs east northeast for 25
miles, through Valley, Cain, East Cain, Uwychlan, West
and East Whiteland, Charlestown and Tredyffrin town-
ships to the Schuylkill river at Valley Forge, where it is
covered by the Trias.
This is the well-known North Valley Hill, bordering the
Chester or (Downingtown) limestone valley on the north.
In all these outcrops of Lancaster and Chester counties
(except the three outlines above mentioned) the belt of
quartzite and slate runs between the gneiss and the lime-
stone, overlying the gneiss and underlying the limestone.
The reason of tlie exceptional cases is evident ; erosion has
removed the limestone from the quartzite patches, which
174 GEOLOGICAL SURVEY OF PENNSYLVANIA.
are themselves only remnants of a once universal outspread
of cjuartzite over the gneiss.*
In Montgomery county, the North Valley Hill belt of
quartzite undoubtedly continues beneath the Schuylkill
valley, on the same nearly east course, nearly to the Bucks
county line ; for we see it issuing from beneath the south
edge of the Trias in a series of four anticlinal spurs, or very
low hills, which sink diagonally (E. S. E.) beneath the
limestone of the valley, f Beyond the last spur the belt
itself issues from beneath the Trias at Fort Washington,
on the North Penn RR., and runs on six miles into More-
land township. Here it ends, spooning to a point and then
sweeping round the east spoon-point of the limestone (2 m.
E. of Pinetown) it returns westward as the south border of
the limestone to the Schuylkill at Conshohocken4
* Even in the case of the two uplifts of quartzite at Manheim, above-men-
tioned, they have the shape of rings around a nucleus of gneiss. And in
one place, near Green Bank P. O., 4 miles east of Laurel Hill, Lancaster
county, the area of quartzite is broken through by a surface patch of gneiss.
f This system of diagonal quartzite anticlinals separated by limestone syn-
clinals is a most curious phenomenon. Dr. Frazer has shown that it con-
tinues in force along the quartzite belt of Chester county. It proves a
widespread pressure movement in a N. N. E. direction ; and the movement
must be of a late date if we are to explain by it the astonishing anticlinal
and synclinal structure of the Trias country of Bucks "and Montgomery dis-
covered by Mr. B. S. Lyman and exhibited on his forthcoming geological
map of those countiea (Aug., 1871.)
J Here the South Valley Hill begins and runs west into Lancaster county.
We should of course suppose that this southern barrier of the synclinal
limestone valley would be made by the quartzite. But it is made of hydro-
mica slate.. Repeated reports have been made during the last fifty years of
the discovery of the quartzite ("Potsdam sandstone") at various points
along the South Valley Hill ; and no doubt specimens of quartzite have been
picked up, and even thin outcrops of thin quartzite beds among the slates
have been seen. But these amount to nothing. They cannot be accepted as
expressing with any certainty the reappearance of the North Valley Hill
belt on the South Valley Hill side of the limestone. It looks as if the North
Valley Hill rocks descend against a great fault, running along the foot of
the South Valley Hill and are there entirely cut off by it, probably thrown by
it (in company with the lower limestone beds) high into the air on the Del-
aware side of the fault
Now it is just at Conshohocken that the Schuylkill river breaks out of the
Chester county limestone valley to find its way to the sea, viz., in the short
interval between the east end of the hydro-mica belt of the South Valley
Hill coming from the west, and the west end of the southern quartzite out-
crop coming from the east. What does this mean ? Surely it is an added
NO. I. IN THE CHESTER VALLEY. 175
In a previous chapter has been given Mr. C. E. Hall's de-
scription of a belt of vertical quartzites running along the
south edge of Bear Ridge (older gneiss) from near Jenkin-
town, in Montgomery, to near Morrisville, in Bucks, in a
straight E. N. E. line about 16 miles long, with adjoining
outcrops of vertical limestone beds (in Huntingdon valley).
Here the quartzite (called 60 years ago eurite) is a sort of
itacolumite, although it scarcely at all exhibits the peculiar
flexibility of the well-known Brazilian stone. Perhaps the
true relationship of these beds 'to the Chiques qnartzite of
the North Valley Hill will never be quite satisfactorily
made out.
Rogers'" Primal in the Chester Valley.
Prof. H. D. Rogers studied his "Primal Series" very
carefully, and devoted many pages of his Final Report of
1858 to its description. He divided it into three formations :
a middle sandstone, with slates below and slates above ;
but warns his readers at the outset that all three divisions
are not always present, and that "in the more southeast-
ern zones especially, the Primal Upper Slate, and in some
localities the Primal White Sandstone would seem not to
have been originally developed, or to have been deposited
interruptedly. Even where present the recognition of the
slates is rendered in many cases very difficult from their
close approximation in aspect and composition to the more
ancient metamorphic schists." *
In the Willow Grove-Barren Hill outcrop, east of the
Schuylkill, it is most metamorphosed, resembling a regu-
larly bedded quartzose felspathic gneiss, decidedly crystal-
line, but the felspar crystals not so completely separated
from the quartz crystals as they are in gneiss or granite,
the silica being diifused through the felspathic mass with-
out much influencing its crystallization, "very much as the
sand occurs in the Fontainbleu carbonate of lime." So
proof of a great fault ; and of the total difference of the two formations ; and
of the futility of all endeavors to discover a southerly synclinal rise of the
quartzite along the South Valley Hill.
*Geol. Pa., Vol. I, page 149.
176 GEOLOGICAL SURVEY OF PENNSYLVANIA.
gneissoid is the rock, however, that it has been regarded as
a variety of eurite. It is traversed by innumerable joints,
dividing it into small rhombs. Along this whole Barren
hill outcrop this thin-bedded altered sandstone has in its
upper part much altered slate of a felspathic and talcose
character.* But there are no purely siliceous massive* beds
to be seen, as on the Susquehanna, and therefore no real
quartzite. The disappearance of the sandstone west of the
Schuylkill, along the South Valley Hill, he ascribes to an
actual thinning out.f
On the northern Montgomery Co. outcrop, between the
Pennypack and Wissahickon creeks, the principal mass is
an alternation of thin bluish-grey sandstone beds and still
thinner brownish sandy slate layers (much like the "older
primal slates" on the Susquehanna above Columbia) some-
times showing an incipient talcose crystallization (Gfeol. Pa.,
p. 154).
In the North Valley Hill west of the Schuylkill the
sandstone beds and upper slates run its whole length ; the
* Wherever talc is noted by Rogers, it is well to read either pholerite or
damourite; for analyses have cast doubt upon the magnesian character of
the mineral. This induced Dr. Frazer to adopt Dana's name "hydromiea
slate" for these apparently talcose beds.
f On this southern Montgomery Co. outcrop, between the Schuylkill and
Wissahickon, Prof. Rogers divides the formation into three, but places the
' sandstone on top, thus : The lowest or semiporphyroidal group, of altered
sandy slate, regularly laminated (bedded) alternately dark and light, so
thin as to have many in an inch, white earthy imperfectly developed felspar,
and dark earthy perfectly developed hornblende, with scattered concretions
of felspar from the size of a pin to a bullet. Maximum thickness at the
Schuylkill 300' (visible at Spring Mill 100'). Next, imperfect talcose and
micaceous slate, wavy, garnetiferous, as at the mouth of Aramink creek op-
posite Conshohocken. When less altered, an impure sandstone, holding im -
perfect mica and talc. Weathers to a greasy clay mottled deep red and bue,
evidently the source of the brown hematiteore deposits of the Valley. Large
segregated chunks of cherty quartz strew the ground. Thickness about 200'.
Upper member, the white sandstone of the Barren Hill anticlinal, thin-bed-
ded, yellowish white, very compact, with imperfect felspar crystals tend-
ing to rhombs ; the more solid layers seldom over two inches thick ; schis-
tose bands of felspar-quartz, with minute partings of mica and talc, holding
innumerable specks of pure black schorl (tourmaline). Thickness 35' to 40' ;
toward Willow Grove, 100' ; further east at least 300' (Geol. Pa., p. 155).
It is hard to believe that this represents the series on the north side of the
valley, which lies just as close to the northern area of gneiss as this does to
the southern.
NO. I IN THE CHESTER VALLEY. 177
sandstone lying directly on the gneiss ; the lower slates
wholly absent ; the sandstone holding a certain quantity
of purely siliceous beds, altered to quartzite ; some of the
beds showing needles of hornblende and a little crystal-
lized talc ; general dip about 70 to the south conforming
to the dip of the overlying limestone.
The white sandstone exhibits a remarkable constancy of
character from the Schuylkill to the Susquehanna ; some-
times more vitrified with imperfect felspar specks, partings
coated with talc, surfaces embedding minute crystals of
schorl ; sometimes less vitrified or cemented, more porous,
soft, crumbling, less flaggy, but still showing some talc and
schorl (tourmaline), (Geol. Pa., p. 156).
In the North Valley Hill the gaps of the East and West
Brandy wine, and at Gap station, show the beds to be about
100' thick, and the overlying slates a little more than 100'.
But in the South Valley Hill no continuous outcrop of it
appears, although it rises vertically next the limestone at
the foot of the hill near and west of Coatsville, projecting
conspicuously a rugged outcrop of beds in all about 30' or
40' thick, and of the usual character.*
The most easterly appearance of the Chiques sandstone
in the North Valley Hill of Chester county is a mile east
of Valley Forge at the east point of Mount Sorrow, where
it emerges ffom under the Trias, and where its lower altered
slates are half a mile wide. The sandstone increases going
west, along Mount Joy, to the west point of Tredyffrin
township (Ayre's store). At the Diamond Rock, where its
crevices hold fine rock crystals, the lower slates are seen on
its north flank Several anticlinal rolls, closely folded,
make the summit and south slope a broad outcrop of quartz-
ite beds. Here it is set back northward, and a new set of
waves begin. Most of it, however, has been eroded from
* About \\ miles east of Downingtown it was exposed in the road gutter
and in a well, and much decomposed and talcose. Opposite Spread Eagle
and Paoli, it was struck in T. Biddle's well, and its fragments lie in the soil
at the foot of the hill. (Geol. Pa., p. 166.) Mr. Rand reports other such
exhibitions. But it is still a question how far any of them warrant their
identification with the North Valley Hill rock, as they may be sandstone
intercalations in the South Valley Hill slates.
12
178 GEOLOGICAL SURVEY OF PENNSYLVANIA.
the gneiss, leaving only a south dipping outcrop going
down under the limestone. Between this and Lancaster
county its outcrop fluctuates in breadth, owing to local
waves, which, as Dr. Frazer shows, run obliquely and pro-
duce a toothed line of junction with the gneiss. Two or
three such anticlinal waves may be seen in the Brandywine
gaps, although their close compression makes all the dips
steep southeast, as shown in Prof. Rogers' cross sections.*
In the gap north of Downingtown the lower slate can
hardly be found ; and the quartzite is so complicated as to
seem a formation a thousand feet or more thick ; whereas
there are only about 100 feet of beds.f Here the first out-
crop against the limestone shows perfectly regular c[uartz-
ose layers with thin partings of white talc ; and in the rock
many needles of schorl, always broken by the plastic
movement of the matrix.:}: On the outcrops nearer the
gneiss the rock becomes more altered, a granular quartzite
holding specks of felspar and mica, a good deal like a fine-
grained white granite ; but the schorl identifies it.
*Geol. Pa., 1858, page 175. Fig. 21, section from Diamond rock across the
Valley south of Paoli. Fig. 22, section north of Coatesville, showing two
fine arches, one double crested. Fig. 23, section north of Parkesburg, show-
ing one sharp roll, and north of it a deep synclinal with its south side beds ver-
tical. Thus the belt varies in width from 400 to 1,200 yards. Sharp saddles
of the underlying gneiss also present themselves at the surface, splitting the
belt lengthwise ; and with the gneiss these saddles bring up the slates which
lie upon it (and beneath the quartzite beds) and so altered, crystalline and
gneissoid as hardly to be distinguished from the gneiss itself. East of the
East Branch Brandywine the upper and lower slates seem very thin; but
they thicken rapidly and steadily approaching the West Branch (Coates-
ville); which may help us to understand how the quartzite of the North
Hill (50' thick at Diamond Rock) is almost wanting in the South Hill,
while the lower slates, so thin on the North Hill side of the Valley, are so
very thick on the South Hill side. Prof. Rogers ascribes this to irregular
deposition ; but I think it must be due to some sort of pressure faulting ; if
in fact the formations be identical.
It is almost unnecessary to add that the limestone of the Valley is crum-
pled in the same manner as the quartzite and slate ; nor to urge the import-
ance of keeping in view all this movement as a wholesome check to any
theory of irregular, local, exceptional deposits.
f As described by Keyes in his paper on the Piedmont country of Mary-
land, quoted already.
Geology Pa., page 177. Prof. Rogers always uses this old-fashioned
name for black tourmaline.
NO. I IN BUCKS COUNTY. 179
No. I in Bucks county.
That the quartzite of the North Valley Hill, and of its
diagonal comb-teeth spurs in the valley east of Norristown,
passes broadly beneath the great Trias formation of Bucks
and Montgomery, making its descending floor, is proved by
its sudden re-appearance at the surface in Buckingham town-
ship, a few miles east of Doylestown. Here its outcrop
makes a bold low ridge nearly 4 miles long, running about
N. 40 E. with a belt of limestone on its northwest edge.
The limestone belt extends 10 miles to the Delaware river
at Centre bridge. Both formations are brought to the sur-
face together by a great fault, which will be described here-
after. As there are at least 15,000 feet of Trias south of the
fault, we are justified in saying that the quartzite floor,
which disappears beneath the Trias at Fort Washington,
must slope down northward at the rate of at least 1,000 feet
per mile, i. e., on a gradient at least 10. But as the average
dip of the Trias beds hardly exceeds 5 (although very varia-
ble, and hard to calculate by average) it would follow that
a very considerable amount of limestone overlies the quartz-
ite floor underneath the Trias region. Mr. Lyman's con-
structive sections however will make this interesting sub-
ject clearer.
No. I in the Highland range.
The quartzite floor emerges from beneath the north border
of the Trias in Springfield township, Berks county, where
the North Penn R. R. crosses the Lehigh county line. It
rises upon the south flank of the Highland gneiss, and runs
thus, eastward, for 13 miles to the Delaware river at the
county corner, between the gneiss and the synclinal lime-
stone belt across which the river cuts at Durham furnace.
The limestone belt spoons out, westward, at Pleasant Valley
P. O., and the quartzite (forking) surrounds its west end, and
puts another belt south of the limestone, and between it and
the gneiss of the Durham hill.
In Northampton county the quartzite formation must be
very thin, for although it undoubtedly forms floor of the
180 GEOLOGICAL SURVEY OF PENNSYLVANIA.
the numerous limestone valleys between and among the
Highland gneiss hills, it makes little show around their
edges, where it lifts its outcrops against the gneiss.*
In Lehigh county the quartzite crops out from beneath
the limestone and against the gneiss all along the foot slope
from Saucon creek westward past and around S. Bethlehem,
and along the south bank of the Lehigh to the west point
of the mountain two miles south of Allentown. f
In fact the Lehigh river, after passing Allentown, turns
at a right angle into a narrow synclinal trough of limestone,
floored with quartzite lying on gneiss. It is a curious
gateway between the Lehigh mountain (gneiss) on the south
bank, and the low gneiss hill on the north bank.
Five miles southwest of this right angle bend of the Le-
high, and in a line with the Lehigh mountain, there rises a
low hill of gneiss flanked with quartzite. a fine section
through which is made by the Little Lehigh creek.
Another outcrop of quartzite runs along the foot of the
mountain past Emaus (opposite the low hill aforesaid,
and two miles from it, with limestone between) for about
five miles. . ,
Another very short one is noticeable at the foot of the
mountain, three miles E. S. E. of Alburtis, and another a
mile west of Alburtis near the county line. With these
exceptions little or no quartzite has been reported in Le-
high county.
But in Berks county the quartzite makes a great show.;}:
A continuous outcrop of it faces the range of mountains
overlooking the East Penn RR. all the way from Alburtis
to Reading, 25 miles, ascending the vales between the
*For instance, at the river bank 3 miles below Eastern; on the slopes 4
miles east of S. Bethlehem ; on the slopes 2 miles south of Hellertown ; at
the west end of Chestnut ridge 3 miles west of Easton ; at the west end of
the strip of gneiss 3 miles northwest of Bethlehem ; and around the gneiss
hills in the bend of the river between Allentown and Bethlehem.
t At one place along this line there is a fine exposure of it, but only 25 feet
thick, dipping about 30' N. and laying directly and conformably upon the
gneiss. It is an exhibition well worthy of serious attention.
fThe mapping of Northampton and Lehigh was done by Prof. Prime, and
a subsequent revision of the mineralogy by Mr. C. E. Hall. The mapping
of Berks was done by Mr. E. V. d'Invilliers. This may account for the ap-
parent greater show of quartzite in Berks.
NO. I IN SOUTHERN CHESTER COUNTY. 181
ridges and spreading over the highest summits. A south-
ern belt crosses the Schuylkill a mile below Reading, and
encircles the whole of the Oley limestone valley. Another
surrounds the isolated little Dale Forge limestone valley.
Another borders the limestone of Seisholtzville, on the Le-
high county line. Three others border the limestone ex-
posures at Treichlersville, Churchville, Bechtelsville and
New Berlin, where it emerges from the north border of the
Trias. It is made perfectly certain by all this that the
Chikis quartzite formation once covered the whole High-
lands, and that it underlies now the whole Trias region
east of the Schuylkill. That it underlies the Trias west of
the Schuylkill, in Berks and Lancaster county, is demon-
monstrated in the same way by a long outcrop of it, be-
ginning 3 miles southwest of Beading, and running west 6
miles to the Reading and Columbia RR. at Fritztown,
curving northwest and west around the north flank of Mul-
baugh hill (gneiss), six miles further to the Lebanon line,
and so round south to pass out of sight under the Trias
south of Mulbaugh hill. But it is equally evident that the
quartzite is otherwise entirely covered by the limestone
under the whole Lancaster, Lebanon and Dauphin Trias
belt.
Before going west from Hellam township, York county, let
us see what evidence we have that the Chikis quartzite
once extended from the line of the Chester county valley
southward toward the Atlantic.
No. I in southern Chester county.
In Delaware county no rocks assignable to the Chikis
quartzite have been noticed by Mr. Hall; nor any in south-
ern Lancaster by Dr. Frazer. But in southern Chester Dr.
Frazer (certainly the best authority on the subject) has
mapped a considerable area of the quartzite between two
belts of limestone, and between two areas of gneiss, extend-
ing from the Pennsylvania and Delaware RR. south of Doe
Run P. O. eastward, for 8 miles, to a little beyond Red
Lion an area four miles wide between the limestone belts,
and running out east in a long straight line along the long
182 GEOLOGICAL SURVEY OF PENNSYLVANIA.
straight line of the southern limestone belt. Upland and
London Grove are in the middle of this area.
Another short narrow belt of quartzite runs from Kennet
Square along the Baltimore Central RR. west, along the
north side of another limestone belt. A similar outcrop
borders the limestone from West Grove station, westward,
for 3 miles. Another small triangular patch in Kennet
township has its south point within a mile of the Delaware
State line. Another more important outcrop surrounds the
limestone on Broad Creek in London and Britain townships,
and passes over into the State of Delaware.
It is evident, then, that if the rock of these outliers be
rightly identified, the Chickis quartzite had an unknown
extension southward, as it plainly had eastward.
No. I in southern York county.
In York county its former southward extension is guar-
anteed, but for a comparatively small distance, by one long
outcrop south of the Wrightsville and York limestone belt,
and by a great many isolated patches in the country north
of the phyllite belt.* Even inside the phyllite belt there is
noted on the map one spot of quartzite 3 miles S. W. of
Prospect, in Lower Windsor, 4 miles west of the Susque-
hanna ; and a small group at the Maryland line in the S.
W. corner of Manheim, and close to the north edge of 'the
gneiss. The absence of quartzite exposures on the surface
of the great Tocquan gneiss belt in York and Lancaster
counties, and in Delaware, Philadelphia and southern-
most Montgomery and Bucks counties, may be due to com-
plete erosion ; or it may be indicative of a supposible fact
that it was only through Chester county that the quartzite
and limestone formations at the beginning of the Palaeo-
zoic age were thickly deposited far southeast of the great
Palaeozoic region.
Rogers' Primal sandstone in its North Valley Hill char-
* It is possible that some of these isolated patches are short outcrops of other
quartzite beds intercalated among the hydromica slates. But they may be
sharp anticlinals penetrating the slates from below upward high enough to
reach the present surface.
NO. 1 IN SOUTHERN YORK COUNTY. 183
acter, was recognized by Rogers in the Peach Bottom lo-
cality, and for four miles down the Susquehanna river into
Maryland. He assigns its principal outcrop a thickness of
90 feet, and sees in the accompanying slates the upper and
lower members of his Primal Series, especially the lower or
South Valley Hill slates ; but as his principal exposure of
sandstone is in his opinion an overthrown compressed
anticlinal, some at least of the slates must fall into his
upper division.*
* I give three very interesting paragraphs on p. 189 of hisGeol. Pa., 1858,
verbatim for the readers' consideration :
"The next belt of strata cut by the river, and indicated on our section, ex-
tends from below Slate Point to the second canal-lock below the State line,
a distance of about four miles. The rocks here exposed are various forms
of mica-slate and talcose-slate, alternating with talcose white sandstone, cer-
tain outcrops of which bear the unmistakable characters of the Primal white
sandstone. One or two outcrops of chlorite-slate occur, and occasionally the
mica-slate graduates towards a micaceous quartzose gneiss. Much of the
finer-grained talcose slate is undistinguishable from rock, so-called, which
near the Schuylkill, and along the South Valley Hill, both east and west of
it, and also in the antichnals of the Montgomery and Chester Limestone
Valley, is seen in intimate alternation with the Primal white sandstone.
Either from the more frequent presence in this district of the middle part
of the Primal series, the White Sandstone group, or from a less excessive
degree of metamorphism, the strata here exhibit a far lower condition of
crystalline change than in some of the tracts further N., having fewer of the
features of true micaceous schists, and more of the characters of genuine
sedimentary sandstone. Indeed, at several places between Slate Point and
the State line, we meet with a rock which, in its composition, lamination,
colour, fracture and whole lithological aspect, is absolutely undistinguisha-
ble from the main bed of the Primal white sandstone, as it is seen in Edge
Hill and other notorious localities of this readily recognized rock. One of
the localities is just below Slate Point, the sandstone forming, in fact, the
south flank of the Slate Hill, and reposing, regularly bedded, immediately
upon the slate itself, which near the contact is highly nacreous, and in that
minutely wavy or crinkled lamination which usually denotes a metamor-
phism approaching the rock usually called Talc-slate.
" About 1700 feet further down the river, there is another outcrop of Primal
white sandstone immediately north of Hough's Run at the canal lock. Here
the rock is between 90 and 100 feet thick. It dips at the canal level 45 to 8.,
30 E. ; but rising into the hill it grows flatter until it becomes nearly level,
as if bending to form an anticlinal arch ; indeed, it is difficult to resist the
conclusion that these two south-dipping belts of sandstone are simply the
two abutments of a wide fold or flexure, the northern flank of which is in-
verted into a somewat steeper south dip than the southern. This view is
confirmed by the crushed and contorted condition of the dark slates which
fill the space between the outcrops of the sandstone. It is further confirmed
by the presence in this neighborhood, both within the supposed arch and at
184 GEOLOGICAL SURVEY OF PENNSYLVANIA.
The southwestern extension of the Chickis quartzite
formation in York and Adams counties, and into Maryland,
is in two lines : (1) by the Pigeon hills ; and (2) by the south
edge of the South Mountains.
No. I in the Pigeon hills.
The Pigeon hills are a range of high ground ranging N. E.
and S. W. through Jackson and Paradise townships of
York, and Berwick township of Adams county, at some
distance from and parallel to the limestone belt along which
the York Short Line RR., and its continuation, the Littles-
town Branch RR., run. Between the Pigeon hills and the
limestone runs a continuous belt of hydromica schist from
half a mile to a mile wide. At the foot of the hills, mark-
ing their southern limit, is a range of iron ore banks : S.
Emig's, W. S. Johnson's, And. Mengis, Mich. Meyers',
S. Roth's, J. Roth's, J. L. Miller's, Geo. Bechtal's, O.
Ferry's, Ashland Co.'s.* The Sprenkle ore is on the slope of
the hills, where they encroach so upon the limestone belt
as to reduce its breadth to a quarter of a mile.f
The Pigeon hills, beginning near Farmers P. O. 8 miles
W. S. W. of York, run on about 8 miles further into Adams
county, along the S. E. edge of the Trias. They are a belt
Slate Point above it, of a steep south-dipping cleavage, a feature quite usual
in the slaty rocks throughout the district.
"At other points further down the river, especially between Rock Run
and the State line, a material having all the aspect of the Primal white sand-
stone under a more extreme condition of metamorphism reappears. We
meet it again, though materially more altered and crystalline, about two-thirds
of a mile below the State line, and here, as we should expect, it is in con-
tact with a dark crystalline slate, precisely such as we find the talcoid slates
of the South Valley Hill, Chester county, where, in alternation with the
sandstone, they are more than usually metamorphosed. In truth, we en-
counter repetitions more or less frequent and distinct of this altered white
sandstone and its contiguous slates all the way along the river to the mouth
of the first stream in Maryland, more than a mile and half below the State
line. In other words, we may recognize these outcrops of the Primal white
sandstone throughout a belt nearly three miles and a half broad, from the
south flank of the Slate Point Hill to near the crossing of the great belt ot
serpentine."
*Frazer's Report C2, pages 55, 58, 63.
t C2, page 100. This slate ovqr the limestone, not between it and the quartz-
ite of the hill, dips S. 60 E. 78 ; the limestone under it dip S. 30 E. 69.
NO. I ALONG THE SOUTH MOUNTAINS. 185
of quartzite and slate ; the slate on the southern flank be-
tween the hills-and the York valley limestone, as at Colum-
bia j the slate belt being in fact traceable (with two or three
slight breaks where bridges of limestone cover the slates)
all the way to Columbia. Evidently a sort of anticlinal
axis connects the Chickis arches with the Pigeon hills : but
the country is too much crumpled to permit any geograph-
ical regularity to the outcrops. The slates are dark ; the
sandstone (quartzite) beds light colored and of various de-
grees of fineness and compactness.*
No. I along the South mountains.
No Chickis quartzite is seen in place along the southeast
foot of the South mountains in York and Adams counties;
but great quantities of quartzite fragments lie on the sur-
face of the hydro-mica schists as if the formation had been
wholly broken up and disintegrated. The belt of frag-
ments runs along between the Dillsburg limestone, marl,
trap and trias and the schists of the mountain in York
county ; and past Latti more, Idaville, Bendersville,Arendts-
ville, Cashtown, and so down south past Fairfield, down
Tom's creek to the Maryland line, between the trap and
trias and the mountain.
In Maryland the same exhibition is continued ; but after
a while hills of quartzite appear, and at last a bold high
ridge of quartzite called the Sugarloaf mountain, advanced
several miles in front of the Cotoctin mountain which is
the eastern ridge of the South mountain (Blue Ridge) mass
of the Potomac country.
The Sugarloaf sandstone (quartzite) is described as an
unmistakable sedimentary rock. Under the microscope it
shows no crystallization, not even an enlargement of the
quartz grains, although its cement is sometimes silica
(chalcedony), sometimes decomposed felspar (kaolin). No
new minerals have been generated in it. It has in fact
not suffered any appreciable metamorphism. The series
of sandstone beds (dipping east) pass upward through al-
ternations of clay sand and sandy slate, into the overlying
*H. D. Rogers, Geol. Pa., 1858, p. 195, 197, condensed.
186 GEOLOGICAL SURVEY OF PENNSYLVANIA.
slates and schists. They seem to be the same as the sand-
stone beds of the Cotoctin mountain on the west side of the
Frederick limestone belt, brought up by a great fault. To
the east of Sugarloaf however is the great phyllite country
of alternate belts of hydro-mica and chlorite slate ; and
these seem to be of later age than the Sugarloaf sandstone.*
In this opinion Mr. Keyes agrees with Dr. Frazer's views
as expressed in his third or Lancaster county report, al-
though in his earlier York and Adams reports, and in the
coloration of the York county map, a broad distinction is
made between the "hydro-mica schist" belt and the "chlo-
rite schist" belt to which in later years he applied the term
"phyllite." It is necessary to state the uncertainties more
in extenso in a following chapter.
No. I in middle Pennsylvania.
On the Little Juniata above the Tyrone Forges, in Hunt-
ingdon county, the great Nittany Valley faulted anticlinal
brings to the surface the bottom beds of the great limestone
formation No. II. It is the only spot in Pennsylvania north
of the South mountain range where we can look for the ap-
pearance at the present surface of the Chicques quartzite or
the hydro-mica slates above it ; and in fact, about three-
quarters of a mile above Birmingham, crushed and massive
grey sandstone strata are exposed (dipping 35 S. E.) for
150 yards. Under them red shales appear ; over them alter-
nations of sandy lime shales and limestones. These must
belong to Rogers' Primal series, although they are not met-
amorphosed, but only crushed a little by the fold of the
anticlinal and the slip of the great fault. f
* Keyes, in Bull. G. 8. A., II, 306, 320, and figured microscopic sections on
321.
t Geol. Pa. I, page 503. Dr. R. M. S. Jackson in 1837 thought these Pots-
dam. C. E. Hall supposed in 1877 that he found Potsdam fossils in them.
(Report T4, p. 152). Specimen 2,662 of the survey collections above the
Birmingham covered bridge is a white, compact fine-grained sandstone ;
Specs. 2,653 to 2,656, are sandstone ; Specs. 2,657 to 2,669, are a ferriferous
sandstone ; Spec. 2,661, marked "Potsdam" by C. E. Hall, is a hard grey
sandstone got below the bridge opposite the railroad station (T4, p. 365).
Prof. Rogers likened the solid sandstone beds to Medina.
ON SCOLITHUS LINEARIS. 187
CHAPTER XVII.
On Scolithus linearis.
Scolithus was for many years accepted as the fossil trade
mark of the Potsdam sandstone, and was supposed to stamp
with genuineness any outcrop, any specimen, in which its
notable form could be plainly seen. It is so prominent an
object on the surface of the cracked stone, it is so unmistaka-
bly unlike other fossils, it seemed at first to be so entirely
absent from the overlying Palaeozoic, Mesozoic and Kaino-
zoic formations, that the study of it by Haldeman in the
fallen fragments of Chicques rock near his home at Colum-
bia, on the Susquehanna river, and his description of it, in
1840, as the oldest fossil in the world, was hailed by geolo-
gists with enthusiasm.*
Of late years the gravest doubts have been thrown upon
the plant character of most of the most ancient "algae,"
* See his supplement .to Monograph of Limniades. Although he con-
structed the name from skolex, a worm, and lithos, a stone, he described it as
the stem of a seaplant, and made it at first a subgenus, and then a genus,
under Fucoides. H. D. Rogers mentioned Haldeman's fossil in his second
annual report, 1837, as a. marine plant, and suggested the name Tubulites,
which was not adopted. Hall's description of it is that of a plant . . . "nu-
merous linear stems, often extending to two or three feet in length. Ordi-
narily . . . like a series of small pins or pegs driven into the rock in a some-
what regular manner and at uniform distances. It preserves its distinctness
even when the surrounding rock is much altered . . . stained with oxide of
iron, and the rock cleaves more easily in that direction. (See Hall's Pal. N.
Y., V. 1, 1843, page 2 ; figures on Plate 1.) Even the famous fucoid of the
Bird's eye limestone (in No. II) Hall's Pkytopsis cellulosum, and Phytopsis
tubulosum, 1846, is now regarded by many as a worm burrow, in spite of the
cross connection of its stems and way in which they sometimes radiate from
a sort of center in all directions outward, curving and returning into each
other. But the internal fibrous structure, and the interlacing of the fibers
in mathematical forms, represented in the fine plates of Hall's first volume,
seems to place the organic (plant) structure of the Bird's eye fossil beyond
all reasonable doubt. ( See Pal. N. Y. , Vol. 1, Plate 8, Plate 9. ) The extrava-
gant conclusions of Nathorst, which would, if accepted, expunge seaplants
from palseo-botany, have produced a beneficial reaction towards a closer
study of these mysterious forms.
188 GEOLOGICAL SURVEY OF PENNSYLVANIA.
"fucoid" or "seaweed" markings, and as Etheridge says
in his edition of Phillips' Manual, p. 34, the " term Fucoids
must be modified or almost expunged from our nomencla-
ture, because nine out of ten of them are not casts of sea-
plants but of worm burrows. ' ' * The analogy of the present
lob-worms on all seacoasts seems to be a satisfactory explana-
tion of Haldeman's Scolithus, which has been found abun-
dantly in the sandrocks and quartzites at the base of the
Palaeozoic system from Canada to Georgia, and from Ten-
nessee to Wisconsin, and similar or allied forms in Scotland,
Ireland, Wales, France, Spain, Bohemia, Silesia, Finland
and Scandinavia.
In 1856 Salter named similar worm burrows of about the
same or still greater age in Shropshire, Arenicolites^ di-
dymus, because they were usually seen in pairs, joined by
a loop at the bottom, suggesting the idea that the worm
descended by one hole and returned to the surface by the
other4
In 1858 Kinahan found in the Lower Cambrian (Solva
group) of Brayhead, Ireland, curved trumpet-mouthed
burrow-casts, made by worms with tentacles. He named
them Histioderma hibernicum.
*Scolithus linearis (Hall) 1847, found in Formations Nos. I, II, III. Sco-
lithus verticalis (Hall) 1852, in Medina SS. No. IV (Pal. N. Y. II.) Sco-
lithus canadensis (Billings) 1862, in Potsdam No. I (Pal. Foss. I.) Sco-
lithus danieloi ( Tigillites danieloi of Renault) in the Potsdam of France
(Aguidam, <fec.); Scolithus (Tigillites) defontaines (Renault) in the Pots-
dam of France (Guichen, &c.); Scolithus (Tigillites) dufresnoyi (Renault)
in same. (Thesaurus Siluricus of Bigsby, p. 31);, Scolithus bohemicus (Bar-
rande); Scolithus cylindricus (Barrande) in Potsdam, D. d. 2 of Bohemia.
(Thes. Sil. p. 197.) See Hall's Pal. N. Y. I. 2.
fThe name Arenicola carbonaria was given by Lamarck to a worm bur-
row in the Wigan Coal measures of England as early as 1818, and this in-
duced Salter to substitute Arenicolites for Scolithus, for Cambrian forms-
American geologists, however, continue to use Haldeman's name, while
English geologists prefer Salter's.
J Arenicolites sparsus (Salter) was found in the Longmynd of Shrop-
shire (Thes. Sil., p. 29.) Arenicolites uricomiensis, found in the quartz-
ites of the Wrekin in Shropshire, is the oldest fossil as yet found in Great
Britain (or except the Eozoon canadense, in the world) provided the right
age has been assigned to these quartzites. (Etheridge. Phillman, p. 34.)
Thes. Sil. 30. Nicholson's Manual, 142. Etheridge's Phillips Manual,
34 in which it is wrongly given hibernica.
ON 8COLITHUS LINEARIS. 189
Salter's Scolecoderma tuberculata, 1866, in the Trema-
doc slates of Wales, is regarded by him as the membra-
nous tube of a mud worm.*
In the very old Cambrian rocks occur other forms, named
by Sternberg in 1833 Chondrites, the oldest forms of which
are now regarded as the casts of worm burrows, f
D'Orbigny in 1842 named a kind of worm burrow with
traces of a tube lining Cruziana. In the oldest Cambrian
(Lingula flags) Salter found Cruziana s&mtiplicata / and in
the nearly as old " Stiper stones " formation another species;
but the numerous forms of Cruziana named by geologists
occur chiefly in the Caradoc sandstone (Trenton period.):};
The confidence with which ScoiitTius linearis was at first
assigned to Potsdam sandstone is illustrated by W. B.
Rogers' paper on the Gravel and Cobble stone deposits of
Virginia, in which he describes finding, in 1842, a large peb-
ble of compact vitreous sandstone in a pile of paving stones in
Richmond, arid opines without doubt that the pebble had
come from the nearest outcrop of Potsdam on the west flank
of the Blue Ridge. Subsequently the cobble stone deposit of
Richmond was discovered at Washington, and multitudes
of Scolithus and other Palaeozoic fossils were seen in it.
Here it consisted of two gravels of very different ages, one
subcretaceous, the other post- tertiary, both giving Scoli-
thus, &c.
* He found a similar form, which he did not name, in the Caradoc. Hal de-
man's Scolithus chordaria, 1847, from Silesia, is put into the category of
worm fossils by Bigsby.
t<7. acutiangulus, McCoy, in Lingula flags; C. antiquus and informis,
Sternb. in Livonia ; C. regularis, Harkness, in Llandeilo rock ; C. tener and
tribulus, Eichw. in Finland and Esthonia ; C. ?, Salter, in N. Wales. But
Brogniart's C. antiquus was found in the uppermost Silurian (Ludlow)
beds. (Thes. Sil. p. 29.) The Devonian forms of Chondrites (andrea,
antiqua, major, minor, lineata,foliosa, nessigii, tceniola) are all placed among
plants by Bigsby in Thes. Der. Carb. 1878, p. 2.
tC. bronni, C. cordieri, C. furcifera, C. goldfussi. C. lyelli, C. prevosti,
C. st. hilaire (all of Rouault) ; C. carpetana, C. murchisoni, C. torrubice, C.
Ximenezii (all of DePrado) ; C. rugoso (D'Orb) ; C. harlani (Hall); &c.
(Thes. Sil. p. 30).
Proc. Boat. S. N. H. 1875 ; reprinted in Geology of the Virginias, 1884, pp.
709-913. See more of this under Wealden and Glacial ages. Prof. Heilprin
exhibited a pebble containing Scolithus linearis found in the Yellow Sand
formation of New Jersey, near Glassboro'. (Proc. Acad. Sc. Phila., May 5,
1885 ; and Amer. Nat., Sep., 1885, page 928.)
190 GEOLOGICAL SURVEY OF PENNSYLVANIA.
It would be strange indeed if worm burrows should be
confined to one geological age, and still more strange to
one petty formation. Nor are they ; for they have been
found in sandstone strata of all ages ; and their essential
identity with the ScolUJius linear is of the Chiques (Hal-
lam) quartzite is now generally recognized. Worms of
different species have different habits, and their burrows
differ; but the generic resemblance remains. Thus Sco-
lithus is common in the Portage formation '( VIII f} in
Bradford and Tioga counties, and in western New York.*
It has been seen also in some of the Coal Measure sand-
stones, in America and in England. But it is everywhere
abundant in the Cambrian quartzites of all the American
Cambrian regions. Whether Dr. Walcott is right or not
in carrying the Cambrian system so high as not only to in-
clude the Potsdam sandstone of New York, but also the
lower part of the Calciferous sandstone, some of the Cal-
ciferous beds are full of 8colit7ius.\
I have devoted an entire chapter to this fossil form, be-
cause the identification of Chiques rock with the Potsdam
sandstone of the St. Lawrence and Champlain country has
been hinged upon it, to the confusion of our earlier Palae-
ozoic geology in Pennsylvania. It has of course raised the
question why all the well-known fossil forms of the Pots-
dam were not discoverable on the Susquehanna. No other
fossil but scolitJius has been seen in the Chiques rock. Ob-
scure shell-like forms have indeed been seen by Prof. Warn
*H. D. Rogers, Geol. ot Penna,, 1858, Vol. I, page 296. "In the higher
part of the formation some of the layers contain a vertical fucoid, if it can
be so termed, a simple stem-like form, crossing the plane of the bedding.
This is evidently a species of Scolithus, and except that it is a little less regu-
larly cylindrical, resembles greatly the species so characteristic of the Primal
andstone."
f Brainard and Seeley who sub-divide the 1,800 feet of Vermont Calcifer-
ous into five stages, say that Scolithus does not characterize any single one
of the five, but appears abundantly in various horizons of D ; the most
abundant display of it seen by them being, however, at the bottom of C,
600' or 800' above the top of the Potsdam ; and yet pure limestone beds are
plentiful in B. (Bull. Geol. Soc. Amer., Vol. I, 1890, p. 510. See p. 4, Diet
Foss., 1889, Vol. a, page 943.) This should teach us to look for sandstone
beds in the body of our great Valley limestone formation ; and such are
found.
ON SCOLITHUS LINEARIS. 191
ner in the Hellam quarries, but none plainly enough to re-
cognize. Probably they are Cambrian fossils ; for the Cam-
brian rocks have furnished a plentiful supply.* It was
indeed the age of worms, as in an insect sense the age of
coal was also the age of Cockroaches ; but a solitary cock-
roach wing has recently been found in France in a sand-
stone of Silurian age. So, the Devonian age was one of
great armoured fishes; but fishes of that order have re-
cently been fonnd in Trenton rocks. The age of worms
now appears to have swarmed with living creatures of both
lower and higher grades. It is impossible to believe that
where the Hellam worm-burrows are in millions, no other
fossil forms can be discovered. It only requires sharp self -
trained eyesight to discover them. The South mountains
of Pennsylvania will probably prove to be a good collect-
ing ground for students of palaeontology; and perhaps even
the semi- crystalline region of the Philadelphia belt.
*Even in 1886, Walcott had defined 393 species (92 genera) of Algae (9),
Spongue (13), Hydrozoa (5), Crinoidea (3), Annelida (5), Brachiopoda (67),
Lamellibranchiata (1), Gasteropoda (29), Pteropoda (20), Crustacea (15),
and Poecilopoda (226). Of these, 76 (32 genera) were found in the Lower ;
107 (43) in the middle ; 213 (52) in the Upper Cambrians ; 14 genera were
common to the Lower and Middle, 15 common to the Middle and Upper, 11
common to the Lower, Middle and Upper, and 12 common to Lower and
Upper (Am. Jour. Sci., Aug. 1886, page 149.) But this arrangement has
been exchanged by him for another quite different (based upon his later
discovery of the subordination of the Middle to the Lower, or of the Ole-
nellus fauna to the Paradoxides) in his Monograph on the Cambrian re-
cently published by the U. S. Geol. Survey, 1891.
192 GEOLOGICAL SURVEY OF PENNSYLVANIA.
CHAPTER XVIII.
On Cambrian fossil life 'as known.
The great thickness of the Cambrian system may be
judged from the fact that Walcott assigns to the Lower
division of it (the Olenellus zone) in the two eastern coun-
ties of New York, Washington and Rensselaer (the nearest
Cambrian region to Pennsylvania as yet studied) a pos-
sible thickness of 14,000 feet ;* and to the Middle and
Upper divisions of it (Paradoxides and Orihis zones] an ad-
ditional 2,000 feet.f But in eastern Massachusetts, New-
foundland, Georgia and the Rocky mountains, the Cam-
brian would have a different thickness as a whole, and dif-
ferent thicknesses of its three palseontological sub-di-
visions.^: The fossil zones are no guides for us in the South
mountains (if the rocks there be Cambrian) because none of
the Cambrian fossils has as yet been found there, or indeed
anywhere in the state.
The abundance of marine vegetation and animal life in
the Cambrian age was long ago inferred from the copious
life of the immediately following Lower Silurian (Ordo-
vician) age. It began to be proved by discoveries in Bo-
hemia, Sweden, Wales, New Brunswick and Massachusetts.
*Amer. Jour. Sci., Vol. 35, 1888, page 242.
tThe sub-division is not made on the basis of stone character, but on the
stages of groups of fossils. He says: "About 2,000 feet below the summit of
the strata assigned to the Cambrian the fauna contains Olenellus asa-
p/ioides," <fec. The Fauna of the Lower Cambrian, in Tenth An. Rt. U. S.
Geol. Sur., Washington, 1891, page 583.
Jin both the "Eureka" and "Highland" sections the Olenellus zone is
comparatively narrow. In British Columbia it lies at the base of the Castle
mountain limestone, and beneath it are 10,000 feet (estimated) of dark clay-"
slates and sandstones (Pre-Cambrian or Algonkian) as in the Wasatch
mountain section. Walcott, in U. S. G. S., Annual Rt. X, 1891, p. 585.
Except Scolithus, and Prof. Wanner's undetermined shell forms in the
York county quarries, and perhaps the ribbon plants of the Peach Bottom
roofing slates.
CAMBRIAN FOSSIL LIFE. 193
It is now magnificently illustrated by Walcott' sand Ford's
collections in Vermont and New York, and by Walcott' s
and Dawson's collections in the Rocky mountains. Other
geologists have contributed their several discoveries ; so
that Walcott' s latest list (1891) includes 51 genera, 141
species, and 11 varieties. See Monograph, page 576.
Cambrian fossils are wholly of marine forms. No traces
of land plants or land animals have been seen in Cambrian
rocks.
True Seaweeds (algce) have not been certainly seen, al-
though it is impossible not to believe in their existence.
The so-called seaweeds (even the Cruziana) appear to be
trails of worms or of shellfish (mollusks).* Sponges were
very abundant. f Jellyfishes (Medusce) seem to have lived
even in Lower Cambrian times, and traces of their soft
forms are recognized on the clayslates and fine sandstones
of Sweden and on the Upper Cambrian rocks of Alabama.:}:
Even the modern Sea-sludge or Whale-food order of
creatures were represen ted. Graptolites also, those curious
and prolific leaf-shaped animals of Silurian times floated
on the surface of the Cambrian waters.! Corals (Actin-
*Matthew however has described what he believes to be true seaweeds,
from the St. John, N. B., rocks, under the names Buthotrephis antiqua,
PhycoideMa stichidifera, Palceochorda setacea, Hydrocytium (?) silicula,
and Microphycus catenatus. On Cambrian Organisms in Acadia, Trans.
Roy. Soc. Canada, VII, 1890, p. 144. Compare the fossil plant-like forms of
the Peach Bottom slate quarries in York Co., Pa., said by James Hall to re-
semble a Butrotrephis of the Hudson river formation (No. IV) more than
anything else.
f Protospongia is found in the upper beds of the Olenellus zone and also
in the Middle Cambrian of our east and west, and in Wales and Sweden.
Leptomitus is wholly Lower Cambrian. There are two other genera. Wal-
cott, page 587.
{The Swedish geologist, Nathorst, thinks that the once supposed seaweed
Eophyton is the cast of the trail of a jellyfish moving over the sea-bed. Pos-
sibly Dactyloides aster aides, an American species, may be so explained. It
is very remarkable that nothing like a Medusa has been found in the Palae-
ozoic and Mesozoic rocks, nor until we ascend to the Upper Jurassic litho-
, graphic slate. Walcott, p. 587.
Matthew describes Monadites globulosis, M. pyriformis, M. urceifor-
mis and Radiolites ovalis. Camb. Org. Acadia, 1890.
|| At least two kinds, Phyllograptus and Climacograptus. Matthew has
assigned two Middle Cambrian forms to the genera Dendograptus and Pro-
tograptus.
13
194 GEOLOGICAL SURVEY OF PENNSYLVANIA.
ozoa) had hardly begun to appear.* Sea urchins existed
early and became numerous in the Middle Cambrian, f
Worms were infinitely numerous, swarming, trailing and
burrowing over and in the sea bed and shore sands, from
the beginning to the end of Cambrian times, and under-
going no change so far as the casts of their tracks and bur-
rows can teach us anything of their character. They have
been grouped in four genera : Planolites, Hilminthoi-
dichnites (lobworm tracks), ScolitTius and Oruziana.
The BracJiiopod shell life of Cambrian times was abund-
ant ; ten genera (and 29 species) are known in the Lower
Cambrian (Olenellus), zone, viz., Lingulella, Acroleta,
Acrothele, Iphidea, Kutorgina, Linnarssonia^ Obolella,
Ortkis, Orthisina, and Camarella.% These have no special
embryonic traits of character in the Darwinian sense, lead-
ing to higher development in the Middle and Upper zones ;
but after that, in Lower and Upper Silurian times, the
superior articulated families (Orthidse and Rhynchonel-
lidse) predominate over the inferior inarticulate fam-
ilies (Obolellidse, Siphonotretidse and Lingulidse) which
* "The first true corals .... occur near the base of the Silurian fauna."
It was disputed whether Archceocyathus was a sponge or coral. ButHinde
and Walcott agree in placing it among the Zoantharian families, allied to
the perforated corals. In the later Cambrians no Archosocyathus is known
except Matthew's doubtful A. pavonoides from the Paradoxides zone at St
John. Walcott, p. 588.
f In the Lower Cambrian a few scattered plates of a Cystid, perhaps an
ISocystites, are all we know about the beginnings of the Echinodermata.
Walcott, p. 588.
| Lingulella : of four genera three occur in the Paradoxides zone. A cro-
teta gemma ranges from the base of the Lower into the Upper Cambrian.
Acrothele subsidua ranges through Lower and Middle, and A. matthewi in
the Middle. Iphidea is Lower Cambrian in Labrador and Middle in Arizona
and Sweden. Kutorgina labradorica, stissingensis, pannula, occur in
Lower and Middle, the first with a wide geographical range in the Lower
zone. Linnarssonia sagitalis (var. taconica) came late in the Olenellus
zone and lived on with the Paradoxides. Obolella has 6 species in the Lower,
none in the Middle, but some in the Upper zone. Orthis salemensis and
highlandensis (the broad and the narrow hinge types) of the Lower zone is,
not known In the Middle, but recur in Silurian strata. Orthisina orientahs
of the Lower zone is very like the O. pepina of the Upper ; and O. festinata
of the Lower very like O. exporecta and O. billingsi of the Middle zones.
Camarella antiquata and minor -of the Lower zone have no known exist-
ence or representatives in the Middle and Upper zones. Walcott, p. 588, 58&
CAMBRIAN FOSSIL LIFE. 195
abounded in the more ancient Cambrian times, indicating
a general law of progressive evolution for the whole class.*
Lamellibranchiate shells were scarce in Lower Cambrian
time. The class seems to have sent three forerunners to
announce its coming at a far distant subsequent date.f
Gasteropod shells of 6 genera (13 species and 5 varieties)
have been collected from the Lower zone in America alone,
viz : Scenetta, Stenotheca, Platyceras, Pleurotomaria, and
Straparollina. These belly-creepers with their conical or
horn-shaped, sharp-edged and sharp-pointed shells, must
have scratched and furrowed the Cambrian muddy sand,
leaving those marks on its layers which in too many in-
stances have been taken for fossil seaweeds and even land
plants.:}:
Of Pteropods, winged shells, the Oldest Cambrian sea
was full. Four genera : Hyolithes, HyolitTiellus, Coleo-
loides, Satterella, embraced at least 15 species.
* Walcott, p. 587. Superior and Inferior are terms which beg the ques-
tion. It is more likely that hinge or no hinge was a point in dispute settled
by the habitat of each species and the adaptability of the shell to the food
which that kind of habitat supplied, or to the comfort of housekeeping there.
f Fordilla troyensis and Modiolopsis prisca and an undescribed species.
These came and disappeared. None have been seen in the Middle or Upper
zones. Suddenly a group of species is seen in the Welsh Arenig rocks
(Lower Silurian). In Devonian times the class flourished in all seas.
JThe Scenellas of the Lower zone are represented by at least one species
in the Middle zone, and by simple Patelloid shells in the L T pper zone.
Stenotlieca rugosa of the Lower zone is closely allied to 8. acadica of the
Middle zone. A small Platyceras in the Lower zone is represented by P.
romingeri in the Middle ; and one single species found in the Upper zone
passes the genus on upward into the Ordovician (L. Sil.) age. Pleuroto-
maria attleboroughensis of the Lower zone "does not appear to have a rep-
resentative before reaching the Lower Ordovician fauna." Straparollina
remota of the Lower zone has no known connection with the Ordovician.
Hyolithes princeps, a large and abundant shell, had a range from Ne-
vada to Newfoundland, and seems to have lived into the Newfoundland
Paradoxides (Middle) zone ; and it differs only in details from the Bohemia
H. maximus of that zone. H. americanus of the Lower zone is closely
allied to H. acadica and H. primordialis of the Middle zone. H. billingsi
is found in Lower and Middle, in Labrador, New York and Nevada. H.
similis is like H. primus of the Bohemian Middle zone. H. communis,
impar, quadricostatus, terranovicus have not yet been found in the Middle
zone. Hyolithellus and Coleoides are not certainly known in the Middle
zone. "Salterella oi the Lower Cambrian is not again met until the Ordo-
vician fauna is reached, and there very doubtfully." Walcott, p. 590.
196 GEOLOGICAL SURVEY OF PENNSYLVANIA.
Of Crustaceans five genera (8 species have been found in
the Lower Cambrian zone, viz., Isoxys, Leperditia, Aris-
tozoe, Nothozoe and Protocaris. It is as wonderful as any-
thing else in geology, finding thus a world of schrimps in
the first hour of the long day of the planet's life.*
Trilobites^ of 16 genera (53 species), constitute nearly
one- third of the entire Lower Cambrian fauna ; trilobites
with eyes, and trilobites blind ; trilobites with facial sutures,
and trilobites with unjointed faces or head shields : Ag-
nostus (3), Microdiscus (8), Olenellus (7), Olenoides (3),
Zacanthoides (2), Bathynotns (1), Avalonia (1), Cono-
coryphe (2), Ptychoparia (10), Agraulos (3), Crepicepha-
lus (2), Oryctoceplialus (1), Anomocare (1), Protypus (4),
Solenopleura (5 species), f
*Of the true crustaceans Leperditia dermatoides has two representatives in
the Middle zone. Isoxys is a new genus. Aristozoe has not been found in
the Middle zone, but in Europe it has many Silurian species. Of the Phyl-
lopod crustaceans Protocaris marshi is the earliest known, the next being
Hymenocaris vermicauda of the Upper zone. Walcott, p. 590.
t Agnostus, which has been theoretically considered the lowest and oldest
and ancestral form of all the trilobites, seems not to have lived early in the
Obolellus zone; undoubted specimens having been found only in the
upper part of the zone and with Middle Cambrian forms ; for Ford's Ag-
nostus nobilis is probably Microdiscus. In Sweden it seems also to belong
more to the Middle zone.
Microdiscus, with its 3 or 4 segments and no eyes, is found at the base of
the Lower zone, a,nd with so many species (8) must have had a long previ-
ous existence, coming to a maximum development in the Lower and fading
away in the Middle zone (as the Agnostus increased in importanc), and
being represented in the Upper zone by the solitary Pernphigaspis bullata
of Hall (while Agnostus lived on into Ordivician, L. Silurian, times).
Olenellus is known from all Lower Cambrian areas except New Bruns-
wick. It varies so that Walcott has grouped some of its species in a sub-
genus (Mesonacis) and Matthew has proposed Holmia to include O. kjer-
ulfi. It differs from Paradoxides in having no true facial sutures, in the
lorm of the central portion of the head, and in the form of its eyes. 0.
thompsoni differs most strongly from Paradoxides, which latter has nothing
at all like the long-tail spine (telson). But O. (Mesonacis) vermontana
with its typical Paradoxidean tail-piece (pygidium) links the two groups of
species of Olenellus together. Walcott invites attention to the fact that there
is a depressed line on the under side of the head-shell of Olenellus corres-
ponding to real suture in Paradoxides. Also, that Olenellus resembles our
King Crab (Limulus) in haAang well-developed eyes without having facial
sutures, not to speak of its tail-spike. He thinks the Newfoundland O.
broggeri as highly or more highly organized than any Paradoxides. Amer-
ican paleontologists, he adds, have considered Olenellus the descendant of
CAMBRIAN FOSSIL LIFE. 197
The study of the Olenellus fauna proves that an immense
time had already elapsed since the beginning of life on the
planet, Daring Cambrian times the evolution of life pro-
duced almost no new classes of living creatures, but only
new generic and specific variations of those which were al-
ready in existence. The most notable apparent exception
to this statement is found in the subsequent appearance of
the class of Cephalopod shells (Orthoceras, Lituites, etc.),
none of which have as yet been found in rocks below the
Silurian.* It is hardly necessary to add that nothing is
known of fossil lishes in the Cambrian, much less of any
Paradoxides, but it has turned out that Olenellus lived first. The student
of Evolution may profitably ponder on the paragraphs of his 592d page.
Olenoidcs marcoui is the only species found in the lower portion of the
Olenellus zone (the other two border on the Paradoxides zone) and seems
closely related to O. nevadensis of the Paradoxides zone. Zacanlhoides
eatoni and levis serve to unite the two zones. Bathynotus, Avalonict,
Oryctocephalus and Protypus are genera confined to the Olenellus zone.
The blind Conocoryphe trilineata, and reticulata are two of the best-
marked types 01 the Lower zone, but are closely related to the blind elegans
and coronata of the Middle zone.
Ptycoparia has nine species, all more or less closely related to Middle and
Upper Cambrian forms. The Lower Cambrian Agraulos slrenuus is rep-
resented by the Upper Cambrian A. socialis. Ellipsocephalus has a species
in the Lower and in the Middle zones. Crepicephalus augusta and liliana
are also Upper Cambrian, but have not been found in the Middle zone.
Solenopleura is also well developed in the Middle zone.
Walcott concludes (page 593) that we have a poor knowledge, as yet, of
the Middle (Paradoxides) fauna and may expect great discoveries to bo
made somewhere "on the western slope of the Apalachian shore, and on the
west coast of what then existed as the North American continent." The
Paradoxides fauna is merely a contribution. Surely the Lower Cambrian
creatures continued in existence longer than the rocks as yet have shown.
For instance, what became of the Archseocyathine corals of the Lower
Cambrian? Obolella had a fine development in Upper Cambrian time,
why is it almost completely absent from the Middle Cambrian rocks?
What happened to the Brachiopod shells as a class to render the number of
both their species and individuals smaller in Middle Cambrian time than
before? We have Lamelli-branch shells from the Lower; none Irom the
Middle. So also of the Gasteropods Pleurotomaria and Straparollina, and the
Phyllopod crustacean Protocaris marshi, "The cause of the abrupt change
from the Olenellus to the Paradoxides faunas is not yet fully recognized.
While a considerable number of the genera pass up, very few of the species
are known to do so, and in none of the sections has there been found a com-
mingling of the characteristic species of the Lower and Middle faunas."
(Walcott, page 594.)
* Walcott, page 595.
198 GEOLOGICAL SURVEY OF PENNSYLVANIA.
fossil vertebrates of a higher order, reptilian or mammalian.
But whereas only three or four years ago it was disputed
whether our Perry county Upper Silurian* fish spines and
plates (the oldest known to science) were not the spines and
plates of crustaceans, and whereas now true fish remains
have been found in the Lower Silurian (Ordovician) Tren-
ton limestone in the Rocky mountains,! it is easy to fancy
that cephalopod shells 'and ganoid fish may have lived
even in Cambrian times. As yet no air-breathing land ani-
mal remains have been discovered in any rocks older than
the Carboniferous ; but, considering the extreme difficul-
ties attending their preservation, as compared with the easy
and safe burial of water animals, it is not at all a wild con-
jecture that some sharp eye will light upon the traces of
their existence in earlier ages4 Only a few years ago the
Cambrian rocks were supposed to be non-fossiliferous. I
have inserted this chapter on Cambrian fossil life to guide
and stimulate students of geology in Pennsylvania, especi-
cially the more youthful, curious and keen-sighted, to a
closer examination of our so-called "Azoic" or "No-life"
formations.
*See Claypole's discoveries in the Clinton formation No. V a. in Report F2.
f See C. D. Walcott's descriptions read at Washington, August, 1891.
JIf the discovery of a Silurian cockroach wing in Calvados, France, be
genuine, there was a Silurian world of land insects, and of course of land
animals to devour them. If Lesquereux was not mistaken about his fossil
Silurian land plants, there must have been land animals living upon their
fruit or foliage. In all ages foods have been followed (or accompanied) by
feeders. On the other hand, feeders presuppose foods. What did the Lower
Cambrian worms, polyps, shells and crustaceans live upon ? Certainly not
upon mineral matter. Worms pass vast quantities of mineral matter
through their intestinal canal and leave it packed behind them in their bur-
rows, and this packing constitutes mostof the "fossil cast. " But they do this
in order to suck from the surface of the grains of sand and mud organic
matter which must have belonged to other creatures either alive or dead.
If alive, then microscopic animalcules. If dead, then the decomposed
tissues of other worms, shell-fish, etc., absorbed by the sand and mud.
But the first worms must have found living food. If the worms came first
and the polyps and mollusks afterwards, then the beginnings of life must
be conceived of as microscopic, cellular and vegetable ; in other words, an
Algoid or seaweed world, feeding on the chemical elements of the rocks
held in solution by the ocean water ; therefore casts of sea weeds in the oldest
rocks must be realities and not mechanical imitations.
SOUTH VALLEY HILL SLATE BELT. 199
CHAPTER XIX.
South Valley Hill slate belt.
Before leaving the dark geology of southern Pennsyl-
vania to enter upon the brilliantly illuminated geology of
the middle region, something more must be said of those
enigmatical belts of hydro-mica slates which Prof. Rogers
placed as his Upper and Lower Primal slates, above and
below the Cinques quartzite (N. Valley Hill sandstone)
which Dr. Frazer places wholly above it and which Mr.
Hall placed still higher, above the great limestones, as
Hudson river slates in an altered condition.
In York county the last theory receives no support. A
belt of hydro-mica slate surrounds the Hellam quartzite
area between Chiques rock and York, and is surrounded by
the limestone of York valley and the Codorus. The hydro-
mica beds are evidently above the quartzite and beneath the
limestone ; and they run on between two belts of limestone
to the Pigeon Hills, and along the south side of the hills
into Adams county, where they enclose the southwest end
of the limestone area, and, uniting with the broad belt of
hydro-mica country south of the limestone, pass into Mary-
land, where Mr. Keyes finds them overlying the Sugarloaf
and Cotoctin quartzite.
South of the York limestone belt at Wrightsville, on the
river opposite. Columbia, a hydro-mica belt a third of a mile
wide between the limestone and a long outcrop of quartzite
runs west to the South Branch Codorus, where its width is
five miles, widens to six miles at Xenia, and contracts to
three miles at the Adams county line. Many isolated out-
crops of quartzite are located on the map inside this belt,
and they should represent sharp anticlinal rolls of quartzite
exposed by erosion.
The phyllite ("Chlorite schist") belt, already described
200 x GEOLOGICAL SURVEY OF PENNSYLVANIA.
in a previous chapter, borders this great hydro-mica schist
belt on the south, and two long prongs of phyllite country
penetrate the hydro-mica belt, one pointing west towards
the S. Br. Codorus, the other pointing east to the river a
mile below Wrightsville, both on one line, and the two rep-
resenting (theoretically) an eleven-mile long anticlinal ex-
posure of the phyllites from under the hydro-micas.
Around the east point of the east phyllite prong at the
river below Wrightsville, and along its southern side from
the river west for six miles, there runs another belt of
hydro mica slates, bordered on the south by the limestones.
As an outcrop of quartzite borders the north side of the
phyllite prong and laps around its pointed end onto its
southern side, it seems evident that the hydro-mica over-lie
the quartzite and under-lie the limestone.
But why is there not such an outcrop of the quartzite
between the phyllites and hydro-micas along the whole
contact line across the county? There is but one answer :
The quartzite is an insignificant formation, an irregular de-
posit, thin here, thick there, absent altogether elsewhere,
and in fact generally towards the south. This seems to be
the case in Chester county, and especially in southern Lan-
caster. But if so, then the contact plane of hydro-mica on
phyllite must be insignificant, unreliable and deceptive ;
and the contact line between the two great belts in York
county can hardly be relied upon as accurate. In fact the
distinction between the Chlorite schists and Hydro-mica
slates is not recognized by the Maryland geologists ; and
Dr. Frazer says that chlorite slates occur in the hydro-mica
belt. He establishes the distinction on a general larger
proportion of magnesia in the lower and less in the upper ;
and on the local separation of the two by the quartzite
beds. That is precisely what Prof. Rogers did in con-
structing his series of Primal lower slate, Primal (middle)
sandstone, and Primal upper slate. But then, the chloritic
phyllites of York become the Primal lower slate of the
South Valley Hill in Chester. Whereas I understand Dr.
Frazer' s Chester county report .to make the South Valley
Hill a belt of the hydro-mica slates.
SOUTH VALLEY HILL SLATE BELT. 201
I see but one solution of the problem, which if correct
will conciliate the apparently contradictory identifications
of these two able geologists, viz., that both the lower more
magnesian and upper less mftgnesian series are present to-
gether in the South Valley Hill.*
The South Valley Hill slate belt is two miles wide at the
east end of Chester county, and the slates stand vertical.
That means 10,000 feet of slates ! To diminish this enor-
mous thickness to agree with his observations on the oppo-
site side of the valley (in the North Valley Hill) Mr. Rogers
supposed many tightly-compressed rolls. Certainly two
such rolls show in the double-spurred east end of the hill
at the Schuylkill.f But two rolls, whether anticlinal or
synclinal (and there is not room for more) will not reduce
the thickness to one-fourth. There would still be more
than 2,000 feet of slates. $
Opposite West Chester the belt is three miles wide ; op-
posite Coatesville, five miles wide ; before reaching the
Lancaster line, still wider ; and so continues, covering much
of the southern townships of Lancaster ; a region where
Dr. Prazer does not feel justified in mapping a contact line
between his chloritic series and hydro-mica series. In
*In this case however we must neglect Prof. Rogers' obscure outcrop of
the Primal sandstone at the north foot of the hill, along the border of the
limestone.
fThe two "synclinals" on which C. E. Hall relies for placing the slates
over the limestone ; the two "anticlinals" on which Dr. Frazer relies (in this
vicinity) for placing the slates beneath the limestone.
J Rogers conjectures that his Primal Lower slates between the Brandy-
wine and Adams county may be 2,000 feet thick ; in Virginia 1,200, with 150
additional as a conglomerate base which does not appear in Pennsylvania.
His Primal Sandstone, around the outlying limestone patches of southern
Chester, in the Street road and in Dochranaman hill, thin; then at Peach Bot-
tom on the Susquehanna, 90' ; in Chiques rock, U. SS. 27', slate parting 300
L. SS. with bands of slate, 300', total 627 ; at Parkesburg, Chester Co., U. SS.
20 , slate 300', L. SS. 50, total 370 ; at Coatesville, Chester Co., U. SS. 40', slate
70', L. SS. 15', total 125 ; at Edgehill, 300' ; at Willow Grove, 100' ; on Schuyl-
kill and Wissahickon, 40' ; Durham on the Delaware, 100 ; Chesnut Hill
north of Easton, 100' ; below Reading thicker, but too much crumpled to
measure.
His Primal Upper slates, wanting east of Willow Grove; Barren Hill,
thin ; Diamond rock and Paoli section, 300 ' ? ; Coatesville, 700' ; Parkes-
burg, partly visible, 300'+; Columbia and Chiques about 1,000'. (Geol.
Pa., 1858, page 122.)
202 GEOLOGICAL SURVEY OF PENNSFLVANIA.
fact hydro-mica slates with chloritic interpolations and
chloritic slates with hydro-mica interpolations can be called
"phyllites" with equal propriety (are so called in the
Maryland survey) and alike belong really to one system of
sediments, more or less magnesian.
Now, it would be wonderful indeed, if there were not
sand beds in two or three thousand feet of mud deposits.
When the magnesian muds were altered into chlorites and
the potash-soda muds into hydro-micas, then necessarily
the sand beds became quartzites. So we ought to expect
sporadic quartzite beds in the slate belts. The occasional
quartzite spots on the York county map in the phyllite
belt, and much more numerously in the hydro-mica belt,
may therefore have nothing to do with the Hellam-Chiques
quartzite, which, itself, as we have seen, actually plays the
same role of irregular distribution over its original floor as
all lenticular sand deposits do of every age.*
The South Valley Hill hydro-mica schist belt from the
Delaware- Chester county line west to the Brandywine has
a south border fairly denned by a straight range of ser-
pentine outcrops and limestone quarries. " The line crosses
the railroad south of Patton station, cutting across the north
end of West Chester, to the Brandywine at the mouth of
Valley creek, and the west branch at Embreeville ; passing
along the north side of the Doe run limestone and the little
gneiss area of Buck run. But 'hence westward through
Londonderry, Upper Oxford and Lower Oxford "there is
an indefinable transition from the belt of mica slate to the
felspathic micaceous gneiss country which borders it on the
south f
*The Oriskany sandstone, Formation No. VII, is a notable example of
this general law, as we shall see in a future chapter. If it had been pre-
served from erosion in a metamorphic region it would be almost a facsimile
of the Chiques quartzite. The Chiques quartzite ought not to be regarded
a s a unique, nor reasoned on as a universal formation of recognizable class-
ical age and place in the great series. That would be to repeat the old error
of the "Potsdam sandstone." It is but one of many, and our sketch of the
South mountains in a previous chapter shows its insignificance in compari-
son with the huge quartzite formations underlying the hydro-mica and
chlorite slates of that range of mountains.
fCriticising the map of Chester county which he was unable to revise be-
fore its publication, Dr. Frazer writes: "The chloritic and hydro-mica
SOUTH VALLEY HILL SLATE BELT. 203
The general tint of the slates is greenish, and the beds
are frequently separated by lenticular beds of light-colored
or pure white quartz. The slates along the southern edge
of the belt are somewhat garnetiferous ; and at two places,
at Williston and East Goshen, turn into a true garnetiferous
schist. All the roads indicate its presence, but the best
exposures are along the creeks and railway cuts descending
to the valley.*
The South Valley Hill hydro-mica slates are therefore
not the York county hydro-mica slates of Dr. Frazer above
the Chiques quartzite, but the chloritic phyllites lying di-
rectly upon the Tocquan (Philadelphia) gneisses and mica
schists, and may in fact be the upward, continuation of C.
E. Hall's garnetiferous (Chestnut Hill) upper sub-division
of the Philadelphia series, f
The South Valley Hill belt holds so straight a course for
fifty miles from the Schuylkill into Lancaster county that
there can be no doubt of its extension to the Susquehanna
schist areas in York and Lancaster were easily distinguishable, both from
the less thoroughly metamorphic appearance of the latter, and from the fact
that the quartzite (Potsdam) generally came in between them. This was
generally true of the chlorite and underlying gneisses, though an isolated
patch of the former in the latter on the Lancaster county map (with no defi-
nite upper boundary) is frankly acknowledged in the text to be an attempt
at a lithological distinction run into a cul de sac, though abundantly justi-
fied and confirmed by a close study of the rocks in its strike in Chester
county. When Chester county was reached all sharply-defined boundaries
ceased to be possible. The quartzite faMed altogether on the southern side
of the valley, the mica schists became more gneissoid, the gneisses showed
chlorites, and the chlorites modified their distinctive character. Add to this
that a thin unknown series, representing the rotten representatives of all
these, has since appeared to increase the confusion. Nevertheless an at-
tempt was made to define on the Chester county map the chloritic masses
wherever the eye detected them, leaving an explanation of them for a future
task. The result however was to completely demonstrate the futility of
separating the chlorites from the mica schists in this area (Chester county.)
The area became dotted over with small and large masses of chlorites which
preserved no regularity in dip, strike, zone," etc. (Report C4, page 35.
Italicised by J. P. L.)
* Notes by C. E. Hall, published in Report on Chester Co., C4, page 60.
| Then the serpentine at the top of this sub-division (at Lafayette station
on the Schuylkill) would coincide with the serpentine at the bottom (or
south edge) of the North Valley Hill slates (south of Greentree, and west to
West Chester) and also with the serpentine of Lancaster along the south
edge of the Peach Bottom phyllite belt.
204 GEOLOGICAL SURVEY OF PENNSYLVANIA.
river twenty miles farther on ; and the county maps, in
spite of their inconsistent coloration,* when laid together
show that the straight forward continuation of the belt
brings it to the Susquehanna where the Peach Bottom phyl-
lites exhibit themselves for five miles in cross- section,
mostly vertical or on very steep dips, bnt complicated.
Prof. Rogers was therefore correct in calling the S.
Valley Hill schists Primal Lower slates ; and no doubt if
exposures allowed we could see them graduating down ward
into the upper schists and gneisses of western Chester and
southern Lancaster just as they seem to do across York
county, f
In spite of their general vertical or steep dips they are
undoubtedly closely and tightly crumpled into innumer-
able more or less parallel small anticlinals and synclinals,
upon a general floor of Philadelphia (Tocquan) newer
gneiss ; and that this floor participates in the crumpling is
proven by its frequent and sometimes abundant appearance
at the present surface along lines and over larger or smaller
areas of erosion from which the chlorite hydro-mica slates
have been removed.
Prof. Rogers was also correct in extending the South
Valley Hill belt of slates to the Susquehanna, although in
his final report he confined their identification chiefly to
the phyllite and hydro-mica slate region of middle York
county north of the Tocquan gneiss. That he identified
them also with Peach Bottom belt slates is evident from his
seeking there and, as he supposed, finding an outcrop of
Chiques quartzite, 90 feet thick, which he calls "its most
southern appearance in the state. "^
*For which I hold myself solely responsible.
f This view certainly simplifies the geology of our southeastern counties
but it is not wholly satisfactory, for it fails to explain the hornblendic gneiss
areas of Delaware county, leaving it an open question whether they are vol-
canic outflows, or anticlinal (or fault) uplifts of older sedimentary fully
crystallized rocks.
JGeol. Pa., 1858, I, p. 122, and special detailed description, page 189, which
I have inserted verbatim in chapter 16, page 183, above. It is a fine example
of the lucid and forcible style of the great geologist of Pennsylvania, the
closeness of his field observation, and the wealth of material facts to be
found in his immortal book. Would that he had been himself immortal,
and on earth to conduct the second geological survey of the state, and to
write this summary of it instead of myself.
IRON MINES IN THE PRIMAL UPPER SLATE. 205
CHAPTER XX.
Iron mines in the Primal upper slate.
Many of the first-class limonite (brown hematite) mines
of Pennsylvania are in Rogers' Primal Upper slates, over
the Chiques quartzite and under the Great Valley limestone.
Such are the Chestnut Hill mine back of Columbia in Lan-
caster, the Warwick (Jones) mine in the south corner of
Berks, the Trexler mine in Lehigh, the Old bank in Cum-
berland, and the Mont Alto banks in Franklin, and a
large number of other more or less important open mines
elsewhere ; some dating far back in the last century, and
others but a few years ; some abandoned if not exhausted,
others actively exploited at present whenever the iron in-
dustry is prosperous.*
It is not always easy to account for the vast quantities of
iron ore collected by nature at these mines. In some in-
stances the whole mass of slate seems to have been changed
into ore by a sort of chemical cookery ; the original slaty
stratification remaining visible, but in so wavy a state as to
suggest both a swelling and a settling of the mass against
the walls of a gigantic chaldron. f
In other cases the ore seems to be a sediment, with clay,
brought into a depression by inflowing waters which had
passed through the slate rocks and obtained by a leaching
process the iron which they contained ; the clay being a de-
composition of the felspathic body of the rock. The pot-
like mines of Cumberland and Franklin ranging along the
* Other similar and even more important mines not mentioned in this
chapter will be described in a future chapter, because they belong geograph-
ically to the belts of limestone outcrops, although geologically they originate
in the same way from the decomposition of slates of much the same kind,
but placed higher in the series of formations.
t See the pen and ink sketch of the Chestnut Hill mine face as it looked
forty years ago in Rogers' Geol. Pa. 1858, I, page 183, fig. 24.
206 GEOLOGICAL SURVEY OP PENNSYLVANIA.
foot of the South Mountain, ending with the Mont Alto
banks, are certainly of this character.*
The hydromica slates of York and Lancaster are not
uniform in aspect. The beds immediately beneath the
limestone are massive enough to make hills, like those
which line the Susquehanna from Wrightsville to Cabin
Branch run. Others of the series are disintegrated to a
dust of little glinting particles of mica. The more solid
beds contain innumerable beautifully perfect cubical crystals
of pyrites (sulphide of iron, and occasionally copper) or
the hollow casts from which such crystals have been dis-
solved out. Here we have one most evident and copious
source of brown hematite (limonite) iron ore.f
There are Cambrian argillites in Vermont which are simi-
larly studded with perfect cubes of pyrites. I have seen
50 on the side of a slab a foot square, most of them casts,
but some of the crystals projecting from the face of one
slab and leaving a cast in the face of the slab from which it
was split off. Their number was incalculably great. Sup-
posing the whole formation filled with them on an even
distribution there would be 67,500 in a cubic yard, and a
hundred thousand million of them in an outcrop a mile
long by 90' wide and 90' deep. As most of them were only
a tenth of an inch on a side, 27,000 would go to make a
cubic yard of solid pyrites, weighing say 2 tons of iron
and 2| of sulphur, and such a prism of country would hold
about a million and a half tons of iron. Usually, however.
*See my description of them in Proc. Amer. Pbilos. Soc. Jan. 3, 1873. But
these deposits, although on the outcrop of the slate, and deriving their birth
from it, are of a very late age. The same may be said of the great Hunting-
don county banks, formed in the same way and time from similar slates,
higher up in the series, interpolated among the great limestones. See my
Report to Lyon, Shorb <fe Co. ^1874), incorporated into the Reports of Pro-
gress in Huntingdon and Centre counties, T3, T4.
t Frazer, Amer. Philos. Soc. Dec. 4, 1885, page 40L When a boy, at Lafay-
ette's visit to Lancaster, I had given me a lot of these crystals which had
been picked from the bed of a stream. They were about the size of dice,
but varied on an edge up to an inch and down to the sixteenth of an inch ;
blackish-brown on the surface; when broken, a glittering gold within;
most of them absolutely perfect cubes, but some with imperfect corners,
not from recent fracture, for the defective corners had the same brown skin
as the sides.
IKON MINES IN THE PRIMAL UPPER SLATE. 207
the slates contain the iron in the form of ferrous oxide,
uncrystallized, and of percentages varying from 7 down to
less than 1. Even so the amount of iron held in the rock
is quite sufficient to account for great deposits of limonite
produced by erosion and oxidation in clays.*
The Chestnut Hill ore l>ank is 3 miles northeast of Co-
lumbia in Lancaster county, in a shallow synclinal (?) vale
on the south flank of Chiques ridge. f The ore is at the
bottom measures of the slate, next over the quartzite which
* Dr. Frazer discusses the origin of the limonite deposits in Report C,
1874, page 137, and thinks it most probable that it is to be lound in "the
pyrite crystals_of the brown slates. Even the slates which are not so situated
as to permit the percolation of water through them exhibit a porous
structure, the pores being filled with brown ochreous limonite ; and this
occurs to an unknown depth, and the slates seem to merge by imperceptible
degrees, in a direction normal to the plane bedding, first into completely
metasomatized pseudomorphs of limonite after pyrite (but still retaining
the form of the latter); then the same with a kernal of pyrite; then the
pyrite itself, first with a shell and then with a mere stain of ferric hydrate ;
and finally the same slates are revealed porphyritic from the pyrite, and not
at all decomposed." This suggests that the limonite was manufactured by
percolating waters in the body of the slate mass and merely set free by
erosion and gathered together into low grounds or cavities of the surface,
or caverns in the neighboring limestone, by running waters carrying the
mud of the triturated slates together with the limonite of the cavities as fast
as exposed, and both dumped together (slowly) into the reservoir to settle.
On page 139 Dr. Frazer makes his own calculation of quantity. A speci-
men of slate from under the York limestone taken on the railroad five miles
southeast of York, 3|"x2", showed to the naked eye 350 pits left by decayed
crystals of pyrites, varying from ^ to ^\ of an inch, or 40 to the square inch.
Nine layers of such pits were visible in the thickness of \ inch. This would
amount to 12.27 cubic inches of pyrites in a column one square inch five feet
long, or 32 pounds in five cubic feet of slate. Every running mile of outcrop
five feet thick and 1,000 feet high (eroded from the present surface) must
have yielded 75,000 tons of pyrites, or 48,700 tons of iron, or 80,000 tons of
limonite. He carries the calculation further on page 140, but the above is
enough to justify him in saying that allowing for all contingencies we have
more than enough to account for the largest ore banks.
f Dr. Frazer does not accept the simple synclinal structure. Ore beds at
mouth of a drift 250 long sink N. W. beneath the floor of the drift. In the
middle parts of the mine the ore's lie flat. One or more anticlinal waves are
therefore probable. On page 213 he makes a curious, novel, but by no means
useless, suggestion that possibly the weight of the high walls of the open
mine has helped to convert a shallow synclinal into a very low anticlinal.
His numerous close observations to settle the question of anticlinal wave
structure of the mass in this and the neighboring mine occupy several in-
structive pages of his book.
208 GEOLOGICAL SURVEY OF PENNSYLVANIA.
has been exposed in the mine floor. The dips are gentle;
bottom flat; an open quarry, 100 feet deep, ore from top to
bottom of the slope walls; area in 1856, about 11 acres, in
1877, 1400' wide by 3350' long. The old Grubb mine half a
mile east is in the same slate and merely a continuation of
the formation towards Lancaster.*
The decomposition of the slate mass into limonite is evi-
dent to the eye. The upper half or more of the walls are
of a bluish, yellowish and white greasy clay, laminated as
it was before the change. Underneath is a mass of solid
ore, 10 to 30 feet deep, lying on the quartzite floor; brown,
cellular fibrous hematite (limonite) precipitated from above
as the heavier element of the wet clay which filled the hollow.
The present drainage passed beneath the slate over the face
of the quartzite ; and this has always been the agent of de-
composition. Layers of such ore however occur in the slates
above, resting on tight clay strata which formed subordinate
drainage planes. In only one place was the ore changed to
magnetite; a band from one to three inches thick is full of
beautiful small octahedral crystals of magnetic iron ore.
Dr. Frazer says that the general appearance of the Chest-
nut Hill mine is that of all the banks of York county along
the slate belt, but on a much larger scale; the ores being
in all of them of two kinds : (1) Wash ore, distributed
through the upper part in planes but without the regular-
ity of a bed of sediment, i. e. concretionary shot, balls and
chuncks embedded along rude planes of clay ; (2) Solid
concretionary ore, usually low in the mine, hard, massive,
usually darker and more botryoidal or bunched like grapes.
Quartz fragments are seen sticking out of the slope walls.
*"A11 the ores which lie above the Chikis quartzite from the mouth of the
Chikiswalunga through Silver Spring and to the German settlement and the
works of the New York Company should be included are parts of the same
system." Frazer, Report C3, p. 203. The. /Shirk bank is north of Chikis
ridge 3 miles N. of Columbia and E. of Marietta. It produced 8000 tons a
year for ten years, afterwards less ; at first 4 tons of ore to one of wash, later
1 ton of ore to four of wash. It was an exceptionally rich pot, very wet,
slate clay mass, required heavy timbering. No quartzite seen. Limestone
exposed in the wall. Grade of ore 40% to 48%. Stopped 1874. Coppen-
hoffer's and Garber'sare small banks along the same north foot of Chiques
ridge, following the fault.
IRON MINES IN THE PRIMAL UPPER SLATE. 209
Hollow bombs of ore, sometimes tilled with very soft fine
clay or simply with water and lined inside with black oxide
of iron,* are common.
Until the introduction of the Lake Superior Marquette
and other red hematite ores Pennsylvania easily held its
preeminence as the great iron smelting state of America
by reason of the great number and remarkable size of its
brown 1 hematite (limonite) iron deposits ; and by importing
the richer magnetic and specular ores for mixing with its
own stock of limonite and fossil iron ore it still re-mains
the principal iron state, furnishing always about one-half
of all the iron produced in the United States. She was the
first to adopt Bessemer' s process of making low steel in 2,
and afterward 5 and 10 ton flasks, f
Most of the great limonite beds are, as has been said
above, in the Upper Primal slates. Others are in the lime
slates above the Trenton limestone No. lie. Others are in
the slates interbedded in the great limestones. Others are in
the slates over the Oriskany sandstone No. VII. These
will be described in their proper places.
The Upper Primal Slate limoidtes range along the
north side of the Chester county valley ; along the hydro-
mica belt in York and Lancaster; along the north foot of
the Highlands from Easton to Reading, and along the north-
west foot of the South Mountains from Boiling Springs to
Mont Alto. It is probable that this is also the geological
horizon of Pine Grove mines on Mountain creek in the
heart of the South Mountains ; and possibly of the Rich-
mond ore bank in Path Valley north of Mercersburg in
Franklin county, although this last range is along the
*This lining is often oxide of manganese, a metal constantly accompanying
iron in limonite deposits ; often beautifully crystallized in fibers or needles.
The bombs and balls show plainly enough that the peroxide of iron was dis-
tributed as fine particles throughout the plastic clay, and that these particles
slowly concentrated around points of mutual attraction, probably in most
cases towards minute quantities of organic matter which have disappeared
by oxidation.
f A process virtually invented and practiced by Wm. Kelly at his furnace
in Kentucky, when he boldly blew air into the molten metal in his furnace
hearth. See my Iron Manufacturers' Guide, 1858.
14
210 GEOLOGICAL SURVEY OF PENNSYLVANIA .
Path Valley fault, on the contact of the limestone with the
Hudson River slates ; as described in a future chapter.
Chester valley Umonite mines.
The mines of the Chester county valley have never been
of first-class importance. Prof. Rogers' description of them
in 1858 was condensed and re-published in C4, 1883, pages
141, etc. It has hardly more than a historical value, since the
change in the iron industry has concentrated the iron works
and destroyed local small mining by the importation of dis-
tant richer ores. But it has a geological value for those
who study our formations.
Some of the old banks are on the edge of the valley, and
evidently in the Upper Primal slates, above the sandstone
and beneath the limestone. Others are as evidently wash-
ings from these iron-bearing slates into ancient caverns in
the limestone, the roofs of which have been removed by
erosion, leaving great pots of clay filled with wash and ball
ore. Of this kind are the deserted
Hitner banks near Marble Hall, Montgomery county r
from one of which were taken 10,000 tons in 1852, and
12,000 in 1853. From all the pits dug east of the Schuylkill
up to 1858 probably 60,000 tons were taken, in a belt seven
miles long and a mile wide. The ore deposits ranged in
long narrow strips, as deep troughs of iron soil sunk in the
limestone outcrop ; the two most productive being one just
north of the Barren Hill range ; the other just north of the
belt of marble. But outliers were found ; as, Wood's pit,
one mile north of Marble Hall, where shallow ore soil rested
on limestone so thin that the North Valley Hill sandstone
was struck beneath it.f
West of the SchuylTcill several pits were made south of
Bethel Hill (Whitehall's pit, Fisher's pit) for Merion fur-
nace use.
The Baptist Church old shaft, 75' deep, got superior ore,
resting on white marble. Another pit was sunk 200' feet
further east.
t See C. E. Hall's Report, C. 6.
CHESTER VALLEY LIMONITE BANKS. 211
Fisher (Geo.) bank, 300' N. E. of Henderson's marble
quarry in U. Merion, is large, and until 1854 yielded good
ore ; afterwards more of an earthy wash ore. Another pit,
1250' N. E. of the last, and a later pit for the Phoanixville
works gave $ ore.
Widdart's bank, 800' S. of last, was reopened before
1854. Millerton's bank near the school house sent ore to
Jones' furnace above Conshohockin. Otto's bank, newly
opened in 1854, had ore. Supple' s & Hampton's pits
were small. Hughes & Jones' 1 pits were also small, but
made a large group.
Howellville, Tref. town, had its group of pits from which
good ore was got. Wilson's, N. W. of village. Wood-
man'' s had ore f, dirt ; sent to Phcenixville. Jones',
Beavers' , & Bucks and King's, near the Baptist Church
m. from Centreville, were all three large banks. 8. Bea-
ver's bank, mile S. E. of head of Valley Forge dam, lay
along the north side of the valley, and got its ore-wash
(Rogers thought) from the lower magnesian part of the
great limestone formation. Holland' s bank, 1 m. N. W.
of Howellville, 43' deep in 1854, sent excellent ore to Pho3-
nixville.
West of Paoli was another group of diggings : Buchan-
an's, 1200' N. of Oakland hotel, f ore, sent to Jones' fur-
nace. Jacobs' , 2 m. E. of Oakland, and two others m. S.
of Ship tavern. McGuire' s, 1 m. N. of tavern ; much good
ore. E cans' , f m. E. of tavern; much good ore. Neat's
three pits.
An untried pit was opened 1 m. N. W. of Downingtown.
West of Coatesville several small pits on the south side
of the valley.*
York county Umonite banks.
The mines of York and Adams county in the hydromica
(Upper Primal) belt are described by Prof. Frazer in his
* Rogers' Geol. Pa. 1858, pp. 217 to 219, gives some very interesting details
of Lancaster Co. limonite banks in evidence of his belief that the South
Valley Hill mica slates (bearing iron) underlie the Chester Valley limestone
formation.
212 GEOLOGICAL SURVEY OF PENNSYLVANIA.
Report of Progress C, 1876. On pp. 5 to 9 is given a list of
158 mines in all the formations of the two counties, in alpha-
betical order, many of them small openings, others old, large
and deep mines.*
Golin bank (67) 2 miles W. of Wrightsville, at the N.
edge of limestone belt, S. edge of slate belt ; opened 1854 ;
in 1874, 400' long, 25' deep at west end, in sandy clays;
B. StricJcler bank. 1 mile west of the Gohn, on the same
line ; 1854 ; worked by Mnsselman ; then by Haldeman till
1864 ; 1874 abandoned ; half an acre ; 30' deep to water.
Stoner bank, half a mile further west on same line ; 1850
to 1873, 40,750 tons to Musselman and Watts ; partly by
shafts ; open f acre, 25' deep.
D. Rudy 's banks, half a mile further west on same line ;
1862 to 1870, 9,872 tons ; H acres, 25' deep ; abandoned.
Ruby 1 s bank, half a mile (4 m. from Wrightsville) on
same line ; 1862 ; worked 4 years ; 400' long E. and W. or
% acre ; abandoned ; much loose qnartzite.
Keller's bank, half a mile further west; acre ; 10' to
water ; ore exhausted.
Heistand's bank, a mile further west on same (midway
between Wrightsville and York ;) 1864 ; Musselman &
Haldeman ; 2 acres, 600' long, 20' deep to water ; abandoned
1871 ; walls, clay and gravel.
Blessingef s bank, one mile further west ; and 1000' N.
of limestone limit; acre; trench 750' E. and W. ; exhausted;
sandstone fragments and sandy slate.
Norses bank, half mile further west, and J m. N. of
limestone ; f acre, 300' long, 25' deep ; abandoned.
Miller's bank, one-third mile further west, and 2000' N.
of limestone ; i acre, 15' deep ; has only yielded 300 tons ;
ground strewn with sandstone and slate blocks.
* Of these are described 126, arranged in nine lines running N. E. and S.
W. and numbered from N. E. to S. W. Nos. 1 to 6, from Shrewsberry to the
Maryland line ; 7 to 14, S. of Margaretta furnace, from Red Lion to 8. of
Jefferson and Loganville to Red Lion ; 15 to 66, from S. of Wrightsville by
Hanover Junction to Littlestown in Adams ; 67 to 109, from Wrightsville
through York to N. of Hanover in Adams ; 111 to 118, a group north of York ;
110, near the river N. of Wrightsville ; 119, 120, S. of Wellsville ; 121, W. of
Wellsville : 122 to 126, near Dillsburg. In this chapter only those in the
hydromica slate belts will be noticed.
YORK COUNTY LIMONITE BANKS. 213
S. and 1. Deitz's two banks, m. apart, further on, 1500'
N. of limestone ; about 1864 ; abandoned 1870 ; yielded 2000
tons ; 8' stripping over ore lying in pockets in white and
yellow clay ; in all \ acre, 20 ' deep ; water scarce.
Susanna Fritz' s bank, a mile west of Norse bank (.or 3
m. east of York) and \ m. N. of limestone border ; 1865, to
June, 1874 ; principally wash ore, in pockets and nests in
blue clay which prevailed in the walls beneath the strip-
pings ; abandoned, but large quantity of ore at north end
reaching nearly to the surface ; 40' deep, partially filled
with water (1874.)*
HeidelsbacTi 's bank, f mile further west and 500' north
of the limestone ; small ; 600 tons ; exhausted by 1868 ;
acre, 10' deep.f
Ifibert banks, If miles north of York (the most northern
is sometimes called the Corr bank). Operated by Benson
& Cottrell, owners from 1866 to October, 1873 ; |+1| acres,
30' deep ; principally wash ore ; 10 tons daily ; part filled
with water (1874)4
D. Louck's banks, li miles northeast of York and ^
mile north of limestone ; two, 100' apart, with a smaller
bank between ; 1867 ; wash ore, some lump ; water not
quite sufficient to wash ; acre, 20' deep, and acre, 25'
deep.g
Thus far the limonite deposits have been either on or just
N. of the northern edge of York Valley limestone belt,
which edge crosses the Codorus a mile north of York,
swings west and north and east to recross the creek two
miles lower down, and recrosses a third time 5 miles north
* Many samples taken for analysis yielded in McCreath's laboratory :
Insol. res. 19.750; iron sesquiox., 63.285 ; alum. 0.765 ; manganese sesquoix.,
2.210; phos. acid, 2.986; sulph. acid, 0.068; lime, 0.196; mag., 0.216; water,
10.880=metaljic iron, 44.300; inang., 1.540; sulp., 0.024; phos., 1.303.
f Here a compact bed of quartzite crosses the road, dipping 60 northwest,
but there is room for concealed southeast dips between it and the limestone
belt.
J An interesting bed of compact quartzite, dipping 30, north 15 west cuts
out the ore in the Corr bank. Slates carrying ore much contorted, with
cleavage planes dipping 70 southeast If these be original bed planes then
the slates dip beneath the limestone.
Rock beds cut are crystalline schists much intersected by veins of quartz.
214 GEOLOGICAL SURVEY OF PENNSYLVANIA.
of York. From this third crossing the limestone edge runs
west 2f miles to Ewingsville, and so keeps on to the north
side of the Pigeon hills. It then returns east, south, south-
west around the south foot of the hills and runs on into
Adams county.
Returning now to the Codorus creek there are several
banks in the slate country north of York: Lightner's,
Louck's, Benson & Cottrell's, Hake's, west of the Codorus ;
and Benson & Cottrell's and Smyser's east of the Codorus ;
all of them either on the limestone border or not more than
1500' from it. Taking them in the order named will be to
follow the edge of the limestone around Pleasureville. (See
Report C, 1875, p. 69.)
Banks north of York.
Lightness bank, 1 m. W. N. W. of York, on the lime-
stone border; leased by an English company, Sept., 1874.
LoucTc 1 s bank, If m. N. of York, \ m. from the limestone;
open cut 60' long, 15' wide, 18' deep in bluish clay; stripping
5'; yellow clay with ocreous iron, 7'; white clay and chlorite,
thin; clay and ball ore V; dip of slate 46 N. 23 W.; dip
of ore the same.
Benson and CottreWs bank, near last; 1870; 1000 tons a
year; ten per cent, lump; water scarce; ore contains a little
sulphur and a little phosphorus; magnetic sand and much
specular iron intermixed with the ore.
Hake's bank, % m. N. of last; clay; not at work in 1874.
Smyser'sbank (SmaW s bank), 3 miles N. of York, on
the south edge of the limestone a mile N. of PleasureviJle;
leased for 20 years (1864-1884) by Ashland Iron Co. 2
acres, 40' walls; 15 tons per day of both wash and lump
ore of two kinds, one a sandy manganese limonite; the other
a smooth greyish blue compact ore full of small cavities
stained on the edges with limonite; also a white ore looking
like a cherty limestone, in fact a spathic or carbonate iron
ore, suggesting interesting reflections upon the genesis of
the limonites. There is on the east side of the bank a lime-
stone bed which dips 18 to the west, i. e under the ore de-
BANKS NORTH OF YORK. 215
posit, and Dr. Frazer suspects it of a greater antiquity than
the York valley limestone. (See C, p. 68.)*
Cottrell & Benson 1 s bank, across the road from Smyser's
bank ; 1871 ; 10 tons per day, all wash ore, hauled to
Emigsville, railroad to Marietta. In 1874 acre, 40' deep.
(C, p. 66.)
Banks west of York.
Eisenhart(Jac.}, on the Gettysburg turnpike, 2 m.W. of
York, has surface wash ore on slate ground ; and not far
from here near the Carlisle road fork to Emig's Mill in the
debris of an old pit was seen a large specimen of magnetic
limonite. The Beelor trap dyke runs across the neighbor-
hood towards the old
Kauffman bank, 3 m. S. W. of York on the narrow belt
of slate which from here west to Pigeon hills splits the
limestone belt into two ; 300 tons were taken out ; ore so
magnetic as to disturb the surveyor's compass ; ore, mostly
anhydrous, lay in scales along with mottled red and blue
limestone ; a mass of ore in place dips 25 S. 10 E. ; but
the associated slates dip 70 S. 10 E. Beelor' s trap dyke
runs close by on the east.
Ey ester s (M.}~bank(Smysers's, Brillinger 's 3 m. further
S. W. along the N. W. edge of the slate belt, along aban-
done<J trench 350' long, 20' deep ; in fine-grained mica
slates dipping 64 S. 20 E.f Ore in nests and lumps of
brown and red hematite, but no magnetic visible under the
lens ; slates almost all weathered into white clay, with
* Careful sampling, and analyzing by A. S. McCreath, gives the following
constitution of the first kind of ore : Insoluble silicious residue, 14.78 ; iron
sesq., 46.28; alumina, 2.67 ; manganese sesq., 22.89; phos. acid, 1.49; baryta,
1.32; lime, 0.24; magnesia, 0. 15 ; water, 11.20 ;=Iron, 32.40; manganese,
15.93; sulphur, 0.03 ; phosphorus, 0.65. Cold short; and unlike any other
ore as yet found in York county. The Spathic ore, analyzed by A. Pearce,
under Dr. Genth yielded; ferrous carbonate, 77.99; mang. carb., 0.45;
magnes. carb., 3.53; calc. carb., 1.43; alum., 2.81 ; sil., 11.56; water, organic
matter and loss 2.23 ;=iron, 37.65.
f All the dips, slate and limestone in this neighborhood are steep S. E.
(See ore map of survey on a large scale, with all the dips marked, in Re-
port C. ) If the slate belt be an anticlinal, then the dips next to the northern
limestone belt must be overturned, and the slates at this mine although
seemingly over the limestone are really under it, where they ought to be.
216 GEOLOGICAL SURVEY OF PENNSYLVANIA.
streaks of irony clay ; what is not shows rotten lamination;
at northern end of pit compact fine-grained mica slate, over
which at the south end are 100' of the soft clay strata
carrying the ore.
Emig 's (Sam.) bank, 3 m. W. of New Salem, near Nash-
ville, near S. edge of slate ; opened 1872.
Johnson's (W. S.) pit, I m. W. of last ; 1873; ore.
Mengis' (And.) bank, 1 m. S. of last, near N. edge of
southern belt of limestone ; 1872 to 1874, 3,772 tons.*
Banks of the Pigeon Hills.
Myers' (Mich.) a mile west of last, 1873. Roth's (S.) a
mile north of last ; 1873 ; 10' deep ; ore. Roth's (&) I m.
S. by W. of last ; 20' deep ; 7' stripping. These are a
group in the slate belt. Miller's (J. L.) f m. S. W. of
last; abandoned. Bechtel' s (Geo.) If m. S. W. of Myers' ;
opened about 1868 by Musselman & Watts ; abandoned in
1873.^Forry (G.) reports ore in mass in his orchard near
the limestone, 5 m. N. E. of Hanover. Boyer' s (Sam.)
bank, % m. west of last ; 1854 ; leased 1872 ; acre, another
1 acre, both 15' deep ; ores In segregated shelly, friable
masses in clays ; no unaltered slates seen. It is the first
of a series of closely neighboring pits marking the northern
edge of the slate belt leaning against the Pigeon Hills and
running on to the Adams Iine4
Moulk's (S.) bank, 5 m. N. E. of Hanover ; 1859 ; in 1870-
1874 the Leesport Iron Co. took out 14 tons a day; incline
plane 200' long.
* Watts & Sons, the owners, give these figures and an analysis : Iron,
39.640; insoluble, 37.800; sulphur, a trace; phosphorus, 0.080; undeter-
mined, 22.380.
t These last eight banks are disposed around one of the southern spurs of
the Pigeon Hills and mark th*e shape of the spur. (Frazer in C, 55.)
Jit must be kept in view that this slate belt keeps the limestone belt (to
the south of it) away from the Chiques quartzite mass of the Pigeon Hills ;
therefore beneath the limestone.
One hundred and eighty to one hundred and eighty-five car loads per
day (14 tons) worth $2.50 per ton at Kauffman's siding on Hanover Branch
RR., 3 miles distant. One hundred-paddle lump washer and sand washer ;
35 horse power engine consuming 1100 pounds coal ; 19 men in three gangs ;
f 1.00 per day wages ; or f 1.50 if paid 7 to ~l\ cents per car load ; engineer, |33
PIGEON HILLS BANKS. 217
MouVs (Sol.} bank, % m. west of last ; 1854 ; 2 acres, 15'
deep ; tenaceous clay under stripping ; engine house at N.
E. end ; idle in 1874.
MouC s (P.) banks, (two,) small.
BechteVs banks ; (I) 4 acres ; (2) J acre.
Haldeman & Co.'s bank; near the last ; 1870 ; acre ; 8'
stripping ; -f wash ore in yellow and blue clays ; ore bands
V to 3' thick irregularly running out ; used at Chiques to
mix with Cornwall ore ; 25 tons per day ; pit 45' deep ; water
supply deficient. Analysis: Iron 43.00 ; manganese 3.88;
sulphur 0.09 ; phosporus 0.67.*
Miller' s (Ashland Co's) bank, 400' W. of Kaufman's (3
m. N. N. E. of Hanover) and at the base of the Pigeon Hills;
1863; 3i acres; 15 men; 18 tons per day without incline plane;
all the blue and yellow clay mass contains paying mass ore;
mixed with tremonium ores in the Ashland furnace. Ban-
man's bank, not far west of last; \ acre; stopped 1873.
Miller ( Widow) bank, near last, small. Porter (Gov.) bank;
1840 to 1862; shut; 1 acre. GUI's bank-, several pits in
quartzite and sandy slates, 3 m. N. of Hanover; much ore;
abandoned. f
Banks near Hanover.
' The above-described banks are ranged along the foot of
the Pigeon hills north of the York limestone belt. South
of the limestone there is no such range of banks in the
hydromica slate country ; but there are four at Hanover,
and two four miles northeast of Hanover of considerable
per month ; foreman $40 ; 11 working hours ; 400 tons a month extracted ;
two 35 horse-power boilers ; 5 cars in use ; water for washer pumped from
mine ; 12 tons of ore per day washed ; transport to siding 60 cents per ton,
contract wagons belonging to contractor ; 9 men always mining ; stripping
9' ; under this white clay and gravel ; then j^ellow ore clay, no bottom yet.
(Report 3, 1874, p. 59, here quoted as specimen of its statistics.)
* See full analysis in C, p. 61. A. plate of " red oxide " runs S. W. towards
Kauffman's; analysis: Iron sesq., 72.14; alumina, 1.72; manganese sesq.,
0.39 ; phos. acid, 0.43 ; sulp. acid, 0.12 ; lime, 0.17 ; magnesia, 0.33 ; water, 5.76 ;
insol. sil. residue, 19.09 ;=Iron, 50.50. This tough, hard siliceous kind of ore
is found elsewhere in the county. Kaufman's bank, next the last, started
1874.
fMcConaughy's exploitation pits in quartzite, 3^ m. N. W. of Hanover,
1874, has begun to show fairly. ThiS'nds the series westward.
218 GEOLOGICAL SURVEY OF PENNSYLVANIA.
importance. The four just south of the village of Hanover,
a mile from the Adams line, are
Baumann (/".) pit, first opened a century ago ; reopened
1860 ; then leased by the Wrights ville I. Co., who took out
1000 tons. Flickinger' s, 300' west of last; 500 tons got.
Delone (Louis] bank, i mile W. of Baltimore pike ; 1867 ;
2000 tons got in six months, large and small lump ore in
slate mouldered to clay; slight stripping; large body of
ore seen (1873) in northeast heading.* Forney (A. M.)
bank, 400 yards west of last ; 1863 ; 3500 tons got and more
in sight, in hole 200' long by 20' deep ; ore lumps in clay ;
abandoned.
The two important limonite mines on the south edge of
the limestone 4 miles N. E. of Hanover, are the well-known
Dollinger and Sprenkel banks :
Dollinger (J. and D. ) bank, leased by the Leesport I. Co.
and opened in 1873 ; 180 car-loads a day ; 90 per cent wash
ore; lumps and nests in the clay of the decomposed slate
formation.t
Spr entile* s shafts ; m. N. E. of last ; sunk 1874, north
of H. & Y. S. L. RR. Ore in first shaft peculiar, dull brick
red, containing masses of specular and some micaceous ore,
much mixed with sand and the slate gangue (a fine-grained
chlorite hydromica slate with thin intercalations of lime-
stone}. Two veins struck by the shaft, upper one V thick,
with a thin roof of slaty limestone. The N. W. shaft takes
out ordinary limonite. Prevailing dip, 50 N. W. as if
going under the valley limestone. Further west, Mussel-
man shaft struck solid ore.
In quarry 500' N. of first shaft limestone and slate con-
tact seen, dip of both 48 N. 35 W., slate under limestone.
This is an all-important geological fact, establishing
* Analysis: Iron, 33.5; *sulp., 0; phos., 1.47; silica, 23; alum., 27.3; ox.
org., loss, 14.7. Another: Sil., 8.2; ferric ox., 70.1; alum., .96; mang. ox.,
1.75; phos. acid, 2.54; sulp., .03; water, lB.15;=iron. 49; mang., 1.21; phos.
1.11. Another by F. A. Genth : Sil., 7.55; ferr. ox., 65.6; alum., 2. 05; mang.,
ox., 7.29; ph. acid, H.05; water, 13.88; mag., .35; cobaltic oxide, 0.22 ;=iron,
45.9; manganese, 5.07; phosphorus, 1.33. (Report C, 1874, p. 41.)
fSee statistics in C, p. 55 ; and analysis : Iron 45. 1 ; manganese, 1.5 ; sulp.,
0.09 ; phos., 0.60.
SOUTH OF THE YORK VALLEY LIMESTONE. 219
the location of the ore in the Primal Upper Slate 'be-
neath the Silurian (Ordomcian} limestone, although the
nearest quartette is a mile southeast from the ore.^
Banks south of the York Valley limestone.
Before continuing this list of mines into Adams county,
we will return to the Susquehanna, and note the ore banks
of the hydromica slate belt south of the York valley lime-
stone, beginning with the one nearest the river, No. 15 on
the York county map, C, page 16.
Wilton's ~baiik, l^m. S. of Wrightsville; 1850; 1855; 1858;
12,000 tons; abandoned before 1874, but much ore remaining
65' beneath the surface, in a ravine between high slate hills;
limestone seen up the ravine; quartzite marked on map.
Leber (Dan.} bank, 2 m. S. of last, m. back from the
river, on the edge of the limestone; 1872; mostly lump ore,
concentric bombs, the shells separated by shells of clay:
limestone 1000' S. 15 W. of the pit dips 40 S. 22 E.,
therefore the north lip of Cabin Branch Run synclinal lime-
stone basin has the ore slates underlying the limestone.
Emig (J.) bank No. 1, 600' W. 30 W. of last, on the edge
of the limestone; stopped 1867.
Emig (J.) bank No. 2, m. W. of last, very old, aband-
oned 1869; shaft 110' deep; bottom ore so compact as to re-
quire blasting; very little wash ore, mostly lump.
'Keller (Geo.) shafts, 1 m. W. of last, (4 m. S. of Wrights-
ville); about 1864; 70' and 30' deep; almost all lump, re-
quiring blasting, very near surface; in hydromica slate
partly in a very sandy slate; many pieces of quartzite;
much of the ore magnetic; very crystalline limestone close
by, dipping 54 S. 22 E.
Burg (Reuben) bank, at Prospect (Furnace P. O.) li m.
from Margaretta Furnace; shaft 30' deep struck limonite
charged with magnetic particles.
Small (J.) bank, ^ m. W. of last; same black ore; lump
and wash ore equal; makes foundry iron.
Margaretta Furnace banks, on Cabin Branch Run, 3 m.
t See the York Co. map published in Atlas to Report C3 on Lancaster
county.
220 GEOLOGICAL SURVEY OF PENNSYLVANIA.
from river; Slay maker sold (1850) to Halm and Himes, who
worked them 1867 to 1874 (date of Report) at 200 tons per
week; various limonites (lurgite, &c.,) brittle, sandy, shelly
grading off into slate rock; the purest (" black ore ") ana-
lyzing 60 iron seems to have been subsequently deposited
in cavities between the mica sla^e strata, too much decom-
posed to show true dip; mines on the contact of slate and
limestone.*
A mile S. of Margaretta furnace are two banks: Jas. Cur-
rarfs, opened about 1844 and W. G. Case's, about 1851, from
which ore has been mined, but they have long lain idle.
Keller (/.) bank, If W. of Margaretta Furnace; 1866;
JOOO tons the fir,st six months ; then abandoned ; ferrugi-
nous slates dip 70, S. 20 E. . This bank is within a short
distance of the edge of the phyllite belt, therefore near the
bottom of the hydromicas.
Barcoft s (Butcher's] bank, 500' west of last and higher
in the same hydromica belt ; opened 1840 ; work suspended
in 1868 ; ore cold short, plate-like, hard, flinty, tough, with
unusual amount of black glassy coating, and mamillary
stalactites, knobs and ridges, which when broken show
cross-fiber crystallization (gothite). Large masses of lump
ore in the clay, regularly arranged ; one massive lens dipping
30, N. 80 E. through the slates, which are more or less
completely changed to clay ; upper part of mine limonite
and turgite. Musselman & Watts took out 10,000 tons at
one time.f
Banks in the York county pJiyllite belt.
Barley bank, 1 m. W. of last ; 1868 ; 400 tons in two
years ; dark brown hematite in clay, in phyllite slate belt ;
i m. from quart zite belt.
Hengst bank, 900' S. of W. of last ; in same phyllite belt
*See mining statistics, p. 20. Result of analysis of shell ore: iron, 48.8 ;
manganese, 0.79 ; sulphur, 0.038 ; phosphorus, 0.343.
fSee mining statistics in C, p. 22 ; and Watts' analysis : Silica, 26.75 ; perox.
iron, 47.15 ; alum., 1.70, water, 11.40; undetermined, 13.00 ;=Iron, 33.00. A
low grade ore if this analysis represents the mine ; but its siliceous character
is due to its place in the phyllite formation instead of in the upper hydro-
mica formation.
BANKS IN THE YORK CO. PHYLLITE BELT. 221
and as near the quartzite ; 3,000 tons in three years, 1868 to
1871 ; then idle ; 15' deep ; ore a conglomerate of ball ore
and ferruginous slate.
Moser's new bank, 3 m. S. W., of last, 2 m S. E. of Longs-
town, 2 m. N. of Dallastown, 1 m. from edge of hydromica
belt ; 1865 ; abandoned ; poor ore.
Ensminger* s banks, 10W and 1700' S. W. of last ; 1866 ;
1873.
Moseys old bank, 1 m. W. of last, \ m. W. of Peach
Bottom RR. near edge of hydromica belt ; 1820-f- worked by
York Furnace Co. ; then J. A. Wright & Co.; then (1850)
Shoenberger, Musselman & Co.; then Musselman & Watts ;
then Musselman & Sons ; 42,090 tons from 1850 to 1873 ; ex-
cavation 250 yards long, now abandoned ; ore masses are
still visible in yellow, white' and blue clays ; bottom strewn
with lean compact ore ; lump and wash ore equal.*
Williams' oldbanks (GladfeUer" 1 s), 2m. E.N.E. of Logans-
ville, was not worked after about 1830, but an immense
amount of ore must have been taken from the numerous
extensive deep excavations in the phyllite belt within about
a mile of the hypothetical limit of the Tocquan schist belt.
BrillliarV s bank, 1 m. E. N. E. of Logansville, has been
worked by Kaufman for Columbia furnace, and yielded
the same ores as the next.
Feigley bank, the S. W. continuation of the last, opened
by Musselman in 1867 ; up to 1874 (date of report) yielded
50,000 tons of limonite, finely disseminated through clay
at least 40' deep ; 10 per cent lump, 90 per cent wash ;
also a dark-blue compact heavy clay ore ; also a peculiar
"honey-comb ore," composed of minute plates of limonite
knit together like paper walls of a wasp's nest.f
Moser's oldest bank, 200' W. of last.
*See statistics in C, p. 24. One specimen was of parallel flat plates, united
by one or other edge, space filled with lepidocrocite, stalactitic limonite and
turgite. Another was botryoidal coated with black glossy turgite (?). A
third was compact brown limonite. A fourth (50 pounds) showed all these,
and also a peculiar separated structure, the ridges being an inch high uni-
formally covered with glossy ore. Partial analysis is (Watts) : Iron, 40:
silica, 32; phos., 1.17; water, 8.
t For statistics of mining see C, page 14, J. B. Britton's analysis of an
average sample : Iron, 46.08 ; ox. 19.74; insol. sil. res., 18.66 ; water and org.
222 GEOLOGICAL SURVEY OF PENNSYLVANIA.
Banks in the Jiydromica belt south of York.
Leader's Hill old opening, f m. W. of New Paradise;
slates dip 84, S. 70 E. No ore showing.
Hess bank, 5 m. S. of York, 2 m. W. of Logansville ;
150' long, 15' deep ; 1868 ; ore too sandy; slates asbestiform,
vertical, strike N. 20 E.
Falkenstine shaft, abandoned.
Meyer's (B.) bank, 1200' N. W. of Gladfelter's railroad
station ; lean ore in vertical slate striking N. 30 E.
Stambach's shaft, m. W. of station ; in dark slates
holding crystals of micaceous and magnetic ore.
Gladfelter's bank, f m. W. of station, 10' deep in verti-
cal slates, striking N. 34 E.
Geisselman' s bank, J m. W. of railroad between Glad-
felter's and Seven Valley (Smyser's) stations; four small
shafts sunk 1870, in hydromica slates impregnated with
iron oxide.
Thomas Iron Co.'s banks, $ m. S. W. of Smyser's rail-
road station ; two banks and three shafts, acre and f acre,
engine house, drifts, etc.*
Walters- bank, f m. N. of W. of Hanover Junction rail-
road station ; 1872 ; much hard limonite still visible in
bunches in clay of decomposed coarse-grained slate ; f acre,
40' deep.
Crout' s bank, ^ m. N. E. of Strickhauser's station, Han.
Br. RB,., 800' along the road, 18' deep ; hard, compact
sandy limonite ; sometimes operated.
Knotwell's shaft on the York I. Co.'s hill ; Aug. 1874,
had reached hard ore (at 27') same as York Co.'s ore.
mat., 10.94; sulphur, none; phosphorus, 0.69; alum., 1.92; lime, 0.17; mag-
nesia, 0.56; manganese, 0.33 ; undetermined, 0.91.
A finely laminated bluish limestone containing white crystalline lime-
stone scattered through it in spots resembling in certain portions a calcareous
conglomerate, in others simply mottled, appears in both banks, and in the
run, dips 85, N. 20 W. In a quarry' near by it is so mixed with crystalline
hydromica flakes as to mimic hydromica schist, although containing 78 per
cent of carb. lime and magnesia; thickness perhaps 400'. This is an im-
portant observation. (C, p. 15.)
* Statistics in C, p. 27. Analysis : Iron, 51.7 ; no sulphur ; phos., 0.052 ; sil. ,
6.0; alum., 16.4, etc.
BANKS IN THE HYDROMICA BELT S. OF YORK. 228
Strickhouser's shaft, 1,200' W. of last; 1860; pit 200'
long (N. 39 E.) 30' wide and 10' deep, has shaft in middle
10' deeper.
KnotweWs bank, 1600' N. of York Co.'s works; 200'
long ; dip 66, S. 82 E ; another slate exposure strikes N.
20 E.
York Iron Co.'s mine, the most widely known bank in
York county, yielding the so called "Codorus ore," 2 m.
N. E. of Jefferson (Codorus P. O.), mile N. W. of the
RR. ; opened by Musselman in 1854 ; worked almost con-
tinuously from 1861 to 1874 (date of report) by York I.
Co. ; a hard, compact slate highly charged with micaceous
and some magnetic ore ; 10 to 20 tons a day. The slates in
Strickhouser's ravine through a ridge 100' high stand
vertical. The back bone of the ridge is Chiques quartzite.*
Sheaffer' s pit, % m. S. of last ; 1867 ; 350 tons; exhausted.
Thomas Iron Co.'s old pit, 1700' S. W. of last; 1869;
worked one year and abandoned.
Thomas, Iron Co.'' s No. 2, two banks and a shaft, 2700' S.
E. of last ; 1869 ; 30' deep, abandoned ; layers of mica slate
between ore deposits ; dips 45 to 90, N. 45 W.
Thomas Iron Co.'s, No. 3, pits along a 100' line S. 30 W ;
outcrops of mica slate further west dip 75, N. 25 W.
Smyser (E. O.} bank,' 1869 ; acre, 15' deep ; idle.
Hanover Branch RR. open cut yielded considerable ore.
Flicking er' s pits along road just west of Jefferson ; 1873.
Schumann" 1 s pits, 3' to 18' deep, through blue clay (de-
composed slate), strike limestone at 17'.
Meyers' (Matt.) bank, at bend of RR., ^ acre, 1871,
abandoned ; 800' N. of it sandy slates dip 90, strike N.
60 T&.Nes Hill pits, insignificant.
* Statistics of mining, C, p. 30. Analyses: (1) Soft ore, iron, 39.280; sul-
phur, 0.007 (2) hard ore, iron 26.650; sulphur, 0.005. Another analysis:
Iron, 26.0; silica, 47.5; alumina, 8.65. Another: Iron, 46.13; silica, 34.10;
phosphorus, 0.22. Another (white ore): Iron, 46.100; no sulphur; phos.,
1.258 ; silica, 15.000 ; alumina, 16.000; undetermined, 21.642. Average of three
analyses by McCreath: Iron, 34.375; silica, 32.400; phos., 0.378. Average
lot of samples sent to McCrealh yielded: Ferrous oxide, 0.900 ; ferric oxide,
50.857 ; mang. sesq., 0.103 ; al., 1.630 ; lime, 0.862 ; mag., 0.303 ; sulp. acid, 0.011;
phos. acid, 0.513; water, 1.690; residue, 43.425; = iron, 36.3 ; mang., 0.07 It phos.
0.224 ; sul., 0.004. The long debate over the so called " Codorus silicon steel "
deserves no attention.
224 GEOLOGICAL SURVEY OF PENNSYLVANIA
Forrey 's bank, 200' long, 30' broad, 15' deep'; partly
washed shut (1874); 800 tons in 1869. Shaft (reported) went
through 8' stripping, 60' solid ore, bottom still in ore.
StambacKs bank, 1200' S. W. of last ; 200' long, 50' wide,
20' deep ; 1869 ; 800 tons in one summer ; ore coldshort.
Ti'ones trial shafts, 1000' N. W. of Smith's station ; ore
found ; filled.
RudesilVs bank, f m. N. E. of Smith's station; 300'
E. 12 N., 100' wide, 20' deep ; much washed in.
Mickley's bank, \ m. E. of last ; 200' long, 150' wide, 30'
to 40' deep ; f acre , abandoned.
Eckert and Kauffmart s ; f m. N. W. of Smith's station ;
1869 ; 29,000 tons up to 1874 ; ore lean, but works easy in
furnace, cold short, plenty still in sight (1874); stripping 0'
to 12' ; at W. end rock ore 30' thick exposed, in plates a
few feet thick with clay partings, dipping (average) 50, S.
32 E. ; but the general strike of hills and ore banks is more
nearly N. 75 to 80 E.* -Hartmart s bank is a continua-
tion of it eastward, separated only by a road.
Stover's bank is close to the Hanover Branch RR., 600'
N. W. of trial shaft at W. end of last.
SprenkeVs bank, 800' S. W. of last at York Road RR.
station ; acre ; 1874.
Kraber & Nes 1 bank, 500' S. W. of last ; 1868 ; f acre ;
1000 tons first year ; then Thomas Iron Co. (1870) 10 to 30
tons a day.
All these last banks are on a range through the heart of
the hydromica belt, near the railroad ; but only N"o. 54 is
located on the geological map of York county.
Along the southern edge of the hydromica belt near Xenia
and the Maryland are Nos. 13, 14. at the limit of the
phyllites :
Hof acker* s bank, a century old, 7 m. S. E. of Hanover, 3
m. from the state line ; a quarry of hardened chlorite slates
(cut by quartz veins, studded with pyrite and chalcopyrite)
nearly vertical, striking N. 20 E. 900' N. by E. from the
old bank is the new Wrightsville Iron Co. bank (April,
1874); ore limonite with some magnetite in a regular bed
*See statistics in G, p. 38.
ADAMS COUNTY LIMONITE BANKS. 225
hardly needing washing ; dip of schists in cut 50, S. 70 E.,
but in the quarry, 90, S. 70 E. Benade 1 s shaft is f m.
S. W. of the bank.
Adams county limonite banks.
McConaughy trial pits, on the H. and C. pike, 3 m. N.
W. of Hanover, for the Lochiel works (1874), is the last ore
spot on the Pigeon Hill slate ore range, but in quartzite
land. West of this nothing is noted in Report C, 1874,
p. 64.
On the York valley belt of slates, the range of banks is
continued across into Adams county by the following banks
(C, p. 42) :
Schwartz (Sam.) bank, 2 m. S. W. of Hanover ; 1874 ;
1000 tons exhausted it ; machinery standing ; ore in crystal-
line slates dipping 45, about south, conformably inter-
leaved, and also cutting the slates.
'Schwartz (Sol.) bank, f m. S. W. of last ; 1855 ; 1 acre,
30', 40' deep ; 2000 tons taken out in 1872 to 1874 ; much
ore left in floor ; walls full of wash ore.
Boyer bank, on Hanover and Littlestown RR., 3 m. N.
E. of Littlestown ; 1856 ; f acre, 15' deep.
Lefeme pits, H m. S. E. of last. Shaft 20' deep, caved
in, filled up (1874). A sandy yellow ochre ("mineral
paint") occurs.
Krumr em's pits, on S. slope of hill, f m. S. W. of last;
1870 ; 40 tons of 35 per cent, iron ore ; nothing visible (1874)
but some Codorus ore slate.
Early and Killing er" s mine, 2 m. E. by N. of Littles-
town ; 1874 ; 20, 30 tons per day, one-third lump ore for
Keystone furnace, Reading ; 2000 tons to Marietta; foundry
iron ; matrix, mouldered clay slate in place, with three
cleavage planes, with one of which the ore dips 14, S. 15
W. Limestone cut 200' west of bank,* dips 25 S. 36 E.,
and strikes N. 54 E., both uncertain.
Lefeme" s (Enoch) bank, 2 m. E. of Littlestown ; 1869 ;
*Said to carry lead ore {galena). For mining statistics see C, p. 45.
Analysis: Iron, 46.9; manganese, 0.815; sulphur, 0.11; phos., 1.224, from
average specimen. McCreath.
15
226 GEOLOGICAL SURVEY OF PENNSYLVANIA.
1200' long, 2| acres ; a 50 per cent cold-short wash-ore ;
idle from 1871 to 1874, machinery standing.
Clark (Widow] bank, 1 m. E. of Littlestown ; pits
stripping yellow and white clay ; two large pits 1000'
apart, the north one (1868) poorer ore, the south one (S
shaped, over i acre) partially filled, idle (1874), machinery
standing ; ore shelly like that of the range. Limestone in
quarry 1200' north dips 50 S. 35 E.*
Lancaster county Umonite banks.
The Chestnut Hill group of banks on Chiques ridge has
been described in the beginning of this chapter. A full
description of them will be found in Dr. Frazer's report on
Lancaster (C3, 1880, page 208 to 220), as the Sherk (No.
6) on the map ; the Copperihoffer (No. 7); the Hertzler
(No. 8); the Chestnut Hill (No. 9); the Silver Spring
(No. 10) ; and the Gamber ; all of them in the Upper Primal
Slates above the Chiques quartzite. Those which follow
are in the chloritic-mica slate or phyllite country of
Conestoga, Providence, Eden and Bart townships.
Grubb (C. B.) banks, a mile N. W. of Colemanville and \
m. from the river ; 1834 ? The decomposed schists near the
river dip 72, N. 15 W.f Open cut 130' into the hill ;
face 50' high ; stripping 6' to 10'; mostly wash ore, with
some lump, very like the York county hydromica belt ores,
ball, shell, partly manganiferous limonite with occasional
gothite. The ore is in layers between the schists, in the
bank next the river ; but solid in the heading of the north
bank. The three banks range N. 20 W. 650' long in all.
Many bombs filled with steel gray ore4
Good? s bank, f m. E. of Safe Harbor ; abandoned ; black
magnetic sand strewn along the road ; as also near the
foot of the hill by Colemanville.
*In Report C2, page C 201, 202, a little further information is given re-
specting the ore-producing chlorite-hydromica belt south of Littlestown to
the Maryland State line.
f Finely laminated gneiss near by dips the same.
JJ. B. Britton's analysis found: Iron, 53.59; ox., 20.42; water, 11.76; sil.
matter, 10.08; soluble, 0.66; sulphur, none; phosphorus, 0.44; ox. with
phos., 0.57 ; alum., 0.64; lime, 0.22; magnesia, 0.04.
LANCASTER COUNTY LIMONITE BANKS. 227
Reeves & Co. banks, 330' N. E. of the first Grubb bank ;
abandoned, 1866.
Shenk (M. R.) banks ; opened before 1840 ; 4 or 5 acres ;
abandoned ; are lean and shelly; dip in mouldered mica
schist and hydromica slate, 50, N. 15 W.
Peacocks mine, in New Providence, back of Groflfs
hotel; 1874; 65' by 50', and 35' deep, fallen shut (1877);
ore in laminated gneiss full of iron, flat balls, not magnetic.*
Mowzer s mine, m. S. W. of last ; 1867 ; cut N. E. S.
W. 500' long, 70' wide, 35' deep ; walls of white and red
clay ; ore, limonite balls in very quartzose gneiss ; large
lumps of good ore and milk white quartz strewed along
the road.
Eckman & Patterson's pit No 2, nearly 1 m. S. E. of
last ; 1867 ; new mine worked in 1877 for Port Kennedy
Furnace ; limestone (struck at 50') highly crystalline and
micaceous. Pit No. 2, | m. E. of last ; 1 acre; mass of ore
in north end (50' high); dip, 35, N. 15 west ; ore, as crusts
of limonite on prisms of laminated gneiss, filled with grey
micaceous sand.
Geiger's bank, not far S. E. from last ; 1857 ; once yielded
20 tons daily, for furnace in Lancaster ; ore excellent, thick
and compact, in some places loose ; was to start again July
1877 (Report C3, p. 228).
Cook, WrigJit & Co.'s mine, worked before 1776 for the
old Mill Valley furnace ; bought by Cook & Wright 1867,
who took out 20 tons per day, all wash ore but lump.
Geo. Bear's and SJientf s banks adjoin on the west.
Brooks'*, Montgomery and Reading RR. banks lie still
further west. Geiger & Baer took out 40,000 tons ; ore in
bottom too solid to pick and not solid enough to blast.
Myers (B. B.) bank in Eden township.
Smith (Stewart) bank, | m. E. 20 N. from last.
Lefecre (Dan.) bank, % m. N. of Quarry ville ; 20 tons a
day ; 10 per cent. lump.
Cabeen & Co. bank, just N. of Camargo ; worked by Jas.
Hopkins for 30 years ; 25 tons per day for last two years
(1877); ore once hauled 5 m. to Conewingo furnace ; iron
* Reported, magnetic ore found in pit \ m. N. E. ; gneiss.
228 GEOLOGICAL SURVEY OF PENNSYLVANIA.
greatly praised by Admiral Dalgren for naval ordnance ;
pit 1000' long, 100' broad ; full of water (1877).*
Meyers (B. J.) bank, on Keens run, Eden township ; 1835 ;
worked 1873, 1874, at 15 tons a day ; ore same as Cabeen's ;
25 per c. lump. Peacock and Thomas bank. Brooks
bank, old, same range and i m. W. of B. B. Myers ; 1835 ;
worked for twenty, years. Eckert & Go. mine, 1 m. E. of
Quarryville. Eckert & Hensel bank, H ni. N. N. E. of
Quarryville ; old ; 1830 for Mt. Eden Furnace.
Herr's bank, 1 m. N. W. of New Providence, on the edge
of the limestone, just north of the Lancaster and Quarry-
ville RR. ; 1852 ; 1000 tons per year for the Phoenixville
Furnaces.
Mylin bank, 2 m. N. W. of last in the limestone region.
(See*C3, p. 236.)
Welsh mountain banks.
In Caernarvon township of Lancaster county just north of
the Chester county line, and on the north slope of the Welsh
mountain facing the hydromica slate ridge at the south edge
of the Conestoga valley, are a row of limonite iron mines,
excavations in debris mainly composed of fragments of
quartzite, the disintegrated grains of which compose the
subsoil, in which the iron set free has collected into brown
and red hematite ore in deposits of white and pink clays
lying upon the solid quartzite strata, as at the Chestnut
Hill mines near Columbia described at the beginning of
this chapter. The ores are in the Upper Primal slate forma-
tion.
Shirk's bank, 1 m. S. S. E. from Church town ; leased
1872 ; worked to 1876, at 25 to 30 tons per day ;f ore in nests
and pockets ; in limestone slates, no other rock visible.:}:
*See valuable mining statistics for this and the banks preceding and sue-'
-ceeding in C, p. 231 <fec.
f See full account of force, machinery &c. in C3, p. 239.
t A drift 100' long driven S. into the mountain filled with water during Sun-
day ; on Monday a hole opened in the floor of the drift 50' from entrance into
which all the timbering fell, apparently into a cavern in limestone. Dr.
Frazer supposes the ridge in front of the mountain to be anticlinal making
a south dip at the mines. C, p. 240, 241.
WELSH MOUNTAIN LIMONITE MINES. 229
McKay's mine, \ m. S. by W. of last; 1876 ; small.
Slolzfuss opening, a little S. W. of last ; a few tons ex-
tracted. No exposures for 2 miles further.
Shirley's bank, near Shirk's bank ; 2 acres ; depth 60' in
south heading ; stripping 30' of white and pink clay ; in
bottom a great square shaft reaches dark brown and black
ore like that which at Chestnut Hill immediately overlies
the quartzite. Structure obscure, but apparently two syn-
clinals and one anticlinal and half of another in the length
of the bank. A pit 20' deep rapidly filled with water ; 30'
of drilling then went through dry black powdery ore.
German's bank, 150' E. and W. and 50' broad ; clay dip-
ping 20, N. 16 W. ; full of water ; much black lump, man-
ganiferous, left lying about ; soil, clay and quartz gravel.
Smith & Sons 'bank ; \\ acres ; 40' deep to water ; plane
steep ; machinery standing (1876) ; dip apparently 45 N.
but very uncertain. Beartown old mine ; 1861.
Beartown new mine ; 1873 ; 2 acres ; 250' long (N. and S.)
and 170' broad ; S. E. dip in the S. heading soon rolls over
to a gentle N. W. dip continuing to N. end of mine.*
Sens inning bank, ad joins last on W. ; 1875 ; 20 tons a day.
Russel bank, close to last ; 1870 to 1877 continuously at
25 tons per day for Seyfert & McManus (like the last) ; i
lump, f wash ore.
Garmarts bank ; 1875 ; Levi B. Smith ; 30 to 40 tons of
limonite per day; lump ore.f
Northampton county limonite mines.
The limonite mines of Northampton, Lehigh and Berks
have been described by Prof. Prime in his Reports of Pro-
gress D, D2, and D3, Vol. I.
In these reports the Chiques quartzite is always called
Potsdam sandstone. \
* Copious mining statistics given in C3, p. 244.
fFor the Warwick and other mines in N. Chester Co., and the Jones and
other mines in S. Berks Co., the reader is referred to a subsequent chapter ;
as their geological place is not fixed, thay shall be grouped with the Dills-
burg mines of York, etc.
JThe following description of the rockoughtto have been quoted in Chap-
ter XVI, page 179. The quartzite outcrop extends from E. Penn RR. June-
230 GEOLOGICAL SURVEY OF PENNSYLVANIA.
The Upper Primal or hydromica slates overlying it are
always called by Prof. Prime damourite slates. These
form the lowest division of the Magnesian limestone series
(the Calciferous sandstone formation as it is known in New
York), containing extremely variable percentages of the
carbonates of potash, soda, lime, magnesia and iron ; and
they moulder away at the surface of the ground (and as far
beneath the surface as the rainwater penetrates the earth)
into white and tinted clays holding the concentrated, oxi-
dized and hydrated iron in the shape of ball ore, which at
the bottom is often a solid mass, and occasionally crystal-
lized into pipe ore.*
tion (with one interruption) all the way to S. Bethlehem. It is a hard com-
pact rock of greyish tint, weathering yellowish from the iron it contains.
Small dots and specks of weathered out felspar make it pockmarked. Its
total thickness measured at one place is only 21'. At C. Raw's opening
(close to RR. track) it lies conformably on the gneiss, for a short distance,
thus : sandstone ; under this, damourite slate with a little magnetite, only
2 inches ; then distinctly bedded gneissic rock, only 18 inches; then, gneissoid
rock with mica and partly altered hornblende ; then hornblende rock de-
composed to a sort of serpentine ; then normal syenite.. A little further
east, the upper beds are typical quartzite ; the lower beds a conglomerate of
rounded quartz pebbles from the size of a man's head to a hen's egg, or
smaller, often with fragments of perfectly fresh dark red orthoclase felspar :
also well preserved scolithus linearis (worm-burrow casts). Eastward, it is
typical quartzite, until at S.*Bethlehem red shale (much like Trias shale)
takes the place of the quartzite. Behind the University it is quartzite. In
the RR. cut it dips N. W. unconformably over syenite. East of Lower
Saucon church bowlders mark its outcrop, close to syenite. Further E., on
the J. Bergstresser's farm, trial ore-pits struck decomposed sandstone.
Close to the Delaware, it is a conglomerate of nut-sized rounded quartz
pebbles and small pieces of felspar, graduating upward into sandstone, and
still higher beds of the Calciferous sandstone. For its other outcrops in
Northampton county see Prime's Report D3, p. 208. See also his resum6 of
Fontaine's sections in Virginia, and Saftord's in Tennessee, on pp. 211, 212.
* As a pure mineral damourite is essentially a hydrous silicate of alumina
and potash ; and in form it is a hydrous muscovite mica, the white (or silver
grey) scales of which make up sometimes as much as one-half the body of
the slaty rock. One of Dr. Genth's analysis of this slate reads : Sil. acid.,
45.57 ; alumina, 34.83 ; potash, 10.16 ; water, 5.30 ; perox. iron, 2.94 ; soda, 0.87 ;
magnesia, 0.83; lime, 0.40. (Report B, p. 123.) In four analyses the dam-
ourite mica made up 28.39, 49.70, 53.02 and 55.40 per cent of the slate. A
fifth analysis showed phosphoric acid, 0.102, and sulphuric acid, 0.110, which
probably were connected with the iron in the specimen of slate (ferric oxide,
3.79). Damourite slate has a soapy, unctuous feel, is usually of pale straw
yellow to yellowish white, sometimes pinkish, and has a pearly lustre. It
NORTHAMPTON COUNTY LIMONITE MINES. 231
Professor Prime's general description of the limonites of
Lehigh county will apply to those of Northampton and
Berks as well, and to those of Lebanon, Dauphin, Cumber-
land, Franklin, which are but local repetitions along the
same grand belt of valley limestones, in damourite lower,
middle and upper slates. I give it here in a condensed
shape, for convenience. He says :
The ore occurs massive, earthy, botryoidal, mammillary,
concretionary and occasionally stalactitic. It has a silky,
often submetallic lustre ; sometimes dull and earthy, color
of fracture various shades of brown, commonly dark, never
bright ; when earthy, brownish yellow, ochre yellow. Stal-
actites at the bottom of mines are pipe ore. Hollow concre-
tions are pot or bombshell ore ; full of water, or of sticky
clay ; inner walls glazed with oxide of manganese. Solid
balls have cracked and honeycombed cores. With the com-
mon limonite sometimes occurs scaly-fibrous or feathery-
columnar mica-like lepidocrocite of yellow, reddish or black-
ish brown color, holding about 63 per cent, of iron, but of
no money value because in such small quantity. Most of
the ore is in pieces so small as to require washing to carry
off the clays in which they are embedded.
Ranges of Northampton banks.
The principal range is along the north slope and foot
of the Lehigh mountains facing Easton and Bethlehem.
Others are in the small limestone valleys between the mount-
ains. Others are in the limestone country (Formation No.
can rarely be got in a perfectly fresh condition, except in mines actively
worked. On exposure to the weather the slate soon begins to decompose
and turns to unctuous clay. This clay is generally brown or yellow at first,
but in time bleaches white. The decomposition of the slate is probably due
to the presence of the potash and soda, and hastened by carbonic and humic
acids in the rain water. The two following analyses of (1) a white and (2)
a yellow clay from the 'same pit are instructive : (1) Sil., 72.2; fer. ox., 1.0;
al., 21.8 ; mag., 0.7 ; lime, 0.2 ; soda, 2.1 ; pot., 3.0 ; water, 4.7. (2) Sil., 64.6 ; fer.
ox., 5.6; al., 22.8; mag., 1.3; lime, 0.4; soda, 2.8; pot., 3.25; water, 4.7. The
most notable difference between the slate and the clay is (1) the excess of
silica in the clay, on account of the great quantity of tree quartz left behind
in the mass; (2) the excess of iron ; (3) the great loss of potash, proving that
the formation of soluble salts of potash is the cause of the destruction of the
slate. (D, p. 13, 14.)
232 GEOLOGICAL SUKVEY OF PENNSYLVANIA.
II) north of the Lehigh. Others are along the north border
of the limestone in a range of damourite slate at the south
edge of the great roofing slate country of the Hudson River
slate formation (No. III.) There is no essential difference
between exhibitions of ore in Northampton and Lehigh
counties except in the matter of quantity; Northampton
being far behind Lehigh in this respect.
The eight mines at the foot of the mountain from the
Delaware river at Easton to the Mary Brotzman mine (No
47 on the 6- sheet map of the county, in Prof. Prime's Re-
port D3, Vol. 1, 1883) are underground workings, on ac
count of the very heavy stripping ground which would haye
to be removed to work the ore in open cuts or quarries.
These underground mines are: Seibert's (two); Hess;
Lewer ; Glendon I. Co. ; Woodring (J.) ; Miller ; Sampson.
Then follow on this range : Sampson & Sitgreaves ;
Heckman; Hahn (Adam); Glendon I. Co.; Woodring
(Enoch); Hahn (W.); Boyer; Crawford; Wolf (R.); Nolf
(T.); Brotzman (J. L.); Brotzman (Mary, Nos. 44, 46, 47);
Jacob; Richard; Brotzman (Mary, No. 48); Richard (T.);
Lerch.*
In the mountains are : Walters (worked for the Dur-
ham I. Co.); Joy (Nos. 53, 55); Raub & Lerch; Stout &
Riegel.f
* Of Prof. Prime's notes on the Northampton mines along the foot of the
mountain I select the following, from D 3, Vol. 1, p. 194, etc. :
Jacob Crawford, (No. 43) 2 rn. S. W. of Easton; shaft 18' down to 6';
lump ore; interval ? 60' ; second bed of ore. Mary Brotzman (No. 44)>
shaft 64' to upper ore, 4'. M. Brotzman (No. 46), open cut, no regular bed;
alternate beds of dark brown and light yellow decayed damourite slate ;
flint with the clays ; dip, 17, N. 72 E., perhaps conformable to surface over
which the clays have washed. M. Brotzman (No. 48), small open cut ;
little ore in partially decomposed slate ; W. end ore in bottom ; thin streaks
of manganese oxide in the face prettily crystallized. (N. B. The miners
were carefully picking this out to throw away, and were much astonished
to learn that it was valuable.) T. Richard, 3 m. S. W. of Easton ; open cut :
ore interstratified between white clays ; shaft 107' down through slate and
clay to ore " 27' to 40' thick " on a floor of " black dirt" (D3, Vol. 1, p. 194. )
f Raub & Lerch (No. 54), 5 m. S. of Easton ; shaft sunk 15' to ore, and
100' to ore; 3 beds of ore reported, middle one only minable; partings
damourite clays. Joy (No. 55), 2 shafts, 50' and 75' deep, to ore in damou-
rite slate and clay. &t Stout & RiegeVs abandoned mine, 5^ S. W. of Easton,
magnetic ore occurs near the limonite pit.
a
:
LEHIGH COUNTY LIMONITE MINES. 233
All the mines thus far mentioned are on outcrops of the
ower damourite slate formation at the bottom of the great
imestone series.
Mines north of the Lehigh river and in damourite slates
)f various horizons in the middle and at the top of the
imestone series are thus named and described in D3:
Biery(Jas.); George (Ab.); Chapman; Lerch; Shinier (No.
| )) ; Ritter (Simon) ; Goetz ; Gernert ; Merwin & Shortz ;
\ohler; Ritter (W.); Schortz (Nos. 12 and 14); Hummel;
3eck (W. G.); Beck (J.); Lawall ; Woodring; Gernert &
leller ; Messinger & Woodring ; Moser ; Fogel ; Young ;
5chimer (No. 24); Walter; Richard (T., Jr.); Messinger.
Lehigh county limonite mines.
There appear to be four lines of ore deposits across Lehigh
Bounty. (7) A southern range along the foot of Lock
Ridge, on a general N. W. dip like the rocks on which the
)re (and damourite slate) rests. In this range are the mines
:>f Wagenhorst ; Wescoe ; A. Hertzog ; H. Kaiser ; Meitzler ;
Ludwig, Hertzog and Liess ; Kreishman (2) ; Gaumer ;
erschner (2) ; Schwankweiler ; Crane I. Co. ; Allentown I.
Jo. ; Wiand ; Laros ; Marck ; and those at Hunsingerville,
tfhich are so grouped together as to constitute one great
rregular excavation, viz : Maple Grove pits ; P. Kline's
nines ; J. Barber & Co.'s ; Hensinger mines leased by the
A.llentown I. Co.; Thomas I. Co.'s; Hensinger & Saul's;
Mickley's ; Hensinger Heirs'; Keifer's ; Desh's.*
This southern range is continued eastward across North-
ampton county along the north foot of the Lehigh mount-
ain as far as the Delaware river opposite Easton, as already
described.
The second range lies in the limestone country to the
north of the first range, and embraces the mines of Ludwig
(2) ; Butz ; Yager ; H. Kaiser ; Blank ; Smoyer (4) ; B.
*Many of these mines were stopped in 1874 on account of the depression
in the iron trade. Some had been abandoned ; some had their machinery
standing, ready to be exploited again. They are all located by numbers on
the sheets of the Lehigh survey map, executed by Mr. Clark under Pro-
fessor Prime's direction, and published with Report D, 1875. Their descrip-
tions appear on pages 17 to 24 of that report.
234 GEOLOGICAL SURVEY OF PENNSYLVANIA.
Smoyer ; J. Smoyer ; B. P. Smoyer ; Judith Smoyer ; T.
Smoyer ; A. Smoyer ; Reub. Romig (2) ; P. Romig ; Werner
& Reinhart ; and Lauer.
The third range, further north, comprises the mines of
Weiler ; Crane & Thomas I. Co. ; Lichtenwallner ; Smoyer ;
Geruart ; Sholl ; J. Bastian ; E. Bastian ; and F. Guth.
The fourth range, further north, comprises the mines of
F. Breinig ; Moser ; T. Breinig ; Whitely ; Fogel ; Schwartz ;
Bortz ; Koch ; Grammis ; Gackenbach ; Fischer ; J. & D.
Smith ; Haines ; Miller ; Scholl & Co.; Steininger ; Moyer ;
Stein ; J. Laros ; Levi Lichtenwallner ; Krcemlich and Lich-
tenwallner ; and the trial pits at Chapman's station ; and
the mines in the Fogelsville Cove, although these lie really
further north next the slate region.
Ninety-eight (98) mines, mostly open quarries, large and
small, shallow and deep, are named, enumerated and located
on the first map of Lehigh county, published with Prof.
Prime's first report of topographical work done in 1874 (D,
1875).
One hundred and three (103) others were in 1875, 1876,
named, enumerated and located on the four-sheet colored
map of the county published with Report D2 in 1878.
These are classified geographically thus :
In the first range, along the foot of the South mountain:
Reder ; Desh ; Shelly ; Daney ; Schwartz (Dan.); Emaus
I. Co.; Bader; Trexler & Kline; Kline (H.) three; Kline
(Jessie); Kemmerer ; Keck & Ritter ; Kline (G.); Stein;
Hottenstein ; Apple; Kipping & Holsbach; Seam; Whit-
man ; Spinner.
North of the Little Lehigh : Reinhart ; Jobst ; Wenner;
Kemry & Carbon I. Co. ; Smoyer ; Steiner & Kehm ;
Woodring ; Roth ; Glick (L. and C.) two; Acker ; Reinhart.
In the middle of the limestone country: Schadt; Rush ;
Ritter ; Sheirer ; Mclntire ; Miller ; Biery ;.Wennor ; Roth ;
Butz & Belden ; Singmaster ; Butz ; Walbert ; Descher.
Northern edge of limestone : Barber & Aimy ; Marck ;
Scherer ; Jobst ; Kratzer ; Crane I. Co. ; Wenner ; Guth
(D. A.); Thomas I. Co.; Weaver; Klein; Sieger; Crane
I. Co.; Gackenbach ; Blank ; Guth(C.); Guth (H.); Henry ;
Boyer ; Balliet ; Levan ; Henninger ; Schadt ; Baer.
BERKS COUNTY LIMONITE MINES. 235
Mines at Ironton: Kennel (Ironton RR. Co.); Mickley;
Ironton Co.; Balliet Bros.; Balliet heirs; Brown; Bitter;
Steckle (P.); Steckle (D.); the last two east of Ironton.*
Berks county limonite mines.
The Lehigh ore belts are continued westward towards the
Schuylkill ; but most of mines named, enumerated and lo-
cated on the map of Mr. d'Invilliers' Report D3, Vol. 2,
1883, chapter 10, are next to or not far from the Lehigh
county line. The limestone valley (between the South
mountains and Hudson River slate edge hill) is narrowed
down in Berks county to about 2 miles, then widens to about
4 miles and so continues to the Schuylkill. The narrow-
ness of it just at the Berks-Lehigh line is brought about
by a jog in the South Mountains and two extensions of the
slate hills southward toward the jog ; the slates, of course,
overlying the limestone. It is remarkable that just here
have been made nearly 40 excavations, and that scarcely
any ore has been found, or at least mined, in the limestones
for the 15 miles west to the Schuylkill ; the two Moselem
banks being the solitary noted exceptions, and these lie at
the edge of the slate. These facts make it likely and in fact
almost certain that the ore deposits on the limestone surface
near the county line owe their origin to the damourite slates
at the top of the limestone series, which once bridged the
* The great Ironton, or old Balliet mine, is one of the geological wonders
of the State, an excavation 2000' long, 800' broad and 90' deep, worked for
more than half a century. But as the damourite slates of this mine are of an
entirely different, higher horizon and later age, namely at the top of the
limestone series, it does not properly come into this chapter on the lower
damourite slate belt {primal) of limonite ores at the bottom of the series.
I have found it impossible to avoid reference in this chapter to all the limo-
nite mines of the valley, because of the difficulty of selecting out those
which are exclusively confined to the lower outcrop of slate. Some of those
in the very center of the valley may be in the lower, or in the upper slates,
or in slates of some intermediate horizon. The valley limestones are ex-
cessively compressed and crimpled ; so that on lines of anticlinal the lower
slates may appear at the present surface (although that is not at all probable
except in rare cases); while on lines of synclinal the upper slates may be
and probably sometimes are preserved at the present surface. I was also
anxious to give in this chapter a general view of the iron ore wealth of the
region. The description of the Ironton mines is therefore postponed to a
following chapter.
236 GEOLOGICAL SURVEY OF PENNSYLVANIA.
valley, and still bridges it half way. And, if this be so,
then it is possible that all the 200 and more mines in the
limestone belt of the three counties must be referred to the
top damourite slates, and not to the Primal^ the bottom.
It is an additional testimony to this, that the two greatest
limonite mines of the region, the Ironton in Lehigh and
the Moselem in Berks, are in the upper damourite between
the limestone belt and the slatebelt.*
The lower damourite (Primal Upper hydro-potash-mica
slate) lying upon the Chiques quartzite, follows the north-
ern foot slope of the South Mountains around to Reading.
A group of ten limonite banks are located in the cove
at the head of the Little Lehigh. south and west of Sham-
rock (S. E. of Topton). A mine is just south of Topton ;
another, 1 mile S. E. of Bower's station ; two more a mile
S. W. of Lyons station ; five more S. of Fleetwood station ;
another (Shaefer's) i m. S. E. of Blandon station.
In Oley Valley.
In the Oley Valley, Hunter's & Weaver's mines are 2 m.
S. W. of Friedensburg ; and these are the only limonite banks
in the body of the highlands in Berks county except the
Bittenbender and Gehman banks 5 m. S. of Alburtis.
But. there are indications of a siliceous hematite connected
with the Chiques quartzite beds in many other places. The
ores of this formation where exploited have been found not
only silicious, but so phosphatic and with so little alumina,
magnesia and lime as to make cold short iron invariably.
These ores however seem in all cases to be the product of
the overylying damourite slates, the iron of which set free
has found a home in the quartzite, especially where this is
in a sandstone condition. f
The Udreeore ~ba,rik in Ruscom Manor on the N. flank of
Furnace Hill, 1 m. S. W. of Pricetown, was the largest
producing bank in the mountains in 1882 ; belonging to
*In a following chapter this famous Ironton mine will be described in de-
tail (from D2, p. 39, &c., as examined and mapped by the survey in 1875;,
because it is the best and most typical deposit of limonite in this region of
the state, and the most instructive for the elucidation of the structural rela-
tionship between the limestone and slate formations of the Great Valley.
t See D3, p. 361.
OLEY VALLEY LIMONITES. 237
the Clymer I. Co., and located in the sandstone close to
the gneiss ; worked since 1871 by the Clymer I. Co. for Mt.
Laurel Furnace ; mostly wash ore ; some bombs ; hand-
some specimens of concretions and stalactites ; varieties of
gothite, lepidocrocite. turgite, red and yellow ochre ; too
cold short for the neighboring Oley furnace ; cheaply mined
as an open cut, 70' deep ; ore dipping 70, N. 20 E., 20'
thick ; 300' along outcrop ; horses of clay ; 18 to 20 tons
per day ; analysis by McCreath : Iron 40.05 ; manganese
3.314; sulp. .003; phos. .522; sil. matter, 22.44.
The Warner mine, \\ m. S. E. of Friedensburg. at the
junction of Oley slates and limestone, the line of contact
crossing the open cut ; Clymer I. Co. for Oley furnace ;
damourite slate (turned to white and buff clay), largely used
for excellent building brick ; wrought for 18 years ; 10 to
15 tons per day ; ore dips 30 to 50 N. W. (away from
slate hill), as a bed 2' to 8' thick underlaid with clay ; shaft
sunk (1878) 49' to 2' hard ore bed ; at 56' another 8 foot ore
bed (50 per cent, lump); clay between the two beds, but
second bed nearly flat, etc. See interesting description of
efforts to get water at this dry mine on page 365.*
The Hunter mine, 300 yards N. W. of the last (Weaver),
was abandoned when visited in 1882, and is accounted
almost if not quite exhausted, being wholly in the lime-
stone One shaft was sunk 90' through yellow clay, to a
1' bed of white kaolin, under which lay V or 2' of limo-
nite ore ; under this a. little black clay holding concretions
of carbonate of iron (siderite); under this a thin bed of
mixed black, clay and limonite.t
* Carbonate of iron (siderite) has been seen here, but apparently in no
great quantity. It is important for the genesis of limonite.
f This shaft section is extremely interesting, as there can be no doubt that
the black clay must have held pyrites and siderite, and by the decompo-
sition of these the limonite was produced, precisely as in the case of the
Devonian Marcellus ore mines of Mifflin county on the Juniata river, which
will be described in a future chapter.
The kaolin in this mine has been a good deal mined. The best quality,
No. 1 white, used to be sold at from $7 to $15 a ton to Connard's paper mill
at Pleasantville,and Burgess's paper mill at Spring City. Opposite Royer's
Ford, No. 1 was a deposit 30' by 20' under 6' of cover, pinching out all
round. Of the three grades there were about 800 tons. (See four compara-
tive analyses by McCreath, D3, p. 368.)
238 GEOLOGICAL SURVEY OF PENNSYLVANIA.
The Manwiller mine, 1 m. W. N. W. of Griesermers-
ville, Oley township, entirely in the limestone, was started
in 1873 and abandoned in 1878 ; there was a fair showing of
lump, but the whole was merely a pocket like so many of
the smaller limonite banks of the region. About 2000 tons
were got. Ore can be seen cropping out in the little Dale
Forge limestone valley in Washington township. 5000 tons
were taken from the J. Rush bank in Hereford township,
now filled with water. 5000 tons were got from one of the
Bittenbender banks (in the same township) during 5 years
work ; greatest depth of open cut 50'. in limestone and clay ;
great quantity of flint mixed with the bottom ore. 1000
tons were mined from the adjacent Gerham bank, but con-
demned for its excess of silica.*
Schweitzer & Kurtz bank, \\ m. N. E. of Pricetown, and
Schaeffer' s at Fleetwood, were new mines in (1882), in
limonite which belonged to the quartzite beds. (D3, p. 371.)
The Muhlenberg (Beidler] bank, W. of Reading, in lime-
stone, an open cut 30' deep, shows much siliceous limonite,
with slate and clay holding the ore. Seitzinger bank, a
mile nearer Reading, has limestone outcrops east and west
of it. The Eureka bank, 3 m. W. of Reading, a 40' cut,
yielded cleaner cellular ore, with little or no pyrites, but
some oxide of manganese.
Cumberland County limonite mines.
The limonite mines of Cumberland and Franklin, along
the foot of the South mountains, as far as Mont Alto, are
described in a special report of the Iron Ores and Limestone
Quarries of the Cumberland Valley by Mr. E. V. d'lnvil-
liers. f
Beginning at the east end of the South mountains, 12
*These banks run parallel to and 800' S. of the magnetic, ore workings higher
up the hill in the gneiss, and have nothing to do with that ore. The mag-
netite mines of Berks will be described elsewhere.
f Annual Report of the Geological Survey for 1886, part IV with two maps.
They were also described by me in a private report, with illustrations,
published in the proceedings of the American. Philosophical Society of
Philadelphia, Jan. 3, 1873. Mr. McCreath's analyses will be found in Report
M3, 1881.
CUMBERLAND COUNTY LIMONITE MINES. 239
miles west of Harrisburg, we have (going west) the follow-
ing limonite mines :*
Leidig & Hoffer (30); Beltzhoover (29); Ege (28); Pepper
(27); Strickler (26); King (8); Pepper (7); Grove, or Peach
Orchard (6); Big Pond (4); G. H. Clever (5); Clever Mam-
moth (3); Muslin (39); Chestnut (38); J. H. Cressler (37);
J. Bridges (36); all in Cumberland county and south of the
Yellowbreeches creek and Harrisburg and Potomac rail-
road. Then in Franklin county Ahl (27); McHose (28)
on the railroad ; Cressler (29); Koser (30); Southampton
(23); Ruby (24); Gochenauer & Rohrer (25); Means (26),
all in the ravine of Furnace Run. Then along the Mont
Alto railroad Stephen's Pond (8); McNeal (7); Roth (5);
Pond No. 1 (9); Pond No. 2 (10); and the group back (E.)
of the Pond banks, viz: English (11); Promise (13); Hope
(12); Wiesling (15); Limekiln (16) ; White Rock (18);
Calliman (17); Guilford (14); then again on the railroad.
J. Rock (6); No. 32 ; George (20); No. 8 ; No. 5 ; l$o. 4 ;
No. 3 ; No. 2 ; No. 1, of the Mont Alto (1); Mill Bank
(3?); Smith and Avery (2); Wythe Douglass (22); Pass
Orchard (21); G. Rock (20); and lastly R. McCreary (19);
on the Baltimore and Cumberland Valley road.
Leidig & Hojfer's bank is a. small abandoned digging in
the cove between two of the end spurs of the South Mount-
ain, 3 m. S. E. of Boiling Springs.
Beltzhoover 'bank, 1350' long, 180' wide and 80' deep, on
the north west side of the spur ; open cut to south separated
from main ore by 200' of yellow clay ; ore body not more
than 40' thick ; 60,000 tons won.f
* On the small maps in Ann., 1886, part IV, p. 1437, the mines are num-
bered, and the names are given in the columns at the bottom of the maps ;
but on the larger maps in the Atlas to the volume (part IV) the names
alone are given. It is a pity that no geographical arrangement of mines
according to numbers was possible ; but I here endeavor to diminish some-
what the embarrassment thus produced for the reader by taking the mines
along the foot of mountain in order first, especially as these are certainly in
the Primal hydromica or lower damourite slates beneath the limestone.
t Here the ore dips distinctly 40 to 50 N. and N. E. away from the mount-
ain. Variegated clays overlie the ore on the north, and are manganiferous
Ore rests on reddish sandy slate, beneath which no ore is found. The old
Crockett bank is further west up the hollow. The Siplinger bank is also
long abandoned. Trial pits sunk westward found no ore. at least for 30
240 GEOLOGICAL SURVEY OF PENNSYLVANIA.
Ege bank (Big bank) of Phila. & Reading I. Co. 2 m. S.
of Boiling Springs, an immense excavation, practically
abandoned (in 1886) and the shafts and faces fallen in ; 1500'
long, 250' wide, 70' deep at south end. At the west end the
ore was drifted on and found always dipping steeply S. E.
into the mountain, thickening and thinning but " with an
average thickness of 25 to 40 feet."
Pockets of manganese-iron ore edge the main body, and
weathered into sooty clay masses or large spots in the white
clay mass. The wash ore is mostly removed ; the remain-
ing solid bottom ore is of poorer quality, and expensive to
mine. The greatness of this mine may be judged from the
fact that the lease called for 50,000 tons per annum ; but it
never actually yielded more than 35,000 tons in any one
year.
Pepper, or Old bank, near the head of a little limestone
valley extending around a ringer of the mountain 2 m. S.
W. of Boiling Springs ; trench 375' long, 150' wide, 45' deep ;
east end wall, buff clay and sand, wash ore ; west of plane,
white clay streak 12' wide ; balance, good and poor ore
ground mixed ; many black manganese blocks ; abandoned
(1883). In 1873 I saw a stope 70' high, showing 25' wash ore
above, 45' solid ore below, arranged in fine anticlinal arch;*
shafts from the floor down went through 35' more of solid
ore, making 100' of ore ground in all. At least 100,000 tons
beneath the surface. A low tunnel was driven in white clay along the N.
edge of the ore body to keep it in sight, and the tunnel doubled on itself N.
W. showing an anticlinal structure, such as I saw in the heading. See foot
note to d'Invillier's, p. 1468. Toward the east end the ore body swelled to
400' broad. No. 3 tunnel 775' long, from the RR. to the ore, was cut to avoid
a plane. It was driven 650' before the ore was reached, proving again the
strange S. E. dip of the damourite slate formation here. See many other
interesting details in d'Invillier's report; among them that the manganese
deposits limit the ore in this as in other banks in this vicinity. Eastward
the ore shelves up and covers a wedge of limestone 160' thick. Trial shafts
eastward have not been very satisfactory ; but it is supposed that the ore is
practically continuous to the Beltzhoover bank, 3700' distant. There is a
considerable amount of shot ore largely mixed with quartz. The trial pits
were usually in a greenish talcose slate (soapstone) of the miners.
*See my pen and ink sketch of it in Amer. Phil. Soc. Proc., Jan. 3, 1873,
page 9. I estimated a possible 9,000,000 tons along the little valley leading
up to the Strickler mine ; but it must have been an overestimate.
MOUNTAIN CKEEK LIMON1TE BANKS. 241
of ore were taken out prior to its abandonment ; ore excellent
for gun metal ; used at Boiling Springs furnace 75 to 85
per cent, to 15 'to 25 per cent, limestone ore, hematite or
magnetic.*
Strickler bank, on the high divide back of the finger
mountain and at the head of the vale of the Old mine (f m.
W. S. W. of it). It is a mile E. of Mt. Holly Springs
(paper mills). The bank in 1883 was 200' long by 120' wide
and W deep to level of water ; the mine having been long
abandoned after yielding possibly 40,000 tons.f
The ravine descending from the high divide at the
S trickier bank west down to the Mt. Holly banks corres-
ponds to the ravine descending from the Streckler bank
east to the Old bank ; and the line continued west past
Mt. Holly banks is straight up Mountain Creek valley to
the Pinegrove Furnace banks, in the heart of the moun-
tains. Why Mountain creek did not keep on and issue at
the Old bank is an interesting structural (and erosion)
question. No ore has been found in the test pits along the
ravine.
Mountain Greek limonite banks.
The first two banks ascending the valley are the Mt.
Holly mines, 1 m. S. of Mt. Holly Springs, on the south
side of the creek, 150 yds. up the slope at the foot of the
mountain. They were both abandoned when visited by
* Carlisle Iron Works property on which all these banks stand is 10,000
acres. Furnace recently (1883) improved, with hot blast, <fec. Analysis of ?
large sample by McCreath : Iron, 45.1; rnang., 0.23; sul., 0.20; sil. matter
21.02; phos., 0.176.
t The road over the divide runs along the N. side of the bank above it,
and under a remarkable cliff of quartzite, or sandstone beds, descending
(south) from the top of the mountain at an angle of 20 or 30, as if to go
under the ore, but broken off at the bank, as if it once overlaid the ore. A
curiously interesting exhibition of erosion, with or without faulting, I know
not which. I saw in 1873, 20' of lump and wash ore then worked, and a
sump of 26 deep sunk in solid ore in the floor of the bank. About 20,000
tons had been already removed, and the rate of shipment then was 18 tons a
day. McCreath's analysis of his own samples was : Iron, 43 ; mang., .01
sulp.,0.3; sil. mat., 19.0; phos., 1.4. All the ores of this range contain much
manganese and phosphorus.
16
242 GEOLOGICAL SURVEY OF PENNSYLVANIA.
Mr. d'Invilliers in 1886. Dr. Frazer describes them in his
Report C2, 1877, thus :
Thomas Iron CoSs banTc\ 225' long; 225' wide ; begun
about 1872 ; average production 30 tons per day ; nearly
exhausted and half full of water in 1876. In the southeast
heading the edges of the slates, converted into ore bearing
clay layers, dip visibly 55, N". 60 W. Bands of limonite
concretions are interbedded with pink, white and yellow
clays much crumpled with N. W. and S. E. dips. Red
oxide stains some of the clays a bright red.*
Medlar and Baylor's lank* 200 feet S. W. of the last,
is an open quarry (about 2 acres), 600' long by 200' to 300'
wide, and 20' to 30' deep ; begun by Geist & Krauf t in 1840;
first really worked by Medlar & Saylor in 1870, on a 4000
ton per annum lease at 75 cents royalty ; daily average 70
to 80 tons in 1876. f
Grove bank, Hunter's Run station, 2 m. above Mt. Holly,
south side of the creek, just above the mouth of Hunter's
run. Opposite to it, north of the creek, and up the foot
slope of the north mountain, are the four following banks
in a row :
Lehman bank, opposite the Grove bank, idle in Oct.,
1886 for want of water ; a bore hole went down through ore
for 31)0' ; then through blue clay, 40' ; then white clay, 30' ;
then "mountain clay," 25' to "Potsdam sandstone" (Mt.
Holly c[uartzite)=435'4 In 1887 mining recommenced ;
pit then 250' long, 50' wide ; ore excellent; ore in places ;
but average of mine ore to clay only 1:8 or 1:10 ; no solid
ore ; dip very irregular.
*No. 159 on the map of York and Adams Co. in C2. Medlar bank, on map
to An. Rt 1886, iiii, p. 1463.
fit Is said 1000 tons a month was mined out ; and that much good ore re-
mains ; but the ore of both these pits is rankly cold short, and mining costly.
At least 100,000 tons have been taken from the two pits to mix with Cornwall
ore in the Harrisburg furnaces. Analysis of McCreath's sample of mixed
lump and ball : Iron, 38.25 ; mang., 2.73 ; sulp., 0.005 ; sil. mat., 23.55 ; ptios.,
1.37. Of dark brown cellular lump : 48.50; 0.73; 0.006; 11.27; 1.62. (d'Invil-
liers, 1886.) See statistics of wages and machinery in 1874, in C2, p. 240.
JThese figures must be very misleading considering the steep dip of the
quartzites at Mt. Holly, and consequently of the slates, which have decom-
posed into ore bearing and other clays.
MOUNTAIN CREEK LIMONITE BANKS. 243
Crane Iron Co. banks, in. W. of last ; open cut 250'
long, 50' wide ; tunnel driven in at lower level from washer;
bottom of cut being sloped down to tunnel ; stripping 20' at
the least, and up the mountain (over the best ore) ' 'enor-
mous," mostly of sandy blue and white clay ; output, 1886,
30 tons a day for Columbia, Pine Grove, Dunbar and New-
port furnaces ; afterwards increased. East of pit a shaft
went through 50' ore ; cross cut through 50' ore and clay.*
Dunbar (R. Boyer] mine, i m. W. of the Crane ; new in
1887 ; shaft 60' deep ; main gangway (northward) through
140' ore clays, then 80' through barren clays ; drift west-
ward 150' in ore clay, lean, 1:10 ; two drifts (eastward) meet-
ing irregular and thin deposits of ore.f
Chestnut Hill bank, adjoining the last at the west end of
the row, \ m. N. of the railroad and 1 m. W. of Hunter's
Run station ; ore crops abundant ; tunnel to take the ore
beneath heavy stripping commenced in the autumn of 1886 ;
ore body tested to depths of 30' to 40', E. and W. of tunnel;
large pump on the creek for water supply ; tunnel mouth
110' above RR. grade ; strikes ore clay at 130' in and keeps
230' further in ; ore ground rich and lean alternately; most
of the lump ore next the mountain ; wash ore on varigated
clays in front of it towards the valley ; average ore to clay,
1:10 ; ore rich (47 to 49 per cent.) low in phosphorus (.08
to 1.0); 3000' of outcrop tested by trial pits and shafts ;
ore for Chestnut Hill furnaces.
Koontz & Meyers bank, opposite last on south side of
creek; small ; abandoned for years.
Diverts bank, just west of last ; small ; abandoned.
Henry Clay bank, west of last ; 150'x60'; full of water
in 18864
*The stratification of ore and clay in bands and irregular masses is very
marked in this bank ; but so wavy as to prevent any theory of general dip
structure. There has been a vast deal of settling and sliding and com-
pression during the process of slate mouldering and ore concentration.
fThe main tunnel seems to have gone through three distinct ore beds, 2'
to 3' thick each, separated by barren clays, in the first 140', as described in
the text; all the ores and clays standing vertical, i. e. varying between 70,
N. and 70 S. In strong contrast to this the ore overhead at the end of the
west entry dipped very gently south.
t In all these banks the best ore is now (1886) entirely covered up, the
openings having been abandoned when the lump ore was met with. They
244 GEOLOGICAL SURVEY OF PENNSYLVANIA.
Seyfert & McManus 'bank ; 150' W. of last ; abandoned,
but not exhausted.
Lanigan lank, 300' W. of last ; 120'x90', 30' deep to
water ; sides covered with wash of sand and stone and
yellow clay ; 15,000 tons mined out, and good show of
lump ore in floor when abandoned.
Laurel No, <2 bank, nearly 3 m. W. of last ; 200'xlOO';
vigorously worked from 1878 to 1881 ; neutral liver colored
limonite in yellow clays.*
Laurel No. 1 bank, m. W. of last, close by Pine Grove
Furnace RR. station (2 rn. N. E. down stream from Pine
Grove); on N. slope of terrace; small cellular lump, easily
picked, and hard lump bottom ore, blasted ; chief depen-
dance of the furnace, mixed with Lehman bank ore ; out-
put running nearly up to 150 tons per day ; heavy ore to
clay 1:1; wash ore much less; dip S. E., wavy, sometimes
N. W.; tunnel from W. end N. W. towards RR. through
50' " top clay" into higher ball ore clay. Another tunnel
S. E. 230', mostly in ore ground, with blue clay intervals,
rising S. E. but wavy, most of the ore to the west of it ;
ore very dense with much flint, f
Pine Grove No. 1 bank ; 1 m. W. of last, and i m. E.
of the furnace (opposite the limestone quarry on v the north
all occur on the flat plateau gently rising southwards up the flank of the
main mountain, and are largely accompanied by quartzite and sandstone ;
no limestone showing anywhere." D'lnvilliers. Analysis : Iron, 35.85 (lump
ore, 50.25); Mang., 2.25 (0.07); Sulp., 0.03 (0.007) ;Sil. mat., 31.89(10.65); Phos.,
0.18 (0.51); McCreath.
* The mountain spur, coming from the west, south of Pine Grove furnace,
on which this opening was made, ends here, and the mine is well round its
N. E. end, on nearly flat dips, probably a dying anticlinal. Top wash ore
12' to 20'; clay 4'; lump ore masses in bottom of bank very compact. (Re-
port 1887, p. 1453.)
t May 16, 1887, of 76 car loads got 46 of clean ore, but this was from the
bottom of cut. Output in May, 50 to 60 tons per day. Water tunnel 300'
entirely through wash ore N. under RR. to creek. But this indicates syn-
clinal with flat S. dips on the northern (creek) side and very steep over-
turned dips on the southern (mountain) side. Analysis of lump ore: Iron,
42; Mang., 3.5; Phos., 0.15. Pine Grove furnace depends largely on this
mixed \ and | with softer non-man ganesian limonites from Hunter's run to
make its neutral pig. An average mix of Laurel -f i Crane (or Lehman)
gave carwheel pig (\ in. chill) analysing: Silica, 1.426; Phos., 0.305; Sul.,
0.009; mang., 2.722. McCreath.
MOUNTAIN CREEK LIMONITE BANKS. 245
side of the creek); not in work in 1886 ; lOOO'xSOO', and 60'
deep ; output from 1879 to 1885, 75,000 tons ; prior to 1879
(in company with other pits) perhaps 150,000 tons (5f wash
ore ; originally 10' clay and sand stripping, then 25' wash
ore clays, then 25' solid soft lump ; at W. end 60' stope ;
drift S. W. from here 200' and cross cut 150' to left, all in
ore ground (largely neutral ore from surface to bottom solid
lump) probably continuous ' ore ground to Old bank ';
southern face fine show of lump ore ; another drift from E.
end 200', largely brown cellular ore, with a large dome
horse of white clay.* Northern face poorer ore, and much
black clay.\
Old bank, just W. of last ; large excavation, long
abandoned. All dips of ore and limestone seen in these
banks are S. E. No N. W. dips observed ; perhaps S. E.
dips are overturns.
Red bank of the Thomas Iron Co. (abandoned) lies nearly
a mile south of the furnace ; opened in 1874 ; general dip
S. E. ; area a fifth of an acre ; 25' to 30' deep ; ball ore in
clay, and a good deal of red hematite ; yellow and white
clay beddings in natural position in the walls apparently
dip N. W. but may have crept over from a S. E. dtp4
Two large quarries of limestone lie 1000' S. E. of the
village of Pine Grove, area of both 8 acres, dips 30, 40
and 45, S 30 E. Limonite ore has been taken from one
of these limestone quarries, a single block of ore weighing
30 tons. The limestone is whitish, bluish, yellowish, very
pure and good flux.
Wild cat pits of the S. M. M. and RR. Co., 2 m. S. W.
of the furnace, shows that the limonite deposits continue
up the valley towards Adams county ; for, a large number
* Another dolomitic limestone crops out S. of this clay mass ; dips obscure.
fThe lump ore mining has been suspended because it averaged 2.25
mang. and 0.225 phos. and yet gave 40 to 42 iron. Analysis of McCreath's
samples: Iron, 42.15; sulp., 0.028; sil. mat., 20.9; phos., 0.275.
% Dr. Frazer remarks on the not unfrequent occurrence of this tendency
of the inward dipping clay walls of limonite mines to settle and reverse the
dip. To an observer facing the stope the bedding appears leaning towards
him ; but the removal of a few feet of wall will suffice to show them dipping
away, (CO bottom of p. 246).
Limestone also reported seen half a mile up the mountain side.
246 GEOLOGICAL SUEVEY OF PENNSYLVANIA.
of these trial shafts 30' to 40' deep passed through ore
ground; but the 50 per cent ore held an excessive (1.3)
percentage of phosphorus, which deterred the company
from mining.
Of course the valley must be a synclinal of Chiques sand-
stone (the debris from which largely covers" the surface),
supporting the Primal Upper (hydromica) slate formation
(furnishing the ore ground) and that supporting the lower
beds of the Great Magnesian limestone (formation No. Ila),
remnants of which have been left by erosion, as shown by
the quarries opened for flux for the Pine Grove furnace.
We return now to the north foot of the mountains, to
the banks along Yellow Breeches creek.
Limonites along Yellow Breeches creek.
Mullen (King) ~bank ; 2 pits in front of Mount Holly
gap, 1 m. W. of Papertown, 600' S. of road up the flank of
the mountain ; full of mountain wash ; ore largely mixed
with chert and cobbles of sandstone ; white clay 20' wide
crosses the mine ; long abandoned ; ore reported good, but
hard to wash ; borehole record : Surface clay, 8'; ore clays,
128'; on limestone.* Shipments of uniformly good ore to
Steelton, Newport, etc. A good deal of lump ore. Ore
largely confined to the ravine and not extending far east
and west.
Peffer old bank, 2 m. W. of Papertown, m. S. of
Barnitz RR. station, 1000' S. of RR. towards the mountain,
close to the junction of limestone and sandstone ; good ore;
abandoned for many years ; say 5000 tons won ; surface
all around pit strewn with ore over 5 or 6 acres.
From this southwest for seven miles there are no mines.
Then the isolated Grove, or Peach Orchard bank, 2% m.
E. of Jacksonville, close to the mountain, 1 m. S. of the
creek on small run ; long ago abandoned ; but Augusta and
Cumberland furnaces ran many years mainly on this ore,
using, say, 50,000 tons.
* This is very interesting. The limestone so high up the mountain face
with ore slate clays over it can only be explained by either (1) a universal
overthrust and overturn ; or (2) a fault, of which there is no evidence ex-
o.ept in the valley of the creek ; or (3) a descent of the limestone southwards
under the quartzite mountain, which is inadmissible.
BANKS ALONG YELLOW BREECHES CREEK. 247
Big Pond banks, 3 m. S. W. of the last, 2| m. S. S. E.
of Jacksonville, on the last head brook of Yellow Breeches
creek issuing from the South mountain; in the slates be-
neath the limestone; abandoned long since, although fur :
nishing small shot and some bomb-shell neutral ore.*
Clever bank, 2 m. S. W. of Big Pond; 100'xlOO'x40'
deep; stripping 10'; white, yellow and red ore clays in
lower part of limestone formation.
Cleoer Mammotli No. 1 bank, 1 m. S. of last, on first
head brook of Conococheague creek issuing from the mount-
ain ; once important ; abandoned long before 1886 ; 200'x
60'x 30' deep to standing water ; solid mass of ore reputed
to be in the floor still ; ore costly and of uncertain quality. f
The Chestnut bank and the Muslin bank lie between the
G. H. Clever bank and the railroad.
The Coffee bank and the Peacock bank hold the same re-
lative position to the Clever Mammoth ; about m. E. of
Cleversburg ; in the Primal Upper slates (damourite). The
Coffee was abandoned Oct., 1886 ; stope 40', exposed to
mountain side wash ; ore in tough yellow clay, wavy, not
rich. The Peacock was full of water. Stripping heavy, ore
phosphorus (.535).
The Greasier mine, 1 m. S. W., and the Bridges mine, 1
m. W. of Cleversburg, are in the limestone country south-
east of the railroad.
* This stream sinks in the limestone. In 1872 I sketched this range of
pits (see Fig. 13, Amer. Phil. Soc. Proc., Jan. 3, 1873). Ore at creek level
down stream, and 75 feet above stream to the south ; only one bank then
active ; surface clay, 22'; wash and lump ore 20'; clay in bottom. Elsewhere
stripping 6' on solid ore. In uppermost (south) bank limestone crops out
at surface dipping 8, S. 20 E., i. e., into the mountain; S. of which a shaft
went down through 52' of ore and clays and struck limestone at bottom.
This limestone is very ferruginous and makes excellent flux. Ore admira-
ble, neutral, always worked alone in the Big Pond furnace, m. S. E. of
bank. Output between 75,000 and 90,000 tons between 1836and 1868, making
800 tons of pig per annum (but d'Invilliers estimates it between 100,000 and
150,000 tons). Analysis: Iron, 44; sulphur., .03 ; sil. mat., 20.5; phos., 0.318.
t As I sketched it in 1872 it showed 8' surface stuff; 12' wash ore ; 6! ore
with someday ; 9* solid lump ore and still in floor; but clay bottom at W
end ; 40 tons output per day, very cold-short; output 20,000 tons.
248 GEOLOGICAL SURVEY OF PENNSYLVANIA.
Franklin county limonile banks.
Shirley's run is the county line between Cumberland and
Franklin. Furnace run, a mile further S. W., flows
parallel to it, out of the South mountain down to Shippens-
burg. Means' bank; RoTiref 's bank, Gogerihauer' 1 s bank,
are three small abandoned ore pits 4 m. up the run from
the railroad.
The Ruby (or Plaster} bank, Southampton bank close to
Southampton furnace, Koser bank, and Cressler bank, are
ranged along the run westward, down stream. The Ruby
bank is about 1200' W. of the foot of the mountain, in the
slates.
The old Southampton bank is in the slate range ; aban-
doned since 1865; 150'x50'x20' deep to standing water ; cold-
short ore.*
From the last (Furnace run) group of mines southward
(six miles) to the Gettysburg-Chambersburg turnpike there
are no mines. Here the face of the mountains is set back
(first) four miles, and then runs on to Mont Alto furnace,
4^ miles. The first (northernmost) mine of the Mont
Alto group is H ni. S. of the pike ; the rest of them occupy
the remaining 3 miles.
The west face of the South mountains south of the pike
is called the White Rock mountain. In front of it, south
of the pike, standing out in the limestone valley, is a low
ridge, a mile long, called Little mountain, and between the
two is a narrow, shallow vale (opening southward) called
English valley ; six mines are behind Little mountain, two
on its slopes and five in front of it, at its west foot.
Little mountain is an anticlinal of Primal Upper slates,
on sandstone, sinking west beneath the limestones of the
valley towards Chambersburg, and east beneath the lime-
stone in the English vale (which is synclinal) to rise again
at the foot of White Rock mountain. This accounts for
the arrangement of this Pond Bank group.
*Iron, 45.55; mang., 0.73 ; sulp., 0.013; sil. mat, 16.46; phos., 0.69. The
Ruby analysis reads : 37.2 ; 1.64 ; 0.03 ; 24.25 ; 0.61.
FRANKLIN CO. LIMONITE BANKS. 249
Mont Alto limonite banks.
Pond bank, a large abandoned open mine 80' deep, ore
superior, under 10' to 30' stripping. A shaft north of it
went through the following : Earth and white clay, 10';
sand, sharp, light colored, 5'; clay, sand and pigment, 25';
black clay, fine-grained, V; lignite, 4'; clay, sandy, grey,
1'; lignite, 18'; sand, I/; clay, variegated, 6'. (Wiestling's
report to d' Invilliers % 1886.)*
Little Pond bank, 600' N. of Mont Alto railroad, close to
base of Little mountain, formerly an open cut, afterwards
won by under-ground gangways driven S. from the shaft
to the railroad, and curving round the Little mountain
anticlinal on a very flat dip ; also northward under the old
open cut (which was 35' deep.)f
English mine, a little higher up the W. flank of Little
mountain ; open cut, 200'xl50'x30' deep to standing water
(1886). More lump ore was got from this than from any
other of the Mont Alto mines, but it carries more phos-
phorus than any other, and so work was abandoned when
Bessemer pig came into demand, as so many others of these
limonite banks have been for the same reason.:}:
Hope trial pits ; 1200' N. E. from last and rather on the
E. slope of Little mountain. Ore found to be phosphorous
(0.464).
Promise bank, in the vale on the White Rock mountain
foot slope ; actively worked in 1886 for Mont Alto furnace ;
first by open cut, 125 / xl25 / x40 / deep ; then central shaft
* I saw lignite in this bank in 1872, and reported it to the Amer. Phil. Soc.
Proceedings Jan. 3, 1873. comparing it with the well known lignite mass
in the Brandon iron mine in Vermont, and arguing from it the tertiary age
of all the limonite deposits of the Atlantic, so far as they were cavern deposits
in /Silurian limestone valleys. This assigned age, however, does not in any
way conflict with the theory of the genesis of the limonite from the dam-
ourite or hydromica slates of the Primal series.
t Two analyses: Iron, 50.55 (48.60) ; mang., 0.300 (2. 154) ; sulp., 0.054 (0.048) ;
sil. mat., 11.52 (11.68); phos., 0.157 (0.059). McCreath.
J Dip of ore gentle but decidedly S. E. into Little mountain, which, as in
other such instances, requires explanation. Ore covered with black clay,
over which is 6' to 10' of stripping. Plenty of ore left in this mine. Analysis:
Sulp., 0.015; phos., e.849.
250 GEOLOGICAL SURVEY OF PENNSYLVANIA.
70' deeper through wash ore, and 5' into bottom lime
stone. *
Guilford mine, active in May, 1887, 1 m. S. of last;
same relative position. Between them are the abandoned
Westling (1). Limekiln (2), and Calliman (3) banks. The
White Rock banks (4) is high up the mountain slope, and
does not belong to the slate range, but to the underlying
sandstone, and consequently shows the highest percentage
of phosphorus ; whereas the Limekiln ore was almost free
from phosphorus, f
The Guilford bank was (in 1887) 150'xlOO'x20' to 30' deep;
ore found on top of flat ridge a little W. of the base of the
mountain, and consequently has little stripping, say 4' to
10.':{: Ore stopes largely cut up with lean clays. More
bombshell ore has been got here than anywhere else.
The line of ore ground described above extends S. to the
RR. 1200' and crosses it into the B. George land.||
The Jacob Rock bank here is worked solely underground
for Mont Alto furnace. T No. 3% bank, on road. If m. N.
of Mont Alto ; worked in 1887 ; i acre ; small lump and
wash ore plenty ; much free silica to be picked out from
ore near surface ; none in the deeper ore, where clay takes
the place of sand ; 15 to 20 tons (washed) ore per day.
Ruth shaft. A ridge m. N. W. this last bank (32) and a
*Two tunnels diverge into the_mountain, from which gangways branch in
various directions. (See description by d'Invilliers in An. Rt 1887, p. 1432.)
In one, two beds of ore 27' and 40' thick are separated by 13' of barren clay
Total proved thicknes^s of good wash ore ground in cut and under-ground
works about 100'. The wash ore turns out a percentage of sandstone frag-
ments about as large as the largest ore lumps. These are hand picked and
thrown aside. Analysis: Iron, 54.6; mang., 0.336; sul., 0.037; sil. mat,
5.775; phos., 0.104.
f Analysis show phosphorus in (1) .087; (2) .040; (3) .070; (4) .109.
JThe heavy stripping ground has had as much to do with the abandonment
of our limonite mines as any variety in the quality of the ore ; most of them
still retaining large quantities of ore which the iron market will not pay to
uncover. It is this that has driven the miners into the new style of under-
ground driving.
These bombs are very rich in iron, but hold so much clay that they have
to be smashed to pieces and washed.
|| To the northward the abandoned McNeal bank and T. Stevens' Pond
bank carry the ore to the turnpike.
1 Analysis: Iron, 47.35; mang., 0.75; sul., 0.066; s. m., 16.02; phos., 0.197.
MONT ALTO LIMONITE BANKS. 251
mile from the mountain, and in prolongation of Little
mountain (southward), is largely slate carrying a good
deal of surface ore. A dry shaft on the crest of this ridge
went down in ore (with a few pieces of limestone and clay)
120'. The ore crop traced north is 150' wide, almost all
wash ore. Want of water has prevented the establishment
.of a mine on this ridge. Limestone, vertical (slightly S.
E., i. e., overthrown), crops out a short way from the crest
down on the N. W. flank of the ridge ; which fixes the
geological place of the slates.
The Mont Alto banks, 1, 2, 8, 4, 5, are almost a contin-
uous open cut, 9 m. S. E. of Chambersburg on the west
foot slope of the White Rock mountain ; served by a RR.
siding from the Mont Alto RR. which runs from near
Scotland, south, past Mont Alto furnace, to join the Balti-
more and Cumberland Valley RR. near Waynesborough.*
No. 1, near the furnace, long abandoned ; now used as a
sand guarry, the outcropping sandstone (to which the ore
belonged) disintegrates and falls to sand. No. 3, a little
further on (N.) close to W. side of terrace; 400'x300'x60' to
100' deep ; "worked to 120' deep ;" now abandoned. f No.
4, next it, along the terrace ; 60' deep ; output (of 15 years)
100,000 tons, all neutral ore, the main reliance of the fur-
nace formerly ; not very rich, but very free from siliceous
stuff. No. 8, 1 m. N. of furnace, on the same terrace;
crescent shaped, 500'xl50'; everywhere 20' to 30' of strip-
ping; stopped in 1883 ; shaft passed through 30' stripping
and then 70' of ore. No limestone seen here ; but the dip
is S. E. into the mountain.
Smith and Awry bank, I m.W. of Mont Alto, W. of RR.
in limestone land; 1 acre, 15' to 30' deep, increasing north-
ward ; idle in 1887 ; too much phosphorus for the Mont
Alto charcoal iron (0.415).
Mill bank ; RR. cuts (25' deep) through it, 500' long,
* For description of furnace see An. Rt. 1887, p. 1422 ; and interesting de-
tails in Frazer's Rt., 02, 1875, p. 257, et seq.
t A dome-shaped outcrop of limestone shows in it apparently dipping S. E.
into the mountain, around which the ore was quarried. A shaft 50' deep
wholly in lump ore, dipping steep towards the mountain, pinching out E.
and W.
252 GEOLOGICAL SURVEY OF PENNSYLVANIA.
with nests of ore in decomposed lime shales ; too much
phosphorus (0.439); abandoned.
O. Rock, Pass orchard^ and Douglass banks are small
deserted pits at the base of the mountain, 3 m. S. of Mont
Alto and m. E. of Quincy station. They belong to the
Primal Sandstone range. The R. MoCleary bank, 2 m.
W. of them is in the open limestone country ; 150 / x50'xl5 /
deep, with limestone in its center dipping 25, S. 70 E.
Four shafts in it (now all shut) showed that the ore was
chiefly pipe ore finely disseminated through yellow clay.
There are no mines further south to the State line, but
the same kind of ores follow the foot of the Blue Ridge
through Virginia and Tennessee ; as in the opposite direc-
tion similar large limonite mines range northeastward
through New Jersey and New York to the famous Salis-
bury mine at the N. W. corner of Connecticut, and the
Brandon mine in Vermont ; and it is not to be doubted
that if the damourite slates had been brought to the sur-
face anywhere in Middle Pennsylvania similar deposits of
limonite would have been created from them in recent
times ; but the general erosion has not gone .deep enough
for that, and the slate formation has been as yet protected
from decomposition, so that it seems useless to bore or
sink for the limonite beneath the surface.*
Path Valley limonite mines.
The Richmond, Carricksfurn and Fannettsburg ore banks
in Path Valley, northern Franklin county, are perhaps an
exception to this statement. They are situated along a
great fault, which is not perfectly well understood, and
which may possibly bring the Primal slate to the surface,
in which case the mines would belong to the lower damourite
range. But the fault more probably merely throws the
upper damourite slate against the Medina sandstone on
the slope of the Path mountain. The first theory is made
* In none of the middle counties of Pennsylvania do the Primal slates
rise to the surface except perhaps at the Tyrone forges on the Little J uniata
in Huntingdon county, where no limonite deposits appear. If present they
would greatly assistin identifying the Tyrone beds, over the precise horizon
of which hangs some obscurity.
THE TWO VIRGINIA RANGES. 253
a little less improbable from the general absence of heavy
limonite deposits along the limestone-slate contacts of Cum-
berland and Franklin counties, and also in the back valleys
except at Leathercracker in Blair county.*
The two Virginia ranges.
In Virginia there are recognized two distinct ranges of
limonite deposits : (1) A tower, massive and dense, dark
and often pitchy black ore, in the body of the Primal sand-
stone ; (2) An upper, richer, more cellular, brown or liver-
colored ore, in the overlying slates.
The lower ores are usually more cold-short. Both the
Virginian ores seem to be richer in iron with less silica than
the general average Cumberland county ores in Pennsyl-
vania. The lower range is scarcely recognizable in Penn-
sylvania ; but Mr. d'Invilliers, who is well acquainted with
the Virginia ranges, refers to the lower range the ore in
Thad. Stevens' s bank, north of his furnace on the Cham-
bersburg pike, and the ore opened in the face of the mount-
ain opposite the pike W. of the furnace. These I have
already placed in the South Mountain quartzite formation,
over the conglomerate beds, and they can have no near
relationship to the hydromica (damourite) slates at the
bottom of the limestone, nor to the Chiques quartzite under
the slates.
But quartzite beds occur in the body of the chlorite slate
formation in York county south of Wrightsville, on the
Susquehanna ; and there may be other such horizons of
quartzite older than that of the Chiques Rock. (Prazer in
C, p. 202.) Codorus ore (No. 43 of the York Co. map) in
North Codorus township, may be of this case.
GruWs Cadorus ore in quartzite.
The Grubb ore (No. 110 of the map, also called the "6V
dorus ore bank"} on the Codorus furnace lands 5 m. N.
* The Path Valley fault discovered and studied by Dr. A. A. Henderson
of the First Survey in 1839, 1840, is described, from his notes, by Prof.
Rogers, in Geo. Pa., 1858, Vol. 1, p. 322, where Henderson's sections make
the first theory almost a certainty. I therefore postpone the description of
this ore range to its geological place in a future chapter.
254 GEOLOGICAL SURVEY OF PENNSYLVANIA.
of W. of Wrightsville is remarkable for belonging to the
Chiques (Hellam) quartzite formation itself. Discovered
and opened in 1866, this iron-bearing sandstone, quarried
to the extent of 2000 to 3000 tons per annum for St. Charles
Furnace above Columbia, to mix with Cornwall ore, holds
its iron in the shape of ^ magnetite and f red arid brown
hematite; and having no sulphur and very little phos-
phorus helps to make excellent bessemer pig.*
The following description of what Dr. Chance considers
a Potsdam sandstone ore mine is very interesting and
geologically useful.
LehigTi Mountain Mining (70.' s limonite mines, 2 m. E.
of Emaus, Lshigh county, and next E. of the Kemmerer
mine ; shaft 85' deep ; cross cuts at 55' and 85' south to
ore body dipping steep (4o) N. W. away from the
mountain towards the edge of the limestone (200' to 500'
distant); ore bed varies in thickness from 40' to 5'; some-
times pinched out altogether; hanging wall clay having
layers of flint and sometimes large masses of quartzite ;
foot wall also clay ; mine down 130' (1885); ore 40 to 50 per
cent iron, rather high in phosphorus and silica ; probably
an altered pyrite ; alteration may not descend beyond 300'
where the drainage level of the Little Lehigh creek will be
reached. Outcrop line of 2 miles proved by 15 to 18 old
surface pits, abandoned because of continual sliding into
them of large quantities of quartz fragments and sand from
mountain slope above, making it impossible to get clean
ore for market. Now only the clean ore mass is taken out.
The ore bed seems to be faulted at intervals so as to present
a number of short S. S. W. crop lines arranged in echelon
* The Grubbs wrote that a mixture of } this Codorus ore with Chestnut
Hill and Cornwall ores made a soft, strong and very fluid iron. Cornwall
ore contains too little silica (6 per cent alumina to 15 per cent silica),
whereas J. B. Britton found in this Codorus ore: Iron protox., 4.13;
sesquiox., 36.08; (=iron, 28.46); ox., 17.16; sil., 33.80; al., 4.61; lime, 0.05;
phos. acid, 0.158. For description of mine and mining statistics, see Frazer,
Report*;, p. 64,^1874.
LEHIGH MTN. M. CO. LIMONITft MINE. 255
along the S. W. normal line of the mountain slope rocks,
viz : quartzite lying on gneiss. The gangway levels also
are not straight but curved, the dip changing from steep to
flat. Exceptions to the N. W. dip have been reported.
(Letter of Dr. H. M. Chance, Nov. 3, 1885.)
Copious and precise descriptions of the various Primal
(Potsdam) quartzite, sandstone and slate outcrops, expos-
ures and cuts will be found on pages 99 to 135 of Chapter
IV, of D'Invilliers' Report on Berks county, D3, Vol. 1.
256 GEOLOGICAL SURVEY OF PENNSYLVANIA.
CHAPTER XXI.
Magnetic limonite mines doubtfully referred to the Primal
slates, or to the Gneiss, or to the Trias, in York, Chester
and Berks counties.
The wording of this title is not intended to express more
than the fact that the magnetic limonites of York,. Chester
and Berks are so curiously many-sided in their relations to
the rock formations in and upon which they lie, that it is
in the case of most of them impossible to prove satisfac-
torily that they have originated from the decomposition of
iron-bearing shales of a particular age. They have all been
changed from the condition of a hydrous peroxide to that
of an anhydrous sesquioxide by the heat of trap dykes.
How far the trap has introduced iron (with copper) from
below, or how far the action of the trap has been limited
to segregating the iron distributed in the sedimentary strata,
cannot be dogmatically stated. The prime fact is that the
region of these mines is a belt of country covered now, or
once covered, by the Trias formation, the special (but not
exclusive) region of trap outflows.
In JorJc county.
The Dillsburg magnetic mines, situated in the north-
western quarter of York county, two miles from the foot
of the South Mountains and a mile more or less E. of Dills-
burg, in the Trias belt, form a group over which has been
some geological contention as to what formation they
belong to, whether to the South mountain cambrian rocks, or
to the Trias new red sandstone and shale. All the mines yield
about the same kind and quality of ore, magnetic, sulphur
and copper bearing, like the Cornwall, Jones and Warwick
ores. It is a country of trap, and dykes of trap adjoin the
ore ; which accounts for the copper, sulphur and magnetite.
But the Valley limestone No. II is close at hand on Yellow
Breeches creek, overlaid by Trias ; and a belt of Hudson
MAGNETIC LIMONITE MINES IN YORK CO. 257
River slate No. .Ill, in Cumberland county, points directly
towards Dillsburg, not 3 miles distant. The country north
of the Trias in Cumberland has parallel synclinal basins of
III separated by anticlinals of the underlying II. There
can be little reason to doubt that the Trias in York county
covers other and similar parallel rolls of II and III ; and
therefore it is entirely proper to suppose the existence of
the lime shales between II and III (the upper damourite
slates) beneath the Trias at and around the Dillsburg mines.
The situation then would be precisely that of the Corn-
wall mine, except that at Cornwall the great fault has let
the Trias down against the II-III slates. But there may
be faults at Dillsburg also ; and indeed both the great abun-
dance of trap and the general north dip of the Trias pre-
suppose them.
On the other hand, between the Dillsburg mines and the
mountain slope (covered with hydromica slates and frag-
ments of Chiques quartzite) the Primal upper slates should
exist beneath the Trias, and should furnish Chestnut Hill
ore, turned by trap into Jones Warwick ore.
The limestone dips being all steep, the cross section dis-
tance between the upper and lower slates need nowhere be
more than a mile (on a monoclinal); and, therefore, if the
Dillsburg ore be transformed damourite slate limonites they
may belong to either the upper or the lower slates ; and in
either case the trap would make them copper-bearing mag-
netic red-short ores.
But as most of the numerous mines are to all appearance
in Trias rocks they have been assigned to iron-bearing slates
of Trias age, altered by trap. If the McCormick boreholes
near Dillsburg furnish accurate data they make it certain
that some at least of the Dillsburg ore-masses are true ore-
beds lying between variously colored sandstone strata, and
not far above and below beds of limestone and sheets of so-
called white, grey and black trap.* If these rocks be of
Trias age it seems quite impossible to assign the ores of
* See borehole records (condensed) in foot note to page ; and in full in
C2, p. 216.
17
258 GEOLOGICAL SURVEY OF PENNSYLVANIA.
the Dillsbnrg district to the Primal slates. The most im-
portant mine for this side of the argument is that of the
Altland shaft or Schoolhouse mine. The most important
for the other side are the Bender and McCormick banks.
The central figure of the Dillsburg group is the
Underwood slope (formerly Mumper mine), opened 1848;
slope 290' long, 28 (average) due N.; at 26' struck ore 18'
thick ; followed it dipping more steeply ; roof trap ; floor
"sandstone intermixed witli limestone"; distance from
wall to wall "averages" 5'; but ore 6' to 30' thick met
with ; 8 side drift levels averaging 70' in length ; 3 shafts,
deepest 140'; output (1875) 40 tons per day, total output to
date (1875) say 10,000 tons ; ore solid and hard, blasted.-
very little of it crystallized magnetite.*
Underwood's new mine; 2CO' S. of old slope; one pit
10,000 square feet, 15' deep ; a derrick shaft went through
25' (20'?) trdp and then 28'+ (30'?) ore ; E. and W. level ;
slope from bottom of shaft 50' long, gentle N. dip in ore ;
6 tons a day. ' 1 A layer of limestone was passed througli"
Ore needs no washing. South of derrick shaft, 70', another
shaft through 2' trap, then 10' ore. E. N. E. of derrick
shaft, 100', a third shaft, same record. New pit sunk
through soil and gravel 30' to ore. A large pit S. W. of
main pit exhausted a pot of 5000 tons of surface ore. E.
of S. 300', a third pit (3500 sq. ft.) abandoned.
Logan's mine, 500' E. by N. of Underwood's slope;
opened in 1874 ; shaft 50' deep ; slope from bottom of shaft
28, due N. 80' long (1815); output 25 tons per day for H.
McCormick furnaces at Harrisburg ; ore magnetic, not
washed; section, soil and gravel with some bowlders of
trap, 28'; sand, 6'; ore 20'; floor rock 2'.f
King's mine, 3300' E. of Underwood's slope ; shaft sunk
(1876) through soil and loose trap, 6' ; hard trap, 17' ; ore,
9'. A level driven 20' E. in ore wedged between trap below
and hardened sandstone above, dipping (elsewhere) 23, N.
* Lowest gangway 110' long E. and 120' W. See full description of work-
ing and statistics of cost, etc., in Frazer's C2, p. 208.
| Statistics, etc., in C2, p. 211. A trial shaft 2400' N. proved some ore;
ground strewn with large bowlders of trap.
MAGNETIC LIMONITE MINES IN YORK CO. 259
40 W. As this mine was advanced (spring of 1876) the ore
steadily improved in quality downward, pyrites diminish-
ing, lime and magnesia increasing, and vein more solid.
The vein is 9' thick, viz : bottom ore, 1$' ; rock, V ; top
ore, 7'. Output 25 tons per day.* Other old pits are to be
seen in the neighborhood (exhausted ore-pots) one of which
is said to have given 2000 tons of surface wash ore, with
some N. slope ore. Massive trap is still visible in the pit.
McCormicJc & Co.' sold mine, 500' E. of the Underwood
slope ; 12,000 square feet area ; begun by Mumper in 1850 ;
shaft (in bottom of pit) 140' deep ; ore exhausted. A slope
100' N. of pit, 20, 60' long, abandoned.
McQormicK s long cut and slope ; the mine furthest north
in this group ; open cut along ore crop 500' ; roof trap, dip-
ping 27 to 34 (20, Altland) N. Westward. Abandoned
(1875).f
Smyser's open cut, 1000' S. E. of Underwood slope; ore
like that of the other mines ; total yield, 3000 tons ; pit 30'
deep in sand and gravel (no rock visible), abandoned.:}:
BeWs sJiaft, 33' deep, not far from bore hole No. 3.
* Mr. King's letter, May 22, 1876. He explains that the "fault rock " is "a
mixed up, broken up mixture of sandstone and trap rock," and that imme-
diately behind it (S.) is a ridge of dark green rock. See contents of letter
in C2, p. 213.
fBore hole No. 1, 160 N. W. of middle of this cut, went down through
clay, sandstone and clay, 14'; bastard limestone, 9|' ; sandstone, 9|'; trap,
9' ; unknown and brown sandstone, 32' ; ore, 6' ; sandstone, 4' ; lean-ore, 4' ;
total, 88'. Bore hole No. 3 ; white and red sandstone, 17' ; trap, 17|' ; black,
green, brown and white sandstones, 14^' ; total, 49 .Bore hole No. 4, 150' S.
of E. end of cut; various colored sandstones, 50'; trap (black), 16' and
(white) 63' ; ore, 1|' ; white, green and red sandstones, 42' ; total, 116'. Bore
hole No. 5, sunk in the old bank : soil, &c., 9' ; ore, ' ; sandstones, 22' ; trap
(black), 23' ; sandstone, 3' ; ore, 3| ; white sandstone, 5' ; ore, 1 \' ; white sand-
stone, 11' ; limestone and flint, 6' ; limestone and fireclay, 10' ; sandstones,
30' ; ore, 2' ; sandstone, 2' ; sandstone and ore, 3' ; limestone and flint, 6?' ;
ore and sandstone, Og' ; sandstones, 17' ; trap (grey), 2' ; white sandstone, 2' ;
limestone, 3' ; variously colored sandstone beds, 25' ; total, 191'. See these
records in more detail in C2, p. 216.
J One report says that the lessees sank 45' to ore 25' thick dipping S. E.
Another report makes the ore dip S. W. on a saddle of trap. Ore used un-
washed ; scattered through the bank ; costly mining. Two observers could
get no dip for the trap in this bank. C2, p. 217.
These works were new when visited in 1875. See details in C2, p. 218.
260 GEOLOGICAL SURVEY OF PENNSYLVANIA.
Grove's mine, f m. S. E. of Underwood slope ; worked for
2 years previous to 1875*.
Price's open cut, a mile S. E. of Underwood slope ; 350'
long by 125' broad, abandoned about 1860, after yielding a
large amount of magnetic ore ; said (in 1875) to have still a
6' ore bed within 14' of surface ; sandstone appears in the
N. side.
Fuller mine, 3 m. N. E. of Dillsburg ; begun 1863 ;
worked in 1875, 15 tons per day ; ore strongly magnetic ;
tunnel adit from railroad on bank of Yellow Breeches creek,
200' due S. and two drifts E. and W. under roof of trap, dip-
ping 24, N. W. ; foot wall greenish altered sandrock.f
Porter's bank, near the last ; worked by G-ov. Porter five
years (from 1850 -J- ?) and by A. Price for eight years ; ore
magnetic ; pit, 40' deep (14' below creek level) ; ore dipped
30 towards and under the creek ; limestone beds in RR.
cut close by dip 30, S. 10 E.%
Shelly' s mine, near the last, yielded 300 tons of magnetic
ore, 10' thick, under 20' of trap, and lying on Potomac
marble. Another shaft went through 30' of trap to ore.
A group of pits and shafts S. W. of Dillsburg, includes
Heiges' sJiaft, very little ore; Filler's trial pit ; Berg-
hart's pit, a layer of ore between red sandstone (Trias);
H. Heiges' trial pits-, A. Heiges pits, ore and trap ;
G. Heiges' shaft, 30' through trap and green sandstone ;
ore 4' thick. All these are scarcely more than unsuccess-
ful prospecting holes. Trap is abundant ; the surveying
needle is deflected ; Primal slates appear from beneath the
Trias.
Another group of pits of small size range irregularly past
Wellsville (6 m. S. E. of Dillsburg) in the heart of the Trias
*See details in 02, p. 219.
t Details and statistics in C2, p. 220. Analysis (in C, p. 74) : Iron oxides,
62.0 ; phos. oxide, 0.05 ; manganese sesqui oxide, 0.352.
JThe ore bed is reported to have been 6' thick, and opened for 25' along
the crop. Dr. Frazer thinks that by "magnetic" is not meant ore of the
Dillsburg type, but the "magnetic" ore of the York valley, and probably
belonging to the older (Primal) rocks ; Yellow Breeches creek being prac-
tically the dividing line between these and the Trias. (C2, p. 221.)
Such is the report of Mr. Snelly to Dr. Frazer in 1875. C2, p. 222.
MAGNETIC LIMONITE MINES IN YORK CO. 261
country, with abundance of trap : Lichty's, Meyers', flick-
er's, KimmeT s, Cooper's, Morganthaler' s, Wiley's, Bren-
neman's, (Jr test's, Barman? s, Gerber's, Altman's, Com-
fort's, Cadioaladef s, Bent's, Marshall's, Schluthauer' s,
Cookson's, Smith's (W. 72.), Smith s (J. T.) ; but they all
belong to the Trias, and not to the Primal slates ; as is best
shown at the ScJwoUwuse mine or Altland shaft, where the
micaceous magnetic ore bed is seen regularly interbedded
with the Trias sandstones, dipping 35, N, W., and both
sandstones and ore cut off by a vertical trap dyke, only
4' thick. Over 5000 tons were won previous to 1875.*
There remain to be noticed here a group of three mines
undoubtedly of Primal age, at the foot of the South Mount-
ain in York county :
Bender' s magnetic ore mine y 1 m S. W. of Dillsburg,
on and near the edge of the Trias ; open cut ; 1849, 200
tons ; idle until 1873, 300 tons, a pocket of ore 5' thick ;
other such shallow pockets near by ; ore magnetic.
Bender's limonite bank, m. W. by N". of last, in the
decayed Primal slate clays which form the south flank of
the mountain range ; open cut, acre ; 1874 ; output 2000
tons in 1 years and abandoned ; stripping 12' to 20', over
a mass of small wash ore and streaks of shell ore, 23' (and
more) deep ; one of the ore layers dipped 56 S. f
McCormick' s bank close to the last; a century old; worked
by many successive parties ; wash ore ; very few large
masses ; dip of richer streaks same as in Bender's bank ;
pit 35' deep to water ; no rock seen ; ore left in floor ; aban-
doned.
*This is the best example of indubitable Trias magnetic ore I know, and
deserves careful study. The gangway in ore from the shaft east shows the
ore bed varying between 1' and 6', and sometimes penetrating one side of
the trap, for a few inches only. The trap has developed ore on its N. W
side, but not worth mining. (See picture section in C2, p. 235 ; mine plan,
p. 237.)
t But the decayed slate rock layers can be easily followed by the eye, in
both banks dipping 30, S. 30 E. Many of the leaves of clay are encrusted
with limonite ; many of them are twisted and bent in common with leaves
of hard brittle ore ; showing plainly that the segregation of the ore followed
the decomposition of the clayslate. (C2, p. 229.)
262 GEOLOGICAL SUEVEY OF PENNSYLVANIA.
In Chester county.
Pickering creek heads at Windsor in Upper Uwchlan, and
flows eastward through West Pikeland (past Marisville),
East Pikeland, Charlestown and Schuylkill. to the river two
miles below Phoenix ville. The Pickering Valley RR., 10
miles long, brings down the ores to the Phoenixville fur-
naces.
The country is gneiss, undoubtedly once entirely covered,
as it now is partially, with Primal slates and sandstone ;
and these of course with the limestone, slate and sandstone
formations of the Palaeozoic series up to the coal measures.
If all these were removed by erosion, or nearly all of them,
before the New Red series was laid down upon the country,
the interval of time between the Carboniferous and Trias
required for such erosion would be incredibly great. And
yet we see the Trias resting on the gneiss along French
creek, with no appearance of a fault at the contact. The
eroded edge of the Trias across Chester, Montgomery and
Berks counties is sufficient proof of the former extension
of the Trias south westward over the gneiss region, no doubt
over the whole of it.
This is the foundation of Prof. Rogers' theory of the
Pickering Valley limonite deposits, and of others north and
south of them in the gneiss country. He supposed that
iron-bearing Trias sandstone beds caught in faults in the
gneiss deposited their iron in ores left after the general
erosion of the Trias had been accomplished.*
But it is admissible to suppose that portions of the iron-
bearing Primal sandstone and hydromica or damourite slate
formation have escaped erosion from the surface of the
gneiss and have produced limonite ore deposits here as else-
where. Although there are some serious objections to this
hypothesis (for the whole subject of the erosion of the gneiss
region of N. Chester is full of difficulties) it has some ad-
vantages over the other ; one of which Mr. Rogers himself
furnishes, when he says : " It is an interesting fact, having
*Geol. Penn. 1858, Vol. 1, pp. 83 to 90, with diagrams of faults and ores ;
copied into Report C4, 1883, p. 168.
MAGNETIC MINES IN CHESTER CO. 263
some bearing perhaps upon the question of the origin of
the iron ores . . . that several of these deposits adjoin, if
they are not closely connected with outcrops . . . of lime-
stone" as at the Lewis bank and the W. Par Jeer bank. A
still more important support to the theory is lent by the
fact reported by Dr. Frazer (04, p. 231) that exposures of
azoic slate occur in the Harvey (or Latshaw) mine. The
large Worth mine of surface limonite in W. Cain, lm. N.
of Sadsburyville, lends some support to this view, as agreed
by Dr. Frazer in C3, p. 261. The slate partings in the
limonite magnetite ore mass at the Warwick mine are de-
cidedly friendly to this view.
A group of old mines around Yellow Springs were de-
scribed by Prof. Rogers as seen by him in 1853 :
Lewis bank, still worked in 1853, 1 m. N". E. of Yellow
Springs; in narrow trough (fault?) between steep gneiss,
and gently pitching altered red sandstone and shale (on N.
W. side) ; white granite near south wall ; ore a loose sandy
mass ; bank N. E. and S. W. 40' deep ; altered red rock
holds many spangles of graphite and magnetite crystals ;
the unaltered red rock quite like Trias. A narrow strip
of limestone is said to have been encountered in this mine.
Fegley 1 s bank, % m. N. E. of Yellow Springs, separated
from the Lewis by a gneiss range ; two excavations in line,
between contorted steep gneiss and altered red sandstone
(on N. W. side) dipping 40, S. E. ; granite veins in gneiss
wall ; ore mingled in a confused mass of rotted gneiss and
granite ; but main body of ore (40' thick) is in loose earth
resting on the red rocks. Fegley bank (1853) 200' X 100' X
50' deep ; ore in bottom. Another large pit, just N. E. of
the other, has a 12' ore bed on a floor of red sandstone.*
Annual yield of the two banks in 1853, 2400 and 2000 tons.
Leased to the Phoenix I. Co. in 1865. Abandoned.
Latshaw '(later Harvey) mine, m. S. W. of Yellow
Springs, on a fault between steep gneiss and S. E. dipping
red rocks, but decomposed granite in the south wall ; ore
*The strip of red rock makes a low ridge 600' wide and half a mile long,
and the ore seems to have come from it. Mr. Rogers had no doubt of its
Trias age.
264 GEOLOGICAL SURVEY OF PENNSYLVANIA.
mass on and in crushed and crystalline red rocks, full of
graphite scales and mica, looking like gneiss. Output in
1874, 2000 or 3000" tons (Rogers). Output in 1881, 1000
tons. Exposures of azoic slates dipping S. E. occur in
this mine (Frazer).
Steitler ~bank, f ni. S. W. of the Latshaw, and on the
same fault, between a vertical granite dyke and S. E. dip-
pings crushed red sandstone.* First worked about 1800;
annual continuous output tor 8 years (1845 to 1853) 3000 to
5000 tons of rich good ore ; a little manganese oxide ; a
little pyrites ; beautiful masses of fibrous and pipe limonite
frequent ; unusual abundance of bombshell ore, often hold-
ing feathery-white mica (Rogers). In 1879 this excava-
tion was 900' long, 600' wide ; had sometimes yielded 8000
tons in a year; but was then abandoned. (Frazer, C4, p. 231.)
Raby mine, in E. Pikeland, 1 m. S. W. of Kimberly ;
still worked in 1882, 6 tons per day. Ornermine, % m. W.
of old Fegley in W. Pikeland ; worked by the Phoenix I.
Co. in 1883. Shows graphite. Fussel (Morris) mine, 1
m. W. of Yellow Springs, exhausted in 1880, after an out-
put of 250 tons. Tustin (Isaac] mine, \ m. S. of Chester
(Yellow) Springs ; opened 1851 ; leased to Monocacy Fur-
nace Co.; then in 1864 to the Phoenix I. Co.; shallow ore ;
abandoned. Prizer mine, 600' S. W. of the last ; worked
by Phoenix I. Co. from 1856 ; then by Monacacy F. Co. ;
large output ; heavy stripping ; abandoned.
Acker (E. Jones) mine, \ m. S. of Latshaw (Harvey)
mine, was worked from 1863 on by Phoenix I. Co. with a
large output ; afterwards for Monocacy furnace ; output in
1882, 20 to 30 tons a day. It was opened about 1853, on a
different fault line (600' S. of) the Latshaw fault line, be-
tween steep gneiss and S. E. dipping altered crystalline red
sandstone beds full of mica and specular iron crystals ; it
was at that time a mass of fragments of white granite,
gneiss, and red rock pervaded and cemented by limonite.
See diagram section in C4, p. 171, borrowed from Rogers'
Geol. Pa., 1858.
* See diagram cross section on plate, Report C4, p. 171, copied from Rogers'
Geol, Pa., 1858.
MAGNETIC MINES IN CHESTER CO. 265
Mosteller mine in W. Vincent, 1 m. E. of Pughtown ;
Phoenix I. Co., 1880, 15 tons a day. Analysis of ore : Iron
41.64; silica, 23.07; phosphorus, 0.46 (J. C. Smith).
Stauffer mine, f m. S. W. of last; Phoenix I. Co., 1880;
after 4000 tons output, abandoned. Green's mine in W.
Nantmeal ; Eckert & Co. ; two large excavations, i and f
m. N. W. of Barnestown station, E. Brandywine and
Waynesburg RR.
The Warwick Oroop.
The famous Warwick township mines of northern Chester,
in the trap district on the edge of Trias, are among the
most interesting and obscure of all our ore deposits, both
in respect of their relation to the rocks, and in respect of
the chemical changes which have produced the ore. The
felspathic granite or conglomerate rock at the Hopewell
mines is very interesting.
The Hopewell Furnace old mine, 1$ m. N. W. of St.
Mary's, was abandoned (1878); but ike new mine, 150' deep,
was worked by drifts and slopes, at four levels ; shaft sunk
in 1877-8 to ore 40' thick and no bottom, but said to average
only 10'; ore between a hanging wall of conglomerate (with
blue or amethyst quartz) and a foot wall of syenite or
dolerite trap ("blue rock"); ore much like Cornwall ore;
ore lying in veins or bands, dipping 35, N. 70 W. ; open cut
200' long ; old shaft abandoned ; new shaft 150' to a 12' ore
dipping 35; exhausted, for in 1882 they were robbing the
pillars at the rate of 30 tons a day (Frazer). The mine is
near the contact of the Primal sandstone with the gneiss.
Shaft sunk through trap, struck two veins of magnetic ore
dipping 30, N. 25 W., the upper one 15' to 25' thick, the
lower one 7'. The trap runs N. W.-S. E., cutting and
shifting the ore (Rogers).
Warwick mine, at Marysville, a very large old work in
limonite and magnetic ore, no doubt orginally all limonite,
concentrated from ore- bearing rocks obscurely related to
the upturned gneiss, on the eroded edges of which lies the
ore in a sheet varying from 2' to 17' in thickness.*,
* As shown in the diagram section in C4, p. 239, borrowed from Rogers'
fig. 572 in Geol. Pa., as seen in 1854. The ore is a mixture of limonite and
266 GEOLOGICAL SURVEY OF PENNSYLVANIA.
This large .Warwick mine is in a gravel mass made up of
loose fragments of syenite, quartz conglomerate, and mud
rock, mixed with sand and clay. A public road runs through
the mine.
, The new Smith" 1 s Warwick mine was opened in 1879.
In 1882 the Brooke I. Co., the principal operators, were
taking out 20 tons of magnetic ore per day.
Steele's mine, % m. N. of Marysville, abandoned long be-
fore 1850, seems to have been on a magnetite vein in gneiss
near a trap dyke. (04, 241. ) LeigMon" 1 s mine, S. of Marys-
ville, just outside the edge of a patch of Trias basal con-
glomerate, was largely opened on the outcrops of two mag-
netite veins dipping 33, N. W. ; the upper, 15' thick, pinch-
ing in 25' of depth to only 15 inches ; the lower (two or
three feet beneath the upper) 10' thick at the surface,
dwindling to 4'.* Length of crop 1500' ; length of pit 200' ;
depth of open cut 40' ; total output 20, 000 tons ; abandoned
before 1853. Knauertown mine, on S. edge of tongue of
magnetite, the agent of change being a wide trap dyke which passes across
the ore mass and throws it up on one side. The ore lies in several nearly
flat waves. The edge of the Trias new red sandstone formation laps here
over the gneiss and the iron ore. At one place the Trias conglomerate is
baked and altered, holding round bunches of various crystalline minerals,
hollow spaces (geodes) and vein strings. The geodes are lined with beauti-
ful crystals of epidote, etc., and bunches of large fine garnet (melenite).
Injections of serpentine occur in the mine. The greatest depth of the ore
below the surface was 60 feet ; over much of the ground the ore was but
little beneath the surface. Average richness 45, rising sometimes to 50 per
cent; somewhat sulphurous. The mine has been wrought for 160 years,
with an annual output for 15 years of 4,000 tons ; for the next 20 years 6,000 ;
in 1853, 12,000. The changed ore is grey, crystalline, magnetic ; the un-
changed ore is a compact closely cemented brown hematite (limonite) as in
other mines described in this chapter.
Inter stratified minutely with the ore are plates of earthy hardened slate
or shale, which sometimes swell to considerable thickness and separate the
ore mass into distinct ore beds. An intimate mixture of fine-grained ore
with the clay stuff makes the lower grades of ore. What are these slate
layers ? The resemblance of Warwick to Cornwall ores suggest that we
have at Warwick as at Cornwall a mass of hydromica slate, or rather of
lime-shales, decomposed into limonite and then partially converted by trap
into magnetite. But at Cornwall the lime shales are those at the top of III, as
at Irontoii and Moselem. It is impossible to imagine any slate at Warwick
except the Primal ; and this if present will explain the "injections of ser-
pentine" mentioned above.
*See diagram section, Rogers' fig. 571, in C4, p. 239.
MAGNETIC MINES IN BERKS CO. 267
Trias ; small ; ore and situation precisely like Warwick.
Crossley 's pits, 1m. N. of Knauertown ; abandoned before
1854 ; between walls of gneiss in a low ridge, at the W. end
of which a large vein of magnetite rapidly pinched out
downward.* French Creek magnetite mines, \ mile S. of
Harmony ville at the end of the St. Peters branch of W. &
N. RR. ; two shafts 250' deep (with hoisting and pumping
engines at both) ; capacity for output, 15,000 tons per an-
num. Ore holds sulphides of iron and copper. f
In Berks county.
The Jones ( Warwick] mine in Caernarvon township, Berks
county, 3 m. N. E. of Morgantown, and 12 m. S. of Read-
ing, worked by the Phoenix Iron Co., was opened by David
Jones in 1735 on a 1000 acre tract sold as mineral land by
Wm. Penn to Welsh iron masters as early as 16864 It
was known as a Warwick mine, because worked for War-
wick Furnace at Pottstown. It is however 5 miles W. N. W.
of the Warwick mine in Chester county. It is situated at
the head of theConestoga valley, where the Lancaster lime-
stone narrows to a point between the Trias belt and the
Chiques quartzite lying on the Welsh mountain gneiss. An
open quarry of 5 acres (in 1857) has a N. wall of (20, N.
30 W. dipping) magnesian limestone beds under which are
the ore-bearing Primal slates turned into a limonite and
magnetic ore mass by a trap dyke on the southern side of
the mine (next the quartzite). The purest and richest ore
is next the trap. Copper sulphide, carbonate and silicate
occur in the ore (as at Cornwall). The total output has
* Close by is the Knauertown (or P'rench Creek, or Elizabeth) Copper
mine, in gneiss, but with a granite S. wall, dip steep to N. ; width of lode
45' ; shaft 140' deep vertical, and 45' more on the dip, to a star of short gang-
ways in three directions ; abandoned May, 1854. Massive dyke of trap just
south of the mine, at the north edge of the tongue of the Trias. Gangue
largely calc spar, through which are scattered crystals of magnetite, pyrite
and chalcopyrite. the last most abundant at the N. wall. (Rogers, in C3,
p. 243.
t E. B. Harden, 1882, in C4, p. 244.
}See Mrs. James' Mem. of T. Potts, Jr. ; Swank's Statistics for 10th cen-
sus ; Lesley's Iron Man. Guide 1859, p. 561 ; d'Invillier's Report, D3, p. 226.
Rogers' Geol. Pa. 1858, Vol. 1, p. 182. An. Rt. Geol. Survey Pa. 1810.
268 GEOLOGICAL SURVEY OF PENNSYLVANIA.
been very great, as the mine has been wrought ever since
the Revolutionary War ; in 1853 it was 7,000 tons ; average
for the year 1850 to 1854 (during which a futile attempt to
mine it for copper also) 10,000 tons.*
The Dotterer red hematite mine in Earl township is a
remarkable instance of the uncertain relationships of some
of our ores. It is the only mine in Berks county showing
plainly, i. e., in workable mass, the two varieties of specu-
lar iron ore, viz : (1) massive, crystalline, steel gray, weath-
ering reddish ; and (2) earthy, uncrystalline, blood-red to
brown ; evidently grades in the change from hydrous limo-
nite to unhydrous specular, with or without the produc-
tion of magnetite.
The bed, 44' thick, stands nearly vertical (80) between
a foot wall of conglomerate and a hanging wall of chlorite
slate ; and is itself merely a deep red ore-charged portion
of this chlorite slate formation. The conglomerate made
up of pebbles of gneiss and quartzite, runs along the east
flank of Saw Mill Hill (near the summit of which the mine
shaft is sunk) while the crest and west flank are made by
the primal quartzite. The ore, therefore, seems to belong
to the lower primal slate formation, overturned slightly
beyond the vertical. f Some excellent red hematite has
* The geological position of this body of ore is unmistakably the same with
the whole range of Primal limonite deposits of the south edge of' the Great
Valley ; and yet the ore is classed (and very properly ) withthe magnetic iron
ores. There is less reason, therefore, to doubt that the Warwick and Pick-
ering valley ores of Chester county belong to the same Primal hydromica
(damourite) slates. The magnetite, the copper and the trap seem to go
always together, in the case of those limonite deposits which have been
wholly or partially changed into magnetic ores ; whether as, in this instance
of the Jones mine, the slates are at the bottom of the No. II limestones, or in
the case of the Cornwall mine where the slates seem certainly to be at the
top of them. Where there is no trap there is no magnetic ore, and no copper.
f See description, vertical section and mine plane by Mr. D'Invilliers in
Report D3, Vol. 1, 354, etc. In the extreme north of New York State red
hematite is mined beneath Potsdam and over slates. In Berks, Pa., the
Lock Ridge magnetic range (p. 253) seems to occupy this position. In
Virginia the red hematites occur in the lower, and the limonites in the upper
primal slates; ores however being also mined in the intervening sand-
stones and conglomerates. ( A. S. McCreath's Mineral Wealth of Va., p. 9.)
In New Jersey the red hematite comes in between marbles and gneisses ;
MAGNETIC MINES IN BERKS CO. 269
been won from Kaufman & Spangler"* s old mine in Furnace
Hill, Earl township, long abandoned, apparently in quartz-
ite.* Red hematite was got close to limonite in Brum-
bach's ore holes in quartzite on the hill 1 m. W. of Green
Hill tavern near the old Rockland forges. f
For the magnetic iron ore mines of Berks county I must
refer the reader to Mr. D'Invillier's Report D3, Chapter
VIII, pp. 237 to 351, where he will find described in detail
the interstratified magnetites of the Mesozoic conglomerate ;
the Rittenhouse Gap district, Thomas I. Co. mines, Tunnel
mine; Gap Mine range, Moll & Geary. Conrad slope,
Ginkinger, Weller, Wetzel, Miller, Dunkle, Gardner sta-
tion, Marstellar, new and old Mickley, Finlay, Fegley (S.
Boyer &Co.), Frederick, Fritch, Tutham mines ; the Rock-
land township mines. Beitler ; Ruscombmanor mines,
Clymer, Tunnel, Schittler ; Oley township, Tulley ; Alsace
township, Reading old banks ; Hartford township, Sies-
holtzville, Bittenbender, Gehman, Shimersville ; Washing-
ton township, Landis, Barto, Stouffer, Gilbert, Gilberg ;
Pike township ; Earl township, Phoanixville and Warwick
mines ; the Gabel mine ; the Fritz Island mine ; the Rau-
denbush ; the Wheattield ; and the Ruth.
but in Berks county no such alliance is known. The only instance of
micaceous red hematite known in Berks is an unworkable vein on Fritz
Island below Reading. The Dotterer mine is 2 m. due W. from Hill church ;
had 3 shafts 66', 61', and 50' deep, with cross cuts, etc., described in D3, p.
356. The foot wall for at least 75' along strike is everywhere a clay slate,
rich in alumina, poor in iron, carrying 5 per cent titanic acid ; used at
Phcenixville, at Pottstown, and (1882) at Norway (old Lawrence) furnace
to mix with more refractory magnetites, but no limonite. (See statistics of
charge, analyses, etc., on pp. 356 to 359.)
* The ore was hard, compact, lustrous, what there was of it Here occurred
also magnesite (carbonate of magnesia). See Genth's Report B, p. 157.
fThe hill is riddled with trial shafts which yield very little of this rich
and desirable ore.
270 GEOLOGICAL SURVEY OF PENNSYLVANIA.
CHAPTER XXII.
On the Great Valley.
The earliest settlers of Pennsylvania soon learned to rec-
ognize the superior fertility of limestone land.
While one stream of immigration from Philadelphia fol-
lowed the line of the Chester county valley, occupied the
plain of Lancaster, and spread itself along the Lebanon,
Harrisburg, Carlisle and Chambersburg belt, two other
streams ascended the Schuylkill, Delaware and Lehigh
rivers to take possession of the Easton, Bethlehem, Allen-
town and Rending portions of the same belt.
The distinction was then made in the markets of Phila-
delphia between the wagons which came from the Little
valley, and those which came from the Great valley. The
Little (Chester, Downingtown) valley was near at hand;
the Great (Lehigh, Berks county, Lebanon, Cumberland)
valley was far away in the interior of the State, among the
Indians and the mountains.
The Lancaster plain was popularly called the Conestoga
valley, of which the Pequea valley was a subdivision, and
was known to extend beyond the Susquehanna river as the
Codorus valley of York county.
These were the gardens of the new State, which made the
market of Philadelphia the finest in the world.
The Great valley of Pennsylvania derives its name not
only for its unusual width but for its extraordinary length.
Whereas the Little valley \$ confined to two counties, Ches-
ter and Montgomery, is no where more than three miles wide,
and is baunded by ranges of land scarcely 300 feet higher
than its floor the Great valley has an uninterrupted course
of 1000 miles, from Canada to Alabama. In Pennsylvania
it has a course of 150 miles, is in some places 20 miles wide,
and is bounded by mountain ranges 1000 feet high.
THE GREAT VALLEY.
271
Levels above tide of the water ways.
It is transversely crossed by all the principal rivers of the
middle Atlantic seaboard by the Hudson at Newburgh,
by the Delaware at Easton, by the Schnylkill at Reading,
by the Susquehanna at Harrisburg, by the Potomac at
Harper's Ferry, by the James in middle Virginia, and in
southern Virginia by the New river, which flows the other
way, westward, under the name of the Great Kenawha, into
the Ohio.
These rivers enter the valley by gaps in the North mount-
ain, and leave it by gaps through the South mountain ; and
while crossing it are bordered by hills two or three hun-
dred feet high; or in other words, the water channels of the
rivers are sunk that much beneath the average level of the
general floor of the valley, showing a remarkable uniformity
in the structure of the valley for several hundred miles.
It is only towards its far northern end that it is cut through
down to tide level, by the Hudson river.
The Delaware enters the valley at the Water Gap at 300'
A. T. and leaves it at Easton at 150' A. T.
The LeJiigh enters it at about 370' A. T. and then flows
sidewise eastward into the Delaware at Easton.
The ScJmylkill enters it at Port Clinton at 400' A. T. and
leaves it at Reading at 180' A. T.
The Swatara enters it at about 450' A. T. and then flows
sidewise westward into the Susquehanna.
The SusqueJianna .enters it four miles above Harrisburg
at about 300' A. T. and leaves it at Columbia about 250' A. T.
The Potomac enters it at about 300' A. T. and leaves it at
Harper's Ferry at about 250' A, T.
To put this in tabular form : *
A
c
I
J
.
|
f(
9
oj
X
ja'
C8
a
a
&
>>
&0
1
s
GO
02
3
a
i
3
1
North Mountain,
300'
300'
450'
400'
370'
300' A. T.
South Mountain,
250'
250'
180'
150' A. T.
* For all these levels see Report on Levels, N, 18?a
272
GEOLOGICAL SURVEY OF PENNSYLVANIA.
It is plain to see that the three great rivers which drain
a large portion of four states, Virginia, Maryland, Penn-
sylvania and New York, have cut the deepest channels ;
and that all three enter the Great Valley at exactly the
same level, 300' A.T. ; while the smaller intermediate rivers,
Lehigh, Schuylkill and Swatara, have cut down only to
370', 400' and 450'.
From the Delaware to the Susquehanna water gaps in the
North mountain the distance (in a straight line) is just 100
miles.
From the Susquehanna to the Potomac water gaps (in a
straight line) is 75 (but by the curve of the North mountain
85) miles.
From the Potomac to the James river water gaps, the
valley of Virginia is straight for 160 miles, and instead of
being crossed by intermediate rivers, is drained lengthwise,
northward, into the Potomac, by the Shenandoah river 120
miles long.
The various sections of the Great Valley are drained by
large streams flowing from divides both ways to the trans-
verse river channels ; thus : (1) The Little Lehigh eastward
into the Lehigh and so into the Delaware ; (2) Antilauna
(Maiden) creek westward into the Schuylkill ; (3) Tulpe-
hocken creek eastward into the Schuylkill ; (4) Swatara
creek westward into the Susquehanna ; (5) Connedogwinit
and Yellow Breeches creek eastward into the Susquehanna ;
Conecocheague creek westward into the Potomac.
ylk
ek
Divi
Li
250'
783'
310'
501'
200'
270'
485'
230'
150'
THE GREAT VALLEY. 273
The divides at the heads of these lateral or in-valley
streams represent the general level of the whole floor of the
valley across the state ; and the levels of these divides are
indicated by the summit stations of the various railroads
which, together, make a continuous line of traffic from end
to end. See table at the foot of last page.
By this showing the floor of the Great Valley is lower
between the Delaware and Susquehanna, than between the
Susquehanna and Potomac. But it must be remembered
that railroads follow depressions, and seek the lowest place
on a divide ; and that from Harrisburg to Newville (30
miles) the Cumberland Valley railroad grade reads : 322',
357', 436', 427', 458', 477' (at Carlisle) and 533', mostly on a
pretty level limestone plain. In the next eleven miles it
rises to 654', and suddenly then to the "summit" 783';
falling again at Chambersburg to 618' and at Greencsstle to
585'. So that in reality we may feel safe in assuming a gen-
eral level of the floor of the valley across the whole state,
as traversed by the lines of railroad, at about 500' A. T.*
* A line of levels carried along railway lines from Sandy Hook via Hagers-
town, Md., Gratton, Va., Athens, O., Mitchell, lad., to St. Louis (published
in Coast Survey Report for 1882, page 521-f, with a map of the route, page
557), fortunately for our present purpose, follows the Great Valley from
Easton, through Allentown, Reading, Lebanon, Harrisburg, Carlisle and
Chambersburg to Hagerstown, and then ascends the valley of the Potomac
on its way west
Easton. (No. XIX) Cut on one of the central piers of the RR. bridge
across the Lehigh river, 214' above mean sea level.
Easton. (XX) Cut W. corner of jail, on foundation stone, 357.5'.
Easton. (U) Sill of blind window, E. side of court house, 363.5'.
AHentown. (I) Cut on sill of basement window S. side of front entrance
of jail, 321'.
One and a half miles W. of Allentown. (XXI) Cut on N. W. corner RR.
bridge over wagon road, 295 5'.
One-half m. W. of Macungie station. (XXII) Cut on top stone, N. side
RR. bridge over small run, 383.5'.
Reading. (J) Cut on coping stone, E. abutment of N. E. RR. bridge at
RR. depot, 264'.
One-quarter m. E. of Shamrock station. (XXIII) Cut on N. E. corner
RR. bridge, 424.5'.
One-eighth m. E. of Robesonia station. (XXIV) Cut on pier of small
bridge, 432.5'.
18
274 GEOLOGICAL SURVEY OF PENNSYLVANIA.
But the lines of railroad connect the principal towns of
the valley ; and these have all been built on the most fertile
and smoothest'part of the valley floor, viz : its southern belt
composed of limestone soil ; and it is to this belt alone that
the above average of 500' A. T. applies ; its northern belt is
rougher and higher.
The two belts.
The Great Valley is divided geologically lengthwise, from
end to end, into two belts of country ; one, next the North
mountain, a slate belt; the other, next the South mountain,
a limestone belt. The line of separation in some places runs
for miles remarkably straight ; in other places it is remarka-
bly crooked ; but along the whole course it may be called the
middle line of the valley ; the slate region being to the north
and west of it ; although occasional streaks of limestone ap-
pear in the slate belt, and occasional patches of slate in the
limestone belt ; but the relative proportions in width vary,
the slate belt being nearly every where the wider of the two,
and in parts of the valley twice or even three times as wide
as the limestone belt. In Cumberland county, however,
the limestone belt is a little wider than the slate belt.
One and a halfm. W. of Womelsdorf station. (XXV) Cut at E. end of
base of N. wall of overhead bridge RR., 483.5'.
Lebanon. St. Mary's Catholic church. (XXVI) Cut on S. side of south-
ernmost front entrance ; centre of cross, on white marble block, 474.5'.
Lebanon. (K) Bottom of square hole in top of marble post in ground oi
Mr. P. L. Weiner, S. E. corner Eighth and Chestnut streets, 465.5'.
One and a quarter m. W. of Annville. (XXVII) S. W. corner RR. bridge
over Joe Crider's dam, 405'.
Swatara bridge (RR.) (XXVIII) Cut on stone parapet between Beaver
and Hummelstown station, 367.5'.
Harrisburg. (XXIX) Centre of top surface of monument in capitol
grounds, marking astron. stat. coast survey, 356.5'.
(L) Cut at base of pillar at S. E. corner capital building, 367.5'.
Carlisle. (M) Cut on base of column at W. side of jail entrance, 472.5'.
Shippensburg. (XXX) Cut on water table of house and store of W. C.
J. Reddig, N. W. Corner Main and Railroad streets, 654'.
Chambersburg. (N) Cut on pedestal at base ofN. pillar of court house
front, 620.5'.
Greencastle. (XXXI) Center of cross cut in stone in front wall of RR.
depot, 7" above sidewalk, S. of entrance, 588 5 .
Hagerstown. (A) Cut on water table of court house, corner Washington
and Jonathan streets, on Jonathan street side, 552.5' = 168.3402 meters,
THE GREAT VALLEY BELTS. 275
The Slate belt has an average general level about two hun-
dred feet higher than the limestone, say 700' A. T. This is
strongly marked all the way from the Delaware river at
Belvedere, to the Schnylkill river at Leesport, by a steep
hill-slope down from the higher slate floor of the valley to
its lower limestone floor; and this step in the surface is
made more remarkable by narrow openings or ravines from
which issue numerous small water courses heading in the
recesses of the slate land, and at the foot of the North
mountain.
This elevated terrace-like edge of the slate belt contin-
ues, although in less regular style, through Berks into
Lebanon county ; can be recognized in Dauphin and Cum-
berland counties ; but gradually becomes less conspicuous
in Franklin county. There is no mistaking, however, the
greater relative height of the slate belt everywhere along
the Great valley.
The distinction is emphasized moreover in all cases where
limestone coves invade the slate belt, and where slate ridges
traverse the limestone belt. It is evident to the most in-
different spectator that the surface of the limestone land
lies naturally lower than that of the slate land,* but a
clear exhibition is made of it by the contour-line maps of
Lehigh and Northampton counties published with Reports
of Progress D, D s and D s . These maps show the relative
levels of the whole limestone belt of the valley, of the edge
of the slate belt, and of the slopes of the South Mountains,
all the way from the Delaware to the Schuylkill rivers, f
No contour -line surveys of the Slate belt have been made
anywhere along the valley ; and until such surveys have
been made and a continuous contour- line map of it has been
* The reason for it will be given further on, in connection with the under-
ground cavernous condition of the limestone belt.
t It is evidently desirable that the Legislature should provide means for
continuing this topographial survey westward across the Susquehanna river
to the Maryland line.
In Franklin and Cumberland counties the South Mountains have been
elaborately surveyed in the same manner, and down their western slopes to
the south border of the limestone belt ; but the means of the survey were
to olimited to bear the expense of carrying the work across the limestone
land to the edge of the slate land.
276
GEOLOGICAL SURVEY OF PENNSYLVANIA.
C/i.XXII,p/ate/T
Conedoguincl Creek in Cumberland Co. fa.
THE GKEAT VALLEY BELTS.
277
I.&S'S
278 GEOLOGICAL SURVEY OF PENNSYLVANIA.
executed, no entirely accurate knowledge of its geological
structure can be obtained. We know, however, that it is
everywhere very much crumpled into narrow folds ; and
that some of these folds are so sharp that the limestone for-
mation everywhere underlying it comes occasionally to the
surface.
The north edge of the Slate belt is high up on the slope
of the North mountain ; in fact the outcrops of the top
layers of the formation run only one or two hundred feet
beneath the crest of the mountain.
Synclinal mountains of IV in III.
The upper part of the Slate formation is coarser or more
massive than the lower part, and in some places contain
pebbles in such abundance as to become conglomerate rock.
Therefore, as in some places along the south edge of the
slate belt the underlying limestone comes to the surface
along the middle line of an uncommonly sharp and strong
up/old so in some places along the north edge of the slate
belt the upper and coarser slates have been preserved along
the middle line of an uncommonly -sharp and deep down-
fold.
In two notable cases even the Medina sandstone No. IV
has been thus preserved ; and this is the explanation of
Hole mountain in Lebanon county, and ParneWs Knob
mountain in Franklin county both of them standing out
in front of the North mountain. (Plate, page 285.)
Hole mountain in Lebanon county is a ridge five miles
long ending at the Swatara river. Its top is a V-shaped
pinched stripe of the sandstone No. IV, held in a vice of
upper slates. Along the banks of the Swatara the slates
can be seen going down in front of it and coming up behind
it, and then going down again under the North mountain.
ParneW s mountain, in Franklin county, is of precisely
the same character, but longer, and produced by a deeper
down-fold (synclinal) of the slate belt. It is 10 miles long
and entirely cut off from the North mountain behind it by
the narrow straight upfold (anticlinal) of Bear valley. The
down-fold is so deep that a regular canoe of the sandstone
THE GREAT VALLEY BELTS. 279
No. IV has been preserved, its two crests being separated
by a middlegroove in which lie some of the lowest soft layers
of the Clinton red shale formation No. V.
In studying Hole mountain we make a first step towards
understanding the geology of all Middle Pennsylvania ; in
studying ParneTC s mountain we make a second step ; and
if we consider Jordan's Knob behind it, we take the third
step. For the North mountain here (at London) doubles
back upon itself (see page plate) and after zigzaging around
Horse valley, Amberson's valley and Path valley, comes
back to Loudon and runs on, as if nothing had happened
to divert it from its course, into Maryland. But all these
zigzags represent high upfolds and deep downfolds in the
slate formation No. Ill which underlies the mountain every-
where ; and not only in the slate formation No. Ill, but
in the limestone formation No. II which lies still deeper
everywhere under the slate ; for along the middle of Am-
ber son' s valley and Path valley the underlying limestone
has been brought up and bared at the surface ; while the
steep, dipping slates are confined to the side hills and to
the steep mountain slopes.*
Anticlinal bells of limestone in the slate.
The great upfold (anticlinal) of Path valley runs on from
Loudon southward bringing to the surface in front of Cove
mountain a narrow belt of limestone.
The upfold of Bear valley runs on also, by Bridgeport,
Mercersburg and Simpstown, and brings to the surface
another long narrow belt of limestone. Between these
two parallel limestone strips runs a strip of slate, preserved
in the downfold (synclinal) of Jordan's Knob. The
Loudon and the Mercersburg strips of limestone termi-
nate in two coves at the Maryland line, the Punchbowl
(or Corner), and Blair's valley; and these two coves lie
between Cove mountain and two mountain spurs in Mary-
land (Two Top mountain and Casey's knob) which ex-
actly correspond to Jordan's knob and Parnell's knob
* Along the north side of Path valley runs a great fault, so that the under-
lying limestone has slipped, up against the upper slates on the mountainside.
280 OEOLOGICAL SURVEY OF PENNSYLVANIA.
Ch.XXH, plate 3.
THE GREAT VALLEY BELTS.
281
Cross section of the Great Valley from near
Cowan's Gap south through Scotland to the
South Mountain in Franklin County, ?a.
282 GEOLOGICAL SURVEY OF PENNSYLVANIA.
towards which they look, the distance being about 14 miles.
Blair's valley is the easternmost of the two coves, and corres-
ponds in all respects to Bear valley between the Jordan
and Parnell's knobs.
The geology of this part of Fayette county is beautifully
simple, symmetrical and instructive. It is rendered still
more instructive by the following particular :
A third upfold (anticlinal) runs in front of Parnell's
mountain, and brings to the surface in the slate belt the
underlying limestone in a third long narrow slip, which
starts at a point at Strasburg, and is crossed by the Cham-
bersburg pike just west of St. Thomas, where it is 1% mile
wide. After passing St. Thomas southward this strip of
limestone becomes nearly 5 miles wide at the Greencastle-
Mercersburg pike, and so passes on into Maryland. The
slate belt, which is seven miles wide at Newville in Cumber-
land county, 6 miles wide at Chambersburg in Fayette
county, is thus narrowed to 3 miles at Welsh run and the
Maryland line ; the main limestone belt 13 miles wide bor-
dering it on the east, and the Welsh run limestone belt 4
to 5 miles wide bordering it on the west.
This widening of the Welsh Run limestone belt south-
ward from St. Thomas might have been produced in two
ways ; it was actually produced in a third way exactly con-
sistent with all that has just been said. (1) It might have
been produced by a swelling upward of the Strasburg anti-
clinal after passing south by St. Thomas ; or (2) it might
have been produced by a flattening out of its dips on both
sides ; but it actually was produced (3) by two other addi-
tional anticlinals running alongside of (in front or east of)
the Strasburg upfold; one, which may be called the St.
Thomas anticlinal, brings up a strip of limestone south of
St. Thomas ; the other, the Rock Spring anticlinal, which
brings up a little prong of limestone 3 miles S. of St. Thomas,
and after crossing the slate belt obliquely produces the
Rock Spring limestone cove 3 miles N. of Chambersburg.
These three up-folds in the slate belt of middle and
northern Franklin combine to keep the limestone up to the
surface along the Wetsh run belt near the Maryland line.
THE GREAT VALLEY LIMESTONE COVES. 283
Limestone coves in the slate belt edge.
The limestone indentation in the edge of the slate belt
at Rock Springs is about 3 miles deep. (Plate, page 285.)
Another similar indentation of limestone in the south-
east edge of the slate belt occurs at Fairview and Middle
Spring on the Cumberland county line (page plate). Both
these indentations point southwest, showing that the anti-
clinals which upheave the underlying limestone through
the slate sink in that direction.
Another indentation is shown upon the map at Newville
in Cumberland county, but it points northeast. Newville
is built in this little limestone cove and has slate hills all
round it except to the west. The outlines of slate show a
downfold (synclinal) running just south of the village.
Another very little indentation in the south edge of the
slate belt is made at Plainfield, 4 miles west of Carlisle, and
the arrows on the map along the creek here show that the
prong of slate is a true synclinal.
Another very pretty indentation of limestone in the slate
belt, two miles long and pointing (like the last two) east-
ward, lies back (north) of Kingston, six miles east of Car-
lisle. Here the arrows on the map instead of explaining
the facts are very confusing, all of them pointing south at
various angles. The cause of this will be explained here-
after, but it may as well be mentioned here that most of
these upfolds (anticlinals) and downfalls (synclinals) are
not only squeezed tightly together, but so bent over north-
ward (as if by a pressure from the South mountains) that
the strata which ought to dip north dip south, and cannot
therefore be easily separated from those which ought to dip
south. In other words, one-half of the south dipping strata
are in reality overturned and lie with their upper faces
downwards.
Another limestone cove in Cumberland county runs up
into the south edge of the slate belt in the opposite direc-
tion (northeast) behind the long prong of slate which points
out half a mile west of Kingston along a deep downfold
(synclinal) in the limestone belt. (Plate, page 276.)
No such interruptions of the south edge of the slate belt
284 GEOLOGICAL SURVEY OF PENNSTLVANIA.
Ch.XXU, plate 5~.
Specimen section ofwaveA in
7o tiluttrcdc
anticlinal Coves of JT, and. synclinal Prangs
cdong-tke center line cfthc ^eaJ;Yaflcy, Cumber/and
MOURSVILLE
,tt
TOx
FAIRVIEW
; t^ (
-25'
90
I
,40
so;
\20
diagonal and 'transverse- limes-Tone tL'jj,). ,.
THE GREAT VALLEY LIMESTONE COVES. 285
limestone and Slate belts- (M^HT) of the, 9reat Yallcy.
7o illustrate Chap, XXII of Ttnal Report IWf,
T / 4'" ' NV ' / ^N
* '' ji Chamber s'&ury *$ ^ (
* r& ** ' X . .jV
286 GEOLOGICAL SURVEY OF PENNSYLVANIA.
occur in Dauphin and Lebanon counties. In Berks county,
approaching the Schuylkill, they become very numerous,
but produce a state of things geographically so curious
and important as to require a special description. East of
the Schuylkill the edge of the slate alternately advances
upon the limestone and retreats from it in a series of small
irregular curves which scarcely disturb the straight line of
the contact; but there is a decided cove at Moselem, and
another at Kutztown, both pointing west; and together they
broaden the limestone belt and contract the slate belt a
trifle. At Monterey near the Lehigh county line, a cove
points northeast.
In Lehigh Co. limestone coves back of slate prongs play
a great role in the geography. One is produced by an an-
ticlinal passing Trexlerville ; another deeper one lies north
of it ; a third and very large one is that of Jordan creek ;
a fourth is the Ironton cove. All these point west, and
have the effect of reducing the breadth of the slate belt on
the Lehigh river to one-half of the breadth it has on the
Berks-Lehigh county line.
In Northampton county the many irregularities in the
face line of the slate belt are all of the nature of coves ; but
in no case are they shut in behind synclinal prongs of slate.
But on the other hand we have here smajl circuses of lime-
stone completely enclosed in the slate belt, back of* its edge,
anticlinal in their structure, and teaching the same lesson
as the coves, viz : that the limestone formation No. II passes
down (northward) underneath the slate formation No. Ill,
and is here and there brought up through it to the present
surface by upfolds or anticlinal waves.
Synclinal belts of III in II.
Prolong two limestone coves (one pointing east the other
pointing west into the edge of the slate belt) until their
opposite points meet, and you will have a strait of limestone
between the mainland of slate and a long narrow island of
slate in front of it ; the strait of limestone being an anti-
clinal or upfold, and the island a synclinal or downfold, or
basin.
SYNCLINAL BELTS OF III IN II. 287
Such basins of slate in the limestone belt are numerous
enough to prove that the slate formation No. Ill originally
entirely covered the limestone formation No. II.
In Franklin county one commences 3 miles South of
Chambersburg and runs 4 miles, crossing the South Penn
RR. mile from the Marion junction. The arrows near
Marion point the limestone going down very steeply under
the east edge of the slate strip. This slate strip is un-
doubtedly a closely folded downfold (synclinal).
The other is a similar little strip of slate half a mile west
of Greencastle, a few hundred yards wide, a mile or so long,
and separated from the edge of the slate belt by a strip of
limestone only a few hundred yards wide. An arrow at
its north end pointing east and three others along the rail-
road pointing west show that this little strip of slate also
lies in a closely folded trough in the limestone.
Returning now to the eastern end of Cumberland county,
the map shows the slate belt suddenly widening from 3
miles at Kingston and Hogestown to 5 miles at the Susque-
hanna river. Its edge makes a beautiful curve to the river
at Bridgeport and Harrisburg. Part of this curve is a great
fault, of which more will be said hereafter, the limestone
country has been etevated and the slate country depressed ;
so that the Connedogwinet creek, however often it tried to
break through the wall, was never able to do more than
scoop little semi-circles from it at various points along the
line ; and this explains the remarkable loops of the creek.
In Dauphin county the edge of the slate belt runs on
east nearly straight for seven miles to Beaver station on
the Lebanon Valley railroad, the railroad between Harris-
burg and Beaver keeping on the limestone. From Beaver
across to the North mountain is all slate, and the belt is 8
miles wide and continues of that width into Lebanon county,
its south edge being a very even line and nearly straight.
But between Beaver and the Swatara river towards Hum-
melstown there is a space of about a mile where the slate
belt throws a projection southward over the limestone ; and
288 GEOLOGICAL SURVEY OF PENNSYLVANIA.
this projection turns west and forms a belt of slate land in
the heart of the limestone belt, a mile or two wide, extend-
ing back 6 miles past Church ville to the Susquehanna at
New Cumberland. The river flows across this slate belt 3
miles below Harrisburg.
At New Cumberland (on the west bank of the river) this
slate belt is scarcely half a mile wide ; but it keeps on west,
in a trough of the limestone, 8 miles, and ends in two blunt
prongs one to the north and the other to the south of
Shepherdstown. Before coming to an end it broadens out
to a width of two miles, with such varieties of dip as to
baffle all explanation. Only it is evident that this belt of
slate overlies the limestone, and runs east and west about
12 miles, splitting the limestone belt into two ; just as the
three slate belts of Southern Franklin county split up the
limestone belt into four.
In Lebanon county the slate belt is unbroken by the ap-
pearance at the surface of any large appearances of the un-
derlying limestone. Its width from Lebanon to the Swatara
gap in the North mountain is 9 miles. Its south edge is
quite straight as far as Lebanon ; there bending a little it
runs almost straight into Berks county. The Union canal
on the north side of Lebanon marks the contact of the lime-
stone sinking beneath the slate. The Ime passes one mile
north of Myerstown.
The limestone belt is 1 miles wide on the Dauphin-Leba-
non county line ; 5 miles wide at Lebanon ; G miles wide at
Shafferstown; and 6 miles wide at the Lebanon-Berks county
line.
No strips of slate have been preserved on the limestone
belt, except at its southern edge, where large tracts of slate
may be supposed to overlie the limestone where everything
is covered up by the comparatively recent Mesozoic Trias
red shale formation, to be described further on.
The edge of one of these slate tracts extends for 4 miles at
Cornwall, and is visible for a mile in width along the rail-
road to the mines.*
*There may be some doubt about these slates being No. III. They may
be tbe slates beneath the limestone.
SYNCLINAL BELTS OF III IN II. 289
Another semi-circular slate tract 2 miles long (E. and
W.) and 1 broad (N. and S.) appears, at Shaefferstown.
The limestone dips beneath it all around its eastern, north-
ern and western sides, there can be no doubt about its being
a preserved portion of the slate belt, now separated from it
by an eroded interval of just 5 miles. The south border of
this patch is overlapped by the edge of the great Mesozoic
(Trias) red shale formation of Lancaster county. How far
south the slates extend under the red shale is not known ;
but no slates appear on the limestone in the Manheim,
Ephrata and Conestoga valleys in Lancaster county south of
the red shale.
In Berks county the slate and limestone belts of the Great
Valley are so intermingled that no general description
would be understood.* While the northern or main part
of the slate belt runs to and across the Schuylkill, long
prongs and strips of slate cross the limestone belt in the
triangular enlargement of the Great Valley between-
Womelsdorf, Leestown and Reading ; and long strips of
limestone traverse the slate belt north of Womelsdorf and
Bernville on the Union canal.
Southern edge of No. II.
Having thus traced the contact of the limestone and slate
belts along the middle line of the great Valley from the
Maryland state line to the Schuylkill river in Berks county,
and pointed out the streaks of limestone coming up through
the slate, and the prongs and ridges of slate still left un-
eroded on the limestone, in all four counties, it will be
proper to describe the southern edge of the limestone belt,
and show how essentially different it is in Franklin and
Cumberland, from what it is in Dauphin and Lebanon.
The southern edge of the limestone belt in Franklin and
Cumberland counties runs along the foot of the South
mountains to their eastern termination 11 miles west of the
Susquehanna river. Here it turns round the end of the
* It can only be understood by an examination of the colored geological
map of Berks county, made to accompany Report D3, Vol. Ill, which re-
mains unpublished, except as one of the maps in the Hand Atlas Report X.
19
290 GEOLOGICAL SUKVET OF PENNSYLVANIA.
mountain southward and is immediately lost beneath the
Mesozoic Trias red shale.
It is evident that the limestone of eastern Cumberland
county and the limestone of middle Lancaster county are
connected underneath the Trias red shale belt which sepa-
rates them at the present surface by a breadth of more than
10 miles measured along the river.
Whether the Cumberland county limestone and the York
county limestone are also connected underneath the Trias
red shale directly across a distance of 17 miles, is less cer-
tain. The doubt arises from the possible underground con-
nection of the South mountain rocks beneath Dillsburg,
Rosstown and Liverpool with Chiques rock at Columbia.
If such be the case, we must draw the edge of the under-
ground limestone belt from Yellow Breeches creek (2 miles
north of Dillsburg) to New Holland at the bend of the river,
and so on towards Lancaster city.
But, on the other hand, as we do not know what has
caused the depression in which the Trias red shale was de-
posited, we cannot tell how deep it may be ; consequently,
we cannot tell whether or not the limestone in York county
covers the South mountain rocks under the Trias red shale.
The main point is that, when the South mountains come
to an end, the limestone belt becomes covered with Trias
red shale, the north edge of which is of course the south
edge of the surface limestone belt in eastern Cumberland,
across Dauphin and nearly across Lebanon county. Not
until we reach the eastern corner of Lebanon does the south-
ern edge of the surface limestone belt rest again against
South mountain rocks.
Here a small isolated mountain mass called South mount-
ain in Lebanon county and Mulbaugh s Jiill in Berks
county, separates the limestone belt to the north of it, from
the red shale belt to the south of it in Lancaster and Ches-
ter counties.
East of Mulbaugh's hill the red shale laps around and
again covers the south edge of the limestone as far as to
the Schuylkill river below Reading.
East of the Schuylkill river the South mountain gneisses
THE GREAT VALLEY. 291
rise in the range of highlands, with the great valley of lime-
stone at its north foot, and so continues through New
Jersey and New York into New England.
Mulbaugh 's hill at the corner of Lebanon, Berks and
Lancaster counties is therefore an isolated piece of the
highlands about 2 miles broad and 10 miles long, surrounded
on the north by limestone and on the south by red shale ;
but underground no doubt entirely surrounded by lime-
stone ; for the limestone is seen going down under the red
shale at both ends of it ; and there is every reason to believe
that the Trias belt south of it, which is not more than 6
miles broad at the west and 10 at the east, occupies a buried
limestone valley of unknown depth.
We have then in Cumberland, Dauphin, Lebanon and
Berks counties an extraordinary phenomenon, which has a
most important bearing upon the river drainage of the whole
Atlantic coast. The great range of the South mountains
which otherwise extends continuously for many hundred
miles, from its southern end in Georgia to its northern end
in New England, is here broken by a gap 60 miles wide,
I. e. from Dillsburg in York county to Reading in Berks
county. A great gateway through which the greatest river
of the coast (the Susquehanna) drains the back country into
the greatest bay of the coast (the Chesapeake) ; and the
breadth and depth of the bay correspond to the area and
volume of the river, which has been filling it during all the
ages since the Coal. And in this gateway stands a pillar
(Mulbaugh s hill) to mark the continuance of the range un-
derground.
Relation of the South Mountain, uplift to No. II.
Had it not been for this remarkable break in the South
mountain-Blue Ridge-Highlands range of the Atlantic sea-
board region of the United States, it might have been sup-
posed that the limestone formation No. II was deposited in
a sea, the southeastern shore of which lay at the north-
western foot of the South mountain range, then in existence.
But the South mountain range was not then in existence.
292 GEOLOGICAL SURVEY OF PENNSYLVANIA .
The sea extended to that part of the surface of the globe
now covered by the Atlantic ocean.
This fact is made known in several ways : (1) By the
great thickness of the formation at the foot of the mount-
ain range ; (2) by the existence of faults along the foot of
the mountain range ; and of course faults presuppose the
spread of the formation southeast of the faults ; (3) by the
appearance of the limestone formation in valleys between
the parallel ridges of the mountain range ; for such lime-
stone valleys can only represent fragments of the general
limestone outspread preserved in deep troughs ; (4) by the
appearance of the limestone along the southeastern foot of
the mountain range ; as, for example, in southern Berks
and Northampton counties, in New Jersey and New York;
(5) by large areas of the limestone formation between the
South mountain and the present Atlantic coast ; as, for
example, in York, Lancaster, Chester and Montgomery
counties ; but chief (6) by the great expanse of the forma-
tion (both covered and not covered by Trias red shale),
through the 60 mile opening in the range above described,
far away towards Maryland.
The numerous relics of the limestone formation No. II,
preserved as small isolated areas, in southeastern Pennsyl-
vania, taken in connection with the isolated areas remain-
ing in the heart of the mountain range, suffice to prove that
it originally extended in an unbroken sheet, and probably
in a nearly horizontal attitude, over all the United States
and Canada ; and that it probably now underlies the Creta-
ceous and Tertiary belt of the Atlantic and Gulf States, and
perhaps the whole of the Atlantic ocean, the Gulf of Mexico
and the Caribean Sea, covered of course by less ancient
Palseozic, as well as by Mesozoicand Kainozoic formations.
It follows that the uplift of the South mountain must
be later than the limestone and slate formations of the
Great Valley. The date of the birth of the range can even
be fixed with a near approach to truth. Its upheaval seems
to have been in some sense the cause of the folding of all
the formations of middle Pennsylvania of the more gentle
waves in western and northern Pennsylvania, and southern
NewYork, and of the great faults of Virginia and Tennessee.
THE GREAT VALLEY. 293
Now, as these foldings and faults affect the Coal measures
No. XIII at the top of the series, just as seriously and in
precisely the same manner as they affect the lowest forma-
tions of the series, the sandstone No. I, the limestone No.
II, the slate No. Ill, the sandstone No. IV, &c.,' the fold-
ing action must have taken place after the Coal measures
had been deposited. On the other hand, the Mesozoic
(Trias) red shale formation next following in age the Coal
measures lies quietly, as we have seen, over the upturned
edges of the older series, and therefore the folding action
must have begun and ended in the interval of time between
the deposite of the last Coal measures (Permian of Green
county) and the first or bottom beds of the Mesozoic strata
which we see lying sometimes upon the gneiss, sometimes
on No. I, sometimes on No. II, along a line east and west
of Norristown in Montgomery county and elsewhere.
If the folding action was produced by a push of the whole
Atlantic coast region northwestward as it evidently was
for there is a general overturning of the tops of the folds in
that direction the push must have been connected with
the rise of the whole range of the South mountains from its
northern to its southern end ; for the folded country is a
thousand miles long by five hundred broad ; and the im-
mense height of the upfolds (anticlinals) and. depth of the
downfolds (synclinals), amounting variously to 5 miles
vertical, shows that nothing less happened than a shifting
back of the whole Atlantic belt of the earth's crust north-
westward a distance of at least 4.0 miles.
The mountains thus created were evidently as grand as
any more recently produced in any part of the world, the
Andes and the Himalayas for example. But these consist
of the last deposits of the ocean, and have so lately ascended
into the air that, although their destruction is going o n
with great rapidity, many of their summits are still more
than five miles high. Whereas, a like process of destruc-
tion has been diminishing our old Pennsylvania mountains
for many geological ages, so that not a trace is left of their
original magnificence ; the edges of a few of the harder
formations make continuous ridges and these not more than
1000 or 2000 feet above the general surface of the low lands.
294 GEOLOGICAL SURVEY OF PENNSYLVANIA.
CHAPTER XXIII.
Why is- there no coal in the Great Valley f
The answer to this often asked question is easy, short and
practical : No coal beds can be found in the Or eat Valley
because the Coal Measures which once covered the region
have all been swept away into the Atlantic Ocean.
The geological structure of the Great Valley, taken as a
whole, is simple and easy to understand. It has large
features not to be misunderstood ; in fact visible at a glance
upon the colored geological map of the State, where a band
of blue (limestone) and a band of gray (slate) run side by
side its whole length across the State.
I will recapitulate in a few short sentences the principal
points of the last chapter so that they may be kept in mind.
1. The South Mountain sandstone (No. 2) is older than
the limestone formation in the valle} 7 , and passes down
under it to make a foundation for the whole valley and for
all Pennsylvania, New York and Ohio to the northwest of it.
2. The limestone strata (No. II.) are older than the slates
of No. Ill, and of course underlie the slate belt ; except
where the slate belt is thin and worn away, letting the
underlying limestone appear in the coves. The whole lime-
stone belt was once covered by the slate formation. As the
cleaning away of the slate from off the limestone belt has
been always going on, and is still going on, only isolated
patches of the lowest part of the slate formation remain
here and there on the limestone belt.
3. The slate formation (No. III.) is older than the North
mountain sandstone and passes under it northward.
4. The North Mountain sandstone (No. IV.) descends in
its turn, northward, beneath the formations of Pike, Monroe,
Carbon, Schuylkill, Perry and Fulton counties.
We shall see in succeeding chapters how formations II,
III, IV rise several times to the surface in middle Penn-
sylvania ; every time making a limestone valley surrounded
THE GREAT VALLEY. 295
by a slate belt and by a mountain like the North mountain.
Then we shall see them plunging vertically to a great depth
beneath the Allegheny mountain, along the top of which
runs the first bituminous coal basin. Here we see all the
formations from IV to XIII piled upon them. In Huntingdon
county all the formations from IV to the Broad Top Coal
measures (XV) are piled upon them. Even close by the Great
Valley, in Dauphin, Schuylkill and Carbon counties, all the
formations from IV up to the top of the Anthracite Coal
measures (XVII) remain piled upon them ; the limestone
No. II lying at- the enormous depth of 30,000 feet beneath
the city of Pottsville.
Just as we see along the Little Juniata all the formations
from XIII in the Allegheny mountain to IV in Bald Eagle
mountain rising (southeastward) one after the other to make
an arch h've miles high in the air over the Nittany limestone
and slate valley, and then descending (southeastward) one
after the other in Tussey and Terrace mountains beneath
the Broad Top coal field just so we see the whole pile of
formations from XII to IV coming straight up from the
underworld in the Sharp mountain, Second mountain and
North mountain to make a similar great arch in the air over
the slate and limestone belt of the Great Valley .
But as the great arch over Nittany Valley has all been
swept away, and it is useless to seek for coal at the present
surface anywhere between the Cambria and Clearfield coal
mines and the Broad Top coal mines, so the arch over the
Great Valley has been swept away and it is useless to seek
for coal south of Sharp mountain in Schuylkill and Dauphin
counties.
The coal measures have been swept away from the Great
Valley many geological ages ago ; and we know by long
experience that there are no workable beds of coal in any
of the pile of formations beneath the coal measures, except
one bed in No. X at Duncannon, and that is worthless,
and has been swept away (with the rest of the rocks) from
the Great Valley.
To illustrate what has been stated above in a few words
I insert two cross sections which will speak to the eye better
than any words :
296 GEOLOGICAL SURVEY OF PENNSYLVANIA.
Section through Harrisburg (page 277, plate 2) from Dun-
cannon at the mouth of the Juniata, down the Susquehanna
to Columbia ; and
Section across Franklin county (page 281. plate 4) from
Path Valley mountain, through Scotland to the South
mountains.*
The practical importance to the farmers of the Great
Valley of knowing these facts and understanding the above
statement is evidently considerable. Why should they
waste time and money in digging for coal where it cannot
possibly exist ?
There is not a trace of a coal bed left at any point in
any county along the whole course of the Great Valley
between the Hudson and the Potomac; nor in Amberson's
valley and Path valley which lie behind the North mountain
in Franklin county ; nor in the Fishing creek Trout run
Pine Grove valley in northern Dauphin and Lebanon
counties.
All reported discoveries of coal beds are mistakes which
a few words will suffice to explain.
Along the center line of the Great Valley, between the
limestone belt and the slate belt, the black Utica slate
formation, Ilia, crops out, always thin, and often absent.
In other words, the bottom rocks at the southern edge of
the slate belt are often as black as the black slate of a coal
bed, and have deceived many persons into digging for coal.
When weathered down they make the jblack clay which is
so conspicuous in the great Ironton iron mines of Lehigh
county, and the Moselem mine of Berks county. They
make a black soil at other places along the lines of junction
of the slate and limestone lands. But no impressions of
coal plants are ever seen in these Utica black slates. But
occasionally impressions of graptolites may be observed on
them, looking like lead pencil marks on paper; some of
them are merely forked lines ; some of them look like the
* These sections have been carefully constructed on a scale of 4 miles to 1
inch from observed outcrop dips in the Great Valley and to the north of it
so numerous that no material error can be imagined in the general shape of
the arch in the air over the Great Valley.
THE GREAT VALLEY. 297
edge of an open umbrella ; others like holly leaves. They
are the remains of curious little animals which swarmed at
the surface of the ancient sea ; and they were. so numerous
that their dead bodies darkened and even blackened the
mud which afterwards was hardened into slate rock. These
graptolite slates are exposed to view in the horse shoe bends
of Connedogwinnet creek in Cumberland county.
Discoveries of coal are reported from time to time by
people living in front of tJie North mountain, on its foot
slopes. Pieces of so called coal are frequently found lying
on the surface or are knocked out of the exposures of dark
slate ; for example, near Mercersburg and London in Frank-
lin county. But these pieces are not indications of the
existence of a workable coal bed. They are merely black
shale layers in the upper part of the slate belt (Hudson
river slate formation Illb,} charged with the animal
carbon of dead graptolites and trilobites (water bugs) which
lived in immense numbers in the waters of that age.*
Discoveries of coal have also been reported from behind
the North mountain in Lebanon county, along a narrow
belt of the Marcellus formation (VIIK) which runs entirely
across the state into the southern states, and zigzags through
many of the valleys of our middle counties. It is a narrow
belt of outcropping black-slates very much resembling the
black-slates which cover coal beds in the coal regions. But
it is slate and not coal. People who see it in a hillside in
the form of a regular bed, and very black, looking a good
deal like the outcrop of a coal bed, think that it is merely
the bad edge of a good coal bed. They who try to burn a
piece of it in a blacksmith's fire find that it will blaze a
little at first and then remain red hot and throw out a good
deal of heal;; but when they take the piece out of the fire,
it is nothing but a stone. This however does not discourage
them ; there are plenty of wandering miners seeking a job
who assure them that if they will "go down on the bed" it
will turn to good coal. In almost every county in the. state
* The chemical analysis of a specimen of this deceptive kind of coal, found
back of Mercersburg in Franklin county, will be given in a subsequent
chapter, where the rocks of the slate belt are described.
298 GEOLOGICAL SURVEY OF PENNSYLVANIA.
lying between the North mountain and the Allegheny
mountain considerable sums of money have been wasted in
sinking shafts and drifting tunnels into this belt of Mar-
cellus black slate during the last fifty years, but no valuable
coal bed has ever been obtained.*
CHAPTER XXIV.
The Great Valley Limestone No. II.
Having described in the last chapters the general topo-
graphical and geological features of the Great Valley, I
shall give in this and following chapters descriptions of its
two principal formations in sufficient detail to make them
understood : (1) the limestone beds in the Lehigh region ;
the quarries between the Schuylkill and Susquehanna ; the
quarries west of the Susquehanna ; (2) the slate belt with
its roofing slate quarried in the Lehigh region ; and its
clay-limestone beds on the Susquehanna.
The reader will thus be prepared for a description of these
formations where they have been preserved in synclinal
basins in Chester, Lancaster and York ; and where they are
brought up to the present surface by anticlinal waves in
Fulton, Perry, Juniata, Mifflin, Bedford, Blair, Hunting-
don, Centre, Clinton and Lycoming counties.
The exhibition is so great, the wealth of observations so
over-abundant, that the most condensed summary of the
facts published in the reports of the survey will seem to
need ,ome apology for its length. But it is an embarass-
* In Perry and Juniata counties thin streaks of very slaty Marcellus
coal cross the bed of the Juniata river, and much money was formerly
wasted in following them into the hillside ; all money thrown away.
Peoples' experience of Marcellus black slate mining in other states has
always been the same. I have added this instance of deceptive coal pros-
pecting, because it is of importance to the citizens of Lebanon and Dauphin
Bounties in the Great Valley. It will find its place again in a future chapter
on the Marcellus formation.
THE GREAT VALLEY. 299
ment of riches. I can only strive to classify the subjects
.properly, and avoid repetitions.*
Subdivision of No. II.
In New York state No. II is subdivided into (1) Trenton,
Black river and Bird? s-eye limestone at the top ; (2) Chazy
limestone in the middle ; and (3) Calciferous sandstone at
the bottom, resting on the Potsdam sandstone, f
In Pennsylvania along the Great Valley belt the only
distinct division of it that can be made is into upper purer
limestone beds, ancj lower magnesian cherty and sandy beds ;
that is, if the New York names are to be used, into Trenton
limestone on top, and Calciferous sandstone for all the rest
of it down to the bottom 4
*The detailed descriptions of quarries may seem needless ; but they are
only specimens on a large scale of the economical geology of the state, and
teach the structural geology in a better manner than it could be taught by
verbal general statements. It is a kind of object teaching. It shows the
difficulties and the successes of field work. It points out localities for study.
Above all, it has a business value. The quarries of the Great Valley are
selected because they are a numerous, connected and tj'pical series, and
have played a master role in the history of the growing wealth of Pennsyl-
vania.
fThe discussion on the "Quebec group" of the Reports of the Canada
Survey do not concern us in Pennsylvania ; but any geologist who desires
to know the last word on it will find, it in two short communications in
Science, Dec. 26, 1890, page 359 ; one by R. W. Ells, repeating his opinion
(published in the Canada Survey Report of 1887-8, pp. 83, 84, K) viz.: "That
these [Quebec] rocks represent a peculiar development of strata of Trenton
age, and probably even down in that formation," sustaining Logan's old
view ; the other, by Alfred R. C. Selwyn, the Director of the Canada Sur-
vey, opposing W. Ami's views, and repeating his own opinion (as against
Logan) published in 187(>-7, that the Quebec city rocks are certainly of Hud-
son river (Lorraine, Cincinnati) age, overlying the Trenton. I may be per-
mitted to add here that neither my conversations with Logan while he lived,
nor the study of his written statements of the case, removed my objections
to what I regarded his extraordinary and improbable theory of an expan-
sion of a part of formation ^o. II eastward into a great local formation
named by him "the Quebec group."
f Writing of the magnesian part of the formation in the Lehigh region, Prof.
Prime says : " Lithologically it seems to be impossible to make any distinc-
tion between the limestones which must belong to different geological hor-
izons ; for limestones from the top of the series, close to the Trenton lime-
stone, look quite as much like those from just above the Potsdam [C'hiques]
300 GEOLOGICAL SUEVEY OF PENNSYLVANIA.
Even in the back valleys of Middle Pennsylvania no
better sub-division of the whole formation can be made ; .
although the unbroken, uncrumpled condition gives a
chance to put its beds in vertical order which is not possible
in the Great Valley. For we there see only a gradation
from the purer beds at the top downward into middle cherty
beds and lower sandy and cherty beds, without any strongly
marked general horizons of change.
Prof. Stevenson's railroad section of 4519 feet of it in
Bedford county, Snake Spring township (Report T2, p. 93)
will illustrate the fact.
420' of Trenton blue flaggy limestones, He; succeeded
downwards by thicker beds of light blue or bluish grey ;
mostly not silicious ; many yielding superior lime.*
1351' of Chazy beds, in part 116 ; highest beds hardly
silicious ; white chert balls begin to appear (descending)
600' below the top ; next 400' cherty limestones ; further
down more and more silicious ; black chert appears at 1200'
from top ; streaks of chert so numerous that the weathered
surface is fretted with ridges. f
420' of concealed measures.
419' of limestone, mostly silicious.
400' (estimated) concealed measures.
175' (exposures imperfect) limestone, silicious.
150' concealed measures.
300' (Calciferous in part, Ha) beds of cherty calcareous
grit ; fretted weather surfaces show the abundance of thin
'chert layers.
90' concealed measures.
sandstone (No. 1) as do specimens taken from two beds in the same quarry
not ten feet vertically apart. No traces either lithological or palseontological
have been found by which the Calciferous sand rock (said by Rogers to occur
near Easton) can be recognized or differentiated from the other formations."
(Report D2, page 11.)
*The line of separation of the Ulica slate No. Ill from the underlying
Trenton limestone No. II, is almost abrupt where well seen in Milligan's
Cove (T2, p. 93). Fossils rare; Calymene senaria and Strophomena alter-
nata, obtained from one of the highest beds. Columnaria alveolata was
seen in Morrison's cove (p. 94).
f Cyathophylloid fossils got near the base of this subdivision along the
Juniata.
THE GREAT VALLEY. 301
620' of limestone beds sandy but with very little chert ;
most of them might be called a calcareous sandstone.
175' concealed measures Total, 4519 feet.*
No one can doubt that the uppermost beds of the lime-
stone belt represent the Trenton outcrop on the Mohawk
river. We can therefore safely use that term in Pennsyl-
vania; and typical Trenton fossils occur in sufficient numbers
to justify its use.
Chazy fossils occur sparingly in the middle magnesian
beds, and I see no objection to retaining that name.
But Calci/erous sandstone was from first to last an un-
fortunate New York term and ought to abandoned. The_
beds are limestone, riot sandstone beds, although they are
often sandy, and have an abundance of silica in the form
of chert ; but many of the lowest beds are nearly pure
magnesian limestone, layers. f
CHAPTER XXV.
No. II in the LeMgh region. $
The beds of limestone along the Lehigh river, where they
have been exposed to special view in very extensive quarries
worked for the Allentown, Crane and Thomas furnaces, are
seen to vary much in texture, color, hardness, structure and
chemical composition.
Some beds are compact, others crystalline.
Blue and dove colors prevail ; but some beds are almost
white, others nearly black ; and the blue limestones are of
all shades from lightest to darkest blue.
* It is quite probable that towards the northern edge of Bedford county a
greater thickness of this formation is brought to the surface ; but no details
were obtained there. (T2, p. 94. )
1 1 am unwilling to add another name to our already copious nomenclature
by calling them the Allentown, or the Easton, or the Reading, or best of all
the Bethlehem formation, which last would be unexceptionable, if distinct
limits could be assigned to it, which cannot be done. I prefer therefore to
distinguish vaguely the lower, middle and upper portions by the old num-
bers, Ha, life, He.
JI take the substance of this chapter from Prof. Prime's report, D, D2, D3.
302 GEOLOGICAL SURVEY OF PENNSYLVANIA.
The hardest beds are commonly those of dark blue color ;
others are soft, disintegrating to | or % of an inch on a
weathered surface so that they can be rubbed to loose sand
between the fingers. Groups of the harder beds make little
ridges which determine to some extent the direction of
brooks and streams on the surface.*
The softer beds give lines of sink-holes leading down to
caverns through which subterranean streams flow, some-
times reappearing at the surface in large springs, at other
times emptying into the larger river valleys. Many of the
longitudinal vales are ancient caverns which have lost their
roofs.
Two different kinds of structure are well known to the
farmers : rock limestone and slaty limestone. The massive
beds of rock limestone are accounted to make a better farm
lime, or stronger manure ; and this is probably a correct
opinion, for the slaty limestone owes its structure to its greater
percentage of silicate of alumina, which does not act as a
manure. Some very pure lime or lime-magnesia (dolomite)
beds with a very slight percentage of silica are extremely
thin-bedded, slaty looking, and ringing when struck. Some
shaly beds have so large a percentage of alumina that they
decompose to clay.
A very strange, peculiar and entirely mysterious feature
of some beds is a structure resembling a mass of clam shells
closely packed together with their round sides uppermost.
The chemical composition varies between a pretty pure
carbonate of lime, and a nearl}'- correct dolomite (half lime,
half magnesia), but always with some amount of silica,
alumina, iron, phosphorus, carbon and water of crystalliza-
tion. And it seems that the lower (more southern) beds of
the formation are more magnesian (on the whole) than the
upper (more northern) beds.f
*Well exemplified in the steep bluff of hard limestone, bounding the
Jordan, | m. N. W. of the Thomas I. Co.'s mine, No. 149 of the map. Ex-
tensive quarries of good curbing and crossing stones are worked on the N.
bank of the Jordan, f m. E. of Orefield.
f Such is the opinion of Prof. Roepper of Bethlehem, and Mr. W. Firm-
stone of the Glendon I. Works, whose analyses have been numerous and
intentionally directed to the discrimination of the beds as fluxes. It is cer-
THE GREAT VALLEY. 303
The dolomite beds, however, are distributed among the
limestone beds in a curiously capricious manner, showing
no kind of order or system anywhere throughout the form-
ation.* This is the case high up in the series ; as appears
from analyses of 10 of the beds of Grove quarry in Black
Log Valley, made for Orbisonia furnace in Huntingdon
county ; where the Trenton formation is exposed, about
500' thick, dipping about 60, and composed of dark blue-
and gray soft argillaceous limestones alternating with blue
lime shales (more abundant toward the top); the quarry be-
ing opened in lower beds, measuring 22, 20, 10, 24, 18, 21,
20, 32, 30, and 72 inches thick respectively ; and the re-
spective percentages of carbonate of lime being (in whole
numbers) 90, 85, 90, 74, 81, 83, 81, 82, 85, 47, the last and
lowest a dolomite. (F, p. 260.)
Damourite (hydromica) layers only half an inch or more
in thickness part the limestone beds from one another all
through the formation, and in such numbers that a hun-
dred of them have been counted in a single outcrop. They
are regularly interstratified with the limestone beds, and
are decomposed by the weather into clay.f
But the damourite is sometimes seen as leaves thinner
than paper, completely intermingled with the limestone and
so thoroughly incorporated as to make a separation of the
two impossible. The flakes of the mica in this latter case
cross the body of the limestone in all directions.^
tain that the cement beds, so rich in alumina, are at the top of the magnesian
series, or in the Trenton formation II c.
*Of this more will be said in describing the McCormick quarries at Har-
risburg. Here I will merely give Mr. J. B. Britton's analyses of viine beds
in Troxell's quarry, Jordan Bridge of the C. <fe P. R. R. ; A. the lowest bed ;
I. the highest ; A. to E. worked for flux for Crane I. C. furnaces, F. to I. re-
jected.
Garb, lime, 85.2,76.8,78.2,61.5,70.1,63.9,71.9,58.3,89.5;
Garb, mag., 5.9,17.0,14.5,26.8,20.1, 3.1, 8.3, 2.3, 0.6;
Silica, 7.1, 4.1, 4.7, 7.3, 6.1,27.7,14.6,33.2, 8.2.
For the percentages of phosphorus, alumina, iron, etc., and for many
other similar limestone analyses, see Prime's Report, D2, 1878, page 16 to 20.
f Hydromica is a hydrous silicate of potash and alumina.
J Prof. Prime adds that this may excite a suspicion that the damourite has
been a subsequent production, although the limestone rock is fresh and hard
and shows no sign of water percolation, or mineralogical change of any
394 GEOLOGICAL SURVEY OF PENNSYLVANIA.
The great mass of damourite slate (primal slate) at the
bottom of the formation, with its line of limonite iron ore
banks, has been described in a previous chapter. A large
quantity of damourite slate appears at the top of the forma-
tion also in some places along the line of contact with the
slate belt ; and in this upper outcrop occur the great limo-
nite mines of Ironton in Lehigh county, and Moselem in
Berks county ; also as I believe, the Corn wall magnetic iron
ore mine in Lebanon county ; and the Path Valley limonite
mines in Franklin county.*
Cliert is abundant in the lower portion of the great lime-
stone formation No. II, both in scattered balls, and in lens-
shaped masses. The chert is sometimes honeycombed, or
contains cavities from which rhombohedral crystals of dolo-
mite have been dissolved out.
Sandstone beds are sometimes met with between the lime-
stones ; and they help much to prove the mechanical deposit
of the whole formation. A few only have been noted; the
largest not 2' thick ; all in the magnesian beds ; and all in
company of damourite ore bearing slates. f
kind. To my mind it is only another proof that the limestone was not a
chemical precipitate, but a regular mechanical sediment ; and that the rivers
which brought the sediment to the sea carried large quantities of floating
flakes of mica from some mica schist region ; sometimes spread the mica
flakes when most abundant in thin layers ; at other times when less abund-
ant the mica flakes would slowly settle singly to the bottom and stand or lie
as they happened to touch bottom. A typical locality for this exhibition is
the limestone exposure in the bottom of the Ironton R. R. Co.'s iron mine.
*It has been already said that some, if not many, of the smaller limonite
banks of Northampton and Lehigh. county, located in the middle region of
the limestone belt, may have been produced by damourite slate partings in
the middle of the formation. But many more of them are connected with
synclinal folds in which the slates of III have once lain, but are now swept
away ; these mines must be referred then to the damourite slates at the top
of II. But see a subsequent chapter for reasons to modify this statement so
as to make it refer to the top of the magnesian limestones and not to the top
of the Trenton.
f Instances are : A sandstone bed 19 inches thick, cut by the L. & S-
RR. just west of the round house at Bethlehem ; quite conformable ; lower
9" a pure quartzite ; upper 10" more of a conglomerate of quartzite with some
limestone ; evidently a breccia of two adjoining beds produced by pressure.
(D3, p. 172.) A thin bed of saccharoidal sandstone at the Breinig mine
between Trexlertown and Breinigsville ; analysis showed quartz, with small
quantities of damourite ; evidently a sandy layer in the ore bearing potash
THE GREAT VALLEY. 305
Oolitic lime stone beds are frequently encountered, but not
confined to any fixed horizon in the series ; no use can be
made of them by the field geologist in establishing the order
of the beds ; for they are very local and irregular, the
oolitic character often disappearing from a bed only a few
feet from where it is strongly pronounced. The round grains
are generally a little larger than sturgeon's roe ; sometimes
loosely scattered through a crystalline limestone ; at other
times so abundant that there is hardly room between them
for the cementing paste.*
Breccia beds. It frequently happens that one limestone
bed lying between two others is a sort of conglomerate, but
differing from pudding stone conglomerates in two features:
(1) The fragments are all and always angular, sharply
angular, and not rounded or rolled in water ; (2) These
angular fragments are not composed of various kinds of
rocks, but are all limestone, and all of the same sort of lime-
stone, whether more or less magnesian ; (3) These beds
moreover are to be met with in all parts of the limestone
belt, from the bottom magnesian beds, to the top non-
magnesian beds. It is evident then that such beds are not
of the nature of gravel conglomerates formed on ancient
shores by the action of waves ; but that they are breccias,
that is, broken-up or smashed layers of limestone, crushed
by the pressure force of an earth movement from the south,
the fragments of the bed remaining in their places, and
being afterward cemented together by percolating lime
waters depositing calcite.f
slates. (D, p. 34.) A. similar layer, only one inch thick, occurs in the ore
slate of the Schwartz and Fogel mine. (D, p. 36.) A bed of sandstone 5"
thick is interstratified in the quarry next but one to the Brewery on the
Delaware; and another 5" to 8" thick in the quarry next the Brewery, in
company with thin beds of damourite and an oolite limestone. (D3, 171.)
* The fish-roe grains of oolitic limestone have been usually explained as
grains of sand around which the carbonate of lime has concreted itself.
Recently it has been proven by the microscope that some limestones, if not
all of them, are made oolitic by rounded fragments of fossil bryozoa. They
are apparently the lime mud of destroyed coral reefs in which lie enclosed
small bits of coral rounded by the waves but not reduced to mud.
t Prof. Prime notes, as typical localities, Mary Kohler's quarry m. W.
of Whitehall station (L. V. RB.), and an exposure on the Jordan just N. of
Helfrich's spring. (D2, p. 13.) He gives an analysis of the M. Kohler
breccia on page 15.
20
306 GEOLOGICAL SURVEY OF PENNSYLVANIA.
Cement beds occur somewhere in the Trenton limestone
(// c), along the edge of the slate belt, which crosses
the Lehigh river at Coplay. Here are the quarries of the
Coplay Cement Works, and of the Lehigh Cement Works
on the west bank ; and the quarries of the Old Lehigh Ce-
ment works and of the Allen Cement Company on the east
bank. They are traceable westward to the Ironton * mine in
Lehigh county ; and eastward all along the road from Sieg-
fried's Bridge to Nazareth in Northampton county ; and
again in the neighborhood of Martin's Creek village at the
Delaware, f A subsequent chapter will be given to these
cement beds, their quality and use.
The folded stratification of No. II.
The limestone quarries along the Lehigh show the folded
and compressed condition of No. II ; and yet much of it is
seen to be less complicated than was formerly supposed ;
merely lifted and thrown into waves ; as for example in
the Lehigh Valley Iron Co.'s long quarry at Coplay, the
north end of which shows two short sharp little upfolds
disturbing an otherwise almost horizontal outspread.:}:
The prevalence of cleavage planes, generally sloping
southeast, obscures the stratification, and sometimes almost
obliterates it. Sometimes it is impossible to read the dip,
the beds being broken up into a mass of blocks of irregular
shape.
While the majority of the dips are towards the south,
*D2, p. 57, 58. Dr. Genth's analysis of a sample from here reads : Garb,
lime, 82.05 ; insoluble silicates of alumina, etc., 15.07 ; ferrous and mang. car-
bonates, 0.09; carb. magnesia, 0.17; water, 2.42; carbon and undetermined
matter, 0.20.
f D3, p. 164.
\ See the beautiful photo-lithograph picture in D2, plate 2, p. 54. The south
end of this quarry, on the contrary, shows the limestone beds thrust up
suddenly into a vertical attitude, and then turned sharply over in a larger
anticlinal with a squeezed top. (See plate 1 in the same report D2.) What
is exceedingly interesting, one of the upfolds in plate 2 is crossed on top by
horizontal beds, proving the great amount of slip and slide of bed on bed
which took place during the movement.
As in H. Stein's quarry 2 m. S. W. of Fogelsville, a picture of which is
given in report D, p. 9 ; also the Hokendauqua quarry close to the L. V. R. R.;
the Coplay quarry ; and those just outside of Catasauqua (D2, p. 54).
THE FOLDED STRATIFICATION OF NO. II. 307
there are many exposures of north dips, but not enough to
account for all the south dips ; consequently many of the
south dips must be overturns ; and this is proven by over-
turned compressed anticlinal folds exposed in the quarries
along the Lehigh river.*
The magnesian limestone lowest beds are said by Prof.
Prime (D2, p. 55) to be always conformably superimposed
upon the Chiques ("Potsdam") quartzite, even when the
latter show steeper dips than those of the neighboring lime-
stone beds.
The Trenton limestone uppermost beds also, as a rule,
conformably underlie the slate beds of No III ; although in
some places both are seen inverted so as to place the slates
underneath the limestones. f
Fossils in Lehigh county are very rare in the limestones;
too few to serve the palaeontologist who wishes to use them
for subdividing the whole into formations of separate ages.
A Maclurea, and some cross sections of EuompTialus
(species unknown) were first found in a quarry 2 m. E. of
Ballietsville, indicating the Chazy age of the beds. Then
three casts of Monocraterion (worm burrows) were found in
the bed of the Jordan, just W. of Helfrich's spring.:}: A
dozen specimens of Lingula (species unknown) were found
in Schadt's quarry, m. N. W. of Helfrich's spring. A
*One such at Catasauqua passes through a hill and is quarried on the east
and west sides of the hill. The two sections of the arch thus made were
photographed and lithographed for plate 3 (Rau's quarry) and plate 4
(Weaver's quarry) in Prof. Prime',s report D2. The slip and slide of the
beds on one another in the pinch of the arch is finely shown in Rau's quarry.
fThe anticlinals and synclinals of Lehigh county are located and de-
scribed by Prof. Prime in D2, pp. 55 to 57.
\ Here is a cave and a water sink. Prof. Torell indentified these casts as
belonging to his Swedish Cambrian genus; the name M. lesleyi, will prob-
ably be abandoned for Scolithus, as the funnel-shaped end of the cast is
often seen in the Cambrian Scolithus. (For figures and description see
Appendix to Report D2, p. 80.) But the presence of this fossil cast is no
evidence of the Cambrian age of the magnesian limestone beds. As Prof.
Prime says in his summary of evidence of their Chazy and Calciferous age
there is no sign of a stiatigraphical break in the series from the top of the
acknowledged Trenton beds to the bottom of the Magnesian series. " There
is not a particle of evidence that any of these limestones belong to Huronian
(as suggested by Dr. T. S. Hunt) or older epochs ; all the facts point the
other way." (D3. p. 163.)
308 GEOLOGICAL SURVEY OF PENNSYLVANIA.
poor fragment of an Orthoceras was found in a loose rock
1000' N. of the tavern at Scherersville.
Fossils in Northampton county have been got from the
middle and upper limestones ; thus Maclurea (or Euom-
phalus] in Dech's quarry, \\ m. S. W. of Bath ; probably
of Chazy age. Encrinal stems, not far N. E. of last;
Trenton age-, also abundant in the upper beds of Krock's
quarry at Christian spring ; also, from there eastward to i
m. E. of Nazareth, wherever the limestones are weathered;
also, in Russ' quarry, just S. W. of Nazareth (here in com-
pany with a few Orthis testudinaria); also, on Knecht's
farm close to Bushkill creek, m. S. W. of Stockertown
(here in company with Ohcetetes lycoperdon and 0. testudi-
naria}; also, at quarry opposite Churchville church, in
upper weathered rocks (the lower beds affording Leptcena
sericea, 0. testudinaria, and 0. pectinella); also m. E. of
Kellers tavern (two or three encrinal outcrops). All these
exhibitions prove that encrinal stems mark theTrenton out-
crop. In the quarries on the Delaware just S. of Ho well's
cotton mill are found Leptcena sericea, Orthis pectinella,
O. testudinaria, Strophomena alter nata, Chcetetes lycoper-
don. and one or two other undetermined forms, lying in
colonies of from 20 to 200 individuals, and not scattered
through the rocks, which are evidently of Trenton age.
GREAT VALLEY LIMESTONE QUARRIES. 309
CHAPTER XXVI.
Limestone quarries of tlie Great Valley between the Schuyl-
kill and the Susquehanna rivers.
Looking from the car window of a train moving westward
from Reading towards Harrisburg a geologist is struck with
the remarkable fact that the limestone beds cut by the line,
or exposed in quarries within his view, seem to be all
dipping southward, and usually at low angles.*
But after passing Myerstown station, a broad flat plain
of limestone or shale begins to spread out south of the rail-
road, showing few exposures of any kind. At Lebanon,
across this plain runs the branch railroad to the Cornwall
iron mines, and along this railroad quarries and natural ex-
posures show the limestone formation, lying comparatively
flat ; that is, rolling with gentle north and south dips ; the
last south dips sinking beneath the Cornwall trap dyke.
South of the dyke the lime shales at the top of the forma-
tion dip S. and are cut off by the great Cornwall fault, their
edges abutting against the downthrown edges of the trias.
* Thus approaching Wernersville station the dip is 10 S. Great quarries
opposite the station show the same. Passing the station the same dip ap-
pears at the creek. Approaching Robesonia station the dip is 20 S. Beyond
that station is a fine quarry with dips of 20 S. Here a branch RR. runs
south up a little valley between highlands to Robesonia furnace. The hill
W. of the furnace is perhaps 500' high ; a long gentle slope of limestone
descending to the railroad ; the slope from the foot of the hill to the railroad
at Womelsdorf station is half a mile wide; dip at "the station 5 N. (?);
beyond the station, 30 S. Most of the line between here and Richland
station is through slaty, thin-bedded limestone beds all dipping gently S.
but at one exposure 30.
Slack slates make a great show in the cut east of Richland station.
Curiously enough the fields to the south expose ribs of limestone striking
N. and 8.; and in a second black slate cut, west of Richland station, there is
an anticlinal roll striking also N. and &. but much crushed and contorted.
Further west dark limestone and slate dip 10, W. of S. Still further on,
approaching Myerstown station, are more fine cuts in dark slate dipping
10 south.
310 GEOLOGICAL SURVEY OF PENNSYLVANIA.
In spite of the general flatness of the limestone of the
Lebanon plain, there are plenty of contortions, rolls, steep
dips and probable overturns in the quarries around the city
of Lebanon, and up to the south edge of the slate belt,
which is itself greatly compressed and crumpled with over-
thrown south dips.
From Lebanon to Harrisburg S. dips prevail both in the
limestones and in the slates ; and of course more than half
of them must be overturns ; for the two great formations
as a whole are descending northward to profound depihs
beneath the Anthracite coal basins of Schuylkill county.
And the same state of things obtains west of the Susque-
hanna river all the way to Maryland and Virginia.
In the following description of the quarries it will be
noticed that the southward dips vary between S. E. and S.
West. This shows that the pressure has operated in all
directions, subjecting the stratification to all kinds of
irregularities ; often so excessive as to swing the dips round
to east and west, that is directly across the strike lines of
the valley. For instance, on the east side of the Schuylkill
at Reading, the dips are due east, or towards the mountain
back of the city. On the west side of the river they are S.
E.; further west they are S.; still further west S., S. W.
and sometimes even west.*
That the south dips are sometimes normal and sometimes
overturned is not a matter of theory. In Brinkley and
Zinn's quarry at Wernersville can be plainly seen a fold
thrown over to the north, the beds on both sides of it dip-
ping 45 S. 20 W. the fold being tightly compressed. An-
other fold, not quite tightly compressed, but overthrown to
the N. 40 E. is visible in Goul's quarry, 2 m. W. of Wer-
nersville. Another is seen in Donges' quarry at Myers-
town, Lebanon county, in the laminated lime slate beds
dipping to the eastward, the fold being pushed over to
the west.
Other evidences of the generally folded, compressed and
overthrown condition of the whole formation would appear
* Supposing a N. and S. fault at Reading, which is not probable, the fault
line 4 projected southward would strike the trap mountain W. of Birdsboro'.
BERKS COUNTY QUARRIES. 311
in the quarry faces were it not that the excavations usually
follow the outcrop lines of such beds as are of superior
quality, and seldom cut across a series of folded strata.
In the following condensed description of the limestone
quarries of the Great Valley in Berks, Lebanon, Dauphin,
Cumberland and Franklin counties, between Reading on
the Schuylkill river and Mont Alto near the Maryland state
line, I make use of the elaborate notes of Mr. E. V. d'lnvil-
liers, published in the Annual Report of the Progress of
the Survey in 1886, part IV, pages 1517 to 1562.
Berks county quarries.
FrilV s quarry, at the west end of the Lebanon Valley RR.
bridge over the Schuylkill river at Reading ; large, excel-
lent for building, curbing, or paving ; quarry beds good and
regular for 60'; dip regular 40, S. 30 ^.Another, 1000'
S. of bridge, rich, dark blue, good building stone ; 2200
perches per year, at 40 to 60 cents a perch ; dip 40, S. 25 E.
DrexeT s quarry, near the last; occasionally wrought ;
beds, V to 4' thick ; easily quarried and handled ; dip, 40,
S. 20 E.
Gudlirts quarry, 1$ m. W. of Schuylkill, small ; aban-
doned ; dip steep, S. E.
Private quarry of thin lean beds, 3 m. W. of river ;
abandoned.
DeckerV s quarry, Sinking Springs, poor, abandoned ; dip
irregular 35 to 50, say S. 25 E.
Pfeifer's quarry, near last, abandoned like the others
because the lean stone is neither fit for furnace fluxing nor
lime burning. Dip obscure, probably S.
HuyetCs quarry, on the turnpike, 1 m. W. of Sinking
Springs ; large, abandoned ; lean, hard, dark blue-gray,
beds alternately thick and thin (slaty), all dipping 30,
southward, and much cut up with cleavage planes.
Evans' quarry, on RR. i m. west of Columbia Branch
junction (1 m. W. of Sinking Springs); large, old, aban-
doned, beds not pure, dip 40, S.
Ruth's quarries (two), on Columbia branch RR. No. 2
furnished flux for Birdsboro' furnaces ; dip 35, S. No. 1
312 GEOLOGICAL SURVEY OF PENNSYLVANIA.
sent flux to Reading furnace ; light blue, lean, quite thin-
bedded, dip 40-45, S. 15 E.
Ludwig's quarry, S. W. of last; 3 kilns; 500 bushels
per week ; home market at 7 cents a bushel ; opposite the
Hat Factory, first station on Columbia branch RR. If m.
S. W. of Sinking Springs. Slaty, curly, crushed beds next
the road, expensive and irregular to quarry. Elsewhere in
the vicinity beds dip regularly S.
Seltzer's quarry, m. W. of last, old ; beds fairly good,
weathered, broken, irregularly dipping 35, S.
Old quarry, long abandoned, 8 m. W. of Reading (near
Wernersville), beds very hard, with occasional slate part-
ing, irregular, dip ? 55, S. 20 E.
Miller's quarry, E. end of Wernersville, 300 yds. W. of
last, small exposure of thin beds, dipping 25, S. 20 W.
(not E.).
BrinMey and Zinris quarry, opposite Wernersville
station, once used by Reading and Pottstown furnaces, now
for farm lime ; 125'xlOO', face 25' high ; beds in west wall a
compressed anticlinal roll leaning over to the north, both
legs dipping 45, S. 20 W. (not E.) and only 10' of beds,
as thus doubled, visible.*
Whitmoyer BroS s quarry (KnoTr' s), near Wernersville
station ; large, 20' high ; 2 car loads a day to Reading and
Pottstown furnaces ; dip 20 to 40, S. 35 W.
Deppen's, J. W. (No. 1); an immense quarry N. W. of
Wernersville ; very old ; 3 kilns ; much flux also sent to
furnaces ; stone not quite good enough for flux ; 550 / x300 / ;
25' face of beds dipping 20, S. 20 W. ; bedding not es-
pecially prominent, and much of the stone quite silicious,
pale blue to grey. (No. 2) on a line with the last further
east and in the same beds, 9 kilns sometimes in use.
Hull' s quarries (two) west of last, small ; beds quite con-
glomeritic (not plainly stratified, dip (?) 20, S.) containing
a number of different silicious limestone and sandstone
* This is a notable instance of the complicated structure of the whole lime-
stone belt, and of great value to the geologist ; but it must be used with due
precaution ; for it may mislead the student into the error of doubting the
normal south dips when they present themselves, as in the exposures south
of Lebanon.
BERKS COUNTY QUARRIES. 313
pebbles, only sligJitly rounded, and all firmly cemented
together * A quarry, m. E. of last, in bluff 400' N. of
pike ; lean, cavernous, pale blue, abandoned.
GouTs quarries (three) in a N. W. S. E. line crossing
the RR. 3 m. W. of Wernersville (H m. E. of Robisonia);
(1) just S. of pike ; 2 kilns ; good, heavy bedded, dipping
55, S. 40 W. in N. wall, arched over to a less sleep S. 40
W. dip.-f(2) S. of RR. (11 m. W. of Reading); disused ;
moulh of cave; dip 30, S. 40 W.J (3) S. E. of last, small,
1 kiln.
Two small farm quarries, m. N. W. and in line with the
three Goul quarries show dips of 40, nearly due S. and
40, S. 15 W.
Wenrich's (W.) quarry on the hill slope S. of RR. 1 m.
S. E. of Robisonia station ; small ; dip 40, S. 15 W.
WenricKs (A.\ % m. N. of the station ; 35, S. 20 W.
Deppen's (Sam.} S. of RR. m. W. of Robisonia sta-
tion ; 2 kilns, 35,000 bushels per annum ; some building
stone sold, but beds thin and broken ; dip 20, S. 20 W.
A quarry, on the RR. H ni- west of Robisonia station ;
small ; important as showing a dip of 85, S. W. Another
\ m. W. of it, just N. E. of AVomelsdorf station, worked
for RR. ballast, dips 60, S.||
Moore 1 s quarry, on RR. 1 m. W. of last, and S. W. of
Womelsdorf ; small ; much earth to strip ; beds ' to !'
* These conglomerates are among the strangest phenomena of the forma-
tion No. II, and very hard to explain. Were it not for the sandstone peb-
bles, they might all be taken for breccias, or crushed limestone beds
cemented.
fHere then is another evident compressed, overthrown anticlinal, not
quite transverse to the strike of the belt, but very oblique to it.
I The stone here is reported quite manganesian. This shows that we are
in the lower division of the formation (Ha); and the sum total of dips
southward must be interpreted and calculated with this fact in view.
This only emphasizes the general rule of the whole limestone belt, that
the strike lines are all local, and cannot be followed for even half a mile.
In other words the irregularity of limestone strikes is as great and universal
as that of dips. The compression of the formation was equal in all direc-
tions vertical and horizontal. The structure could not exhibit these features
had the movement not been effected under the enormous weight of the
higher Palaeozoic formations.
|| These are instances of very high dips which help to give credence to the
overturned anticlinal exposures.
314 GEOLOGICAL SURVEY OF PENNSYLVANIA.
thick ; very dark blue, medium quality for flux ; good for
ordinary building ; dip, 35*, S. 10 W.
Lebanon county quarries.
Gehref s quarry, on RR. near county line, W. side of
steep hill, E. of Sheridan furnace, small, fair building stone.
EckerV s, small quarry N. . of RR. W. of Sheridan sta-
tion. Kauffman & CoS's, m S. of Sheridan station, once
worked for flux, lean and slaty and abandoned for the Ann-
ville stone now in use.
Kauffman & Co.'s large abandoned quarry, just S. W.
of Richland, slaty beds, dipping 25, S. 15 W. round to
due W.* Shaffer & YingsC s small pits, in hard, silicious,
irregularly disturbed beds. Landls 1 quarry, on RR. at
Richland ; old ; all stone (when quarried) sent to Tamaqua,
Schuylkill conuty, lime kilns ; quality fair ; beds of variable
thickness, broken, dipping 15 to 20, S. 25 W. Loose's
two small quarries, m. W. of last, 75' long, 20' high ; dip
15, S. W.
HartlieV s quarry, on RR. 2 m. W. of Richland, 1 m.
E. of Myerstown ; stone admirable for curbing, paving
and light building ; light covering; dip 10 to 15, S. 10
to 20 W.Jtoyer's, near last ; 300' long along RR., 20'
high, beds ' to 3' thick, uniformly good for building and
curbing ; dip 10, S.
Myerstown, three quarries on the canal, by which their
stone is shipped to Reading for plastering walls : Miller,
/!, in thinly laminated slaty beds dipping S. E. (not S. W.)
Miller, /., dip, 20, S. 10 E.Donaes\ 250' long, 22' high
in N. face, which shows a small anticlinal arch, dipping
20 to 35, east (not south, or S. E.)beds thinly laminated,
with some slaty impure layers ; 2 kilns of 300 bushels
capacity each.f
Sassier quarry, 1 m. W. of Myerstown, m. N. of RR. ;
35 years old ; 2 kilns of 350 and 400 bushels capacity ;
*Here is a specimen of the universal warped structure of the whole belt,
full as it is of innumerable small short dying anticlinals around the ends of
which the strike lines swing sharply, and throw the dips off fanwise.
f Here we have both anticlinal and transverse dips.
LEBANON QUARRIES. 315
45,000 bush, have been burned here in one year all for farm
use at 8 cents per bushel ; in 1886 only 4,500 ; 250' long N.
and S. by 150' E. and W. by 20' high ; dip in W. wall 32,
S. 22 E. in N. wall 45; in E. wall still steeper.
UricKs ( Vol.} quarry, m. W. of last, m. N. of RR.,
semicular, 70' long, 18' face ; 2 kilns ; 3,000 bush, per sea-
son for farm use ; beds good, hard ; J' to 2f thick, easily
quarried ; produces some of the best building stone in the
whole Lebanon Valley; much of it used for building; 2
horse load sold for 75 cents, (1 perch measured in the wall)
if the purchaser loads and hauls his own stone. Dip, 55,
S. 15 E.
Urictts (S.) \ m. W. of last, on canal, very long rambling
quarry. 200' wide near E. end ; one pit at the lock, 100'x-
50'xlo' deep ; dip here 60, S. 20 E.; in N". face 57, S. 25
E. ; in next pit 55, S. 15 E. ; stripping uniform and rather
heavy ; stone good flux shipped east.
Beckley 's, 1 m. S. W. of last, | m. S. E. of Prescott sta-
tion, small, 1 kiln of 250 bush, drawing 80 bush, per day ;
quarrying costs 5 c. per 100 bushels ; lime sold to farms at
8 c. per bush.; ballast delivered on RR. track for $1 per
one-horse load. N. B. this is the last quarry until the
Lebanon quarries are reached, four miles further west.
Lebanon city group.
At Lebanon, on the east side of the city is a line of
quarries extending N. and S. viz.: Horst's & Fritz's N. of
the RR., Shenk & Herr's, Wagner's, Houck's, ,
March's and Coleman heirs', S. of the RR. On the west
side of the city are: Brock Bro.'s, N. of the RR. and
Meily & Brother's, Groninger's, Coleman heirs' and Horst's.
Horst quarry, very old, 150'x250'x40' deep ; 2 kilns,
drawing each 125 bushels daily; yearly output 35,000
bushels, worth 12 to 15 c. picked lime delivered, 4 c. slaked,
used chiefly for mortar and plaster ; beds 1' to 2'; dip 35,
westward, in some parts swinging round to the south. In
a brick yard quarry, 1000' E. of last, the limestone beds
dip 35, S. 25 W. Fritz's quarry, abandoned; 2 kilns
(supplied from Wagner's quarry); bluegrey beds, withou
316 GEOLOGICAL SURVEY OF PENNSYLVANIA.
regular dip : cleavage planes 70, towards W. ; 275' long,
20' deep, stripping heavy.
STierik and Herr' s ; old ; 2 kilns ; 120'x75'x20' deep, dip
on W. side 15, westward ; on E. side 55, southward.*
Wagner' s; % m. S. of last ; 160'xlOO'x20'; beds massive,
used largely for Lebanon city buildings ; dip 35, S. 30 E.
HoucJc's, S. end of city ; 100'x20'; good bluegray beds,
dipping 35, S. 30 E. Another, near it, exclusively for
building stone, 250', E. and W. 20' high ; dip 20-30, S. E.
(This stone is finely laminated.} March's, near the last,
and on the Cornwall and Lebanon RR. 175' N. and S. 35'
deep ; flux and building stone ; dip 20, S. 50 E.f
Coleman heirs', two, immense quarries, old, abandoned,
together 1000' long, along the RR., formerly fluxing
Cornwall andDonaghmore furnaces, but too hard and lean ;
N. quarry beds all dip 35, S. ; S. quarry 32' wide, 35' deep,
dip 35 to 50, S.
Brock Brothers' quarry exclusively worked for the N.
Lebanon furnaces, on the old canal ; 400'x500'x40' deep ;
steam drills, etc., in use ; 35' of beds (!' to 4' thick) dip
20, S. 20 W.; in places wavy; but in S. and E. sides
strata even beds and regular dip ; the stone is light gray to
pronounced blue and of superior quality, but not quite so
non-siliceous as the Annville stone.
Meily & Brother, just S. of their Lebanon furnaces, S. of
RR. ; started 1868 ; in 1886 400'xlOO'x30' deep ; very
handsome face, especially along the north side of main cut.
and dipping gently 15, toward S. W.; stripping heavy;
massive stone can be quarried through the larger part of
the uncovered area ; stone blue-gray, somewhat lighter than
Annville stone ; beds thin and massive (!' to 3') quite free
from silicious matter / quarry contracts, 30 c. a ton ; 1200
tons of flux per month.
Gloninger estate, small, 1 m. W. of Lebanon center, on
Quittapahilla creek, 2 kilns, each draws 200 b. per day ;
12 c. picked, 6 c. per bushel run of the kiln ; local mar-
ket ; dip, 25 to 45, S.
* Another case of rapidly changing dip ; or warp.
f Here we have one of the very highly diagonal strike lines.
ANNVILLK QUARRIES. 317
Coleman heirs*, near Donaghmore furnace ; hillside
quarry ; dips S.
Coleman' s quarry, on RR. just W. of Colebrooke fur-
naces, 2m. W. of Lebanon city; enormous excavations;
output of flux for the Colebrooke furnaces very great ;
steam drills, etc.; all the strata good, lie very flat, but gen-
erally dip gently southward.*
The Annville group.
Annville is 4f miles W. of Lebanon city. Kr eider's
quarry is 3 miles W. of Lebanon, on the RR. If m. E. of
Annville ; started 1885 ; 100'x90'x20'; exclusively for flux,
15 small car loads per day ; strata vary ; 30' of good blue
stone; stripping heavy; dip of S. face 12, S. 10 W., of
W. face 15-20, S. 60 W. Yoke's, \\ m. E. of Annville,
small, 2 kilns. Kreider 's, m. E. of Annville ; good stone,
dips steep S.
Light and ffouser's quarry' just W. of Annville ; stone
deep blue, excellent ; stripping heavy ; long cut in hill-
side to reach best stone in S. end, where 75' wall, 20' high ;
cleavage prominent (with slips 75, N. 80 E.) dip 25, W.
and 25, S. 10 W.
Beaver's quarry, just W. of last, on same S. side of
creek ; old, large, 600'x800', back from creek to pike ; dip
everywhere gently S. E. and S. W.; small roll, one-half
of saddle exposed, with 35 dip, diminishing rapidly to 10
at the pike. Farm lime and chemical lime, and much fur-
nace flux (80 tons a day to Sheridan and Topton). In 1886,
1,000 bush, lime a month went to C. Warner & Co.'s paper
works at Wilmington, Del. Five draw kilns, 6'x26', 150
bu. per kiln, four always in action. Cost of quarrying,
breaking and delivering at kiln, 85 c. per 100 bushels, pow-
der and tools furnished to contractor. Fhix stone sold on
cars at quarry for 41 c. 'per ton. Analysis 96 to 98 per
*Here is a typical case of undistured localities in the great belt, which
have escaped the otherwise ubiquitous pressure-crumpling. The belt is here
nearly at its widest, and the quarry is not far from the edge of the slate belt
to the north of it Consequently the purer beds of the upper or Trenton
division (77c) of the great formation are here quarried.
318 GEOLOGICAL SURVEY OF PENNSYLVANIA.
cent. carb. lime. Light and Housed s, small, new in 1886.
Messner's, old, abandoned.
Kauffman & Co? s two quarries ; one on RR. 250' from
creek ; beds V to !', very regular and uniform, 25 to 30,
S. 10 W. The other S. of it, 150' wide, 20' deep ; stone
finely laminated, dips 20, S. 40 E. (sometimes swinging
to S. W.); beds not massive, nor thick, and more gray than
the other Annville stone ; output of both quarries 3000 to
4000 tons per month to Sheridan and Reading furnaces.
Brightbill & Sorts two very large quarries on RR. If m.
W. of Annville ; one 500' long ; 50' of rock exposed ; ex-
cellent, fine-grained, soft, brittle, blue-gray, thin beds,
wavy on W. side, regular (on E. side) dip 60-70, S. 40
E. Crush in S. face.
Kr eider's quarry just west of last ; 5 kilns, output 5500
bush, per month shipped to Powers & Weightman's
chemical works in Philadelphia, and to Pa. Salt Co. Always
in high repute for chemical and other special uses, and
flux ; 100 bush, lime from 6 tons stone and 17CO Ibs. coal
(best record); output of flux stone 1000 tons per month, at
31 c. per ton on car. Quarry 250'xl75'; 10' to 30' deep ; dip,
12 to 45, S. E.
Batdorff & Beaver's, next west in the line; 300' long,
irregular shape, 40' to 50' face in places ; inexhaustible
quantity of first-class limestone; output 2300 tons per
month ; best stone from center of quarry ; blue, soft, %50'
thickness of beds suitable for the market ; dipping uni-
formly, 40 to 70, both to S. E. and S. W.*
ShenJc BroSs old quarries, | m. W. of last, small, aban-
doned, 10' face, dip 65 (?) S.
Oruber & Bowman pits and kilns at Palmyra, near the
Dauphin county line, furnish good building stone, and farm
lime. Their beds have no geological connection with the
Annville beds (3 miles E. of them) and are out of line with
*There are slaty layers in this quarry which do not appear in Kreider's
quarry probably because they run past the Kreider quarry to the south of
it. It is a task for a future survey to clear up the geology of this important
line of beds ; to determine whether these dips are overthrown or not ; to fix
their place in the column of II a, 6, c ; and to reveal their connection with
the slate belt III a, &, to the north of them.
DAUPHIN COUNTY QUARRIES. 319
them far to the south, but in line with the first quarries in
Dauphin county next to be described.
Dauphin county quarries.
Shenk (Ab.) quarry, 1000' S. of RR. 1 m. W. of Palmyra
station, in horizontal strata* peculiarly adapted for build-
ings, in layers from 9" to 2', sold at the quarry for 60-65 c.
on cars at RR. station for 90-95 c. per perch. Barber's
(JR. RR.)%m. W. of last, on S. side of RR.; old ; dip 10, S.
Landis quarry, m. N. of RR., m. W. of Lebanon
county line and m. N. W. of Shenk quarry ; superior
quality of bedsf (Trenton?); 6 kilns, for farm use from
1856 to 1881, since then for building and plastering also ;
SCO' long N. and S. 50' wide, 30' face, dip 35 to 40 S. 20
E. Gingrich's quarry near and south of last ; face 25'; dip
25 to 35, S. 30 ~E. HoJce's, near last, abandoned, dip 60,
S. 25 E.
Mayer's abandoned quarry just S. of Derry station, on
steep bluff facing Spring creek ; beds ' to 3' thick, dip
50, S. 60 ^.Hershey quarry, near and E. of last ; build-
ing stone for new Derry church ; 50 / x25 / , 18' face, dip 12
to 20, S. E.
Swatara quarries.
Kavffman & Co., abandoned, 300' long, face 20', dip S.
E. Landis quarry, facing last on W. and Zimmerman
quarry its continuation north.:}: Landis kilns (3) put out
2800 bush, lime per week. Dip of S. end of Landis quarry
45, S. E. Zimmerman quarry makes a fine display of
* Perhaps with the slightest possible slope S. E.
t Rock grey- blue ; output 6000, 7000 bush, per month, all sold in Philadel-
phia and New York for paper, glassware, sugar refining, medicine, as well
as building, large wagons holding 85 to 90 bush. (80 Ib. to bush.) take it to
Palmyra station ; hauling $1.75 per 100 bushels; kilns, 6x18x20, consume \\
tons pea coal to 100 bush, lime ; drawn twice a day.
J There are only 26' of interval strata between the top Zimmerman bed
and the bottom Landis bed ; but the strata are crushed and folded, hard to
read, and expensive to work. The deep blue massive Landis N. beds can
be faintly identified with the S. Zimmerman beds.
See statistics of hands, powder, etc., etc., in An. Rt 1886, part IV, p. 1535,
by d'Invilliers.
320 GEOLOGICAL SURVEY OF PENNSYLVANIA.
good stone for lime ; 60' of beds exposed dipping 20 to 25,
S. E.* Output 13,000 bush, of farm lime per year.
Union Deposit Furnace Co.s" 1 large quarry just N. W.
of Swatara station, E. side of branch RR. to furnace ; 200'
(N. & S.) long, 35' working face, displaying WO' of suc-
cessive beds all dipping 60, S. 35 E.; lower beds.(N. end)
somewhat slaty ; center beds handsome blue stone (like the
Annville stone only rather more massy V to 3' thick); best
center beds measure 25'; upper (S.) beds broken by cleavage,
not so pure, harder to quarry.
Erb's quarry, \ m. N. of Swatara station, N. side of
Spring creek ; 125' (N. & S.) 22' high ; tightly folded beds,
dipping E. (?), 3 kilns for local market.
Ginrlch 's three quarries f m. N. W. of Swatara station,
S. of Swatara creek, close to the edge of the slate belt (Hudson
River Slate, No. 111.) (a) 180' long, 20' face, dip at E. end
45, S. 25 E.; at W. end the same -but more massive ; (b)
125' long, 28' face, beds wavy, dip irregular ; (c) 175' long,
20' face. Average stripping (on all) 5' ; beds 1' to 4' thick,
each layer very uniform, f
Hummelstown group.
Garman's, 1 m. E. of Hummelstown; long disused 100'
long, 20' face : beds hard and slaty, dipping 30, S. 60 E.
(i m. E. on RR. there is a dip of 45, E. S. E.)
Hershey 1 s three small quarries, m. E. of Hummelstown,
on branch RR. to Walton's Brownstone (Trias) quarries;-
(a) 75' long, 15' high against steep W. hillside, in beds slaty
and finely laminated, dipping 25, S. 40 E; (b) on level,
older, 40' diameter ; (c) at limekilns, small. Analysis
(claimed) 97 to 98 p. c. carb. lime. Building stone sent to
* Thickest beds 3 ; much good building stone could be obtained here, the
stratification is so regular ; breaking in rectangular blocks.
t The fifteen quarries just described (Palmyra, Berry, Swatara groups)
work a belt of upper (Trenton ?) limestones next to the slate belt, under
which they should descend. And yet all the dips are S. S. E. away from
the slate belt. This parallelism with the slate belt edge precludes the
notion of nonconformability ; therefore there must either be an upthrow
fault ; or all the limestone beds must be overthrown and therefore reversed,
the lower beds lying upon the upper.
DAUPHIN CO. QUARRIES. 321
Harrisburg builders, and Reading bridge work.* Dip in
all three S. & S. E.
Holler's^ at Hummelstown. between RR and Swatara
river ; 250'xl25'x25' face ; beds 4" to 3', dipping uniformly
23, S. 10 E.; stripping averages 3'; sold for building; 4
kilns, output 40,000 bush, per year. Rutherford's, \ m.
W. of last, on N. bank of river ; 200', narrow, 20' face,
building stone like last ; dip 20 to 30, S. 40 *&. Eagle's,
on turnpike at bridge, f m. W. of Hummelstown ; small,
for local farm lime ; dip obscure, gently S.
Beaver station group.
Allweiris quarry, 300 yds. E. of Beaver station (175 yds.
N. of RR.) on the edge of the slate belt; 200' long (on N.
side of steep bluff), 25' face ; dips observed 30, S. and 60,
S. 23 W. showing much warping, f
Webner's quarry, abandoned near RR. E. of Beaver
station; beds thin, S. dip. Rutherford's quarry just W. of
station ; 150'xlSO'; 30' N. wall ; dip in N. wall 30 S. becom-
ing quite flat southward along E. and TF. walls. 4 Some
beds large and massive building stone ; 2 kilns, 20,000 bush,
farm lime per year. CasseV s quarry, long abandoned, mid-
way between Beaver and Rutherford stations.
* None of the layers exceed 4', but there is little cleavage.
f A. very Interesting locality, being near the east point of a long narrow
belt of limestone enclosed between the great slate belt on the north and an
isolated branch of it running from it S. W. and W. to the Susquehanna below
Harrisburg. The limestone belt must be anticlinal ; and the slate branch
belt synclinal. On the RR. near Beaver, limestone dips 20, S. E. towards
the southern slate ; so also 20, S. dips are to be found along the south edge
of the limestone belt one and two miles from the river. On the RR. ap-
proaching the Susquehanna limestone N. dips are seen, as if going under the
great slate belt edge to the N. But generally almost universally the lime-
stones dip S. at various angles, as will be shown in the description of the
quarries between Beaver and Harrisburg. Of course the 30 and 60 S. dips
in the text above must be overturned N. dips. What makes this more
striking are slate dips of 35 and 32 S. within a mile E. N. E. of Beaver.
These and also, 58, 40, 60, 70 S. dips in the slate belt a mile and more
north of Beaver, must be all or most of them overturns.
t This would make an overturn of the 30 dip an impossibility ; and an
anticlinal between the quarry and the slate edge on the north a necessity,
unless an upthrow fault be made to run the 7 miles from Beaver to Harris-
burg.
21
322 GEOLOGICAL SURVEY OF PENNSYLVANIA.
Paxtang group.
Metes quarries E. of Paxtang station. (a) 150 yds. N. of
RR. 250' E. & W. 20' to 25' face ; hard, thick, building
stone beds, dip in S. face 55, S. 20 W.; in E. face 35, due
S.; 4 kilns. (b) 50 yds. N. of last, 100'xlOO'x25'; dip wavy,
25 to 35 S. W. (c) N. of RR. m. E. of station ; regular
beds, 1' to 2|' thick, dipping 25, S. 5 W. (d) S. of RR.
near last ; beds of pale blue, or bluish grey inclined to be
cavernous, 6" to 2' thick ; output 60,000 bush, in a single
year (3 kilns).* WilJielm? s quarry a little north of (c), beds
V to 3', dip 20, S. 15 E.
Rutherford? s (J. A.) \ m. S. E. of station, (3 m. E. of
Harrisburg) worked in 1884 for fluxing McCormick & Go's
Paxton furnaces ; large N. E. S. W. opening each side of
Spring creek ; beds very fine grained ; so much cleft as to
obscure the dip, which is S. S. E. in 40' of beds, S. end.
Rutherford estate quarry J m. S. of station S. side of
Spring creek ; 2 kilns, best lime hauled to Harrisburg where
it brings 16c. per bushel ; local farm lime, 7c. ; 2240 Ibs.
coal to 100 bush, lime ; 30' face of good grey-blue strata,
dipping 40, S. 15 E. (cleavage 55, N. 15 W.).
Rutherford No. 0, N. of RR. close to station ; 200', E.
and W. ; long abandoned ; beds hard, siliceous, like or per-
haps the same as the beds in the RR. cuts towards Harris-
burg. f
McCormick' s quarry, on RR. f m. W. of Paxtang station
and 2 m. E. of Harrisburg; 400' long (S. W.); best stone
now got at S. end ; good, pure, smooth-grained, gray lime-
stone, very low in silica, and easily quarried ; beds 2' to 4'
thick ; 40' face ; dip generally S. E. but a small synclinal
and anticlinal roll near center of quarry close to a clay
seam (fault f}^. Output of flux for Paxton furnaces at
Harrisburg 165 cars of 16 tons each per month ; quarry
* See statistics of work, cost, etc., in An. Rt. 1886, IV, p. 1527.
f No dip is given by D'Invilliers; but on Sander's dip map of Dauphin a
N. dip is here marked ; which, if true, is important.
f It seems as if the change from the northern 4 to 12 p. c. siliceous beds to
the southern non-siliceous beds took place at the clay seam ; the color cer-
tainly changes there, the siliceous beds being a medium blue.
DAUPHIN CO. QUARRIES. 323
started April, 1886; steam-drill (2" diam.) drills 80' per
day. An old quarry, 300' E. of last, shows a synclinal
with gentle dips on S. side and 70, S. 30 E. on N. side.*
Wister BroSs quarry, on RE. If m. E. of Harrisburg ;
stripping 8' over 30' beds (6" to 3"), of good quality, mostly
massive, full of cleavage planes ; dips at both ends 42-52,
S. 10 E.
Great quarries are seen in the hills facing the Susque-
hanna south of Harrisburg, furnishing flux to the iron
works.
* Precisely the reverse of what we should expect ; even an upthrow fault
north of it would not furnish a probable explanation, for such a fault would
have a N. dipping brush on its southern side. We must take this, like so
many other structural features of the limestone belt, as an exhibition of the
infinitely irregular effects of the general movement-pressure. The common
diagonalism of these dips to the straight course of these anticlinal limestone
belts is very remarkable and hard to explain.
324 GEOLOGICAL SURVEY OF PENNSYLVANIA.
CHAPTER XXVII.
Limestone quarries of the Or eat Valley west of the Sus-
quehanna, and in Mountain Creek valley.
Cumberland county quarries.
Opposite Harrisburg there is a continuous exposure of
upturned limestone beds in the Susquehanna right bank,
and in the railroad cuts, from Bridgeport down (south) to
New Cumberland, a distance of two miles ; this being the
width of the Beaver-Rutherford-Paxtang limestone belt (of
the quarries last described) where it crosses the river at and
below Harrisburg. The belt is enclosed between the great
slate belt on the north, and an outlying synclinal slate belt
on the south ; as shown on the colored geological map of
Cumberland county.*
All the exposures of limestone for the whole width of the
belt show south dips ; and yet the belt ought to be anticli-
nal, with south dips at New Cumberland and north dips at
Bridgeport. Consequently the south dips at Bridgeport
must be overturned north dips ; but the overturn is so ex-
treme that the beds dip only 30, with great regularity and
perfect conformability along the whole face of the great
quarries of McCormick & Co., beginning at the limekiln
south of the west end of the Harrisburg bridge. The low-
est beds at the limekiln must therefore be geologically the
top beds of so much of the series as is exposed in the quar-
ries ; and the slates at the bridge instead of overlying them
must descend southward beneath them.f
* Published in Atlas to D5, with Franklin and Adams county maps, etc.
t It is impossible to construct the curve of such a gigantic collapsed over-
turned anticlinal without imagining a slip fault on the north side of it,
either in the limestone or in the slate, or between the two. There is no
sharp distinction between the limestone and slate formations; the limestone
grows shaly upward and gradually merges into the shales; and this is well
shown by Mr. B. S. Lyman's field sections of the passage rocks between II
CUMBERLAND COUNTY QUARRIES. , 325
McCormick & Go's (old Walton) quarry, about m. S. of
the RR; bridge, exposes along the N. C. RR. about 400' of
strata dipping 25 to 30, S. ; varying in thickness from 2
inches to 12 feet solid ; and in quality from a nearly pure
limestone, with but 1 or 2 per cent of magnesia, to a nearly
typical dolemite with 35 or 40 per cent of magnesia.*
Williams' quarry, on Yellow Breeches creek, 10 m. S.
W. of Harrisburg, at the junction of the Dillsburg Branch
and H. & P. RRs. ; purer blue limestone 20', overlaid by
less pure greyish white 20', dipping 12 to 15, S. E. good
strong lime for local market.
Boiling Springs quarry, 5 m. higher up the creek, west;
60' face of blue limestone with smooth grain, in plates 6"
to 18" thick, dipping 20 to 30, due E. Furnishes flux to
Katharine furnace.
Woods', and other smaller quarries between Carlisle and
Mt. Holly, on the Gettysburg & Harrisburg RR. furnish
farm lime for local market.
Pine Grove quarry on Mountain creek, 7 m. above Mt.
Holly Springs, in the heart of the South Mountains, near
and 111 in the horse-shoe bends of the Conedogwinet creek north of Hoges-
town, Kingston and Middlesex a few miles further west. Therefore there
is no mode of exactly locating such a fault ; nor of determining its exact
shape, or vertical extent.
That the faulting was accompanied by much crumpling is plainly enough
visible to one standing on the bridge and looking down upon the river bed
(at low water) marked with beautiful zigzags of the slate edges ; proving
that the crumpling was not merely in vertical, but equally in horizontal and
in fact all directions.
The overturn is proved also by a 70 S. dip in the slates at the bridge ; by
the almost universal S. dip exposures throughout the slate belt; by the
great width of the slate belt (4 miles from Harrisburg bridge up to Marys-
ville RR. bridge in the gap) which can only be accounted for by many col-
lapsed and overturned folds in the slate belt itself; also, by the S. dips in
the outlying slate belt (\ mile wide) at New Cumberland ; and by the S.
dips of the limestone further south, where it emerges from the S. edge of the
same ; all concurring in one generalization, viz. , that the Great Valley rocks,
of all kinds, along the Susquehanna river, have been thrown into a series of
folds large and small, by a northward thrust of the region, whicfi, making
the folds, also tightly compressed them, and tilted them over to the north
of course giving a S. dip to them all.
* An elaborate if not exhaustive study of this admirable exposure was
published in report MM, 1879, pp. 311 to 362. The main facts and my deduc-
tions from them will be given in a subsequent chapter xxviii.
326 GEOLOGICAL SURVEY OF PENNSYLVANIA.
the Adams county line; opened more or less for a mile along
the outcrop ; but main output from one large quarry of flux
for Pine Grove furnace, say 2500 tons a year ; thickness of
beds, 100'; dip 25 to 30 S. E.; stone blue, massive, low in
silica'; pit 250'x75'x50' deep.*
Franklin county quarries.
Williamson' 1 s quarry (Hawbecker' s) on S. Penn. Br.
Cumb. Val. RR. 2 m. W. from main line above Marion ;
near the top of formation He (Trenton), the slates of III
outcropping to the W. and N. E. of the quarry ; large and
fine faces ; 75' to 100' of beds dipping 45, S. E. away from
the slate belt, and therefore overturned.
Mt. Alto quarry, f m. from furnace ; 60' face of beds
dipping S. E. ; good but rather magnesian flux stone; mixed
with Harshman quarry flux at Quincy, which shows carb.
lime, 95.482; carb. mag., 2.262; ox. iron and al., 0.440;
silica, 2.340.f
* Mr. King reports that these beds contain only 4 per cent carb. mag. and
5 of silica ; while the dolomitic limestone in the neighboring ore bank con-
tains 40 of carb. mag. and only 1 of silica. He says the "fat" valley stone
shows 12 of silica; and only 0.005 of sulphur, as against 0.125 sulp. in Pine
Grove stone. The car wheel iron of Pine Grove requires a minimum of
sulphur, and the chemical composition of the flux is therefore carefully
studied.
t All the limestone quarries described in the preceding pages, from
Reading to Mt. Alto, are more fully detailed in d'Invilliers' Report in An.
Rt 1886, part iv, pp. 1517 to 1562, in an order from S. W. to N. E. But little
or no account is taken of scores of farm quarries of very small size, mere
pits for obtaining a few loads of stone to build houses, or other farm use.
MAGNESIAN BEDS IN NO. II. 327
CHAPTER XXVIII.
Magnesian beds in No. II.
The most striking phenomenon of this great formation is
the subdivision of its vertical column into hundreds of beds
of limestone and of dolomite or magnesian limestone,
arranged alternately, regardless of their thicknesses, which
vary from less than an inch to several feet or even yards.
This phenomenon seems universal to the formation,
making its appearance in every natural rock exposure and
in all quarries ; compelling a systematic selection of certain
beds only for the service of iron smelters and lime burners,
and the rejection of the others in mining.
It was long ago well known that some of the beds of the
formation were highly magnesian, and that other beds were
comparatively pure limestones ; but no clear idea had been
obtained of (1) the relative number of the two kinds in any
given thousand feet of the series ; nor (2) of the relative
proportion of the total thickness of one kind to that of the
other ; nor (3) of the range of variation of magnesia in any
one bed, from top to bottom, or along the strike, or down
the dip ; nor (4) whether such variations in the charge of
magnesia bore any fixed relation to the variable sum of
other impurities in the limestone.
The geological and chemical literature of dolomites and
magnesian limestone rocks was very extensive ; but these
special features of their sedimentation had not been suffi-
ciently studied either in Europe or in America. The atten-
tion of geologists was fixed chiefly on a search for some
probable theory of the origin of dolomite beds as such ; and
the discussion of that special subject by European geolo-
gists was intensified by the Austrian survey of the Tyrolean
Dolomite Alps, about twenty years ago.*
* Richthofen in 1874 discussed the Coral reef origin of the Schlern Dolo-
328 GEOLOGICAL SURVEY OF PENNSYLVANIA.
The iron masters of Pennsylvania have always been par-
mites in the Tyrol. (Zeitschrift Deutscb. Geol. Gesell. Berlin, XXVI, ii.
225-256.)
Mojsisovics defended Richthofen's separated coral-reef theory ; referred
the conglomerated portions and oblique lamination to surf action, and the
thin beds to lagoon distribution. (Sitz. K. Ak. W. Wien, Math. N. H. Classe,
Abt. 1, Vol. 71, p. 719.)
Hoernes in 1875 published a preliminary notice of his views on the genesis
of the Tyrolean dolomite beds, in the Verhand. K. K. G. R. p. 290, and at p.
266, notices their change eastward. In 1876 he published another paper on
the formation of dolomite beds in the same, pp. 76 to 80. Afterwards a full
description of this chemical theory of Hoernes and Dcelter appeared in the
Jahrbuch K. K. G. R. XXV, iii, 293 to 332, giving the literature of the sub-
ject up to date ; a description of the Tyrolese beds and other Alpine expos-
ures ; analyses ; and their conclusion that the poor beds were of organic
origin, and that the rich beds were possibly organic limestones enriched
soon after deposit by the reaction of magnesium chloride ; the proportion of
lime being afterwards lowered by the sol vent action of carbonated waters.
Hoppe-Seyler, in 1875, showed experimentally that dolomite cannot be
artificially produced at ordinary temperatures ; maintaining that the mag-
nesia of dolomite beds could not have come from eruptive rocks, but must
have come from sea water heated by submarine volcanos sufficiently to ad-
mit of magnesian precipitations. (Zeitschrift D. G. S. Berlin, p. 495-930.)
Green (W. L.) in 1875 suggested the formation of extensive magnesian
limestone oceanic deposits out of the fine detritus of olivine volcanic sand
and dust, mixed with the extensively distributed fine detritus from coral-
reels. Such a mixture must cover an immense area of sea bottom around
the Hawaian islands and in other parts of the Pacific. (Jour. R. Geol. S.
Ireland [2] IV, iii, 140- 1*3.)
Murray (John) describes the universal distribution of volcanic debris
over the ocean floor, in the shape of deep sea mud, containing also peroxide
of manganese, native iron and cosmic dust, with local mixtures of wind
dust from desert regions ; and supposes the mixture of such deposits with
limestone precipitations to account for the red earth of Bermuda, Bahamas,
Jamaica, etc., but thinks that no analogous sediments can be found in the
strata of past geological ages. (Proc. R. S. Edinburgh, IX, pp. 247-261.)
E. T. Hardman discussed in 1877 his views of the history of Carboniferous
Irish dolomites, favoring their chemical precipitation. (Proc. R. Irish Acad.
[2] II, 7, pp. 705-730.)
Analyses of rock dolomite beds in the Carboniferous Limestone and Cal-
caire Grossier beds of Flanders, and in the magnesian limestone beds of
Durham (4 in number) by Corenwinder, will be found in the Ann. Soc.
Geol. du Nord (Lille) 1870-4, p. 17, 18, 19. Analyses of Silurian dolomitic
sandstones, by Stolba, are noticed in Jour. Chem. S. London, [2] XII, 967,
1874. Analysis by Roth, using dilute acetic acid on dolomite limestone, may
be found in Min. Mittheil. heft i, p. 69, 1876. Analyses of dolomitic con-
glomerate, with description of beds (Trias) are given by W. W. Stoddart,
in Proc. Bristol Nat. S. II, i, 39-47, 1876. Analyses of insoluble residues of
dolomitic limestones (Cretaceous, Jurassic, Triassic, Carboniferous and
Devonian), are given by Pfaff, in the Zeitschrift Ges. Nat. [3] III, p. 273-
294, 1878.
MAGNESIAN BEDS IN NO. II. 329
ticular in the choice of the beds they quarried for flux
stone, being guided for a long time by experience alone,
but in later years by the analyses of their own chemists. A
vast number of such analyses are on record in the office
books of iron works ; but while they show the range of
dolomite variability in the formation as a whole, they do
not show the variability of its beds in series of regular
superposition ; at least, not in a series of beds sufficiently
large to furnish a broad generalization. Serial researches
into the chemical character of the quarry beds on the Le-
high were not carried far enough, as may be seen by refer-
ence to Prof. Prime's Report D3, 1883, p. 187, where an-
alyses are published of 18 sub-divisions of 5 beds in Trox-
all's quarry, and of 14beds inEberhard's quarry, the latter
series being lower in the formation than the former, and
nothing coming of the investigation except the two facts :
(1) that there is very little variation within each series ; and
(2) that the upper series is almost exclusively limestone,
and the lower almost wholly magnesian.*
In like manner a series of analyses by Dr. Genth of 12
samples of the magnesian limestones (No. II) taken from
the banks of the Schuylkill between Conshohocken and
Potts Lauding, and from beds low in the formation, but not
consecutive, merely showed great variations in percentage
of magnesia, and especially of silica ; three of them, in
fact justify ing the term k ' Calciferous sandstone"; and three
others being extraordinarily pure limestones, f
*Thus : Sub-divisions of Troxall's quarry bed A, carb. lime, 77, 80, 82, 82,
80; B. 76, 86, 84, 72, 77, 74; C. 66, 54; D. 76, 61, 84, 50; E. 87. Carb. Mag. A.
1, 1, 2, 7, 4 ; B. 1, 0.4, 4, 3, 2, 3 ; C. 15, 14 ; D. 4, 2, 2, 1 ; E. 0.5. (There are
probably errors of transcription in the second and fourth layers of bed D.)
The Eberhard beds read : Carb. lime, 55, 54, 68, 61, 64 ; 60, 55, 61, 60, 57 ; 60,
59, 50, 57. Carb. mag. 35, 36, 21, 27, 23 ; 21, 27, 23, 33, 26 ; 31, 25, 22, 9. Silica,
2, 3, 3, 4, 4 ; 4, 12, 6, 7 ; 3, 6, 4, 16; Ferric Ox. and alumina, 7, 7, 7, 8, 9 ; 14, 6,
7, 2, 9 ; 6, 9, 14, 17. Phosphorus, .007, .019, .026, .017, .015 ; .007, .013, .005, .011,
.003 ; .002, .012, trace, .017. A residue of carbonaceous matter varying from
0.12 to 0.84 was left when any of the limestones were dissolved in acids, and
represented the organic life of that age. All the Harrisburg analyses showed
such carbon in percentages from 0.166 up to 0.560. Life must have been very
abundant.
t See report C6, 1881, page 126. Carb. lime, 60, 55, 42, 40, 48; 63, 92, 53, 58,
61 ; 93, 85. Insoluble residue, ?, 3, 26, 46, 38 ; 3, 8, 10, 6, 7 ; 6, 5. A complete
330 GEOLOGICAL SURVEY OF PENNSTLVANIA.
A large number of analyses of limestone specimens from
various other areas of No. II in the State, made by the
Chemist of the Survey, Mr. McCreath, and published in his
reports M, M2, M3, and in the reports of the various
counties where they were collected, do nothing more than
repeat and enlarge the testimony to the infinitely various
proportions of lime, magnesia, silica, alumina, etc. in the
beds of the formation, leaving the true mode of the varia-
tion from limestone to dolomite, to say nothing of its origin
and cause, quite unexplained. Up to 1877, no idea of how
the magnesian and non-magnesian layers are arranged had
been got ; no law of regular or irregular interstratification
had made itself apparent ; it was not possible to say
whether the several magnesian beds resembled each other,
whether the several purer limestone beds were alike or not,
nor in what degree, if at all, the two series represented two
kinds of physical action intermittent in the ancient seas.
Yet until this was learned we could not make the first step
towards a stable rational theory of our larger limestone for-
mations.
I therefore directed to be made in 1877 a careful sampling
of 115 beds (with a total thickness of 370 feet) exposed at
the old Walton (McCormick) quarry opposite Harrisburg by
the Northern Central railway cutting for a length of 800
feet : a consecutive series of beds, all conformable, and
dipping regularly southward at an angle of 30*
This afforded a good opportunity for collecting two sets
of samples, two samples from each bed, one at the soil above,
the other at the level of the railroad, therefore from 15 to
80 feet apart according to the varying depth of the cut; and
analysis of the fifth bed gave : carb. lime, 40.27 ; carb. mag. 31.24; insoluble
residue 28.49 (of which 24.23 was silicic acid or quartz). The specimens
analysed, No. 7106, etc. are labeled and preserved in the Museum of the
survey.
*The cut was surveyed and the beds marked by Mr. Sanders, who
numbered them from 1 to 98 (see Table X, M2, p. 353). Mr. Hartshorne saw
reasons for subdividing some of the beds and renumbered them from 1 to
115 (see Table XI, on p. 354). Mr. Sanders' sum total footed up 372' 9".
Mr. Hartshorne's remeasurement footed up 370' 10".
MAGNESIAN BEDS IN NO. II.
331
reduced from paqe-plcties in Rcpf-. MM,1S73, pp.355-35tf.
332 GEOLOGICAL SURVEY OF PENNSYLVANIA.
sometimes a third or intermediate sample. Many of the
analyses of individual samples were duplicated.*
A cross section of the exposure was published in M2, p.
344, and repeated (cut up into eight lengths) in four page
plates, pp. 355 to 235 ; all the beds numbered from 1 to 115
along the bottom line ; thickness in feet and inches of each
bed given on its face edge ; percentage of carb. magnesia
given below and above; the lime beds left white; the magne-
sian beds shaded, the darker or lighter shading showing the
proportionately more or less magnesian character of the bed.
This cross section reduced one half linear as exhibited on
plate 7, page 331, will give the reader a general idea of the
scope of the investigation and the facts it brought to light.
For a better study of it the chemist or geologist is expected
to resort to my original memoir in Mr. McCreath's Report
M2, the results of which I shall here state as succinctly as
may be.f
Table I (M2, pp. 345, 346, 347) shows in vertical columns
the carb. lime, carb. mag. and insol. matter percentages of
each bed, at grade and at top of cut4
* The investigation was put under the direction of the Chemist of the
Survey, Mr. A. S. McCreath. The analyses were made in the Laboratory
of the Survey at Harrisburg by Mr. Joseph Hartshorne in 1877-8; and con-
cluded by Mr. S. S. Hartranft'in the summer of 1878. The analyses were
published in full in Mr. McCreath's Report M2, 1879, pp. 312 to 341 ; with
three very interesting analyses of calcite contained in beds 9 and 23 (showing
about 88 p. c. of carb. lime; 10 of insoluble matter; 1 to 2 of carb. mag.;
about 0.2 of carb. iron ; about .03 of sulphur, and about .3 of phosphorus. ) ;
also two analyses of the flint in bed 5 (showing 90 p. c. silica ; 6 to 9, carb.
lime; 0.5 carb. mag.; 0.6 carb. iron ; .02 to. 06 alumina; 0.05 sulphur; and
traces of phosphorus. See M2, p. 342).
| A preliminary account of them will be found in a paper read before the
Amer. Philos. Soc., Phila., Dec. 20, 1877, and published in the society's pro-
ceedings of that date.
f Abnormal analyses are brought out by bracketing unexpected and per-
haps erroneous percentages, thus:
Bed 17, . .
26, . .
43, . .
62, . .
68, . .
77, . .
80, . .
81,
IAn
Grade.
. . 96.60
. . 90.00
. . 97.80
. . [49.80
. . 85.10
. . 85.50
. . 79.80
54.90
ie Carb.
Top.
[60.20]
[70.!<5]
[91.00]
61.90
96.00
97.90 '
95.90
56.70 ,
Magn
Grade.
1.10
6.80
1.30
31.90
"10.40
' 9.80 :
= 9.90 :
35.70
es. Carb.
Top,
[33.40]
6.30
[ 1.30]
28.40
2.30
1.80
2.00
24.00
Insol. Matter.
Grade. Top.
1.10 [ 5.90
3.40 [22.95
1.30 [ 7.90
[16.90] 8.20
3.20 1.90
4.50 1.00
9.40 2.60
7.70 18.40
84, .
66.80
[75.601
"27.20'
16.30
4.40 5.60
N. B. All percentages given in these tables are only to one or at most two
figures of decimal.
MAGNESIAN BEDS IN NO. II. 333
The first thing noticeable is that not a single one of the
115 beds is entirely destitute of the magnesia carbonate ;
and that in no bed does the magnesia carbonate rise high
enough to make the rock a perfect dolomite.*
The second remarkable fact is that the alternation of
magnesian and non-magnesian (i. e. of high and low mag-
nesian limestone) beds is constant, rapid and sharp ; for in
only one case, that of the group of beds 6, 7, 8, 9, 10, 11, is
there any appearance of a gradual increase and decrease of
magnesia in a sedimentary sense, f Seldom a bed occurs
with any intermediate percentage between the very high
and very Iow4
The third fact is equally striking and important, viz., that
so far as analyses at the two ends of the exposure of a bed
can warrant the assertion, each bed is wonderfully homo-
geneous in its magnesian character, whether .high or low.
In only a few cases is there any practical difference in the
percentage of magnesia at grade and at top. In those that
do occur, however, the difference is as great as that which
marks the alternate beds.
A fourth important fact is, that the greater percentages
of insoluble matter (silicates) are almost invariable found
in the high magnesian beds, the beds which are free of
magnesia being free of silica and alumina likewise.
*Bed 85 has only 0.9 at grade (4.1 at top); and bed 2 has 3&50 at grade
(39.75 at top).
f In these the mag. carb. p. c. runs thus: 1.40, 3.60, 14.50, 24.80, 8.05, 1.80 at
grade (and 1.30, 3.70, 7.50, 27.00, 8.15, 1.30 at top). This is also a fair example
of the remarkable uniformity of the two percentages at grade and at top in
each bed; proving (1) the general chemical accuracy of the laboratory
work, and (2) the general homogeniety of each bed from end to end of its
exposure.
t Such however are beds 14, 33, 36, 38, 55, 64, 84, 97, 104. Of the 32 beds
from 84 to 115, half of them are low (12 under 2.00, 3 under 3.00, the remain-
ing one 4.6); and of the other half all but two are high (9 range between
36.00 and 30.00, five between 30.00 and 25.00 ; one is 17.00, the other 14.00).
On page 348, M2, these are so arranged in a table that the rapid alternate up
and down oscillations are patent to the eye. It is specially remarkable how
few beds occupy an intermediate chemical position between the extremes.
In how many of these instances the difference may be due to some
accident in misplacing the samples, I cannot tell ; but they are so few that
they offer no great obstacle to a conviction that each bed is really a homo-
geneous deposit
334 GEOLOGICAL SURVEY OF PENNSYLVANIA.
Other facts are, that the planes of separation between
bed and bed are ordinary bed planes as in sandstone and
shale strata ; that no current, cross, or false-bedding is
visible ; that some of the beds (of both species, magnesian
and non-magnesian) are only a few inches thick, while
others are 6', 8', 10', 12', even 14' (bed 68) thick ; that there
is no rule by which to connect the thin beds with one species,
nor the thick beds with the other ; that a limestone layer
only 5 or 6 inches thick crosses the whole exposure between
two equally thin layers of dolomite, with no show of grading
into each other (the same analysis being got at both ends;
that two thick limestone strata will enclose a thin magnesian
layer ; and vice versa two massive dolomite beds will enclose
a thin limestone layer ; and finally, that beds of the highest
and lowest magnesian character lie directly and repeatedly
in contact with each other.
Negative deductions from the facts.
The only generalization I can make from the above data
is a negative one. namely : that no theory of percolation
can account for the facts ; that no theory of more rapid dis-
solution of carbonate of lime, leaving a growing charge of
carbonate of magnesia behind, will apply to rocks which
are neither honeycomb, nor visibly porous, nor unusually
cleft, nor otherwise disturbed; and that any theory to account
for the presence of the magnesia must treat the layers of
both species as equally mechanical sediments ; especially,
seeing that the larger part of the insoluble matter resides
in those which contain most magnesia ; while magnesia is
present in all of both kinds.
Amount of Magnesia present.
There only remains to be considered the question: whether
there be any feasable mode of calculating the actual quantity
of carbonate of magnesia in the formation, or in this
exposed subdivision of it, in proportion to the actual
quantity of carbonate of lime and insoluble matter which
together make up the bulk of the deposits. In other words :
what are the average proportions of the three principle
MAGNESIAN BEDS IN NO. II. 335
elements of strata 370 feet thick, by which we can judge of
their distribution through the whole formation several
thousand feet thick.
In attempting this problem the beds were at first grouped
in fives and averages taken (Table II, p. 349, M2); then in
tens (Table III, p. 350); lastly in three groups of 50, 50 and
15 (Table IV), which yields a final average for the whole 115
beds as follows : C. L. 80.662 ; C. M. 14.215 ; I. M. 4.715.*
Excluding the third element (insoluble matter) and calling
the carbonates of lime and magnesia 100, their average pro-
portion to each other in the whole 115 beds, taken together
as a solid series, stands 85.02 : 14.98.
The next step in the calculation was to separate the beds
into two series : the limestones (L.) and the magnesian lime-
stones (M.), and treat each series separately to get a grand
average for the whole. For this purpose I selected the 29
beds at the north end of the section (next the limekiln), 15
of them high in magnesia and 14 low, alternating with re-
markable regularity, f
Combining the top and bottom analyses of these 29 beds,
we get the following general average analysis of the high
magnesian beds (M) and the low magnesian beds (L): .
Table VII J M' ' C ' L - 63 ' 41 5 C - M - 28 ' 22 J Insol. 7.24
' t (L), . C. L. 95.77 ; C. M. 2.06 ; Insol. 1.42 J
which is probably as good a formula for the chemical dis-
tribution of the lime and magnesia constituents of our
Cambro-Silurian (or Ordovician) limestones as we are likely
to get by any such method.
* The reasons for the failure of worthy results from the smaller groupings
are given in M2, p. 350.
f Of the 164 percentages five were abnormal. These were included in
Tables V, VI b - , excluded from Table VII, p. 351, the general result being
however but slightly affected.
JThe direct proportion of C. L. to C. M. however is in (M) 69.2 : 30.8, and
in (L) 97.9: 2.1 (Table VIII).
To try the method in another form I selected 57 high and 58 low mag-
nesian beds (using only the figures of the fourth column of Table I) to be
treated in two separate series, sub-divided into four groups of beds (1) beds
1 to 30 ; (2) 31 to 60 ; (3) 61 to 90 ; (4) 91 to 115. The result was as follows :
Table TX $ < M ) C. M. (1) 27.96 (2)23.56 (3)26.05 (4)27.04
' \ (L) C. M. (1) 3.01 (2) 2.62 (3) 2.25 (4) 2.00
giving a general average of carbonate of magnesia in the 57 high magnesian
336 GEOLOGICAL SURVEY OF PENNSYLVANIA.
The different thicknesses of the beds must now be taken
into consideration ; for no possible combination of two
analyses from each bed of a series could possibly give the
true proportion of Jime and magnesia in the whole series
unless the beds of the series were all of equal thickness *
Treating the beds according to their thicknesses by the
formula given in the foot note, but using only the percentages
of C. L. arid C. M. in columns 1 and 3 of Table I (that is
the samples at grade line) I got the results of Table XII,
(M2, p. 359):
132.6' (beds 1 to 50) C. L. 92.00 C. M. 12.20
179.9' ( " 51 to 100) " 79.25 " 14.00
59.5' ( " 101 to 115) " 83.75 " 11.86
371.0' ( " 1 to 115) " 84.47 " 13.02
Considering the probable animal origin of the flints from
sponges, and the proven animal origin of the oolite beds
from broken up bryozoa, together with the known abund-
ance of molluscs, articulates, etc. in the waters of that age,
it is reasonable to ascribe part of the surplus of lime over
magnesia to that cause ; the small amounts of sulphur to
plant life ; and the small amounts of phosphorus to animals
like Lingula which preferred phosphate of lime to carbon-
ate v of lime for making their shells ; or perhaps to large
armored fish which a recent discovery informs us lived in
great numbers at the beginning (or before the beginning) of
the Trenton age ; though why no traces of such fish have
been reported from any Lower Silurian outcrop in the
world except only at one spot on the Colorado river is
wonderful enough.
beds, 25.89 ; and in the 58 low magnesian beds, 2.53. It will be noticed that
this result differs somewhat from that in Table VII in the text above, where
the figures read 28.22 and 2.06 ; but not more than we might expect from
using 115 beds in one case and only 29 beds in the other.
* Suppose for the sake of illustration we have a series of 100 beds, half of
them averaging C. M. 2.00, the other half averaging C. M. 30.00 ; if they were
all of equal thickness the general average would be, of course, C. M. 16.00.
But suppose the first fifty had an average thickness of only 1', and the
other fifty an average of 6g' (making a total of 375'), the calculation must
run thus: 50Xl'X2.00 -f 50 X 6. 5' X 30. 00=9850 percent.; which divided by 375'
gives & general average of C. M. 26.70. If the 1' beds were 30.00 p. c. and
the 65' beds were 2.00 p. c. the general average would be only C. M. 5.73.
Of course all this is only true on the presumption that each bed is in itself
homogeneous and would give the same percentage wherever sampled ; which
is evidently not quite the case.
HYDRAULIC CEMENT QUARRIES OF NO. II. 337
CHAPTER XXIX.
Hydraulic Cement Quarries of No. lie (Trenton] on the
LehigJi Gypsum.
These were referred to shortly in Chapter XXV, but
their importance demands a more detailed description.
Four companies have quarried and burned the stone, two
on the west and two on the east bank of the Lehigh at
Coplay, where the Trenton limestone with its cement beds,
crosses the river. These works are described in Prof.
Prime's Report, D2, 1878, pages 59 to 67.
The LeJiigh Hydraulic Cement Company commenced
operations in 1872, on the west bank, 1 m. above Coplay
station, Lehigh Valley RR. In 1874 the mill was burned
down. It had 3 run of stone, and could grind 300 bbls. a
day ; four kilns of No. 12 pattern as decribed in Gen. Gil-
more' s book on cement ; quarry near mill ; color of cement
light yellow ; very like in color and quality the old Lehigh
and the Allen cements.
The Coplay Cement Company, organized in 1867, have 11
kilns a short distance above Coplay station, 6 miles above
Allentown ; the quarry adjacent ; a steam engine hoisting
the quarry stone to the kilns for burning Anchor cement,
and at the same time running the crushers for Portland
cement; 7 set-kilns burn Saylor's Portland cement (Hu-
bett's London pattern) built of cement, concrete, firebrick
and iron ; total capacity 2,500 bbls. of Portland cement
clinker per month. The other 4 are draw-kilns, of Rosen-
dale, N. Y. pattern (Gilmore's No. 12), burning Anchor
cement, 300 bbls. per day. Store room capacity 15,000 bbls.
Some beds of the quarry are fit for Portland, others for
Anchor cement ; but good technical knowledge is needful
to decide what stone to use and what to reject, that the pro-
duct may successfully stand the engineer's tests. Of the
22"
338
GEOLOGICAL SURVEY OF PENNSYLVANIA.
samples of Portland cement made from 8 beds (of which
analyses are given below) some were very good, while others
fell far below the required strength.*
The requirements of the Department of Docks, New
York, in purchasing are as follows : Weight, per barrel,
400 Ibs. ; weight, per bushel, 110 IDS.; fineness, 80 per cent.;
tensile strength, at seven days, 250 Ibs. per square inch.f
Tests of Saylor's Portland cement as packed and offered
for sale in market, 4 in number, are tabled D2, p. 61 :
Weight per cubic foot, 112 Ibs. ; fineness through a 2500
mesh sieve, 85 to 100 p. c. ; date of grinding Jan. 12 ; dates
when blocks were made, April 26 to 30 ; weight of block, 24
and 25 oz. ; weigh t^ of water in each block, 5J to 6 oz. ;
temperature of cement and water. 60 Fahr. ; time to set in
mould, 16 to 20 minutes ; time left in mould, 90 minutes ;
immersed immediately ; left in water 6 to 7 days ; broken
immediately on being taken out of water ; age when broken
. 6 to 10 days ; average tensile strain on square inch, 411, 392,
426, 566 Ibs. ; 3 blocks made of each ; tensile strain per
* Analyses of quarry rock for Portland cement by Mr. John Eckert, under
Prof. W. B. Chandler.
Silica
12 88
12 81
13 72
14 68
15 03
15 40
1 79
14 32
Alumina
Ferric oxide,
Carbonate of lime
Sulphate of lime,
Carbonate of magnesia
Phosphoric acid
Organic matter, .... ...
4.25
1.09
72.87
1.60
4.69
.10
1.57
4.86
.97
72.64
1.68
4.62
.11
1.72
4.09
1.04
71.54
1.79
4.37
.10
1.78
5.32
1.12
69.26
2.29
3. 67
.09
1.68
3.97
1.93
74.12
2.41
.13
1.47
4.26
74! 66
.86
2.66
.09
.50
.34
7 .95
.75
.84
.06
1.46
4.20
1.65
73.12
2.02
4.09
.17
1.31
Total
99.05
99.41
98.43
98.11
100.25
101.19
100.69
100.88
Analyses of Portland cement made from the above beds.
Silica
Alumina
Sesquioxtde of iron,
Sulphate of lime
Lime
Magnesia
Total, .
10.11
1.61
1.78
23.40
8.06
2.38
2.44
59. 94
3.21
"ggls"
23.21
8.35
2.74
2.36
23.07
7.32
2.49
2.17
97.36
f A copy of official report on 1,000 bbls of Saylor's Portland cement, tested
Nov. 13 to Dec. 20, 1877, is printed in D2, p. 62. Average gross weight per
barrel, 400 Ibs.; average weight of U. S. bushel, 131 Ibs.; number of barrels
sampled, 105; average fineness, 82 p. c.; average tensile strain per sq. in.,
347 Ibs.; number of minutes in mould, 53 minutes.
HYDRAULIC CEMENT QUARRIES OF NO. II. 339
section of each block, (1) 875, 976, 925 ; (2) 825, 825, 1000 ;
(3) 950, 1025, 925 ; (4) 1325, 1350, 1150 Ibs.*
Saylor's Cement is fully equal to the English and French
Portland cement and is manufactured by the same patent
Aspdin process (L825), except that the quarry rocks at Cop-
lay yield all the needful elements, and therefore, does not
require the addition of clay, etc.f
Anchor Cement is a patented light burnt cement of a
peculiar chemical composition : sets rapidly ; has great co-
hesion ; becomes uncommonly hard both under water and
in air ; has a beautiful greenish gray color ; makes smooth
and uniform drain pipes, turned out rapidly from the mould;
is desirable for beton or concrete for bridge piers and abut-
ments. :{:
The Old LehigJi Cement Works near Siegfried's bridge,
E. bank of Lehigh river, erected by the Lehigh Naviga-
*Prof. Prime writes (D2, p. 62) Portland cement in England is made by
burning mixture of chalk and Thames river clay to a partial vilification.
A.11 attempts to find (or to properly mix) the proper rocks failed to produce
a cement equal to the best English and French brands, which is a triple
silicate of alumina and lime and iron, without any free lime, 'as a sharp
crystalline powder, varying from dark to light gray, with a bluish or
greenish tint. The Coplay Cement Company after long and costly experi-
ments in selecting and mixing several beds in their quarry got an analj'sis
thus : (1) Soluble in hydrochloric acid : Garb, lime, 70.34; carb. mag., 4.47;
carb. iron, 2.98 ; (2) Insoluble silica J4.73 ; alumina, 4.54 ; ferric oxide, 0.93;
magnesia, 0.89; water, 0.98=total 99.86. This mixture, when its carbonic
acid was driven off in the kiln, analyzed : Silica, 22.77 ; alumina, 7.03 ; lime,
60.91 ; magnesia, 4.67 ; ferric oxide, 4.63=100. Prof. W. T. Roepper of Beth-
lehem. But as the same quarry bed varies in quality, samples of stone are
frequently analyzed and burned in a testing kiln. The stone is crushed
and ground, thoroughly mixed dry and tempered with water in a pug mill,
spread out on drying floors, cut into bricks, placed in a kiln with alternate
layers of coke and burnt ; the clinker is then selected, the pulverulent
scarified, and the underburnt taken out ; the burnt bricks then ground and
stored in bins for a few weeks to sweat and cool before shipment to Com-
munipaw to be barreled and stored.
fThe N. Y. Dock Department used 5000 bbls. of it in 1877. The U. S
fortifications have made much use of it ; Gen. Gilmore fully endorsing it.
The East River Bridge Co. used it, Engineer Martin endorsing it ; and it
received a medal at the Centennial Exhibition.
fit was selected before all other American cements for the Giraid bridge
at Philadelphia. See reports of tests in Journal Frank. Inst. Phila. March
1874, p. 181 (copied verbatim into Report D2, p. 65, 66). The mixture finally
fixed on was: Anchor cement 1 part, sharp river sand 1 part ; furnaceslag,
4 parts.
340 GEOLOGICAL SURVEY OF PENNSYLVANIA.
tion Co. In 1872 leased by Gen. J. Selfridge and enlarged
to 200 bbls. a day ; new quarry opened on Hokendaqua
creek, 1 m. E. of old quarry a-nd on the same rock beds of
argillaceous limestone. Idle after 1875.
The Allen Cement Company, organized (1872), works at
their quarry on Hokendaqua creek, 1 m. E. of Siegfried's
bridge, Northampton county; 2 small draw-kilns and 2 run of
stone ; steam power ; 75 bbls. per day of " Allen " or " Key-
stone" light yellow cement. Idle after 1875.*
In Miffljin county.
A new dydraulic cement plant is about being established
at Milroy in Kishecoquillis Valley, on an outcrop of Tren-
ton limestone (1891).
In Centre county.
Hick 1 s Cement Quarry is on Logan's branch, south of
Bellefonte, in Spring township, close to the Benner town-
ship line. It is a small quarry of magnesian limestone (dip-
ping 15, S. 38 E.) near the junction of lib (Chazy) and lie
(Trenton) and therefore at the same geological horizon as the
cement quarries on the Lehigh near Coplay. Excellent lime-
stone beds, 150' thick in all, show below the cement works,
dipping 40-50, S. E. The plant consists of two double
kilns, each holding about 200 bushels, capacity 1600 bush,
per annum. It is near the site of the old Valentine furnace.
(Report T4, 1884, pp. 314, 341.)
*Prof. Prime in his report D3, 1883, p. 164, reported that both these works
had been idle up to that date, and added : " It must not be supposed that
because these operations have been apparently unsuccessful, that there is
no future in the business of manufacturing hydraulic cement in this part
of the State, on the contrary the success of the Coplay Cement Co. shows
what perseverance under difficulties can and does accomplish. Of course,
the composition of some of these cement-stone beds is far more favorable
to the manufacture of cement than that of others, but all may be more or
less profitably utilized by careful intermixture. There is no reason why
the manufacture of hydraulic and Portland cement should not be slowly
and surely extended, not only by rendering this portion of the State free
from foreign competitors, but actually rivalling these in many of the West-
ern markets on account of the excellence of the product and the cheapness
of freights."
LIMONTTE MINES NEAR THE TOP OF II. 341
CHAPTER XXX.
Limonite mines near the top of II. Ir onion in LeUigli ;
Moselem in Berks ; Cornwall in Lebanon ; Mt. Pleasant
in Franklin / Henrietta in Blair.
Along the northern edge of the limestone belt of the Great
Valley in Lehigh county, that is, not far from the foot of
the low hills which mark the southern limit of the slate
belt, and therefore along the outcrops of the top beds of
the magnesian limestone formation, lie a range of limonite
mines of considerable age and size, one of which is the
famous old Balliet mine, now known as the fronton mine.
It is difficult to make a clear statement of the geological
situation of the damourite slates which have furnished the
material for these pots of white and black clays, brown
hematite iron ore, and oxide of manganese ; but they seem
to be transition beds between the magnesian limestones of
II and the purely argillaceous slates of III ; and it may be
said without much fear of error that they are the repre-
sentatives of the Trenton formation, or of the lower part
of it, because Trenton fossils mark the range of argillaceous
non magnesian limestone beds which is traceable from the
cement quarries at Coplay on the Lehigh to and behind the
Ironton mine, that is between the ore pit and the slate hills.
How the Utica black slate formation (Z77a)is connected
geologically with the black clays of the mines it is not easy
to say ; for this formation has no. conspicuous outcrops
along the Great Valley, but only manifests its presence here
and there at long intervals between the Delaware and Po-
tomac, and seems to be merely a part of those passage beds
from the magnesian limestones of II up to the clay slates
and roofing slates of III which are so admirably and re-
peatedly exposed, standing vertical, in the bluffs of the ox-
bow bends of the Conodogwinnet in Cumberland county.
342 GEOLOGICAL SURVEY OF PENNSYLVANIA.
Some of these mines are close up to the edge of the slate
(III) ; others are at a distance from it of several thousand
feet, and ought to be at considerable depths below the slate
in the geological column.
Beginning with the first mines west of the Lehigh, on the
line of the Ironton railroad, we have, near Egypt, and 2 m.
W. of Coplay :
P. Steeple's three abandoned excavations , 1600' long. The
west end of the west one is m. from the edge of the slate
belt ; and yet on its south side is a large bank of the Hud-
son river slate (III6.) with a small quantity of Utica
black slate (Ilia.) on the dump. In the middle pit a little
black and red clay on N". side, and slate in several places.
It looks as if it were a deposit of surface ore in gravel over-
lying slates of Ilia and possibly III5. Blue and black
clay (Ilia decomposed? ) was struck half way down shafts
sunk in middle pit, and little or no ore found (D2, 46.)*
D. StecMe 1 s two abandoned pits in a parallel line with
the last, 1000' distant to south ; gravel ore.
J. Ritter's mine, west of the last, and only 800' from the
edge of the slate belt (as drawn on the large map of Report
D2), is 800' long by 500' wide ; abundance of black clay at
its south end in both E. and W. walls, and just below the sod ;
just under the black (and also east of it) an abundance of
white and pinkish c\ay ; line of color sharply defined ; com-
position the same,f dip different (black N. W. white S. W.)
but this may be due to folding and settling when the sup-
*It must be kept always in mind that the slate belt once extended over
the limestone belt These gravel banks are on two sides of a shallow vale
descending eastward, and they are the remnants of a much more extensive
drift deposit, the main body of which has been swept away in the erosion
of the vale.
f Analysis of "white clay" (1), and "yellow clay "' (2) by I. R. Shimer of
Lafayette College, and of "yellow clay" (3) by A. S. McCreath are given in
Report D, 1874, pp. 13 to 33. The yellow clay is used as ochre for paint. In
the range of limonite mines along the base of the South Mountain between
Easton and Bethlehem the miners call the White clay "hill clay " and
ceased to look for ore when they struck it, and are careful not to go through
it for fear of being drowned out. It is a working hypothesis that as the
damourite slates were turned into clay they were able to play the part
of an impervious water-bearing stratum, upon which iron solutions re-
mained tanked and threw down their limonite. (Prime, in D. p. 14.)
IRONTON LIMONITE MINES. 343
porting floor of limestone was dissolved away. IS". B.
Here there is a layer of limonite 8" to 13" thick which cut
through both black and white clay.*
The Ir onion mine, 2000' long by 800' broad and 90' deep
(in 1878) is owned, at the east end by the Balliet heirs, in
the middle by the Balliet brothers, and at the west end by
the Ironton company / worked since 1837, when the ore
showed itself above the surface of the soil ; limestone beds
at various points deepening from east end to west end ;
walls mostly plastic (damourite) clays, mostly iron-yel-
lowed, much white, some manganese, pink or red, also
masses of (Utica) black at N. W. end, in center, and at
east end.
The black clay masses, once continuous and now sepa-
rated by mining the ore, contains itself a curious ball ore
(siderite, carbonate of iron) like that so common in the
coal measures, but too little of it and too scattered to be
worth mining. Native copper also occurs in the black
clay, in small filiform pieces, having been reduced to na-
ture by carbon in the clay. The black clay deposit varies
from V to 10', and sometimes swells to 20'. It contains
graphite, which makes its genesis from the Utica slate still
more probable. f
Ore occurs in various parts of the mine, mostly under the
black clay, especially at the west end, in the central deep
pit, and along the northern side.J
*This remarkable fact is of great importance, but only increases the ob-
scurity under which the origin of our limonite deposits lie. If the original
undeconi posed black and white slates were of the same age and conforma-
ble, the ore must be of that age ; if the clays are of different ages the segrega-
tion of the ore layer must have occurred later. The ore of this curious layer
yielded to McCreath : Iron, 39.3; mang., 0.006 ; sulp., 0.008 ; phos., 1.27; insol.,
28.20. The ore from the pit floor : Iron, 47.7 ; mang., 2.97 ; sulp., 0.05 ; phos.,
0.33 ; insol., 12.60. Crane Iron Co.'s analyses are given on p. 46, D5-
f Analysis of black clay (called "blue ochre") by Dr. Genth : Loss by
ignition in closed crucible (water), 4.84 ; ditto in open crucible (graphite),
4.26; quartz, 44.50; combined silica, 26.25; alumina, with traces of ferric
oxide, 17.95 ; magnesia, 0.94 ; alkalies etc. (not determined), 1.26 = 100.
(D, p. 32.)
$ The quantity of manganese in the ore is surprising. An average sample
of ore taken from the Ironton RR. Co.'s .wharf, analyzed by McCreath, gave :
Iron, 26.40; manganese, 17.65; sulphur, 0.01; phos., 0.09; insol., 21.86. (D243.)
344 GEOLOGICAL SURVEY OF PENNSYLVANIA.
Local beds of black oxide of manganese has occurred
twice ; one in 1872 over a part of the limonite yielded a
good many tons ; another in 1875, in the deepest part of
the mine, just over the limestone floor, yielded several hun-
dred tons ; just over it a red clay separated it from the
overlying limonite.*
P. Brown's mines, 70' deep, is only 100' from the east
end of the great Ironton mine, and lies exactly in the center
of the trough ; ore-breast 30' to 40' high at W. end, con-
sisting almost entirely of pure ore, with intermingled
damourite slate and clay and more or less allophane.f
White damourite clay, in the east wall, under the in-
cline-plane contains lignite (carbonized wood) and fossil
leaves ; a beecTi nut has been found in it ; of course of post-
tertiary age. The clay -lies on the ore and is a deposit of
human age ; whatever the age of the ore may be ; but proba-
bly both are of the latest geological age, and in fact de-
posits in a cavern, which has lost its roof. Black clay
(Uticaf] overlies the ore thickly in the N. wall, but has
been swept away from the south wall.:}:
The limestone floor beds dip S. E. and N. W., in such a
way as to make a synclinal basin or trough, which runs
east, south of Hitter's mine ; and this trough holding the
ore mass and sinking westward towards the head of the
cove, makes the ore mass greater and deaper westward.
There are signs of exhaustion, unless ore be found W. of
the road to Balliettsville ; and eventually in any case in
that direction the edge of the slate belt will cut the ore
* Mostly shipped to Johnstown for spiegeleisen. Analysis of average
specimen by McCreath, Mang. binox., 77.96; mang. ox., 4. 32; ferric oxide,
3.66 ; silica, 4.84 ; alumina, 0.71 ; baryta, 0.15; lime 0.77 ; magnesia, 0.24; soda,
0.37 ; potassa, 3.04 ; cobalt ox., 0.39 ; nickel ox., trace; copper ox., trace ; phos.
acid, 0.15; water, 3.98. A picked specimen gave mang. binox., 84.88-fox.
3.77; cobalt ox., 1.68; lime, 1.90; mang. 0.79; soda, 0.19; pot., 3.50; water, 4.38
(D2, p. 42.) Manganese appeared at the surface near the Big Spring, W.
of Trexlertown. (H. D. Rogers, 1858.)
f A very fine white and sky blue stalactitic hydrous silicate of alumina,
vitreous or resinous, waxy or pearly, found in masses at the Cornwall
mine ; at Jones' mine near Morgan town, Berks county.; at the Friedensburg
zinc mines ; and here.
\ For mining prospects and analysis see D2, p. 44.
IRONTON LIMONITE MINES. 345
mass off, for "at no point hitherto has the ore been fol-
lowed in under the slate."
Ironton is at the W. end of the mine, and the cove of
limestone is made by the projection E. of a sharply pointed
I>rong of slate (III) more than a mile long ; the real syn-
clinal of the district ; the trough in the cove being a mere
local roll, although a large one,*
The Ironton RR. CoSs Kennel mine, and the H. Mickley
abandoned and exhausted, lie to the south of the slate
prong and 1000' from it. Damourite white clay and Utica
black clay in the latter. The former mostly yellow plaster
clay, but some white, and a little black clay overlying the
white; a little ore visible in contact with and under the
black clay.^
The great Siegersville limestone cove, further south, con-
tains many mines, none of them less than half a mile from
the edge of the slate belt, and most of them a mile or two
from it. They are all described in D2, pp. 34 to 39 ; many
abandoned; some mere wash ore; most of them showing
white clay.
8. Sieged s mine at Siegersville, worked at E. end. has a 6
inch ore layer under the sod ; then 12' barren ; under which
ore bed 2' to 4' ; ore in shaft in floor reported 40' thick ;
*But, as an illustration of the difficult geology of the limestone belt, ob-
serve on the map the long (N. E. and S. W.) line of observed limestone
dips obliquely crossing the point of the slate prong, and reading only 32, 23,
28, 320, 120 ( a t the point), 11, 22, 25, 32, 24, 8. JE. Even the violent
theory of a collapsed overthrown and flattened down synclinal will not ex-
plain so puzzling an exhibition. It almost justilies the theory of the non-
eonformability of III upon II. To increase the embarassment there are dips
of N. E. 17 and 28 in the slate pronrj along the high road. (See the fine
colored map of the Ironton mines in D2, pocket.)
t A remarkably beautiful colored geological sheet map of the Ironton
group of mines and slate prong which separates them may be found in a
pocket to Report D2, 1878. The limestone in the mine floors, the ore masses,
the red, white, yellow, and red clays, and the undecomposed slates are all
distinguished by separate colors. The depths are shown by contour lines,
which are also extended over the whole sheet. It is a rarely perfect exhi-
bition, on a scale of 300' : 1" of an unusually complete piece of difficult field
work. It is dated 1875, and is the work of Mr. Ellis Clark, Jr., aid to Prof.
Fred. Prime, Assistant Geologist in charge of the Survey of the Lehigh
region.
346 GEOLOGICAL SURVEY OF PENNSYLVANIA.
much lump ore and blood red clay ; in one place limestone
over the clay, the limestone "thorough!} 7 permeated by
damourite.*
Jas. Kline's mine, at Orefield, m. S. of Siegersville, is
within m. of the N". edge of the long syrcelinal slate prong
which runs out eastward four miles, eastward N. of Wen-
nersville. Most of the ore is extracted. AtN. E. corner soil
20' deep ; then red ore bearing clay 10', then yellow and
white clays streaked with ore ; very little lump ore found.
Damourite slate sticks so closely to much of the ore that it
cannot he separated by washing. White clay both above
and beneath the ore. At W. end, soil M^feet ; then all
white clay down to standing water, with a good deal of
only partially decomposed damourite slate in the clay.
Yield of mine has been great.
B. Weaver's mine, I m. E. of Orefield and Guthsville,
and. just on the north edge of the slate prong ; 40' deep ;
near top damourite slate with white ore clay underneath ;
atN. end damourite slate holding thin strings of ore, but
the ore mass is beneath it ; slate resembles No. III.
The Thomas I. Go. and Crane I. Go. and D. A. Guth 1 s
and the two Wanner mines range eastward along the north
side of the slate prong. They have furnished large quanti-
ties of ore, but are exhausted. At Guth's mine limestone
is seen dipping S. E. towards and under the slate prong ;
but the Utica slate (?) seems to dip N. W.
Toward the end of the slate prong are six mines : Kratzef s,
Jobsfs (2), and Scherer' s, on the north edge of the slate
prong ; Marck's at the extreme point ; and Barber and Al-
ney' son the south edge near the point. In these are seen
pinkish damourite slate, and sometimes a black slaty rock
which may stand for the Utica. The whole range are
abandoned.
In the next limestone cove 3 m. IS". W. of Trexlerville, there
are about 15 mines, mostly abandoned^ all but one within
*This either shows a cavern deposit of clay, or proves the decomposition
of damourite layers far down the stratification beneath an insoluble roof
of limestone beds.
LIMONITE MINES NEAR THE TOP OF II. 347
i m. of the edge of the slate : LichtenwallnerX Loros'
(two), Stein's (two), Moyer s, Steininger's (two), Scholl
&Co.'s, Miller's (two), and Haines' and Smith's (Schlong's),
the last two in front of the east point of the slate prong
which shuts in the cove.*
In the centre of the Cove a mile from the slate edge
Krsemlich & Lichtenwallner'smine (D. p. 42), 50' deep, not
worked since 1873, has its ore mass lying on horizontal
blue Limestone, probably the flat crown of the anticlinal of
the cove. There is evidently a large amount of damourite
slate and white clay underlying the ore and in some places
inside of it. If we could tell the shape of the arch, this
would settle the question whether or not some of the Le-
high limonites were made from damourite sub-formations
in the body of No. II. But if the arch is flat, or subdi-
vided by a synclinal, the damourite clays in this mine
may also belong to the slates at the top of II.
At the head of the next shallow limestone cove and close
against the edge of the slate belt, l^m. N. W. of Breinigs-
ville, is Fr. Breinig* s large exhausted mine, 50' deep ; but
a small pit on the east of it was still worked in 1874 ; ore
streaks in damourite slate and white and yellow clays ;
ore and clays pitching 18 to 25, S. 80 E. away from the
slate belt! And yet a glance on the large sheet map of D2
is sufficient to show a bridge of slate (III) thrown across
*In Lichtenwallner's pits (one 40' deep) the ore lies both on and under
white clay over damourite slate ; blue limestone reported at the bottom of
a well 130' deep. At Loros's mine a gravel of clay, quartz and slate (all in
small pieces) 15' deep covered the west end. Stein's oldest mine must have
had a great output. The other leased to the Thomas I. Co. shows no slate ;
the ore lies in and over white and pink damourite clays 47' deep ; limestone
at 40' in one place dips 42, S. 41 E. (top layers drab slaty 4', laying on
common blue limestone water worn); ore clays over the limestone dip 42,
S. 40 E. A hole 10" square in the floor drains the mine into some un-
known cavern. Moyer'' s, a new stripping (1875). Steininger's old mine ;
very productive ; 600' x20' deep ; exhausted. The other leased by Lani-
gan, 25' deep ; ore in damourite slate overlying white clay, dipping 22, S.
40 E. In one place under 12' of solid white clay is ore 6', then clay 12'.
Scholl & Co. 's ore in rolling clay ; general average dip 10, S. 5 E.; local
dips, to S. W. (one of them 55, S. 25. W); output 25 tons per day (1883)
Miller' 1 s, abandoned, described by Rogers (1858) as ore interstratified irre-
gularly with clay. Haine's, abandoned Smith's, 40' deep, described by
Rogers as Schlong's, in damourite slate.
348 GEOLOGICAL SURVEY OF PENNSYLVANIA.
LIMONITE MINES NEAR THE TOP OF II. 349
Section along Cornwall Railroad
from Isebanon to Miners' Village.
Section acraalSig Hill combined wdk Seclwn cdang Furnace creek.
them Iraf dUUrla itt relaiiantkip io Creek section.
CnvyXU
OR i-MA5S
Seal*. rtHical and Jinriifntal alUa . &OO fe*t, lo 4 inch.
""" J.U&
350 GEOLOGICAL SURVEY OF PENNSYLVANIA.
the limestone of the cove (II) and isolating the head of the
cove as an enclosed limestone circus in the body of the
slate belt. This abnormal dip must therefore be a sag of
the decomposed ore-mass into some cavern in the limestone.
The Trexlertown Copperas mine deserves mention here
for the bore hole records preserved in Rogers' Geol. Pa.,
1858, p. 265 ; 1 m. W. of Trexlerville ( m. N. E. of Brein-
igsville) ; worked in 1836-1840 ? by N. Whitely.
Boring No. 1 recorded : Clay and gravel, 30'; iron ore,
4|'; clay. 7'; black clay, 2'; sulphur et of iron (pyrites], 12';
iron ore, 5'.
Boring No. 2: clay and gravel, 15'; iron ore, 1'; clay,
15': slate, 5'; clay, 6'; pipe ore in clay, 9' / clay, 4'.
Boring No. 3 : clay, 14'; iron ore in clay, 8'; iron ore, 9';
clay, 3'; copperas earth, 2'; copperas in black clay, 2'; cop-
peras in white clay, 2'; brown clay and iron ore, 8'; solid
iron ore (pipe?), 2'; clay, 8'.
Manganese oxide appeared in the west wall. The slate
mentioned in No. 2, was made somewhat gypseous by the
reaction of the sulphate of iron on its lime element. "The
origin of this large deposit of sulphuret of iron," says Mr.
Rogers, "is to be traced probably to a small shallow bed
of Matinal [Utica] black slate which appears to have rested
on the limestone and to have undergone disintegration."
But if this opinion is correct we may extend the expla-
nation to most of the other limonite mines in the central
area of the limestone belt.
The Moselem mine in Berks Co.
This famous old mine, 5 m. W. of Kutztown, is within
1000' of the edge of the slate belt, and corresponds exactly
to the great Ironton mine. The ore was reached at first by
shafts through surface stuff 20' to 40' deep. Immense
quantities of good ore were mined from nests and irregu-
lar layers varying from V to 8' thick ; some of it bluish and
slightly manganesian. Limestone beds in the ridge south
of the mine dip northward, as they should, under the ore,
and (if continued] under the slate belt. Large quantities
of dark chept, some of them hundreds of pounds inweight r
THE MOSELEM MlNE. 351
lay scattered over the soil. (Rogers' Geol. Pa., 1858, p. 226.)
In 1878 the mine was surveyed by A. P. Berlin, in common
with the whole valley between the Schuylkill and the Lehigh
county line. It was then 2000' long and 100' deep, with
five inclined planes. (See Fig. 1, on plate VIII.)*
It is certainly a surprising circumstance that this great
Moselem deposit should stand alone ; that nothing like it
appears for so many miles along the edge of the slate belt in
Berks and the counties to the west of it. One is tempted
to suspect great local variations in the thickness or rich-
ness of the upper damourite slate formation. Or perhaps
a mechanically produced non-conf or mobility has shoved
the damourite slates beneath the slate belt edge. But
more probably the only and sufficient explanation is, that
only here and at Ironton and a few other places caverns
have been eroded to receive the iron drainage. Vague as
this suggestion may seem it is borne out by such exhibi-
tions as the Pond banks of Franklin county ; and by the
cavern deposit of Penns valley in Centre county, to be de-
scribed in another chapter.
The Cornwall mine.
This summary description of the Lower Silurian Forma-
tion No. II would be incomplete without a special mention
of one of the most important mines in Pennsylvania, the
great magnetic iron ore mine of Cornwall, in Lebanon county,
unique in its character, standing alone in the geology of
*Fig 2 on the same plate is a reduction from Sheet XIV, of the great topo-
graphical map of the South Mountains (Reading and Durham highlands)
published in the Atlas to Report DH, Vol. 2, 1883. The survey of the lime-
stone belt was made by Mr. A. P. Berlin in 1878. The small portion of it
given in Fig. 2 illustrates the flatness of the limestone belt; the steep hill-
side edge of the slate belt, through small gorges in which its back drainage
issues upon the limestone belt; and the close proximity of the great limo-
nite deposit to this outcrop wall. At the the east edge of the figure the
reader will notice the normal 36 northwest dip of the limestone descend-
ing beneath the slate belt in the ravine; also northwest and southeast (anti-
clinal roll) dips in the quarry east of the ravine ; also an 18 northwest dip
in the little quarry west of the ravine; and other northwest dips around
Leibensperger's ; so that the geological place of the ore slates is unmistakably
at the top of II under the slates of III, with no evidence of non-conform-
ability between the two formations.
352 GEOLOGICAL StJRVEY OF PENNSYLVANIA.
THE CORNWALL MINE.
354 GEOLOGICAL SURVEY OF PENNSYLVANIA.
the State, arid pouring year after year its flood of wealth
into the business world. Worked for more than fifty years,
it shows no sigh of exhaustion ; on the contrary, its annual
output continually swells in volume.
Three hills of ore three hundred feet high, are ranged in a
line a mile long and a third of a mile wide. Walls of solid
ore 80 feet in vertical height are stoped down by dyna-
mite ; and the fragments, broken up to portable sizes, are
loaded in cars and distributed to the iron furnaces of the
region. A floor of the solid iron ore at water level conceals
an underlying ore-mass, into which test holes have been
bored varying in depth from 50 to 300 feet. A great vol-
canic trap-dyke, like the half of a cup, supports the ore-
mass at its northern edge, and has been proved by some of
the bore-holes to be its floor. Along the southern edge runs
one of the few great faults of the State, limiting the ore-
mass on that side. Against this fault descends (northward)
at a gentle slope the Mesozoic beds of northern Lancaster,
their sheared-off edges making the southern side of the cup
which holds the ore-mass.
It is this unusual occurrence of Mesozoic red sandstone
faulted against the limestone formation of the Great Valley,
with an outburst of ancient lava rising through the crack thus
produced and making its way sidewise between the limestone
strata, lifting them and holding them isolated, as in a vat
in a chemical laboratory it is this unusual combination of
circumstances which has given its unique character to the
Cornwall iron mine. The mine has been a puzzle to geolo-
gists ; and a satisfactory explanation of it has been only
recently obtained by a laborious research upon the ground.
It is now made evident that the whole ore-mass was orig-
inally a set of lime-shale strata belonging to the very top
of Formation No. II, which we may call the passage beds
between No. II and No. III. These beds, held between
the two walls of Trap and Trias, have been attacked by hot
acid waters flowing into them, dissolving away the carbon-
ates of lime and magnesia, and leaving behind in a concen-
trated mass the insoluble silicates and hydrated peroxide
of iron, converted much of it into the magnetic oxide.
THE CORNWALL MINE. 355
The whole mass of ore is distinctly stratified, and shows
the process of concentration. The original insoluble matters
in the lime-shale still remain in the ore. The stratification
of the ore-mass is perfectly regular ; but almost unchanged
white crystalline limestone beds lie interstratified in the
midst of it, showing that some of the original strata had a
mineral composition not susceptable to a change into ore.
These limestones lie in their original places among the other
strata which have been changed into ore. But they have
been subjected to merely enough change to convert them into
an inferior kind of crystalline marbie. The rest of the ore
strata were no doubt first charged with hydrated peroxide
of iron (brown hematite) ; but the change went on one step
further; the water was driven off, and the oxide of iron was
crystallized into magnetic iron ore ; still retaining all the
impurities of the original lime-shale beds.
The remarkable features of this ore mass are : First, the
quantity of sulphur which it contains ; and, Secondly, the
universal distribution of a small percentage of copper
through the whole mass of ore ; and its concentration into
strings and plates of native copper only in the upper part
of the mass where attempts were made at one time to ob-
tain it in sufficient quantities to make it marketable ; but the
richest pockets of it at the top of the hill were soon ex-
hausted, and none others have been met with lower down.*
*The origin of the copper, and of the sulphur also, has been connected
with the outburst of trap, and also with the neighborhood of the Triassic
sandstones, but the subject is still entirely obscure. Nor is it of practical
importance, for all attempts to mine copper in Pennsylvania have signally
failed. But to geologists the question of the origin of the copper in the Corn-
wall ore is one of high interest. At present the only facts which we can bring
to bear upon it are those connected with the old copper operations at the edge
ol the Mesozoic sandstone in Chestercounty westof Norristown; and these are
not sulllciently understood to throw much light upon the subject It is
remarkable that the mines near Dillsburgin York county furnish the same
kind of copper-bearing magnetic iron ore as that at Cornwall ; that they are
surrounded by Mesozoic red sandstone near its present northern edge; and
that outbursts of trap similar to the trap enclosure at Cornwall are also in
contact with the Dillsburg ore. Similar ores are also mined on Fritz's is-
land in the Schuylkill near Reading, and at Boyertown and at Seitzholtz-
ville further east in Berks county, where copper and trap again accompany
the ores. All this suggests, although it does not prove, that the copper has
come in some form, perhaps as vapour, with the fluid lava from the interior
350 GEOLOGICAL SURVEY OF PENNSYLVANIA.
I do not propose to repeat in this summary of the geol-
ogy of the State the very full description of the Cornwall
mine published as a separate memoir in the Annual Report
of the Survey for 1885, pages 491 to 565, with maps and
sections and page, plate diagrams, showing stope-faces,
the structure and the construction of the ore-mass. In
lieu of verbal descriptions I give the more important of
these illustrations, greatly reduced, but legible enough to
make the whole thing comprehensible.*
The geological situation of the Cornwall mine and its
railway connections with Lebanon are shown by Fig. 3 on
Plate IX.
The reason for placing it geologically at the top of II in-
stead of at the bottom, although it is on the southern in-
stead of the northern edge of the limestone belt, is made
clear by Fig. 1 on Plate IX, which represents a cross-section
of the belt (looking east) from the edge of the slate belt to
the edge of the Trias country. The vertical rise of the top
beds of II at Lebanon, their flattened rolls across the belt,
and their descent at Cornwall, require no commentary, f
of the earth ; and it is possible that the sulphur accompanied it On the
other hand we have copper shales in the Devonian formation of the northern
counties of the State a hundred miles from any trap, and several miles above
the plutonic floor. But one of the most conclusive proofs that the Cornwall
and Dillsburg copper has no necessary connection with either the Trap or
the Trias is found in the facts mentioned on a previous page, namely, that
similar leaves and strings of native copper are found in stripping the black
clay from the limonite ore mass at Ironton, which is not at all magnetic, has
no trap near it, and is in fact a simple leaching from the upper damourite
slates at the edge of the slate belt It looks as if the sea-water of that age
was heavily charged with soluble salts of copper, as the water of the Medi-
teranean Sea is now. As for the abundance of sulphur, it is only necessary
to allude to the many red-short ores of our back valleys, far from any
source of heat ; but especially to the account given on a previous page of the
Copperas mine between Breinigsville and Trexlersville in Lehigh county.
*The reader may find a condensed statement of all the facts, and a num-
T>er of their illustrations, in Mr. E. V. d'Invilliers' paper read before the In-
stitute of Mining Engineers at its Pittsburgh meeting, Feb., 1886, and pub-
lished in its Transactions. I assisted Mr. d'Invilliers by a personal examina-
tion of the mine, and am responsible for the theoretical conclusions to which
he did not yield an unqalified assent, and at which other competent geolo-
gists may demur. Cornwall must continue to be for many years a theme
for discussion.
f I have in a previous chapter described similar descents of the slates of
III along the south edge of the limestone belt in Cumberland and Dauphin
PATH. VALLEY MINES IN FRANKLIN COUNTY. 357
Cross-sections of the ore mass and trap are given in Fig.
2, Plate IX, and Fig. 1, Plate XI ; and a section lengthwise
through the three ore hills is given in Fig. 3, Plate IX.
A reduction of D'Invilliers' topographical map of the
whole mine (in part) is given in Plate X. The most strik-
ing feature of this map is the trap liook at its eastern end.
I can imagine no other explanation for this most interesting
structure than that suggested in the memoir in the Annual
Report, viz : that the ore-mass really represents a body of
limeshales thrown into a sharp and deep synclinal, and
that the out* and up-flowing trap followed the synclinal
bedding. This south side of the synclinal trough was
sheared off by the fault, and, therefore, the trap hook stops
at the fault. But this leaves unexplained why the trap
did not follow up the fault to the present surface, and pre-
ferred rather to rise sidewise (N.) between the beds.
The curious tongued structure of the trap on the north
edge of the Big Hill shown in Fig. 3, Plate XI suggests
that we are thece not far from the extreme limit of the trap
ejection upwards.
The outcropping unchanged limestone beds in the body
of the ore mass are shown in Fig. 2, Plate XI.
Patli Valley mines in Franklin County.
Path valley is an anticlinal limestone cove in the north-
western side of Franklin county, extending for about ten
miles in a 1ST. E. and S. W. direction along the eastern base
of that portion of the North mountain locally known here
under the name of the Tuscarora mountain. It ends on
the S. W. in a cove between this mountain and an outlying
spur known as Bear Knob, while to the N. E. the anticlinal
counties. Another occurs in Lebanon county east of Cornwall. But the
most extraordinary instance is to be seen at Reading, where a north and
south belt of III is colored on d'Invilliers' map as intervening between the
Schuylkill and the mountains back of Reading. How the structure here is
to be explained I can only conjecture by supposing a westward slip of the
valley rocks from over the mountain gneiss. At the beginning of Chapter
XXVI, I have described the east dips of the limestone in the quarries at
Reading, but I omitted to notice this belt of overlying slate, which Mr.
d'Invilliers has no doubt of being No. Ill, and not primal slates.
358 GEOLOGICAL SURVEY OF PENNSYLVANIA.
lies about midway between the Round Top and Dividing
Mountain spurs. The limestone of No. II is exposed in
this valley between Doylesburg on the IS". E. and the Rich-
mond furnace on the S. W. and is nowhere over two miles
wide, tapering toward each end. The north dips toward
the mountain flank are usually somewhat steeper than those
on the south side of the axis, especially for a distance of
six or eight miles in Metal township, owing largely to the
presence of a fault along the base of the mountain, which
swallows up a large portion of the No. Ill slate formation,
and opposite Fannettville brings the limestones of the val-
ley within close proximity to the mountain sand rock No.
IV. Along this line the dips are often vertical, if not
overturned to the S. E. and it is mainly in this portion of
the limestone area, near the junction of Nos. II and III,
that the iron ores of this region are exposed and developed
for a distance of about eight miles between Richmond fur-
nace and Fannettville. The South Pennsylvania branch
of the Cumberland Valley railroad was originally con-
structed to reach these deposits, which were then thought
to be of great extent and purity, but which after a consid-
erable development, have proved a source of expensive dis-
appointment to the projectors of the road and those inter-
ested in the resources of that region.*
Richmond bog ore bank at the S. W. end of the range,
3000' N. of Bear Knob ; long abandoned, 20'x20'xlo' deep 5
uniformly good rich non-phosphatic ore, but not much of it.
Mount Pleasant bank, the oldest and largest of this
range ; two open cuts separated by barren clay partition at
S. W. end and uniting in one large open cut at N. E. end
towards Cowan's Gap. Southern cut still 250' x 100' x 60'
deep, although a good deal filled up since its working was
abandoned. A 60' high steep barren red-sand-wash wall
on the S. E. in which a few decomposed layers of sandstone,
with steep (overturned ?) S. E. dip, appear above the con-
formably dipping limonite. On the N. W. side, the divid-
ing partition is largely of white, bine and yellow clays.
*DTnvilliers in Annual Report 1886, part IV, page 1490. The following
description of the banks is greatly condensed from pages 1401 to 1501.
PATH VALLEY MINES IN FRANKLIN COUNTY. 359
Behind the partition dense close-grained limonite under
sooty-black clay ; left in wall a N. W, dipping lens-shaped
bed 10' to 20' thick, interrupted by barren clays. Total length
450'. On the mountain side 8' to 20' of stripping stopped
work in that direction. Total output said to be 100.000
tons. Analyses: Iron, 47.5; manganese, 2.3; sulp., 0.05;
phos., 0.34 ; silicions matter, 11.7.
Beaver bank, 2500' N. E. of last; 200' x 150' x 20' to 40'
deep ; bed of limonite 20' thick said to be left along E. wall.
A rib of barren iron stained sandstone extends through
the middle of the oval open cut ; and another shows in the
N. W. (mountain) wall, through which a drift reached
some good ore. No black clay ; all the barren stuff is red.
Whole output 10,000 tons ; ore very irregularly scattered ;
well 80' deep in floor, said to have gone through good wash
ore.
McGowan pit, 1000' N. E. of last ; small, irregular ; all
wash ore ; no black clay ; less red than white and yellow
clay. Worked long ago. Other small pits, abandoned ;
one 20' deep said to have been all good lump ore.*
Well up the mountain side, N. W. of the banks at the
foot of the slope just described, is another range of banks :
Old Johnson bank ; furnished say 500 tons of ore mixed
through a sand and clay wash.
Lessig pits ; the one furthest (N. E.) yielded say 200 tons
of slaty cold-short ore. From the other pits, 10' to 18'
deep, clean good limonite, say 50 tons in all. The outcrop
runs straight across both tracts and would yield some ore
here and there if opened.
Car rick 1 furnace has a run of 1^ miles on the outcrop
further N. E. First pit 50'x'30'xlO / , yielding considera-
ble good ore ; shaft 10' deep in floor stopped in ore. Porous
wash ore making tough iron shows in the bank wall under
7' stripping. Two other pits (600' N. E. of last), 50'x25'x
15'. gave say 500 tons of ore condemned at the furnace. f
*The banks described above are on S. Pa. M. & R. R. Co.'s tract of 6000
acres. The company holds leases on several thousand acres more ; but
the field is practically abandoned.
f This is a curiously interesting illustration of the variation in quality in
limonite along one and the same outcrop line.
360 GEOLOGICAL SURVEY OF PENNSYLVANIA.
After many smaller pits comes a large one, lOO'xSO'xSO': a
25' shaft in the floor produced excellent lump ore. No
water here ; water scarce in all the pits ; pits therefore often
abandoned even when good ore could be got. Another cut
(a little lower down the slope) 300' N. E. of last ; 150'x50'x
20' ; slope (very old) put down 20' on N. W. side in good
lump ore.
Old Carrick bank, % m. further on N. E. and just in front
of the Wind Gap by which the road passes over into Hunt-
ingdon county. Here only the top of No. Ill crops out,
all the rest of the slate formation being swallowed, up in
the fault * and the ore mine 300'x40'x25' runs along the
fault and close to the limestone. A shaft 125' deep sunk in
the mine floor is said to have passed through a steeply dip-
ping 30' to 35' ore bed. Another shaft (at W. end) is said to
have gone 75 feet through this ore and stopped in solid
lump-ore. Yet the whole place is abandoned and dilapi-
dated. Most of the output came from gallery workings N.
E. and S. W. of the ravine. All the wall towards the
mountain shows soft sooty black clay, like that which caps
so manv of the mines along the foot of the South mount-
ain. Four sets of lessees have worked the mine ; output
estimates vary so as to be worthless. Analyses of samples
of ore used by Carrick furnace in 1880: (1) lump ore:
Iron, 45.3; mang., 1.1 ; sulp., 0.05; sil. mat., 16.3 ; phos.,
0.36 (2) wash ore : 36.4 ; 1.7 ; 0.06 ; 26.0 ; 0.27.
Railroad bank (Carrick Fur. Co.) 1200' further N. E.
than last ; 400 / x40 / xl6 / ; not much ore visible in 1886; strip-
ping very heavy; shaf t 'under S. E. wall 40' (reported) en-
tirely in ore, and in drifts to N. and W. Bank must have
had a very large output. Analysis of a sample picked
up: Iron, 43.6; mang., 0.24; sulp., 0.005; sil. m., 18.5;
phos., 1.482 (unusally large).
A few more pits are seen further on N. E. beyond the
Fannettville road ; outcrop distinct for more than a mile ;
G. Umbril's abandoned pit being the last.
A short distance E. of Mercersburg are three small banks,
*Henderson's fault, as we used to call it, because discovered and described
by A. A. Henderson of the First Geol. Survey of the State 1839-40.
THE IIENRIETA MINES OF BLAIR COUNTY. 361
Leib's, Stauffef '?, McFarland 1 s, now abandoned, which
yielded some good bog ore.
Stinger's old pits at the mouth of Bear valley, 1 m. E. of
London, and on or near the II-III line ; long abandoned ;
analysis: Iron, 39.5; mang.,4.8; sulp., 0.04; sil. m., 18.8 ;
phos., 0.61.
Garlic BankE. of last (2 m. S. W. of St Thomas) ;
200'xlOO'x20'; walls of red clay carrying fine ore and a little
lump; not worked for 15 years (1886) ; too far from RR. ;
good ore; analysis: Iron, 52.9; mang., 0.08; sulp., 0.15;
sil. m., 6.89 ; phos., 0.06.
In the other direction 2 m. W. from Mercersburg, the
Webster bank is on a II-III contact line ; abandoned.
The Henrleitamines of Blair Co.
These limonite deposits are the only others to be described
in this chapter as appearing to have a geological horizon at
the top of II, in contact with the slates of III, and along
lines of fault like the Path Valley mines in Franklin
county last described.*
Leather cracker Cove is made by an anticlinal of No. II
limestone, faulted on both sides, so that the arch is thrown
up 2000' and rests against the slates (III) and the sand-
stones (IV) of Tussey mountain to the east, and of a small
slate ridge (III) to the west. The big fault (the eastern one
at the foot of Tussey) is about a mile long, and approxi-
mately parallel with the strike of the country. The anti-
clinal runs on N. 20 E. to and through Canoe Valley in
Huntingdon county. See Fig. A in Report T, p. 91.
* I am loth to mix these up with the great mines of the Great Valley, and
to separate them from the regional mines of Nittany Valley and Morrison's
cove ; but they are the only notable mines in middle Pennsylvania behind
the Great Valley referable to the top of II, when I made my last
survey of that iron region ; all the other limonite deposits of II being re-
ferable to various horizons in the body of the formation. But it will ap-
pear in a subsequent chapter (XXXIV) that I now place a different inter-
pretation on that fact, and believe that the Henrietta ore horizon is only ac-
cidentally connected with the slates of III by reason of a great upthrow
fault
362 GEOLOGICAL SURVEY OF PENNSYLVANIA.
lALap cft/te SaticonZinc TTtlnes cuici vicinity. ~Pl. XII .
THE HENRIETTA MINES OF BLAIR COUNTY. 363
The line of contact limonite ore deposits runs from the
Henrietta bank due south. At the south end of the line
of ore the Oneida terrace (IVa) and the Hudson river
slates (UK) are swallowed by the fault.* It seems a logi-
cal conclusion that this line of limonite ore has been pro-
duced in some way by the fault. The contact of II and III
is sharply defined along Tussey mountain its whole length
across four counties, and along Dunnings, Lock, Loop,
Canoe, Bald Eagle and Nittany mountains, for about a hun-
dred miles of outcrop. Almost every ravine cutting
through the terrace of slate into the limestone valley affords
as good an opportunity as could be desired for finding any
ore deposits existing at the contact of the two formations,
or produced by the decomposition of lime-shale beds of pas-
sage from limestone to slate. In most cases the cultivated
fields at the base of the mountain would betray the pres-
ence of such ore deposits. In spite of all this however not
a single such discovery of any importance has been reported,
except in Leathercracker cove. The conclusion is obviously
good that the Henrietta ore mines occupy this geological
horizon exceptionally, by accident, and solely in virtue of
the Leathercracker faults.
But this conclusion has a wider range and applies forc-
ably to the Great Valley, where we see the Path Valley
deposits of Franklin county lying along just such another
fault ; and then we must go 140 miles along the middle con-
tact line II and III before we reach the Moselem mine in
Berks county, where we have seen there is some reason for
suspecting a faulted structure. In the Ironton region of
Lehigh county there is scarcely a single mine which can be
assigned with certainty to the contact of II and III ; and
from Ironton eastward no deposits of limonite can be
proved to overlie the Trenton. Even at Cornwall there is
solid limestone (Trenton ? ) at the very top of the ore shale
mass. Remembering that no limonite appears with the
passage beds in the bends of the Conedogwinit in Cumber-
land county, and keeping always in mind that we have as
*A11 the arguments for the fault are given successively in detail in T,
p. 90, to which the reader is referred.
364 GEOLOGICAL SURVEY OF PENNSYLVANIA.
yet no assistance from fossil forms in determining the true
position of any limestone or lime shale beds faulted against
the slates of III at Henrietta mine or elsewhere, it must be
regarded as quite possible that all our Great Valley limo-
nites are cavern deposits of very recent date derived from
the decomposition of a series of damourite lime shales be-
longing to various horizons in the Magnesian limestone for-
mation, that is, the Chazy and Calciferous.
In the next chapter such horizor^s will be exhibited.
NITTANY VALLEY LIMESTONES NO. II. 365
CHAPTER XXXI.
Nittany Valley limestones, No. II. Centre County anti-
clinals. Nittany Valley cross -sections.
The ore horizons of the Great Valley have been seen to
be obscured by the folded and crumpled condition of lime
stone and slate belts. In Nittany, Brush, Penns, Canoe
and Kishicoquillis valleys, and in Morrison's, Friend's and
McConnellsburgh coves, a simple anticlinal structure, dis-
turbed by only a few faults and hardly at all crumpled,
makes the order of the limestone beds an easier study,
sufficient to establish the different horizons by approxi-
mately parallel ranges of ore banks.*
The great rock waves of Middle Pennsylvania are splen-
didly exhibited in the McConnellsburgh Cove in Fulton
county, with its 8000' fault on the western side ; in Kishi-
coquillis valley in Mifflin county, with its surrounding ter-
race and eastern keel-shaped mountain prongs ; and most
of all in Nittany valley and Morrison's Cove (united by
Canoe valley) where the grandest anticlinal of the State
brings to the surface the whole of the magnesian limestone
(capped by 400' of Trenton limestone) with immense de-
posits of iron ore. A description of the Nittany anticlinal,
and of the subordinate waves which broaden and spread out
its southern slope, is a necessary preliminary to the descrip-
tion of that oldest and richest iron ore region of middle
Pennsylvania.
Centre county anticlinals.
The great Nittany valley anticlinal, which brings to the
surface the top layers of No. II in Mosquito valley in
*Mr. D'Invilliers in Report T4, p. 137-8, says that the popular belief in
continuous belts of ore-producing territory along fixed outcrop belts or
horizons was not confirmed by his survey of Centre county ; but this does
not invalidate the statement that limestone horizons are demonstrable, and
ore horizons approximately so.
366 GEOLOGICAL SURVEY OF PENNSYLVANIA.
Ft. XIII.
&WM Section* tfJfoJl in Jfittaivy Valley, GemtivGo.
Chestnut ndge taledwy'rirfye-..
zfetD
CENTRE COUNTY ANTICLINALS. 367
Lycoming, and Nippenose valley in Clinton, rises in Cen-
tre county so as to expose on the Centre-Huntingdon line,
west of Bellefonte, at least 6000' of the formation, without
however bringing the bottom beds to the surface.*
Continuing S. W. across Huntingdon into Blair at a still
higher elevation it exposes more than 6000' of No. II down
to (or nearly to) the bottom beds at Birmingham on the
Little Juniata. Then it sinks rapidly to the head of Sink-
ing Creek valley, where the slates of III close over it, and
the mountain rocks of IV, the Frankstown fossil ore red-
shales of V, and the Hollidaysburg limestones, etc. cover
it; and so it runs on south through the Devonians into the
coal measures of Somerset county.
The Gatesburg ridge anticlinal in Centre county runs
parallel and 1J miles to the S. E. of the Nittany (Chestnut
ridge) anticlinal ; and becomes the Hickory ridge anti-
clinal of Huntingdon county, crossing Half Moon creek 2
m. N. of its junction with Spruce creek. f
Dry Hollow synclinal lies between the Chestnut ridge
and Hickory ridge anticlinals.
Sand ridge (Tadpole ridge} anticlinal in Centre county,
runs parallel and 1 m. S. E. of the Gatesburg ridge anti-
clinal, and its S. E. dips pass beneath Spruce creek down
into the roots of Tussey mountain. It is the Spruce
creek anticlinal of Huntingdon county. On the county
line, opposite Pennsylvania furnace, it brings to the surface
* D'Invilliers in T3, p. 443 : East of Bellefoute the axis beds are the " Bar-
ren " sandrocks of Sand ridge ; west of Bellefonte the axis runs along Chest-
nut ridge. Its S. E. dips are rather gentle here, but its N. W. dips (in the
Stormstown valley, 1^ miles wide, between Chestnut ridge and Bald Eagle
mountain) are steep, vertical, or even overturned so as to dip S. E.
f This arch is quite subordinate to the great Nittany arch, and is in fact
a roll on the grand S. E. slope of the formation from the Nittany arch crest
towards Tussey mountain. One result is that the Hickory ridge barrens
are not the Sand ridge barrens of Centre county, but are much higher in
the series ; giving us two quite distinct horizons of Calciferous sandstone
strata in No. II. This roll appears to die down rapidly N. E. and S. W.
from Half Moon run, and probably flattens out before reaching Warrior
run ; at all events there is no trace of it in the long exposures of the Little
Juniata. It seems to bring up the particular horizon of shales from which
the Old Seat, Huntingdon furnace, and Dorsey ore deposits were generated.
(D'Invilliers letter of May 18, 1885, in T3, p. 445.)
368 GEOLOGICAL SURVEY OF PENNSYLVANIA.
3500' of No. II ; and it is in this upper half of the for-
mation that most of the pipe ores of the region are mined.*
The Brush valley anticlinal runs along at the S. E. foot
of Nittany Mountain, between it and Brush mountain. f It
passes north of Rebersburg and Madison ville, with N. W.
dips of 65 to 70, and S. E. dips of 15 to 20. Just north
of the Penns Valley cave, pure soft gray Trenton limestone
beds dip 70 N. W. and 45 S. E. It reaches its greatest
height near Centre Hall, where it brings to the surface beds
2500' beneath No. TIL:}: Sinking and flattening S. W. it car-
ries the Watson, Ross, Stover and other ore deposits. On
Spring creek. 1 m. S. of Lemont, its dips are 48 N. W.
and 12 S. E., flattening to 8 at Boalsburg. Then it rap-
idly dies out before reaching the foot of Tussey mountain.
The Penns Valley anticlinal runs south of Brush mount-
ain, between it and Stone mountain, in the slates of III in
Pine Creek Hollow ; lifts the top Trenton beds at Hoster-
man's saw mill, and rims into a cove of Tussey mountain.
TJie Penns Narrows anticlinal barely lifts to the surface
in the Narrows and in George's valley the top Trenton
*This Sand ridge anticlinal axis runs from Pennsylvania furnace (N. E.)
to Johnston's ore bank in College township, lapping past the dying Brush
Valley anticlinal ; and between the two begins the Nittany mountain syn-
clinal which deepens (N. E.) and takes in the slates of III, the sandstone
of IV, and the red shale of V, which make the canoe-shaped Nittany mount-
ain. At Pennsylvania furnace the Sand Ridge dips vary from 25 to 60,
N. W. and 25 to 40 S. E. At Johnston's bank its S. E. dips vary from
15 to 30. (T4, 35.)
f Eastward this axis makes Sand mountain in Union county and crosses
the Susquehanna near New Columbia. Westward it curves from W. toS. W.
just as the Nittany valley anticlinal does, entering Centre county in Miles
township at the head of the narrow Hudson river slate cove with which
Brush valley commences. It brings up the top Trenton beds near Rudy's
mill.
JThis accounts for the ore-poverty of Brush valley; the uppermost ore
horizons on steep dips affording no good opportunity for concentration and
preservation ; and the rest being buried.
It crosses the Susquehanna north of Lewisburg. On e mile east of Aaron s-
burg its limesand beds dip 68 N. 25 W. and 40<-' S. 35 E. It bends
sharply southwards and crosses the pike i m. S. of Millheim, where dips of
70, 640, go N. W., and 12, 20, 30 S. E. are seen. Then it bends and runs
due west to the church, 1 m. N. E. of Penn Hall ; here|m. N. of edge of III
in Egg Hill. North of Spring Mills its dips are 60 N. W., 20 S. E, Gentle
arch at Penns creek ; greatest height 2m. further west on the Bellefonte-
Lewistown pike ; then turns S. W. and dies into the Tussey mountain cove.
CROSS SECTIONS IN CENTRE COUNTY. 369
beds, with dips of 70 N. W. and 60 S. E. Its highest
point is 2 m. W. of the MiJlheim pike with dips of 70 N.
W. and 50 S. E. At Potter's mills are dips of 85 N. W.
and 70 to 80 S. E. It sinks west in the slate "Loop" 4
m. west of Potter's mills, and issues S. W. from Tussey
mountain at the Bear Meadows in Huntingdon county.*
It will be seen from the above sketch of the structure
and from the figured cross-sections why almost all the limo-
nite ore deposits are confined to the Nittany valley proper,
the great arch of which brings up nearly the whole of for-
mation No. II, exposing to erosion and concentration all
its iron-bearing limeshale and limesand horizons.
Cross-sections in Centre Co.
Figs. 1, 2, 3, 4, 5, 6, on Plate XIII show the structure of
the region by a series of cross sections described in Mr.
D'lnvilliers' report on Centre county, T4, 1884, pp. 34
to 41. The rest appear as plates p. 668 &c. below.
The Madisonburg Gap cross-section, at the Clinton-
Centre county line, shows the Nittany axis barely a mile
distant from the Bald Eagle mountain in which the slates
of III are vertical or overturned (S. E. 80 to 86). Against
these rest the thin-bedded shaly Trenton limestones (He) ;
against these rest the white, hard crystalline, magnesian,
sandy Chazy limestones ; and under these on the arch the
limy sandstones of Sand ridge, making "The Barrens."
At the Washington Furnace and. Beck ore banks (2 m. N.
W. of the old Washington furnace) the measures are over-
turned, and the ore horizon is about 3000' beneath the Slates
of III. South of the arch the same ores lie at the Snavely,
Sallow and Day, and Huston banks, dipping 30, S. 85
E. (towards Nittany mountain) between beds of cherty lime-
stone (Chazy, or Calciferous) ; the slates of III at the base
of the mountain dipping 40, and the Medina sandstone
50, S. E.
* The Confer anticlinal only exposes III in Decker valley, and in the
small oval Lick valley (Lechenthal).
The Poe Valley anticlinal, passing from Union into Mifflin county, also
only exposes III along the north foot of Paddy's mountain and south foot
of Bald mountain.
24
370 GEOLOGICAL SURVEY OF PENNSYLVANIA.
The Howard and Jacksonville cross-section, 4 m. S. W.
of the last, shows the sand-lime strata (containing some
good pale blue beds) at Jacksonville overturned 68 to 80,
S. E. without any appearance of a break or fault in the
arch. Fossiliferous blue limestone quarries are N. W. of
the village ; and black shiny Utica slate, polished by slid-
ing pressure, within 300' of the Bald Eagle mountain, has
been prospected for coal ! Near the Butler ore bank inter-
stratified magnesian limestone and common sandstone
beds are overthrown to 50 or 60, S. E. Sand ridge has a
double, crest, the northern crest being made by very hard
blue flaggy sandstone beds; the southern covered with
loose sand. The sandstone beds are regularly inter strati-
fied with the magnesian limestone beds. The higher
southern ridge shows 20 to 25 dips to S. E. The ore hori-
zon in Madison Gap cross- section above here runs through
the Hecla, Voneda, and Schwartz mine limestones dipping
30 to 40, S. E. Then come the overlying dark blue Trenton
beds (He) making a reddish soil ; then the Utica black
slates, extensively prospected for coal, on the H. Brown
tract, dipping 40, S. E.
The Hecla Furnace cross- section, 3m. W. of last. In
Little Fishing Creek Gap IV dips 52, 40, 40, S. E. Be-
tween Nittany mountain and Sand ridge a shallow valley.
Blue very slightly calcareous sandstones, dipping 22, S. E.
were once quarried for paving flagstones (40, S. 30 E.)
near the McKinney ore bank. At the Darrah bank, N. W.
of the Sand ridge, the same blue silicious magnesian lime-
stones in bold ledges and cliffs dip 20 to 25, 8. E. into the
ridge.* Along the north road, magnesian limestones are
overturned to 85, 83, 70, 83, 80, 88 to S. E., but others
dip 85, 88, 60, 65, 76 normally N. W. The anticlinal
begins to get its normal shape after passing S. W. into
Spring township.
The Belief onte cross-section is the best that can be got
N. E. of the Little Juniata. The Barrens (sand ridge),
sinking 4m. E. of Belief onte, do not show the sandstones
*This is a mile from Bald Eagle mountain and must mean an excessive
overturn.
CROSS SECTIONS IN CENTRE COUNTY. 371
on the section. The Medina sandstones, IV, in Bald Eagle
mountain dip 80 to 70, N. W. The slates of III on the
mountain side, 50, N. W. The Trenton blue fossiliferous
limestones, IIIc, 600' thick, both massive and thin bedded,
fine grained and laminated, dip 50, N. W., as in the Alex-
ander and Morris quarries on Spring creek north of Belle-
fonte. Then at the Presbyterian church appear the upper-
most magnesian (Chazy) beds, banded, broken by cleavage
holding masses of chert, and decidedly whiter than those
above them ; all of them more or less sandy and cross-
cracked ; dipping on an average 50 (with local variations
of 30 to 60) N. W. to the anticlinal axis, a mile S. of
Bellefonte, were they only dip 9 N. W. and S. E. Then
the same beds descend in the same order, with S. E. dips of
30, 20, 12 and 10, toward Nittany mountain.
The Fillmore-Boalsburg cross-section, 6 miles further S.
W. crosses the whole valley ( m. W. of the end of Nit-
tany mountain) from the Bald Eagle mountain to Tussey
mountain, 8 miles, across the Nittany valley anticlinal, the
Nittany mountain synclinal, and the Brush Valley anticli-
nal. Here the bottom slates of III dip. 70, N. W. The
blue Trenton beds, at first 70, lower their dips so rapidly
that at Fillmore they dip only 20 to 15, N. W. Half a mile
further, on Crust farm, the arch of lime-sandstones is flat-
tened to 6 dips both ways (10, 12, well exposed on Spring
Creek, 1 m. S. of Roopsburg). South of the axis in Big
Hollow, N. W. of Houserville, purer limestones descend at
10, 15, 18, 16, 30, S. E. into Paddington ore banks. On
Slab Cabin run, 15, 20*, S. 60 E. (showing the shoaling of
the Nittany mountain synclinal). Here the long syncli-
nal prong of III is crossed. Then the Trenton limestones
rise steeply (50, 60, N. 20 W.). Then the lime sandstones
rise (48, N. W.) on the Brush Valley anticlinal, and sink
again (8 to 12, S. E. )covered by the Trenton beds descend-
ing at 20 to 30 under the slates of III in Tussey mountain.
372 GEOLOGICAL SURVEY OF PENNSYLVANIA.
CHAPTER XXXII.
Centre county limonite mines. Pennsylvania Furnace
ore banks.
Mr. E. V. d' Invilliers' elaborate report on Centre county,
T4, was published in 1884, when the iron industry of the
state was depressed, when only three of the four small char
coal furnaces were in blast and the supply of water for
washing the limonite ores of the county was very limited.
Since that date there has been an active movement in de-
veloping the iron ore resources of the district. Two large
coke furnaces, with the latest improvements, have been
erected at Belief on te by the Robert Valentine Company, and
the Philip Collins Company, and operated under various
changes of name. Brown hematite banks have been opened
up all along the ore belts, especially in the middle mem-
bers of the limestone series. Branch railroads have been
constructed to reach the mines near the State College and
along the foot of Bald Eagle mountain. The use of jigs to
separate the ore from the Hint and sandstone of the ore
masses is now common and will soon be universal. Water
for washing away the clay and sand is procured either from
the surface streams or, in the dry limestone districts, by
sinking artesian wells to the drainage level ; some of them
being several hundred feet deep, and at least one of them
west of the Huntingdon county line, a thousand feet.
The market for the ores is found at the numerous furnaces
along the main line of the Pennsylvania railroad and its
branches. The fuel used is coke from the Clear-field and
Connellsville coal districts.
Two varieties of ore. *
The two chief varieties of ore occurring in the county are :
1st. The wash and lump hematite ore of the " barrens." 2d.
The pipe ores.
*This paragraph and those that succeed it as far as to the end of the list of
mine groups are taken nearly verbatim from Mr. d'Invilliers' report on Cen-
tre county, T4, 1884, pp. 133 to 138. His detailed descriptions of the mines
of these groups occupy 117 pages of that volume (pp. 139 to 256) of which no
summary can be made with any success. I will confine myself to a de-
scription of the great Pennsylvania furnace mine and refer the reader for
the rest to his excellent work.
CENTRE COUNTY LIMONITE MINES. 373
1. Of the first class it may be stated that the appearance
and character of the ore in all the banks, as well as the ac-
companying waste material, show evidence of their being
waste deposits, caught in vast caverns of irregular shape,
showing mixed sand, tough clay and rolled ore, and though
intimately associated with sandy measures in the limestone
formation of II have really a still lower limestone bottom.
In the chief mines of the district notably at Scotia and
Tow hill after a superficial covering of 15 to 30 feet of
mixed clay, sand and fine ore has been removed, the under
surface reveals solid rock-ore in large lumps, mixed with
clay in a confused arrangement, of great richness and va-
riety. An integral difference in the clays of these ores and
the limestone pipe ores (one to be expected probably from
their different horizons) is the much greater stiffness and
toughness of the former. The clay of these lower ores fre-
quently occurs in non-ferruginous bands or dykes, running
through the length of the banks, barren, and hard .to pass
through the washers, but by no means cutting off the ore.
This non-ferruginous clay has usually a white to pink
color ; while the yellow clay of the pipe ore deposits is inti-
mately mixed with the ores and offers no material resistence
to their thorough cleansing in the washing-machines.
Moreover, it may be noted that in every case the ore of
the barren needs jigging in addition to washing to free it
from the mixed sand and flint that accompany it.
All the analyses of these ores show an absence of bisul-
phide of iron, and the occurrence of all the iron as sesqui-
oxide at once suggested a different chain of effects in the
production of these as compared with the pipe ores, to be
presently described, where this salt of iron is frequently
present.
The sand rocks which originally held these ores occupy
a position low down in the sandlime series of II. By
having their lime leached out, these loosely aggregated
sandstones have fallen into sand, and it is probable that
this same leaching action has concentrated their iron salts,
which would be deposited as insoluble peroxide. What
changes may have followed this process of deposition to
374 GEOLOGICAL SURVEY OF PENNSYLVANIA.
bring about the irregular and confused appearance of the
banks to-day and the grading of the ore body from fine to
coarse lumps is a matter of speculation still. The deposits
do not look like formations in situ, nor would such a theory
explain the rounded character of ore and flint balls and
occurrence of barren spots beside nests of great richness.
While no distinctively pipe ores have been reported from
the ore banks in the "barrens," some persons detect in the
compact needle ore (occasionally met with) a form of pipe,
and illustrate their opinions of the common origin of pipe
and hematite ores by this fact. Physically and chemically
they appear to be quite different ; but the general resem-
blance of all ores from different banks, divided only as to
two classes, is not as remarkable as the local variations
which give rise to the occurrence of bessemer, neutral and
cold-short ores lying quite close to each other, and appar-
ently along the same range.
2. The pipe ores have varying horizons in the limestone,
and though generally above the essential ''barrens" limo-
nites, it is by no means certain that some of them do not
occur also in the 1000 feet of limestone beneath these.
The frequent connection of damourite slate beds with the
chief ore bodies in the southeastern district of the State is
not observed in Centre county. It is true that most of the
pipe ores are accompanied with a white and buff-colored clay,
which may be the result of the decomposition of such slate
bands ; but it may also represent the disintegration of the
magnesian limestones themselves.
While the chemical explanation of these facts is still a
matter of speculation, repeated examinations of the ore
banks in various parts of Nittany and Penns valleys leads
me to believe that the pipe ores are deposits probably due
either, first: To the decomposition of iron pyrites, origi-
nally contained in the limestone or slate bands, and after
oxidation as sulphate, filled into interstices in the limestone,
and changed into peroxide by contact with vegetable mat-
ter or other organic substances ; or, second : To the prior pro-
duction of ferrous carbonate, by reaction between the fer-
rous sulphate and the calcium carbonate of the limestone,
CENTRE COUNTY LIMONITE MINES. 375
afterwards converted into limonite by oxidation and hydra-
tion. The manner of occurrence between walls of regularly-
bedded limestone, sometimes as thin shells of ore and again
as large pipes in masses 8 to 10 feet thick, would confirm
one or the other of these views, while the presence of iron
pyrites in perfectly undecomposed pipes surrounded with
thoroughly oxidized ore in the Sinking Creek mine in Penns
valley, lends probability to the theory. The presence of
pyrites in hematite is not new, and the many analyses show-
ing bi-sulphide of iron in the succeeding pages will illus-
trate its frequency in this district. Crystallized brown
hematite, a pseudomorph after pyrite, has been gathered
in the Cumberland valley, as well as specimens of bombr
shell ore holding a clay inside filled with loose crystals
of pyrites.
In other banks showing a low percentage of sulphur
many of these ores may have occurred as carbonates in the
slates, which upon the dissolution of their lime matter
have deposited these iron salts as now found. In those
banks where a considerable surface deposit has escaped
from the general erosion, this oxidation has been so com*-
plete as to show but a low percentage of sulphur ; whereas,
in the case of the Sinking Creek mine before mentioned,
the ore occurs in places between limestone beds, and has not
yet had a chance to become thoroughly changed.
The outcropping of these pipe ores is spread out to a
much greater extent than they occupy lower down be-
tween limestone layers. The width of these outcrops is
affected by the topography of the country. This surface
ore is greatly disintegrated, and occasionally is indeed so
fine as to be hardly distinguished from so much reddish
brown loam or earth ; but a close inspection of it will re-
veal the presence of small stems or pipes, making usually
a cubic yard of ore for each 4 or 5 cubic yards of material,
and often better.
The work of the season did not confirm the popular be-
lief in continuous belts of ore-producing territory along
miles of surface outcrop. At best, while assigning approx-
imate horizons to these pipe ore deposits, they have their
376 GEOLOGICAL SURVEY OF PENNSYLVANIA.
Section ofPenn's Valley through BoaLsburg.
/. XIV.
Section through the Henderson farm S.W.ofBoalsburcj.
* ,
Map ffftfie <Pe7JiiAylrania andaderlimoitifc /a/net;,, Centre Co:
CENTRE COUNTY LIMONITE MINES.
377
JVate XV.
ci limonite mine in 6enf/re Go. &CL.
378 GEOLOGICAL SURVEY OF PENNSYLVANIA.
rich and poor places feather out entirely in the line of
strike and widen again into masses several yards thick,
while keeping a general parallelism of bedding with the
parent rock and liable to show its change of dip. It is use-
less to speculate on the possibilities of these deposits, but
the ore has been found at great depths, and much original
outcrop soil is as yet untouched. For convenience sake it
has been thought best to describe them in groups geogra-
phical rather than geological, as follows :
Belief onle-Nitlany Valley group, embracing the follow-
ing banks : Curtm Bros., Fishing Creek bank, Jackson
mine, Red bank, Hoy bank, etc., Gatesburg, Taylor, Nigh,
and Logan banks.
Jacksonville Valley group, containing Zimmerman,
Darrah, McCalmont, Butler, Beck and Washington Fur-
nace bank, etc.
Hublersburg Valley group, with the Field, McKinney
Quinn, Hecla, Howard, Voneda, Schwartz, Huston 1 and 2,
Snavely and Barlow & Day mines.
Buffalo Run group, Hunter, Crust, Markle, Lambourn,
Pond, Newell, Desert and Celtic banks.
Barrens group, Lovetown, Tow Hill, Scotia, Ackley,
Lytle, Red bank, Bull bank, etc.
Pennsylvania Furnace and College group, holding Bry-
son bank, Johnson, Streuble, Stover, Puddington, and Big
Hollow banks.
Perm's Valley group, Watson, Ross, Sinking Creek, J.
P. Rankle, Emerick, etc.
The Pennsylvania Furnace mine.
This famous ore bank, on Spruce creek, in Centre county,
close to the Huntingdon county line, has been mined since
1815. Its situation in respect to the other ore mines of Nit-
tany Valley is shown on local map, Plate XIV, page 376,
Fig. 2.* A special map of the mine as it was in 1873 is on
*T4, 1884, Appendix A, p. 372. Extracts from J. P. Lesley's report to
Lyon, Shorb & Co., in 1873. All figures given in the text above are copied
(reduced to I linear) of. the figures in T4. They will serve well enough as
illustrations.
PENNSYLVANIA FURNACE MINE. 379
the same plate, Fig. 3. On Plate XV, page 377, Fig 1 is
a view of the mine from the top of its S. W. wall ; Fig. 2 is
a near view of the ribs of undecomposed rock in the pro-
montory seen at the edge of Fig. 1 ; and Fig. 3 shows the
height of the wash ore in the walls.
The great excavation is aboat 1400' long by 600' wide and
60' deep, but shafts sunk 35' to a permanent water level
proved that other and even better ore masses lie at least that
much deeper, and these are covered by undecomposed
lime rocks dipping 40, S. E. as seen in the walls of the
promontory above.
The geologist can here study the theory of the formation
of the Lower Silurian brown hematite ores of Pennsylva-
nia to great advantage. I know no better place, and few
so good.
The ores are evidently not washings from a distance ;
neither from Tussey mountain, nor from the present sur-
face of the anticlinal ridge ; nor from any formerly existing
surface in past geological ages, when the surface stood at
a much higher elevation above sea level. They are evi-
dently and visibly interstratih'ed with the soft clay and
solid limestone layers, and obey the strike and dip of the
country ; the strike being along the valley, and the dip
about 40 towards the southeast.
Thousands of minor irregularities prevail ; the streaks of
ore and masses of clay are wrinkled and bunched, and thin
out and thicken again in various directions. But all this
irregularity is owing to the chemical changes of the strata,
and to the changes in bulk of the different layers during
the protracted process of solution and dissolution, during
which the looser calciferous and ferriferous sandstone lay-
ers have lost their lime constituent, packed their sand and
clay more solidly, and perhydrated their iron. In this long
process cleavage planes have been widened into crevices ;
caverns have been excavated; pools or vats have been cre-
ated ; precipitates of massive (rock and pipe) ore have been
thrown down; and a general creeping and wrinkling of the
country been effected. But the original general arrange-
ment or stratification has been preserved ; and those por-
380 GEOLOGICAL SURVEY OF PENNSYLVANIA.
tions of the whole formation which had but little lime
have been left standing as sandstone strata ; while others
having but little sand remain as solid and massive lime-
stone strata; those which had an excess of alumina are now
in the condition of streaks, masses, or layers of white or
mottled clays ; and only such as were properly constituted
clay-sand-lime-iron deposits (originally) have been so com-
pletely dissolved as to permit the lime to flow off, and the
iron to consolidate into ore.
Every stage of this interesting operation, and every phase
which it presents in other parts of the Appalachian belt of
the United States from Canada to Alabama may be seen
and studied in these old and extensive ore banks of Penn-
sylvania furnace.
At first sight of the bank the ore deposit looks as if it
were a grand wash or swash of mingled clay and fine and
coarse ore grains and balls, occupying hollows, caverns and
crevices in the surface of the earth and between the solid
limestone rocks; and some of it undoubtedly has been thus
carried down into the enlarged cleavage partings of the
limestones ; and into sinkholes and caverns formed by
water-courses ; where it now lies (or lay when excavated)
banked up against walls or faces of the undecomposed lime
rock. But as a whole the ore streaks and "main vein" of
ore must occupy nearly the places originally occupied by
the more ferruginous strata after they had got their dip and
strike.
The ore is taken out with the clay, and hauled up an in-
cline by means of a stationary steam engine at its head, and
dumped into a large washing machine, with revolving
screens ; whence, after the flints and sandstones have been
picked out, it is carried on an ironed tramway to the bridge
house of the furnace.
The ore forms from 10 to 50 per cent, of the mass exca-
vated, and the small amount of handling makes the ore
cheap.
The upper ores will furnish stock for yet many years.
After that, or in case more furnaces are erected, or distant
markets calls for the shipment of ore by railway, deep shafts
PENNSYLVANIA FURNACE MINE. 381
or bore holes must be sunk to drain the underground, and
the lower ones may then be lifted to an unknown extent.
The prism of ore in siglit in 1873, calculated roughly from
the old banks and new cuts and shafts, old and new, in
various places, contains several millions of tons of wash
ore, lump ore, and pipe (rock) ore.* But the unproven ore
ground ranges far into the surrounding lands. A large
new area was stripped in 1873. Large quantities of ore are
left between the limestone ribs in the walls of the pit, as
shown in Figs. 33, 34. The limestone ribs dip 35 to 40, S,
35 E. on the range of natural outcrops shown in the local
map, Fig. 37. Slight crumplings of the limestone vary the
dip from 18 to 65 ; but these are due either to movements
in the yielding ore mass or to a deception caused by mis-
taking cleavage planes for bed plates. No such variations
are apparent at a distance from the banks, the whole
limestone formation descending uniformly beneath the
foot of Tussey mountain with a dip of something under 40.
The height of the walls of the various excavations may
be seen by reference to the ten-foot contour lines in Fig, 37.
These also show that the ground now so deeply excavated
once formed a high divide between a vale descending south-
west to Spruce Creek, and a corresponding but shallower
vale descending northeast to the settling-dam hollow. It
looks as if the ore once lilled both these vales, but has been
swept away by the natural drainage into Spruce Creek,
from the one which descends in that direction, and, perhaps,
from the valley of Spruce Creek itself, down to and beyond
the- Furnace.
The entire walls of the cuts are of wash ore, and it is
all torn down and taken to the washing machine. But
the tops of pyramids of solid pipe ore are exposed in the
floor, and some reached to, or nearly to, the sod above.
At one of the deepest places in the floor, 60 feet below the
sod a shaft was sunk 40 feet further through solid pipe
* Proved area 550 x450 yards, which at 15 yards depth gives 3^ millions of
cubic yards, affording 600,000 tons of washed ore ready for use. Of this 100,-
000 have been smelted into 50,000 tons of neutral cold blast charcoal iron of
the best quality.
382 GEOLOGICAL SURVEY OF PENNSYLVANIA.
ore, and then limestone, and was stopped by water. Water
does not stand in the present floors on account of the free
circulation at a still lower depth through crevices and cav-
erns communicating with Spruce Creek, which itself issues
from a cave.
The original name of the Pennsylvania ore bank was the
Bryson cut. It was examined again by Mr. d'Invilliers in
1883, who found it little changed since my study of it in
1873. At that time (1883) it was in common with most of
our mines idle, but a new lease promised afresh develop-
ment of it under better auspices.
The HosJcer bank is on the steep N. W. dips of the Gale
Hollow anticlinal ridge, so low down in II as to be 2500'
beneath III. The Pennsylvania ore rocks on the S. E. side
of the ridge and dipping 40 S. E. are also sandy dolomites ;
but above them lies a series of white and blue limestones ;
and above all lie soft, blue and dove colored Trenton lime-
stones dipping 18 or 15, S. E. under the slates of III.
The Bryson cut ores are essentially pipe, finely disinte-
grated, and occurring in every conceivable form, whether
in streaks of ore and clay, or in flattened scales, or bunched
with sandy limestone, or in solid pipe masses ; but every-
where showing a tendency to interstratitication and point-
ing to their probable formation in place by the dissolution
and leaching of the limestone rocks and the filling in of
cavities with mixed sand, clay and iron-ore. Comparatively
little lime has been left in this ore, showing how thorough
dissolution has been ; and the percentage of magnesia,
though low, is probably due to its less solubility as com-
pared with the corresponding lime salt.
Very little of the quartz and flint grains found with the
ore are water-worn or rounded, and so create at once a
marked difference between these ores and those of the bar-
rens in the Scotia- Juniata range. But it must be remem-
bered that these latter ores are much lower down in the
measures. When visited in July, 1883, no work had been
done here since the fall of 1882, when Carnegie Bros. & Co.
returned their lease of the property.
The Messrs. Carnegie, while doing some little mining in
PENNSYLVANIA FURNACE MINE. 383
the old workings south of the washer, turned most of their
attention to the development of the New bank located east
of the former and shown on map. About 10 acres in all
have been disturbed here.
Various estimates have been made by different parties of
the original amount of ore contained in this deposit (which
roughly measured may be taken a t 500 yards N. W. and S.
E. and 350 yards N. E. and S. W.) which vary from 200,-
000 tons up to 600,000 tons, with a possible output of even
1,000,000 tons, allowing for increased depths over 50 feet,
etc. All such estimates are greatly affected by the frequent
occurrence of limestone ledges, clay banks and lean faces,
and are in every case when carried beyond the depth of the
wash deposit and into the solid pipes in the bottom, merely
speculative.
The average wash of the materials is about 1 to 8 or 9,
which will give 1 ton of ore to each 6 or 7 cubic yards of
material, a cubic yard of ore being estimated to weigh only
1J tons. The washers occasionally showed a record of one
to five, but this was when mining was being carried on in ex-
ceptional ground. The majority of the more recent pits
(some outside the limits above given) show a depth of only
abou 1 10' of wash ore, under which clay and limestone occur.
The old charcoal furnace was changed in 1881 to a coke
furnace of 11' at bosh, 43' high and 8' at tunnel head. It
was not successful. The incline plane was abandoned and a
narrow gauge railway running down around the edges of
the pit was substituted. The new washers had a capacity
of 140 tons daily for good rich ore. The difficulty was to
separate the light pipe ore from the heavy flint ; also to-
keep the flat or scaly ore from floating off the rig. Boys
had to pick out the flints. A steam excavator was tried for
stoping down the walls but failed on account of project-
ing noses or ribs of limestone.
The deepest part of the old bank has been nearly ex-
hausted of cheap ore, and show several outcrops of silicious
sandy dolomite, very much broken, but dipping southeast.
This rock is frequently ore-bearing, showing occasionally
streaks from one-sixteenth to several inches thick. While
384 GEOLOGICAL SURVEY OF PENNSYLVANIA.
occurring in the center of the deposit, they do not seem to
have affected the ore which occurs above and below them
and frequently interstratified with them. Some 30 to 60
feet of stripping has been done here, but shafts sunk from
the bottom of the open cut 30 to 40 feet deeper have proved
the presence of good ore ground as yet untouched. In the
days of early mining here tine exposures of pipes 40' high
are reported, though none such are to be seen to-day.
The best ground, when last visited, seemed to be along the
south side of the new workings, where really excellent
wash ore still remained untouched in a face 30' high. Good
lump ore is reported all along the bottom of these workings,
now covered with tine silt and mud, and in any future work
this should be mined with the wash surface ore or that in
the east end, thus making a cheap and rich average ore.
All the work so far has been done above ground, the floor
being usually limestone.
Dr. Genth's analyses of (1) two samples of amorphous,
brown compact ore mixed with ochreous yellowish or red-
dish ore, some of its cavities lined with very fine coating of
fibrous ore, and (2) of pipe ore, with cavities filled with fea-
ruginous clay, were Fer. ox., 81.55 (83.74) ; mang. ox.,
0.10 (0.31) ; cobaltic ox., a trace (a trace) ; alumina, 1.49
(0.33) ; magnesia, 0.47(0.34) ; lime, a trace (a trace) ; phos.
acid, 0.16 (0.14) ; sil. acid, 2.98 (2.57) ; quartz, 1.55 (0.44) ;
water, 11. 70 (12. 13) ; thatis7r<w, 57.10(58.62) ; Phosphorus,
0.07 (0.06) ; or phosphorus in 100 parts iron, 0.12 (0.10).
Dr. Genth's analysis of the sand rock ribs was: Ferr.
ox., 43.65 ; mang. and cob. ox., 1.55 ; al., 2.43 ; mag., 1.64
lime. 0.12 ; phos. acid. 0.27 ; sil. acid, 5.19 ; quartz, 36.52 ;
water, 8.63. It contained, therefore, 30 per cent, of iron.*
* " The above analyses show besides the mechanically admixed rounded
grains of sand, which I distinguish as 'quartz', a considerable quantity of
silicic acid, which is in chemical combination, probably as a hydrous ferric
oxide. But as it is impossible to say what the true character of this min-
eral may be, whether authosiderate, or degeroaite a silicate of the composi-
tion Fe 2 O 3 , 2SiO 2 -j-3H 2 O or a species not yet known in its pure state, suffice
it to say that all these ores are mechanical mixtures of limonite with hy-
drous ferric silicate and minute quantities of hydrous ferric phosphates,
perhaps dufrenite or cacoxenite ; some of the ores contain beside these,
PENNSYLVANIA FURNACE MINE. 385
Dr. Genth recognizes three varieties of limestone in this
bank, and the results of his analyses are as follows :
No. 1. Upper limestone, dark gray, compact, slightly
crystalline. The atomic ratio between the magnesia and
lime is 1 : 15.
No. 2. Pale ash .gray, very finely crystalline, rough to
the touch like rotten stone, very friable and easily falling
to powder, a true dolomite. Atomic ratio between mag-
nesia and lime, 1 : 1.
No. 3. Yellowish gray, soft, rotten, feels rough to the
touch, sandy ; crystalline ; has a laminated structure ;
also a dolomite. Atomic ratio between magnesia and lime,
1:1.08.*
small quantities of manganese ores, mostly the so-called ' bog-manganese'
or wad, but also pyrolusite and Psilomelane.
"It is a very remarkable fact that, although these iron ores are, to a great
extent at least, the result of the decomposition of limestones and by them
precipitated, that almost the entire amount of lime has been washed out of
them and only traces are remaining ; of the second constituent of the lime-
stones, the magnesia, a somewhat larger quantity is left behind, owing un-
doubtedly to the lesser solubility of its carbonate in carbonic acid water."
(Dr. F. A. Gen., T3, p. 434.)
* Dr. Genth's analysis of a 4' bed of limestone capping 33' of pipe ore in the
Hostler bank (T3, p. 435) shows that it too is a true dolomite, but holding
4.33 of quartz and silicic acid. He adds (p. 436) : " It is remarkable that
the limestones and dolomites, of which I give the analyses, contain almost
the entire amount of silicic acid as quartz ; only a small quantity is present
as soluble silicic acid and in combination with alumina. If the limestones
and dolomites are dissolved in acid, the quartz remains often as a scoriaceous
mass or in irregular sandy but not rounded or water-worn grains ; some-
times it forms large coherent slaty masses in the limestone, frequently filled
with minute cavities, previously occupied by rhombohedral crystals of dol-
omite. Similar pieces found in the Pennsylvania bank are white like por-
celain and show the same cavities of rhombohedral crystals. Other varieties
of limestone in the Pennsylvania bank have a still greater admixture of
quartz and are a real calciferous sand rock."
(1) (2) (3)
Carbonate of iron, 1.31 0.45 .118
" " manganese, 0.18 0.06 trace.
" " magnesia, 3.98 42.39 35.51
lime, 72.67 51.25 45.73
Quartz and silicic acid, 18.05 5.03 15.83
Alumina, 3.81 0.82 1.75
Total, 100.00 100.00 1QQ.OQ
Metallic iron, 0.63 ~ 0.22 0.57
Magnesia, 1.90 20.19 16.91
Lime, 40.69 28.70 25.61
25
386 GEOLOGICAL SURVEY OF PENNSYLVANIA
Dr. Henderson before his death sent me a cross-section,
which he had made on his own farm 4m. N. E. of the
Pennsylvania bank, see Fig. 1, plate XIV. By his calcula-
tion the Pennsylvania ore horizon lies 2200' beneath No.
Ill, with another ore horizon 300' above it, and a third one
800' above it ; that is, only 1400' beneath No. III.
NITTANY VALLEY, HUNTINGDON CO. ORE MINKS 887
CHAPTER XXXIII.
Nittany valley, Huntingdon county ore mines.
Before describing the banks I must continue the struct-
ure of Nittany valley through Huntingdon county to the
little Juniata river. A few words and the accompanying
cross-sections on plate XI Y will suffice.*
If my cross-section along Warrior's Run (T3, Fig. 3) be
correctly drawn it exhibits four ore horizons rising to the
surface, one after the other, from S. E. to N. W., their out-
cropping rocks making parallel belts of ore banks, and their
respective depths geologically beneath the bottom of for-
mation III being as follows :
Trenton limestone, etc., etc.
Pennsylvania and Gale Hollow banks, 2500'
Barren interval, 700'.
Huntingdon furnace ore banks, 3WO'
Barren interval, 550'.
Tollgate pipe ore range, 3750'
Barren interval, 1500'.
Pennington, Town, Loveiown banks, 5250'
*The cross-sections in T3, Figs. 1, 2, 3, pp.376, 378, 380, embody my views
of the structure after my private survey of the legion for Lyon, Shorb &Co.
in 1872. I was assisted in a contour line survey of it by Mr. Franklin Platt,
from whose field notes the contoured map was plotted and drawn and the
ore banks located. In 1882, during the progress of the state survey, my
topographical assistants, Mr. E. B. Harden and Mr. O. B. Harden, surveyed
and mapped that most troubled and obscure part of the valley lying east of
Tyrone forges and Birmingham to get the faults in Bald Eagle mountain,
and the true location and character of the Nittany axis in Pennington ridge.
The following year Mr. d'Invilliers went over the ground in furtherance of
his own work in Centre county ; and his criticisms on my sections of 1872
will be found in the report on Huntingdon county, T3, pp. 443 to 445, his
chief objection being to my little Logan creek synclinal, as he would prefer
to consider the S. E. dips along Logan creek as overturned N. W. dips. Nor
am I at all positive that my original construction of the rise of the limestone
mass over the Bald Eagle mountain at the Tyrone gap is the correct one,
although my observations along Logan creek were long, close and carefully
studied, and my section was drawn in full view of the fact that a downward
brush of the edges of the limestones against the opposite (N. W.) side of the
fault was rather to be expected.
388 GEOLOGICAL SURVEY OF PENNSYLVANIA.
Cratt faction^ in
Ti. xvr
Co.
NITTANY VALLEY ORE BANKS.
Jftttany "VaUey.
topographical sketch, ntcyy in&O'contours made in 1873
locating the Ore t&anks &f zHountingctcn aTitf Centre GPJ
Jieldurork 6y FWcttb.
GEOLOGICAL SURVEY OF PENNSYLVANIA.
Pennington range in Huntingdon County.
The lowest range of ore banks is described in T3, p. 388 ;
and pi. XIV, f. 8, gives their arrangement.* It commences
2 m. from the Jtiniata and runs 2 miles to the RR. 1 m. W.
of Warrior Mark village ; the N. W. face of the ridge
covered with wash ore, underneath which lie sheets, belts,
and masses of rock ore between ribs of undissohed lime-
sand rock, with inter stratified beds of lime-shales turned
into white clay.-\
That rich ore masses descend N. W. in a series of ir-
regular but continuous floors and layers between the clay
beds was proved by the gallery work driven in wavy ore.
Great quantities of salable ore and wash ore also existed.:}:
The main open cut 700'xlOO'xl5' to 25' deep has wash ore
walls, 15'. A shaft struck (at 15') manganese ore 5'. In this
pit stands a solid rib of half decomposed limy-sandstone
strata, carrying more or less ore, dipping gently N. W. ;
bunches of good ore in ferruginous sandstone. It is an
admirable place to study the genesis of our limonite ores.
The West Pennington bank (Fig. 10), m. from the last,
550'xl20' is wholly in wash ore ; yielded richly for 7 years
as an open cut to a depth of 40'; then worked by galleries
(Fig. 12). Another open cut 200' further west, 300'x45'x 25'
deep (once much deeper) in wash ore. Another, 400' fur-
* The Pennington ridge anticlinal loses itself in the hill N. of Warrior
Mark village and in the great fault further on. Obscure dips of 80, N. W.
in limy sandstone 500 yards N. W. of the village, might very well be mis-
taken for 30 to 60 S. E. dips on account of the innumerable cleavage
planes ; but 80, N. W. dips are seen in blue limestone 450 yards further
up Warrior Run. All the outcrops N. E. of Warrior Mark village belong
to the S. E. side of the Pennington ridge anticlinal, as any one can see who
travels along the road to Lovetown. Therefore the Pennington ore range
is a short one ; but the next ore range to the S. E. of it runs on through
Warrior Mark village and Lovetown into Centre county.
f Fig. 9 is a reduced copy of Booking's map of the underground tunnel
workings, shafts, etc., in the Old or East bank. Water stopped most of the
old mining. One old shaft 30' deep was deepened to 60' and struck the
sandstone floor. Another shaft in 1865 reached the ore bottom at 45. For
further details see T3, p. 392.
{Thus the first pit near the RR. 200'x50'xl5 deep yielded 5000 cubic yards
of wash ore without solid lump. Shaft No. 1 near it went through top wash
15', rich lump 5', barren clay 25', good lump 15'. Shaft No. 2, lean ore on
top, clay to 40', good lump 10'.
NITTANY VALLEY ORE BANKS. 391
ther west (Old Phillips' bank), 300'x90'x20'; once deeper
and drained by a tunnel. 420' long.* The Beck bank, % m. N.
E. of old Pennington bank, is 120'x60'xl5' deep. The New
Town bank (also Beck' s], 1 m. further N. E., stopped by
water, ore in floor.
Warrior Mark and Lovetown range.
From Warrior run, N. E., we have almost a continuous
series of shafts and open cuts on thes ame lowest lime-
sand horizon as the Pennington, but on the S. E. dip ;
thus
Old Town (i m. E. of Warrior run) ; Romberger' s (1) ;
Hannah (If) ; Waiters (2i) ; Braunstetter' s (2f) with pipe
ore outcrops to the S. E. of it ; Disputed (4f ) ; Hannah
furnace (5) ; Hannah furnace and Beck ( m. N. of the
last two, and less than a mile W. of Lovetown) ; Pipe ore
pits (^m. S. of Lovetown) ; 8aw mill ore crops (2 m. N. E.
of Lovetown) ; Hannah furnace and Bryan (2f ) ; Curtin
(5).f
The ores, when rich, are black or very dark, much of it
pitchy lustrous, often inclining to cold shortness;:}: the
leaner ore of a lighter brown ; clay predominating over sand
in the deposits ; perhaps some of them somewhat higher in
II than the Pennington, but still very low in the formation.
Dry Hollow range in Huntingdon County.
Under this head in T3, pp. 404 are described, figured and
mapped: Pond bank No. 2; Wryebank; Old Sandy;
*This range, with its lean layers and sand masses so low in II (Cal. SS.),
"holds purplish, easy smelting ore, mixed with day and without discerni-
ble regular veins" (Booking) . Plenty of wash ore ; but dry screening im-
possible. It is evident that a vast quantity of ore is still to be won, but it
can only be won by scientific stoping and washing. The extensive dry
tailings covering the slope north of the cuts can be profitably washed and
got out of the way of deep mining (J. W. Harden). When powerful pump-
ing machinery is employed many hundred thousand tons will be won at a
market profit
t Their descriptions, with local map figures, can be found in my report
embodied in report T3, pp. 400 to 404. The description of the Lovetown
banks will be found in T4, pp. 354 to 360, with local map Figs. 20 to 25.
} See Dr. F. A. Genth's analyses in T3, pp. 427, 429.
392 GEOLOGICAL SURVEY OF PENNSYLVANIA.
Tl. XV//I
JVittany Yalley Unwnjh ore lanfa . 1873.
NITTANY VALLEY ORE BANKS.
393
1 XJX.
y Tafley ore banks inffiuntinydon Co.
394 GEOLOGICAL SURVEY OF PENNSYLVANIA.
Simpson's; Dixort s ; Litlle Dry Hollow ; Dry Hollow;
Old Red bank; Bean bank ; Bressler's*
The great breadth of the Dry Hollow belt is sufficient
evidence that it covers more than one geological horizon ;
and to this is added another proof, the different character
of the ore in (for example) the Pond and Wrye banks. It
is quite certain that the banks of this group or belt are in
geological range with the Kerr and Bredin, Hosker, and
Pennsylvania Furnace banks.
Cale Hollow range in Huntingdon county.
This is separated from the Dry Hollow range by Hickory
ridge and its ores lie in a deeper and narrower trough, but
at the outcrops of the same rocks, therefore of the same
horizon, and of the same character, except that an abun-
dance of pipe ore has been mined from Cale Hollow and
very little from Dry Hollow.
The banks of this range described in T3, p. 413, are the
Kerr and Bredin bank, of high reputation for its "gun
* I can only extract a few sentences of most note, and refer the reader to
the reports. In the Wrye bank an old miner said they went through worth-
less wash ore 26' and then 18' good lump ore, and still in the floor, What
the charcoal furnace men called worthless is now valuable to hot blast coke
and anthracite furnace men. It is also reported that the top of the ore
mass at one place sank to 50', thinned away and rose again. Rich solid ore
still stands 45' beneath the surface. In Jos. Kreider's fields the surface
show indicates a heavy mass of rich solid ore underground. The Dry Hol-
low pits occupy a great space and have had formerly a great output ; mostly
of fine wash ore in clay ; shafts going down 60' through wash and lump
ore, and always drowned out for want of adequate pumping power; only
the lump ore marketed, the small wash ore despised. The connection of
Dry Hollow with Red Bank solid ore ground under the surface wash is cer-
tain. The RR. cut exposes wash ore for 300' or 400', in some places 10'
thick resting on clay, in other places 20' or 25' thick holding large lumps of
solid ore. The varying thickness of the red clay and ore layers in these ex-
posures teaches the meaning to be drawn from the miners' trial shafts.
Some of the solid lumps weigh 300 or 400 Ibs. Very few chert fragments are
seen ; in fact this exposure shows less silica than any other in the valley.
Little or no soil covering exists. At Bean bank the surface ore lumps were
lifted and sent to Huntingdon furnace ; and it is the practice elsewhere ; no
attention paid to the great body of wash ore ; no effort to mine to the deep;
consequently a vast amount of ore ground awaits future exploration and
excavation, even within a mile of the railroad. (T3, 412.)
NITTANY VALLEY ORE BANKS. 395
metal ore," much resembling that of the Bloomtield banks
in Morrison's cove, Blair county.*
The wash ore ground continues along Hickory ridge.
Bronsteiter 's pits are 1 ni. W. To the east it continues
to Little bank in Half Moon run, with dips of 20, &c., S.
30 E.
The Hostler bank on the N. W. slope of the Spruce
Creek anticlinal, 2 m. S. W. of Pennsylvania furnace which
used the ore ; a large open cut in "pipe" wash ore (some-
times mixed with lump) 60' and 65' deep, in all the shafts ;
one of which struck (at 65') solid limerock 10" to 2' thick ;
below which pipe ore 45' deep.
It is a constant and important feature of the pipe ore
banks of the southeastern ore range, that they do not
exhibit the so-called lean ores of the lower geological
horizons in the ore ranges to the N. W. of it, in the
Barrens, &c. It has been the uniform experience at the
Hostler, Pennsylvania and other pipe ore banks that shafts
and borings have always passed through lump ore after
having been sunk or drilled below water level ; but never
reached its bottom because they could not be kept clear
of water owing to deficient pumping power. The under-
ground drainage all through the valley is immensely co-
pious, and the largest, deepest bodies of heavy ore are yet
to be won by better mining. f
Red bank, and several old pits, lead on N. E. to Little
bank, If m. W. of Penn furnace. Eyef 's bank is a mile
further on on the E. side of Half Moon run. Then (across
* Analysis by Dr. Ge'nth: Ferric oxide, 70.67 (as compared with Dr.
Wuth's analysis of Bloomfield ore, 78.63); man g. ox., 0.36 (mang. 0.29);
cobaltic ox. a trace ; alumina 3.91 (2.50); magnesia, 0.26 (0.38); lime, a trace
(0.34); phos. acid, 0.19 (0.134); sil. acid, 5.48 (7.02) ; quartz, 680; water, 12.33
(10.71). The extra quartz in Dr. Genth's analysis lowers the p. c. of iron to
49.47, as compared with Dr. Wuth's 55.04 (T3, 413).
|T3, 417, quoting J. P. L. in report of 1872. Mr. Booking writes that 35'
ore will pay well for stripping 65' to 75' of overclays. The Hostler pits
measure 360'xl50'x30'. The ore lies in clays separating ribs of undecomposed
limestone. The clays are mouldered lime shale partings between solid lime-
stones. Shafts more recently sunk went through alternate ore clays and
limestone ribs, dipping 38 N. 35 W. In the N. W. shaft 75' wash ore lay
on the first solid limestone. The wide flat part of Cale Hollow was 20 years
ago after many years of "ground-hog mining" still a virgin district.
396 GEOLOGICAL SURVEY OF PENNSYLVANIA.
NITTANY VALLEY ORE BANKS.
397
398 GEOLOGICAL SURVEY OF PENNSYLVANIA.
a divide) the ore follows Tadpole run in Sleepy Hollow at
the head of the Beaver dams ; then the dry hollow beyond
is a repetition of Gale Hollow ; and so the outcrops con-
tinue to McAllister's and School House cross roads, 8 miles
from the Hostler bank.*
The pipe ore horizons have a geological range of at least
1250'. This is conclusively proved by a careful section of
exposures along Warrior Mark run above and below the
Old Seat bank, ty m. S. E. of the RR. bridge over the run. f
Huntingdon furna ce banks.
Within a circle of two miles radius around the furnace,
among 10 S. E. dipping rocks, are the Wilson bank ;\ the
Keefer banks ; the Dorsey banks ; whole length of ore
ground, 6000' ; maximum breadth, 1500' ; in prolongation
of the Dry Hollow range before described, and in all re-
spects for mining purposes, resembling it. Much lean ore
is mingled with the rich, and much dead stripping is re-
quired ; but the liver colored, sandier ore lies on the N.
W. side of the belt, up the hill side, lower in geological
* Beyond this, towards Pine Grove mills, the old Weaver banks are not
regular pipe ores, but the liver colored red short ores of lower horizons
brought to the surface of the broad plateau by the Brush Valley anticlinal
(T3, 420).
f See full description T3, 422. Beginning at the mouth of Gale Hollow, 1 m.
E. of Huntingdon furnace, an old pipe ore bank shows 50 N. W. (another dip
is 38). At 2000' N. W. the dip is 12 S. E. At 3300' the Old Scat bank
worked the same pipe ore horizon ; abandoned for lack of pumping power ;
ore lean, liver colored, like Pennington, but no sandstone ; a good deal of
flint, however, as at Pennsylvania. 1800' furtherup run limestone 9, S. E.
900' further sandy limestone 10 S. E. 1500' further, pipe ore plowed up.
Pipe ore horizon, No. 2, 700' geologically lower' than Old Seat horizon. 1500'
further, sandy limestones,]13, S. E. 3000' to tollgate, no dips exposed, but,
no doubt, all gentle S. E. 1500' S. W. of tollgate, therefore on strike, old de-
serted pipe ore bank ; Pipe ore horizon. No. 3, 550' below No. 2, or 1250' below
No. 1. From tollgate 2400' up run to RR. bridge ; 1200' furtherup, .Bec&and
Town banks, dips in interval 20, 35, etc., S. E. ; therefore, their Penning-
ton range, non-pipe ore horizon, is geologically 2500' to 3000' beneath the
Cale Hollow pipe ore horizon, No. 1, above.
J Here surface ore clays lie on limestone beds which cover lime sandstones.
Three miles N. E. of Juniata river at Barree Forge. One, 200'x75'x20' ;
another, 225'x90'xl2' ; another, 600' x210'x45' ; in places much deeper, and
wholly in wash ore, merely uncovering the solid ore in the floor.
SINKING VALLEY MINES. 399
horizon ; and the pipe ore lies down hill, S. E. geologically
higher, among the non-siliceous magnesian limestones.
Sinking Valley mines.
These are on the Blair county side of the Little Juniata.
Dark colored lime-slate, apparently graphitic, crops out
near Birmingham, and near the axis of the great Nittany
anticlinal ; therefore fully 5000' beneath III.*
The McCahan shafts, % m. S. W. of Birmingham, and
on the same geological horizon, won rich good pipe ore en-
closed in sand, although there is a little yellow clay with
the ore ; the black lime slate is at the bottom of the shaft.
The Robeson pit, 2 m. S. S. W. of Birmingham 100'x20'x-
20' is in Col. Gralbraith's fields, where 4 or 5 acres are cov-
ered with a great ore show. Ore on the Gunnison farm
also.
*The same black slate appears on the Cogan farm 1 m. N. E. of Birming-
ham. The wash ore lumps in clays are all water-worn. Analysis of ore in
T, 246.
400 GEOLOGICAL SURVEY OF PENNSYLVANIA.
Jfittany and Ganoe valleys. Their Jhitidinals and yMiJU
fault at Spruce creek gap of Ihsse^mtn.
a2 Section .
Fault at Port Clinton gap of/fi&aUsiny mtn
CANOE VALLEY. 401
CHAPTER XXXIY.
Canoe Valley and Morrison's Cove limestone and ore.
Canoe valley is not so much a southward continuation of
Nittany valley as it is a long side gallery leading from the
grand hall of Nittany valley into the closed chamber of
Morrison's Cove. A very sharp and very high anticlinal
wave, ending northward in a fault, lifts about 5000' of No.
II, between terrace walls of III and crests of IV, broken by
the two Juniata river gaps ; Tussey mountain on the S. E.
and Canoe mountain on the N. W.
Along the foot of the Canoe mountain terrace runs Jack-
son's fault,* which at the Juniata water-gap above the town
of William sburg, throws the Trenton limestone 3000'
against the Medina sandstone, lapping them horizontally
past each other, and separating thus Short mountain from
Canoe mountain. The fault and the anticlinal axis converge
eastward at an angle of about 15 and die a little beyond the
Little Juniata.
Another fault runs along the south edge of Canoe valley,
and is an interesting study in a topographical sense, because
it has determined the course of the river and the place of
its water-gap at Waterstreet ; cutting off another "Short
Mountain," between the two rivers, f This is the fault
struck in Spruce Creek Tunnel on the line of the P. R. R.
It throws the middle beds of II up against the middle beds
of III in the gap at Spruce Creek Tunnel ; but being
* Studied and described by him in 1838, but wrongly located in direction
and length until our instrumental surveys of 1876 and following years, at
which time 1 extended it to the Little Juniata at Spruce creek station and
discovered its real relation to the central anticlinal. See my small reduced
sketch mapinTS, plate LXIV, page 346, reproduced on a still further re-
duction in this volume, plate XXII. fig. 1.
f Fig. 4 shows the curious and beautiful topography of the Narrows, and
the narrow throat of the Canoe valley at the Little Juniata. Here the anti-
clinal is destroyed by the fault ; as shown in Fig. 5, at the bottom of the
plate, along section on line of Little Juniata.
26
402 GEOLOGICAL SURVEY OF PENNSYLVANIA.
oblique to the valley strike, it carries the top of II against
IV by an horizontal slide movement, so as to enclose a tri-
angular point of III between them ; as shown in the ver-
tical section and horizontal ground plan, fig. 2, on plate
XXII. *
In Canoe Valley proper are the old Clark mine, 1 m. S.
of Etna furnace ; the old Etna mine, 2 m. N. of Will-
iamsburg ; the Brower mine, 3 m. N. W. ; the Short Moun-
tain mine, 2% m. N. W. (and H m. N. of Franklin forge);
Dean's bank, If m. S. ; Patterson 's bank, 1 m. S. W.; and
the Williamsburg M. Co" s Red Ore mines. If m. S. W. of
William sburg.f
* I have added (as fig. 3) a vertical section of the fault in Schuylkill county
for comparison, and have reversed it (N. for S.) in order to make the com-
parison easier for the eye.
f Described and figured in T, pp. 231 to 244. The figures are reproduced,
reduced to half size, on plate XXIIL The Clarkmine, small and long aban-
doned ; ore rather red short. The Etna bank, on the central barren sandy
ridge, 1200' above tide, 400' above the river level, looks down Irom the N.
point of the ridge upon an amphitheatre of cultivated country 150' below it;
5000' geologically below III ; abandoned years ago, 1000'x200'x50' deep ; ex-
ceedingly rich wash ore (not water worn) ; much manganese ore in sporadic
irregular layers ; shafts 112' deep said to have worked rich lump ore ; water
totally wanting. The Broiver mine, 150'x50'x20', now abandoned ; on central
sandy barren ridge ; walls all sand, no clay visible ; many masses ot con-
glomerated angular flint fragments cemented with iron ore, and many
great masses of sandstone and flint coated with ore, as at Springfield mine :
no limestone fragments visible. Limestone strata between it and the Canoe
mountain dip west, and if it were not for Jackson's fault the ore horizon
would be only 2500' beneath III, as given in the text of T, p. 241 ; but this is
a great mistake, for the ore is evidently the Springfield and Etna ore, and
we must understand that 2500 of II are swallowed by the fault, placing the
ore at 5000' beneath III. The Short Mountain mine, described in the text
above, is still worked. Yellow, red and white clays in heavy masses, many
of them without any ore ; ore clays apparently in three stories, with barren
clay partings : (1) upper "sparry ore " in W. wall of E. large open pit; (2)
40' and (3) 60' deep in W. wall rising rapidly to the surface atvop of E. wall.
West pit 60' deep now abandoned. See analysis of ore T, 239 ; and of lime-
stone flux for Etna furnace, in which is C. Mag. 3.9; sulphur, 0.053; phos-
phorus, 0.011. (T. 240.) Dean's bank, 250'xlO' to 50'xlO' to 15' deep. Small
ore in wash ; at E. end cut abutted squarely against solid limestone strata?
mine abandoned ; ore very red short, as used in Williamsburg furnace. See
analysis T. 236. Patterson mine, on the Sandy Central ridge, covered with
quantities of sharp sand ; southern shaft 80' deep, ore struck at 15' and left
in bottom ; ore mass worked 9' thick descending vertically, then at 40' depth
bending to an E. dip ; north shaft 55' deep, ore vertical, taking below an E.
dip; tunnel ore work joins the two ; ore of two kinds, (1) liver ore, often
CANOE VALLEY. 403
It is significant of the decline of the Canoe Valley anti-
clinal northwards that the valley narrows and the bounding
mountains approach each other closest at the Little Juni-
ata. It follows that deeper and deeper horizons in II
reach the surface successively going south along the crest
of the anticlinal, which makes in many places a prominent
central ridge on which are ranged the principal mines.
Now, as we encounter on the map going south no mines
until after passing Water street and Etna furnace, it fol-
lows that the upper horizons are wanting, and that all
the mines are on horizons from 2000' to 5000' beneath III.
Direct cross measurements based on dips verify this con-
clusion, and show that the Etna bank is something less
than 5000', and the Springfield bank about 5000' beneath
III ; while the other side banks are higher in the series.
The Short Mountain mine is a great curiosity for those
who interest themselves with geological structure ; for it
is situated in the narrow belt of the slates of III as they
swing round the point of Short Mountain to meet Jackson' s
fault. But neither black slate nor black clay is to be seen
in the extensive open cuts (which were still worked a lit-
tle in 1876), nor any limestone, but only flints and sand in
abundance in the ore-clays. No solid rock has been en-
countered in sinking an 80' shaft and driving a tunnel
under the old west bank ; nothing but white sand and
sandy clay ; the tunnel entirely in white sand ; yet the
shaft is just south of the south end of the large open mine.
The iron-coated sandstone rock in the open mine dips (ob-
scurely) 46, N. W. The bottom of the ore mass has never
been reached and great quantities remain to be won. The
only explanation of these curious facts which I can suggest
is, that the slate belt is not properly located, and that the
mine is probably on the line of Jackson's, or some other
(branch ?) fault, like the Leathercracker Cove (Henrietta)
mines ; but the ores here do not in the least resemble the
Henrietta ores. On the contrary all the circumstances
silicious, (2) richer deep red or blackish manganiferous ore ; output not
great. See analysis, T, 235. Red ore bank, on the sandy barrens ; northern
pit small ; southern open cut, 40' slope ; red clay holds good redshort ore ;
much flint rock through clay masses. For analyses see T, 233.
404 GEOLOGICAL SURVEY OF PENNSYLVANIA.
here suggest the Etna-Springfield horizon, only that there
is here even more sand and less clay masses.
The red short qualities of some of the No. II ores is ex-
plained occasionally by the presence of pyrites. For ex-
ample, in Dean's ~barik, a shaft 15' deep in the floor of the
open cut went down through loose, partly decomposed lime-
stone and extremely sulphurous iron ore; "in fact, there
were great masses of decomposing iron pyrites, with a
liematite crust." " The solid rock of all kinds in the bank,
whether ore pebbles or limestone pieces, are all rounded
and worn smooth." The Cavern-deposit nature of some of
these ores is shown in the Red Ore bank where shaft No. 1,
just east of the open cut, went down 100' through sandy
limestone, although the ore mass was plunging directly
towards the shaft ; No. 2, just S. of the mine, went 60'
through limestone ; No. 3 and 4, the same. The deep red
clay which makes such a show at the surface at the mine
does not extend beyond it, and no workable surface ores
have been found on the barrens between this and the
Springfield mine, 3 miles further south.
The Springfield mines.
These rival the Pennsylvania and Bloomfield mines.
They are opened on the high, sandy, barren ridge along the
center of Canoe valley,* Similes south of the Juniata river
at Williamsburg, 1500' A. T. A section of the valley from
Lock (Canoe) mountain on the west, across to Tussey
mountain on the east, given in Fig. 13, plate XXIII, will il-
lustrate the low horizon of the ore in II, say 5000' beneath III,
the mine being H miles from the bottom edge of the slate
belt (III) with dips from 20 to 70 between.
There are three pits, two on- the central sand ridge, 1500'
apart, and one in the lower ground, 3000' west of the south-
ern main pit, and 4000' east of the edge of the slate belt
geologically. Ore pit, No. /, is about 4800' beneath III,
but being on W. dips, there are exposed on the crown of
*Here already called Morrison's Cove, although it opens out into the Cove
some miles further south.
CANOE VALLEY ORE BANKS.
405
tna and ffprinqfield T>anJcA.
406 GEOLOGICAL SURVEY OF PENNSYLVANIA.
the arch to the east of it strata more than 5600' beneath III.
How much more lie concealed in the arch can only be
guessed by the little Juniata section, which measures be-
tween 6000' and TOGO' feet and still does not expose the bot-
tom beds of the great formation.
Mine No. 1 (Dams mine), is an open cut, 600'x500'x30'
to 65' deep. It is surrounded by a well denned ore ground
limit, 2600' N. and S. by 300' to 1450' wide, outside of which
the surface is a sandy waste without ore, as both surface
show and trial pits combine to prove. The ores are of
every grade of color, character and value. Fig. 14 of pi.
XXII shows how little of the ore mass has been removed,
chiefly wash ore. Shafts 1, 2 and 3, respectively 65', 100
and 161' deep, show the depth of ore mass, as they strike
the sandstone floor on which the ore mass lies and crops
out to the surface on theE. side of the mine, disintegrating
to a sharp clean sand. The upper sandstone layer is
heavily incrusted with ore, and its small cavities and irreg-
ularities are filled with ore.
The first 60' of wash ore was mined in open cut ; then a
60' shaft went down in lump and wash ore, pitching west
against the sandstone. The wall of the pit must be ex-
cessively steep since this 120' shaft is only 35' from the solid
rock wall. The mine is therefore a cavern deposit, one of
the very few cases wherein a demonstration can be obtained.*
Shaft 3 has the following record : Loose wash ore very
lean in places, clay layers, 40' ; block and lump ore, 2' to
3'; worthless wash sand and clay masses, 112'; ore in white
and yellow clay, 6'; sandstone, massive to bottom (161').
But this record disagrees with every other section in the
mine and may, perhaps, be accounted for by the fact that
the miners were in search of large lump and pipe ore only,
and considered all small- wash ore-ground worth nothing to
them. For on the W. side of the bank, wall and shaft
prove wash ore 120' deep. Elsewhere also the whole mass
is solid but variable wash ore.
It is interesting that loose pieces of sandstone, ferrugi-
*It is possible that it is a small synclinal on the crown of the arch.
(F. Platt, in T, 162).
THE SPRINGFIELD MINES. 407
nous slate, and pieces of sand rock greatly resembling spe-
cimens of IV and V. and conglomerated sandstone frag-
ments held fast by an iron ore cement, are all found in the
ore mass.
Between the Davis and Lykens pits, say 2000', is barren
ground.
Mine No. 2 (Lykens'), is 600'x400'x80' deep (once 100')
encircled by a limit of ore ground. 2200'xlOOO', on the sur-
face. It is worked for the Cambria Iron Co. The Lykens'
shaft at its N. end has a great output. No bottom to the
ore has been reached in the cut ; but the shaft strikes the
sand rock floor at 215'. It works solid ore, that is, great
lumps packed close together in the clay ; usually in two
layers, the upper one reddish ore, then I/ to 4' sand or sand-
stone, then the lower one heavy black lump ore in clay,
resting on the true sandstone floor. Both the ore layers
and the sandstone parting vary much and rapidly in thick-
ness, but in the main rising and falling together conforma-
bly to the irregularities of the sandstone floor. This mine
is remarkable for the quantities of bombshell ore in it, and
for the scarcity of honey comb ore. The bombs are some-
times of great size, some filled with soft white lime clay,
others with more or less decomposed sandstone or sand,
many quite hollow/*
Mine No. 3, is of a totally different character, on a geo-
logical horizon only 2600' beneath III, separated by more
than a mile of barren limestone outcrops, and in limestone
hollows. Its wash ore body contains mostly only small
rounded water worn ore balls. f The open pit 6' to 20' deep
shows only wash ore in caves in the limestone separated by
promontories and ribs of limestone. Fine grained waving
purple or brown or white clays all carry varying amounts
of the ore balls. Dark limestone walls in the whole pit,
and an occasional layer of slate parts two limestone beds.
The floor also is limestone.
But at a place where nearly solid ore made the tempo-
*See other details and numerous ore analyses in T, 163, 167.
f Occasionally some rounded pieces of sandy limestone and limestone are
noticed in this mine also.
408 GEOLOGICAL SURVEY OF PENNSYLVANIA.
rary floor of the pit a horizontal drift followed the ore (S.
E.) for WO' under solid limestone cover, and soon a solid
limestone floor was got also. A 45' shaft from the surface
struck the end of the drift. The ore layer, thus inclosed in
the limestone, when mined averaged 5', but varied between
V and 19'. This is very remarkable as it shows the possi-
ble production of limonite between almost horizontal strata
of unchanged rock. It also shows a sort of broad shallow
synclinal, (or shelf ?) on the western limb of the Canoe valley
anticlinal.
All this agrees very well with the description of the ore
production at the Pennsylvania banks in Centre county,
which are also on the same geological horizon, viz : 2600'
beneath IIT.f
The Prussia mine, small, abandoned, 1500' S. W. of
Springfield No. 2. Tar Hole bank 600' N. W. of the
Prussia. McPheese bank 3000' S. W. of Springfield No.
2, but separated from its ore-area by barren ground ; a
small pot of wash ore.
Canoe valley, at Williamsburg, and at Springfield, is 4
miles wide, [measuring between the two edges of the lime-
stone floor, and 5 between the crests of its bounding
mountains. At Rebecca furnace mines (10 m. S. of Wil-
liamsburg its width is but 3 miles. Here Canoe (or Lock)
mountain swings round to the west, and projects as a broad
round synclinal knob southwards into Morrison's Cove.
The slate on its flank runs on south, in the synclinal as
a narrow belt, past Martinsburg two or three miles. At
Martinsburg and Fredericksburg the limestone land is 3 m.
wide ; this is 12 m. S. of Williamsburg. Millerstown is
\ See further description and numerous analyses in T, pp. 171 to 177. No
limonite mines are more extensive, valuable, or better worked than these
and that is my excuse for so largely extracting from the Report. It seems
that traces of cobalt appear also in these ores, T, 172, 173. See accounts of
plant, machinery, etc., T, 177.
LEATHERCRACKER COVE ORES. 409
14 ; Henrietta furnace mines, at the entrance to Leather-
cracker Cove, 15 ; and the head of the cove 17 m. S. of
Williamsburg. Between Fredericksburg and Millerstown
a belt of slate 2 m. long and m. wide splits the lime-
stone land into two belts ; the eastern one lying along
the foot of Tussey running S. to the head of Leather-
cracker cove ; the western one running on S. past Curry,
Woodbury, Waterside and Enterprise, to the south end
of Morrison's cove. The slate belt is a sharp and faulted
synclinal between the Henrietta (Leathercracker) anticlinal
and the Curry- Woodbury anticlinal.*
Leather cracker Cove ores.
The Henrietta mines in Leathercracker Cove have been
described in a previous chapter on the Limonite ores of
the top of II, but only in such general terms as might
state their possibly very exceptional horizon at the contact
of II-III. This was once considered by others as well as
by myself the true theory. But I am more and more
confirmed in the belief that this is a mistake, and that
they belong to middle horizons of. the formation brought
by the faults into contact with III, as in the case of the
Path Valley mines in Franklin county.
It only remains to notice here the character of the Hen-
rietta ores, referring the reader to Mr. Platt's full details
in T, 183 to 202. PL XXIV, f. 20 maps the main pit,
600'x200'x60' deep, all in ore clay. Projecting boulders
of limestone, much rounded by chemical decomposition,
stand up irregularly on the floor, from around which (as
also from around masses of barren clay) the wash ore has
been removed, f
*On the great map sheets of the Morrison's Cove Survey, in Atlas to T,
this is improperly named the Morrison's Cove anticlinal, and the other the
Canoe Valley anticlinal. In fact, however, both represent the great Canoe
Valley anticlinal in its southern course where its crest is split by a synclinal
roll. The Bloomfield anticlinal is a great wave of the western half of Mor-
rison's Cove. The Woodbury-Curry half of the Canoe Valley anticlinal
becomes the great wave of the eastern half of Morrison's Cove ; the two be-
ing separated only by the wide shallow synclinal of Lock Mountain.
f Some of the main features of the mine are similar to features found in
nearly all the brown hematite deposits of the lower Siluro-cambrian lime-
410 GEOLOGICAL SURVEY OF PENNSYLVANIA.
and <&eatnerc>racfce<r Core
a Rebecca and XCenriettu. furnttcet .
HENRIETTA FURNACE BANKS. 411
Always on the E. side of the pit is the black clay which
ovej'lies the ore mass /* always on the W. side the under-
lying limestone clay / solid limestone W. of the mine,
dipping nowhere more than 30, S. 70 E. But the slope
of the ore from crop to bottom is much steeper; but the
pot which holds the ore is evidently not shaped by the
limestone dip, but is excavated in the limestone, the un-
stones. At times the ore runs in great masses, packed together and like a
regular ore bed ; and this fades out more or less gradually, plainly in sight,
into a clay, carrying perhaps not so much as 10 per cent, of ore in it. The
streaks of clay follow no dip ; they are tolded and rolled in all shapes ; conie
in suddenly and as suddenly entirely disappear; are in places white and
perfectly free either from ferruginous coloring matter, or from wash ore ;
and are again deep red or brown, and sticky.
"But the mine differs from many, in fact from most, ore banks of Morri-
son's Cove, in that it shows no sand, no sandstone, no flint, and no rock of
any kind but blue limestone. But in place of rock and flint some of the
clay layers are unusually sticky, and form balls which pass through the
washer with the ore, and give quite as much trouble as flint in requiring to
be picked by hand.
"There is much iron ore in mine No. 1, which carries varying and some-
times very considerable percentages of manganese. These patches of man-
ganiferous iron ore are very local and very irregular in shape. There is no
guide to say when to expect them, or to indicate when they will run into
the ordinary brown hematite ore. The manganiferous ore chiefly showed
at a depth of about 50 feet below the surface ; and there are now large quan-
tities in the present bottom of the pit. The tendency to run to manganifer
ous iron ore is (at the present depth) much the strongest at the south end
of the mine.
" The ore is usually hard and darker colored in the upper part of the de-
posit, or that nearer to the black slates, while it is apt to be softer and more
open in the lower part, in the limestone. But while this distinction may
hold roughly, yet all kinds of ore, hard, soft, manganiferous, rich and lean,
may be found close together, and in fact mixed together in the same clay
bands." (Platt, T, 186.)
*"The overlying non-ore-bearing dark-colored slates are much weathered
down, almost to a mud, to which condition indeed they soon come on ex-
posure. When first exposed they show as very thin-bedded, fragile, black
slates, fossiliferous in places, though the fossils are kept with difficulty on
account of the fragility of the whole material. Fifteen feet of this black
slate rest on top of the iron ore and clay ; and on top of that there apparently
commences a gray colored, soft, iron-stained, thin-bedded clay-slate, non-
fossiliferous so far as seen. These slates and the surface stuff make a loose
and somewhat troublesome east wall for the mine; the clays holding back
the water and throwing it over the top, the effect being to make the washing
down so severe as to require almost foot for foot as a safe slope tor the east
wall." (F. Platt, T, 190.)
412 GEOLOGICAL SURVEY OF PENNSYLVANIA.
equal dissolution of which waves the ore-mass backward
and forward with gentler and steeper slopes alternately.*
Total excavation 270,000 cubic yards ; total of ore realized
64,000 tons, or 16 per cent, of the stuff excavated. All
goes to the Cambria Iron Works at Johnstown.
The Faulkner shaft, 1200' S. of main pit ; mouth 40'
higher than surface at main pit ; depth of shaft 153', with
ore left in bottom ; ore struck first 40' down ; output 10,000
tons ; abandoned. Three monkey drifts found the descend-
ing ore mass to be 25', 25', and 40' from wall to wall. Drift
S. from bottom of shaft, 400' to 500', showed the curious
structure of Fig. 22. f
The McAUster shaft, 2700' S. of Faulkner shaft, still
following line of fault ; 100' deep ; black clay hanging wall ;
limestone clay foot wall ; ore clay 15' to 20' thick, vertical,
irregular.
The Hoover mine, 750' S. of McAllister shaft ; open cut
200'xl25'x30' deep ; shaft, 120', struck some ore near bot-
tom ; black clay in E. wall of open cut ; W. wall lime clay,
and back of it limestone ; % ore clay 15' to 20' thick, unusu-
ally sticky and troublesome.
This Henrietta ore range is a well denned, limited and
local deposit of ore clays in a fault-trench 7000' long, 15
to 35' wide and of unknown depths, between a wall of
black (Utica ? or Hudson river. Ill) slate, on the one side,
and a wall of dolomite strata belonging to some unknown,
probably middle horizon of Chazy or Calciferous formation
II ; both walls thoroughly decomposed into black and white
clays ; without the intervention of any igneous rock like
trap as at Cornwall, but, perhaps, by the hot waters from
a great depth, as at the Hot and Warm Springs along the
*The analysis of limestones given in T, p. 1888, show that they are almost
perfect dolomites (53 : 35 and 57 : 39.
fThe ore clay forked, one part going straight on, the other curving
round, carrying rich ore all the way until it rejoined the other ; black clay
horse (without ore) Jfl' wide. Black clay is the hanging wall and limestone
clay the foot wall in all the Faulkner shaft workings without exception.
Ore dark and hard, especially towards the hanging wall ; foot ore more cel-
lular. See analysis T, 192. fhosphorus too high, 0.940.
J Also here a dolomite (46:40) which of itself precludes the theory of this
ore being made out of damourite slates at the contact of II and III (T, 196).
LEATHKRCRACKER COVE ORES. 413
great fault in Virginia. But it is not at all necessary to
suppose the water hot or even warm ; for the process was
evidently the same at the other limonite mines of this region
where no faults exist. The ordinary solvent powers of the
rainfall are quite capable of carrying on the operation,
which in fact it is doing all the time at the present day.
Nor is a cavern deposit here in question ; for the ore mass
here is not made up of rounded pebbles ; nor can any other
water worn detritus be seen in these mines.*
The Leathercracker (Henrietta) ores are too phosphatic
for the Bessemer process. Three analyses of samples from
the three Cambria Co.'s mines, show : Sesq. ox. iron, 60,
63.6, 69.4; Sesq. ox. mang., 3.5, 1, 0.3; phos. acid, 0.822,
2.153, 1.021, etc. (T, 197). But they are high in iron,
cheaply mined, and kind in the furnace ; were in great de-
mand for stock mixtures so long as iron rails ruled the
market ; but have declined in value in this new age of steel
rails. Thomas and Grilchrisfs basis process may, perhaps,
restore their old value.
The Schoolhouse mine on the W. side of Leathercracker
cove, on the other fault line, is described in T, 199. See
Fig. 22a.
The Bolster mine of "neutral ore," 3 m. N. of Wood-
bury ; two open pits, separated by the road, 100'x60'x20',
long abandoned and a smaller pit ; ore rich, very sulphur-
ous ; great masses of decomposing pyrites ; unusually red
clays ; no water ; no solid rock ; ore lumps not rounded ;
many rounded flints and limestones ; geological horizon
about 2500' beneath III, that of the Pennsylvania furnace
mine in Centre county.
*"The ore is in lumps of all sizes, ranging from large and heavy masses
closely packed together until they resemble a bed of ore, to fine grains thinly
disseminated through various colored clays. But all the ore pieces are ir-
regular in shape and with points and angles, sharp on the corners, and in
many cases coated with little needles of ore, which the smallest friction
would soon rub oft'. This is the unvarying character of the structure of the
ore lumps and grains in Leathercracker Cove." (Platt, T. 197.)
414 GEOLOGICAL SURVEY OF PENNSYLVANIA.
Morrison Cove ores.
The Bloomfield mine on Duncan's ridge, 3 m. S. of
Hearing spring (where its branch railroad joins the line
from Henrietta mines to Hollidaysburg) is famous for furn-
ishing stock to Bloomfield, Sarah, Martha and Rebecca
furnaces, making the best gun metal for theU. S. foundry
at. Pittsburgh.
Halter's creek flows between Duncan's ridge and Dun-
ning's mountain. The Lock mountain anticlinal of Mor-
rison's cove runs E. of the mines ; very gentle E. dips into
the Martinsburg shallow and broad synclinal ; overturned
steep E. dips (instead of normal W. dips) at the mines and
in Halter's valley and in Dunning mountain. A slip fault
is probable but not demonstrated. Depth of ore horizon
beneath III, (calculated) 3200'; therefore 700' lower down
than the horizon of Pennsylvania and 1800' higher up than
the Springfield ore horizon.*
The reader will find a fully detailed description of the mine
in Mr. F. Platt's Report on Blair county T, 1881, p. 203 to
221. All along the valley between Duncan's ridge and
Dunning mountain runs a belt of ore clays, from 1 m. N. of
Roaring spring southward past the Bloomfield school house,
Bakersville ore pit, Long's, to the Stukely farm, a distance
of 7 or 8 miles ; in some places slight, in others heavy, but
none but that at Bakersville promising a great yield.
The Bloomfield ore clays are continuous for 7200', from
the N". end of the German bank to the S. end of the
Clarke banks, with a width of 1000' to 1500, across
the top of Duncans ridge. f The larger clay masses are
more than 100' deep. The ore ground ends abruptly
* I have placed the cross-section showing mine, anticlinal, etc., on the
Bloomfleld mine map, plate XXV, page 415. The Loop mountain anti-
clinal is described in T, p. 63, etc. ; the mine in T, p. 203, etc. Dunning's
mountain has a strike of N. 22 E. but the anticlinal axis runs nearly due
N. into the Loop, and through to Frankstown.
f The map shows where the greatest output has been made, but many
trial shafts found nothing but very lean sand and clay. The water shaft and
boring, 225' deep, went all the way through sand and clay, with no solid
rock beds, and no water, and ended in sharp sand. Trial pits just north of
German bank went through solid rock without ore.
MORRISON'S COVE ORES.
415
r\ \ \\
ny.z4.
Section from DunnuigsAElJiroaghBloomfieldMfms.
416 GEOLOGICAL SURVEY OF PENNSYLVANIA.
northward at the German bank. So also south of
the Clark bank solid limestone is at the surface. But in
the mines no limestone ribs are seen and none were struck
in intermediate trial shafts and borings. It looks as if the
ore mass were the filling of a vast cavern, which has lost
its roof. In spite of the long time working of the mine,
only a portion of its wealth has been extracted.*
The mine shows the usual great and sudden changes in
the character of the ore bearing mass ; a iion-ore-bearing
clay will suddenly change into a rich wash ore deposit,
* The Main bank, including the German, is 1800'x 100' to 400' x80' deep. In
1880 it was beingworked with renewed vigor (See T, p. 205). The Harrity
open cut is 350' long. Its clays are beautifully stratified, dipping 10, E.
"white clay caps the ore-bearing clays with the same dip, and requires 25' of
stripping. Over the -white clay ore-clays are worked for 200' along the
strike (N. and S. ). This same white clay is struck in shafts N. and S. of the
bank. No better evidence of change of rock in situ could be got ; and yet
the sudden N. and S. termination of the field does not look like it ; unless a
change in a character of the anticlinal is taken into consideration. Some of
the clays are blood-red ; occasionally they hold manganese, as, for example in
shaft 500' S. of main bank, from which manganese ore was shipped for
spiegeleisen. Usually these shafts brought up manganese ore that was too
sandy for use. The New Wash Machine bank. Here 2' of sand makes a layer
between ore-bearing clays, and as regular as a sandstone bed. The Sand
bank in a sandy barren surface soil, has 15' siliceous ore in sandy clay, 15';
underneath which yellow and brown clays holding not much ore ; then
brown clay holding excellent mang aniferous limonite masses packed
in the clay so as to warrant the miners in calling it a 4' bed. TheRidgt
banks are numerous pits S. of the Sand bank ; the main one large ; ore out-
crop heavy; sand and flint on the surface but very little in the bank itself ;
good ore in yellow clay goes deep ; shafts 60'; lump masses closely packed
in clay still in bottom ; miners merely followed these lump streaks. In a
new pit white clay has many scattered quartz crystals in it. The Krofft
banks are further south. The Clarke banks come next; ore mass solid 4
to 9' at 40' beneath surface ; in S. Clarke bank another at 100' deep. (T, 211.)
If the surface lean silicious stuff 15' to 20' deep were stripped, systematic
mining here would yield an enormous quantity of good ore. The Old
Barley bank, \^ m. S. of Clarke bank, abandoned. Stuckey and Leidig
banks, 2^ m. further S. shallow and hopeful. The Bloomfield plant, ma-
chinery, washing and method of working the mine, are all described in T,
pp. 212 to 214. For numerous analyses of the ore (as received at the fur-
naces) by McCreath, Wuth, and Salom, seeT, pp. 214 to 219. The Rodman
Furnace "gun metal" pig, made in 1872, 1874, showed : Silicon 4.004, 3.184,
2.713; Sulphvr, 0.035, 0.082, 0.123 ; Phosphorus, 0.195, 0.195, 0.192 ; Mangan-
ese, 0.144, 0.864. It was used in the Bessemer flasks of the Pa. Steel Co. at
Baldwin. Captain Rodman, U. S. A., urged the U. S. Government to secure
by purchase the whole Bloomfield ore field. (T, 229.)
MORRISON'S COVE MINES. 417
and vice versa ; while masses of sandstone, coated with
oxide of iron, or flint pieces large and small come into
the ore mass and leave it without any visible law. Some-
times there are huge walls of tough sticky clay in sight
bearing no iron ore ; and again almost everything is wash-
able. The mine therefore does not differ from the other
ore deposits of Morrison's cove in the character of its de-
posit, but only in the unusually enormous quantities of
iron ore in sight and in their freedom from phosphoric
acid" Consequently the Cambria Iron Works at Johns-
town was taking (March, 1879) all the jigged Bloomfield ore
although they called it only a 39 per cent. ore. Phosphorus
is not wholly absent from any of the analyses, and traces
of both cobalt and nickel appear in some of them. Sul-
phur is usually present in small quantities, but in some is
quite absent.
It is noteworthy that both sulphur and phosphorus ap-
pear in all three of the Rodman furnace limestone flux
analyses given in the Report (T, 218) thus : Garb, lime,
78.2, 91.9, 54.6; carb. magnesia, 10.7, 2.9, 44.2; ox. iron
and al., 1.8, 0.6,0.2; Sulphur, 0.149, 0.096, 0.002; phos-
phorus, 0.029, 0.022, 0.003 ; insol. residue, 8.6, 4.4, 1.3.
Other mines in Morrison's Cove.
The Baker smile mine, 2 m. S. W. of the Bloomfield mine,
is in the valley W. of Duncan's ridge, and therefore on
geologically higher outcrops, but in a heavy surface wash
ore deposit 1500' N. and S. by 400' E. and W. No solid
rock in place has been struck by any of the trial shafts 75'
deep. The deep, narrow valley has probably once been an
immense cavern, like Sinking Creek cavern in the northern
part of Blair county. The open cut is 300'x45'xl5', in sand
and sandy clay, yellowish, sometimes reddish, holding ore
balls from top to bottom ; not a single piece of loose lime-
stone ever found ; many large pieces of sandstone, coated
with an iron crust, not rounded and worn (as a rule), nor
are the rounded ore chunks ; nor do they follow any line,
nor make layers, but are scattered through the whole sand-
27
418 GEOLOGICAL SURVEY OF PENNSYLVANIA.
clay mass ; ore, of all varieties, water- worn rich dark lumps,
porous honeycomb ore, dark red solid somewhat sandy
ore, light brown lean sandy ore, and light brown rich ore.
(T, 220.)
The Miller -stown Red Ore bank, 1 m. N. E. of the vil-
lage, large, shallow, long-abandoned ; wash ore, in which
knobs and masses of undissolved limestone make an irregu-
lar floor ; clay deep red ; ore, limestone and flint pieces gen-
erally if not always rounded and water-worn, usually small,
never in large masses ; shafts reported 100' deep in ore to
bottom. Belt of red clay surface extends several miles N.
& S. but no trial pits have ever found ore except at this
one spot, the size of the mine ; evidently a cavern deposit.
Analysis by McCreath : Iron, 54 ; manganese, 0.065 ; sul-
phur, 0.017; phosphorus, 0.085. Calculated ore horizon
only 1100' beneath III.
The Rebecca ore mines, 3 m. N. 70 E. of Martinsburg,
were worked for 60 years for Rebecca furnace.* An open
cut 80() / xl25' to 300 / x70 / and more (now only 50') parallel to
to Tussey mountain ; W. and N. walls solid non-ore-bear-
ing white clay dipping (apparently) 70, E. S. E. oner which
clays holding masses of bombshell ("copper shell") ore,
lean, brown, sandy, worthless (because only 15 per cent,
iron and stained with copper oxide). Worked 4 years by
shafts, as shown in section, plate XXIV, fig. 27. f
The Thompson mine, I m. S. of Martinsburg ; shallow
holes furnishing cellular, fibrous and sometimes pipe ore ;
many honeycombed ; somewhat red-short. Horizon (cal-
culated} about 2500' beneatJi III, i. e., about the horizon of
the Pennsylvania bank in Centre county.
* Described in T, 223 ; surveyed in 1877. See map and section of it in Fig.
27, 28, plate XXIV. Worked continuously lor Rebecca from 1817 onwards ;
consequently a very large output.
f Barren white clay 80' deep at top of main shaft (i. e., 50' or 60' thick)
ore clay, 50' ; ore mass, 15'. East shaft found only white sand and no ore.
The ore is not in water worn or rounded pieces, but in irregular masses and
chunks, sharp pointed, surrounded by clay. Ore has always made a first-
class metal ; much of the war gun metal was made from it.
VALLEYS AND COVES OF NO. II. 419
CHAPTER XXXV.
Other anticlinal limestone valleys and coves hi the middle
counties: Friends cove; Mllligen" s cove ; Kishicoquillis
valley ; Blade Log valley ; McConnellsburg cove ; Horse
valley.
Friends cove.
Friends Cove in Bedford county is connected with the
southern end of Morrison's Cove by a narrow, anticlinal
strip of slate No. Ill between Dunning (Evitts) and Tussey
mountains*. Itslimestone floor is 15 miles long, by 3 miles
wide; ending northward in a point 4 m. N. E. of Willow
Grove; and southward in two points, at Rainsburg, a village
on the contact of Utica slate (Ilia) and Trenton limestone
(lie). The lower Medina sandstone (TVa) makes a terrace
all round the Cove, as in Morrison's Cove and Nittany Val-
ley. The limestone rocks at Rainsburg dip 20, *S. 55 E.
At Chaiiesville near the N. W. side of the Cove, a local 8,
S. 55 W. dip shows that the formation is disturbed. The
Cove is divided by a middle ridge of very sandy limestones,
which proves the general steep dips by bringing up the
lower portions of the formation ; and the sand eroded from
these outcrops covers the surface of the Cove to a great ex-
tent, concealing the outcrops, and any deposits of limonite
ore which they may hold. Occasionally a piece of ore may
be picked up. Cove creek flows along the S. E. edge of the
limestone; has a broad bottom reaching to the foot of Tussey
mountain; and shows no exposures, only here and there a
little water-worn limestone; but is covered with bowlders
of limestone and sandstone from the mountain. Some lim-
onite was seen by Prof. Stevenson on WeisePs farm 1 m.
S. of Koons' mill.f
* See Geol. Atlas of Counties, Report X, 1885, Map No. 5, preface descrip-
tion, p. 24.
f A specimen from Koons' quarry gave carb. lime, 90.6; carb. mag., 1.9.
ox. iron and alumina, 0.6; sulphur, 0.02; phosphorus; 0.005; insol., 6.41. Mc-
Creath in T2, 163. Of course the quarry is in Trenton lie.
420 GEOLOGICAL SURVEY OF PENNSYLVANIA.
Much chert occurs on the central ridge in irregular frag-
ments, with here and there abed of limonite ore, evidently
little of it. On L. Whetstone' s farm ore is said to be plenty ;
cindery chert is abundant ; and the sandy soil is full of
Medina sandstone fragments, and also pieces of Hudson
river slate. On the adjoining Diehl place and in A. Whet-
stone's fences there are plenty of pieces of ore.
Between this and the Juniata river many exposures of
limestone show dips of 27 to 35, S. 85 to 40 E. and lime
is burned for manure.* The road along the S. side of the
river has plenty of limestone exposures ; and shows a good
deal of ore where it crosses the middle barren sandy ridge.
From the railroad cuttings Prof. Stevenson obtained the
following section.
Limestone (45 E.) dark above, lighter below ; some beds
magnesian ; very little chert ; fossils few (S. alt., Lep. ser.
Gal. sen.} ; 430'; Limestone, (40 E.) light grey to blue
above, growing silicious and cherty downwards, until at the
bottom the chert makes the mass; 1350' : Concealed, 420';
Limestone, (dip 45 E.) 420' ; Concealed, 400' ? ; Limestone,
silicious, 175'; Concealed, 150'; Limestone, very cherty,
300'; Concealed, 90'; Limestone, sandy, with very little
chert ; a true Calciferous sandstone, 175'; total, 4520' of
measures not reaching the bottom of No, II. f
Milligeri s cone.%
Milligerts Cove in Bedford county, is about 10 miles long
and a mile wide, very long and narrow, floored with Hudson
river slate (UK), except at one spot in its center, where
the sharp anticlinal brings up the upper beds of Tren-
ton limestone (He). The Utica slates (Ilia) are exposed at
Miller's dipping 35, S. 35 E. near the exposure of Trenton
limestone. Of course there are no limonite mines in this
cove4
* Trenton limestone, holding the fossils Strophomena alternata and Caly-
nene senana (T2, p. 163).
f Stevenson's Report T2, pp. 93, 164.
jStevenson's Report T2, p. 108.
Also spelled Millikin's and Milligan's
VALLEYS AND COVES OF NO. II. 421
KisMcoquillis valley.
Kishicoquillis Valley, making the N. W. half of Mifflin
county, is a beautiful, fertile valley, secluded between Jack's
mountain and Standing Stone mountain. At its eastern end
it is split by two long promontories into three narrow par-
allel vales, each of which has an anticlinal floor of the
slates of III. The limestone floor of the valley itself is about
27 miles long by 2 wide opposite Reedsville and Milroy, 2 at
Belleville and Menno, and 1 at Allenville near the Hunting-
don county line.*
Two anticlinal waves lift the valley limestones ; a third
passes behind Milroy. The Greenwood fault cuts obliquely
through Stone mountain, N. of Belleville, and throws the
terrace of IVa against the mountain of IVc. f
The limestone beds along the center belt of the valley lie
remarkably flat, so that erosion has not yet gone deep into
the formation. In Logan Gap, through which Kishico-
quillis creek escapes from the valley to join the Juniata
near Lewistown, there is a well exposed section of S. E.
dipping Medina and Oneida strata (IV) measuring 2,722
feet. Under these lie Hudson river slate and sandstone in
four divisions, 425', 190', 140', 182'; and Utica shale in three
divisions, 210', 302' ; 855' ; making III in all 2304' thick.
Under these are exposed only 320' of Trenton limestone at
the surface.
The Greenwood ore banks were excavated on the anticlinal
axis south of Belleville. At Belleville are dips of 15 to
20, N. W. and 10 near the mine. Much pipe ore was got
here and carried across Stone mountain to the furnace to
mix with fossil ore there mined. But the bank was aban-
doned many years ago, partly on account of the cost, and
partly from lack of ore, w r hich was only found in pots and
pockets in the limestone. Many such pockets were ex-
ploited in early times in other parts of the valley; but all
*See Geol. Atlas of counties, Report X, 188?>, p. 77, and the map of Miftiin
county in the same Atlas, No. 41.
t DescribecTin detail and with special maps in Report T3. The valley is de-
scribed hy d'Invilliers in his report F3 and the fault on p. 239. It will be
hereafter described in the chapter on Oneida and Medina sandstone forma-
tion N. IV.
422 GEOLOGICAL SURVEY OF PENNSYLVANIA.
mining was long ago abandoned. No doubt there is this
good geological reason for a scarcity of ore, viz: that the
valley erosion had not been carried down deep enough into
the magnesian (Chazy) part of the formation.*
The fact is, the Trenton is so thick and the dips are usu-
ally so low, that the Chazy has but little chance to reach
the present surface. On the other hand the limestone
quarries of the valley are all excellent, and the Trenton
beds furnish also hydraulic limestone, on which at Milroy
a large plant is now (1891) being established, f
Black Log valley.
Slack Log valley in Huntingdon county (its N. E.
end in Mifflin) is 20 miles long, by 1 mile wide, and on a
gentle curve4 It is a fine specimen of the class of valleys
and coves of limestone and slate produced by the erosion
of the high steep compressed rock waves of Pennsylvania.
In this case the anticlinal had a double crest, which it
shows at the present surface ; but it is probably a single
simple sharp anticlinal underground. The breadth of
limestone at Orbisonia gap is only 2600' feet ; and the thick-
ness of Trenton limestone about 500'; from under which rise
only the upper beds of the Chazy (lib) on the two crests of
the wave. |
The fact that no limonite ore has been found in Black
Log Valley goes far to support the view that there is really
* D'Invillier's Report F3, 1891, p. 237.
t There are, however, steep dips in some places. On the creek road from
Belleville to Union Mills the beds dip 65 and 68, S. 55 E. At the quarry
on Yoder's farm the stone looks more like slate than limestone; and this is
the characteristic feature of the Trenton beds in middle Pennsylvania. The
Trenton is in fact a transition formation from the magnesian II to the argil-
laceous III. The Utica slate here dips 60, N. W. (T3, 238).
JSee Geol. Atlas of Counties, Report X, 1885, Map of Huntingdon No.
31, and preface descriptions, p. 57.
A cross-section will be given in a future chapter.
j| The Grove quarry seems to show the limit of the Trenton beds down-
ward, and the top bed of the Chazy, by the following analyses in Ashburn-
er's Report F, 1876, p. 260. Carbonate of lime in top bed (22" thick) 90.16.
Then follow downwards 84.68, 89.68, 74.18, 81.18,82.60,80.68,82.18, 85.18, and
then the bottom bed, only 46.68, which may be assumed as the top of the
Chazy.
VALLEYS AND COVES OF NO. II. 423
no limonite horizon at the junction of II and III ; that is,
at the top of the Trenton, and at the bottom of the Utica.
McConnellsburg cove.
TheMcConnellsburg cove in Fulton county, is a canoe-
shaped valley with pointed N. E. and S. W. ends, enclosed in
mountain walls of Medina sandstone(IV), with slopes of Hud-
son river slates (III), and a fertile floor of limestone (II), 13
miles long by 2 miles wide. It differs from all the other
coves in having along its N. W. side a profound fault, the
limestone (II) being upthrown 80CO' against Devonian strata
(VIII). This fault swallows up the slate (III) and sand-
stone (IV) and consequently destroys the mountain wall on
the N. W. side of the cove.*
The limestone beds at McConnellsburg and between that
village and the school house dip 55 towards the fault (W.)
and are mostly silicious, with much honey-comb chert, and
so red a soil in some places as to suggest a good deal of
limonite iron ore. At Sargent's Rocks, in the southern
end of the Cove, are the extensive old limonite banks of
the Hanover Iron Works, worked for about 25 years, and
abandoned in 1847. The annual yield of ore is said to have
varied between 1200 and 2000 tons, and much ore is sup-
posed to remain. Its horizon is high in the formation.!
The furnace got also some ore from the Patterson place, on
the eastern road towards the pike, and trial pits were sunk
on the Nelson farm, but all such work was abandoned forty
years ago; and the development of the ores of the Cove is
still to be made.
The underground erosion of the limestone strata is vari-
ously illustrated in the Cove. Its south end is drained by
Esther's run, heading in the high vale between Cove
and Dickey's mountains. In about 4 miles it sinks, and
rises again in the Big Spring ; then cuts through the Me-
*A description of the fault is given by Stevenson in his Report T2, p. 55,
56 ; and details of its exhibition in his subsequent chapter XIII on Ayr, Todd
and Dublin townships, T2, p. 291 et seq.
t Analysis by McCreath: Iron, 46.1; sulphur, 0.115; phosphorus, 0.083; sil.
mat, 21.5 (T2, p. 296).
424 GEOLOGICAL SURVEY OF PENNSYLVANIA.
dina ridge, and joins Cove creek between the Lutheran
Church and Elysian Mills.*
Horse Valley.
Horse Valley at the S. W. end of Perry county, con-
tains a narrow belt of limestone land, with two points or
prongs at its north end, where the anticlinal has two crests,
and only one point at its south end, where the anticlinal is
simple. It is one of the branches of Path Valley in Frank-
lin county, and almost its whole floor is made by the slates
of III. Occasional pieces of limestone have been found
near the gap.f
* The drainage of the Cove is very curious as shown on the colored map of
Fulton county in Report T2. The natural course of Esther's creek would
have been around the N. end of Lowrie's Knob instead of through a gap in
the ridge (IV). So also at the northern end of the Cove, the drainage ought
all to flow south past McConnellsburg into Cove creek. Instead of that, it
gathers itself by streams that flow N. as well as S. and W. into Licking creek,
which breaks a gap through the Medina mountain (IV) at Knobsville.
f See Geol. Hand Atlas, Report X, 1885, Map No. 45, and Preface p. 85.
Dr. Henderson made the top beds of II reach the surface. But Prof. Clay-
pole could not satisfy himself of the fact, and drew his cross-section as if
the limestone did not See his Report F2, page 352, and his section on page
350, which I reproduce in a future chapter.
CAVERNS IN NO. II. 425
CHAPTER XXXVI.
Caverns and sinkholes in II.
The whole surface of the limestone belt of the Great Val-
ley is pitted with sinkholes in the farmers' fields. By these
holes the rainfall escapes into caverns, which ramify in all
directions both along and across the stratification, and re-
appears in springs in the beds of the deeper valleys. This
explains the scarcity of brooks and creeks on the maps of
the limestone belt in the Great Valley ; and on the maps of
Kishicoquillis and Nittany valleys and their branches, and
the limestone coves of Fulton and Bedford counties.
Many ancient caverns are now dry, the drainage having
opened for itself new ones. Others have been deserted be-
cause completely choked .and filled with lime-iron clays and
ore. Others have been exposed to the sunlight by the fall-
ing in of their roofs, and converted into vales by the solu-
tion of their walls. Those which were filled with deposits
arid then uncovered form the limonite iron mines of the
present day.*
*A most instructive case is described by Prof. Ewing in his special report
embodied in Report T4 on Centre county, at page 418. I give his descrip-
tion verbatim, as follows :
''Cavern deposit of iron ore. On Sinking creek, as it rounds Egg hill, in
Potter township, on the Wagner place (A. Kerr, in county atlas), is an ex-
posure of ore quite unique in many respects. The ore occupies caverns
eroded out of the limestone. In this exposure most of the limestone is left
intact. The ore that has been removed has been taken from openings into
the solid mass where erosion has removed the material from one side. Even
there it is necessary to remove large quantities of limestone in order to get
the ore. Large masses of pipe ore are found, with lump ore, bomb shell ore,
and wash ore. Most of the ore taken out has been removed from one large
triangular space, having sides about 20 feet in extent, and a depth of 15 feet,
one side forming an opening from the bank of the creek-bed. Besides this,
several small test-holes, drift, and slant openings have been made. Those
within a range covering not more than 20 or 25 feet in thickness of rocks
strike ore of the same character ; those out of this range show but little ore.
The ore is found in the worn joints imbedded in a tenaceous red or yellow
clay.
"As pipe ores are undoubtedly formed by the evaporation of chalybeate
426 GEOLOGICAL SURVEY OF PENNSYLVANIA.
Shifting creek in Blair county offers a fine example of the
extensive underground chemical erosion of limestone beds
in the upper part of No. II. Its Arch spring became
famous among the white settlers at an early date.* The
waters, which percolate through the mass, one might expect to find in a
place like this evidence as to the time of the formation of these pipes. The
fact that all are broken off none being attached to the limestone implies
that they were formed at a sufficiently remote period for subsequent waters
to dissolve away the attachments. The fact that the pipes are straight and
generally parallel, implies that they were formed while the rocks were sta-
tionary, and not during a gradual upheaval. It is inconceivable that they
were formed while the rocks were in their original horizontal position ;
hence, it is altogether probable that they were formed after the Appalach-
ian upheaval, and while the rocks were in their present position, that is,
dipping 45 S. E.
"One very interesting specimen from this region has one of the pipes at an
angle of 40 with the rest. I think it probable that in this case the pipe had
broken in falling, and had been cemented by subsequent depositions of the
same material, as there is abundant evidence of later depositions in thread-
like pipes at right angles with the larger ones.
"As previously remarked, the probable condition of the ore while in so-
lution, and at the time of deposition, was that of a ferrous carbonate. It is
probable that oxidation began at the time of, or soon after, deposition. When
the deposition was rapid, masses of carbonate and semi-carbonate were
doubtless formed, which have subsequently been oxidized. Evidence of
this is seen in the larger masses found, especially here, of ore containing
cavities, giving it a porous appearance, often called bomb-shell ore ; for as
the carbonate of a low specific gravity changes to the oxide of a higher spe-
cific gravity thei-e is a loss in volume. The change naturally beginning from
without forms concentric layers of the oxide and leaves cavities within.
Even the pipe ore is more or less porous."
* Captain John S. McKiernan, who moved from Blair into Clearfield, sent
to the Tyrone Herald, March 11, 1886, the following slip from a very old
newspaper : "Among the other curiosities of this place, is the swallows
which absorb several of the largest streams of the valley, and after convey-
ing them several miles under ground, in a subterraneous course, return
them again to the surface. These subterraneous passages have given rise to
the name 'Sinking Spring Valley.' Of these the most remarkable is called
Arch Springs, and runs close upon the road from the town to the fort. It is
a deep hollow, formed in the limestone rock, about thirty feet wide, with a
rude natural stone arch hanging over it, forming a passage for the water,
which it throws out with some degree of violence, and in such plenty as to
form a fine stream, which at length buries itself in the bowels of the earth.
Some of these pits are near 300 feet deep ; the water at the bottom seems in
rapid motion, and is apparently as black as ink, though it is as pure as the
finest springs can produce. Many of these pits are placed along the course
of this subterraneous river, which soon after takes an opportunity of an
opening at a declivity of the ground and keeps along the surface among the
rocky hills for a few rods, then enters the mouth of a large cave, whose ex-
CAVERNS IN NO. II. 427
creek rises on the high ground of the Kettle at the south
end of the valley, and flows along the exis of the anticlinal
for 3 miles ; then works over to the east side of the valley
and flows in the upper limestones at the foot of the mount-
ain for two miles ; disappears in a large sink hole and
flows underground a mile, its "hollow" or surface channel
being dry. Another creek, heading near the Bald Eagle
mountain, on the west side of the valley, and flowing square
across it to the hollow, meets a brook descending from the
east mountain terrace and flows one or two miles further
along the hollow, according to the wetness or dryness of
the season, and disappears gradually through a succession
of sinkholes. A third creek starts in the center of the val-
ley five miles north of the last mentioned, flows across east-
ward 1^ miles, enters a large cave, flows under its roof 4200
feet, issues from a picturesque arch at the N. E. end of the
cave, and thence flows through a flat to the river at Union
Furnace.
Elk run follows the opposite or N. W. outcrop of the
same limestone beds at the foot of Bald Eagle (Brush)
mountain, cutting a deep narrow trench to the river at
Tyrone forges ; and this trench merely represents a similar
series of sink-holes and caves which have lost their roofs.
All the brooks descending from the terrace further south
than the head of Elk run, fora distance of two miles, sink
as soon as they pass the edge of the slate belt and enter the
limestone land. Of course their waters rise somewhere to
terior aperture would be sufficient to admit a shallop with her sails spread.
In the inside it keeps from 18 to 20 feet wide. The roof declines as you ad-
vance, and a ledge of loose, rugged rocks keeps in tolerable order on one
side, affording means to scramble along. In the midst of this cave is much
timber, bodies of trees, branches, etc., which being lodged up to the roof of
this passage, shows that the water is swelled up to the very top during
freshets. This opening in the hill continues about 400 yards when the cave
widens, after you have got round a sudden turning point (which prevents
its being discovered till you are within it) into a spacious room, at the bot-
tom of which is a vortex. The water falls into it, whirling round with amaz-
ing force ; sticks, or even pieces of timber are immediately absorbed and
carried out of sight, the water boiling up with excessive violence, which
subsides by degrees until the experiment is renewed."
428 GEOLOGICAL SURVEY OF PENNSYLVANIA.
augment Elk run ; just as all the waters of the Sinking creek
system issue at Arch Springs.*
A cave in Gregg township, Centre county, is described
by Prof. Ewing as typical of the many which ramify be-
neath Nittany and Brush valleys. It is about a mile west
of the end of Brash mountain ; on the 43 S. E. dip of that
synclinal ; in dark blue limestone, possibly near the middle
of formation II. f
The "Hollows" of our limestone country are not ordi-
nary valleys of erosion but unroofed ancient caverns. This
is apparent from their peculiar shape, and the fact that
many of them are dry, that is, have no flowing streams,
but are studded with sink-holes into which the rainfall dis-
appears to caverns beneath them which have been subse-
quently formed. Prof. Ewing describes one known as the
Big Hollow, in Centre county.:}:
*Fine pictures of these arches and caves were made by Prof. Rogers' ac-
complished Swiss artist, Mr. Lehman, and published in the Geology of Penn-
sylvania, 1858, Vol. I. They will be found (reduced) in a future plate.
f In Report T4, p. 442. " The entrance is from a deep sink. It extends
along the strike of the rocks and contains deep clear water. It is suffi-
ciently large to allow navigation in a large row-boat Its height in places
is 20 or 30 feet, and its breadth about the same. The roof of the cave is
formed for the most part by one thick stratum of limestone. In places,
however, this has fallen away, leaving exposed the strata above. The cave
extends 1200 feet beneath the surface. At the far end the rocks dip in a
more easterly direction, so that the roof comes down to the surface of the
water. About 300 feet in, the cave divides into two parts, one wet, the other
dry, the same stratum forming the roof ot both. The side toward which the
rocks dip contains the water, the more open side apparently having its
bottom filled by the d&bris fallen from above. The two arms are separated
by a natural partition of uneroded rocks. The dry cave may be reached by
another sink in line with the opening alluded to. Within the cave are stal-
agmites and stalactites of every variety of form.
"About 80 feet from the far end of the cave is a deep ravine, and the
Fathomless /Spring known as the source of Penn creek. As the water in
the spring stands at the same level as that in the cave, the two are probably
connected ; and the cave is no doubt only one section of a much larger sys-
tem of underground drainage ; for, a short distance nearly west of the cave
a stream sinks beneath the surface, and is probably identical with that which
appears as Penn creek."
JT4, p. 442. "Several beds of ancient streams are noticeable in this lo-
cality. One of the most extensive of these appears to originate near Johns-
ton's ore bank. Here several indistinct depressions converge into one ravine
which crosses the road passing northeast of Struble's bank. The Bellefonte
and Buffalo Run RR. grade follows this ravine to thecurve near Thompson's,
CAVERNS IN NO. II. 429
Of the innumerable limestone caverns of Pennsylvania
very few have been explored, most of them are inaccessi-
ble, and the existence of a great number of them is only
indicated by sink holes in the farm fields.
One of the most interesting is the Hartman cave (now the
Crystal Hiil cave) in Monroe county, which was explored
in 1880, and found to be floored by 10' of clay, on which
was spread a thin layer of stalagmite, and on this again a
foot of black earth containing the teeth and bones of ani-
mals of both extinct and living species, mostly broken,
splintered and gnawed by large and small carnivorous beasts
which at one time made the cave their home, dragging into
it their prey to be devoured.*
where a branch ravine joins it ; which the grade follows upward, diagonally,
through the Barrens. This ravine is traceable to the vicinity of the Pond
bank.
"The main ravine, known as Big hollow, continues in a sinuous course
northeastward until it reaches Spring creek, one mile below Houserville.
Big hollow has a distinct course of about five miles ; its banks are in places
from 50 to 100 feet high, here sloping and gradual, there steep and precipi-
tous. As in the case of real river channels, the steep banks are on the inside
of the curves.
" The whole topography of Big hollow indicates that it is the bed of an an.
cient stream. An extensive area slopes toward this ravine. Several smaller
ones join it on its course, yet I know of no evidence that water has flowed
through it since the first settlement of Centre county ; but I have found
numerous sink-holes along the channel ; and gravel deposits and other de-
bris in the vicinity of some of them indicate that large quantities of water
have flowed into them in times of freshet ; and this makes it probable that
there exists beneath the Big hollow an underground channel joining Spring
creek."
*The report of the exploration, made by Mr. Paret, Prof. Porter and Dr.
Joseph Leidy, was published in the Annual Report of the Geo. Sur.Pa. for
1887, pp. 1 to 20, with two plates by Dr. Leidy, who identified the remains of
the living lynx, gray fox, wolf, skunk, weasel, raccoon, mole, dusky bat?
little brown bat, woodchuck, porcupine, beaver, musk rat, gray squirrel,
ground squirrel, meadow mouse, white footed mouse, wood rat, gray rab-
bit, deer, elk ; no domestic animal, except perhaps a pair of imperfectly de-
veloped teeth of a horse ; many bird bones, especially of the wild turkey
several kinds of turtles and snakes ; snail shells, a valve of the river mus-
sel, and two other shells ; some small fragments of charcoal ; many seeds
of dogwood, pignut, walnut ; works of man, a bone fish hook, harpoon
head, 5 bone awls, a bone needle, a bored cone shell, a chipped spear head
of argillite, a black flint knife and a piece of brown pottery.
But with all the above were found remains of the extinct peccary (Dicoty-
430 GEOLOGICAL SURVEY OF PENNSYLVANIA.
A vertical cavern in the limestones of II was exposed by
quarry work in the Chester county valley near Port Ken-
neday, and explored by Mr. Wheatley, of Phoenixville ;
the animal remains being described by Prof. Cope. These
were all of a comparatively recent geological age. This
fact, taken in connection with the Tertiary lignite beds of
the Pond bank in Franklin county, and the Ironton mine
in Lehigli county, prove that all our caverns are of geologic-
ally modern construction, and belong not at all to the re-
mote dates of the limestone formations which they pene-
trate ; that they are in fact the last descendants of an infi-
nite series of caves excavated in successive ages, and un-
roofed and swept away as the unceasing erosion by atmos-
pheric waters lowered the original surface of the globe to
its present level. The rate at which this erosion has gone
on deserves consideration.
The rate of erosion.
The rate at which the surface of our limestone valleys has
been lowered is hard to calculate. It depends (1) on the
amount of rainfall from year to year and from age to age ;
(2) on the way the rain falls, whether in a perpetual drizzle,
or in violent downpours ; (3) on the slope of the beds of the
water channels, whether more or less steeply inclined ; (4)
on the solubility of the rocks, both in general and in par-
ticular, determining the shape and size of caverns, the sta-
bility of their roofs, and consequently the amount of me-
chanical erosion which is in addition to the amount of
chemical solution.
Undoubtedly a part of our limestone formation passes off
to the ocean as lime water ; but another part passes off as
broken matter, floated limestone pieces, limestone sand,
limestone mud. And when the new oceanic deposit is
made it must represent both these forms ; as we see that it
does ; for the microscope shows mechanical fragments
cemented by a chemical precipitate.
les pcnnsylvanicus) ; of another larger extinct peccary (Platygonus vctus};
and of the extinct gigantic beaver (Castoroides ohioensis.*)
This cave, not being in No. II, but in the lower Helderberg limestone No.
VI, will be more properly described in a future chapter.
CAVERNS IN NO. II. 431
The chemical solution of the limestone strata of Centre
county was studied by Prof. A. L. Ewing in 1883*, at the
upper end of the Old Bellefonte dam, below the entrance of
all visible tributaries of Spring creek. (1) The cross-sec-
tion and velocity of the stream were here measured ; (2)
the amount of solids in the water was determined by evapo-
ration ; (3) the area of the whole water basin was calcu-
lated geographically.
1. The average width, 75' ; average depth (six measure-
ments), 2.7' ; average velocity (got by bottles floated at va-
rious depths), 3263' per hour = about 24, ,500 cubic yards
of water passing a given point every hour.
2. By evaporation (two tests), 2400 grains of solid matter
were got from one cubic yard of water ; according to which
(24,500x24x365x2400-5-7000=) 73,584, 000 Ibs., or 328,500
long tons of solid matter carried away per annum.
3. The area drained by Spring creek is rudely estimated
at 100 square miles, three-fourths of which is mountain
slope ; the rest limestone valley. By evaporating mount-
ain water it was found that nine-tenths of the solid matter
in Spring creek came from the limestone valley.
Prof. Ewing calculated the annual waste of the region at
282 tons per square mile ; and the waste of the limestone
valley by solution at 275 tons per square mile.
Taking the specific gravity of limestone at 2.75 (Traut-
wine, p. 386), a layer one foot deep over a square mile would
weigh 2,140,540 gross tons. A layer of 275 tons would be
only one-eight thousandth (^oW) f an mc ^ thick. In
other words the surface of Nittany valley is lowered at the
rate of one foot in eight thousand years by the loss of what
is constantly running off past Bellefcnte, so far as that can
be calculated in the manner described above.
Other things, however, have to be taken into considera-
tion which should vitiate the correctness of that result
without substituting for it another more reliable. The
loose stones in the main channel and in all its branch water
ways show that annual floods play a role of great import-
*Proc. Am. Ass. Adv. Science, 1884; copied into Report of Prog. G. Sur.
of P., T3, 451.
432 GEOLOGICAL SURVEY OF PENNSYLVANIA.
ance in the operation ; frost loosening the limestone slabs,
and water breaking them into pieces, grinding them to-
gether, and sweeping them away into the Susquehanna
river and so onward into the sea. The rate of this mechan-
ical destruction of the surface is unknown, and probably
cannot be in any manner calculated. It' it be assumed equal
to the rate of chemical solution, the surface of the country
may be said to lower itself one foot in 4000 years.
But even this more rapid rate cannot be adopted for cal-
culations extended backward many ages ; for, while the
chemical solution is a constant quantity, provided the an-
nual rainfall be a constant quantity^ the rate of mechanical
erosion depends on the velocity of streams, i. e. on the slope
of the water-basin. But this was much greater in past
ages than it is now. When the top limestones on the Belle-
fonte and other anticlinals were first laid bare the general
surface of the region had a topography exactly resembling
that of the Shade and Black Log region at the present day ;
but it had an elevation above the sea at least 5000 feet
higher. Of course erosion went on at its usual high rate
in Alpine regions ; but as we have no data for calculation,
it is left to the imagination of the student of nature to
adopt a mean rate between the extremes of excessive me-
chanical erosion at the outset and of excessive chemical
solution now.
At present the water fall from the head of Spring creek
(1290' A. T.)* in Penn's valley to the dam at Bellefonte is
only about 57C', and from Bellefonte to tide water in Chesa-
peake Bay about 720' At the birth of Nittany valley the
fall of the Spring creek which then traversed it lengthwise
(as Black Log creek traverses its valley) was say 500', and
of the Susqnehanna river which then existed say 5000'.
The rate of surface erosion may well have been then 400 or
even 100 years per foot.
All such calculations are therefore fruitless, seeing that
the age of Nittany valley can be made at will either 40, 000,-
000, 20,000,000, 2,000,000 or only 500,000 years. If we go
back beyond the uncovering of the top limestones of No.
*T4, 419.
CAVERN DEPOSITS IN NO. II. 433
II on the Bellfonte anticlinal to the coal age, we greatly
increase the time, but not in proportion to the thickness
of the overlying formations ; for, the erosion must have
been vastly more rapid when the surface stood 20,000' or
25,000' above the sea.
In fact this part of our science is nothing but a fairy
tale ; and the best geologist is merely the most lively ra-
conteur.
Precipitation of limonite in caves.
The rate of deposit of limonite (hydrous peroxide of
iron) in cavities is sometimes, under favorable circum-
stances, quite rapid. For example, at the Bennington
shaft near the Allegheny mountain summit tunnel of the
P. RR. in Blair county "the pump column" receives from
the mine water one inch of such deposit each year, supplied
by the decomposition and oxidation of carbonate iron ore
balls in the roof shales of the Miller coal bed. And again,
at Johnstown, in the Slope mine, an area of half an acre
(near New Furnace No. 5) is now being filled with limonite
mud from the same source (viz : decomposition of ore balls
in roof) so rapidly that a layer 18 inches in depth has been
made in the course of the last eight years ; so that it looks
as if the whole space once 'occupied by the coal bed would
in a few years more be occupied by a consolidated bed of
limonite iron ore.*
*The process is facilitated in this instance by the fact that some warm water
from the large furnace works passes through the roof of the mine. (Report
T, p. 171.)
The deposit of iron rust in the municipal purifying revolvers at the Ant_
werp water works is accompanied by physical details of the greatest inter-
est for geologists studying the theory of the formation of limonite deposits,
including organic matter, clays of various colors from white to black, and
concretions. "In March, 1885, three of these revolvers were started at Ant-
werp, and the original iron and gravel beds were converted into ordinary
sand filters ; by this change the capacity of the works was at once doubled.
The total weight of iron in use at one time was reduced from 900 tons to 3J
tons, and all the expenses connected with digging over and washing the
purifying materials were done away with.
"When pure water is passed through a revolver, a certain amount of iron
is dissolved, and then the water flows out a light gray color. After two or
three hours, the color changes to a reddish brown, and a deposit of rust
28
434 GEOLOGICAL SURVEY OF PENNSYLVANIA.
Depth of limonite deposits in caves.
The depth of a limonife ore-clay mass therefore depends
on the depth of the cavern floor ; and this in turn depends
upon the deepest drainage level of its district.
Theoretically such a deposit of ore ought not to be deeper
than the place where its ancient water course came out on
the Lehigh or Schuylkill river, but, considering the chem-
ical action of the water on the floor of the cavern, and in
fissures descending beneath the floor, some slight additional
depth must be allowed. It is a practical geological rule,
however, that an owner of ah iron bank in fterks county
cannot expect to find ore below the plane of 200' above tide,
which is the level of the bed of the Schuylkill at Reading,
and the level of the bed of the Lehigh at Allen town. An
allowance must also be made for the grade of the descent
of the underground water from the mine to the outlet. An
iron bank near Reading maybe deeper, therefore, than one
at Kutztown or at Womelsdorf can be. Topton Junction,
for example, stands at 485' A. T. Subtract 200' from 485'
takes place at the bottom of the vessel. If filtered at once on escaping from
the revolver the liquid will generally be clear at first, but after a time it will
sometimes get cloudy and the deposit of rust will take place, showing
that the iron existed in the first instance in solution, and was
afterward precipitated by the action of atmospheric oxygen. If the
water be impure, colored and charged with dissolved organic matter,
it will issue from the revolver of a dark gray color, and this will increase
to an inky black in the case of very bad water. So that it is possible to judge
of the quality of the water by the color assumed during its treatment. If
the impurities are not more than the iron can deal with, the liquid, on stand-
ing for some three or four hours, becomes lighter and lighter in color, a
black precipitate forms, and sinks very slowly to the bottom, the color be-
comes a dirty gray, and then the water will filter quite clear and bright. If
the impurities overpower the iron, or are of a nature which the iron cannot
effectually attack, a purplish color remains, and the liquid will not filter col-
orless. As in the case of the Bischof filter, the time of repose and exposure
to the air before filtration is obtained by providing a sufficient depth of
water over the sand of the filter beds.
"In addition to its chemical action, iron possesses the property of causing
the very finely-divided particles of matter, which cause opalescence and
cloudiness, to coagulate to such an extent that they can be removed by fil-
tration. The waters of the Nile, for example, which will not subside clear'
in any reasonable time, and which cannot be filtered bright by sand filters,
yield a beautiful clear water if agitated with iron before filtration through
sand." Sci. Amer. Supp., No. 580, p. 9260, Feb. 12, 1887.
CAVERN DEPOSITS IN NO. II. 435
and we have 285' as the possible depth of a cave or sink-
hole. But Topton Junction is 18-J miles from Reading. If
we only allow a fall of 5' per mile for the cavern waters we
must take off 92', leaving only 193' for the possible depth
of a cave, or of an iron ore deposit at Topton Junction.
Beyond some such properly calculated depth sinking for
iron ore of this kind is a hopeless affair.
The filling of the caverns, however large and numerous
they may be, is easily comprehensible when we remember
that an average of 93 per cent, of the magnesian limestone
formation rock is soluble, and when dissolved by the rainfall
passes off entirely into the sea. Of the remaining 7 per
cent, of insoluble clay-iron sand, a portion would be carried
away by rapid waters, but a portion would settle and remain
in quiet pools in the large cavern chambers, and would en-
tirely fill such galleries as were kept full of water by the
choking up of their lower exits.
Limonite precipitated from pyrites.
Enough is said on this subject on preceding pages lo
suggest inquiry, for no sufficient knowledge of it has yet
been obtained. Dr. T. S. Hunt has expressed his opinion
strongly that all our limonite deposits have had this origin.
But the frequent finding of crystals and pipes of pyrites in
the ore banks is not of itself a broad enough basis for so
large a generalization, and many of the facts narrated in
preceding chapters seem to have no direct connection with
such a process. The presence of magnetite, however, is a
detail which may be connected with that of pyrites.*
*Mr. W. B. Devereux, of Colorado, has published in Trans. A. Inst. Min
Engineers, Feb., 1884, an interesting paper on the Pitkin county iron ores-
which he concludes with the following paragraph : " While in doubt as to
the relation this ore-body bears to the limestone, I hazard the opinion that
the magnetite is a direct product of the decomposition of iron pyrites, and
that the ore-body at no great depth is massive pyrites instead of massive
magnetite. I base this opinion upon the following facts : Crystals of mag-
netite are common in this locality, which are pseudomorphs, showing the
common hemi-hexahedral form and characteristic striations of pyrites. Efflo-
rescence of ferrous sulphate is also common ; and in the bed of the ravine
the ore is a mixture of pyrite and magnetite, the latter appearing as a fine-
grained gray matrix, and, when pulverized or broken off, being strongly
436 GEOLOGICAL SURVEY OF PENNSYLVANIA.
CHAPTER XXXVII.
Zinc, Lead and Barium in No. II.
New Jersey has its great Franklin zinc mine, famous
throughout the mineralogical world as well as the world of
commerce and the arts. Pennsylvania has its one great
Saucon mine of zinc ore, also ; and two other zinc mines of
no commercial importance, but equally interesting from a
geological point of view ; all three being precipitations of
salts of zinc in the same old limestone formation of No. II.
The Saucon zinc mines of LeMgh county.
The location of these mines is shown on plate XII, page
364, above. They have riveted the curious attention of geol-
ogists for many years, as they have given occasion to some
of the most splendid exhibitions of mining engineering
genius, in its efforts to overcome extraordinary difficulties
in the way of drainage. The mine pumps are among the
greatest in the world. The most powerful apparatus that
could be constructed was required for keeping the great
excavation dry enough to work. The limestone formation
in the Saucon valley lies in a deep trough into which, and
to the bottom of which, flows the rainfall of the surround-
ing mountains. The beds are uptilted and broken, the
innumerable fissures which traverse them and the caverns
which have been excavated in them permit the accumulation
attracted by the magnet. This rapidly increasing percentage of pyrite, the
occurrence of the two minerals in intimate juxtaposition, and the fact that no
intermediate stage of hematite occurs, taken together with the testimony of
the pseudomorphs, all oppose the application to this case of the ordinarily
accepted theory that magnetite is a metamorphic derivative from hematite.
Having enjoyed a somewhat extensive observation of iron-ore deposits, and
accepting, as satisfactory in many cases the theory just mentioned, yet in this
case I can see nothing which will permit its use as an explanation of the
i'acts. This ore contains a trace of silver also, but no copper. It may be in-
teresting to note that pieces of the limestone referred to, when struck with
a hammer, emit the odor ofsulphureted hydrogen."
ZINC MINES IN NO. II. 437
of great quantities 'of water; the dissolution of the lime
rocks has produced concentrated masses of zinc ore ; and
the phenomena of our great brown hematite iron ore de-
posits are here repeated, zinc being substituted in the place
of iron. The geological cause of this substitution of zinc
for iron may be said to be quite unknown, or at all events
has not yet been satisfactorily explained on any theory ; nor
can we suggest a reason why some of the beds of No. II in
Saucon valley are as heavily charged with zinc as are the
iron-bearing beds of No. II elsewhere in the State with
iron. If it be suggested that the zinc has come from a dis-
tance, whether from above or below, it is only necessary to
point to certain thin beds of limestone, carrying zinc which
have been mined to a small extent and without profit in
the neighborhood of Penningtonville in Lancaster county,
and of similar beds of limestone carrying both lead and zinc
which have been repeatedly mined without profit in Sink-
ing valley in Blair county. In the last mentioned district
of the State two sorts of unwise notions have been expressed
regarding these zinc- bearing beds. (1) They have been
looked upon as merely veins descending into the interior
of the globe. Similar veins of zinc ore do in fact exist in
Sinking valley, opposite Birmingham, but they are concen-
trations of the zinc and lead from the limestone beds of the
valley, and (2) there is no good reason for believing that
they are connected in any way with the underground
depths. They have nothing to do with the anticlinal struc-
ture of Sinking valley any more than the zinc ores have
with the monoclinal structure at Penningtonville, or than
the zinc ores have with the synclinal or basin structure of
the Saucon valley. The fact is, that zinc and lead seem to be
inherent constituents of all limestone formations the world
around. It is probable that they were deposited with the
limestone in far grater abundance in ancient ages, and were
originally brought into the Appalachian sea as soluble
salts, together with the lime and magnesia waters of prim-
eval rivers. It only remains to add, that the zinc and lead
ores of Pennsylvania correspond in all respects to the No.
II zinc ores of Wythe county, Virginia, and to the great
438 GEOLOGICAL SURVEY OF PENNSYLVANIA.
lead and zinc deposits in the fissures and caverns of the
ancient limestone country of Wisconsin and Missouri.
They all belong to the same remote age, and have been con-
centrated into their present form in the same limestone
formations and by a similar process.
The Saucon zinc mine at Friedensburg is said by Rogers
to be in a close synclinal fold.* He describes it as merely
a surface quarry ; but it had only been started in 1853, and
worked three years by a slope when he saw it. Its calamine
ore or silicate of zinc, appeared then irregularly injected
into the limestone, which stood vertical in the N. wall, and
dipped 85 in the S. wall. The limestone was also injected
with thin veins of quartz."f
Prof. Prime in his Report D3, 1883, p. 239, says the ore,
zinc blende, associated with iron pyrite, is disseminated
through a limestone which seems broken up, and its crevices
filled in with the ore.
The mass has somewhat the appearance of a breccia. The
zinc blende is not confined to one bed or horizon, but ex-
tends through a vertical thickness of 30 or 40 feet in some
places, while at other points of the mine the infiltration
seems confined to a vertical thickness of 10 to 20 feet.
The mine has been worked (1877) to a depth of 250' on the
slope of the bed. The excavations are very large and ex-
tend along the strike more than 1000'; the dip of the lime-
stone being 30 to 35, S. 5 to 10 E.
It is evident that the source of the ore was above, and
not beneath ; that the term "infiltration" is as justly used
in this case as in that of our limonite or brown hematite
iron ore deposits. That the zinc was an original constitu-
ent of the limestone is extremely doubtful. And yet the
fact that the zinc of Pennsylvania and New Jersey, as well
as of the western states occurs in No. II. seems to link the
metal with limestone of Lower Silurian age. The notion
of a deep-seated source expressed by Mr. F. L. Clark in his
*Geol. Pa. 1858, p. 101. On page 236 he suggests that the synclinal may
be faulted.
f The ore was smelted at Bethlehem and converted into white paint. The
vein seemed to range along the axis of the synclinal or fault, 1856.
ZINC MINES IN NO. II. ' 439
paper on the Mining and Metallurgy of Zinc in the U. S.,
published in the "Engineer and Mining Journal" of Sep-
tember 8, 1883, I cannot concede to ; but his description
of the mines is perhaps the best we have, and I give it in a
foot-note.*
* The zinc deposits in the Saucon valley, Lehigh county, Pennsylvania,
which were once extensively worked, now produce but little ore. Their
history, however, has a special interest from their connection with the in-
troduction of spelter-making into this country, and from the fact that they
belong to a class of deposits which seems to warrant a belief in their con-
tinuance to a considerable depth, and because they are a good illustration
of the general effect of the characteristic feature of the ore market above re-
ferred to.
Tbree principal deposits have been discovered, known respectively as the
Ueberoth, Hartman and Saucon mines : they occur in magnesian limestone
of the Lower Silurian formation, and have many points in common, while
they also present some striking differences. They were all at one time
owned or controlled by the Lehigh Zinc Company, whose works were at
Bethlehem, four miles distant.
The Ueberoth mine, which is, so far as developments have shown, the
largest, was worked continuously from 1853 up to the fall of 1876. It was
for many years the main dependence of these works, and produced in the
neighborhood ot 300,000 tons of ore. The strata of limestone are here very
much disturbed and tilted up almost to the vertical, apparently by the ob-
trusion of the syenite ridge of the neighboring South mountain. The ore
came close to the surface, and a very rich pocket was found in the clay
above and around limestone boulders, which is estimated to have produced
100,000 tons of ore. When this body of ore was exhausted, the ore was fol-
lowed down in crevices between the boulders. These crevices lie in planes
parallel to the bedding of the limestone, or in planes perpendicular to it, and
preserve great regularity in their position, an i a parallel course for several
hundred yards in a northeast and southwest direction ; they are nearly ver-
tical, and at the depth of 225 feet, to which the mine was worked, showed no
signs of closing up. The ores at first were exclusively calamine and smith-
sonite ; but at greater depth blende made its appearance, coating the walls
of the crevices, and in some cases penetrating into them several feet ; in
other cases, segregated as rich seams, which nearly filled the cross-openings.
At first, it was confined to the northeastern end of the mine; but at the low-
est depth reached it could be traced almost continuously to the extreme
southwestern end. The dip of the ore body appeared to be regular, and to
the southwest. Six of these parallel crevices were worked, and about as
many crossings ; and where they intersected, rich bunches of ore were
found, some of which were as much as 60 feet across and 20 feet thick. All
the indications seemed to point with increasing certainty to the existence of
a backbone or underlying deposit of blende, out of the reach of the action of
meteoric waters, from the continuation of which the oxidized ores have been
derived.
Timbering the mine was always a serious difficulty, but the greatest ob-
stacle to be overcome was the water. Even at a depth of 40 feet, the flow
440 GEOLOGICAL SURVEY OF PENNSYLVANIA.
Bamford zinc 'mines in Lancaster County.
In the northern part of East Hempfield township, Lan-
caster county, limestone beds impregnated with almost in-
was already very strong ; at the depth of 150 feet, it was found necessary to
put in what was then the largest pumping engine in the world. This en-
gine, which is a single cylinder, double-acting, condensing, walking-beam
engine, with a pair of fly wheels, has a 110-inch cylinder and a 10-foot stroke,
and is calculated to work four 30-inch plunger pumps and four 30-inch lift
pumps, with 10-foot stroke, and to take water from a depth of 30 feet. At
the time it was stopped, it was running from six to seven strokes a minute,
and was working three pairs of 30-inch pumps and one pair of 22-inch pumps,
and was easily handling all the water that came to them. The pump-shaft
and foundation for the engine were no less remarkable in their way. The
latter was built up from the solid rock, 60 feet below the surface of the
ground, of hewn blocks of Potsdam sandstone ; the former, which measured
30 feet by 20 feet in the clear, was started on a small crevice, and timbered
with 12-inch square yellow pine sticks, and divided into three compart-
ments, and further strengthened by two open brattices of the same heavy
timber. When the pitch of the vein carried it out of the shaft, the rest of the
depth was sunk through solid rock.
The Hartman mine distant about half a mile, was worked at first ex-
clusively for calamine. Its exploitation gradually exposed a central horse
of blende, which the method of mining adopted made it necessary to leave
for the support of the timbers which carried the roof. The increasing im-
portance of this blende at the lowest level worked, 150 feet, caused a change
to be made in the method of mining. The mine was operated for a year
after the large engine was stopped, and the last work that was done was the
putting in of a slope to develop this deposit of blende. The water in the
Hartman was always less strong, the pitch of the crevices less steep, and
the surrounding rock less disturbed than in the Ueberoth mine ; the strike
of the crevices was more to the west, and the blende came nearer to the sur-
face.
The Saucon mine, however, affords the simplest and best illustration of
this form of deposit. It is distant about a quarter of a mile, and was origi-
nally leased by the Passaic Zinc Company, by whom it was sub-let to the
Lehigh Zinc Company on high royalties. When the rich deposit of calamine
first discovered was apparently exhausted, this sub-lease was surrendered
by the latter company, and in 1875 the original lease passed to the Bergen
Point Zinc Company, by whom the mine has been worked ever since. A
face of blende was uncovered at the western extremity of the open pit, and
the ore followed under a heavy cap of limestone for a distance of 250 feet
up to the property of the Lehigh Zinc Company on the west. On this pro-
perty, it was reached at a depth of 110 feet, under 100 feet of solid limestone,
and was followed 150 feet farther on the course of its strike. On both pro-
perties, it was followed to a depth of nearly 200 feet. In the fall of 1879, all
the property of the Lehigh Zinc Company passed into the hands of its bond-
holders under foreclosure of its mortgages, and in the spring of 1880 all the
mining property was sold to the proprietors of the Bergen Point Zinc
Works.
The workings of these two mines, taken together, show a remarkable
ZINC MINES IN NO. II. 441
visible zinc blende, dipping about 70, N. 15 W. at the
surface and S. 15 E. in the deep, are described in Dr.
regularity of width, pitch and course, and the deposit is clearly shown to
be a large chimney or chute of ore of irregular cross-section, which, how-
ever, preserves a lenticular shape, the longer axis of which is about 60 feet,
and pitches to the south at an angle of about 30 degrees ; the transverse axis
measures about 30 feet. The axis of the ore-body dips to the west-south-
west with a slope of about one foot in four. The weathered outcrop has
evidently given rise to the pit of oxidized ores ana to certain irregular de-
tached deposits which lie in the same course, several hundred yards beyond it.
Here, then, are three similar deposits of zinc ore, with their nearly parallel
chimneys of blende and their corresponding beds of calamine, which have
evidently been brought up from below, by solution in thermal springs,
through crevices formed in the limestone by the gradual upheaval of the
neighboring South Mountain, and have undergone subsequent alteration
from the action of meteoric waters. Nearer the mountain, where tbe strata
are most tilted and the ground most disturbed, the water is strongest and
the largest deposit of calamine is found. In the Hartman mine, the strata
are more nearly flat, the blende is sooner met with, and the water is much
less strong ; and in the Saucon mine, the blende is met with at the edge of
the pit, and only moderate-sized pumps are required in working it at a depth
of 200 feet That the water in these mines comes from the same surface
springs which supply the Saucon Creek, is evident from the fact that, when
the big mine was abandoned, this creek shrank at once to a small fraction
of its former volume, and only gradually recovered it as the mine filled up.
Very careful surveys of the bed of this stream failed to discover any point
at which it showed any diminution of its volume or seemed to sink into the
ground. It is, therefore, very improbable that the water, having once come
to the surface, found its way back into the mine. It was probably tapped in
under-ground courses connected with the springs which give rise to thecreek.
This is the more probable, as the mine which has the most water is on the
highest ground and is farthest from the creek, and the mine having the least
water is nearest the creek. It is therefore reasonable to suppose that nearly
the maximum quantity of water likely to be encountered was already
handled, and that, if a solid body of underlying blende were developed, it
could be profitably worked with the machinery already in place. The
Saucon mine is still the main dependence of the Bergen Point Zinc Works,
but its continued working must be attended with increasing cost and uncer-
tain risks.
The ores of this region are remarkably free from lead, arsenic and antimony,
and it is this circumstance that gives them their principal value and interest,
and has been the basis of the very high reputation of the metal and oxide
obtained from them. Only the richest of the ores are, in the present state
of the ore market, available as spelter ores, but even the leanest of the
oxidized ores produce a very fine quality of oxide. The blende is very
peculiar. It is massive, and rarely shows even traces of crystallization ;
when pure, it has a bluish slate color, has a very characteristic conchoidal
fracture, is translucent on thin edges, and gives a clear ring when struck.
As generally sent to the works, it resembles broken limestone ; is somewhat
mixed with iron pyrites, and assays from 35 to 40 per cent of zinc. It is not
442 GEOLOGICAL SURVEY OF PENNSYLVANIA.
Frazer's Report C3, p. 55 At the west end of open cut
No. 1, a shaft was sunk cutting two or three belts rich in
easy to concentrate, both on account of its non-crystalline structure and of
the pyrite it contains.
The causes which led to the extinction of the Lehigh Zinc Company and
the abandonment of the first two-named mines were briefly these ; the im-
possibility of competing successfully in the oxide market with the owners
of the big mine in Sussex county, New Jersey, after the expiration of the
patents covering the oxide process left them free to take the trade, or in the
sheet-zinc and metal market with the Western smelters, using cheaper and
richer ores, at a time when a general depression. of all manufacturing enter-
prises made it unusually burdensome to carry the heavy bonded indebted-
ness incurred during a period of high prices and general inflation in acquir-
ing mines and putting up machinery to work them. Under more favorable
circumstances, it is probable that these mines could have been profitably
worked for years to come ; for although the pumping expenses were heavy>
they were not excessive, considered as a royalty on the ore, and these
charges per ton would diminish in proportion to the amount of ore mined.
Now, however, it will probably be left for another generation to discover
what value they still have.
Other deposits of zinc ore have been discovered in the same Silurian for-
mation in Pennsylvania, Maryland and Virginia, which have been worked
from time to time, but have produced very inconsiderable amounts of ore.
Small oxide works were built at an early day near Birmingham, Blair
county, and at Landis station, in Lancaster county, Pennsylvania, but they
were soon abandoned. At the latter point, shallow beds of rich carbonate
of zinc were first discovered, but were worked out. About 1876, expensive
concentrating works and two blocks of spelter-furnaces were put up, to
treat the grains and kernels of c^stallized blende scattered through the
underlying limestone, before sufficient exploration was made to warrant
such an outlay of money ; they have for years been lying idle.
Mr. J. Eyerman, furnished the same journal December 15, 1883, the follow-
ing interesting particulars: As the ore (calamine,smithsonite and sphalerite)
in this mine is near the surface, it is not, at present, difficult to work. The
calarnine is found in large quantities disseminated through the limestone.
It is found mostly on the north side of the mine, where it is worked by a
small force of men.
This mine has furnished, and will continue to furnish, the finest speci-
mens of calamine (or silicate of zinc) known to the world. It is very often
found in botryoidal and stalactical forms. It is not seldom that sheets or
plates of calamine from two to three feet square and from one-eighth to one-
fourth of an inch thick, and containing thousands of little crystals on the
surface, are found between the crevices of the limestone. Again, it is found
as a thin coating to the inside of a quartz geode. This ore is quite scarce at
the Endy mine. It seems to have been replaced by the blende. The smith-
sonite or carbonate of zinc is found in white scales and in granular masses,
coating calamineand blende. It is also more commonly found as a brownish
earth, which hardens when dry. It is found near the center and along the
west side of the mine. It has often been mistaken for clay. This is also
mined at present by a small number of men. The sphalerite or zinc-blende
ZINC MINES IN NO. II. 443
zinc. The east end of cut No. 2 showed the vein striking
N. 85 E. In a small open cut m. W. of RR. bridge over
Little Conestoga creek 80 tons of sandy limestone impreg-
nated with calamineand blende, and seamed with calcite,
were taken out ; dip apparently 50, N. 10 E. ; but on the
RR. the limestones dip 8, N. 5 W.
The Bamford mine was worked for a white oxide between
1850 and 1860. Streaks of silver lead are found in the lime-
stone, which is about 12' thick.*
Mr. E. G. Spilsbury's letter respecting the mine (C3, p.
198) describes two parallel beds of the limestone, near the
slate, but not at the contact of the two formations, as in
Blair county, " unmistakably bedded veins, and not fissure
or gash veins ; conformable both to the stratification and
dip of the inclosing rocks ; " striking N. 74 E. and dip-
ping 72, N. 15i W.
The hanging wall limestone is a breccia (or crushed) par-
tially decomposed, whitish gray, and highly silicious ; full
of seams, cavities, and small caves (15' to 20' long and as
many broad, by 4' to 6' high), all completely filled with a
dark red sandy loam, and not with mineral as in Missouri
and Illinois. In none of these loam-filled "cavities have I
ever found a trace of mineral." The broken condition of
the roof limestone extends from the surface to the bottom
of the pump shaft 110'. The foot wall is not uniformly
smooth but has offsets, like layers, shelving downward over
and past each other and into the ore body ; or, in other words,
the ore passes up between these shelving layers of dark
blue limestone sometimes to a distance of 8 or 10 feet. (See
figure in C3, p. 199.) The foot wall limestone is less silici-
ous, dark blue, in places almost black, and very close and
is not mined. It is found throughout the mine, with pyrite disseminated
through it. It is not met with in as large quantities here as at the Endy
mine. Greenockite (sulphide of cadmium), hydrozincite, and goslarite
(sulphate of zinc) are met with in smaller quantities. The sulphate of zinc
is scarcely ever found. A considerable quantity of greenockite has been
mined. It is found as a yellowish powder coating blende and limestone.
It was formerly separated at the LJethlehem works.
* Notes by P. Frazer, July, 1876, C3, p. 196, give details of crushing and
roasting.
444 GEOLOGICAL SURVEY OF PENNSYLVANIA.
compact, with occasionally small holes lined with ealcspar
and frequently filled with specular iron ore.
The minerals in the vein matter consists of the two sul-
phides of zinc and lead ; changed for about 18' beneath the
surface to calamine and carbonate of lead ; unchanged sul-
phides below. The vein matter or gangue itself is a lime-
stone very like that of the foot wall, but crystalline in
spots. The galena (sulp. lead) is found in bunches or little
strings running along on or near the hanging wall ; but the
Jjlende (sulp. zinc) impregnates the whole vein matter, more
or less thoroughly.
The percentage of silver in the galena varies wonderfully
from $2 per ton in one bunch to $2,000 in the bunch next
to it ; a general average may be perhaps $22.*
Sinking Valley zinc and lead mines in Blair county.
These are described by Mr. F. Platt in chapter XV of his
Report on Blair county, T, 1881, pages 247 to 277, only a
short summary of which can be given here, the reader
being referred to the original report.
Sinking valley is the triangular south end of Nittany
valley, south of the Little Juniata river ; 10 miles long by
5 wide at the river ; anticlinal in structure, the axis sinking
southward, as shown by Figs. 33 and and 34.f The lime-
stones dip about 30, S. E. on the east side of the axis, and
*The bright golden "rosin blende" is very pure; only slight traces oi
iron and cadmium, and a small mechanical admixture of lead ; average of
14 samples: zinc, 65.9; sulphur, 32.3 ; iron, 0.8; lead, 0.3; cadmium, 0.07.
Average of a year's work showed about 18 per cent, of blende in the vein.
Run of vein one mile; another, covered with 15' soil, 1| m. further on.
reins proved to depths of 75' and 110'. North vein' worked out for 300', to
a depth of 50', with an average width of 12'. South vein worked out 400', to
a depth of 75' ; more regular ; width from 14' to 18' ; zinc in vein never ex-
ceeded 12 p. c.; richest ore from 50' down to 75' ; "at the 110' level, although
the vein is well defined, there is little or no ore in it, at any of the points
where it has been opened, and what little ore is in it appears in strings and
not disseminated as above." (For details of history, machinery, cost of
mining, manufacture of spelter, &c., see Mr. Spilsbury's letter in C3, pp.
202, 203.)
fThe axis sinks at the rate of 600' per mile from the vein at Birmingham
to the head of the Kettle; so that the zinc mines are very low down in the
magnesian limestones of II.
ZINC MINES IN NO. II. 445
about 80 E. S. E. (overturned), on its west side. The
Keystone Zinc Co.'s mine near Mr. Kinch's house, and the
deep shaft on the Borie farm are both near the axis.
Fissure veins occur in various parts of the valley, and
were tried for as long ago as the War of Independence, as
the old pits on the Fleck farm bear witness.* But most of
the work has been done by the Keystone Zinc Co., which
was incorporated in 1864, and abandoned mining in 1870. In
1875 the Tathams tried to find good working ore with a deep
diamond drill hole east of the Fleck farm. In 1876 W.
Arms tried to develop a vein on the Isett farm. Still later
prospecting has been done, and the citizens of that district
are subject to periodical excitements by vague or incorrect
reports of mineral wealth hitherto concealed, or "never
properly developed," as the favorite phrase is worded. But
certainly enough has been done to disprove the probability
of extensive deposits underground, and to sustain the geo-
logical theory that the metals were originally distributed
through the limestone strata, set free by erosion, and con-
centrated in small quantities in fissures.
It is impossible to examine the closed up and decayed
workings ; but much can be learned from the reports of ex-
perts like Dr. Roepper of Bethlehem ; Mr. Williams of
Philadelphia ; Mr. IHckerson, Mr. Spilsbury and others.f
The Keystone Zinc Co.'s shafts, about \ m. S. W. of Bir-
mingham, were sunk from the top of a knoll 80' above the
road, and drained by an adit level, driven on 347' S. W.
One line of shafts followed the limestone strike on a vein
so variable as to open out into spacious chambers, and con-
tracting again to a mere crack. This fact alone suffices to
stamp the " vein " as no true vein, but a cavern deposit, like
any limonite bed. Were there a true vein it might be
traced to the river and be found in the bank ; but no trace
of ore has rewarded diligent search in that direction, and
*SeeGen. Roberdean's letter to President Reed, dated April 17, 1778, in
Pennsylvania Archives, Vol. 6, p. 422. Smelted lead was sent down the
river in flat boats. Another attempt was made by John Musser <fe Robert
Morris in 1795, the probable date of the old tunnel on the Keystone Zinc
o.'sland.
t Mr. Platt had access to these reports, most of them in manuscript.
446 GEOLOGICAL SURVEY OF PENNSYLVANIA.
no success has rewarded equally diligent research in the
other direction, south west ward.*
The zinc blende and. galena are combined in compact, fine-
grained, dark (waxy when broken) lumps, some as large as
a man's head. The sulphide of lead is always present, but
always subordinate to the sulphide of zinc ; there is usually
a little calamine (hydrous silicate of zinc) ; and the gangue
is inconsiderable, consisting of magnesian limestone and a
little iron py rites, f
At the southwest end of the valley, therefore in the
upper limestones of II, the zinc-lead deposits differ from
those near Birmingham. Here the fissures run transverse
to the strike of the limestones, are nearly vertical, and few
of them more than 6 inches wide. Frequently, but not
always, a thin coating of heavy spar (sulpJiate of baryta)
separates the ore from the limestone walls ; and much heavy
spar is associated with the blende and galena in the gangue
stuff.:}:
*It must be said that no continuous trench along the outcrop of the sup-
posed vein was ever made ; and its alleged continuity was considered to be
proved by a gangway 166' long, connecting two shafts below. More than
2000 tons were won from the shafts ; one yielding very lean ore, the others
very rich ore. What remains unsmeltea at the abandoned works at Bir-
mingham is ore of even quality, analyzing up to a maximum of 30 per cent
metallic zinc.
f Analysis by McCreath : Sulp. lead, 18.37 ; sulp. zinc, 76.98 ; ox. iron and
alum., 1.90; carb. lime, 0.05; carb. mag., 0.17 ; water, 0.27; silica, 1.67 ; that
is lead 15.91 ; zinc 51.63. Another specimen yields lead, 5.86 ; zinc, 30.40.
For Mr. Williams' description of the seven shafts and workings, see T, p.
258, etc. He says that shafts 5, 6, 7 had been (Nov., 1865) carried down
through a heavy mass of ore and connected by a 165' long drift all in the
same mass, with an average thickness of 7'; quality excellent. He esti-
mated that there had been an output of 1300 tons of rock ore (30 p. c.) and
2000 tons of "wash or earthy" ore (8 p. c.). He remarks that the dolomite
wall rock was singularly tree from impregnate particles of blende or galena ;
one specimen analyzing carb. lime, 53.9 ; carb. mag., 41.3. But Platt re-
marks that there was abundant evidence that thin streaks and threads of
both ores do occur in the dolomite rocks. On the Kinch farm, directly oppo-
site the company's adit, runs a sandy limestone, through which much galena,
blende and calamine are scattered but too sparingly to make the rock an
ore (T, p. 262). This outcrop is continuous for a long distance without
changing its character. The presence of calamine shows that the sulphides
have been reached and converted by percolating waters.
{See description and analysis in T, pp. 263, 264. The pits on the McMullen
farm, are close to the edge of the slate belt, No. III. The Kryder pits are
ZINC MINES IN NO. II. 447
All that lias been said above proves that these zinc-lead
veins are precipitation deposits, are not connected with any
deep metallic masses in the under world, and cannot de-
scend lower than the extreme limit of rain water percola-
tion in any district of the State to which they belong. I can-
not agree with Dr. Roepper* in looking upon them as true
veins, afterwards distorted by a fault-slide pressure into
chimneys and pockets like the magnetic iron ore veins (or
beds) of northern New Jersey with which he was so well
acquainted. I consider them as of the nature of compara-
tive recent cavern and fissure deposits, scarcely at all
changed in form by later earth movements.
Barytes in II.
Barytes (sulphate of baryta} occurs rather frequently
in small pockets in the limestones of II (as well as in the
Lower Helderberg limestones of VI) usually accompanied
by small percentages of sulphate of stronlia ; but strange
not far off. The Bridenbaugh's pits and cross cuts revealed one vein 8 in.
wide with N. W.-S. E. strike, vertical and unchanged to a depth of 25', with
abundance of heavy spar. On the Raemy farm much scattered surface ore.
The Crissman pits proved three fissure veins, ono said by Mr. Dickerson to
be fifteen inches, thickening downward ; another 3 feet wide, and forking
and reuniting around a wall horse. Of these shafts Mr. Williams afterwards
expressed an unfavorable opinion. The Borie farm "deep shaft" (80') was
sunk on a 4-inch vein, thickening downwards to 14 inches, yielding 300 tons
and then abandoned. The Fleck farm pits showed other fissure veins, in
which the gangue is between rock walls, both of them lined with calcspar.
The Isett farm shafts are said to have been sunk on two parallel veins, each
nearly 2' wide, and striking with the country rock. (T, p. 271.)
* "The fact that the ores are mainly sulphides, and placed in rock almost
entirely unaccompanied by clay, excludes the idea of their being merely
mechanically transported into already existing cavities of the rocks. The
whole mode of occurrence contradicts such a supposition, and leads, irre-
sistibly, to the conviction that the ores were formed in the place they are now
found, by geological-chemical agencies ; that the pocket shape of the lodes
is merely the result of mechanical derangement and contortion of the hill ;
and that these pockets have been formed out of original true veins following
theoriginal N. E. and S. W. strike of the strata. Itisonly necessary to notice
the shattered condition of the rock, and to observe the contortions exhib-
ited by the section of the hill along the Pennsylvania railroad, readily to ac-
count for the transformation of regular veins into a more or less irregular
system of pockets." (Roepper.)
448 GEOLOGICAL SURVEY OF PENNSYLVANIA.
to say no trace of the latter could be found in the five analy-
ses made by McCreath (3 from II, and 2 from VI) published
in Report M2, p. 369.
In Franklin county, in the Great Valley, 2 m. S. of
Waynesboro, on Chr. Shockley's farm, it was found in
radiating columnar masses ; white to bluish white ; vitre-
ous lustre ; (Spec. 735) sul. baryta, 95.91 ; silicic acid, 2.80 ;
ox. iron and alum., 0.24 ; lime, 017 ; magnesia, 0.11 ; water,
0.09. Another, found in that vicinity, granular, also slightly
fibrous, generally very white, some stained with iron oxide,
powder white with brownish tinge ; sulp. bar., 98.05 ; sil.
acid, 1.11 ; ox. iron and al., 0. 14 ; traces of lime, mag. and
carb. acid ; water, 0.20. It has been found as white lamel-
lar barite on S. Plum's farm in Franklin county. (Genth's
Report B, p. 228. )
In Blair county at Galbraith's 2 m. S. S. W. of Birming-
ham, the analysis being quite like the last.*
In Montgomery county, at Marble Hall, a granular gray-
ish-white barife resembling marble occurs with the marble-
beds of No. II. f
That bar He must be extensively and rather abundantly
distributed through some if not all the formations of the
State is proved by Dr. Genth's analysis of that remarkable
flow of salt water from an oil boring in Elk county, called
the " East Clarion Spring Water," one gallon of which con-
tained 419 grains of matter, of which 337 were chloride of
* T, p. 246. Two other quite identical analyses of the mineral from the
lower Helderberg limestone (VI) near Fort Littleton in Fulton county, will
be given in the chapter on that formation. Barite has also been found at the
bottom of VII (Oriskany <S&) in Sandy Ridge near Orbisonia, Huntingdon
county. (Genth's B, p. 228.)
f Barium is confined to no formation, but it affects mines of limonite, and
is probably held in solution by many of our waters. Dr. Genth reports it
in very perfect transparent, greenish, tabular crystals ( in. diameter) and
clusters of bluish tabular crystals; also crested, fascicular, and radiated
crystals and crystalline masses at Perkiomen mine near Shannon ville, Mont-
gomery county. Also, fibrous with copper ore at Jug Hollow mine, Mont-
gomery county. Also, white laminated crystalline masses at Phoanixville
mines ; and in similar manner and also crystallized with copper ores, 3 m.
W. of New Hope, in Bucks county. Also, a fetid barite in brownish radiat-
ing and columnar ferruginous masses at Heidelberg, Berks county. (Re-
port B, p. 146.)
ZINC MINES IN NO. II. 449
sodium, 52 were chloride of calcium, 15 chloride of magne-
sium, 1.725 chloride of barium, and 0.128 bicarbonate of
barium*
It is very surprising that strontium should not appear
in company with barium in the limestones of II and VI.
In the East Clarion Spring water Dr. Genth only found
0.06 grains of the chloride and 0.005 grains of the bicar-
bonate of strontia. But, on the other hand, the sulphate
of strontia (celestite) makes the famous stratified bed in
Blair county, opposite Bell's Mills. f
The origin of the barite in our sedimentary rocks is an
interesting problem. The masses found are evidently seg-
regations, precipitations from water confined in cavities,
hut how localized is not understood.:}:
It is however brought into immediate relations to the
veins of zinc-lead, by the occurrence of two true veins of
sulphate of baryta (heavy spar) in the hill on the Kinch
farm in Blair county, one 6 inches and the other 3 inches
wide, separated by two feet of sandy limestone (Calcifer-
ous, Ila) dipping nearly vertical and striking N. E.-S. W.
These veins have no other material ; but some of the zinc-
lead veins have in their gangue a considerable admixture
of heavy spar. (T, p. 272.)
* He adds that this mineral water contains the largest quantity of chloride
of barium ever observed in any springs, and may become of great importance
after its medicinal properties have been more fully investigated. (Report B,
1874, p. 27.)
t It occurs here in a series of thin seams, pale green, crystallized in col-
umns of fibres, crosswise, containing strontia 42, sulp. acid 58. (Klaproth,
1797.) H. C. Lewis, however, found a white fibrous aragonite in seams
and crystalline crusts in the nearly pure limestone of the Water-lime divi-
sion of formation VI in Mifflin county, opposite Mt. Union, 2 in. E. of Ma-
tilda furnace, containing carb. strontia 0.58 ; and with this Dr. Genth found
groups of minute divergent needles of strontianite, consisting of carb. lime
15.36, carb. strontia 83.15, etc. (Report B, 1876, p. 229.)
f Dr. Genth's analysis of the green orthoclase felspar lennilite (or dela-
warite) of Delaware county, gave 0.57 baryta ; and his three analyses of
another orthoclase felspar (Lea's cassinite) from Blue Hill, Delaware
county, gave 3.79, 3.75, 3.60 baryta. The clays produced by the decomposi-
tion of such felspars must necessarily retain much barita converted into
barite.
29
450 GEOLOGICAL SURVEY Of PENNSYLVANIA..
Gypsum absent from No. II.
Plaster rock (gypsum, sulphate of lime} does not occur
in formation II in Pennsylvania. In fact even as isolated
crystals it is extremely rare in the State, and is only seen
where the water from oxydized pyrites acts on the lime-
stone beds, as at Van Arsdale's quarry near Feisterville,
Bucks county, producing beautiful slender crystals, some-
times 2 in. long and in. wide, or much smaller as at Corn-
wall. Such needles frequently are seen on the magnetic
iron ore, or upon a decomposed clay-like mineral, often in-
termixed with arborescent copper. (Genth in B, p. 148.)
The so called "Plaster rock" of the Wilsham quarry in
Nippenose valley on the Clinton county line, ground at
Metzger's and other plaster mills near by, and sold as plaster
at prices little below Cayuga or Nova Scotia plaster, was
found by McCreath, at the Survey Laboratory in Harris-
burg, to be a nearly pure limestone, with less than 1 per
cent, of gypsum in it.* The place of the beds is about
500' beneath the bottom of the slate formation No. III.
* Montreal plaster has sulp. acid 46, lime 33, water 20. The Nippenose
plaster consists of carb. lime 95.1 ; carb. magnesia 1.0 ; silica 2.7 ; sulp. lime
(gpysum) 0.7 ; carb. iron 0.3 ; carbon and water 0.2. (Report G2, p. 81.)
TRAP DYKES IN NO. II. 451
CHARTER XXXVIII.
Trap dykes in No. II.
In Berks county, a trap dyke, 4m. W. of Reading, issues
from the Trias country and cuts the limestone belt in a IS.
E. direction. Crossing the turnpike a little E. of Sinking
Springs and following down the west side of Cacoosing
creek, it makes a fine show on Tulpehocken creek near Van
Reed's mill. Its boulders appear on the slate soil further
on near Epler's ; but the dyke cannot be traced beyond
this to the Schuylkill.* It is evident that this dyke is in
some way connected with the great outbursts of trap in the
Trias south of Fritztown near the Lancaster county line ;
but the long way it runs, its straight course, and its nar-
rowness make it difficult to suppose that the crack was in-
vaded horizontally. The lava must have come from a great
depth, and therefore could have had no real connection with
the Trias. Its abundance in the Trias only goes to show
that the disturbance which produced the fractures, and the
filling of these cracks with lava, were events of a post-
triassic age. A similar occurrence on a much larger scale
in Cumberland county teaches the same lesson.
In Lebanon county a small dyke issues from the edge of
the Trias 2m. E. of Campbellstown, just west of Killingers
run and can be followed half a mile across the limestone.
But N. of Lebanon city is a much more remarkable case.
Three dykes appear between Mt. Ararat and Jonestown,
running in parallel E. and W. lines, about a mile apart ;
the middle one, about 4 miles long, reaching nearly to Mt.
Union P. O. They are in the slate belt. They do not
touch the limestone belt ; nor run ~N. and S. as if connected
with the reservoirs of trap under the Lancaster-Lebanon
* Rogers' Geol. Pa., 1858, p. 251. It has been omitted accidentally from the
Berks county map in Hand Atlas, X.
452 GEOLOGICAL SURVEY OP PENNSYLVANIA.
county line. They must certainly come up from the azoic
floor beneath the limestone which is beneath the slate ; that
means from a depth of at least a mile beneath the present
surface.*
In Montgomery county a long staight trap dyke crosses
the Schuylkill river at Conshohocken 500' N. of the bridge,
where it outcrops on the west bank in a picturesque black
wall 40' thick and as many high. It runs east and west
from the river in an almost absolutely straight line (about
N. 23 E.) eight miles, from the Chester county line a mile
W. of Mechanicsville, toFlourtown, east of which it cannot
be traced continuously, if at all, into the Trias country
towards Doylestown.f
For 2^ miles west of the Schuylkill it runs through South
Valley Hill primal slates, which stand like the dyke nearly
vertical. A mile east of the river it takes the line of contact
of slate and limestone, and keeps it two miles further to
Marble Hall ; for the next mile it runs obscurely in the
limestone ; for the next two miles it is plainly seen in the
heart of the limestone belt crossing its center line very
obliquely to Flowertown. It nowhere indicates disturb-
ance or faulting of the formations up through which it
comes from some unknown depth, where an unexplained
reservoir has furnished all the dolerite traps of the region,
for they are all alike, whether they cut gneiss, primal slate,
limestone, or Trias.:}:
* These dykes are represented cm the small colored map of Dauphin and
Lebanon, No. 22 of the Hand Atlas, Report X, as located by Mr. Sanders in
his survey of the slate belt. The presence of trap is well known to the citi-
zens of Lebanon. Whether the crushed limestone breccias of Mt Ararat
were made during the movements connected with this eruption of lava, no
doubt in Pofct-triassic times, is a mere conjecture.
| Prof. H. C. Lewis thought he could make it continuous that far. Mr. C. E.
Hall however gives on a page plate map (Fig. 4, p, 22, Report C6, 1881) a line
AB in prolongation of the dyke eastward, and another line CD, 32 off to
the north, passing through four patches of trap boulders on cross roads, and
close to a fifth at Jarrettown. Mr. B. S. Lyman's survey of the Trias belt
has taught that a connection of the Conshohoken dyke with the sporadic trap
shows of the Trias is improbable. The same may be said of its continuity
westward with the sporadic traps of ^Delaware and Chester counties.
% See Dr. F. A. Genth's analyses given in C6, pp. 94 to 99, Specs. 5063, '4,
501J6, 7, '9, 5072, 5081, '2, '4, '6, and p. 134, Spec. 7789, which last reads: Loss
TRAP DYKES IN NO. II. 453
It might be supposed that this trap dyke has had some-
thing to do with making the white marble beds at Marble
Hall, if that idea were not negatived by the fact that the
range of white marble quarries east and west of the Schuyl-
kill is quite independent of the dyke.
In Lancaster county Prof. Frazer has traced an extraor-
dinary trap dyke from the Susquehanna river 3 m. above
the Maryland State line, in a N. E. by N. nearly straight
course, past Goshen, Quarryville and May P. O., Kinter's
P. O., Boyerstown, and Springville (Salisbury P. O.), to
the Welsh Mountain 2 m. E. of Mt. Airy, a distance of 25
miles. It probably passes on five miles further concealed
beneath the primal sandstone surface rubbish of the mount-
ain land, and is seen again for 2 miles crossing the Cones-
toga valley limestone 2 m. W. of Churchtown, then losing
itself beneath the southern edge of the Trias, as if making
for the great trap outburst in Berks county on the north
edge of the Trias, S. and S. E. of Reading.
At Quarryville it cuts diagonally across the limestones
of the Chester valley ; at Kinzer's, Boyertown and Spring-
ville it cuts for 6 miles diagonally across the limestones of
Pequea valley ; at its south end it cuts diagonally across
the Peach Bottom primal slates ; and in other long
stretches of its course it cuts the Philadelphia schists.
At Springville it is either interrupted for a short dis-
tance, jogged to the east, or is duplicated, the surface being
covered with trap blocks. It branches, or is intersected
by a short dyke m. N. E. of Boyertown. Two miles S.
of Kinzer's it cuts the hornblende gangue rock of the
Gap Nickel mine ; and a small parallel dyke here runs half
a mile distant from it, a mile above Georgetown, both
changing their course locally to S. by W. Several such
local fluctuations from a perfectly straight course are
noticed before it reaches the Susquehanna at the mouth of
Peters creek. It may extend into Maryland but is not
by ignition, 6; silica, 39; alumina, 32; ferrous oxide, 9; ferric oxide, 2.2;
potassa, 5.3 ; magnesa, 3. 1 ; soda, 2 ; titanic acid, 1.2 ; phos. acid, 0.5 ; niccolous
oxide (with a trace of cobalotus oxide), 0.06.
454 GEOLOGICAL SURVEY OF PENNSYLVANIA.
traceable on the surface for six miles S. W. of Peach Bot-
tom ; then a dyke is to be seen half a mile south of the
State line, and a mile south of the roofing slate quarry
ridge.*
That the roofing slates have been produced by plutonic
action I cannot think, for those in the Lehigh country are
far removed from any such influence. It is possible that
there may be a closer connection between the dyke and the
nickel ore. The fountain seat of such a dyke must evi-
dently be at a great depth.
In York county two trap dykes cut the limestone rocks,
one four miles east of York, the other two miles west of
York. The Loganmlle dyke, about 13 miles long, runs in
a N. N. E. direction, with a deflection and a short branch
at Logansville, and a true north course from Longstown to
the Wrightsville railroad, where it seems to terminate at
the synclinal axis of the York valley limestone belt. The
Staresmlle dyke, six miles long, runs N. by E. from the
south edge of the York valley limestone belt, across the
Shortline RR. 2 m. S. W. of York to the edge of the Trias
at Staresville. If continued under the Trias 6 miles further
northward it would join the great trap outburst on the
Susquehanna between New Holland and Groldsborough. It
cuts the Codorus limestone beds its whole visible length,
and throws a short branch S. W. also in limestone. f In
this case as in that of the Conshohocken dyke no production
of white marble appears as due to igneous action.
In Cumberland county we have the most remarkable ex-
hibition of trap outside the Trias region. It is like the
Sinking Spring dyke in Berks county, but vastly larger and
*See Prof. Frazer's detailed description of this dyke in his report on Lan-
caster county, C3. p. 28 to 31 ; also the colored county map in C3 ; also
Hand Atlas, map No. 35. On page 78 it is said that the dyke was traceable
only by its boulders across Eden township. See other similar references
elsewhere in C3.
f See the colored geological map of York county in Report C2. The rep-
resentation in the Hand Atlas X, map No, 61, is not quite correct There is
a short dyke represented cutting the limestone area at the N. W. line of York
Bounty coming in from Cumberland county.
TRAP DYKES IN NO. II. 455
infinitely more instructive as to the source of the lava ; lo-
cating it in fact several miles beneath the present surface ;
for it is incredible that lava, however fluid, could flow
through a narrow crack horizontally a distance of 25 miles ;
and even if this could be done for the single dyke which
crosses the Great Valley and the Perry County Cove, it
would not generate the three other short parallel associated
dykes in Perry county which do not appear at all in the
Great Valley. Moreover the thickest part of the dyke is
in the Cove. Evidently the focus of activity must be located
under Perry county, and be in some way connected with
the faulted, overturned, profoundly deep Cove synclinal.
As the dyke cuts the slate and limestone belts of Cum-
berland county, and is probably continuous (underground)
through the South mountains into Adams county, (there
connected with the great outbursts of trap in the Trias,) we
must take it for granted that in Perry county it descends
through all the formations from XI to II, into the Cam-
brians, and through them into the floor of gneiss. There
are 19,000' of strata exhibited in Perry, and at least 6000'
more in Cumberland, making 25,000' to the bottom beds of
II ; to which must be added say 15,000' of South Mountain
Cambrian rocks. It is evident then that in Perry county
the lava has ascended from a depth of from 5 to 7 miles to
reach the present surface. How far it rose above the pres-
ent surface of the Great Valley would depend upon the pre-
cise Post-triassic age of the dyke ; for, if it reached and over-
flowed a surface already sculptured by erosion during the
whole Triassic age, all that upper part of the dyke has
been swept away, and nothing remains but its stem, from
the present surface to its roots in the deep.
The dyke is first distinctly seen at Boiling Springs on
Yellow Breeches creek. South of this its upper edge is
probably concealed beneath the deep alluvium at the foot
of the South mountains, across which it might probably be
traced, for Mr. Lehman in his topographical survey found
fragments of trap in the woods on the line of the dyke pro-
jected southward.*
*On the colored map of Cumberland county in Atlas D5, a branch dyke
is seen taking off' from near Boiling Springs and running some distances. W .
456 GEOLOGICAL SURVEY OF PENNSYLVANIA.
From Boiling Springs it runs in a slightly waving nearly
straight line N. 10 E. 10 miles to the top of the North mount-
ain 2 m. E. of Sterritt's gap. Across the limestone belt of
cleared land (here 7 miles wide) it makes a continuous ridge
about 50' high, conspicuous to travelers because left wooded
by the farmers' of the valley ; and this leafy barrier has
been adopted as a township line between S. Middleton and
Monroe, and between Middlesex and Silver Spring town-
ships. It crosses the turnpike 4 miles E. of Carlisle, and
the railroad halfway between Middlesex and Kingston
stations. The slate belt is here 3 miles wide and the dyke
upon the township line is perfectly straight ; all its devia-
tions from a straight line take place in the limestone belt,
and these deviations are undoubtedly due to the crumpled
condition of the limestone formation, although the frac-
ture was almost transverse to the general strike.
Descending the north slope of the North mountain into
Perry county it crosses Fishing Creek valley and makes the
divide which casts the water off east down Fishing Creek,
and west into Sherman creek upper branches. Keeping on
across Cove mountain and the head of Cove creek it as-
cends the slope of Peter' s mountain and is lost near the sum-
mit.* *
As the Cumberland county dyke cannot be properly un-
derstood if only studied in its course across the limestone
and slate belts of the Great Valley, I will give here Prof.
Clay pole's description of it in Perry county, and of three
*Dr. Henderson's description of it published by Prof. Rogers in Geol.
Pa. 1858, p. 366, is very erroneous, for he carries it across the Juniata and
Susquehanna rivers into Dauphin county. It is but justice to Dr. Hender-
son, who was one of the best geologists of his day, and to whom we owe our
first accurate knowledge of the complicated structure of Perry, Juniata and
Mifflin counties, to say that he could only with great difficulty at that early
day trace the line of the dyke upon his map ; and the line which he laid
down on his map was transferred to the Geological Map of Pennsylvania,
made by me in 1842, and published by Professor Rogers in the Atlas to his
Final Report, 1858. I am sorry to add that 1 embodied these errors in the
small map of Perry county, Map No. 45 of the Hand Atlas, Report X, drawn
by me in 1878, previous to Professor Claypole's elaborate survey of the
dykes, published in Report F2, 1885. The reader is therefore referred to the
second (revised and amended) colored geological map of Perry county in
that Report.
TRAP DYKES IN NO. II.
457
Tl. XXVI
Jfap dyke* m GiMnlerlanJ and Sherry cotmtieb
458 GEOLOGICAL SURVEY OF PENNSYLVANIA.
other dykes in that county which probably have an under-
connection with it at some unknown great depth beneath
the present surface.
Plate xxvi, p. 457, shows the geographical relationship
of these four Perry county dykes, named by Prof. Clay-
pole : Great Horseshoe, Little Horseshoe, West Duncannon
and East Duncannon dykes.*
(-?.) The Great Horseshoe dyke, Ironstone ridge, or Cumber-
berland Valley dyke.
The line of this dyke maybe detected by loose fragments
on the south side of Peters' mountain about two and a half
miles west of the river and between the highest terrace and
the summit of the mountain. Its course is plainly indi-
cated down the slope by the same evidence from terrace to
terrace, with a bearing of S. 10 W. into the Cove at the
foot of the Horseshoe and almost to the creek.
Along this part of its course it appears to be the widest
of all the dykes in the Cove, but just before it reaches the
creek it suddenly and markedly increases and assumes
comparatively gigantic proportions, admirably displaying
both the trap and the accompanying rocks altered by con-
tact with it. The sandy beds of the Mauch Chunk Red
shales (XI) which are here cut through are changed to a
dark brown and chocolate colored material ; the red shales
themselves are in some places burnt into a mass resembling
half made brick, but not usually much hardened. Some
fine shale beds, however, have been so much changed that
they are almost as tough and hard as the trap itself. This
change in the appearance of the rocks at this point has led
* The descriptions are in his own words, copied from his report F2, pp.
296-301. On the map I have renamed his West Duncannon the Mid Cove
dyke, which extends northward into Wheatfield township ; and I have ven-
tured to give the name Duncannon dyke to the dyke in Watts township, as
it is in line with the (East) Duncannon dyke in Penn township; and this
doubtless deceived Henderson into believing that the Cumberland county
dyke was single and 30 miles long. His belief, however, may after all be a
correct one ; for the most striking fact exhibited on the map is the N. 10 E.
direction of the Cumberland dyke, the Mid-cove dyke, and the Watts town-
ship dyke, all three on the same line, while sending off branches to the
north, as if there was but one dyke in the deep.
TRAP DYKES IN NO. II. 459
to considerable excavation in the belief that the dark, soft,
sandy shale beds contained copper a belief for which there
is of course not the slightest foundation.
The excavation serves to make very plain the striking
development of the dyke at this point. From being a dyke
very much resembling the other three perhaps rather
larger it suddenly enlarges and becomes nearly WO feet
from side to side. The bed of the Cove creek and the flat
marshy ground alongside of it, overgrown with a thicket of
laurel in some places impenetrable, is thickly bestrewn
with massive blocks of the dyke up to half a ton in weight.
How far this display continues through the wood I cannot
say nor to what height it rises on the north flank of Cove
mountain. The bearing of this dyke is S. 10 W.
The Great Horseshoe dyke passes through Rye town-
ship almost from north to south where it is well known as
the Ironstone ridge, and forms a watershed across the valley.
Coming down from nearly the top of the Cove mountain its
track may be followed by the characteristic belt of yellow
soil and heavy rounded rusty bowlders through the woods,
almost along the road (hence called the Ridge road), to the
middle of the valley. The land on both sides of it is so
encumbered with wreckage from the dyke that it is left
unfilled and uncleared. But it is at the crossing of the
main valley road that the most magnificent display of the
Great Horseshoe dyke occurs in Perry county. Here the
road for 500 feet on each side of the line is embanked with
bowlders that have been removed from the land and piled
up in grand disorder. The dyke itself does not probably
exceed 200 feet in breadth, but its fragments strewn along
both sides make it seem very much wider. North and
south of this point the exhibition is less striking but the
ridge may be traced without difficulty for nearly another
mile, when it is lost on the slope of the Blue mountains.
The nature of the trap and further details may be found in
the account of Penn township.
Traces of another (the Little Horseshoe dyke) may be
found about 500 yards to the eastward in a number of loose
blocks of trap scattered along the road, but no ridge in any
degree resembling the Great Ironstone ridge can be seen.
460 GEOLOGICAL SURVEY OF PENNSYLVANIA.
(0.) The Little Horseshoe dyke.
About a quarter of a mile east of the Great Horseshoe
dyke, another parallel line of fragments can be found high
up the south slope of Peters' mountain, in fact upon the
highest terrace. Its first appearance, so far as I am aware,
is at an old shaft sunk some years ago under the impression
that the trap dyke carried an ore vein. The shaft was sunk
to a depth of about 25 feet, and at the depth of about 22
feet many blocks of the hard tough dolerite (trap rock)
were thrown out. This is the most northerly indication of
this dyke that I have seen in the cove. Hence, it may be
followed at intervals southward down the slope of Peters'
mountain, forming an almost continuous line through the
thickets to the cleared land in the cove below, where it
crosses first a field and then the road leading west into the
woods of the Horseshoe, and is lost to view at the creek,
where a large meadow is almost ruined by the number of
blocks which lie scattered about upon it. Beyond the creek
no one, so far as I can learn, has succeeded in tracing it, so
that it probably does not rise so high on the Cove mountain
as it does on Peters' mountain.
I have no means of estimating the breadth of the dyke
but judge it not to exceed 6 or 8 feet. Its bearing is, as
nearly as I could ascertain it, south 10 west.
Its southward prolongation into Rye township is only
attested by a number of loose blocks scattered along the
road about 500 yards east of the Great Horseshoe (Cumber-
land Valley) dyke ; but no ridge is made by it in the topog-
raphy of the surface.
The Mid Cove or W. Duncarinon dyke.
Half way between the head of the cove and the river, and
near the foot of Peters' mountain, a range of trap can be
readily traced It crosses Cove creek close by an old saw-
mill pond, now dry, and then shows in a byway on the
north side of the main turnpike road. Following it over a
field it is seen very plainly in the bank, and then runs along
keeping parallel with the same road as far as the foot of the
TRAP DYKES IN NO. II. 461
Cove mountain. In front of the farm-house which stands
at this point is a well sunk exactly on the line of the dyke.
Mr. J. M. White who sank this well informed me that he
passed through the dyke, and that it is not vertica , but
pitches to the west at an angle of about 45. The greater
part of the well was sunk in the red shale, the dyke being
left at a depth of about 8 feet. It measures here only
about 6 or 8 feet, and consists of a number of loose blocks
embedded in the red clay the product of their own decom-
position. In the neighboring field a pit was dug to examine
the dyke, which gave the same results. Crossing the road
at this point the dyke can be traced about 100 yards further
through the orchard into the wood, where all traces of it
are lost, nor has any one, to my knowledge, ever seen it
higher on the hill.
It has not been seen in Fishing creek, in Rye township ;
nor in Cumberland county.
But it extends northwards from Peters' mountain into
Wheatfield township, crossing Sherman's creek and the
Little Juniata a quarter of a mile only from the river at
Duncannon. A mile N. of Duncannon it bends and takes
a nearly due N. course to the turnpike a mile S. of Losh's
Run station on the P. RR., beyond which it is not seen.*
(4) The (East) Duncannon dyke.
About three quarters of a mile further east a trap dyke
may be seen in the roadside about \ mile south of the mouth
*I give Prof. Claypole's detailed account of this part of it, beginning at
the north and going south : Its first appearance is on the turnpike road
about one mile S. of Losh's Run station, P. RR. Its next appearance, so
far as I am aware, is on the road leading west from the Aqueduct. There is
no trouble in following it from this point by an almost uninterrupted series
of exposures to Duncannon. Its course is marked by the red color of the
soil, for a mile due south, across fields, to the road running west from the
railway station at Juniata bridge. Here a pit was sunk some years ago in
quest of ore on the western edge, of the dyke, to a depth of about 25 feet. A
drift was then run for 6 feet into it in the attempt to penetrate it. This made,
its thickness upwards of twelve feet. The same discolored sandy shales
were thrown out here as in the Cove.
At this point the direction of the dyke suddenly changes ; but a thin vein
of trap appears to continue nearly on its former course, as indicated by an
occasional trap pebble in the low ground. Such pebbles have been found in
462 GEOLOGICAL SURVEY OF PENNSYLVANIA.
of Sherman's creek. Thence it has been traced up the hill-
side, where its outcrop has been followed, in a vain search
for iron ore, to the top, but not to the crest of Peters'
mountain. The dyke cuts through it near the brow over-
looking the river. It continues on the same course, S. 20 W.
down the south slope of Peters' mountain into the Cove, and
may be followed by the color of the soil and the loose blocks
lying about across the fields to the main road up the Cove,
which road it crosses just east of a farm-house. Running
on thence with the same bearing, it may be seen alongside
of the road (which here turns to the south-southwest) for
about 200 yards, where it crosses a lane running off at the
next angle in the road. Here its presence is marked by the
usual red clay and bowlders. Beyond this point southward
I have not traced it.
In Watts township between the Juniata and Susquehanna
rivers may be found a dyke which is probably a continua-
tion of this Duncannon dyke as it is in almost exactly the
same line, but the interval (from Duncannon to the N. W.
point of Duncan's island) is 3% miles, no great distance for
an underground connection.
It appears about m. N. of Dr. Reutter's house at the
Junction, and is traceable by loose blocks 3 miles N. 10
B. nearly to the foot of Half Falls mountain.* It precisely
the run close by the place where the change occurs, near the grist mill west
of Duncannon, and again at a short distance behind the nail factory. These
are sufficient to indicate a faint continuation of the dyke in its former direc-
tion as far as to the north foot of Peters' mountain. An examination of the
map will show that it is on the line of dyke No. 3 in the Cove before de-
scribed.
But the main mass of the dyke suddenly bears away at S. 30 E. down a
slope, across a field, passing under a house (as shown when the cellar was
dug) and so reaching the river. It has not been seen in the bed of the river ;
but on the opposite or eastern river bank, opposite the mouth of Sherman's
creek, and exactly on the right course, what is probably the same dyke is
displayed in a cutting of the North Central railway.
This exposure gives an opportunity of measuring the thickness of the dyke,
which is about 50 feet. It does not appear to rise to the surface ; and the
rocks on both sides are altered as in the case of the Great Horseshoe dyke in
the cove.
*" Had time allowed might have been followed further. The last trace
of it seen was near the house of Mr. M. Peters." F2, p. 385.
TRAP DYKES IN NO. II. 463
resembles the Cove traps, a hard, tough, dark green, almost
black dolerite, containing a small proportion of magnetic
oxide of iron, rusting yellow outside, f
The most remarkable thing about these dykes is this :
not one of them lias ever been detected at the top of either
of the two mountains ; the East Duncannon and Great
Horseshoe dykes alone rising above the highest terrace, so
far as known. The West Duncannon dyke does not ap-
pear to rise into the mountain at all, its exposure ceasing
sharply at the foot. It is not, however, impossible that
further examination may modify this assertion which is
based on negative evidence only. Not one of these dykes is
yet known to appear upon the very summit of either Peters'
or Cove mountain. The Great Horseshoe dyke ranges high-
est, running, as has been shown, up to the topmost terrace
of Peters' mountain on its southern flank. This failure of
the dykes to appear at the summit proves the moiintains to
be older than the dykes. Now since the Triassic red sand-
stone of York county is cut by numerous similar dykes
with which these Perry county dykes seem to be con-
nected, they must be not only later than the coal measures,
but of later age than the Trias ; but as no such dykes are
known in the Cretaceous beds of the Atlantic seaboard,
our dykes must be older than the Cretaceous age.
f The trap of Perry county is a hard, very tough, dark, heavy and fine-
grained dolerite containing grains of magnetic iron ore disseminated through
the mass, readily discoverable by crushing a small piece with the hammer
and applying a magnet, when the magnetite immediately clings to it The
presence of this material is partly the cause of the decay which takes place
at the surface of the trap. Under the action of moisture the magnetite be-
comes rusty and passes into brown hematite. The outer layer of stone is
softened and changes color to a rusty yellow. This outside layer scales off
and the process is repeated upon the new surface thus exposed. In this way
from year to year a red clay soil is produced by the disintegration of the
other materials of the rock, felspar and hornblende, colored by the iron
oxide. In consequence of the abundance of this red clay along the course
of the trap it is usually called by the residents of the neighborhood "iron
ore," or " magnetic ore rock. " But it is not likely that any merchantable iron
ore will be found along the lines of these dykes. It. is often a task of great
labor to dig out and carry away the fragments from the fields and pile them
up at the roadsides where their subangular form and rusty color make them
conspicuous objects to the passer-by. They all consist of the same tough
hard dolerite, showing some but very little variation in composition and
fineness at different places.
464 GEOLOGICAL SURVEY OF PENNSYLVANIA.
Effects of trap.
The alteration of the magnesian limestone rocks noar the
trap dykes of Berks county is ascribed by Dr. Genth to the
infiltration of siliceous waters.*
Deweylite and serpentine are formed out of the magne-
sium carbonate.
Another portion of the magnesia separates as brucite.
The calcium carbonate crystallizes in small acicular crys-
tals and radiating columnar masses of aragonite; and also
in crystals and coarse granular masses of calcite.
The alteration of dolomite at Fritz's island has produced,
directly or indirectly, not only serpentine and deweylite,
but also grossular, a beautiful yellow and orange vesum-
anite, apophyllite, chabasite, gismondite (?), thomsonile,
mesolite, stilbite, datolite, etc.
Serpentine in No. 11.
The limestone No. II near Reading is described by Dr.
Genth as "granular, largely altered (by silicious waters)
into serpentine" \ and coated with colorless, pearly 'brucite.\
The brucite occurs also in brownish yellow thin seams.
Deweylite, white, yellowish, brownish, amorphous, also
occurs in round grains, stalactites, botryoidal, plates, slabs
(occasionally more than I") and irregular coatings. The
slabs are often arranged in layers, white and brown, often
intimately mixed with aragonite, which sometimes sepa-
rates in radiating columns or masses (50mm long) ; the
layers often separate easily, and the separation planes are
covered with small brilliant aragonite crystals. The ara-
gonite has often changed to deweylite.
The change from dolomite limestone to serpentine can be
observed in all its stages from pure dolomite to pure ser-
*At Fritz's island ; and at Wheatfleld & Ruth's mines, 2 miles E. of Fritz-
town, and 2 m. S. of Sinking spring. Proc. Ainer. Soc. Phila. Oct. 2, 1885.
See also descriptions by E. F. Smith, D. B. Brunner and I. Schoenfeld.
f Amer. Phil. Soc. Proc., Phila., Oct. 2, 1885.
fE. F. Smith's analysis of it (in Amer. Chem. Jour., V. 281) is silica
82.52; magnesium oxide, 66.78; ferric oxide, 0.44.
Analysis by H. F. Keller, silicic oxide, 39.32; magnesium oxide, 41.14;
lerrous oxide, 0.51 ; water, 18.41.
TRAP DYKES IN NO. II. 465
pentine ; which is generally a greenish yellow, greenish
white, or yellow, but also sometimes brownish and grayish.*
Aragonite and calcite are frequently associated. Magne-
tite is occasionally disseminated in fine grains through the
mass.
Olivine. Dr. Genth alludes to Dr. Wadsworth's theory
that the Fritztown serpentine is an altered olivine, and to
his assertion that the specimens show unaltered olivine^
and says : "I cannot imagine how olivine could be present
in this rock, and what it is which he (Dr. Wadsworth) has
taken for that mineral. As the trap is of triassic or post
triassic age, it is impossible for olivine or any other kind of
volcanic ash, to get admittance into the Siluro-Cambrian
dolomite strata around Reading."
* Analysis by H. F. Keller. Ruth's mine : Sil. ox., 42. 14 ; mag. ox., 41.61 ;
ferrous ox., 2.06; water, 14.20. Wheatfield mine: sil. ox., 41.46; mag. ox.,
44.68; F. ox., 0.99; water, 14.07.
f Lithological studies, by M. E. Wadsworth, Cambridge, 1884, p. 152.
30
466
GEOLOGICAL SURVEY OF PENNSYLVANIA.
Jfo. II a, GatetfarouA; 1), Cha%y; c, Jrenton Uuw,
JYfr. Ilia, ^UJicti ; '!), "Xuclfarri river slafo.
3o Musk-ale Chapter WWII.
Section fromSalilEtitjIcM'". Uirough tfw
XrrttoitcZineMinc.
Section alony l/ie Anticlinal Axis.
measures to lite south.
Mit^of Ckufer Valley.
WHITE LIMESTONES AND MARBLES OP NO. II. 467
CHAPTER XXXIX.
Wli'de Limestones and Marbles of J\o. 77, in CJtester y
Montgomery, York and Centre counties.
The white marble door and window caps and sills and
the blue-streaked marble front door steps of Philadelphia
were obtained from numerous quarries wrought along the
southern edge of the Chester County valley, east and west
of the Schuylkill river, until about fifty years ago, when
the marble quarries of Vermont began their successful com-
petition for the market. Stephen Girard built the beauti-
ful Corinthian fagade of his banking house in Third street
of native white marble. The United States Bank in Chest-
nut street, * with its severely beautiful Doric porticos, was
built of the same material, now rendered doubly pleasing
to the artist's eye by reason of the warm mellow yellowish
tint which time has given to it, and which the Greeks de-
lighted in. One side of the superb Corinthian peristyle
and cella wall of the Girard College was also built of it,
the other side and the front and rear porticos being from
the Vermont quarries, f
One reason for the gradual substitution of Vermont for
Chester Valley white marble was the great expense of quar-
rying in the Chester valley, and the cheapness of freight
by water from Vermont, as well as the singular develop-
ment of better methods of getting out the stone there ; but
there was another pregnant reason. The Pennsylvania
white marble beds are locally half or wholly spoiled by
pyrites, which runs in streaks through them and subject
* Now the U. S. Custom House.
t Its 57' high columns, built up of drums 6' long, compare favorably with
those of the Madelaine in Paris, built up of drums only about 1' long,
although the College columns are spaced so much further apart as to make
them look too slender; and the close-set double row of the Madelaine gives
to that splendid monument something of the Doric majesty of the Parthenon,
which it resembles also in its great length of side colonnades.
468 GEOLOGICAL SURVEY OF PENNSYLVANIA.
them to a slow decay. The front columns of the Custom
House, exposed to the northeast storms in cold weather,
became gradually dilapidated, and are now patched with
pieces of new marble let into the decayed places ; and such
periodical restorations will always be necessary.*
The marble quarries of the Chester valley, both east and
west of the Schuylkill, were opened along the vertical beds
next to the South Valley Hill, and the marble quality is
evidently due to the same cause to which the verticality of
the beds is due, namely, a great pressure from the south
crushing the rocks and permitting infiltration and recrys-
tallization. f
* What the streaks of pyrites do to this marble under the action of the
acids in the air, and of the frost, similar streaks of feldspar do to the syenite
obelisks of Egypt under the sand blast of the Khamzin or desert wind of
March and April.
f " It is worthy of remark, that all the marble of the limestone basin of
Montgomery county is confined to the synclinal trough adjoining the anti-
clinal axis now described, upon the N.; the.genuine marble not extending
more than half a mile from the uplifted belt of slate, nor eastward in its line
of strike beyond the neighborhood ot the point of sinking down of the Primal
slates, or past the meridian where the anticlinal rapidly loses its force. As
the marble is evidenly only a highly metamorphic variety of the ordinary
magnesian limestone, crystallized and changed in tint by igneous action
from within the earth, it is quite natural that it should run thus parallel
with and adjacent to this line of uplift, produced as this has been by the pro-
truding forces of the interior. The whole of this belt of marble is in fact but
the vertically upturned, and occasionally inverted, Northern side of this
anticlinal wave, the side along which the maximum amount of igneous in-
fluence is invariably manifested. In offering this explanation of the origin
of the marble by metamorphism, it is proper to observe that we must not
ascribe the whole of the change to its proximity to the line of anticlinal up-
lift of the Conshohocken axis. There is a tendency in the whole of the lime-
stone 01 the Southern half of the general valley to a much greater degree of
alteration than belongs to the same rocks in the Northern half. Through-
out this entire synclinal belt the metamorphism from heat, of course, has
been far greater along its Southern than upon its Northern margin, partly
because the strata of the former side'are nearer the principal injections of
igneous rocks of the whole region, and partly in consequence of the perpen-
dicular or even inverted position which has permitted the subterranean
-volcanic vapors to pervade them more freely and exert their maximum in-
fluence." H. D. Rogers in Geo. Pa., 1858, Vol. 1, p. 163.
West of the Schuylkill, Prof. Rogers remarks :" Throughout the north-
ern half of the basin, especially where the limestone observes its usually
very regular southward dip of seldom more than 45, the rock is in the con-
dition of a sub-crystalline, and even earthy or purely sedimentary mag-
jiesian limestone, and its bedding is for the most part very uniform and
WHITE LIMESTONES AND MARBLES OF NO. II. 469
In New Jersey, Sussex county, two limestone formations
surround the Franklin zinc mine, one blue and the other
rather thick. Its color is a pale grayish blue, except in neighborhoods like
that on the Schuylkill below Norristown, where a partial metamorphism
has approached the northern border, and it is then, very frequently, a pale
straw-yellow and bluish-white. The interleaved thin layers of argillaceous
matter which so frequently separate the beds of the limestone are in the
condition of an indurated clay-slate, but seldom show even incipient crys-
tallization. In many instances wide bands of the limestone, along its
northern outcrop, exhibit numerous cross-joints intersecting the beds in
nearly all directions and causing the rock in certain quarries to break into
a mere rubble of small angular fragments, assisting much the labors of the
quarryman and Hmeburner ; but these joints, and the before-mentioned
semi-crystalline texture, are the limits to which the metamorphism of the
rock has reached, a true parallel slaty cleavage being seldom or never dis-
cernible.
" But the state in which the very same beds exist, where they rise per-
pendicularly or with inversion to their southern outcrop after passing the
synclinal turn in the center of the basin, is very different from all this, and
in striking contrast The faintly crystalline and earthy limestone is here a
distinctly crystallized, often a granular marble. Its color is changed to a
brilliant white, or to a mottling of purely white and dark blue, from the
presence of segregated or half-developed graphite; and the dispersed fer-
ruginous matter is here in a state of minute solitary crystals of sulphurate
of iron disseminated through the body of stone. The rock, instead of lying
in thick, often massive beds, is cleft into thin plates by innumerable natural
fissures or cleavage-planes, not parallel with the stratification, but dipping
steeply southward or acutely across it, and these fissures are filled and
lined with distinctly crystalline flaky talcose and micaceous matter, some-
times talc and mica fully developed. The partings of slate between the lime-
stone layers have been converted to laminae of talc-slate, in which there is
often a cleavage-structure distinctly discernible, much more intimate than
that in the altered limestone, but dipping in parallelism with it Viewed
edgewise, a fresh exposure of the most altered limestone, such as is visible
on the River Schuylkill near Conshohocken, has the aspect of a blue and
mottled marble, streaked with films of talc, and shivered by innumerable
cleavage-joints; but viewed face-wise, the layers and fragments have the as-
pect ot a talcose or micaceous slate, so copious is the covering of talc and
mica upon their surfaces." H. D. Rogers, Geol. Pa., p. 213.
"The portion of the formation which enters Abington township is more
slaty and fractured than that further to the W., and it also contains a larger
amount of silicious or sandy matter. Those portions of the rock which are
exposed, or are nearest to the surface, have in many places undergone partial
decomposition, and have the appearance of a white calcareous sand. This
sandy aspect of the limestones may be observed in all the quarries in the
neighborhood of Sandy Run, and also at many other localities. Unless the rock
has undergone partial decomposition, the limestone is crystalline and granu-
lar. It varies in color from blue to white, as a greater or less amount of carbon-
aceous matter chances to enter into its composition. Each of these colors is
not confined to a particular stratum, but changes repeatedly in the same
470 GEOLOGICAL SURVEY OF PENNSYLVANIA.
white. They were supposed to belong to one formation,
one part of which had been subjected to some influence,
beds; and, indeed, the area occupied by one particular color is usually very
small. The dip throughout the whole formation is remarkably uniform.
Near Sandy Run it is towards the S. and S.S.E. Quarries and pits have
been opened on almost every farm along Sandy Run. One of the largest in
this vicinity is on the farm of Mr. Fitzwater, near Fitzwatertown. The lime-
stone is chiefly blue, the dip S.S.E., at an angle of about 60.
" On the turnpike opposite Sellerstown, a limestone quarry of some size is
wrought, the rock making an excellent lime. An extensive quarry of the
same nearly white variety of the limestone exists on Mather's farm. There
the beds are crossed by very regular joints, giving the appearance of a stra-
tification in another direction; the true dip is towards the S. Near the Ger-
mantown turnpike, about a fourth of a mile above the Plymouth Meeting-
house, are good limestone quarries. Much of the stone in this neighbor-
hood is beautifully white, though some layers occur having a more or less
bluish tint. The weathered surface of many bods is rough and sandy, show-
ing some silicious matter in the rock.
" Spring Mill. North of the Furnace 200 yards there is a large quarry in
the limestone near the southern edge of the formation, in which the dip is
85 to S. 10 E. The southern side of the quarry is massive and jointedi
and the dip planes are almost effaced; the northern side is more thin-bedded
and talcose, of a bluish white color, and its structure very crystalline.
"In that portion of the Limestone Valley which occupies the southern
part of Upper Merion township, especially in the immediate vicinity of the
Schuylkill, there are numerous and extensive quarries, furnishing a large
supply of the rock, a portion of which is transported to Philadelphia, and
other places, by the several railroads and the Schulkill navigation; but a
large amount is converted into lime on the spot, designed lor the same
markets.
" A large quarry of limestone is wrought on the west side of the Schuyl-
kill, two or three miles below Valley Forge, where the rock is tolerably
thick-bedded, and of a light color. The quarried stone is conveyed to the
river by a railroad, and thence taken by boats to the various limekilns.
Extensive quarries have also been opened near the Valley Church, where
the limestone is very similar to that of the last locality, dipping steeply
south, being of a light tint, and furnishing an excellent lime. On the road
from Glassley to Valley Forge, near the county line, there is a small bed of
slaty talcose calcareous rock extending E. and W. about three furlongs in
length towards Valley Creek. It constitutes a small hill, over the east end
of which the road passes. Near Valley Forge occurs a stratum of felspathic
rock like that seen at Barren Hill. It is exposed in the creek, and occasion-
ally appears overlying the Primal white sandstone at the foot of the North
Valley Hill, a little East of the North Valley Church. The limestone near
the White Horse Tavern in East Whiteland township is occasionally talcose
and slaty. Near the Steamboat Tavern the more usual granular structure
prevails: throughout all this range, however, the rock yields an excellent
lime.
"At Downingtown the limestone is chiefly of a light color, and compact.
Several quarries of compact and granular limestone have been opened in
WHITE LIMESTONES AND MARBLES OF NO. II. 471
heat perhaps, or pressure, which had whitened it. But in
1863 Prof. Cook showed that the blue limestone beds, dip-
tbis vicinity. The width of the formation near the East Cain Church is re-
duced to about three-fourths of a mile. It is somewhat variable, being de-
pendent, probably, upon the angle of the dip, which, however, is pretty con-
stant. At Coatesville it does not exceed three furlongs. At Bell's Quarry,
Midway, the rock is of a light color. About one mile east of Trueman'g
Mill, we find a small bed of white clay, derived from the decomposition of
an altered felspathic slate, lying between the limestone and the talc slates.
In the vicinit}' of Buck's RunandParkesburg the limestone becomes darker
and more slaty. Passing Cloud's Mill into Lancaster county, it gradually
declines in thickness, beingat Cooper's Fulling Mill, in Strasburg township,
not more than two furlongs wide. At its termination in Bart township it
becomes more than usually sandy, especially near its margin. The main
belt seems to terminate on Eckman's Run but another small lenticular belt
shows itself a mile and a half further to the west, on the promises of Mrs.
Bare, where the rock is quarried." Geol. Pa., 1858, Vol I, p. 214.
In Montgomery county: "The quarrying of marble in this district was
commenced about 75 years ago, by Daniel Hitner. For the last 15 or 16 years
the average quantity sent from the quarries of Marble Hall, owned and
wrought by the present proprietor, Daniel O. Hitner, has been about 25,000
cubic feet
The belt of marble is nearly three-fourths of a mile. wide. Marble Hall,
on the Perkiomen Turnpike, is the easternmost point at which good build-
ing marble is wrought, though the belt is known to continue further. It
extends thence to the Schuylkill nearly to the Chester county line.
The largest quarry of all is that of Marble Hall ; here the strata dip to S. 20,
E. about 85, presenting in one or two places a flatter inclination. This
quarry is not less than some 400 feet in length, and at the top is 60 or 70 feet
wide. The greatest depth to which the quarry has been sunk is 265 feet.
At this depth were procured the blocks of beautiful white marble sent by
direction of the State of Pennsylvania, and by the city of Philadelphia, to the
great monumentat Washington. At this depth the stratum of white marble*
for which this quarry is chiefly wrought, has a thickness of 5 feet; but the
usual thickness of this bed of pure white stone is 8 feet, that of the pure and
clouded white together being generally about 20 feet. Mr. Hitner has quarried
blocks 6 feet in thickness, though the general thickness of the blocks readily
procurable does not exceed 2i feet. The only saccharoidal or statuary marble
in this or any of the quarries, is found here at a depth of 120 feet, in a layer
of only 6 inches in thickness. It is of a yellowish white color and remark-
able eveness of grain. The white marble is used for monuments, and for
the finer architectural purposes. It now sells for about one dollar per cubic
foot.
To the south of the large quarry of Marble Hall, which besides the white
marble, yields much beautiful clouded or shaded stone, there is a quarry of
blue and black marble, distant about 300 yards. This owned by Mr. Lentz,
but now wrought by Daniel O. Hitner. This blue and black marble now
sells for about 40 cents per cubic foot. It is used chiefly for 4 ronts of build-
ings, for monument bases, etc. The thickness of the good blue marble in
this quarry is 22 leet, and that of the black variety 8 feet.
472 GEOLOGICAL SURVEY OF PENNSYLVANIA.
, <Stcld mf of lit
f/ntiii reyiani afCfiuta- Co.
fftotoyual ittof, of Penjurfmjua,,
(puaMedi'n ISM)
fa iJtiutraU tie jtruc&tral theory
WHITE LIMESTONES AND MARBLES OF NO. II. 473
ping northwestward, lie upon the upturned nearly vertical
southeast-dipping white limestone beds.*
In York county, Pennsylvania, Prof. Frazer was tempted
to make the same distinction in age between the white and
blue limestones of the Codorus valley. f
Besides these quarries in the vicinity of Marble Hall, there are others about
three-fourths of a mile north from Spring Mill ; one set owned by Robert
T. Potts, another adjoining his by Mr. Peter Fritz. The marble of Potts'
quarry is chiefly of the clouded variety, besides alittle white and some plain
blue. The annual yield of this quarry is about 12,000cubic feet. The quarry
owned by Fritz is at present but little wrought. Next in position to the west-
ward, but still seated in the same belt, are two quarries westward of the
Schuylkill ; these are Henderson's and Brook's, in Upper Merion township.
Henderson's the nearest to the Schuylkill, affords a plain blue marble, be-
sides a little white. Both of these quarries are wrought at present to only
a moderate extent.
A little south of the Valley turnpike, about three and a half miles E. of
Downingtown, is the extensive quarry of superior white marble which has
for many years supplied Philadelphia with the beautiful article employed
in so many of its public and private edifices. It is on the farm of Mr. John
R. Thomas. The beds on this quarry are slightly contorted. The portion
worked for the marble separates into two bauds. The rock occurs in massive
beds, chiefly white, with sometimes a bluish tinge, and is quarried with
great facility. It has been much used in the construction of the Girard Col-
lege and other public buildings which adorn Philadelphia and the neighbor-
ing towns. This marble is converted into a good lime, but its crystalline or
granular structure causes it to crumble in the kiln, making it a little difficult
to manage. The lime from this variety is much esteemed by masons, being
sold in Philadelphia under the name of Fish-egg lime.
The blue-mottled limestone or marble of Whitemarsh, occurring at the
quarries not more than three-fourths of a mile north of the northern limit
of the Primal Strata, is evidently on the south side of the trough, or folded
synclinal axis of the 'district. This is further proved by its great steepness of
dip, about 80. Tt is, moreover, of the maximum degree of metamorphism
or crystallization ; contains talcose or micaceous laminae, and crystals of sul-
phuret of iron, etc.
Strontia. Near Mr. Hitner's House, Marble Hall, there occurs a thin bed
of very ponderous rock, resembling closely a white crystalline marble. It
contains however, but a moderate proportion of carbonate of lime, and con-
sists chiefly of the carbonate of strontia." Geol. Pa. 1858, vol. 1, p. 215.
* Annual Report of 1863, p. 7. In the course of my private survey of the
Franklin mines twenty years ago, I mapped the locality, observed this non-
conformability, and arrived at the same conclusion, viz : That the two
formations were of very different ages, the white much older than the blue ;
the zinc deposits being in the white.
t See Report CC, page 132-3. Dr. Frazer says: "In Detweiler's quarry,
which is a little more than half a mile north of the Columbia bridge [in York
county] there exists a conglomerate consisting of a blue limestone holding
rounded pebbles of white limestone within it The limestone exposed
474 GEOLOGICAL SURVEY OF PENNSYLVANIA.
In the Chester county valley, no such time distinction
has ever been suggested between the blue limestone beds
of the north side and middle of the valley, and the white
marble beds of the south side of the valley; although the
dip of the former is moderately southward, while that of the
latter is nearly vertical. For, on both theories of structure,
the synclinal and the monoclinal, no such distinction was
necessary. In fact, on the synclinal theory the blue beds
turn up as white beds; while on the monoclinal theory the
blue beds, instead of overlying, underlie the white beds.
But if it could be proven the white beds at Franklin arid at
York be the oldest, then we must suppose a fault to run
through the Chester valley just north of the marble quarries.
This is possible, but not demonstrable ; nor is it a probable
supposition since it ignores the Chiques rock; and we have
no place in the Cambrian into which to put the marbles.
Since the death of mv lamented friend, the State Geologist
of New Jersey, an important report of recent surveys in
the white and blue limestone valleys of northern New
Jersey, made by Mr. Frank L. Nason, Assistant Geologist,
has been published in the N. J. Annual Report for 1890,
under the title: " The post archcean age of the white lime-
stones of Sussex county. N. /.," in which the reader will
find a large array of facts, evidently observed with great
care, skilfully correlated, and ably discussed, and the con-
clusion arrived at that there is no geological time distinc-
tion between the white and blue limestones; that they are
of the same age, belong to the same formation, and are in
fact merely the same beds in different conditions; that they
can be traced along their outcrops so as to be observed to
change into one another, the white into the blue, and the
blue into the white; that the white is merely the blue altered
by heat, pressure and chemical alteration and crystalliza-
tion; that the change is alwaj^s at the contact of some plu-
tonic rock, and in proportion to the quantity of the disturb.
between this quarry and the northern edge of the belt [of York county
limestone] is generally white and of a more earthy character than the aver-
age York limestone. The pebbles were of course fragments of an older
limestone than that which enclosed them." See also his report C, Chapter
XII, p. 303 ; and his analyses of six different limestones, on p. 307.
WHITE LIMESTONES AND MARBLE3 OF NO. II. 475
ing agent; and that all the steps of the change of the blue
into white are easily observable.
The distinctive features are: (1) that the White is crystal-
line and sparry, a true marble; the Blue, granular, a true
limestone; (2) that the White contains an abundance of
graphite (plumbago) crystals; the Blue, little or no graph-
ite; (3) the White has no fossils; the Blue has fossils.
But on the other hand: (1) The White is not always
highly crystalline and sparry; nor is the Blue everywhere
non-crystalline and blue. (2) The Blue sometimes carries
graphite and fossils as well. (3) The White marbles grad-
uate into a fine-grained clouded blue marble (like the door-
step marbles once so commonly used in Philadelphia) ;
while the Blue ranges from an earthy granular to a white
or cream colored graphite marble. (4) The White, slightly-
changed limestone holds flinty nodules nearly or quite
changed to crystalline quartz; but the Blue limestone also
has characteristically large flint nodules, which often, al-
though not at all changed, have scales of graphite enclosed
in them. (5) The White beds have boulder-like masses of
fine-grained, banded limestone, surrounded by coarsely
crystalline marble. (6) The Blue limestones are often
crushed into breccia, the fragments being cemented by crys-
talline limestone, and both the fragments and their cement
carry graphite. (7) The quantity of graphite in the White
marble beds, in the Blue limestone beds and in fossiliferous
sandstone beds, increases as the distance diminishes from the
face of the igneous rocks which have produced these changes.
(8) A last fact of the utmost importance; sandstone beds
of exactly the same texture and mineral composition under-
lie both the White marble and the Blue limestone, and are
changed intoquartzite beds, holding graphite, when in con-
tact with the igneous rocks. These sandstones are some-
times conglomerates, holding large, irregularly shaped,
rounded pebbles of quartz. When changed the sandstone
shows crystals of fresh looking feldspar (orthoclase ?) and
white mica scales, and is then hard to distinguish from the
neighboring igneous granite. Hematite and limonite de-
476
GEOLOGICAL SURVEY OF PENNSYLVANIA.
cunt
Thin-tedded loncitoM. ^ . White and jxle tlut man<ti*n hmetlone. \ JynclinaL
Yalley limcilene rritk vertical dip and clearage,
Comhchoct-en
Vdllny limettcne wit/tout cleavage
JoutA i,fJt f o
'fif-ZZ.Settim nort&tfCoafarifa, l^ciony northeast.
Jio:~23.36c&m tiroatft-tht "JiiU-nirA fffSfirfatajy.
WHITE LIMESTONES AND MARBLES OF NO. II. 477
posits are associated with both the sandstones and lime-
stones. *
In the Chester county valley we have the same grouping
of white marble beds, blue-banded marble beds, blue fos-
siliferous limestones, sandstones converted into quartzite,
graphite crystals and limonite deposits. We have the same
limited range, and local distribution of the white marbles.
But we have no igneous rocks except the one narrow trap
dyke which crosses the Schuylkill at Conshohocken ; for
the nearest granite is several miles away to the south. But
the trap ranges with the marble beds ; and these are wholly
confined to the vertically upturned south side of the valley.
The conversion of blue limestone beds into blue-banded
marble and into crystalline marble may have been produced
by pressure.
In fact I had pieces of white marble ground thin enough
to become transparent, and then under a microscope of
high power it was evident that the rock had been crushed
to minute fragments and recemented with a deposit of cal-
cite, which gave the white color and sparry appearance ;
and it could be seen that all the fragments had been thrust
more or less round their centers, for they were minutely
banded, or crossed by fine lines, which obeyed no common
direction across the field of vision. I consider this a phys-
ical demonstration that the white marble was originally a
common limestone, and that its formation as marble had
nothing to do with either the presence or absence of any
trap or granite or other heat agency, but was effected by a
crushing pressure which permitted the complete infiltration
of lime water, and the recementation of its fragments with
precipitated calcite.
* Report of 1890, pp. 36, 37. Prof. Dana's objections to Mr. Nason's views
may be found in a notice of the N. J. report published in the July No. of the
Amer. Jour. Sci., 1891. To these objections Mr. Nason replies in the Sep-
tember No. of the American Geologist, 1891, pages 166 to 171, by a clear and
succinct restatement of his field observations, laying special stress on the
fact that the change of blue limestone beds into white marble beds may be
seen between two points only 50' apart. " The graphite exists in every stage
from the bright crystalline stage to cloud aggregations of carbonaceous
matter which give the blue color to the blue limestone."
478 GEOLOGICAL SURVEY OF PENNSYLVANIA.
As for graphite, its occurrence is too general in different
kinds of rocks to base a very valid argument upon its pres-
ence in any one kind of rock. It is widely disseminated
in slate rocks ; and the dark grey color of the Peach
Bottom roofing slates is produced by so small a quantity as
only 0.5 per cent. The dark limestone beds of the Lehigh
valley are colored -by impalpably fine graphite. At Pugh-
town in Chester county, beds charged with graphite have
been ground to make paint. Sometimes its molecules are
aggregated to form small scattered crystals or scales ; as in
crystalline limestone on Monocacy creek 4 m. IN", of Bethle-
hem ; in the magnetic iron ore at Siessholtzville, Lehigh
county; in the limonite ore at Yellow Springs, Chester
county ; in bluish and other quartz in various parts of Ches-
ter county. Granular and foliated masses of it are embedded
in the talc and tremolite beds of Chestnut Hill, N. of Easton.
It occurs massive at Robinson's Hill, 5m. N. of Philadel-
phia ; and at Van Arsdal's quarry near Feisterville, Bucks
county. A mine of very pure plumbago was worked a cen-
tury ago near Bustleton, Bucks county.*
The disseminated microscopic graphite in slate rocks may
be ascribed to an original charge of organic matter (animal
or vegetable, or both) in the oceanic mud. The same ori-
gin may be suggested for disseminated microscopic graphite
in the limestone formations. But when it comes to ex-
plaining disseminate crystal plates of graphite in limestone
changed into marble, it would seem to be necessary not
merely to call in the aid of destructive chemistry to set free
the pure carbon from the organic hydrocarbons, by driving
off the hydrogen to other alliances, but furthermore to call
in the aid of those forces of crystallization which have
operated in and upon all the most ancient an so called
azoic formations, in fact upon all disturbed, complicated
and crushed formations, chiefly through the medium of
universally and perpetually permeating mineral waters, f
*Vanuxem's analysis gave: Carbon, 94.4; silica, 2.6; ox. iron and mang.,
1.4 ; water, 0.6 ; loss, 1.0. On the other hand, samples from S. Coventry and
from Berks county gave to Genth : Carbon, only 7.20 and 10.85. (Report B,
1875, p. 8, for all the details in the text above, and in this foot note.)
t The geological reader of these remarks may be reminded of the flakes of
WHITE MARBLE IN CENTRE CO. 479
The white magnesian limestone of New Jersey seems to
have been the only one quarried for lime burning before
1864.* One analysis gave it as much as 42.26 curb, mag-
nesia, only 1.40 alumina and oxide of iron and 2.90 of silica
and insoluble matter ; while a fossiliferous limestone had
only 1.98 carb. mag., 4.70 alum., etc., and 5.80 sil., etc.
Yet it is well known that piire limestone makes a white and
stronger lime, swells more in slacking, and is a better flux.
The white crystalline limestones in tlie gneiss of the N. J.
highlands, along their whole northwest border, are very like
the sedimentary limestones of No. II. One analysis gave
96.50: 1.13: 1.30: 0.30; another, 53.00: 42.26: 3.50: 0.50.
Consequently one was a pure marble, the other a dolomite. f
White marble in Centre Co.
It is certainly a surprising fact that white crystalline
limestone, or white marble, should have been quarried on
Jac. Bahrrer's farm near Buffalo run in Patton township,
Centre county, and the slabs sold in Hollidaysburg in Blair
county for gravestones ; the strata being at about the
middle horizon of the great formation No. 114 There seems
to be but one way to account for it, viz : by the infiltration
of limewater to such an extent as to completely charge the
rock with crystals of calcite. But such infiltration pre-
supposes a complete crushing up of the rock, as in the case
of the Chester Valley marbles, which we find in all stages
of change from pure white to blue and white ribbon marble.
But the Chester Valley marble strata have been pressed
into a perfectly vertical attitude between a vertical slate
formation 1000 feet thick, backed by gneiss and granite on
asphalt, or anthracite, in the quartz crystals of the Mohawk valley, and
other places. They seem to have been deposited in internal rifts in the
crystal ; but they are completely enclosed in the body of the silica, and per-
haps floated in it when it was in its gelatinous condition, the crystallization
going on around them.
* Cook, An. Rt. 1864, p. 8.
t Cook, An. Rt. 1864, p. 15.
t Prof. Ewing's special report in Report T4, page 417.
The dark blue Trenton limestone beds are in many places full of cracks
filled with a cement of white calcite ; and scattered crystals of pure or nearly
pure calcite are quite common all along the outcrops. (T4, 417.)
480 GEOLOGICAL SURVEY OF PENNSYLVANIA.
M.l I &?nadone in, <M/rnfy(miery and (Sfwfor Gat.
.Gh,. XXXIX.
fy.19.
Sen/an Km HillarCrat toJha&Srmk .VorrtondiAkinylan TotmiAipt.
Ky.20.
the tost end of the tinimtonf raller . Ak union Toimtfup.
Tly.ll.
Kff.M.
Ill
Hg.
n-n I
ihnugk anthoHorln-n ISpriiy Mill atony , Irh&kll Krrr,
Srtion akny the SduylMI IB- itwyh If. CW/oWAv, . I'rprr
WHITE MARBLE IN CENTRE CO. 481
one side and a badly crumpled limestone formation perhaps
3000 feet thick, on the other ; with every kind of evidence
of oblique strains just suited to the disintegration of the
mass, exposing it to easy and continuous infiltration.
In the Nittany valley the great anticlinal is indeed in
places overthrown, and therefore the slip and slide move-
ment must have been great ; but the wave form is normally
regular, and oblique crushing not a necessary consequence.
Yet it may have occurred at particular points, perhaps
many such ; and must have occurred at Bahrrer's quarry.
It is, however, astonishing that the infinitely varied and
minute complication, distortion and warping of the lime-
stone strata of the Great Valley should not have produced
the same effect upon them as in the Chester Valley ; should
not have created white marble quarry-ground at least equal
to that of New Jersey or Vermont.
Near Ephrata, in northern Lancaster county, a quarry
was opened many years ago from which were obtained some
good pieces of marble of a very light blue tint and some of
it decidedly shaded. Gteol. Pa. 1858, Vol. 1, p. 222.
81
482 GEOLOGICAL SURVEY OF PENNSYLVANIA.
CHAPTER XL.
Black marble in No. lie.
The "black marble" of the Musquito or Oval valley in
Lycoming county, Armstrong township,* is a unique rock
in Pennsylvania, and very interesting because (1) it exactly
resembles a Belgian black marble (with a brownish reflex-
ion) used for the body of French mantel clock cases, f (2)
it marks the depth to which this oval hole in the Bald Eagle
mountain has been excavated; for the black beds are un-
doubtedly high in the Trenton limestone, the upper division
of formation 114
These beds are crowded with brachiopod shells, and con-
tain many specimens of Calymene senaria, Conrad, one of
the most characteristic and widely distributed trilobites of
of Trenton age.
A similar black marble is quarried at Glen's Falls in
* Four miles southwest of Williamsport. The quarry is owned by the
Penna. Marble Co. (Col. Potts and Mr. A. D. Hepburn). The valley is 5
miles long, and its floor about 500' above the river at Williamsport (or, about
1000' A. T.). Quarry abandoned about 1875, because no blocks thicker than
10" or 12" could be got out from the 36' of face exposed. Layers dipping
only 4 N. E. representing a fall of the crest of the anticlinal arch in that
direction (See Report G2, 76, 78). Curiously enough the rock has not been
found in Nippenose valley.
f Much of the rock is splintery. Soft rotten layers separate hard firm
layers. It burns to a fine white lime. It will not polish well by ordinary
processes, but can be polished highly by extra care. It breaks up when ex-
posed to the weather, but is useful for indoor furniture (Letter of J. G.
Hammer, March, 1886).
JSee however the so called black marble of Hitner's quarry in Mont-
gomery county mentioned in foot note to p. 471 above, last paragraph.
Vanuxem's Senior calymene (N. Y. Rt. 1842, p. 56), a name which has
no reference to the 6 tubercles on the buckler (Miller's Am. Pal. Foss., p.
213). Conrad named it in 1841. Green in 1832 gave figures of three casts
which he called C. blumenbachii, C. callicephala, C. selenecephala, which
J. Hall considered synonyms of C. senaria (Pal. N. Y., Vol. I, p. 238, Plate
64, fig. 3a-n).
BLACK MARBLE IN NO. He. 483
northern New York.* Dr. Emmons describes it as there
exposed in a river cliff 65' high, the upper rocks being
Trenton limestone, the lower calciferous (Chazy) limestone.
Between them lies the black marble formation 10' thick, f
So, at Isle La Motte the black marble (solid 12' thick) lies
under Trenton limestone. Where it occurs at Watertown
on the Black river in Jefferson county it is lumpy, and lies
between the Trenton and Birdseye. It is nowhere seen in
the Mohawk valley, where the Trenton reposes directly on
the Birdseye limestone ; and this makes the fact of its ap-
pearance in the Oval valley in Pennsylvania, and nowhere
else in the state, as yet noticed, so remarkable and interest-
ing. It makes it doubtful also whether our black marble
is really the same deposit under the Trenton, instead of
being over it. In fact it seems almost impossible to believe
it the same : for the Trenton is nearly 1000' thick on the
Bald Eagle anticlinal ; and the Oval valley should be much
larger if eroded to the bottom of the Trenton.:}:
* The black marble at Glen's Falls is so checked, cracked and seamed
with flints and calc spar fossils, that very few beds can be worked with
profit. Its color is jet black, its grain close and fine and slightly crystalline.
Being rather brittle in one direction it requires careful handling for thin
tables. The natural division planes between two beds often are studded
with projections like those of fibrous sulphate of strontian, fitting into each
other, and sometimes kept apart by a thin film of slate, showing minute fu-
coidal markings, and now and then a small encrinite.
fNat Hist. N. Y. 1842, pp. 110 and 180. He says that the Trenton beds
here are 60 or 70 in number varying in thickness from an inch to several
feet, full of Trenton fossils. The bottom layers are gray and lying on the
black marble are quarried with it.
i Emmons says that the black marble fossils are not exactly those of the
Trenton. They are not very numerous in the New York quarry rock.
Columnia sulcata is quite abundant, sometimes in masses of half a bushel.
Large Orthocerata are common, some of them ten feet long and a foot in
diameter (as in Birdseye). He describes cone-in-cone as a fossil (p. 111).
The strontian-like crystals are half to one inch long. In the later Niagara
limestone the mineral itself has been preserved ; in this black marble only
its form (p. 111). Both these projections and the cone-in-cone show that
the black mud remained homogeneous and quiet for a long time ; no doubt
as alocal marsh, but either subsequently covered with deep water ; or along
an extensive shore to which storms might drive the gigantic cephalopod
shells and masses of coral to be embedded in the black mud when dead,
although they could not have existed even in its vicinity while alive.
Vanuxemin his Report (N. H. N. Y. Third Dist. 1842, p. 43-45) described
some light grey or dark grey limestone beds, on the Birdseye and under the
484 GEOLOGICAL SURVEY OF PENNSYLVANIA.
Black marble in No. VI.
There is a so-called black marble in New York in Forma-
tion No. VI. It is the lowest, or Tentaculite limestone sub-
division of the Lower Helderberg group, the layers of which
are massive and dark colored.*
Trenton, at the Mohawk valley quarries (in three layers 2', 4' and 7' thick,
at Stanton's quarry), holding accretions, or knobs, and (at Putnam's
quarry), the lower layer what seem to be 4' pebbles of yellowish calciferous
sandrock. The beds are as good limestone as the Birdseye beds under them
but otherwise resemble the Trenton beds over them. They hold a shell
(Strophomena), a polyp, a coral (Cyathophyllum}, etc. Vanuxem adds,
that these bottom beds of the Trenton form the surface of Nippenose (Mus-
quito) valley in Penna.; the 30' "marble" cliff at Frankford, Ky. (with F.
demissus specks); and the Nashville bluff in Tennessee, where the layers are
brown and thin.
Mather in his report of the First Geological district of N. Y. (1843, pp. 399
and plate 24) describes the black marble of Glen's Falls near Saratoga more
in detail. The Hudson cuts through 70' of beds : Utica black slate at the
top, on Trenton limestone, sawed for fire places ; fifty layers ol very fossil-
iferous limestone ; 2|' grey limestone taking a fine polish ; 6" darker lime-
stone used for door steps ; 10^' black marble polishing brilliantly, with lay-
ers of fossils at irregular intervals, 2" or 3" thick, and extending 10' or %0'
and abruptly stopping (i. e. shell banks). Mather (p. 403) places the Isle
la Motte black marble of Emmons in the Slack River Limestone group,
with the Birdseye and Chazy.
* Mather alludes to it in his Report of 1843, p. 327, where he says that most
of the Helderberg rocks south of the Catskill mountain are black, dark grey,
and veined with white, but massive, and susceptible of a polish. Vanuxem
in his Report of 1842, p. 118, calls the Pentamerus beds mottled brown and
blackish limestone full of columnarice.
THICKNESS OF NO. II. 485
CHAPTER XLI.
Thickness of No. II in Lancaster county and elsewhere.
The city of Lancaster is built over the center of a great
limestone plain of inexhaustible fertility, the garden of the
State. It reminds the traveler of Paris seated in the
center of the fertile and populous plain of Northern France,
through which meanders the river Seine, as the Conestoga
meanders through Lancaster county from northeast to south-
west to join the Susquehanna at Safe Harbor. But here
the likeness ends ; for the Cretaceous strata of the Paris
basin lie almost perfectly horizontal and are charged with
the rainfall which has collected in them from a circle of
many leagues, and which is easily brought to the surface
by artesian wells.
The Lower Silurian limestone strata of Lancaster county,
on the contrary, descend steeply to the bottom of a syn-
clinal trough at least a half mile beneath the present sur-
face, the center line of which runs east and west, crossing
the Conestoga about a mile below the city's southern limit;
almost all the observed dips at the surface south of this line
being N. dips ; and almost all of those north of the line be-
ing S. dips; the exceptions in both cases must be ascribed
to local crumpling.*
* Frazer's Report 03, 1880, page 58, 59. This description in the text does
not exactly consist with the hypothetical curves of the N. and 8. long sec-
tion from Neffsville through Lancaster to Martin ville published in Atlas to
C3. The section was drawn subsequently after a careful discussion of the
surface dips, and shows two deep basins, instead of one; the northern basin
being under the city and of great depth ; the southern basin being south of
the city, not so deep, and with a broad rolling bed line. But geologists who
had dealt much with a folded country will appreciate the difficulties in the
way of an even approximately correct underground construction of curves
based on surface dips most of which have angles between 60 and 90 and
many of them probably overturned. The section has the merit of corres-
ponding to the two synclinal limestone belts which cross the Susquehanna,
one at Columbia, the other some miles lower down. See the colored geolog-
cal map of Lancaster county in Atlas to C3.
486 GEOLOGICAL SURVEY OF PENNSYLVANIA.
The Lancaster section is described by Dr. Frazer in a
most interesting manner in detail on pp. 145 to 158 of Re-
port C3. The object of the section was to obtain the thick-
ness of the formation and its depth beneath the city of
Lancaster.*
Dr. Frazer remarks that the dips seem to require one
complete synclinal and one and a half anticlinals, between
the northern Lancaster township line and the Conestoga
where the section line crosses it. Two points in the city
are indicated where the limestone bottom is nearest the
present surface, one just south of the north city line, the
other between Conestoga and Hazel streets ; but the depth
cannot be measured on account of the high loops which the
strata make, and the slip of bed on bed. He then uses an
ingenious mathematical (geometrical) rule discussion (p. 150)
and concludes that it is only safe to say that the total
thickness of the limestone measures before erosion in the
vicinity of the P. RR. station was not less than 2700 feet. f
* The section was started as far north as Neffsville because the lowe
slates there come to the surface (with fragments of Chikis quartzite) and
continue at the surface for 1000'. A limestone quarry is crossed 250' further
south. At 1600' a L. crop dips about E. showing how crumpled the country
must be. At 1| m. pale limestone dips only 6, S. 20 E. Close by, a quarry
reads 20 S. Then one reads 20 N. Then 500' further 60 N. W. Another
24, N. 20 W. At Myers' quarry a quartz seam 18 N. ' All this indicating
the N. side of a gently sloping anticlinal ; the same is indicated for 3500
further. At Dillersville a RR. dip reads 38, S. 15 E. which seems to
begin the descent of the beds on the S. slope of the anticlinal ; soon, 50.;
35, S. 25 E. Then a synclinal; for, at the divergence of the P. RB. and
R. RR. is seen an (overturned) dip of 80, S. 15 E. (Another before cross-
ing the township line, 75, S. 15 E.) Then in Lancaster township 80, S.
150 E. Then the south side of the anticlinal, 500' from last, 30 S. Where
the two RRs. cross, 70, S. 15 E. In the cut just E. of Lancaster station,
67, S. 15 E. No exposures for 500'. Where Vine street crosses the Quar-
ryville RR., 70, S. 5 W., continued for 165' to the Soap Factory; the
rocks turning gradually into a curly hydromica schist, showing that the
bottom beds of the formation here rise again to the surface. And so the
record of the section runs on southward.
f From the Conestoga south to Mill creek the details of the section are
narrated and the conclusion reached that the whole series of minor anti-
clinal and synclinal rolls are crossed. Between Mill creek and D. Harnish's
house, 5 minor anticlinals, the whole body of measures rising southward.
Then a gap in the record of 4400' near the middle of Pequea township. The
southern portion of the section is extraordinarily difficult of construction,
as both mica slate and gneiss exposures occur in it. See C3, pp. 156 et seq.
THICKNESS OF NO. II. 487
This deep basin extends from the Salisbury cove in the
mountain land of Chester county westward across Lancaster
county ; and beyond the river is continued as the York
county limestone valley to Adams county.
Another equally deep basin runs the Conestoga valley
north of it, parallel with it, from the Berks county corner,
westward, to the Susquehanna above Marietta, and so into
York county.
Many other smaller basins cross Lancaster 'county, ob-
scurely, in a parallel series, the exact shapes of which can-
not possibly be made out from surface dips, because there are
no well denned characteristic marks to distinguish the lime-
stone beds from one another; and all the basins are so con-
nected sideways with each other that the strata pass over
the upfolds from one basin to the next ; the whole being
eroded to a general plane surface.*
The most southern basin which has preserved its lime-
stone rocks is that of the Chester county valley; and this
deepens eastward, and then shallows to its end in Mont-
gomery county. The widest and probably, therefore,
deepest part of this Chester county valley is between Down-
ingtown and the Schuylkill; but the beds are so complicated
by longitudinal anticlinal and synclinal waves, as shown
in the sections on plates 45, 46, 47, that it is impossible to
calculate with any approach to accuracy the thickness of
the formation which remains at the present day, to say
nothing of its original thickness before the erosion of the
contents began to remove from over it the slate formation
of No. III. At least 2000' and perhaps 3000' of it still re-
main. It may have been as thick as it is in Centre county;
* There can be no reasonable doubt that the Azoic country of southern
Lancaster, southern Chester and Delaware, on the one hand, and southern
York and eastern Maryland on the other hand, were each and all once cov-
ered with the Lancaster limestone formation II. Nor can any reason be as-
signed why the formation as a whole should not have been formerly as
many thousand feet thick in its extension to the Atlantic, as it is now seen
to be at Lancaster and Harrisburg. Its great thickness at York, at Lan-
caster and at Downingtown is an absolutely satisfactory guarantee of its
ancient unbroken extension southeastward over the present Atlantic coast
region.
488 GEOLOGICAL SURVEY OF PENNSYLVANIA.
but that is not probable; for there is no part of the Great
Valley in which such a thickness can be proven.
In the Great Valley we have also everywhere an exces-
sive complication of the limestone strata of No. II. There is
no section from the Delaware at Easton to the Potomac in
Maryland where a fair and unimpeachable measurement
of the formation can be made; and the faulting along the
southern edge of the Great Valley prevents us from even
estimating the amount which has been removed by erosion.
Two or three thousand feet of limestone strata are evidently
present at the surface; how much more we cannot tell.
In the coves and valleys of middle Pennsylvania most of
the formation is concealed underground. In Nittany valley
alone, along the Little Juniata river has a good opportunity
been granted to measure the formation, and even here not
quite to its base at Birmingham. But the locality is most
favorable to the inquiry. From the Canoe mountain syn-
clinal to the Nittany anticlinal the dips 'are all one way and
the sequence apparently unbroken. This noble section has
been repeatedly criticized and measured with the greatest
care; first by Mr. Rogers in the First Survey, and lastly by
Mr. Platt and Mr. Sanders in the topographical survey of
the Blair county region, published (text and sheet map) in
Report T, and Atlas. On the basis of this survey, which
took account of all the dips of all the exposed rocks along
the river on both sides of the Canoe mountain synclinal,
there were counted up 6600'; subdivided thus : Upper lime-
stone series, 5400'; Middle white sandstone beds, 40'; Lower
limestone series, including some sandy or sandstone layers
at bottom which may belong to the Chiques (Cambrian)
quartzite system, 1160' =6600' .*
*T, p. 52. Mr. Sanders has measured 3000' of consecutive layers at Har-
risburg. Mr. Prime measured only 2000' at Allentown. In Report O, Vol.
I, of the catalogue of the Geol. Museum, 1878, p. 1J3, is given a list of 240
specimens collected from the outcrops of II along the Little Juniata from
Tyrone Gap down to Spruce Creek. These are summarized in T, page 58.
These collections by Mr. C. E. Hall show an extraordinary dearth of fossils
in the formation; but Trenton and Calciferous New York forms were cer-
tainly identified. Mr. Hall remarks on the special steepness of the dips, and
on the fact that the dips do not correspond well on the two sides of the river
(T, p. 59).
THICKNESS OF NO. II. 489
When the limestone formation No. II sinks at the foot of
Bald Eagle mountain it does not rise again to the surface
for 100 miles, to the Mohawk valley, in New York. The
depth to which its uppermost division, the Trenton, He,
sinks beneath the highlands of Lycoming county is 15,000
feet.*
After the developments of gas and oil in the Trenton
limestone in western Ohio and in Indiana a large number of
wells were bored in northern Ohio, in Upper Canada and
in western, middle and eastern New York to test the oil and
gas value of the formation along the belt of country where
it was known to lie undisturbed and not too deeply cov-
ered to be reached at reasonable rates of expense, say 3000'
or 4000' feet beneath the surface. f
At Ithaca, N. Y., a test well (in the valley) said to be
3185' deep, stopped in the middle of formation No. V, and
should have gone down to 4755' to reach the top of the
Trenton.:}:
From Ithaca northward the rise is very gradual to the
outcrop of the top of the formation at Trenton Falls where
the upper division of No. II got the name in 1835 which it
has retained to the present day. It is quarried along the
banks of the Mohawk, south of which it is covered by the
* As measured by Dr. Chance, in Clinton county, Lock Haven long sec-
tion, Report G4, p. 124. Its depth beneath Cresson, or Ebensburg, in Cam-
bria county, according to the section by Platt and Sanders (Appendix A to
Report F, p. 262) is about 17,000'. Its depth beneath the Mountain House on
Broad Top in Huntingdon county is nearly 18,000' (see F, p. 184). Between
the tost two mentioned depths it rose into the air over Birmingham 6000'.
The Nittany valley anticlinal was, therefore, a rock wave 25,000' or 26,000',
i. e, 5 miles, high.
t These borings have greatly enlarged and improved our knowledge of the
Palaeozoic formations, especially as to their varying thicknesses, and as to their
condition and quality beneath different sections of country. The bore-hole
records have been discussed very skilfully by the late C. A. Ashburner, and
by Prof. Prosser, of Ithaca, N. Y., now of the U. S. Geol. Survey at Wash-
ington.- The facts thus obtained will be frequently used in subsequent
chapters of this report.
J C. S. Prosser, " The thickness of the Devonian and Silurian rock of west-
ern central New York," in the Amer. Geologist, Oct, 1890, p. 202, 211. The
estimates from data furnished by the Syracuse well would make the depth
5172'; the estimate from maximum thicknesses in general section would
make it 5708'.
490 GEOLOGICAL SURVEY OF PENNSYLVANIA.
Hudson river and Utica slates of III, 3500' thick, through
part of which the Knowersville gas test well, 3000' deep,
went down and penetrated the upper 120' of the Trenton,
to which Ashburner's Catskill section assigns a total of
500.'*
The Wolcott well, in Wayne county, N. Y., on the south
border of Lake Ontario struck the top of the Trenton at a
depth of 1950', and stopped, still in Trenton limestone, at
2700'. When it is remembered that the greatest depth of
the lake near its southern shore is about 700', we can under-
stand the true formation of the great valley of erosion in
which its waters are held a valley excavated in very an-
cient times by the chemical solution of the great limestone
formation No. II, and the mechanical removal of the over-
lying slates of III and sandstone of IV (Oneida and Medina)
the outcrop of which makes its steep, half submerged south-
ern shore, f
Onr better knowledge of a greater thickness of II and
III in the Mohawk country than has hitherto been allowed
them is very satisfactory on the score of bringing their
distinct areas into closer harmony with their great exhibi-
* Petroleum and Natural Gas in New York state. C. A. Ashburner, Trans.
Amer. Int. Min. Eng. Duluth meeting, July, 1887, foot-note to page 49 of
paper. For geologists the record of this well is uncommonly valuable,
greatly increasing the traditional thickness of III. to which in W. New
York only 800' to 1000', and on Georgian bay in Canada only 770', was as-
signed. The Utica in Montgomery county, N. Y. west of Albany, has been
called 250'; but the Campbell well west of Utica went through 710' of it,
Walcott calls its outcrops on the Mohawk 600'. As to the Trenton, Vanuxem
only gave it 300' in Lewis county. Emmons made it 400'. In Canada
Logan measured 679' and 750'. Walcott makes it in the Campbell well near
Utica 430' and the surface outcrops 290' (Proc. A. A. A. S. Vol. 36, p. 212).
Prosser gives a general thickness of 820' to III, and 992' to II (Trenton 842'-
Calc., 150').
t Lake Ontario, if drained of its water, would be a repetition of our Great
Valley, with the difference that the two formations II and III lie almost flat
and undisturbed instead of being crumpled and crushed ; the limestone
(II) rising northward out of the water, and constituting the great plain of
the St. Lawrence. It must be understood that Ontario has been considera-
bly refilled by glacial deposits, etc., since its submergence. Its old bed is
far deeper than its present bed, probably 2000', and was originally deeper
towards the northern shore than towards the southern. This also irrespec-
tive of the tilt which it has suffered in recent times.
THICKNESS OF NO. II. 491
tions in Middle Pennsylvania ; and also in another respect,
namely, by adding one more line of evidence for their
identity with the so-called Taconic limestones and slates of
the western border land of New England. For it is incred-
ible that 4500' of II and III should exist 15 miles west of
Albany, and not be well represented in the Taconic region
east of Albanv.
492 GEOLOGICAL SURVEY OF PENNSYLVANIA.
CHAPTER XLII.
Oil and Gas in No. II.
Dr. Orton says that the Trenton limestone when followed
northward both in Ohio and Indiana suffers a transforma-
tion through a small thickness of its upper beds, by these
upper beds losing their pure limestone character and be-
coming dolomitic or magnesian ; and that this change
affects frorn 10' to 50' of strata at the top of the formation ;
perhaps in rare instances 100 feet. Generally the wells
passed through magnesian limestone from the very top of
the formation downward ; but in some cases pure limestone
is found at the top of the formation over the magnesian
strata ; and in every such instance the magnesian lying
directly upon the pure limestone.*
The line along which the change from limestone to dolo-
mite occurs, passes through Hancock, Allen and Mercer
counties southwesterly into Indiana, and so onward through
Jay, Randolph and Henry into Indiana ; and this is the
* Dr. Orton's language implies a theory that the formation was originally
pure limestone, and has been partially changed to dolomitic limestone by
the introduction of magnesia; for he adds, "In other words the change is
comparatively superficial," and he speaks of "normal or unaltered lime-
stone." This theory is much in vogue among European geologists, although
it is also strongly opposed. In Pennsylvania the theory has been com-
pletely broken down by the statement of facts narrated in Chapter XXVIII,
p. 327 above.
In Pennsylvania the Trenton limestone as a formation and judging from
a very insufficient series of analyses of specimens collected at hazard in
different parts of the State, has been called a pure or non-magnesian lime-
stone ; but our knowledge of its chemical composition is still extremely
limited, and the only safe assertion which can be made respecting it is, that
as a formation hundreds of feet thick it contrasts in a general way with the
great limestone formations under it (Calciferous) in being less magnesian.
I have no doubt, however, that if many thousands of analyses of Trenton
specimens from the extensive outcrops in Pennsylvania were made and
compared it would be discovered that the formation contained locally
magnesian beds, in other words, that the same phenomenon described by
Dr. Orton in the gas fields of Ohio and Indiana would recur in various
places in Pennsylvania.
OIL AND GAS IN NO. II. 493
boundary of the new gas and oil fields. Bur in Ohio it/ex-
tends from the present gas and oil fields northward and
westward ; and patches are sometimes found to the north-
eastward. In Indiana it appears to extend to the northern
and northwestern boundaries of the State ; and is presumed
to underlie the entire peninsula of Michigan, on the strength
of a few analyses from borings in that State.
The porosity of the rock is supposed to be connected in
some way with its charge of magnesia.*
*Dr. Orton says, "To be a reservoir of oil or gas the upper surface of the
Trenton limestone must have suffered the dolomite replacement, whereby
due porosity has been conferred upon it, and it must also have received in
the accidents of its history the due relief by which its varied contents have
been separated and accumulated," but if the magnesian limestone was not
introduced afterwards but was a part of the original deposit, the porosity of
the rock must be explained by the superior solubility of the magnesian car-
bonate above the lime carbonate. It is strange that in the abundant litera-
ture on this subject so little notice is taken of the presence of salt water in
the porous rock at the lower limit of the oil and gas belt ; at what is called
the dead-line in the Findley field. This dead-line in the Findley field
follows the hypsometric line of 500' below sea level ; every well which
strikes the Trenton limestone at this level or at lower levels has found the
rock charged mainly with salt water. In the Lima field a similar dead-line
400' or more below sea level has salt water on the southwest of it, and oil
and gas on the northeast of it ; the productive wells striking the limestone
at from 390' to 350' below sea level. In Indiana the dead or salt water line
surrounds the productive territory on the north and west at only 100' below
sea level. The limestone gradually rising southward without any anticli-
nal or terrace structure, the gas production ceases abruptly and without
any apparent reason. Dr. Orton proposes as a probable explanation for this
fact the change of the formation from dolomitic porous limestone to pure
tight limestone ; but in doing this he virtually discards the reason given
for the upper limit of gas production in the Findlay and Lima regions,
namely, an anticlinal or rather a terrace structure.
I have just said that it is strange to notice in the literature of the subject
a prevailing indifference to the value of the fact of the universal presence of
salt water below the dead line. Surely some explanation of the existence
of that salt water must be taken into the theory. First, a question arises re-
specting the age of that saltwater. Is it the original sea water in which the
Trenton limestone was deposited ? if not, is it salt water which has pene-
trated from any ocean past or present? if not, is it analogous to the salt
water of closed basins, seas or lakes which have no outlet? in other \\ords,
has the rain water obtained salt from salt-bearing formations and collected
as salt water in this Trenton reservoir? if not, does the saltin this saltwater
represent an original element of the formation itself, namely, a certain
charge of chloride of sodium deposited originally with the carbonate of lime
and carbonate of magnesia ; and subsequently through the ages dissolved
out by the percolating rain water, which has ever since held it in solution ?
494 GEOLOGICAL SURVEY OF PENNSYLVANIA.
Why no Trenton oil or gas in Pennsylvania.
To the people of Pennsylvania the practical question is
simply this : Does the Trenton limestone formation in Penn-
sylvania hold, and will it, if bored down to, furnish a future
supply of oil or gas, or both, to supplement the rapidly ex-
hausting oil and gas pools in the Devonian oil sands of the
western counties ? The answer is :
Certainly not in southeastern Pennsylvania.
Certainly not in middle Pennsylvania.
Probably not in the rest of the State.
if so, such dissolvine out of original crystals of salt has of itself played a
certain part in the production of the porosity of the rock. The above are
important questions which, so far as I know, have never been properly
presented, much less answered. And their range of application in geology
far exceeds the limits of oil and gas regions ; in fact, take in all brine regions.
We know little enough of the methods of nature in past time as to the de-
posit of sandstone strata ; but we know far less respecting the mode of an-
cient limestone deposits, under conditions of topography and climate so
different from anything we now see that arguing from the present to the
past is almost impossible. The present river drainage of the world carries
chiefly clastic detritus : that is, most of the land being destroyed by rain-
water and transferred to sea bottom has already undergone that process
once or many times. But in the Lower Silurian Age it is reasonable to be-
lieve that the larger part of the land consisted of crystalline rock and fur-
nished by its own river drainage a very different kind of material to a sea
much warmer, perhaps hot, in which chemical re-actions took place on the
grandest scale. Dr. T. S. Hunt has endeavored, and with much success, in
suggesting a picture of the operations of that ancient time ; or rather of a
time far more ancient when chemical precipitation was probably almost the
only form of ocean deposit. The Lower Silurian Age indeed stands midway
between the first age of nearly pure chemical precipitation and a percentage
of almost pure mechanical deposit ; and it therefore ought to represent by
the nature of its rocks both kinds of operation, intermingled indeed in a
manner to confuse very completely geological judgment.
Dr. Hunt's crenitic hypothesis (cr6n6, a fountain) is an admirable attempt
to solve the first great difficulty in geology, namely, the source of those ele-
ments, alumina, lime, magnesia, soda, potassa and iron, which make up al-
most the whole crust of the earth. Oxygen and chlorine holding these ele-
ments in solution were of course in ancient times part of the earth's atmos-
phere. The basis must have resided in the globe either pure or alloyed in
mutual combination, but certainly not except under the condition of very
high heat. The union of the gases with them must have marked the grad-
ual cooling of the globe. But the first rivers must have been not only hot
water, but mineral water ; and the first deposits must have been chemical
precipitates. To state the case transcendentally, we may imagine (what of
course never happened in exactly that way) three rivers pouring three kinds
of mineral water into a closed basin resulting in a sea ; one discharging a
solution of lime chloride ; a second, a solution of soda carbonate ; the third,
a solution of magnesia sulphate. The common tank would become filled
OIL AND GAS IN NO. II. 495
And for the following reasons: (1) An oil rock must be
porous, but not broken up; (2) it must lie Hat, and have a
good covering; (3) it must not be too deep beneath the sur-
with these three solutions interfused; not homogeneously throughout -the
tank, but with every variety of interfusion in different parts of it according
to the respective sizes of the rivers and the sea currents which brought their
infusions together ; so that an infinite variability of chemical precipitation
would result in all parts of the sea bottom. Laboratory experiments will
certainly not teach the whole story, but will indicate certain main facts, the
first one being that a reaction would take place betweeen the river of lime
chloride and the river of soda carbonate ; the chloride leaving the lime and
uniting with the soda to make salt ; the carbonate leaving the soda to unite
with the lime, making limestone; and the magnesia also becoming a car-
bonate with different solubility, but precipitated in like manner.
Of course such a case as this is purely hypothetical and certainly could not
have occurred in Lower Silurian times, because life had already long ex-
isted ; vast amounts of carbonic acid and oxygen had already been ab-
stracted trom the atmosphere ; the waters were cool enough to permit mollus-
can and articulate life, as well as vegetation ; and the rivers had long been
pouring clastic material, gravel sand and mud into the sea. Nevertheless,
even at that late day, compared with the still more ancient times, the rivers
must have been to a considerable extent of the nature of mineral water ; and
therefore necessarily the sea was continuing, although in a very moderate
degree, its chemical precipitations ; the lime and magnesia carbonates play-
ing the chief role ; but evaporation being still probably intense, the chemi-
cal precipitation of sea salt must have played a part in the drama of depo-
sition, and has, in fact, continued to do so through all ages from that to the
present time. Hence all geological strata contain an amount of salt ; and all
atmospheric drainage through geological strata find, dissolve and bring to
the surface amounts of this salt. But I have in another place drawn atten-
tion to the remarkable fact that soda is almost absent from our limestone
strata ; a fact which makes it almost necessary to find the region of the salt
water in the Trenton formation outside of it, that is, in some of the more
decided salt-bearing sandstones.
The facts are thus stated by Dr. T. S. Hunt in his standard work, Mineral
Physiology, 1886, page 168. " The recent precipitate produced by a solution
of carbonate of soda in chloride of calcium is readily soluble in an excess of
the latter salt, or in a solution of sulphate of magnesia. The transparent,
almost gelatinous magma which results when solutions of carbonate of soda
and chloride of calcium are first mingled, is immediately dissolved by a
solution of sulphate of magnesia ; and by operating with solutions of known
strength (titrated solutions) it is easy to obtain transparent liquids holding
in a litre, besides three or four hundredths of hydrated sulphate of mag-
nesia, 0.80 gramme, and even 1.20 grammes of carbonate of lime, together
with 1.00 gramme of carbonate of magnesia; the only other substance pres-
ent in the water being the chloride of sodium equivalent to these carbonates.
A solution of chloride of magnesium, holding some chloride of sodium and
sulphate of magnesia in like manner dissolved 1.00 gramme of carbonate of
lime to the litre. Such solutions have an alkaline reaction." [Quoted
from Hunt's Chem. and Geol. Essays, page 223.]
496 GEOLOGICAL, SURVEY OF PENNSYLVANIA.
face of the earth; (4) it must either be itself very fossilifer-
ous, or be enclosed between other strata which are so.
All of these conditions are realized in the great Trenton
limestone oil and gas districts of Ohio, Indiana and Ken-
tucky; but not in Pennsylvania.
For (1) in the southeast region of our State the Trenton
has been broken and crushed arid recemented, so as to be
nowhere porous enough to hold oil or gas; (2) in the middle
region all the formations are upturned and solidified by pres-
sure; (3) in the western and northern regions, the Trenton
lies buried 10,000 to 20, 000 feet beneath the present surface,
and at temperatures between 200 and 400 Fahrenheit ; and
(4) where it shows itself at the surface in the middle, south-
ern and eastern counties it is remarkably poor in animal
and vegetable remains.
Consequently, all attempts to obtain oil or gas from the
Pennsylvania Trenton and such attempts have been made
Chester, in Montgomery, in Berks, in Danphin, in Hunt-
ingdon, in Pike, in Susquehannaandin Erie conn ties have
failed.
In the deep Erie well the Trenton was reached. In the
Canada well on the south shore of Lake Ontario near the
Welland canal, the Trenton was pierced. Several wells in
New York State penetrated it. In no case has there been
a profitable return of either oil or gas. And if this hap-
pened under the exceptionally good conditions in central
and western New York, where the formation is very fossil -
iferous, lies nearly flat, and can be easily reached, what
chance is there of success for those who bore in the uptilted
and dislocated and poorly fossiliferous strata of Pennsyl-
vania ? Where the Trenton is brought to the surface it
shows plainly that whatever petroleum or rock gas was once
distilled from its fossil corals and shells has ages ago escaped
from it; as, and for the same reasom that, the gas of the
once bituminous coal beds of Schuylkill county has escaped
from them, leaving them in the condition of anthracite.
On the other hand, who can hope for a time when oil and
gas wells can be sunk to a depth of ten or twenty thousand
feet, where the Trenton may possibly retain what oil and
gas it has at the boiling point of water or even at 400 F.
MECHANICAL DEPOSITS OF NO. II. 497
CHAPTER XLIII.
Mechanical deposits of No. II.
Ripple marks " on a superb scale " were seen on the sur-
faces of the limestone beds at the quarry close to Uhlers-
ville, on the Delaware river, in Northampton county, by
Prof. Rogers.* If there was no mistake in interpreting the
undulations as ripple marks, if they were not the effects
of subsequent pressure, and if ripple marks are to be taken
as a sure indication of wave-action in shallow water, then
the deep sea chemical theory of the formation of the great
limestone must be abandoned. And this particular case is
all the more important, as the rocks exposed at Uhlersville
do not belong to the top (Trenton) but to the bottom (Cal-
ciferous) division of No. II, overlying the Cinques quartz-
ite so full of worm burrows (Scolithus linearis) which of
course imply a shallow sandy shore. In Vermont, Brain-
ard and Seely report the whole Calciferous formation full
of Scolithus, especially some of the fine-grained sandstone
layers of the middle division (C) which are "pin-holed with
small worm burrows" (Scolithus minutus}. This division
(350' thick) is made up of alternations of sandstone beds
and magnesian limestone beds.f
All this runs in favor of the mechanical as opposed to the
chemical deposit of the limestone beds of II, as argued in
Chapter 28, p. 334 above, on the Magnesian limestone
alternations in the quarries opposite Harrisburg.
A peculiar sandstone.
The peculiarly sandy nature of the lower part of the great
limestone formation has already been mentioned. Cases
*Geol. of Pa., 1858, p. 242.
f Bulletin Geol. Soc. Amer., vol. 1, 1890, page 504; quoted in Report P4,
Diet. Foss., Pa., Vol. 3, 1890, p. 945. See also the large worm burrow Mono-
crater ion lesleyi, described from Lehigh county by Prof. Prime in Report
D2, 1878, p. 79, with figures.
32
498 GEOLOGICAL SURVEY OF PENNSYLVANIA.
of isolated layers of sandstone are given in preceding chap-
ters. The Barrens of Centre county have been described.
In Sinking Valley, near Birmingham on the Little
Juniata, a peculiar ferruginous sandstone containing also
traces of manganese and cobalt occurs in great abundance
on the farm of Mr. Galbraith. The rock is a com pact, brittle,
and exceedingly fine-grained mass, streaked with different
shades of light-red and pink and purple, which variations
it derives from the different minerals it contains. In almost
every hand specimen are numerous larger and smaller cavi-
ties, the sides of which are lined with minute quartz crys-
tals. Some portions of the mass are not unlike calamine ;
but Mr. McCreath's analysis of a specimen of it shows that
there is not even a trace of zinc in its composition. Silica,
94.9 ; ox. iron and alumina, 3.3 ; ox. mang., a trace ; ox.
cobalt, 0.17; lime, 0.06; magnesia, 0.18; water, 1. Being
near the axis of the great anticlinal the beds must be very
low in the series.*
Parkesburg artesian well in II.
At Parkesburg, in the Chester county valley, an artesian
well was bored, 522' deep, through very steep-dipping lime-
stones near the bottom of the series. Not only sandstone
layers but quicksand layers were passed through, the latter
furnishing water (in one case pretty freely), and being
probably the disintegrated loose grains of beds of calcifer-
ous sandstone which had lost all their soluble lime and
magnesia carbonates by long continued percolation.f
* T, p. 291. Mr. Platt in his Report on Blair county remarks that the dis-
tinct sandstone horizons in No. II, in Nittany valley, make a show in
boulders and fragments on the surface of the country out of all proportion
to their size as beds in the limestone series. But this is a common geological
phenomenon of erosion, well illustrated by the abundance of quartz boulders
left lying on the eroded surface of the hydromica belt of York county, and
the abundance of titaniferous iron ore fragments left lying on the off dip
side of the veins on the demoralized mica gneiss country of Goldsboro' in
N. Carolina. As the surface of the soluble formation is lowered by erosion,
the insoluble massive layers accumulate on the successive surfaces. (Report
T, on Blair Co., p. 60.)
\ Soil, 18'; bastard or sandy limestone, 3'; quicksand, 2'; sandy limestone
growing denser downwards ; quicksand; limestone be"ds increasingly pure
downward, and quite destitute of water veins ; fine yellow sandstone layer
PAKKESBURG ARTESIAN WELL IN NO II. 499
To explain the sand deposits in No. II in Pennsylvania
we must go to northern New York and to the Western
States.
Around the Adirondacks the lowest beds of the Calcifer-
ous sandstone (Ha) of Eaton and Vanuxem are a mixture of
fine grains of sand in a cement of limestone, with a few
fossils converted into chert, 30' ; over these, reddish lime-
stone beds with scattered plates of Cystids, 20'; over these,
clay beds without fossils, but at the top oolitic, 10' ; over
these, red limestones, 15'; over these, clay-lime and sand-
lime beds, with trilobites, 20'; over these, others with brach-
iopod shells; over these, red limestone, with Cystids, fine
enough to polish, 15'; over these, magnesian hydraulic- lime
beds, with few fossils except seaweeds (fucoids) and the
upper layers (20 to 30') blue, cherty, oolitic.
The Chazy (lib) is so similar to the Calciferous under it,
as to make it hard to distinguish them. Emmons calls it
130' thick at Chazy village. Owen recognized it in the St.
Peters sandstone along the banks of the Minnesota river,
where it is a remarkably white mass of transparent quartz
grains, filling depressions in the upper surface of the Calci-
ferous, which of course, had been out of water and eroded.
Some conglomerate beds at the bottom of the Chazy tell
the same story. The Chazy water must have been (in Iowa
at least) very shallow, for there is plenty of oblique bed-
ding. (In Pennsylvania, where these formations are so
vastly thicker no such false or current bedding is reported.)
Its fossils have been badly preserved; but there are often
plenty of seaweed impressions, worm burrows (Scolithus)
and ripple marks; all proofs of shallow or shore water.
In Missouri the sandy character of No. II is illustrated
by the breaking up of the Calciferous (Ha) into two mag-
nesian limestone formations separated by a sandstone forma-
tion. The Upper Limestone interstrated with shale beds and
with free flow of water; limestone beds (without water) all of different
quality, some quite sandy, some with much mica flakes, some almost pure
marble ; fissure and water ; limestone beds as variable in character as those
above, and no sign of essential change, or approach to quartzite at bottom
of well. In the samples submitted to the microscope were noticeable
quartz crystals, mica flakes, crystals of pyrites, of calcite, and of feldspar.
500 GEOLOGICAL SUKVEY OF PENNSYLVANIA.
layers of white chert, with some thin beds of white sandstone,
(often lead bearing), is 200' to 300' thick. The Middle Sand-
stone regularly bedded, and ripple marked, with thin chert
layers full of fossil shells, showing shallow water, is 150'
thick. The Lower Magnesian limestone, thick bedded,
coarsely crystalline, with thick chert beds in some places,
and the chief lead bearing formation of S. Missouri (as in
Blair county, Pa.) carrying also zinc, copper, nickel and
cobalt, disseminated and also concentrated in fissures and
caves, ranges in thickness from 300' to 600'. This must be
a comparatively deep water deposit.
The geology of Blair, Huntingdon, Centre and Clinton
counties and of the Great Valley is greatly elucidated by
the facts above mentioned a thousand miles distant. Not
less so does the geology of the Great Valley in East Ten-
nessee explain our own, for the resemblance is even closer
because the conditions of deposition were more alike.
THE FOSSILS OF NO. II. 501
CHAPTER XLIV.
The fossils of No. II.
In Pennsylvania the Calciferous Ila, is almost non-fossil-
iferous; the Chazy II b is slightly; the Trenton, lie, abund-
antly fossiliferous, its best explored and most remunerative
localities being Bellefonte in Centre and Reedsburg in Mif-
flin counties.
The Calciferous chert beds maybe taken as good evidence
of the abundance of Sponge life.* The oolitic or fish-roe
limestone beds have recently been shown under the micro-
scope to owe their origin to minute rolled fragments of
Bryozoa, which grew as parasites upon the outside of sedent-
ary shells, somewhat in the style of the lichen family of
plants on rocks. Early forms of Coral grew in bundles of
prismatic columns. f The Stonelilies (crinoidea, cystoidea)
all of them more or less stemmed, but not all rooted, have
left their distracted plates in the Calciferous of New York.
The first Star fish forms appear in the Chazy. Brachiopod
shells, especially Lingula, were abundant in all the shallow
waters, but are not found in Pennsylvania. Lamellibranch
shells seem to make their first appearance in the Calciferous
age. Gasteropod shells, both coiled and spired, and some
like Maclurea magna of considerable size, were extremely
abundant near the coasts. Their scarcity in Pennsylvania
argues for depth of watei'4 CepTialopod (cuttle-fish) free
* Sir Wm. Dawson has given us their forms ; see reduced figures of Proto-
spongia on Plate XXVI.
f See Columnaria, on Plate XXVI. Note. The figure of Monticulipora
( Favosites) ly coper don should be removed from this plate to Plate XXXII,
as it is a well recognized Trenton fossil, growing in colonies on the Dela-
ware and Bushkill in Northampton county, and elsewhere. See' Fossil
Dictionary of Pa. p. 421.
J See Plate XXVIII. Note. The Murchisonia milleri on plate XXVII
ought to be removed to plate XXXVI, for it is of Trenton age. The Chazy
Euomphalus catilloides on plate XXX was a large shell, and its cross sec-
tion lines in calcite make spirals on the Great Valley limestones.
502 GEOLOGICAL SURVEY OF PENNSYLVANIA.
XXV/
jfossils tf formation II &. ?!
onocraterion. lesleyi. Prime.
THE FOSSILS OF NO. II. 503
floating shells like Orthoceras primigenium (plate XXIX)
had already existed long enough to develop several species
in the Calciferous, more in the Chazy, and fairly took pos-
session of the Trenton open sea.* Pteropod (wing-footed)
shells of several species existed in the Calciferous sea in
colonies, f The Trilobites began in the Cambrian (or per-
haps Pre- Cambrian age) and must have been abundant in
the whole Lower Silurian age.:}: No higher forms of life
are known, neither crustaceans nor fishes; but it is probable
that they existed and their remains will some day be found,
seeing that large plates of armored fishes like the Devon-
ian Holoptychius (in No. VIII) were discovered three years
ago with Trenton species of shells in Colorado.
It has always been considered a surprising fact that the
keen-sighted and zealous naturalists of Philadelphia and
West Chester have never been able to collect fossils from
the Chester Valley limestones ; nor those of Lancaster and
York from the innumerable limestone outcrops east and
west of the Susquehanna river; although the Calciferous,
Chazy and Trenton age of the rocks was never seriously
called in question, and their connection with the rocks of
the Great Valley was evident. Nor in the Great Valley
itself has any notable collections been made by the college
students of Easton, Bethlehem, Allentown, Carlisle and
Chambersburg. Either the Calciferous and Chazy forma-
tions were laid down on a very deep sea bottom far from
the shores which we know abounded in a great variety of life,
or the remains of plants and animals were afterwards ob-
literated by pressure^ dissolution and partial crystalliza-
tion, which hardly seems probable in view of the fact that
the Trenton rocks in Northampton county are tolerably
* See their chambered structure on plate XXXVII, and a specimen of the
coiled Lituites on that plate ; also a curved Cyrtoceras of Cha/y on plate
XXXI.
t See Primitiagregaria on plate XXIX. But they have not been collected
at Pennsylvanian localities. They became enormously abundant in the
Clinton age ( Va) as may be seen by an inspection of any piece of fossil iron
ore from Danville, Bloomsburg, Orbisonia or Frankstown.
t See Asaphus canalis, on plate XXIX, and other genera on plates XXXI,
XXXVIII, XXXXIII.
504
GEOLOGICAL SURVEY OF PENNSYLVANIA.
a^nes/an limestone)
Jfolla.
Leptasna sericea. (Strophomena sericea,}
Tryblidium ovale, Whitfield, Bull. Amer. Mus. Nat. Hist
Orthis tritonia, Bill. Tryblidium P aoutum, Tryblidium pileolu
Rhynchonella plicifera.,
Rhynchonella altilis. ' (Atrypa
Murchisonm linearis, B Murchisonia milleri
^ I'ennsy
} ton &
,:-Y. Vol.
ilUCaj .
THE FOSSILS OF NO. II. 505
fossiliferous, and Trenton fossils have been collected at
Chambersburg, and also in the narrow up-faulted limestone
belt east of Doylestown in Bucks county.*
Recently, however, an enthusiastic mineralogist, a post
graduate of Haverford College in Delaware county, Mr. M.
B. Stubbs, while hunting for quartz crystals near Hender-
son's station on the Chester Valley railroad, found a con-
siderable number of silicified internal casts of three species
of gasteropod shells and one cephalopod (Orthoceras) in
loose fragments of sandstone lying on the upturned lowest
limestone beds of the valley and therefore presumably from
the slope of the North Valley hill of Chiques quartzite.
The casts (now in the museum of the Acad. Nat. Sciences,
of Philadelphia) are distorted and flattened by pressure,
and their Calciferous age cannot be certified by any specific
characteristics, but few who saw the specimens would
doubt it.
Scolithus linearis has been reported plentiful, with water-
worn pebbles, in a sand pit on the road from Barren Hill to
Chestnut Hill, by Dr. G. M. Stiles of Conshohocken, at
a meeting of the A. N. S. Philadelphia, May 20, 1891. These
are the first discovered in the neighborhood. It is natural
to suppose that they came from the North Valley Hill or
Chiques quartzite, and Prof. Heilprin suggested that the
sand pit is on the line of an abandoned channel of the
Schuylkill river. But it is also possible that the fossils be-
long to some sandstone layer in the Calciferous sandstone
or even Chazy division of II seeing that Scolithus is so
numerous at that horizon in Vermont. Search for Scolithus
in the sandy limestone series itself ought to be made.
It is hard to believe that we are never to know more of
the animal life of the Calciferous and Chazy waters than
from ihe specimen of Maclurea magna (?; and one or two
others mentioned in the reports of Lehigh and Northamp-
ton counties by Prof. Prime. It surely only needs a sys-
*Here Dr. Isaac Lea obtained a few shells from the building stones of a
limekiln many years ago. It is not known if the Trenton has been pre-
served along the Chester county valley, or whether its beds have been con-
verted into Avhite marble.
506 GEOLOGICAL SURVEY OF PENNSYLVANIA.
XXA///I
CLlldstdne (Mayncsian limestone^ \
THE FOSSILS OF NO. II. 507
tematic search for them with the trained eyes of an expert
palaeontologist, or even with the untrained eyes of any col-
lege student whose zeal for natural history equals the sharp-
ness of his youthful vision.*
There is one kind of fossil forms for which special search
should be made, the so called Conodonts , or minute teeth,
most probably of leeches. Worms were abundant in the
shallower parts of the sea, as is shown by tracks and bur-
rows, although the figures of PalceopJiycus on plates XXVI
and XXXI, and Phytopsis on plate XXXII are almost un-
doubted impressions of algge or seaweeds.
Conodonts were first found by Pander in the lowest Silu-
sian rocks of Russia, f Mr. Hinde found them in the dark
*The Calciferous Sandstone Valley of Copake, Millerton and Arnenia, in
Eastern New York, an extension beyond the Hudson of the Great Valley of
Pennsylvania, containing the largest bodies of limonite in the Taconic
region, have yielded numerous specimens of Ophileta, Orthoceras, Cyrto-
ceras, &c., to the keen search of Mr. W. B. Dwight, in 1889. (See Am. Jour-
Sci. Vol. 38, page 150 ; Vol. 39, p. 68. ) He found also in the limestone near
Clove Valley Station, Dutchess county, N. Y. Calciferous fossils, including
the common fucoids, with Ophileta, probably O. complanata ; proving that
the Fishkill belt east of the Hudson is merely a continuation of the Great
Valley limestone belt of Pennsylvania and New Jersey. (Aua. Jour. Sci.
Vol. 39, Jan. 1890, pp. 68, 71.) Also in the so called "Taconic" limestone
belt of Columbia county, N. Y. near Pulver's Station, 2 m. north of Phil-
mont, Mr. L. P. Bishop, in 1887, found gasteropods, crinoids, and a brachio-
pod shell ; and in 1888, six or seven Orthocerata, <&c., Cheteles compacta,
Billings ; Monticulipora lycoperdon, Say ; Orthis testudinaria (?) Dal. ;
and Murchisonia gracilis, in hard limestone, a mile long, 150 yards wide,
completely enclosed in highly metamorphosed schists and slates. (Am.
Jour. Sc. Vol. 39, page 70. The Chatham find of a like nature is recorded
in Vol. 32, pp.438, 1886.)
fMonog. Foss. Fische d. Sil. Syst. 1856. Pander called them fish teeth.
Harley found them in the Ludlow bone bed and referred them to crusta-
ceans. Q. J. G. S. London, 1861, p. 542. C. Moore found them at various
horizons from Silurian up to Permian. Report of Brit. Ass. 1869, p. 375;
and private note in Hinde's "On Conodonts," &c. Q. J. G. S. 1879, p. 351 to
359, with three plates full of figures. C. J. Smith in 1875 found them in
Scotch Low. Garb, rocks. Notes by Young, N. Hist. Soc., Glasgow. Dr.
Newberry found them in Low Carb. rocks of Bedford, Ohio ; and figured
them as the teeth of Mixinoid fishes in Pal. Ohio, Vol. II. In the Hudson
River formation (No. Ill) near Toronto a few compound cone-teeth, mixed
with a great variety of grapholites, corals, worms and brachiopod, gastero-
pod and cephalopod shells, and a few fragments ot a trilobite (Calymene),
are found in thin limestone lenses between micaceous flags and shales ;
there are also some simple spine-like cone-teeth, a form not yet seen except
508 GEOLOGICAL SURVEY OF PENNSYLVANIA.
XX JX
an limestone)
Orthoceras becki, Billings.
C-ttl. Canada. 3Ji .
Orthoceras deparcum, Primitia gregaria, WhitfieM.
(ol 7 mit ; aBe eiyi \ '- n
^ " l /r -i. 7?B51 "V 55
Orthoceras montrealense, Billings. Geol. Canada, 1863
Orthoceras primigenium, Van
M.IIT). fifiazy or MdclleSreat Yall.ey limestone.
SUccopora
fe
Husophycus bllobatus (
Orthis acuminata,
I V
J? Orthis imperator, Billings. Can. Nat. A Geol. Vol
THE FOSSILS OF NO. II. 509
Chazy limestone beds at Greenville on the Ottawa river in
Canada, beds which are largely made up of the small shells
of bivalve crustaceans (Leperditia) with a few small trilo-
bites and gasteropods, for all of which the cone-teeth would
be much too large, since they all belong to the largest
known compound cone-tooth species.
The cone-teeth are very minute shining bodies, single
curved conical teeth with expanded base, or more fre-
quently a row of small cones with a larger one at the end
or in the middle of the row, sometimes with a downward
extended base carrying itself denticles, f They retain their
perfect form and lustre, whether in flag, shale or limestone
beds, although very brittle and easily dissolved by nitric
acid. Most of them are of reddish horn color and translu-
lucent ; rarely of a milky white, and only where weathered.
Those at North Evans are robust and opaque, with a differ-
ent lustre from those in the bituminous shales. Those
from the CJiazy differ from all the rest in the bright glossy
black tint. Microscopic sections show a conical lamellar
structure. Usually found scattered through the rock.
Hinde has one Genesee specimen in which a compressed
group of various forms of teeth and plates have evidently
belonged to one animal, but too much crushed to make out
in the Lower (Cambro) Silurian. While most of the other fossils are in the
limestone beds the cone-teeth are generally found in the shales.
In Upper Hamilton lime-shales (YIIIc) finely exposed at North Evans,
on the Lake Erie shore in New York State, cone-teeth are numerous, and
one particular limestone bed is so filled with their fragments as to be called
by Hinde the Conodont bed; |" to 3" thick; traceable for some distance;
dark, sub-crystalline, with green particles, and pyrite crystals ; holding
also crinoid stem fragments, fish bones and plates, Ptycodus teeth of Pan-
der, but neither crustaceans nor gasteropods. The cone-teeth can only be
detected with a good lens, and on weathered' surfaces. A. few cone-teeth as-
sociated with fish plates and teeth have been found in a thin Hamilton lime
bed at Arkona, Lambton county, Ontario.
In black Genessee shale cone-teeth have been found by Hinde at Kettle
creek and Bear creek, Canada West ; in fragments on the north shore of
Lake Erie ; in the fine section at North Evans, N. Y. ; and at Louisville,
Ky. ; mixed with a small number of Lycopod plant spores, broken plants,
a few Lingulas, Discinas and Aviculas, and Palceoniscus fish scales ; but no
forms to which the cone-teeth could easily belong.
The Lower Carboniferous black shales in which Newberry's conodonts
occur show nothing else than plants and ganoid fish scales.
fFor other forms see Hinde's description on p. 354 and his plate figures.
510 GEOLOGICAL SURVEY OF PENNSYLVANIA.
Mill. CAazy orlMiddle 9reat Yalley limestone.
Orthepwnoides Orthis pervetus. Conrad
R.554. ^5^ Hall. 1.6.5.
Kaphistoma striatuu
.-"-^>r"- Rapliistom*
planrstria.
FOSSILS OF THE CALCIFEROUS, lid. 511
their arrangement. Huxley saw a resemblance to the hag
fish (Myxine), but could indicate no living fish with a simi-
lar assemblage of teeth and plates. Owen at first suggested
that they might possibly be toothed crustaceous claws ; af-
terwards, that they might rather be spines, booklets, den-
ticles of naked shell-fish or worms. They seem to have
been the only preservable part of the animal whatever it
was ; and they may possibly be the only evidence we have
for the early existence of the soft circle-mouthed family of
fishes. Dr. Woodward suggested that they might be the
tongue-armor of the shell-less gasteropods (Nudibran-
chiata) which have therefore never been found in the rocks.*
Fossils of tJie Calciferous, Ila.
Some of the most characteristic and most widely dis-
tributed forms of this formation, are, according to S. A.
Miller's N. A. Geology and Palaeontology, f Ophileta com-
planata, Ophileta U7iiangularis, Holopea turgida^ Hol-
opea dilicula, and Pleurotomaria primigenium.
From the Potsdam ascend into this Calciferous division,
Pleurotomaria canadensis and Leptcena barabuensis.
The following have been assigned to this formation (or
to supposed equivalents of it in the Quebec group) Pluro-
tomaria calcifera, Pleurotomaria postumia, Helicotoma
perstriata, Maclurea matutina, Maclurea sordida, Eccy-
liomphalus canadensis, Camarella calcifera, Lingulella
mantelll, Lingulella iren.e, Amphion salteri, Bathyurus
cordai, Bathyurus conicus, and Asaphus canalis; but the
identifications of Quebec and Calciferous strata are always
to be distrusted.
Fossils of tlte Quebec group.
Of these the less said the better until the controversy over
the Quebec group has been settled. The species Lingulepis
maera, mlnuta, andmanticula, Acroteta gemma, Agnostus
communis, bidens, and neon, Crepiceplialus Tiaguei, and
*Q. J. G. S. XXXV, p. 389.
t Second Edition, Cincinnati, 1889, page 34.
512 GEOLOGICAL SURVEY OF PENNSYLVANIA.
XXXf
Orthocerata figured by Em i Orthoceras multillneatum. Calymene
FOSSILS OF THE CHAZY, II b. 513
unisulcatus are confidently assigned to equivalents of the
Quebec group in the Rocky Mountains. The family of
Graptolites is said to reach its highest development in the
Quebec group. Thirty genera and 170 species of Grapto-
lites have been named thus far in North American rocks.
Maclurea atlantica and Asaphus canalis are said to range
up through the Chazy and higher.*
Fossils of the Chazy, 11 b.
The characteristic form of this age is considered to be
the line whorl-shell Maclurea magna. With this are as-
sociated others which continued to live even into Hudson
River times : Stropliomena alternata, and incrassata,
Orthis perveta, Leperditia canadensis, loucTcana, and
amygdalina, Orthoceras multicameratum, and Mlineatum
and the lamellibranch shell Modiolopsis nasuta. Scolithus
is abundant in the formation as recognized in some regions;
and Lingulepis morsel is described from the St. Peter's
sandstone of the west.f
Fossils of the Blac'K River limestone, II c (in part).
These were defined by Vanuxem in 1842 in the bluffs of
Birdseye and Trenton beds at Boonville, N. Y., but there
has always been a doubt of the propriety of separating the
Black river and Birdseye beds and giving two names to what
seems like one formation, distinguished on the Black river
by its abundance of Cephalopod shells, and on the Mohawk
river by an abundance of the Birdseye fucoid Phylopsis
tubulosa.
The vast and varied population of the sea at the begin-
ning of the Trenton age, as shown in the Black river beds,
produced by its decay the dark color of the rocks, the
black marbles of Vermont and Pennsylvania. Many of
the species died out however before the normal Trenton
limestones were deposited. But the family of straight
* This paragraph is a condensation ot statements made by S. A. Miller on
his page 35.
t S. A. Miller, 1889, p. 38.
33
514 GEOLOGICAL SURVEY OF PENNSYLVANIA.
Phytopsia tubulosa P (Fucoidet demittu*.) V
3$ircLei/& and ^Blaclc^&ivw*:
</
Tetradinmfibratum.Bafford. American Journal of Scil
FOSSILS OF THE BLACK RIVER LIMESTONE, II C. 515
shell cephalopods (OrtJioceras] reached its climax now, not
only as to the number of its species, but as to the size of
its individuals, some of them having had tapering cham-
bered shells ten feet long and twelve inches in diameter at
the head. The allied Cyrtoceras and Endoceras were
highly developed ; and the genera Oomphoceras, Phrag-
moceras and Gyroceras brought their species into the field.*
Corals also were abundant in places, and petroleum
exudes from their fossil forms when broken, as at Mont-
morency in Canada, f
Fossils of the Birdseye limestone, lie (in part).
The charactersstic fossil of the Birdseye limestone is a
vertical, cylindrical, sub-cylindrical, angular or compressed
stem of a marine plant, branched, connected, forking, radiat-
ing, looped, etc. etc. with an internal fibrous structure, as
shown in Hall's figures of 1843, Vol. 1, Pal. N. Y. plates
8 and 9, which seem to exclude the possibility of these
markings being casts of worm burrows, as insisted on by
Salter and Etheridge, and so tabulated by Bigsby in his
Thesaurus Siluricus.:}:
* Where were the feeding grounds of these hugh floating walking-canes of
stone, ballasted below and buoyed by their air-filled chambers above, with
their great eyes looking for prey, and their long arms spread out at the sur-
face of the water to seize and bring it to their mouths? Requiring but
little depth of water they probably haunted the shores of the then conti-
nents and Avere supplied with abundant provender by the scum of trilobites
which floated like themselves as water bugs upon the waves. The brachio-
pod and lamellibranch shells were no doubt safe from their attacks ; yet the
shore waters must have been their most profitable haunts ; and if so we can
comprehend the vast abundance of their remains in Northern New York
and their comparative absence from the rocks of Pennsylvania. Or, were
they endowed with sails like the modern nautilus, and made voyages before
the wind ? It is a pity that the rocks have preserved for us no lithographs
of their curiously unknown soft heads and bodies.
fThe same thing happens when the corals of the Niagara rocks of New
York are broken out. Such facts establish the animal origin of the older
and more fetid petroleums ; the later and sweeter oils having come from the
chemical change of the cellular tissue of marine vegetation, as shown by
Lesquereux.
J See what is said in Chap. XVII on Scolithus, beginning page 287 above.
See also reduced figures of the Phylopsis tubulosa given at the top of plate
XXXII. Hall's figures will be reproduced in the Appendix to Fossil Dic-
tionary.
516 GEOLOGICAL SURVEY OF PENNSYLVANIA.
xxxm
and attack jtive
MJTc. ^frmton, i
(IW., Pl. N. V Conularia gracilis Conularia papillata. Atrypa exi R ua
Orthis aequivalviB. Hall Orthis bellara?osa. Conrad, Orthis lynx, ( Deltfiytif lynx ; ft
JjB^MI fl ft ^^^ ^^^ ^f,
OrthiBpectinella, Conrad. Ann.Rt. N. Y.1840. Bl
Orthifl subquadrata, Hall. Pal. N. Y. Vol. 1. 1847. Tren- II c, <^f.C
* 5-r-. *
FOSSILS OF THE TRENTON LIMESTONE, II C. 517
fossils of the Trenton limestone II c.
This famous formation was first described by Emmons in
1842. At Trenton Falls in New York it shows 100 feet of
very fossiliferous, dark, fine-grained, thin-bedded limestone
layers below, separated by black shales, passing up into
coarse grey, thick, less fossiliferous beds at the top. At
Cliazy it is 400' thick. In middle Pennsylvania it is 1000'
and 1200' thick. In middle Tennessee only 500', it is in
eastern Tennessee 1100' thick. In Canada it is 600' thick at
Montreal, 750' further west, but only 50' around lake Mich-
igan. In Iowa and Illinois its lower blue division, 120' thick,
is capped by the lead and zinc-bearing dolomitic layers of
Galena, 150' thick. In Missouri it is 400'.
Its wide distribution attests an open and moderately deep
sea deposit. Its wealth of life is exceptionally great.
Graptolites and Trilobites were on the decline; but Crinoids,
Cystideans, Brachiopods, Corals, Gasteropods and Lamelli-
branchs were on the increase.*
* C. A. Miller's Geol. and Pal. N. Amer. 1889, p. 41. I cannot do better
than extract the interesting paragraphs from this indespensable guide to the
student of fossils which follow on pages 41, 42 :
" Receptaculites oweni is peculiar to and characteristic of the Galena di-
vision of this Group, and it is usually accompanied with Lingula quadrata,
Murchisonia major, -Fusispira elongata, and other characteristic species.
The species most characteristic of the Trenton Group, and which may be
relied upon as determining its age wherever they occur, are Orthis tricen-
aria, found in New York, Canada, Kentucky, Missouri, and Nevada; Ort/ti
pectinella, found in New York, Canada and Kentucky; Cyrtolites comprca-
sus, iound in New York, Canada, Wisconsin and Minnesota; Hybocriinis
tumid us, H. conicus, Amygdalocystites florealis, A. radiatus, Blastoidos
crinus carcharidens, found at Ottawa, Canada, and High Bridge, Kentucky;
Leper ditiafabulites and Conularia quadrata, found in New York, Canada
and Kentucky; and Orthis borealis, found in Canada, Wisconsin, Minne-
sota and Kentucky. The genus Amygdalocystites has a wide geographical
distribution, though a rare fossil in every locality, and, so far as known, is
confined to this Group. Other characteristic species are Bythotrephis suc-
culens, Monticulipora lycoperdon, Schizocrinus nodosus, Stictopora ele-
gantula, Orthis bellarugosa, O. cequivalvis, Trochonema umbilicatum,
Subulites elongatus, and Helicotoma, planulata.
" There are numerous species which continued to live until the Hudson
River age, and are, therefore, common to three Groups, as Strophomena al
ternata, 8. rhomboidalis, Leptena sericea, Zygospira modesta, Rynchonella
capax, Calymene callicephala, Asaphus gigas, and Ceraurus pleurezanthe-
518
GEOLOGICAL SURVEY OF PENNSYLVANIA.
~ -* Vol.1, PI. Vlt.
Strophomena (Leptcena) alternistrlata, Hall, Pal. N. Y
FOSSILS OF THE TRENTON LIMESTONE, II C. 519
The Trenton fossils have been in Pennsylvania best
studied at Bellefonte in Centre county. Strata occur
'''composed almost entirely of fossil remains," all of
them recognized Trenton forms. Prof. Ewing, late of the
State College in Centre county, adds in his report (embodied
mus. Sucli species are usually quite variable in form and size, and seem to
have changed to su^t the conditions of their habitat, and also, in accordance
with the theory of evolution, to have reached the climax of development,
and subsequently gradually declined. Strophomena rhomboidalis occurs
in Trenton, Utica Slate, Hudson River, Clinton, Niagara, Lower Helderberg,
Upper Helderberg, Hamilton, Chemung, Waverly, Burlington and Keokuk
groups. Its vertical range exceeds that of any other species in any of the
rocks of the known world, and its geographical distribution is common to
every continent where strata of these ages have been studied and described.
The varietal forms have been called S. tenuistriata from the Lower Silurian,
S. depressa from the Upper Silurian, and S. rhomboidalis from the Devon-
ian and Subcarboniferous. The Lower Silurian specimens are usually
smaller, and have fewer concentric wrinkles over the visceral region than
those from the Upper Silurian and Devonian, while the length of the front
and lateral margins from the geniculation is usually greater in the Upper
Silurian than.it is in the Lower Silurian, Devonian or Subcarboniferous
specimens ; but these differences are not so constant as to form inflexible
characters, and hence it is that many of the learned and better palaeonto-
logists have classed them all together under the first and oldest specific
name. The various forms which Strophomena alternata assume in the same
group of rocks are wonderful; the radiating striae differ in size and number,
the hinge line is sometimes longer and at other times shorter than the great-
est width of the shell. The shells are sometimes much longer than wide,
and at other times as much shorter. The lateral sides are sometimes straight,
and at other times rounded. Some shells are nearly flat, others are deeply
concave on the dorsal side and highly convex on the ventral. Age in some
specimens appears to have materially thickened the shells, and preserved
strong imbricating lines of growth, while in other cases we have much larger
shells that are very thin and destitute of imbrications. Like differences may
be distinguished in other species having great vertical distribution, as in
Rhynchonella capax and Zygospira modesta.
" The rocks of this Group are composed almost entirely of remains of the
hard parts of animals that swarmed in the seas of that age. Some shells are
preserved in good condition, but generally the comminuted fragments are
held together by lime cement, forming the limestone strata, leaving well-
preserved specimens to be found only in the shaly partings. It is common
to flnd that one animal has grown upon another, as a Lichenocrinus upon a
brachiopod, and a bryozoan upon the former, under such circumstances as
to show the shell was at the bottom of the ocean during the growth of the
Lichenocrinus, and that the latter must have ceased to grow before the bry-
ozoan attached. From this we infer the clearness of the water, for otherwise
mud would have intervened; and we also infer a slow deposition of materials ;
for the lives of two animals transpired before the deposit was sufficient to
cover a thin shell. There is no evidence of any difference between the tem-
perature of the water then and now, nor between the climate then and now.
520 GEOLOGICAL SURVEY OF PENNSYLVANIA.
X.XVV
M. lie.
Modiolop.1. trentonensi., Hall, Modiolopsis meyeri, Bill; Modiolopnis . maia, Modiolopais carinata,
FOSSILS OF THE TRENTON LIMESTONE, II C. 521
in Report T4, p. 424) the following list: Schizocrinus
nodosus (stems of this stone lily); Streptelasma cornicu-
lum ; OrtMs testudinaria (very common above); OrtMs
tricenaria; OrtMs pectinalinea ? ; OrtMs lynx; Ortlus
subequalis ; Strophomena alternate, (very common above);
Leptcena sericea (common above); Lingula curia (one);
Pleurotomaria lenticular is, arid another species ; Mur-
cTiisonia gracilis ; Leperditia ?; Trinucleus concentri-
cus ; Calymene ?; Clienteles ly coper don.
Mr. C. E. Hall in his collection lists published in the
Catalogue of the Museum of the Survey, O3, 1889, page
177 et seq., adds to the above, numerous Bryozoa ; Sticlopora
acuta / fragments of Tentaculites ; Ceramopora f; frag-
ments of Trematopora ; Monticulipora pulchella ; Bey-
ricMa (numerous); Zygospir a modes ta ; CalymenebecTcii ;
an Orthoceras (encrusted with bryozoans); SpirorMs (num-
erous); a Better ophon. Again on p. 183, Edmondia sub-
truncata; Murchisonia gracilis; Cypricardites sub-
truncatus ; Camarella ambigua ; Camarella liemiplicata ;
Palceophycus simplex (in fair condition); Buthotrephis
succulens ; Asaphus obtusus ; a colony of Lept(Eiia sericea
on one slab; an lllcenus ; Cypricardites ventricosus ;
Plumulites jamesii ; Pholidops trentonensis ; Geraurus
pleurexantJiemus ; Atrypa altilis.
In Fellows' collections for C. E. Hall in Trenton layers
on the Little Juniata at Tyrone Forge (List in O3, p. 189),
appear, with many of the above, these also : Rliynchoii-
ella cap ax ; EscTiaropora (Philodictya) recta ; Retepora ;
Cornulites Jlexuosus ; and Stictopora elegantula.
Reedsville, in Mifflin county, is another excellent collect-
ing ground for Trenton fossils, where many specimens of
Homalonotus trentonensis were got. (See list in O3, p.
179.) Among other forms are noticed OrtJiis costatus ; En-
doceras proteiforme ; Lingula oblong a ; Bathyurus ex-
tans ; Modiolopsis faba ; and RapTiistoma lenticular is.
The two last were collected also near Martinsburg in Mor-
rison's Cove in Blair county. (O3, p. 181.)
Collections were also made at Belleville, in Mifflin county,
522 GEOLOGICAL SURVEY OF PENNSYLVANIA.
Holopea veutrioosa. (Hall, Pal. N. Y.V. Holopea paludlniformis. (Hal! Macrocheilus subcostatus P Ow
FOSSILS OF THE TRENTON LIMESTONE, II C. 523
by Mr. Billin, at Campbell's quarry in Trenton limestone
top beds. (O3, 190.)
I have found colonies of Trenton brachiopod shells cov-
ering slabs of limestone in the Nippenose and Oval Mus-
quito valleys of Lycoming county.
The Trenton belt in Northampton county is rich in cri-
noidal stems, with OrtJiis pectinella, and Atrypa recticu-
laris at Martin's creek on the Delaware, and in the numer-
ous quarries along the line crossing the Bushkill. See
Prof. Prime's Report, D3, Vol. 1, already mentioned in a
preceding chapter.
I have no doubt that a shrewd and zealous collector would
reap a plentiful harvest by traversing the center line of
Black Log valley in Huntingdon county. Good collections
could be'made in Friend's and Milligan's coves in Bedford,
and perhaps around the edges of the McConnellsburg cove,
and along Path and Horse valleys in Fulton. Trenton fos-
sils have been found at Chambersburg in Franklin.
624 GEOLOGICAL SURVEY OF PENNSYLVANIA.
Lituites farnworthl, Billings. Pal. Fow. Vol. 1, 1861 Oncoceras coMtrlcttun.
Ormoceras tenuifllum. Hall, PaL N. Y. Vol. 1, 1849,
~" -':
TSTO. III. UTICA AND HUDSON RIVER. 525
CHAPTER XLV.
Formation No, III. Utica and Hudson River slate.
The age of limestone which has been described in the
preceding chapters, was followed by an age of slate.
Primeval rivers which had been pouring for thousands of
years their lime and magnesian waters, nearly pure of mud,
into the Appalachian sea, thenceforward for other thou-
sands of years flowed turbid with clays, which settled to
the bottom, blackened with the decomposition of innumer-
able animal remains mostly of microscopic size. At first
the layers of clay were not continuous ; thin layers of lime-
stone, or rather lime shale were deposited between them ;
but these gradually became fewer and fewer, and in the
end an almost continuous deposit of very slightly calcareous
mud went on. At long intervals and apparently only in
certain parts of the sea bottom, layers of very muddy lime-
stone, 3 or 4 feet thick, were made. Toward the close of
the age another change took place in the character of the
stuff brought down by the rivers ; their mud became
coarser by an admixture of fine sand ; the sand increased
in size and quantity ; and finally became the prevailing
sediment.
Knowing so little of the conditions which then prevailed
on the globe, so little of the character of that primeval sea,
and of the continent whose rivers furnished it with stuff
by which it was at last filled up, it seems audacious to at-
tempt to sketch even in general terms the sequence of
events, a picture of these operations of Palaeozoic history ;
and every sentence of the sketch is liable to error. For no
explanation can be given of the changes by land and sea
which produced so radical a change of deposits as that
which stares the geologist in the face wherever he crosses
the Great Valley. He sees 6000 feet of the slate formation
526
GEOLOGICAL SURVEY OF PENNSYLVANIA.
XXX vnt
NO. III. UTICA AND HUDSON RIVER. 527
No. Ill, in Northampton and Lehigh counties, piled upon
3000' of the limestone formation No. II ; but it is left to
his imagination to conjecture what stopped the deposits of
limestone and started the deposits of slate. He knows
nothing of the depth of the sea at any stage of that his-
tory.* He knows nothing of the evenness or unevenness
of its floor. He cannot tell at what distance lay the con-
tinental shores from which issued the mighty rivers which
furnished the sea with its sediments ; nor how the general
level of the ocean rose or fell upon those shores, now re-
moving them to a greater distance, or now bringing them
nearer. He only sees that the bottom slates of Formation
No. Ill (Utica slate), were precipitated as black mud ; and
that the rest of the 6000 feet (Hudson River slate) is made
up of thin layers of fine shale, of various tints of gray,
with a few layers of impure limestone in Dauphin and
Cumberland counties, a remarkable set of gravel beds in
Lehigh county, and a whole series of roofing slates, with
coarser sandy beds, toward the top.
One extraordinary part of this obscure history rivets our
attention.
Taking the two formations together, that is, measuring
the whole thickness of their sediments from the bottom of
the limestone to the top of the slate, on the Lehigh and
Delaware rivers, we have between seven and eight thousand
feet of strata. Doing the same in Nittany valley on the
upper Juniata, we have the same amount. And yet meas-
uring the two formations separately we see that while No.
II is say 2000' on the Lehigh and over 6000' on the Ju-
niata, No. Ill is 6000' on the Lehigh and only 1000 on the
Juniata. Incautious geologists would pass lightly over so
wonderful a phenomenon by simply pronouncing that talis-
manic word non-conformability; or, perhaps, giving it a
little more consideration, would content themselves with
*The Cincinnati (Hudson river) shale and limestone beds are supposed
to have been deposited in shallow water. This is the opinion of Dr. New-
berry, Prof. Shaler and Prof. J. F. James. Mr. N. W. Perry's article in the
American Naturalist, Dec. 1889, illustrated with phototypes of rain marks,
ripple marks and mud cracks of the most characteristic kind, explains
them as made over the gradually sinking bottom of a shallow sea.
528 GEOLOGICAL SURVEY OF PENNSYLVANIA.
Constellaria(Stellipora)antheloidea. Monticulipora James:
Jtid. 1882. f/ 9 .5. PL XI
Monticulipora frondosa, D'Orbigny Colleti
i I IP
NO. III. UTICA AND HUDSON RIVER. 529
suggesting some oscillation of the sea bottom, without being
able to explain how that oscillation could produce the ef-
fect. Both formations spread throughout the United States.
But their thickness in Pennsylvania is diminished to one-
third in the western States. There continental source would
therefore seem to have been in the far east. Seeing that
mud is the usual contribution of rivers to the sea, and that
therefore the slate Formation No. Ill would probably be
thicker at the east than at the west, one might be inclined
to regard the limestone formation, which is so much thicker
in Middle Pennsylvania than in the Great Valley, as a pro-
duct of the sea itself, and not of the rivers of a bordering
though perhaps distant continent. Such in fact is the con-
viction of many, some of whom regard all limestone beds as
chemical deposits from standing water ; while others re-
gard them as made up entirely of the solid parts of ani-
mals inhabiting the sea, dying in it and sinking to the bot-
tom. But reasons have been given in a preceding chapter
for rejecting both these views ; at all events without in-
cluding the action of inflowing river sediments. The fact
is that our science is as yet at fault in its discussion of
this and other kindred subjects.
The shape and size of the Appalachian sea at the close
of the limestone age were undoubtedly greatly modified by
physical movements in the crust of the earth supposed to
be then going on in eastern New York along the Hudson
and Mohawk valleys. Around the escarpment of the Cats-
kill mountains the slate formation No. Ill, and the suc-
ceeding formations No. IV and No. V are so thin as
scarcely to be visible ; and this can hardly be explained on
any other hypothesis than that of an upward movement of
the land, temporary or otherwise, and the contraction of
the eastern and northern borders of the sea. Such a move-
ment in that region could hardly have taken place without
a more or less general elevation of the sea bottom, and a
shallowing of its water-basin, bringing the top of its lime-
stone deposits nearer to the surface of the water. This
may perhaps set us on the track of a future satisfactory
explanation of the wonderful change from reputed deep-
34
630 GEOLOGICAL SURVEY OF PENNSYLVANIA.
. Ill a, ^iitiaz awi IRb,
JU.&i'tX.ttJ&fl
ius. juveni. (Hall
1>.
__ 7al.Oh, B .Val.Z.
Olyptocrinus decadactylue.
omatopora densum. (Syringoitroma^ ^\j/ffifa ^ omntopora (Aleeto) frondosa. Nicholo. (Av
III a.
Graptolithus divaricatus. Hall. Pal. N. Y., Vol. HI,
Graptolith
>v<
I. in* Graptolithua gncilit. Hall. Pal. N. Y., Vol. Ill, p.
jli. Ilr.ll. Canada Rt., 1858, Pal., N. Y
NO. III. UTICA AND HUDSON RIVER. 531
sea limestone deposits to reputed shallow-water shale and
slate deposits. But it still leaves to he considered the im-
portant fact that 6000 feet of the shale formation No. Ill
was laid down in reputed shallow water. If we adopt that
explanation we must conclude either that a shallow sea can
be nevertheless as much as 6000 feet deep, and still receive
near shore deposits ; or else that any rapid upward move-
ment at the end of the limestone age must have lasted but
a. comparatively short time, and was followed by a long
slow downward movement of the sea bottom to receive the
6000 feet of slate. It will be seen hereaftei*, in describing
the successive formations from No. IV to No. XVII, that
such a downward movement did in fact take place, contin-
uously, or by successive instalments, and at varying rates,
through the whole series of Palaeozoic ages to the end of
the Coal age.
The darkness which covers this whole subject is still further
increased by our insufficient knowledge of the effects pro-
duced long afterwards upon the condition of the Palaeozoic
formations by the great earth movements in the Mesozoic
ages ; for many of the phenomena usually considered as
falling under the head of originalnon-conforinability\&.\v
been produced by the crushing and faulting of formations
beneath, against and over each other. It has been rather
too rashly asserted that the limestone beds of No. II in
Pennsylvania along the Great Valley were plicated and
lifted out of water, and subjected to the erosion of atmos-
pheric agencies, and then resubmerged and covered over
non-con formally by the slate beds of No. III. The old and
recent surveys of the Great Valley show that there is no
sufficient ground for such an assertion. On the contrary,
wherever the contact of the upper beds of II with the lower
beds of III are exposed to observation they are seen to
overlie each other in uninterrupted sequence as if they
were beds of one formation. Along the middle line of the
Great Valley however, from the Delaware to the Susque-
hanna, the contact is obscured by the crushed, folded and
overturned condition of the rocks. But from the Susque-
hanna to the Potomac the contact line can be studied with
GEOLOGICAL SURVEY OF PENNSYLVANIA.
JfoJUI&tuxt
XXXXJ.
Diplograptus (Graptolithus) anpistifoiius, Diplograptus (Graptolithui) spinulosns.
""" 1 H *Dal!. D1 PloPaptus (Graptolithus) marcldus **^lfcr Diplograptus (Graptolithus) whltfleldi.
-" K A Till', Diplograptns prUUs.
Orptolithu multifaMiculat Thamnograptus capillaris. Graptolithua divergen
Ehynchonella capax ( Atrypa capo, ; Conrad. . Ehynchonella P modesta, Rhynchonella antlcosti
(? ^"""y"") neglect*
ahecuba, Bill strophomena (aJ(rna(a, Mr.) nauta
IB ::: ....... I
J *
3F **
a IW3.. "^llBfc
NO. III. UTICA AND HUDSON RIVER. 533
comparative ease ; and in the bends of Conodoguinet creek
the upper limestones of No. II are seen changing, by a sys-
tem of alternations nearly a thousand feet thick, into the
lower beds of No. III. These alternations of thin lime-
stones, lime shales and clay shales are called the passage
beds of No. II and III ; and they occupy in that region the
place in the series which the Utica shale division of No.
Ill occupies elsewhere.
In Franklin county the superposition of No. Ill on No.
II can be studied to great advantage by means of the 'four
anticlinal belts of II sustaining synclinal belts of III, as
more fully described in Chapter XXII, page 288, above. In
Berks county the same fact is made clear in another way,
as the limestone belt west of the Schuylkill is set with
parallel synclinal slate ridges lying in long narrow troughs
of the limestone. In Lehigh county we have the best of
these exhibitions in Huckleberry ridge. Here the front
edge of the slate belt at Foglesville runs forward 6 miles to
a sharp point within 2 miles of the Lehigh river at Allen-
town, while a great cove of limestone behind it encloses the
Ironton mines.* All these isolated streaks and spurs of
the slate No. Ill in the limestone valley of No. II are so
many separate proofs that the slate formation overlies
regularly, and conformably the limestone formation No. II.
This condition of things becomes still plainer when we
leave the Great Valley to study the two formations in the
interior valleys of Middle Pennsylvania.
Path valley in Franklin county serves as a link of con-
nection between the interior mountain country and the
Great Valley, into which Path valley opens at its southern
end. The McConnellsburg cove in Fulton county is the
first completely isolated uprise of the limestone back of the
North mountain and is surrounded by a border of overlying
slate. Horse valley in Perry county is almost entirely
floored with slate. A border of slate entirely surrounds the
central limestone floor of KisJiicoquiUis valley with its
three parallel slate prongs towards the east. A similar
border of No. Ill slate entirely surrounds the irregular
*See description in Chapter XXX, page 347, above.
534 GEOLOGICAL SURVEY OF PENNSYLVANIA.
. Ilia, fyfjUCd, and III I, ^i
Lyrodesma poststriatum. ( Xueulana pothriata. ) E.
"Uo' T r r^>. ! " 'i o '" yNw- 1 -' 2
Ct ^>^<^.
110^^4
NO. III. UTICA AND HUDSON RIVER. 535
limestone area of Penn, Brush, Nittany, Sinking Spring,
Canoe and Morrison valleys. Similar slate rings surround
the limestone of Nippenose and Mosquito valleys in Ly-
coming, and Friends and Milligari's coves in Bedford.
All these outcrops of No. Ill show the slate to be about
1000 feet thick, resting conformably upon the top beds of
Trenton limestone, and descending conformably beneath the
surrounding sandstone mountains of No. IV. It may be af-
firmed with confidence that in no part of the world is there
a more satisfactory exhibition of regular conformity in the
superposition of one great formation upon another over an
extensive region.
The attention of the reader is directed to the fact that all
the valleys floored with No. II and surrounded by a contin-
uous outcrop of No. Ill, as described above, are in counties
of middle Pennsylvania lying west of the Susquehanna
river; for neither the limestone nor the slate reaches the
present surface of the State anywhere east of the Susque-
hanna river, except in the Great Valley. When No. Ill
goes down for the last time along the south foot of the Bald
Eagle mountain in Centre county, and Dunnings mountain
in Blair county, it does not rise again until we reach Cin-
cinnati on the Ohio river, where the slare formation has re-
ceived from the Ohio geologists the name of the Cincinnati
group. Its northern outcrop, exposed in Canada, but con-
cealed beneath the waters of Lake Ontario, appears at the
western foot of the Adirondack mountains in northern New
York, and in the lower Mohawk valley, where it received
nearly fifty years ago the name Loraine s7ial.es and Utica
slate. From Albany south it was named the Hudson River
slate, a name by which it has been commonly known in
American geology, and by which it has been habitually
designated in all the reports of the Pennsylvania Geological
Survey since 1874. The name of Naslimlle group was given
to it by the Geological Survey of Tennessee, around the
central area of which its outcrop describes a great ring.
Along the southern extensions of its outcrop No. Ill
exhibits a remarkable change of color soon after passing
out of Pennsylvania into Virginia, becoming so red by ex-
536 GEOLOGICAL SURVEY OF PENNSYLVANIA.
F777
S.Itta. Qttica, and .Ulb.^&usUon riveiiconJM.
Modiolopsis anodontoides
Cyrtolites ornatus. Rogers, page 821, fig. 61
Bucania rugos Cyclonema bilix
hisonia turricula. Murchisonia gracilts. Murchisonia gracilis
f.o -.-rz. -' ~~\ in t,.
EM.
Microdiscuo quadricostatus,
Proetus spurlocki Proetus parviuscu
Menocephalus globosus, "' ''^~
Triarthrus glaber, Triarthrus spinosu
NO. III. UTICA AND HUDSON RIVER. 537
posure to the atmosphere as to give the slopes of the mount-
ains into which it sinks a reddish soil; indicating a much
larger percentage of disseminated iron pyrites throughout
the mass than in Pennsylvania. From the Hudson
river northward through Vermont into Canada the slate
beds also exhibit an extra percentage of sulphide of iron;
but in that region the pyrites instead of being distributed
microscopically through the slate is concentrated into mil-
lions of separate beautifully perfect individual cubes, of all
sizes from a half inch down to the tenth of an inch. Long
exposed surfaces of these Vermont slates are pitted with
square holes from which the crystals of pyrites have been re-
moved by solution. In the roofing slate belt of eastern Penn-
sylvania such crystals are frequently seen; and some of the
beds are rendered worthless to the quarrymen by the quan-
tity of microscopic pyrites which they contain; others seem
to be almost perfectly free from this noxious adulteration.
One of the sources of the pyrites was no doubt an infu-
sion of sulphate of iron poured into the sea by primeval
rivers. But we must ascribe the special abundance of py-
rites in certain parts of the formation, in certain beds, and
at certain localities, to some more restricted cause ; and we
know of no other special cause than that of the secretion
of sulphur in the tissues of animals and plants, especially
of sea weed vegetation. The accumulation of sea weed on
a shore will always furnish a considerable amount of iron
pyrites to the shore sands ; and consequently to the deposits
of the sea bottom in the neighborhood. We have a right
to suppose that the general distribution of iron pyrites
through the slates of No. Ill testify to the existence of
marine plants in great abundance in that age, even were
no traces of the existence of such plants preserved as col-
ored impressions on the surface of the slates. We are,
however, not left to any vague speculation on this subject.
The remains of plants have been collected from the New
York outcrop of No. Ill and described and figured by Pro-
fessor Hall under the names Sphenothallus , Buthotrephis,
and Pal&opJiycus* It is true that other imprints on the
^Palaeontology of New York, Vol. 1, 1847, pi. 68, 69 and 70.
538 GEOLOGICAL SURVEY OF PENNSYLVANIA.
slates have been described and figured as plants which are
now believed with good reason to be merely markings left
by wriggling worms, crawling crustaceans, and locomotive
shellfish ; yet this does not invalidate the plant character
of the remainder ; and we cannot imagine a sea inhabited
by animals, even of the lowest grade, without the co-exist-
ence of a world of marine plant life on which these ani-
mals could feed.
One of the most curious facts connected with the expo-
sures of No. Ill is the occurrence in some places of streaks
and nuts of a sort of anthracite coal. Such nuts of coal, as
large as a hen's egg, have been picked out from between the
slates of No. Ill on the side of Cove mountain in Franklin
county. Their composition will be given in another place.
Their origin is quite unknown ; they have no connection
whatever with beds of coal ; they have not been transported,
but were made in the place where they were found ; they
are disconnected also from each other ; they appear to be
concretions or small accumulations of nearly pure carbon ;
and their genesis is probably connected in some manner
with that general distribution of carbon through the slate-
mud which has given so many of the beds of the formation
a black or blue-black color.
Besides the markings made by animals and the impres-
sions left by plants there is a third kind of fossil forms in
No. Ill of the greatest interest to the geologist. Some of
the slate beds are made up of innumerable paper-like layers
of slate connected together ; and on the surface of these
black films of mud appear millions of markings resembling
scattered straw, and bits of black thread. Most of them
are fragments of some living organisms which at first sight
would be taken for the thin stems of plants. Others are
arranged together in regular forms radiating from a center
or with a center line forked at both ends, the end-forks
forking again. Some of these kinds have all their forks
connected by a delicate almost invisible membrane, like an
old umbrella with its ribs sticking out beyond the edge of
the silk. Others are like oval leaves pointed at both ends
and with radiating nerves, the ends of which project all
NO. III. UTICA AND HUDSON RIVER. 539
round beyond the edge of the leaf. Most of those which
are single fragmentary threads or narrow ribbons have one
edge delicately toothed from end to end ; some are toothed
on one edge toward one end and on the opposite edge toward
the other end. Some have both edges set with fine saw
teeth ; and it becomes evident that many which seem to be
toothed only on one edge have been folded along the mid-
dle so as to bring all or some of the teeth of both edges to
one side. Large collections of these Graptolites have been
made both in Europe and America, and subjected to the
closest examination and comparison. It is quite certain
that these little creatures were a peculiar kind of floating
animal, but nearly as low in the grades of life as plants ;
that they grew from living specks, as the leaves of a tree
grow from buds ; and that they produced at first a foot
stalk, which expanded and multiplied itself and became
gradually furnished with the necessary organs of nutrition
and reproduction. A great number of separate genera and
species of these graptolites existed in that very early age
of the world ; some of which continued to exist for two or
three ages following, and then this whole family of living
creatures disappeared from the waters of the world. In
the age of No. Ill the Appalachian ocean and its extension
through northern Europe was alive with them, incredible
multitudes floating and feeding on the surface and sinking
to the bottom to be fossilized in the slate-mud. It is pro-
bable therefore that the prevailing dark color of our roofing
slates and other beds of No. Ill should be ascribed to the
vast amount of carbon secreted by the graptolites, and at
their death transferred to the slate-mud which was all the
time accumulating at the sea bottom. It is barely possible
(perhaps if we knew more about it we would say it was
quite possible) that colonies and conglomerations of grap-
tolites in some places were dense enough to account satis-
factorily for the thin streaks and nuts of coal mentioned
above. We may imagine that the graptolites floated mainly
at the surface of the water and received the principal part
of their sustenance from the carbonic acid which in those
early ages loaded the atmosphere more heavily than now ;
540 GEOLOGICAL SURVEY OF PENNSYLVANIA.
and that this manner of feeding brings the graptolite life
into close analogy with the plant life of all ages, the leaves
of trees receiving their sustenance in like manner from the
air ; but we must not forget that microscopic life has al-
ways pervaded the world, furnishing the chief food of all
lower orders of creatures.
The relations which existed between these curious ani-
mals, the graptolites, and other animated inhabitants of the
Appalachian sea the solid shells of which are also abund-
ant at some of the outcrops of Formation No. Ill is a sub-
ject of mere speculation. Whether the graptolites had any
intercourse, friendly or hostile, with the multitudes of free-
floating crinoids, or with the submarine meadows of stone
lilies waving their calcareous heads upon long-jointed stalks
rooted in the mud, and spreading their locks of calcareous
hair abroad in search of microscopic food, we cannot tell.
Nor do we know what intercourse there was between these
crinoidal animals and the innumerable shell-fish of various
classes, kinds and species which then lived. A great vari-
ety of species have been figured and described. Most of
them persisted through the whole slate age, then perished to
be seen no more in higher formations; so that a collection of
fossils of No. Ill is quite sufficient to distinguish this forma-
tion from all preceding it and from all that followed it in
geological history; and quite sufficient to identify the out-
crops of No. Ill wherever they may be encountered in
Europe or America.
The amount of coralline life in the Utica and Hudson
River age was very great and a variety of beautiful forms
are figured by Hall in plates 75 to 78 of his first New York
volume, and by Newberry in plates 1 to 4 of the first volume
of the Palaeontology of Ohio.
A considerable variety of shells have also been preserved
in these two formations. Among BR ACHIOPODS were species
of Lingula, Leptaena, Or this, Atrypa, OrMcula, Slropho-
mena, Zygospira. Wiynchonella, Retzia, Nuculites, Cypri-
cardites, Megambonia. Of LAMELLIBKANCHS were species
of Avicula, Ambonycliicb, Modiolopsis, Orlhonola, Lyro-
desma. Of GASTEROPODS there were species of Murcliisonia,
NO. III. UTICA AND HUDSON RIVER. 541
Pleurotomaria, Bellerophon, Cyrtolites. Among CEPIIALO-
PODS were species of Endoceras, Orthoceras, Ormoceras.
Of TRILOBITES there were various species of Dalmaniles,
Acidaspis, Ceraurus, Proetus, Asaphus, Calymene.
Previous to Dr. Walcott's publication in 1890 of his dis-
covery of fisli remains on the Colorado river it has been the
opinion of all geologists that no vertebrate animal yet existed.
Not a trace of any kind of fish has elsewhere been detected
in the first four formations of the Palaeozoic series; the
earliest known fish-spine was found by Professor Claypole
in one of the beds of Formation V, in Perry county (to be
noticed hereafter); nor is there any certain evidence of the
existence of land plants. As the corals of the present day
pervade the trophical belt of the earth, and as a change oi'
temperature of a few degrees is known to produce wide-
spread destruction among the finny tribes of our present
sea, the abundance of coral life and the absence of fish in
the early ages conspire to testify to a high temperature of
the ancient ocean water; and this agrees with our supposi-
tion of the gradual cooling of the globe.
The black Utica slate, and many darker layers of the
Hudson River slate, especially in the western States, have
been so heavily charged with carbon from the decayed
bodies of the creatures which filled the sea, that hand speci-
mens will smoke andtiame in a blacksmith's fire. This has
given them the mineralogical name of fire slate (pyroschists).
Dr. Sterry Hunt in his Tenth Chemical Essay, 1875, page
178, gives analyses of Utica slate composed of 53 to 58 per
cent of carbonate of lime with a little magnesia and ox-
ide of iron; the insoluble part of the rock lost 12.6 per cent
of volatile and combustible matters, leaving a coal black
residue. AVhen this was heated in the open air it lost 8.4
per cent additional, making in all 21 per cent of volatile
and carbonaceous matter in the rock. Very little of this
however was bitumen; the most of it was of the nature of
a true coal. Attempts to distill oil on a large scale from
this rock resulted in the production of only from 3 to 5 per
cent of oily and tarry matter, besides combustible gases
and water.
542 GEOLOGICAL SUKVEY OF PENNSYLVANIA.
It is not likely that the black slates of any part of this
great formation No. Ill will ever be used by the business
world for the distillation of oil, or the production of illumi-
nating gas.
Such pyroschists or black slates have been deposited in
all ages. It will be shown in a proper place that they are
not only sometimes very rich in carbon, but interleaved
with thin beds of coal, deceiving people into the belief that
they can be profitably mined. Such is the case especially
with the black slates near the botton of Formation No. VIII
on the Janiata and elsewhere in the State. It will also be
seen that such pyroschists usually form the roof of every
true coal bed and furnish the material from which the dis-
tillation of coal oil was carried on previous to the discovery
of petroleum. But in the upper or later formations the
carbon distributed through the black shales was certainly
derived in large part from water plants growing in pools
surrounded by a land vegetation. We may, therefore, take
it for granted that the carbon of the black slates of forma-
tion No. Ill was obtained also from the destruction of some-
kind of water plant vegetation, but mixed with the decayed
animal tissues of shell-fish, corals, water-bugs and worms.
It will be shown in describing the Oil Measures, that the
quality of petroleum obtained from formations of different
ages differs greatly, especially in odor; and this is part of
the evidence that the older petroleums are of animal origin
more than vegetable ; and that the newer petroleums (in
Pennsylvania) had a vegetable rather than animal origin.
In speaking of worm tracks as abundant in No. Ill no
mention was made of the forms of the worms themselves ;
for it can be readily understood that such soft creatures,
destitute of internal skeletons and external hard coverings
would die and vanish without leaving any trace except
casts of their barrows, and impressions of their movements.
This is true of the whole family of sea slugs. But there
were in the Hudson River Age, and also in ages subsequent,
vast numbers of leeches, with horny plates in their mouths
set with little tooth-like conical projections. Multitudes
of the shining little cones (Conodonts, see Chapter XLIV,
JSTU. III. UTICA AND HUDSON RIVER. 543
page 507, above) have been found, not only scattered sep-
arately, but in small groups, and in some instances attached
to fragments of the horny plates on which they were set.
What these leeches lived on is an interesting question.
They are found scattered over surfaces of slate on which
appear worm tracks which were probably made by the
animal that owned the teeth. But the size of the animal
and the efficient character of its biting apparatus would
lead us to suppose that there existed then sea animals of a
considerable size clad in succulent flesh ; yet no remains of
that kind have been discovered.
The few limestone beds which are locally interstratified
with the slates, as in Dauphin county, are too thin and
muddy to make them deserving of serious mention in
economical geology ; especially seeing that they crop out
within two or three miles of the north edge of the limestone
belt of the Great Valley. In the outcrops of No. Ill
around the isolated limestone valleys and coves of Middle
Pennsylvania also such interstratified thin limestones have
been occasionally observed. As for example on the slopes
above Spring Mills in Southern Centre county (426, T4).
As there are no iron ore beds in No. Ill, nor any other
metalliferous beds, this formation is of no mineral value
throughout the greater part of the State. Its soil is dis-
posed to be cold and wet ; but otherwise sufficiently fer-
tile ; so that the No. Ill slopes of Bald Eagle, Tussey,
Shade, Black Log, Tuscarora, North and Blue mountains
are farmed by a large number of landholders, the fields ex-
tending half way up the mountain side (T4, 425).
The roofing slate belt.
In one part of the State, however, Formation No. Ill is
of great mineral value, furnishing the finest quality of
roofing, table, and school slates.
The roofing slate belt of No. Ill runs from the Delaware
to the Schuylkill, through the northern townships of
Northampton, Lehigh and Berks, where large settlements
of slate workers have opened extensive quarries, and built
GEOLOGICAL SURVEY OF PENNSYLVANIA.
NO. III.' I PICA AND HUDSON RIVER.
545
nal ^Report, Vol.1, 1831
Slalingtoii section. pL L ,
(D 3 page 13o.)
Small bed* (containing some
Large beds.)
400 Inrlndrx l/ir uuarrij beds around
Hcinbftck.f, and around Slatedale;
exact position unknown.
08 3) 3D. 5ont6 ' roofing slate quarries
100'
(jo 7 WeUhtQOtn rooting slate quarries.
i$LJ J J /
100
uarries
1L / 114 franklin roofing slate quarri
gn ;i
100
,,' Scimesffiess % Cos slate
(Blue vein. Washington cLuarri
210
rcmjinq slate
The
liio* /3l/M> mountain (junrnj.
35
546 GEOLOGICAL SURVEY OF PENNSYLVANIA.
considerable towns connected by railroads. This district
is to Pennsylvania what North Wales is to Great Britain ;
and in the course of time the quarries of Slatington on the
Lehigh and Bangor on the Bushkill will become as worthy
of the pilgrimage of geologists and tourists as the Welsh
slate quarries of Tremadoc. Dr. Chance, in Report of Pro-
gress D3, Vol. I, 1883, describes more than a hundred slate
quarries, old and new, some abandoned, many vigorously
worked, illustrating his descriptions with photographic
views of the older and deeper quarries, and giving many sec-
tions of the beds in which the workings are carried on. The
section along the Lehigh at Slatington (D3, page 147) shows
the folded structure of the formation and the order in
which the principal valuable beds of slate occur. The
measured thickness of the roofing slate part of the forma-
tion amounts to 1529 feet, divided up into small and large
slate beds, separated by groups of beds which are not fit to
quarry (page 135). See plates L and LI.
The groups of beds that are worked may be thus de-
scribed. Group A (at the bottom), 12 feet ; Group B, 25
feet ; Group C, 12 feet ; Group D, 60 feet ; Group E, 50
feet ; Group F, 12 feet. Groups A and B are only 16 feet
apart ; C is 222 feet above B, and separated from D by only
15 feet ; D from E by 12 feet ; E from F by 73 feet. But
these only represent beds that have been successfully
worked on the Lehigh river. Many others have been
opened and tested but not worked.
In a general way it may be said that the upper beds of
slate run parallel with the foot of the Blue mountain, at a
distance of from half a mile to a mile from it. The out-
crop of the lowest beds runs rudely parallel with the other
at a distance of from half a mile to a mile further south.
These variable distances from the Blue mountain and from
each other are in consequence of the folded condition of the
formation, bringing up the same beds to the surface in
small and large waves again and again. The slate quarries
furnish fine opportunities for studying the character and
quantity of the earth movement which has thrust the whole
country northward. In no other part of the slate belt No.
NO. Til. UTICA AND HUDSON RIVER. 547
III from the Delaware to the Potomac can the exact quan-
tities of its folding be obtained ; but the openings in Lehigh
and Northampton are so large and numerous, and so close
together, that transverse sections can be constructed with-
out much difficulty, and the shape of the plications can be
represented to the eye (as in plate L).
It must not be supposed that the slates sent to market
are the original laminae of the beds deposited one above
the other and split asunder. The beds of the formation
will not thus split. Although originally deposited in leaves
or thin sheets of mud these original layers have been com-
pacted into a solid mass and cannot now be separated by
human tools. Even if they could be so separated they
would be useless to man, because they are bent into curves.
Fortunately for our arts of life the pressure which folded
the beds produced another and very remarkable effect upon
them. Being a great and uniform pressure from the south
toward the north, it subdivided the whole formation into
millions of thin plates, perpendicular to the direction of
the pressure ; and these are the plates which are split
asunder by the quarrymen and sold for various purposes.
Thus we have curved planes of original stratification, and
straight smooth planes of pressure-foliation. The most
striking feature of the slate quarry to the eye of a spectator
is this double-banded structure of the rocks. He sees the
face of the quarry crossed by the foliation in straight
lines, seldom vertical, but usually dipping steeply toward
the south ; and the quarry operations follow these bands
and pay no attention whatever to the original stratified
beds of the formation. Across the bands of foliation
the curved ribbons of the folded strata are seen passing
from one side of the quarry to the other in a series of
waves, each stratum distinguished from the strata above
and below it by either strong or delicate differences of color.
Every one must have noticed in rooting slates, and some-
times in writing slates, bands of a lighter or darker tint
crossing them ; these reveal the original sedimentation.
Every one must have noticed on dark writing slates, whitish
spots, and that the slate pencil when it leaves the black
548 GEOLOGICAL SURVEY OF PENNSYLVANIA.
,'sm
i Xuadn Quarry. M.S Z. KJlaiinuS Quarry, X, .
3. SSayaf Quarry, X. Si. 4. Tallin ftm Quary, 76 fc
NO. III. UTICA AND HUDSON RIVEIl. 549
, Matec/uam^ on
550 GEOLOGICAL SURVEY OF PENNSYLVANIA.
surface and crosses such a white spot will not bite. These
white spots are small pellets of clay in the original sedi-
ment mashed flat and enlarged, and reduced to an exceed-
ing thinness by pressure. See plates XXXVIII, XXXIX.
Another interesting phenomenon connected with the
planes of foliation is their frequent fan-shaped structure,
especially where the original beds are sharply bent upon
themselves ; for, since the foliation was produced by pres-
sure, and in planes perpendicular to that pressure, when-
ever the mass was sharply bent the direction of the pres-
sure was modified on the two sides of the fold, causing the
planes of foliation to diverge. This will be sufficiently ex-
plained in a more detailed description of the slate region.
As the development of the cleavage planes or slate foli-
ation was produced by the pressure expended by an earth-
movement from the south, and as the amount of this move-
ment must have been measured by the number and sharp-
ness of the anticlinal and synclinal rock-folds which re-
sulted from it, we should expect the greatest amount of
foliation, that is, the greatest number of workable slate beds
to be in districts where folds are most numerous. At the
first glance this would seem to explain the fact that there
are only two workable slate beds on the Delaware river, for
there the whole mass of Formation No. Ill slopes north-
ward in a very regular way, with dips of 20 increasing to
35 at the top (in the Delaware Water Gap) where the upper-
most Hudson River beds are seen going down beneath For-
mation No. IV.
On the Delaware river there is an almost total absence of
the sharp small rolls and basins which are so prominent a
feature on the Lehigh river; and this has given an oppor
tunity for a fair measurement of the thickness of the forma-
tion north of the great anticlinal which crosses the river
about 2 miles south of the Gap. Its upper series of beds'
measured from the base of No. IV down to Williams' old
slate quarry count up say 1540 feet; the lower series meas-
ured from Shocks down to Belvidere counts up say 3700
feet; the total of 5240 feet ought probably to be increased
to 6000.
NO. III. UTICA AND HUDSON RIVER. 551
The upper series consists of beds which are commonly
more than one foot thick; and the lower series, of beds
which are usually less than one foot thick (Sanders' report
in D3, page 85). An independent set of measurements
along the Delaware river gives an equally large estimate,
and places the two slate quarry beds at 1000 feet and 2350
feet respectively beneath the base of No. IV (Chance's re-
port).* These five or six thousand feet of rocks consist of
beds of slate varying in thickness from only one hundredth
of an inch up to a maximum of at least 30 feet; being nearly
all of them of a dark grey bluish black color; some of them
of very fine-grain ; others coarser ; and some coarse enough
to be considered sandstone, but not continuous.
It has already been said that No. Ill in its frequent ap-
pearances in Middle Pennsylvania west of the Susquehanna
river exhibits nothing like this thickness. At Orbisonia in
southern Huntingdon it measures only 1870 feet (Ashburner
F, 160). At Logan's gap in Mifflin county it measures 2304
feet.f In Blair county gaps the whole formation was esti-
mated at only 900 feet. In Penns valley, Centre county, it
is estimated at 800 feet or upwards (T4, p. 425) without any
distinction being made between Hudson and Utica. In
Friends cove and along the Jnniata in Bedford county it
seems to be about 700 feet.:}:
Seeing that the roofing slate beds are confined to the east-
ern end of the Great Valley in Pennsylvania, it looks as if
they constituted a separate formation and were not deposited
to the westward; the thinning of No. Ill toward middle
Pennsylvania being possibly explained by that fact. The
belt of roofing slate, however, runs on through northern
New Jersey and southern New York toward Newburgh on
the Hudson; and important quarries have been opened in
later years along this line.
* In Munroe township, Lebanon county, Mr. Sanders got by construction
6000 feet for the probable total thickness of No. III. But in the geological
reports rf the New Jersey Survey an estimated thickness of only 3000 feet is
assigned to the whole Formation No. Ill along the Delaware river.
f Hudson River 937, Utica, Upper Gray 210, Utica, Middle Black 302,
Utica Lower Gray 855 feet (F, p. 55).
t Utica being 200 feet.
552 GEOLOGICAL SURVEY OF PENNSYLVANIA.
The continuation of the belt beyond the Hudson along
the New York-Massachusetts line through Vermont into
Canada, has given rise to the most protracted, the most
vehement, and undoubtedly the most important discussion
which has ever agitated the American geological world. It
is called the discussion of the TAOONIC SYSTEM.*
*It commenced upon the publication in 1844 of the report of the New York
geologist, Dr. Emmons, upon the rocks of northern and eastern New York '
and it has been participated in by almost every geological field worker in
the United States, and by several of the most distinguished geologists ot
Europe. It has not ceased yet ; and in fact the controversial literature on
the subject has been largely increased in the last few years. The hinge of
the controversy is the question whether the great slate formation of the
Taconic mountains in New York and of the plain between the Green mount-
ains of Vermont and Lake Champlain is really Formation No. Ill of Penn-
sylvania and the Southern States ; or whether it represents the older and
underlying Cambrian system of formations.
The place where the most perfect cross-section has been made is in Georgia
county, Vermont, where broad outcrops of four formations, two of slate and
two of limestone, alternate, and run side by side. Some look upon these
two slate belts as repetitions of each other and the two limestone belts as
repetitions of each other. If there be no repetition, we have at the bottom
1000 feet of fossiliferous limestones ; then 3750 feet of slate (the lowest 200
feet, Georgia shales crowded with fossils and the uppermost 50 feet a quart-
zite); then 1700 feet of limestone (many of the beds broken into breccia);
then from 3500 to 4500 feet of slate. (Bulletin U. S. G. Survey No. 30, C. D.
Walcott, 1886). If there be a repetition we have a state of things greatly
resembling the geology of Lehigh and Northampton counties in Pennsyl-
vania, namely, a limestone formation measuring 1000 or 2000 feet in thick-
ness like No. II, overlaid by a slate formation between 3000 and 5000 feet
thick, No. III. Resemblance is rendered the more striking by the presence
of beds of roofing slate quarried along the outcrop. Those who claim no
repetition, that is, who refuse to believe in the existence of a fault bringing
up again the lower limestone and slate to the surface to make the upper
limestone and slate, have constructed the extraordinary theory, that the
upper limestone is a lenticular or local deposit in the body of the slate for-
mation. A lenticular limestone formation at least 1700 feet thick seems to
me a physical impossibility ; and it is evident to those who have studied the
Appalachian faults that a great fault must run through Georgia county, Vt.'
which swallows up the upper limestone at its north end, and a large part of
the upper slate in the same direction. The discussion is, however, at pres-
ent in the hands of palaeontologists, who are not deterred by structural laws
when these present extraordinary obstacles to their classification of the
rocks by the fossil forms which they contain.
It is evident that, if the Cambrian age of the Vermont limestone and
slate be forced upon us as it seems to be ; and especially if the two great
limestone and two great slate formations of Georgia, Vermont, be insisted
upon, then it becomes impossible to explain their absence in New Jersey
and Pennsylvania. It throws doubt upon the identification of the Potsdam
NO. II r. UTICA AND HUDSON RIVER. 553
As the slates of >No. Ill are seen going down beneath the
northern edge of the Mesozoic formations along the Leba-
sandstone along the foot of the South mountain under the Lehigh valley
limestones ; and it breaks all connection between the well-established
geology of the Great Valley from Alabama to New York with its evident
continuation through Massachusetts and Vermont into Canada. If the
roofing slates of Georgia county Vt. underlie the Potsdam then they can-
not be in the same formation with the roofing slates of No. Ill ; and it be-
comes necessary to repeat again and again the great fact that at the bottom
of our roofing slates of No. Ill lie the black Utica beds, and underneath
these lie the uppermost beds of No. II containing Trenton fossils.
Tt would be a most astonishing thing if 10,000 feet of slates and limestones
in Vermont and eastern New York should be wholly wanting in New
Jersey and Pennsylvania ; and at the same time at least 8000 feet of slates
and limestones on the Delaware river should be entirely absent east of the
Hudson.
It may be objected, that the 6000 feet of No. Ill on the Lehigh and Dela-
Avare fades away to 700 or 800 feet on the West Branch Susquehanna and
upper Juniata rivers. But we must remember that the direction of this
thinning is across the measures northwestward; and that the gi eat thick-
ness of No. Ill reasonably maintains itself along the line of strike from
northeast to southwest. Therefore it is to be expected that No. Ill will be
as thick in Massachusetts and Vermont as it is in the Great valley of New
Jersey and Pennsylvania. It is a conclusion of equal validity that if- No.
Ill diminishes in thickness from its Great Valley outcrop northwestward
toward the Allegheny mountain it must have been of equal or greater
thickness in its original area southeastward toward the Atlantic Ocean ; and
although the destruction of this great formation over all that part of its
original area has been almost if not quite complete, yet we ought to find
fragments of it in southeastern Pennsylvania which have escaped such des-
truction. We may not be able to recognize 'it with absolute certainty in
such preserved patches, because of the universal metamorphosis which all
the rocks of southern Pennsylvania have evidently undergone. In other
words, if the limestones of No. II preserved in Lancaster county, in tue
Chester county valley, and in similar basins still further and as far south as
the Delaware State line, gradually change iheir aspect and become beds of
white crystalline marble, we ought to expect that the slates of No. Ill if
preserved anywhere south of the Great Valley should also present a similar
difference of aspect, and show themselves as crystalline slates or schists,
perhaps even as chlorite slates, talc slates or mica slates. But it is well
known that limestones are always much more changed than mud rocks are;
except when the mud contains an unusual percentage of magnesia andiron.
Unfortunately too little attention has yet been paid to the chemical analysis
of the beds of No. Ill ; and therefore we are not in condition to speculate
safely upon the degrees and varieties of crystallization which the slate beds
of No. Ill might assume in the highly metamorphic region of southeastern
Pennsylvania. Without this chemical knowledge we cannot argue to
conclusion the moot question whether the South Valley Hill slate belt in
Chester and Lancaster counties is a preserved part of No. Ill, or whether it
is an older (Cambrian) formation brought to the surface by a great fault
running along the southern edge of the Chester county valley.
554 GEOLOGICAL SURVEY OF PENNSYLVANIA.
, Onddci
LIIJ
water gap; coat dida.
yap.
NO. III. UTICA AND HUDSON EIVER. 555
nori county southern line, and at the south foot of the
South mountains between the Schuylkill and the Dela-
ware ; and as slates, apparently No. Ill, are brought up to
the surface through the Mesozoic by the Doylestown fault,
we have a right to suppose that the slates of No. Ill form,
at least in some places, the floor of the Mesozoic belt along
parts of its range ; although there are good reasons for
believing that the principal part of that floor consists of the
eroded outcrops of the limestones of No. II, which are seen
rising from beneath it, without any slate, at Norristown.
It is not surprising, therefore, that Dr. Frazer, in his sur-
vey of Lancaster county, observed at several places, a slate
formation, very black and lustrous, which may be inferred
to be Titled slate^ because overlying the limestone forma-
tion No. II. This is rendered the more probable when, as
at Brickerville, in Elizabeth twp, the black slates appear
emerging from beneath the south edge of the Mesozoic, as
if they were connected underground with the No. Ill slates
of Lebanon county. They are so black that excavations
have been made in them in the hope of finding coal ; but
their principal interest to the geologist arises from their re-
semblance to the Peach Bottom roofing slates which have
already been mentioned as crossing the Susquehanna river
at the Maryland line.
The Peach Bottom roofing slate belt projects northeast-
ward into Lancaster county and southwestward through the
corner of York county into the State of Maryland. It ap-
pears to be a closely folded basin about 9 miles long, the
beds dipping nearly vertical. Eight principal quarries have
been worked, some of them for many years, to a maximum
depth of 200 feet. As in the Slatington region, so here, the
quarries are not continuous, the roofing slate quality varying
lengthwise of the basin.
It is described in more detail in Chapter XIII, page 141
above, but it requires mention here because it has been sup-
])osed to be a far south outlier of III, and its quarries have
been compared with those on the Lehigh, on the strength
of numerous undescribed seaweed-like fossil markings on
the faces of some of the slates, which our great master in
55(5 GEOLOGICAL SURVEY OF PENNSYLVANIA.
Palaeontology, James Hall, pronounced to be possibly a
species of ButhotrepMs, a genus of Hudson River age.*
This is a slender support for so important a theory. The
fact of a roofing slate foliation of some of the beds goes for
nothing; or rather is in favor of a Cambrian age, when the
great slate quarries of Wales, and Vermont, and the
quarries now being opened in the South Mountains of York
and Adams counties are considered. It is hard to imagine
the Peach Bottom slates to be III, and the great limestone
formation II to be wholly absent from the district; and in its
place the Chiques quartzite (see page 183 above); while the
surrounding region consists of mica and chlorite schists.
It hardly seems worth while to conjecture that the Peach
Bottom slates represent the upper member of No. Ill, and
the mica schist country the lower division metamorphosed
regionally. It is still less worthy a conjecture that the
Lehigh slate belt is a separate formation deposited where
the rest of III and the whole of II were not deposited. In
Pennsylvania such non-conformability of deposition is
scarcely possible, however probable it may be elsewhere, in
Canada for instance, f
*Prof. JohnS. Stohr, of Franklin and Marshall College, Lancaster, Pa.,
read a paper before the Linmean Society, in 1886, to draw public attention to
the Peach Bottom fossils. Subsequently, in a letter to me dated May 20,
1886, he says that one of the specimens in his possession "seems to have a
woody stalk, with pinnae extending from both sides, but not distinct enough
to determine their character. What seems to be pinn<e are probably lobes
or branches of some fucoid like Buthotrephis ; and what seems to be the
stalk or axis is partly mineral incrustation. When I first showed a speci-
men to Prof. Porter, of Lafayette College, he exclaimed, "Oh, that is dendri-
tic ;" but when I showed him another lie said, " No, that is evidently the im-
pression of a plant, and it looks very much like a fern." " So far as ferns are
concerned I have never yet been able to convince myself that any of the
impressions I have seen are really those of ferns, although some of them
strongly resemble ferns."
f Mr. Alex. Murray reported in 1879 that in all places where fossils could
be obtained the Hudson river formation (No. Ill) overlaid unconformably
the serpentine beds which overlie the Levis beds of the Quebec group, and
that the nonconformity becomes so great in part ot the islands, that the
whole Hudson river formation and all the Silurian formations are wanting,
and Devonian rocks lie upon the serpentine beds, which he suggests may
represent the (Jhazy beds of No. II. Intrusive masses mark the break
(Geol. Mag. Notice, March, 1879, p. 139).
THE THICKNESS OF NO. III. 557
CHAPTER XLVI.
The thickness of No. 111.
The original thickness of the combined Hudson River
and Utica slate formations in the region of the Great Val-
ley cannot now be measured by reason of the excessive
crumpling to which the whole deposit has been subjected,
by a side pressure from the direction of the South mount-
tains.
It is easy to see that oceanic deposits of gravel, sand and
mud, when pressed sideways (by the shrinking of the size
of the globe, or any other cause), and lifted thousands of
feet into the air, along certain lines, while in their wet state,
charged with ocean water, and therefore as plastic as putty
or wax it is easy to see that they would have their solid
shapes changed in various ways.
The thick deposits of gravel and coarse sand would be
folded, but not crimped ; and their original thickness would
be somewhat swollen everywhere ; in some parts much
more than in others ; and it is even possible that where
they were originally thickest they would be artificially
swollen most.
The thinner layers of liner sand would be also folded, but
the folds would be smaller and more numerous. And as
the finer sand deposits are always in company with mud
deposits, their smaller foldings would be made to some
extent at the expense of the mud layers ; and this would
save the sand layers from being thickened.
The deposits of fine mud, whether the common feldspar-
quartz mud of No. Ill, or the lime-mud of No. II would
be crushed out of all recognizable original shape ; would be
swollen in whole and in parts, and distorted by myriads of
folds, crimps or creases in every direction.
558 GEOLOGICAL SURVEY OF PENNSYLVANIA.
We have any number of illustrations of the above men-
tioned three modes in which the various great deposits have
actually had their bulk enlarged and their shapes distorted
in all parts of Middle Pennsylvania, but especiall} 7 in south-
eastern Pennsylvania. It is only necessary to follow the
banks of the river channels cut across the outcropping for-
mations to see how the great sandrock and conglomerate
formations No. IV, No. X and No. XII are grandly curved
how the smaller and finer sands and shales of Nos. V,
VII, VIII, IX and XII are thrown into series of smaller
folds how the great soft mud formation of No. XI is
closely complicated and how the slates and limestones of
the Great Valley (Nos. Ill and II) are crumpled and mashed
together in thousands of pleats, which crowd each other
out of line, so that in many of the outcrops the strata seem
to run more across the vaUey than lengthwise of it.*
Illustrations of this condition of things in the limestone
belt have been already given in this report ; but here it is
only needful to state the fact, which has no doubt arrested
the attention of most of the inhabitants of the Valley with-
out their assigning any geological importance to it. Geolo-
gists however have observed it with special interest be-
cause it is calculated to raise a doubt concerning the age
of the formation, and its true relationship to the overlying
formations, because it creates the impression that the lime-
stone formation was crumpled and uplifted from the ocean
and worn away to a level surface, and submerged again, to
be covered by the slate formation. In other words, geolo-
gists have found it hard to harmonize the irregular detailed
stratification of the limestone with the conformity of the
whole underlying limestone formation to the whole over-
lying slate formation.
And the same apparent difficulty is reported in the case
of the irregular local dips and strikes of the slate belts,
especially along the northern or upper edge of the belt,
*See the illustrations of folded beds in the slate quarries in Report D3.
See especially Fig. II, page 119, D3, whtsre a bed of slate is thickened in the
fold. See also the numerous sections of thickened folds in the Anthracite
Reports A A.
THE THICKNESS OF NO. III. 559
where the top slate strata are overlaid by the very regular
sandstone formation of the North mountain. This has
bred a suspicion that the two formations (III and IV) are
UJiconfoj mcible did not follow each other immediately in
time but that the slate formation was elevated and eroded
and resubmerged to receive the long subsequent sand de-
posits.
But let it be once understood that if a very thick fine
shaly, slaty or muddy formation lies. between two very
massive, coarse, sandy or gravelly formations, and all three
are subjected to a great side pressure, the sands will be
merely thrown into great waves, but the mud will be badly
crumpled together in thousands of closely compressed small
local folds the idea of non-con for inability at the contact
of the limestone and slate belts of the Valley, and at the
contact of the slate belt and the North mountain sandstone,
will no longer impose upon the imagination.*
The thickness of Formation No. III.
To return then to the starting point of this chapter, it is
quite impossible to measure the thickness of the slate for-
mation No. Ill along the Great Valley on account of irs
closely folded, swollen and distorted condition. All that
we can say is, that in Middle Pennsylvania, where it is not
in that condition, where it is merely upturned, it has been
measured pretty accurately ; and while it is in some places
only 1000, in other places it is 1600 feet ; being thinner
towards the Allegheny mountain and thicker towards the
South Mountan.* How much of this difference is due to the
original thinning of the deposit northward, and how much
of it is to be set down to the diminished intensity of the side
pressure as we recede from the South mountain range, can-
not be known.
That it increases in thickness eastward is indicated by
the fact that the measurable thickness increased from 700'?
*For further remarks upon this subject see foregoing chapters on the lime-
stone belt, and a following chapter on the non-conformity of IV upon III.
560 GEOLOGICAL SURVEY OF PENNSYLVANIA.
at Bedford* (Stevenson), and 900' ? at Tyrone city (Platt and
Sanders), to 1000' at Belief onte (H. D. Rogers), f and 1600'
at Logan Gap (H. D. Rogers).:}:
As Prof. Stevenson says that it is decidedly thicker at
McConnellsburg than at Bedford, and as Messrs. Aslibnrner
and Billingot a measurement of 1870' at Orbisonia, we must
suppose it to increase also in a southerly direction. Taken
together these data lead us to expect a great thickness in the
Chambersburg valley ; and an increasing thickness from
Chambersburg towards Harrisburg, Reading and Easton.
It is not so astonishing then as it otherwise would be that
both Mr. Sanders and Dr. Chance gives it a thickness of
6000' at the Schuylkill, Lehigh and Delaware water gaps.
* In Bedford county Prof. Stevenson estimates the total thickness of both
Ilia and III6 at 700' ; for an outcrop 1040' wide with dips ot 30 to 60 follows
Tussey mountain across the Juniata below Bedford ; and the same estimate
is made along Evitt's mountain on the west side of Friend's cave. But in
Fulton county, around the edge of the McConnellsburg cove, he says, the
thickness is evidently greater. The Utica (Ilia) on the Bedford pike near
Williams Grove is about 200'. (T2, p. 93).
t Mr. D'Invilliers calls it at Bellefonte 1011', in Report T4, p. 304.
\ Billin and Ashburner's measurement make it here 1632'.
Prof. Cook says that in New Jersey it cannot be accurately measured,
bxit calculates from steep N. W. dips across a 2 mile belt from the Delaware
water gap south to Columbia it is probably 3000'. But 2 miles at only 15
would make 3000', and the dips are much steeper than that; see sections in
Reports G6, and D3.
The latest precise thickness of the formation was got (in 1886) by my
lamented assistant, Mr. C. E. Ashburner, from a study of the Knowersville
gas well in Albany county, N. Y., 25 miles west of Albany. It struck the
top of the Trenton limestone (II) at 2880', and went 112 into that formation ;
mouth of well about 500' above tide; top of Hudson river slate (III) 550'
above well mouth ; therefore total thickness of 111,3430'. The lower part
of the formation is calcareous. Specimens from 2500' downward were
analysed and yielded 25 per cent of carbonates, lower down 10 per cent ;
at the top of the Trenton the percentage suddenly rose to 60 per cent and
soon to 80 per cent; continuing at that to the bottom of the boring. The
dark Utica formation (Ilia) was plainly distinguishable, lying on the
Trenton, and calcareous, as stated above. The bottom of the Lower Helder-
berg limestone (VI) rests directly upon the top of the Hudson river states
(III6) Clinton and Medina (V, IV) being entirely absent in this part of
New York. The Cauda-Galli (VII&) makes a bold cap tQ the mountain,
and is probably the cause of the cliff which runs along the escarpment for
many miles westward towards Utica.
The Clyde well in Wayne county, central New York, is said by Prof. C. S.
Prosser of Cornell University to have gone through Oswego sandstone, 210' ;
shale and sandstone, 170' ; Hudson river and Utica 650' ; total 1030', to top
of Trenton limestone. (American Geologist, Oct. 1890, page 204.)
THE THICKNESS OF NO. III. 561
Whether the formation be 3000' or 6000' thick along the
Susquehanna above Harrisburg cannot be discovered; but
that it is several thousand feet thick is certain, from the
fact that, although the belt is about 4 miles wide, occupy-
ing the river banks all the way from the upper part of the
city to the Penn. RR. bridge in the gap, yet the under-
lying limestone formation is never once brought to the sur-
face by any of the folds.
And this is the case eastward through Dauphin county,
and westward through Cumberland county. Not until we
go six miles into Franklin county, to within 2 miles of
Strasburg, does the underlying limestone begin to appear
on the sharp top of the Strasburg anticlinal, which keeps it
at the surface from here on into Maryland.
The point near Strasburg where the limestone appears is
about a mile from the crest of the North Mountain. Two
separate exposures of slate a mile southwest of Strasburg
show each a dip of 60; and this maybe taken as the dip of
the whole formation from Strasburg to the mountain; which
would give it a total thickness of something over 4000'.
Proceeding further west to the Bedford pike at Mercers-
burg, the slate belt is there only about a third of a mile
wide, which, on a dip of 70 (in the limestone), would re-
duce the thickness to 1500'; but there is some reason to
think that part of the slate formation is here overlapped by
a fault at the contact of the limestone.
36
562 GEOLOGICAL SURVEY OF PENNSYLVANIA.
CHAPTER XLVII.
Character of Formation No. III.
The slate formation consists of dark mud-rocks (slate)
more or less sandy; many interpolated layers of fine sand-
stone; a few layers of poor limestone, or limy mudstone,
not to be compared in quality with the limestone beds of
the southern side of the valley; and here and there, at dis-
tant points in the length of the valley, beds of sandstone so
coarse as to deserve the name of conglomerate.
The slates are softer and darker in the lower part of the
formation; and are sometimes quite black at the very bot-
tom of the formation, just over the limestone No. II.*
They are harder and more sandy (and the beds thicker
and more massive) towards the upper part of the formation;
and here we find most of the sandstones, some of which can
furnish good flag-stones, and are in fact quarried in Berks
county.
These sandstone beds are mostly grey, sometimes olive,
sometimes greenish in hue. The intervening slates are
mostly dark grey, sometimes olive or greenish and some-
times a pronounced red. These colors are given to the
rocks by small percentages of carbonate and oxide of iron
distributed through the mass ; but nowhere concentrated
into iron ore beds.
It is remarkable that the red color is not noticeable along
the Great Valley in New York, New Jersey, f and eastern
Pennsylvania until one approaches the Schuylkill river.
As soon as Berks county is entered outcrops of red slate
* This is the Utica slate formation of the New York geologists. The main
bulk of No. Ill is understood to be the Hudson River formation.
t Prof. Cook speaks in one place of slates exposed in a railway cut being
reddish-yellow, fragile and earthy, contrasting strongly with the dark blue-
black solid roofing-slate variety. Geol. N. J., 1868, p. 138.
CHARACTER OF FORMATION NO. III. 563
become numerous ; increase in number through Lebanon
county; and can be seen traversing Dauphin, Cumberland
and Franklin into Maryland. In Virginia and Tennessee
the whole formation gradually takes on a reddish color, and
is quite red in many places.*
The place of the red slate belt in the formation is a matter
of some moment and will be discussed after and in connec
tion with a description of the roofing slate belt further on.
It is possible that the red color is one of the consequences
of the decomposition of iron pyrites finely disseminated
through the original mud, because iron pyrites itself is one
of the commonest ingredients of the slate formation as a
whole, and is abundant enough at some of the slate quar-
ries to oblige their owners to reject the beds which are most
infested with it. Several instances are mentioned by Mr.
Sanders in report D3. Prof. Cook speaks of several local-
ities where pyrites is disseminated through the rock mass.
But it is much more likely that the red slate beds were
originally deposited as red clay, and that the presence of
pyrites is merely a coincidence ; for pyrites is perhaps more
abundant in the roofing-slate part of the valley east of
where the red rocks begin to make a show ; and moreover,
the sulphur of the pyrites unites with the alumina of the
slate rock to produce the white efflorescence which is so
often to be seen, while the iron set free is carried off by the
waters. At all events there is no apparent precipitation of
limonite.f
The amount of iron in the rooks of the slate belt must
* This is very surprising to a geologist fresh from Pennsylvania, accustomed
as he is to see the red formation always lying back of the mountain and not
in front of it ; and the change in III from gray to red going south is still
further accentuated by a corresponding change in V from red to gray.
|To show that the amount of iron in slates and shales is not necessarily
influential in reddening them it is only needful to compare the following
analysis by Mr. McCreath :
1. Yellowish white damourite slate of Lehigh county, from the bottom of
No. II, two specimens. (Report M,page 92.)
2. Red shale from the Catskill No. IX of Tioga county. (Report MM,
page 372.)
3. Catskill red shale from Wayne county. ( M3, page 108. )
564
GEOLOGICAL SURVEY OF PENNSYLVANIA.
vary within a small and narrow range. Prof. Cook gives
the following analysis :
A. Ordinary bluish black Delaware Gap roofing slate.
B. Sandy massive Deckertown-pike slate.
Silica,
Alumina
Protoxide of iron, .
Lime,
Magnesia, ...
Potash,
Soda
Carbonic acid, . .
Carbon [graphite?],
Sulphur,
Water,
A.
56.60
21.00
5.65
3.42
2.30
1.10
0.50
2.20
2.69
0.57
'3.00
77.60
7.32
B.
68.00> 82 4Q
14.40>
5.40
2.68]
!:Sh
O.llj
2.30
2.70
99.10
The pyrites (sulphide of iron) so universally disseminated
through the slate formation must have been one of the
original constituents of the oceanic mud ; for there are no
traces anywhere to be found of either ancient or modern
volcanic action in the Great Valley, to supply sulphur.*
The amount of sulphur also, in any specimen of slate is so
small that we must suppose it derived from the sea water
Silica, ....
55.880
1.
60.530
2. 3.
59.630 59.260
Alumina,
Oxide of iron,
Lime,
Magnesia,
Water,
Alkalies,
19.400
10.570
.080
1.710
8.170
3.760
17.400
9.290
.080
1.920
5.510
5.270
18.560 19.877
.8.571(a) 10.071(6)
.672 .250
2.252 1.917
4.560 3.600
5.109 4.855
Sesquiox. manganese, .
Sulphuric acid, ....
Phosphoric acid, ....
.290
.123 .012
.279 .058
99.570 100.000 100.046
(a) and (6) are sesquioxide of iron.
Dr. Genth's analysis of the blackish Peach Bottom roofing slate, the red
dish white and the greyish white damourite slates of Lehigh county (Re-
port B, page 126) show that the green specimens had more iron than the
reddish.
* The two trap dykes which cross the valley, one in Cumberland county
and one in Berks county, are of so local a character that they need not be
considered.
CHARACTER OF FORMATION NO. III. 565
above, rather than from the earth-crust beneath the oceanic
mud. But if it came from the sea waters it must be as-
cribed to sea vegetation ; about which however we know
very little, because the marks which that vegetation has
left on the slate rocks are few and indistinct, especially so
along the slate belt of the Great Valley. In New York
state however great numbers of what seem to be sea-weed
forms are found in the Hudson river slate formation No.
III. At all events, we know that the ocean waters in that
age swarmed with innumerable living things called grap-
tolites ; and if these were more animal than vegetable, still
it is not to be supposed that the waters were not quite as
prolific of other kinds of more strictly vegetable life, and
in sufficient quantity to furnish all the sulphur required to
explain the analyses. Much of this vegetation was prob-
ably of microscopic size and infinite fecundity. We can-
not otherwise account for the sustenance of the innumer-
able swarms of animals which then populated the sea; es-
pecially the free-swimming trilobites^ 6f all sizes from an
inch to a foot in length. But besides trilobites there was
the greatest abundance of other kinds of animals chain
corals, star fish, shell fish of many kinds as well as flesh-
eating cuttle fish * in other regions of the ocean, if not in
the part of it which is now Pennsylvania. And a few frag-
ments of land plants have been found, which compels us to
believe that rivers brought plenty of decayed vegetation into
ths sea, and therefore a percentage of sulphur. And of
course the same rivers must have brought down to the sea
the mud out of which our great slate formation was made.
The continent must have been large from which so much
mud was manufactured ; and the rivers must have been
huge which brought so much stuff to the sea. Its fineness
shows that the mouths of these rivers were at a great dis-
tance ; and probably there were vast deltas, mud-flats. If
so, it is impossible not to imagine them covered with some
sort of salt water vegetation, and that will help to account
for the abundance of such shell fish as liked the shallows.
* A rather dangerous term for popularizing the designation Cephalopod ;
but one can do no better.
566 GEOLOGICAL SURVEY OF PENNSYLVANIA.
That the deltas and shallows must have been at a great dis-
tance from the present site of our Great Valley is evident ;
for it is impossible to suppose 5000 or 6000 feet of mud to
have been deposited in any but a deep sea basin ; for if the
shores had been near, some of the earlier and middle beds
would have been of coarse sand and gravel ; but none such
were deposited until the basin had become well filled and
the shores approached nearer by some change of the world's
ocean level ; then indeed, the upper flagstones of No. Ill
were deposited over the older fine muds ; and finally the
off-shore shingle of No. IV (Oneida conglomerate and
Medina sandstone) was spread overall.
These considerations are offered here not for the purpose
of settling scientific questions still under discussion among
geologists ; but to familiarize the minds of readers of this
report with the extent and complexity of our geological
phenomena ; and to illustrate the value of the practical rule
to keep all the facts in view for explaining each one.
Quartz veins are very numerous in many parts of the
slate belt. They are seldom more than an inch or so thick
and usually cut across the beds, but often insert themselves
between the slates.
The substance matter of these veins, which is now so
glassy and brittle, was originally fluid, and deposited itself
in any open crack or fissure in the rocks, however small.
This fact was practically discovered by Dr. Graham of Lon-
don about 20 years ago, when he succeeded in separating
silica in a jelly-like state from other elements with which
it is commonly combined as a hard rock. Graham's gel-
atinous silica (or fluid quartz) can now be made by any
chemist and kept in bottles for a long time before it will
harden into quartz. Nature has been manufacturing it in
all ages and in immense quantities, and has put it to sev-
eral particular uses, one of which is to make gems like the
precious opal, etc.;* but chiefly to heal the wounds of the
*A beautiful example of the use which Nature makes of gelatinous silica
is the production of a kind of opal above a bamboo joint These lens-shaped
stones, called tabasheer, are sold for "madstones" or "snakestones" in
India. See G. F. Kunz's paper on " Madstones and their Magic " in Science,
Vol. XVIII, No. 459, Nov. 20, 1891, page 286.
CHARACTER OF FORMATION" NO. III. 567
rock formations after earthquakes, to fill up all the cracks
opened in the strata (when compressed and folded and
foliated like those of the slate belt) with vein quartz.
The material out of which nature manufactured the fluid
quartz is indicated by the analyses on page 564 above.
The specimen of Delaware gap roofing slate (A), when
analyzed, was found to be more than one-half silica. The
other specimen (B) was about two-thirds silica. In fact,
taking the whole slate belt of the great valley together, if
we could analyze it as a single specimen, we should proba-
bly get from it about 60 PER CENT of silica, 20 PER CENT
of alumina and the remaining 10 PER CENT would be lime,
magnesia, soda, potash, iron, carbon, sulphur, oxygen, hy-
drogen, with traces of other rarer elements.
Thus we see that the original mud deposit was mainly
silicate of alumina derived from the wear and tear of feld-
spar rocks on some distant continent. But a certain extra
amount of silica came from the wear and tear of silicate
rocks not feldspar ; and this extra amount was an availa-
ble reserve for the natural manufacture of vein quartz after
a long lapse of time.* For the veins had to be opened be-
fore they could be filled. The original mud had no fissures
in it. When the bed of the sea was lifted into the air,
dried, hardened, folded and fissured, the deposit of vein
quartz took place. The whole mass was still warm as well
as wet, not merely warm but hot,+ and must have remained
so for an indefinite number of ages since the cooling could
take place only at the surface of the whole mass, now
elevated 30,000 feet above its former level. The sea water
still resident throughout the mass shared the high temper-
ature of the mud deposits, dissolved a portion of their
silica, and filled the cracks with vein quartz.
* Of course the above statement is too short and simple to be in any sense
complete. Chemists and geologists will fill it out for themselves. But
some true and easily-seized notion of the genesis of quartz veins ought to
be given to the uninitiated.
f The law of increase of heat downwards from the surface, at the rate of 1
F. per 60' depth (added to the local invariable annual mean temperature
ten feet beneath the surface) would give the rocks of No. Ill before eleva-
tion a temperature of melting lead, 635 F.
568 GEOLOGICAL SURVEY OF PENNSYLVANIA.
This operation, taking place throughout the whole 3000
feet of uplifted deposits, would have different results in the
different formations. In the sand and gravel deposits
(Potsdam, Medina, Oneida, Oriskany, Pocono, Pottsville)
the silica would be deposited between the grains and pebbles,
cementing them into a solid sheet or stratum of quartzite,
sandrock, or conglomerate.* The mud deposits would not
only be cemented, but cut with transverse and longitudinal
quartz veins. The lime muds would receive quartz veins in
abundance (as we see in the present surface sections), but
an infinitely greater number of calcite veins the supply
of silica being limited, and the supply of carbonate of lime
unlimited.
Meanwhile the tearing down of the elevated mass in the
regions of eternal frost went on, and formation after forma-
tion was washed away, continually producing a lower and
lower upper surface, until the present surface level has been
reached; and still the waste goes on, and still the surface
gets nearer and nearer to sea level.
The quartz veins of the swept away upper portions of the
mass, have been carried off with the rest, into the Atlantic.
But the tops of the quartz veins which are at the present sur-
face strew the ground with fragments underneath where they
once existed as solid veins. This accounts for the quanti-
ties of quartz fragments which are found lying on the pres-
ent surface in many places along the slate belt. For ex-
ample, on the Jordan in Low Hill township Lehigh county
the ground is covered with pieces of quartz (See D3, p. 124,
No. 187). A few miles south of this the veins of quartz
show in the slates (No. 190, p. 124). In most of the slate of
that region, quartz veins are abundantly numerous, and
some of them are quite large, like the one noted in D3, page
105, No. 96, at the Northampton Slate Quarry. The inser-
tion of the quartz between the laminae of a slate beds, that
is, following its lines of cleavage, is noted in D3, p. 122,
No. 175, at the North Peach Bottom Company's quarry.
* This is a fair way of accounting for the general quartzite aspect of the
lowest, hottest and most compressed formation No. I, as compared with the
higher, cooler and less compressed coarse strata of the Coal measures, No.
XIII.
CHARACTER OF FORMATION NO. III. 569
Flag stone layers occur in the Slate formation No. Ill,
and many small quarries have been opened along the slate
belt both in New Jersey and Pennsylvania; some of them
in connection with the roofing slate quarries (to be described
farther on) some of them having apparently nothing to do
with the roofing slate strata.
The sand deposits which made these flagstone layers, were
in some few places so coarse as to deserve the name of gravel
beds, or conglomerate rocks, although the pebbles in them
are all small. For instance, there is a pretty high ridge
of land two miles long south of Slatington in Lehigh county,
made rocky by loose fragments of a conglomerate.* But
where the rocks are exposed on the Lehigh river, they con-
sist of fine-grained sandstone, in a series of beds, none of
them more than four feet thick, 40 feet of them being visi-
ble and the rest concealed (See D3, p. 114, No. 142).
As a rule the sandstone beds in the slate belt are fine-
grained and thin-bedded. That they are very numerous,
and are separated by slate beds can be seen wherever the
belt is not too much folded. A very good exhibition the
purpose is made in Berks county, Albany township, where
the rocks are vertical. Here 500 feet of fine sandstones and
dark gray slates can be measured (see D3, p. 126). f
Sometimes both the sandstone and the slate beds all have
a greenish hue. Such a belt crosses the Schuylkill river
at Hamburg (D3, p. 128 to 133)4 Sometimes the slates
are olive colored or red, as already mentioned. Red slates
at various places along the Hamburg belt strike so as to
come between the sandstone outcrops. || The flagstone
strata quarried in the northeast corner of Perry township,
Berks county, roll so as to connect them with the red slate
exposures (No. 244). On the other hand the quarries about
* Dr. T. Sterry Hunt was so much impressed by this exhibition of coarse
and massive strata in the midst of the slate belt, as to imagine it a proof of
the far greater age of the formation, oil grounds which it is not necessary
here to discuss.
t See also p. 113, No. 133, on the Lehigh ; also, the Emanuel Church hill
in Northampton county covered with thin sandstones, p. 105 D3.
JSee also north of Seeberlingville, page 126, No. 198.
|| No. 236.
570 GEOLOGICAL SURVEY OF PENNSYLVANIA.
Shoemakersville do not seem to have a connection with the
red slate belt (No. 250, 251).
It looks as if the upper part of the slate formation No-
Ill furnishes most of the flaggy sandstone strata. There
are quarries in Berks county where the strata dip 65 to-
wards the south, in a line which would carry them west
into the spur of the North mountain. It is hardly possible
therefore to assign them a position more than 1000 feet or
so below the top of No. III. The flags taken out here (at
J. Gilt's, D3, No. 205) have rough faces, but dress up well.
It is not safe to conclude however that the flagstone
strata are confined to the upper part of the formation. They
may probably be found in all parts of it. The massive
flaggy sandstone outcrops south of Smiths ville in Berks
county are in the line of the red slate belt ; and yet there
are argillaceous limestone beds near them (No. 222, 223).
The mineralogical poverty of No. III.
The mineral wealth of the Great Valley is concentrated in
its southern or limestone belt. The northern or slate belt
is a farming district, of a fertility varying with the more
or less sandy quality of the different layers of slate which
come to the surface along narrow lines parallel to the sides
of the valley.
As the slate formation is several thousand feet thick
everywhere along the Great Valley ; it might be expected
that at least some of this huge series of layers would be
valuable to the mining interests of the country. Not so,
however. A few thin layers of poor limestone, or limy
slate alone appear to attract attention. Not a single min-
eral ore is to be found in the whole extent of slate belt of
the valley. Not even a bed of iron ore of any kind what-
ever worth shafting on has ever been seen or is likely to
be ever seen. The whole formation seems to have been de-
posited in deep oceanic waters, and what metallic salts were
deposited with the mud and fine sand remain disseminated
through the whole so as to be practically worthless in a
strictly mineral sense.
CIIVKACTKK OF FORMATION NO. III. i)71
Neither Oil nor Gas in No. HI.
Of late it has become necessary to give warning that
neither oil nor gas is to be found by any amount of boring
anywhere in the Great Valley.
Since the wonderful development of gas and oil at Lima
and other towns of Western Ohio and Indiana from the
Trenton limestone a thousand projects have been formed
to exploit the Trenton in Middle Pennsylvania by boring
down to it through the overlying slates. Some of these
vain projects have disregarded the commonest rules of pros-
pecting. For example, a well was bored north of Harris-
burg where the slates stand vertical ! No attention was paid
to the fact that the bore hole if vertical itself must neces-
sarily keep down always in the same rocks in which it
started, at least until they turned to take a north dip. It
would probably require a depth of between 10,000 and
20,000 feet for that well to strike the Trenton limestone
which crops out at Harrisburg ; where moreover it raises
no suspicion of oil or gas.
A little science is a dangerous thing. It usually resides
in words and names. The Trenton limestone has yielded
vast quantities of gas and some oil in Ohio and Indiana;
why not in Pennsylvania? Simply because the Trenton in
Ohio and Indiana lies on almost a dead level, and far enough
under ground (1000-2000 feet) to preserve its gas from es-
caping until bore-holes are provided. In the Great Valley,
on the contrary, as every farmer must know who opens a
quarry on his farm, the limestone beds have been upturned,
even overthrown, crushed, crumpled and broken into frag-
ments, and in that condition they reach the surface. Why
is the limestone belt scarce of water? Because the up-
turned and broken beds easily permit the rainwater to de-
scend to caverns which ramify beneath the valley in all di-
rections. Of course the ascent of oil, and still more of gas,
must be equally easy. If the Trenton in our State ever
had any store of the precious mineral it has lost that whole
store long ago. There can be none left. We have no evi-
dence that it ever had any.
572 GEOLOGICAL SURVEY OF PENNSYLVANIA.
No one but an expert geologist can compare two fields
so as to say that they are alike, or if they differ how they
differ ? Twin sons of one father may resemble each other
so closely that they pass for one another in common so-
ciety ; yet one may be ignorant and the other learned ; the
one a poor man and the other a millionaire. These are mat-
ters of original constitution, and still more of circumstance.
Just so with rocks of the same name, age and character,
but either deposited under different conditions, or subse-
quently subjected to different adventures. The flat lying
Trenton of the west is like the titled nobleman heir to
princely estate which has remained unspoiled and still
abounds for him. The Chambersburg Trenton is like a
younger son who has spent his patrimony, whatever that
was, in riotous living, and there is no more of it.*
Iron ore in the body of the Hudson river formation No.
JIJ, in its 500 miles extent of outcrop in Pennsylvania, is
almost unknown. The great limonite deposits of Ironton,
Moselem, and Leathercracker Cove are below the base of the
formation. And yet in Eastern New York beds of carbon-
ate of iron, partly crystallized into spathic iron ore, partly
weathered into limonite, are extensively mined, f
* "CHAMBERSBURG, PA., July 25, 1887. An effort is now being made in
this place to secure subscriptions for boring for natural gas. A number of
Chambersburg people who have visited the gas-producing districts of Ohio
believe that gas can be found underneath the surface here, because of the
marked similarity of some sections of this county to the gas fields in Ohio.
Subscription books are now being circulated over the town, and it is thought
the necessary amount needed for the experiment, about three thousand dol-
lars, can be obtained. Much interest is displayed in the project, for if gas
should be found manufactories would undoubtedly spring up in large num-
bers, and the future of Chambersburg would be almost beyond estimate."
fSee Siderite basins of the Hudson River Epoch, by James P. Kimball, in
Amer. Jour. Science, August, 1890, p. 155. They lie about a mile east of the
Hudson river, between Catskill and Germantown RR. stations, Avest of
Copake, in a range parallel with Taconic hills, and are plicated, some of the
anticlinals being overthrown and compressed westward (giving E. dips).
One section reads : Dense fissile slate, weathering white, 200'-f ; brecciated
sandstone (ferro-calcareons) 161' ; sandstone passing into conglomerate
(ferro-calcareous) 120' ; black slate and sandy shale (interbedded) 50' ; grits
(ferro-calcareous, seamed with calcite) 48'; carbonate of iron (clay iron-
CHARACTER OF FORMATION NO. III. 573
stone, siderite, sometimes spathic) 44' ; grey slate (weathering into drab
shale in the river bluffs) 662, to the bottom of boring No. 1 ; 1300 in all.
These lower slates, which, as Hall and Mather maintained (against Em-
mons) are Hudson river slates, have afforded Hudson river fossils to Mr.
T. Nelson Dale near Poughkeepsie. (Am. Jour. Sci. XVII, 1979, page 377.)
The ore body is a group of clay iron stone layers separated by more or less
ferruginous and calcareous shaly layers, the whole group varying from 8 to
60 feet, and evidently deposited in separate sea side lagoons, into which riv-
ulets from the hornblende gneiss country brought magnesian deposits.
574 GEOLOGICAL SURVEY OF PENNSYLVANIA.
CHAPTER XLVIII.
The roofing slate beds of No. 111.
These are what give an economical value to the forma-
tion, and redeem the slate belt of the Great Valley (geo-
logically speaking) from almost utter barrenness. Were it
not for its roofing slate quarries, one-half of the Great Val-
ley would be merely farming land, without mineral wealth
of any kind beneath the soil.
At present, however, there are no roofing slate quarries
in the Great Valley except at its eastern end in Lehighand
Northampton counties, and in New Jersey. It is even
doubtful whether or not the beds of roofing slate continue
to range through the formation west of the Schuylkill
river. The signs of their existence in Lebanon, Dauphin,
Cumberland and Fayette counties are very scanty, al-
though, here and there, what look like well laminated slate
beds do crop out ; as for example on Conodoguinit creek ;
where, however, the slate is spoiled with pyrites.*
It is, therefore, of considerable importance to ascertain
all the geological facts which bear upon the place of the
roofing slate beds in the formation where we know them
to exist, in order that their outcrops may be traced along
the valley where their existence has not yet been certified.
0??, the Delaware rive?' Formation No. Ill appears divisi-
ble into two series: an upper, and a lower.
TJie upper series, mostly consisting of thicker beds (from
one foot to many feet thick each) may be considered as oc-
cupying say 1540 feet of the whole thickness of the forma-
tion, f
The lower series, mostly consisting of thin beds (less than
*At Alton's mill. See Rogers, Geol. Pa., 1868, Vol. 1.
f Measured by Dr. Chance, and Mr. Sanders, from the base of No. IV in
the Delaware water gap down to Williams' old slate quarry.
THE ROOFING SLATE BEDS OF NO. III. 575
one foot in thickness) occupies the remaining say 3700 feet,
down to the limestone of No. II. *
But this subdivision of the formation is not founded upon
any other distinction than the one apparent fact that there
is a general tendency to heavy beds in the upper, and thin
beds in the lower parts of the formation. As for the mate-
rial itself there seems to be no good ground for the distinc-
tion. The whole mass, 5240 feet (and probably more) in
thickness, consists of beds infinitely various in thickness,
from 30 feet down to the hundredth of an inch beds of slate,
nearly all of the same uniform dark grey or bluish-black
color, both coarse-grained and fine-grained with occasional
beds of sandstone, which are not persistent but either run
out in a short distance or change into ordinary slate beds.f
In the section along the eastern bank of the Delaware
river (see page 554) two slate quarries are shown, one on
beds which come 1000 feet below the bottom sandstone of
No. IV; the other 2350 feet below it4
The interval of 1350' would represent the extreme thick-
ness of the roofing-slate zone in the formation if no other
quarry beds exists still lower, that is in the remaining 3000
feet of the formation down to the limestone. But of this
we cannot be sure, and in fact have reason to doubt, as will
presently appear.
On the Leliigfi river the section is not so simple, and
measurements are not so easy.|| Here a broken arch in the
slates has given rise to a fault, of unknown upthrow, half
a mile in front of the center of the gap, which cuts off all
* Measured from opposite Belvidere, up the west bank of the Delaware to
R. Shock's. See Report D3, Vol. I, p. 85.
f Dr. Chance remarks (D3, p. 150) that the foreman of the quarry on the
Xew Jersey side informed him that the diamond saiv used there for sawing
out slabs showed that the diamonds were more rapidly worn away by the
fine-grained than by the coarse-grained slate. These saws cut through the
slate at the rate of 1 inch in 5 minutes, 50 strokes forward per minute (D3,
p. 103).
% This section, constructed by Dr. Chance from data obtained by him in
making his contour map of the Water Gap, will be found on page 159 of
Report D3 ; the section along the west bank of the river on page 157; the
map in Report G6.
i| See Dr. Chance's section on page 554 above, and map in G6.
576 GEOLOGICAL SURVEY OF PENNSYLVANIA.
measurements down from No. IV after the first 1000 to
1500 feet.* Other rolls of considerable magnitude traverse
the slate belt between the fault and theSlatington quarries,
which are between 2 and 2| miles from the center of the gap.f
Then we get the crumpled roofing slate belt 810 feet thick;
which, although crumpled, can be measured with much cer-
tainy4 But the country south of Slatington, between the
quarries and the limestone is so full of folds that no meas-
urement of strata is possible; therefore the real height of
the lowest Slatington quarry-bed above the limestone, can-
not be made out.
All that we can say then is (1) that the uppermost part
of the great slate formation at the Lehigh water gap con-
sists of hard sandy slate beds, alternating with steel colored
fine-grained sandstones, beneath which come soft, shaly,
bluish-black slates; (2) that more than 1000' down from the
top of the formation lies a zone of roofing slates at least
1500' thick; and (3) that underneath this comes a vast rib-
bon-slate series.
The Slatington roofing slate zone is itself made up of
groups of beds of very various qualities, each group con-
sisting of irregularly arranged thick and thin beds, some
of which (both- of the thick and thin beds) have the roofing-
slate character.
This section could never have been made out but for the
extensive exploitation of many of the beds, several of which
are brought to the surface again and again by the rolling
* Even the thickness of the slate between No. IV and the fault is uncertain
owing to small rolls at the base of the mountain; but it cannot be less than
1000', nor more than 1500'.
f Mr. Sanders has endeavored to adjust these rolls in his long section,
underneath the Slatington section.
J See the Slatington section on plates L and LI, p. 554 above.
Dr. Chance expresses the opinion that between the fault at Slatington
the crumpling is so great as to suggest a possibility that the rooting slate
belt may be near the bottom of the formation (No. Ill) and therefore not
far above the limestone (No. II). But the continuation of the Slatington
belt westward near the foot of the mountain to be described directly, and
the measurements at the Delaware water gap already given, seem to make
it quite necessary to place theSlatington beds in the upper half of the forma-
tion (D3, Vol. I, p. 151).
THE ROOFIXG SLATE BEDS OF NO. III. 577
of the measures, as shown in plate L, on p. 544 above, the
most important consecutive section in the Great valley.*
Its great value consists in its proving conclusively, (1)
that the roofing-slate zone of the formation is (here at least)
1500 feet thick ; (2) that in this zone lie many different beds
of workable slate, some small, others of great size ; (3) that
although the zone is crumpled the roofing-slate beds hold
their special character over a space sufficient to allow them
to appear again and again at the present surface ; (4) that
the top of the zone is more than 1000' down from the top
of the slate formation No. Ill ; and therefore (5) that the
bottom of the zone must be a long way up from the top of
the limestone formation No. II.
The section has moreover a peculiar value for geologists
since (6) it shows what a small percentage of the whole
thickness of No. Ill its roofing-slate beds make, even where
those peculiar deposits make their best show. But to the
business world this is an unimportant consideration. Just
as a few five and ten foot coal beds in 3000 feet of coal meas-
ures, if accessible over an extensive region, can make the
fortune of a whole commonwealth, so a few ten and twenty
foot roofing-slate beds in 5000 feet of slate formation may
suffice to supply an extensive commerce; although all com-
parisons between the two cases in the matter of supply and
demand must necessarily be omitted. f
The roofing slate beds differ from the slate strata among
which they lie (1) by the special fineness of mud out of
which they were made ; and (2) by the special closeness
and evenness of the cross cleavage. All the slates of No.
Ill are more or less foliated ; but the roofing slates are
so delicately and evenly foliated (not parallel to the bed
planes, but across them at various angles) that they can
be split apart into school-slates, roof-slates, billiard-table
slabs, mantle pieces, and fine flags of various market values. ^
*And yet it is imperfect, inasmuch as its continuity is broken by three
concealed intervals of 100', 60' and 100' ; besides the indefiniteness of its up-
permost 400' "which includes large known workable beds."
1 30, 000 tons of slates is a fair annual shipment from the Slatington district ;
50,000,000 tons of coal from the anthracite region.
JSee the commercial tables in D3, p. 144 to 146.
37
578 GEOLOGICAL SURVEY OF PENNSYLVANIA.
The belt of quarries extends 30 miles across Northampton
and Lehigh counties. Numerous towns and villages have
sprung up along the belt between East Bangor within 5
miles of the Delaware river, and Slatedale 3 miles west of
the Lehigh river. Branch railroads have been made for
their service ; and new localities are being all the time ex-
plored. The belt is wide and the outcrops numerous. Some
of the quarries are within a mile of the North mountain ;
others (Chapman's for instance) are five miles from the
mountain, and two miles from the edge of the limestone
of No. II. Isolated quarries have even been opened within
a mile from the edge of the limestone belt. But all the
successful quarries seem to belong to the Slatington zone,
the outcrops of which repeat themselves in parallel lines,
with alternate north and south dips, over a geographical
belt of surface varying in width from one to three miles
according to the number of the rolls and the flatness or
steepness of the dips.
But as yet there is no proof that any one of the quarry
beds extends for 30 miles or for 10 miles along the zone.
The continuance for any distance of the special roofing
slate quality of any layer or group of layers in the slate
formation is only determined for the individual quarries,
or immediately adjoining quarries. It is not certain there-
fore that a fine quarry bed may not exist along a line of
ordinary and worthless layers. Every exposure should
therefore be tested for itself. The place of a coal bed in
the coal measures is a good guide for the coal prospector ;
but there is as yet no satisfactory proof of the fact that the
place of a slate bed in the section (if discoverable) is a sure
guide for the slate prospector.
Even the continuance of the Slatington zone as a whole
along the Great Valley westward beyond the Schuylkill is
a matter of doubt. Roofing slate quarries have been opened
in the northeastern part of Berks county which undoubt-
edly belong to the Slatington zone ; but no roofing slate
quarries have been opened in western Berks, in Lebanon,
Dauphin, Cumberland or Franklin counties. The expla-
nation of the fact may be a geological one, viz : that the
THE ROOFING SLATE BEDS OF NO. III. 579
Slatington zone thins away and vanishes in Berks county,
going west. Or the explanation may be a financial one,
viz : that exploration confines itself to the neighborhoods
in which capital has been planted along the lines of already
constructed railroads, etc., within near and easy reach of
the principal markets. Thus far, no inducement for ex-
ploring the slate belt of the valley has been sufficiently
strong to divert capital invested in the roofing slate manu-
facture into new channels and to distant districts. The cost
of testing the value of a new coal opening is inconsiderable.
The cost of testing the real value of a slate outcrop for roofing
slate quarry purposes is a serious consideration. It requires
the eye of an experienced slate miner to pass judgment
upon a slate outcrop as to whether there is a likelihood that
the bed will furnish roofing slate at a considerable depth
underground ; and the actual profitableness of a slate quarry
is never known until extensive quarrying has been done.
This the great number of abandoned quarries sufficiently
demonstrates.
Even where the qualities of fineness and foliation (split-
ability) is possessed by a roofing slate bed, it is sometimes
made worthless by a want of evenness. The excessive
crumpling of the slate belt applies sometimes to the mi-
nutest details of a quarry, and quarries have been aband-
oned because the slates are twisted or warped, and there-
fore worthless.*
The ribbon structure of the roofing slate beds is their
most striking peculiarity. The ribbon pattern seems to
cross the beds ; but in fact it shows the real bedding of the
original deposits, and has been itself subsequently crossed
by the cross-cleavage, or slaty foliation, produced by the
tremendous side pressure at the time of the folding of the
formation. f
The ribbon pattern is made by the different colors of
* The Flynn quarry is said to have been abandoned for this reason (see
D3, p. 104, 109). See also the bent slates in the Blue Vein quarry, p. 117, No.
1566. On the Jordan the cleavage is described as curly (p. 124, No. 184).
fSee D3, p. 85; and Rogers' Geol. Pa. 1858, Vol. I, p. 248.
580 GEOLOGICAL SURVEY OF PENNSYLVANIA.
the original muddy deposits, some gray, some black.* The
ribbons at the Newville slate company's quarry are " tight
and some of them jet black" (D3, No. 119). Those at the
Blue Vein quarry when they get under 30' or 40' of cover
become tight (No. 1566). An expert slate miner judges of
the value of slates partly by its ring.-\
Westward extension of the roofing slates.
West of the Lehigh river the Slatington roofing slate beds
run on towards the Schuylkill. The old Diamond slate
quarry 4 miles west of Slatington (3 miles from the North
mountain) was worked to a depth of 250 feet and abandoned.
A quarry near Pleasant Corner (7 miles) is abandoned. The
Laurel hill quarry and Lynnport quarry (11 miles) are each
60' deep4
Near the Berks county line (15 miles) are the New Slate-
ville quarries, on the two sides of a roll, both on a bed 4'
thick and both abandoned. On the other side of the
county line in Berks county the Centennial quarry is 80'
deep ; and near it an abandoned quarry on a 20' bed. West
of this no roofing slates have been found, but flagstone
quarries have been opened. ||
There arises then a practical question : how is the
roofing slate sub-division of the slate belt to be recognized
along the valley ?
(1) First, by its distance from the top or bottom of ths for-
mation, as described above, /. e. 1000' to 2000' beneath the
sandstone No. IV of the mountain crest, 2000' or 3000'
above the limestone. As the latter measurement is almost
* The best at the West Washington quarry is called "the grey bed" (D3, 98).
f Thin-bedded slates, dark blue, with a good ring (p. 113, No. 135). The
slates have a good ring, dark color and even cleavage (p. 114, No. 146). The
slates lei't on the pile are thick and have a poor ring (p. 109, No. ] 14) etc.
J The one lies one mile from the mountain the other two miles ; at the
first the dip is vertical which if it lasted all the way to the mountain would
make the bed 5000' below the sandstone; in fact the distance is much less.
These are 6000' from the sandstone outcrop.
[| In Albany township west of Kempdou ; in Perry township (half-way
between Leonhartsville and Virginsville) where 3' flags 10 feet long are
obtained ; and near Shoemakersville.
THE ROOFING SLATE BEDS OF NO. III. 581
an impossibility on account of the folds in the middle
slate limestone zone of the valley the former measurement
(i. e. from the sandstone No. IV down) is the only one avail -
ble. When the dips in the foot hills of the mountain are
10 to 20, the roofing slate belt must be looked for a mile
or so from the mountain ; when the dips are 50 to 60, it
must be looked for close to the foot of the mountain slope.
But it must be remembered that the whole breadth of the
slate belt is so folded, that the roofing slate zone (if it exists)
will come to the surface several (or even many) times be-
tween the mountains and the edge of the limestone.
To show how important this consideration is we must go
back for a moment to Lehigh county. There are three places
west of the Lehigh river where roofing slate quarries have
been worked nearer the edge of the limestone than the
Slatington quarries are to the mountains; thus, in N.
Whitehall township (2m. S. W. of Laury's, P. O.) the North
Peach Bottom quarry (250x200' long and 90' deep) is only
f mile from the edge of the slate. Here the beds are flat,
but in a downfold, and therefore cannot lie more, than 2000'
above the limestone.
Again in S. Whitehall township between Orefield and
Crackenport is an abandoned quarry on Huckleberry ridge,
a long downfold (synclinal) of slate between two areas of
limestone and only f mile wide. Although the slates
are here vertical, there is only room for 1320' on both dips
or 760' on each dip. It seems as if we must insert a roofing
slate zone near the lower limit of the foundation.
Again, east of Seipstown, and 4 miles west of the last,
there is an old quarry not far back of the limestone edge,
dip 70. But here there is room enough for perhaps 2000'
of distance from the limestone up to the slate,
The truth seems to be that the main belt of roofing slate
runs along more than half-way up in the formation ; but
that there exists beds of roofing slate in the lower half of
the formation, some of which, in some neighborhoods, may
possess commercial] value. And this explains a fact first
noticed by the First Geological Survey of Pennsylvania,
and published by Prof. Rogers in his final report, Vol. 1,
582 GEOLOGICAL SURVEY OF PENNSYLVANIA.
page 260: After saying that "in no part of the slate for-
mation" from the Susquehanna to Maryland " have the
strata the structure and cleavage to produce roofing slate,
he adds : ' ' The nearest approximation to that useful variety
yet seen occurs in the bed of the Conedoguinit, above
Alter' s Mill, where the rock is traversed by cleavage-
planes of tolerable regularity, but its usefulness is destroyed
by its containing sulphur et of iron." As the Conedoguinit
runs along the southern edge of the slate belt, and some-
times cuts a little into the limestone belt, these cleaved slates
must belong to the lower part of the slate formation No. III.
So in Franklin county 1 miles southeast of Orrstown on
the road from Orrstown to the railroad, there is a fine road-
cutting 30 feet long by 15 feet high which showed the
folded slates with a roofing slate cleavage at right angles
to the folds and the accompanying local map shows how
close the locality is to the southern border of the slate belt,
and therefore in the lower part of the formation.
Red slate, which is not rooting slate, has not been ob-
served in Northampton county ; nor in Lehigh county ex-
cept within a few miles of the Berks county line 1 m.
N. E. of Seiberlingsville in Weisenburg township No. 197,
D3, p. 155); but in Berks county it is frequently noticed
by Mr. Sanders, e. g. in Albany township, west o f Kemp-
don (No. 206) red slate spotted with green ; half a mile S.
of Kempdon (No. 208).
Notes on the Bangor slate belt.
By R. M. JONES.
At my request Mr. Jones addressed me the following
letter, embodying in his own way valuable information,
which it is natural that he the pioneer of this important
industry alone knows, or knows better than any one else.
BANGOR, October 10, 1S8J.
"According to my promise, I write to you concerning the
slate interests of our country, and particularly of Northamp-
ton countv
THE ROOFING SLATE BEDS OF NO. III. 583
"The slate belt of Fail-haven and Paultney, Vermont, runs
through Middle Granville and Granville Corners in Wash-
ington county, N. Y. to Pawlet Wagen. In all the above
named places there are large and extensive quarries in full
operation. In this part of the belt the slates are of various
colors, viz: purple, green and red. This belt thence runs
through North Hoosick and Hoosick Falls in Rensselaer
county into Columbia county, N. Y. In this county the
stratum makes a large dip which runs under the bluestone
of the Hudson river division below Kingston, N. Y. This
dip is over sixty miles in extent. The slates are nothing in
all this distance but a conglomerate slate of no value what-
ever as slates. The finest slate of any value we will meet in
this stratum is in Sussex county, N. J., which is of an in-
ferior quality, properly belonging to the Chapman division,
what is called the wavy or ribbon slate adapted only for
local trade. In the north part of the stratum what are called
the Bangor slates are considered in England and the Conti-
nent (where they know what to look for in slates) the trade
mark of America, so much so that all slates shipped from
this country are called Bangor slates to gain credit and
reputation. The slates of Sussex and Warren counties
N. J. do not amount to much. We have made a close ex-
amination of the strata between the Delaware Water Gap
on the Jersey side through Warren and Sussex counties,
N. J., into Orange county, N. Y., and we find the article of
poor quality, more of the earthenware nature than slates,
lacking the principal quality of the right kind of slates for
roofing or school slates, which is toughness. There is an old
quarry at the Delaware Water Gap, one on the Jersey side of
the river, opened over sixty years ago by a gentleman named
O. Evans, a native of Carnarvonshire, North Wales. He
worked the quarry successfully for a number of years until
his death, and accumulated considerable property and
money through the working of this quarry. On the west
side of the Delaware river near the gap, nearly opposite the
Evans property, is another slate quarry near the village of
Slateford, in Northampton county, Pa. This is supposed to
be the oldest slate quarry in America, the quality of the
584 GEOLOGICAL SURVEY OF PENNSYLVANIA.
slate is the same as in the Jersey part of the stratum ; the
stratum makes a southwest dip here of over live miles in
length, appearing and outcropping at the Boyer farm and
other places in that locality in that neighborhood. The
quality of the article in those places for roofing or school
slate is only ordinary. This stratum runs southwest through
the Brushy Meadows Valley, East Bangor, Bangor, Pen-
argyle and the Wind Gap. And right here I would say
that the great slate center of our state is destined to be be-
tween East Bangor and about one mile southwest of the
Wind Gap ; a belt of slates near ten miles in length from
northeast to southwest, and about one mile in width or thick-
ness from north to south. We have a number of quarries
opened and in course of opening in this section. The prin-
cipal quarries are the following: First, in East Bangor the
celebrated Seek-no-further property, the old Delp property
the Meyers, Bray and Short property, the Star slate quarry,
the Standard slate property, the Bangor Central, the Howell
property, the New Bangor quarries, the Old Bangor quar-
ries, the Bangor Royal, the Bangor Unison, the North Bangor
and the Washington slate property. All of these quarries
except the little Washington are in full operation ; and
there is more slate made in this section of the country than
in any other one part of the United States. And then we
must take into consideration that all these improvements
are of a very recent date. R. M. Jones started nearly all
these quarries since July, A. I). 1865. When he started the
Old Bangor quarry on the first of August, 1866, Bangor
under the name of the New Village contained less than
twenty inhabitants. Now it is made into a borough of near
three thousand souls ; and if all who work in the borough of
Bangor would live in it we would have a population of over
nine thousand inhabitants. Bangor was named after old
Bangor in Wales, and is considered by all the finest mining
town in the State of Pennsylvania.
"Two miles and half northwest of Bangor on this slate belt
is the town of Penargyl ; there is a very geart body of large
beds of slate in this locality. The cleavage in this place is
mostly horizontal, the ribbons pitching from 35 to 45
THE ROOFING SLATE BEDS OP NO. III. 585
degrees southeast. When we talk about a bed of slates we
mean that portion of the rock that lays between ribbons
or black streaks that run across the cleavage and grain of
the slates. These streaks only occur in this stratum in
the slates of New Jersey and Pennsylvania ; there are no
rubbons or black streaks in this stratum in the States of
New York, Vermont or New Hampshire, nor Virginia ; but
we find the ribbon in part of the State of Maryland near
the Point of Rocks. There is much difference in the quality
of these ribbon slates. In some parts of the belt, especially
in the north part of this stratum the ribbon slates will not
do for roofing slate ; but the south part of the belt is well
adapted for roofing as a second quality of slates ; and the
fact of the matter is that all ribbons or wavy slates are
nothing more than second grade of roofing materials. Still
there is a large quantity of this kind of slate recommended
by architects in your city and some parts of the adjoining
counties. Some do it from ignorance of the true quality of
slates ; but the most of our architects specify this article of
roofing because it pays them to do it ; and th only way a
second quality of slates of this kind has succeeded so well
is by having percentage paid to that class of men who specify
what material shall be used for the buildings. When such
stuff is sent to England where they want first quality of
slates they are not accepted.
"At Pen Argyl two and one-half miles from Bangor there
are some very fine slate quarries opened by Jung & Co.,
John & Rich, Jackson & Co., Stean, Jackson & Co. and
the Albion Slate Company, and Henry Fulmer. All these
quarries contain large beds of slates ; and slates can be pro-
duced in this section of the slate belt at from thirty to forty
per centum cheaper than at other localities on this stratum ;
because from a large bed of slate we can make large sizes of
slates. For instance, it only takes 98 slates of 24 x 14 to make
a square of slates (that covers 100 feet of roofing); while it
will take 533 slates of 12 inch by 6 inch slates to make a
square (or 100 feet) ; and while the mechanics are making
one square of 12x6 they will make five and one-half squares
of 24 X 14 inch slates. Hence the importance of selecting slate
586 GEOLOGICAL SURVEY OF PENNSYLVANIA.
properties containing large beds of slate. In this part of
the stratum the slates are not adapted for school slates ; but
in the south part of this the mountain strata is where the
school slates can be procured. About one-half a mile south
of Pen Argyl on the Bangor and Portland Railroad a large
deposit of a very fine quality of school and roofing slates
was discovered by R. M. Jones of Bangor, Pa. at a place
called the Grand Central quarry which are of a fine texture
and very dark color. Also Mr. Jones has discovered a large
plant in the north part of the slate stratum of the Pen
Argyl division, which is about three miles southwest from
Pen Argyl. This is a large field for enterprise. The slate
stratum pitches like the waves of the sea. The general dips
are about three miles. And right here I would like to draw
your special attention to the fact that the same bed of slate
loses its strength and toughness in its outcropping. On the
down dip the article will split from the side across the grain
or cleavage readily, but on the outcropping it will not split
across the grain or cleavage at all. About one mile from
the Wind Gap southwest, the position of the ribbon changes
to nearly a vertical position, and keeps on that way princi-
pally all through Northampton county to the Lehigh river
at Walnutport ; and the cleavage dipping about seventy-
five degrees southeast. The stratum is much conglomerated
from the first mentioned points to the Lehigh river. There
are a few places in and between the aforesaid points where
good quarries are and may be opened. At the Little Gap
Hower & Son have a good slate property. About one and a
half mile southwest of the Howard quarry a good quarry
may be opened on the same beds. At Berlinsville there are
several quarries opened and in course of being opened. At
a place called Himbach several good quarries within about
two miles from Walnut Port are well adapted for both
school and roofing slates, but there is considerable con-
glomeration in the slate belt from the Wind Gap to Walnut-
port, and investments should be made with great care and
close examination of the premises.
''The whole width of the slate belt from about one mile
above Siegfried's bridge on the Lehigh river to the Lehigh
THE ROOFING SLATE BEDS OF NO. III. 587
Gap is near ni;ie miles, but in all that distance there is
not over three quarters of a mile of what might be termed
a No. 1 article of slates adapted for school and roofing
slates. This commences about a quarter of a mile below
the Queens hotel at Walnutport and runs up the river
towards the Lehigh Gap less than half a mile north of
Walnutport as we proceed northeast from Walnutport.
Beyond Berlinsville the good stratum is about a quarter
of a mile wider. From the Little Gap to the Wind Gap the
belt is much conglomerated and full of posts and crystals,
which makes it a very dangerous field to operate in."*
*Mr. Jones' letter is brought to a close with a beautiful verse of poetry in
the Lower Silurian language of Wales, the age of which is not quite so remote
as that of the slate belt, but nevertheless has this in common with it, that the
vowel foliation crosses and obscures the original consonantal stratification.
I would gladly give it here had I any friend at hand learned enough to verify
the orthography.
588 GEOLOGICAL SURVEY OF PENNSYLVANIA.
CHAPTER XLIX.
The slate quarries of Northampton and Lehiqh counties
in 1882.
In 1883, Mr. Sanders' notes on the quarries of the slate
belt were published in report D3, Vol. I, pages 86 to 133.
No subsequent resurvey of the belt could be made, as the
corps were fully occupied in other counties. New opera-
tions, especially upon the Lehigh river above Slatington,
deserve description for which I have no data. The follow-
ing list and short mention of the quarries as they were be-
fore 1883 will suffice to show the character of the belt.*
In Northampton Co., Upper Mount Bethel township.
1. Washington Brown's Quarries, on the slope of the
mountain overlooking the Delaware, recently opened ; 75 X
75x40 feet; 600' below the Oneida sandstone; dip 25 N.
40 W. cleavage flat. The slates have a good color and
are smooth.
2. John Morrison's Quarry, at the foot of the steep
slope of the mountain, 800 to 900 feet below the Oneida ;
opened in 1877 ; 150x100 feet ; five to fifteen of Drift on
top of the slates, which are decomposed under the drift ;
dip 20, N. 40 W., cleavage flat. The beds are four feet
and under in thickness.
?. J. W. Williams' Quarry, half a mile northwest of Slate-
ford ; 150x150x100; 30 to 50 feet of Drift on top, with
boulders 2 feet in diameter ; thickest bed 4 feet ; dip 20,
N. 10 W. ; cleavage 2, S. 10 E. At the factory the
ribbon slate is seen in the bed at the creek fifty feet below
the quarry. f
*The numbers are those in D3, and are found on the county maps of the
D3 atlas. They begin at the Delaware river and run in a general westward
order across Lehigh county into Berks.
fThis was the first slate quarry opened in Pennsylvania viz: by Mr.
Williams auout the year 1812. It is described in Prof. H. D. Rogers' Geol-
ogy of Pennsylvania, Vol. I, p. 248 as follows ; but the/cm^ is not now vis-
ble, being buried under water and debris.
SLATE IN NORTHAMPTON AND LEHIGH COUNTIES. 589
4. Emory Pipher quarry, a few hundred yards west and
slightly below Morrison's quarry; abandoned; 200x100
feet ; beds seen small ; dip in the south and central part
of the quarry flat ; at the north edge 20, N. 40 W. ;
cleavage 20 south.
J. Snowden quarry. (Fig. 1 p. 548) This quarry owned
by H. P. Jones is 500 yards northwest of Williams quarry ;
150x150x40 ; 15' of drift on top. Two of the largest beds
are 14 and 12 feet thick ; cleavage 26 south. At the north
side of the quarry there is a fault showing, probably the
same fault as described by Prof. Rogers in the Williams
quarry ; beds south of the fault dip 40 north. Product in
1882 about 150 squares a month. Started in 1870.
6. The quarry (Fig. 2) worked by William Manus of
Scran ton, on Peter Fry's farm ; 300x100 feet and full of
water ; no large beds to be seen.
7. L. Or one" s farm, \% miles north-east of East Bangor,
a small abandoned quarry, 50x50x15; dip 20 N. 40 W.,
with flat cleavage; largest bed 2 feet thick; cleavage twisted.
8. J. Oyer's farm, li miles north of East Bangor;
100 x 100 feet, full of water ; beds 3 feet thick and less ; 10 feet
of Drift; dip 10. N. 40 W. ; cleavage 20. S. 20 W.
9. Opposite Belvedere. The contact of the slates and
limestones on the Delaware river shows by a high ridge.
The dip is 70, S. 20 E. and the cleavage 25, S. 20 E. The
same dip shows for three quarters a mile up the river.
The slates are thin bedded, compacted together, making
solid beds, in some cases 10 feet thick, between loose rib-
bons. From the river road up north until the road lead-
ing from Centreville to Porterville is reached, nothing but
ribbon slates show.
11. C. Wolfs farm on Martin's creek half a mile east of
the township line, a small excavation ; dip 15, N. 40 E. ;
cleavage 60, S. 40 E. ; ribbon slates.
12. East Bangor quarry No. 3, Bry & Short; north
side of the railroad, east of the wagon road leading north
from East Bangor ; 150x50x50 ; dip 5, S. 40 W. ; cleav-
age 20, S. 10 W. ; beds rather small.
13. Old East Bangor quarry. Fisler & McKean ; across
590 GEOLOGICAL SUKVEY OF PENNSYLVANIA.
the road from East Bangor No. 1 ; 250x150x50, with water
in the bottom; dip flat; cleavage 20, S. 10 W. ; largest
bed 3 feet thick.
14. East Bangor No. 2. Bry & Short, 300 yards west of
the old East Bangor quarry; 200x450x60; dip 10, N. ;
cleavage 20, south ; largest bed four feet.
15. East Bangor No. 1. Bry & Short, between East
Bangor No. 2 and the railroad ; 250x200x100 ; dip 20, N.
20 W. ; cleavage 20, S. 20 E. ; beds 16, 10 and 11 feet in
length along the cleavage.
16. Star quarry. Major Aims, 500 feet west of the East
Bangor No. 2; 200x200x50; cleavage 20, south. There
is an old quarry (not being worked) just south of this, on
the same beds as the East Bangor No. 1.
Washington township.
Colon Aims' quarry, close to the township line, on the
north side of the creek ; 100x50x40 ; with 10 to 20 feet of
Drift on top ; dip 25, N. 40 W. ; cleavage 20, S. 4 E. ;
beds all small. Some of the slates are made from single
beds, while others have two or more beds in them. The
slates made from the ribbon slate are mostly bent ; others
are good except a few which are slightly bent.
17. Bangor Central quarry, % mile west of the township
line on north side of creek; 200x100x40 feet deep; dip
25, N. 40 W. ; cleavage 10, S. 40 E. ; make slate out of
single beds, and from two or more beds ; some of them
slightly bent ; beds all small,
18. Bangor Old quarry, 500 feet west of the Bangor Cen-
tral ; side hill cut, 50 feet deep at the face, with from 15 to
30 feet of gravel on top ; dip 25, N. 40 E. ; cleavage 15,
S. 40 W. ; slates made from single beds and from two or
more beds ; some much bent.
19. Powell's quarry, on south side of railroad, f mile east
of Bangor ; side hill cut, 300 feet long, by from 50 to 100
feet broad, and 80 feet deep ; dip 25, N. 40 W. ; cleavage
15, S. 40 E. ; 5 to 15 feet of *Drift on top ; largest bed 4
feet. The slates on the dumps are made from one or more
SLATE IN NORTHAMPTON AND LEHIGH COUNTIES. 591
beds ; all of these with two beds in them were bent, some
few of the others were also bent.
20. Bangor Valley quarry, a few hundred feet west of
Powell's quarry; 200x150x50 feet; dip 20, N. 50 W. ;
cleavage 10, S. 50 E. ; 5 to 10 feet of Drift on top ; largest
bed 3 feet ; quarry on top of the Bangor axis ; slates above
the Bangor slates.
21. Bangor quarry (Fig. 3), mile east of Bangor ; 600 x
400x130. A synclinal axis passing through the center of
it, about 70 feet below the surface ; the plane of the axis
dips 5 to the north, the cleavage also dips 5 north. There
is 30 feet of Drift on top of the south side of the quarry ;
largest bed 9' 6" ; synclinal axis pitches to the west, being
the same synclinal that shows in the Washington quarry
and the Bangor Union. The slate in the north end of the
quarry would come to the surface at the railroad, on a line
between the Washington and Bangor Union quarries. The
slate on the south side of the quarry probably shows in
the Washington quarry. There are 60 men engaged in quar-
rying, besides the drivers, engineers and splitters. The
quarry is worked by horses and carts and also by three cable
derricks run by separate engines. There are 42 shanties in
operation. (1882.)
82. Washington, quarry (Fig. 4), Fulmer & Wagner, just
west of the Bangor quarry ; 150 X 100 ; reported 70 feet deep ;
20 feet of Drift on top ; cleavage 12, N. 30 W.
23. Bangor Union quarry is some 250 x 250 x 130 feet deep
at the deepest place, with from 11 to 20 feet of Drift on the
surface ; largest bed 4 feet thick. The synclinal axis
which shows in the Bangor quarry also shows in this one,
but the plane of the axis dips slightly to the south instead
of to the north as in the Bangor. The quarry is worked by
5 cable derricks, which supply material to 20 shanties. The
derricks are run by one engine, which, working a line of
shafting, connects with the cable derricks by conical friction
wheels. The quarry is running on roofing and school slates.
Those slates made just below the turn of the axis are bent ;
the others are good. The beds in the quarry are tight and
some of the slates are made across the beds. (1882.)
592 GEOLOGICAL SURVEY OF PENNSYLVANIA.
24- North Bangor No. 1 ; south-east corner 200 feet west
of the north-west corner of the Bangor Union ; 200x200x
40 ; 20 feet of Drift, and they make slate one foot below
it ; cleavage 10, S. 30 E ; dip 45, S. 30 E. ; two largest
beds 4 feet ; there is a bed measuring 10 feet along the
cleavage ; at the south end of the quarry this 10 foot bed
has two feet of rock on the top of it, making only 8 feet of
it workable. The beds show all the way across the floor of
the quarry ; all of them are under 4 feet in thickness.
.25. North Bangor No. 2, a few hundred feet north of
No. 1 ; 150x100, 40 feet deep ; dip 35, S. 30 E.; cleavage
15, S. 30 E. ; beds under 4 feet ; I was told there were two
measuring 12 feet in the quarry, but could not see them as
it was full of water.
26. North Bangor No. 3 (Fig. 5 p. 548 above), 200' north
of No. 2; side hill cut 150x200x100; of irregular shape
and worked at the centre of the synclinal axis ; plane of
axis dips 15, S. 30 E. ; cleavage dips the same.
27. Jacob O. Pystef 1 s quarry, one and a half miles S. E.
of Bangor, 50x50x20 feet ; cleavage 30, S. 30 E.
88. Two miles S. E. of Bangor, on the east side of Mar-
tin's creek, on P. Pysher's farm, is a small cut 50x30x30 ;
dip 10 N, ; cleavage 30 S. ; slates all thin bedded ribbon
slates.
29. True Blue slate quarry (Fig. 6, p. 548), on Martin's
creek 1 m. E. of Factoryville; irreg'ular, averaging about 150
X 150x80 ; at the face the structure is shown as in the fig-
ure ; in the cut the cleavage is 25 S. parallel to the plane
of the two axes. At the bottom of the cut a quartz vein
shows one foot thick dipping 25 S., spoiling the cleavage
for a short distance on each side of it. On the south-east
corner of the quarry a few small quartz veins show. The
slates are all thin bedded ; have a good metallic ring, but
those that have been exposed on the dump show signs of
bleaching. The quarry not being worked in 1882.
Lower Mt. Bethel township.
30. On Little Martin's CreeJc^ half a mile above the
school-house, ribbon slates show dipping 70 N.. with a
SLATE IN NORTHAMPTON AND LEHIGH COUNTIES. 593
cleavage of 25 south. A quarter of a mile below the school-
house ribbon slates show with a flat dip and cleavage of 25,
S. 10 E.
32. In the bottom of a small hollow half a mile north-
west of Martin's Creek Post Office, there is a small aban-
doned quarry of ribbon slate ; dip 45, N. 20 W. ; cleavage
S. 20 E.*
Plainfield township.
3f. Hull's quarry, A. & O. T. Hull, 1 m. N.E. of Pen Ar-
gyl; 250xl50x- q O; 15' loose slate on top; dip at surface
68, S. 10 E. but steeper in the lower part of the quarry ;
cleavage 15, S. 10 E. ; two largest beds 10 and 7 feet thick ;
blocks come out even and split and sculp well ; not as much
waste as in the average run of quarries.
38 Pennsylvania quarry, at north end of Pen Argyl ; 250
X200 feet ; dip at N. end 55, N.3<) W., gradually flattening
southward ; cleavage 25, S. 30 E. Seventy feet from the
north end is a 20 foot bed ; some distance below this a 6 foot
bed ; rest of the beds smaller ; most of the ribbons tight.
39. Jory quarry, N. A. Jory &Co., 400x200x80 ; worked
in the center of a synclinal; dip slight in center of axis ;
plane of axis vertical ; cleavage horizontal.^
*Just above the mouth of Martin's creek the contact of the slates and
limestones shows. The slates foi half a mile up the creek are seen dipping
slightly towards the north, and are very much contorted. The cleavage ia
Hat, the beds are small but not ribbon slate. Just east of where the road.
from Martin's creek crosses Mud run, vertical black slates show with a
horizontal clearatje. The largest bed is two feet thick. On the road lead-
ing down Mud run between Hutchinson <fe Kahler's an anticlinal shows in
the slates. The slates are ribbon slates. In the samecut two reins of quartz
show dipping steeply to the south. Just west of Hutchinson's ribbon slates
show dipping N. 20 W. Cleavage 40, S. 20 E.
The contact of II and III enters Forks township a few hundred yards
south of its north-east corner, and passes through the township in a south-
westerly direction, crossing Bushkill creek into Palmer township west of
the Lutheran church at Churchville. In Palmer township the junction
line is not well shown. The area covered by slates is a strip across the nor th-
em portion of the township half a mile wide.
*This is the only quarry in which the cleavage can be seen at right angles,
or any considerable angle to the plane of the axis. The beds worked are
not large, but the cleavage making such a large angle with the bedding,
large blocks can be taken out They were making about 25 squares a day
with 4 shanties at the time of visiting the quarry. There are two spar der-
ricks worked by horse power.
38
5&4 GEOLOGICAL SURVEY OF PENNSYLVANIA.
40. Jackson's quarry ; 300x200 by about 100 feet deep ;
ttoo cable derricks, run by two double-cylinder engines ; 4
shanties averaging about 4 squares a day to a shanty ; slates
come out in good sized blocks, some of them 20 feet long ;
split and sculp well and fracture rather well.
41. .Robinson quarry, Stephen & Jackson, 400x200x80 ;
dip 28 south ; cleavage flat ; beds 25, 16 and 12 feet long
along the cleavage ; one cable derrick and several spar
derricks, run by horse power; 16 shanties in operation
(1882).
4. West Washington quarry, Fulmer and Jackson,
150x75 feet and 50 feet deep ; 25 feet of loose material on
top ; same bed as at the Robinson and Jackson quarries ;
best bed is the gray bed, which is also worked in the Jack-
son ; dip 48 south ; cleavage flat. *
43. H. Young 's far in, \\ miles west of Blue Mountain
Post Office ; a small cut in the hill side showing slate beds,
the largest of which is 2 feet thick ; dip 15, N. 20 W.
cleavage 15, S. 20 E.
44- Delabole quarry, of Factory ville ; 150x100; dip 80,
S. 30 E. ; cleavage 25, S. 30 E. ; all thin bedded sfates ;
beds large between the loose ribbons.
46. Pine Grove quarry, Edleman & Co., 200x150x130;
dip 60 N. ; cleavage flat ; slates all thin bedded ; make
besides roofing slate, flagging and fence posts.
47. White Oak quarry, T. Reed & Co., 150x100x100 ; dip
20 N. ; cleavage 10, S. 45 W. ; joints vertical, and in one
part of the quarry 80 feet from joint to joint ; slates all
thin bedded ; average about 3,000 squares of slate a year.
48. Samuel Seams' quarry, 1 m. ^N". by E. of Belfast ;
200x200x80 feet ; dip 20 to the north; cleavage flat or
slightly to the west ; slates all thin bedded ; largest bed 30
feet between loose ribbons ; other beds worked are 16, 12
and 4 feet between loose ribbons ; make about 4, 800 squares
* At S. end the top bed is 10'-thick, then follow downward 6 beds in 2 feet,
there is a 2 , 3", and a 7" bed and 1' 8", 2', 3", 1' 6", 1' 3", 7", 1' 6", 10", 9", 1'
7", 2", 1' 10", 9", 15' 6", 6', 3', 3 beds in 6", 3', 7", 6", 2', 9", 1' 3", 4", 1' 2",
11'', 3", 1' 1", 1' 5", 6", 10' 2" the gray bed, 30 feet of beds 2 feet and under in
thickness, 4'. The 10 foot bed, at the top of the quarry has 2 feet of rook on
top, a dark fine-grained sandstone. The gray bed has also rock on top.
SLATE IN NORTHAMPTON AND LEMIGH COUNTIES. 595
a year ; also flagging and fence posts ; worked 'by two cable
derricks run by one engine.
49. Young, Duck & Co.' s quarry, 1 mile W. of Kessler's
Post Office ; fall of water ; dip 20 north ; cleavage flat ;
slates all thin bedded.*
50. James Deck's quarry, 100x100 feet, full of water;
dip 15 north ; cleavage flat ; slates all thin bedded.
52 Davidson's quarry, I m. S. W. of Kessler's Post
Office, 150x100, full of water ; abandoned ; dip 60, N. 20
W. ; cleavage 20, S. 20 E. ; slates all thin bedded.
53. Belfast quarry, % m. S. of Davidson's quarry, 150 x
75 ; full of water ; 10' stripping ; slates thin bedded ; dip 20,
N. 20 W. ; cleavage 20, S. 20 E.
Bushkill township.
60. Hughes Bros, quarry, f m. S. E. of Jacobsburg ; 100 x
150x60 ; average dip 70 ; cleavage 20 S. ; slates all thin
bedded ; longest distance between loose ribbons 25 feet ;
makes about 1,500 squares a year, and have made as high
as 8 squares a day to a splitter, but 4 a day is a good aver-
age ; 25 feet from the top of the quarry & fault shows dip-
ping 20 to the south ; it has moved the slate on top 3 feet
to the south.f
62 Henry's quarry ; 150x200x70 ; dip 20, S. 50 E. ;
cleavage 13, S. 40 E. ; slates thin bedded ; joints vertical
and in different directions ; main joints parallel to strike ;
some few quartz veins / color of the different beds of slate
almost identical ; planes of loose cleavage from 5 to 7 to 12
feet apart ; two cable derricks, run by one engine ; make
about 1,800 squares a year.
65. St. Nicholas quarry, James Titas, township line 1
*Two miles northeast of Kessler's Post Office, thin bedded slates show
dipping 20 noith ; cleavage 40 south.
fOu M. Train's farm south of his house there is a shaft sunk for slates, 15
feet deep. The dip is doubtful but looks 50 S. Cleavage is 50. The shaft
just enters the solid slate. Just west of Jacobsburg a thin bedded slate
shows with a flat dip, and cleavage 30 south. One quarter of a mile south
of Jacobsburg the cleavage is 10 south. Where the Bushkill creek leaves
the township the thin bedded slates show with a vertical dip and flat
cleavage.
596 GEOLOGICAL SURVEY OF PENNSYLVANIA.
miles west of Cleartield ; 100x100x30 feet ; dip 15, S. 40
E. ; cleavage 55, S. 40 E. ; full of water in 1882.
66. Douglass slate quarry, on north side of Bushkill
creek, west of Douglasville ; 300x150; full of water.
69. 1 miles west of Cherry Hill in front of J. Heyer's
house two small openings 50x75 and 20x20; slates thin
bedded and on the dump have bleached and rusted badly.
A few hundred yards further down the run there is an
abandoned quarry 150x100 feet full of water ; dip 35, S.
40 E. ; cleavage 15, S. 40 E. ; slates thin bedded.
71. Daniel's quarry, full of water, 250x150 feet ; slates
thin bedded ; dip flat ; cleavage 20 S. Some of the slates
on the pile Jiave about 10 beds in them.*
Upper Nazareth township.
At the end of the borough of Nazareth the slates are flat
and rolling. One mile west of Nazareth, on the Bath road,
black slates show with a horizontal dip. A high slate ridge
rises 1,000 feet north of the road, but the slates extend half a
mile south. This is a good place to study the Utica black
slate for mat ion III a, and its passage upward into the
Hudson Ricer formation III />.
Moore township.
16. Daniel Beef s quarry, on the east side of the town-
ship, half a mile south of the railroad : 150x100; full of
water ; on the same beds as the St. Nicholas ; dip 10 S.
40 E. ; cleavage 65, S. 40 E.
*There are about 50 squares on the pile, most of them have iron pyrites
in them at the junction of the ribbons; the slates on the end of the pile
have changed color. Some of them also have thin veins of quartz in them.
On the east side of the creek 100 feet north of the Daniel's quarry, the thin
bedded slates are seen turning to the north, the dip being 20 north. The
cleavage is 20 south. 500 feet further north the dip is 20 to the east ; 50
feet further north it is 10 north. 800 feet north of this there is a small aban-
doned cut 60X60 feet showing the slates flat. Half a mile north of Daniel's
quarry a small opening 10 feet deep in thin bedded slate shows, with a dip
of 10 to the south and a cleavage of 15 south. Half a mile north of the
above there is another abandoned quarry 50x75 feet, full of water. The
slates are all thin bedded, bleached and iron stained. The dip is flat and
cleavage 20 south.
SLATE IN NORTHAMPTON AND LKHIGH COUNTIES. 597
79. Chapman quarry; 500x300x139; has 6 cable der-
ricks run by independent engines ; 30 shanties in opera-
tion ; splitters make from 2 to 6 squares a day, averaging
about 4 ; hoisting apparatus very complete ; can hoist a
stone of two tons 150' vertical and 300' horizontal'in about
2 minutes ; large factory for making and planing slabs and
other sawed material ; with 3 diamond saws, 4 planers, 1
jig saw and 1 smoothing table ; diamond saws cut by re-
ciprocating motion, at the rate of an inch in 5 minutes,
50 stroke a minute. The slates are all thin bedded, split
well and are tough ; the blocks come'out of the quarry in
large even pieces, some of them 20 feet long ; sculp and
fracture well.*
82. ^Empire quarry, on the Manocacy creek, 1 m. E. of
Chapman's; 100x100; full of water; cleavage 10 south;
slates thin bedded ; iron pyrites in some of them ; also a
few small quartz veins running through the slates.
83. Richard Moser* s quarry, 300 yards up the creek from
the Empire ; full of water ; cleavage 20 south ; slates thin
bedded ; weather to a slightly different color ; some show
iron pyrites.
84. MaucJi Chunk quarry, at Chapman's Station; 200 x
150, full of water ; dip vertical ; cleavage 22, S. 40 E. ;
slates tHin bedded.
j^
So. Bethlehem quarry \ 200x150x80; dip on the surf ace
vertical, then south a short distance and again vertical ;
cleavage 10 south ; slates all thin bedded ; distances be-
tween the loose ribbons along the cleavage of the workable
beds are 7', 7', 3', 9', 3' and 3' ; one cable derrick run by
a 15 horse-power oscillating engine ; six shanties in opera-
tion (1882). On the south side of the quarry t'ley had to
go down 60 feet before getting to good slate. On the north
they went down only 20 feet. There is a quartz vein dip-
ping to the south through the quarry 20 feet from the stir-
* A few hundred yards east of Chapman's there is an abandoned quarry
250X250. East of Chapman's, across the creek, another 50X50 full of water ;
cleavage 20 E. ; slates thin bedded.
598 GEOLOGICAL SURVEY OF PENNSYLVANIA.
face on the north side and 60 feet on the south. The slate
above the vein has not a good cleavage.*
88. Thomas Ryan's quarry, 100x50x40; slates thin
bedded ; joints vertical ; cleavage horizontal ; dip towards
the south averaging about 60. Some few slates have iron
pyrites in them.
89. Jacob Flin'rf s abandoned quarry, 1,000 feet north-
west of Ryan's quarry ; 100x40x30; dip 30, N. ; cleavage
flat. Quarry said to have been abandoned because the slates
were twisted.
90. Abandoned quarry, 1,000 feet north of Chapman's,
60x60, full of water; dip vertical; cleavage S. 10 E. ;
slates all thin bedded. 400 feet west of this another quarry
100x40 full of water, with vertical dip and cleavage of 10,
S. 20 E.
91. Abandoned quarry, 1 m. W. of Chapman's, 100x50,
full of water ; slates thin bedded.
92. Helmari's quarry, 1% miles S. W. of Chapman's ;
100x100 feet, full of water; dip 45 south ; cleavage flat ;
joints vertical ; slates thin bedded ; those on the dump
bleached and iron stained.
93. McKee's quarry, 600 feet north of Helman's ; 100 x
100, full of water ; dip 22, S. 25 E. ; cleavage 15, S. 25
E. ; joints vertical, running east and west and north and
south ; slates thin bedded, f
96. Northampton quarry, 1 m. S. W. of Chapman's ;
two, both full of water; the southern one 150x150, the
other about the same size ; separated by about 25 feet of
slate ; 15 feet from the top a heavy vein of quartz dipping
slightly to the south ; cleavage 20, S. 40 E. ; slates all
thin bedded ; those left on the dump appear very rough and
thick ; some of them have iron pyrites in them, and they
have changed color. (See page 548 above.)
* Abandoned quarry west of the last and 300 feet on the strike from it ;
200'X200' ; cleavage 10, S. 10 E. ; joint vertical. A quartz rein shows in
this quarry as in the Bethlehem. 200 feet north of this there is another
abandoned quarry 100X100 full of water.
fOn the ridge a mile east of the Emanuel church, loose thin bedded sand-
stone covers the surface of the ground. 300 yards north of Emanuel church
slate dips 90 to the north with a cleavage of 45 south.
SLATE IN NORTHAMPTON AND LEHIGH COUNTIES. 599
97. Abandoned quarry (Fig. 7), \ in. S. of Chapman's,
150x150, full of water; slates thin bedded; vertical dip.
The horizontal section in the figure shows the contortions
in the strike of the rock at the northwest corner of the
quarry.
East Allen township.
98. Chester county quarry is 200x250x130 feet deep.
The slates dip 20, S. 40 W, Cleavage horizontal. At 10
to 40 feet from the top of the cut, veins of quartz show
parallel to the bed plates. The slates are all thin bedded
and the beds differ slightly in color. Some few of the
slates have a small amount of iron pyrites in them. The
blocks coming out of the quarry are large and even in size.
Some of them are 20 feet long, 4 feet wide and 2 feet thick,
but do not seem to split well. There is a little water in the
quarry. It is worked by two cable derricks, run by one forty-
horse power engine. At the corner of the road, just north
of the quarry, there is an abandoned quarry full of water.*
100. A. Koch 1 s quarry, on Catasauqua creek, 3 miles W.
of Bath ; 200x100 ; full of water ; dip 15 to N. ; cleavage
5 to S. ; slates thin bedded ; some iron pyrites.
* The contact of slate and limestone enters the township from Upper Naz-
areth east of Bath, takes a westerly direction, crossing the railroad half a
mile south of Bath, continues on to the south-west for a mile, turns to the
south for J of a mile, then turning to the west passes through Jacksonville
and then along to the west, keeping south of the road leading west from
Jacksonville. There are three outlying patches of limestone in the north-
western part of the township shown on the map. They are probablybrought
to the surface by the anticlinal which enters the slate south-west of Bath.
Their shape cannot be accurately defined owing to the surface being covered
with loose slate. A limestone quarry, 1,000 feet west of the Chester slate
quarry. The dip of the limestone is 20 to the west. On top of the quarry
there is a body of slate which is non-conformable to the limestone. The
slate is somewhat broken and has probably fallen down on the eroded lime-
stone. One quarter of a mile S. of Koch's quarry the limestone crops out,
dip flat, with loose slate on top of it. 1,000 feet south of this more limestone
outcrops, and about 50 feet lower the slates show. There is a small cut in
the bottom of the hollow at this place, hut it is full of water, and nothing
could be seen. At the saw mill dark blue, thin-bedded limestone crops out
with a dip of 30 to the S. 30 E. There is a small amount of graphite on
the bed plates. Just south of this outcrop of limestone, gray slates show,
dipping 30 to the north, and at the road leading west from Jacksonville is
gray cement stone dipping 35 to the south.
600 GEOLOGICAL SURVEY OF PENNSYLVANIA.
Allen township.
106. Abandoned gnarry, lies a few hundred yards east of
the railroad near S. B. Hoffman's house, having about 5, 000
cubic yards taken out of it ; dip 10, S. 10 E. ; cleavage
parallel to bedding ; a few quartz veins.
107. Abandoned quarry, If miles north of Siegfried's
bridge, on the Central Railroad of New Jersey, 75x50, full
of water ; dip flat ; thin bedded slates.*
Lehigli township.
108. S. Reple 's quarry, across the road from the hotel
at Rockville, 100x200, full of water. For 500 feet north
along the foot of the hill there are several small openings
showing the slates flat and dipping 20, S. 10 E. ; cleavage
65, S. 10 E. ; main opening, slates flat ; one bed 7 feet
thick, f
111. Old Harper's now Henry's quarry, % m. S. E. of
Danielsville ; dip steep N. 45 W. ; cleavage 45, S. 10 E. ;
beds small, with small tight ribbons4
11%. J. Henry's quarry (Fig. 8), m. S. of Harper's
quarry; 200x150x30; regular synclinal axis; cleavage
at center and north side vertical, but on south side about
60 south.
113. Eagle slate quarry, F. M. Hower, i m. S. of Har-
per's ; two openings in a line 100x200x60, separated by
50 feet of rock ; dip 80, S. 10 E. ; cleavage 60, S. 10 E. ;
* South of Kreidersville the slates dip 20 S. and the cleavage 20 S. On
R. R. at N. W. corner of the township the slates have a slight dip to the south,
averaging about 5 with rolls and twists and a few small vertical faults ;
cleavage indistinct, about 40 to the south ; at center and north end of cut
slates flat with rolls and twists ; everything contorted.
f Three quarters of a mile south of Rockville outcrop of large bed of
apparently good roofing slate ; cleavage 60 south. East of Harper's grist-
mill outcrop of small slate beds; dip 20, S. 50 W. ; cleavage 60 S.
J The cleavage in this quarry is not parallel to the strike, but the strike of
the rocks is not parallel to the mountain ; if it were continued it would strike
the mountain at from a mile to two miles and a half. The slates look good,
some of them are of a different color, separated by a wavy line but no rib-
bon. 200' S. of the quarry is an old opening now being filled up.
NO. III. ROOFING SLATE BELT. 601
no large beds ; cleavage nearly parallel with bedding ;
blocks of 20 to 30 feet in length sometimes obtained. They
make about 80 squares a day and also a few school slates.
114. McChunk and National quarries, i m. E. of the
Eagle quarry and close together ; one 100 x 150, the other
250x250, both full of water. In the southern one the rocks
appear to dip 80 S., the cleavage 40 S. ; largest bed not
over 5 feet, but only 50 of the 250 feet in the quarry is ex-
posed ; slates left on the pile thick and have a poor ring.
115. Uplinqer & Griffith' 1 s quarry and Uplinger &
Henry's quarry (Fig. 9) ; two quarries 150 feet apart ; 500
feet south of the Eagle quarry is Uplinger & Harper's
quarry ; dip 80 N. ; quarry full of water. 150 feet south,
at the north end of Uplinger & Griffiths' quarry, slates lie
flat ; for 800 feet more an occasional outcrop shows a flat
dip ; at the south end of the quarry (where they were
working in 1882) a synclinal axis. None of the beds large ;
slates look good and are darker than at most of the other
quarries.
116. Continental quarry, \\ miles S. of Daniels ville ;
full of water ; 200' square ; dip 80 S. ; cleavage 45 S. ;
one bed 10 feet thick.*
118. Col. B. Mauref s slate factory is one mile north of
Poplar Grove, where they make about 2,000 school slates a
day.
119. Newcille Slate Co.' s quarry, 1 m. N. of Poplar
Grove on the south bank of Bertsch creek; 75x125x90
deep ; dip 42, S. 10 E. ; cleavage 75, S. 10 E. ; ribbons
tight ; some jet black; bottom bed 15 feet ; then 4 feet of
small beds ; one bed 15 feet thick ; 25 feet of small beds,
and on top one bed 10 feet thick.
120. New York and Pennsylvania quarry, li m. IS", of
Poplar Grove ; full of water ; reported cleavage imperfect
and slate rocky.
* An abandoned quarry, | of a mile east of Danielsville and 200 feet north
of the strike of the Continental quarry, shows a flat synclinal, with the
cleavage dipping 60 to the south.
602 GEOLOGICAL SURVEY OF PENNSYLVANIA.
121. Kestef s Meadow quarry, leased by John Pauls and
Peters; 150x100x60; 10 to 15 feet loose slate on top;
largest bed 24 feet ; blocks come out in large, even pieces ;
split well and the slate looks good. In 1882, working on
the large bed, on the south side of the synclinal axis ;
cleavage about 45 S.
122. Doddridge quarry, leased by Joseph Roberts; 500
yards north of the Kester Meadow quarry ; just (1882)
started; cut down 30 feet, showing one bed 11 feet thick,
with a few small beds on top ; dip 70, S. 10 E. ; cleavage
65, S. 10 E.
123. J. Remley 's quarry, 1 m. E. of Walnut Port, small,
15 feet deep, full of water ; dip 60, S. 10 E. j cleavage 50,
S. 10 E ; two large beds reported in this quarry, the largest
one 10 feet thick (probably 10 feet along the cleavage) ;
slates on the dump look good.
12 4. HeiribacKs quarry (Fig. 10), H m. N. E. of Wal-
nut Port, leased by Caskie & Emack. The section of the
eastern face of the quarry shown in Fig. 10, gives the struc-
ture. The quarry is 100x200x60 ; main cut originally 150 feet
deep, now partially filled by waste. It is now (1882) worked
by two tunnels, one driven east and the other west. The
main opening shows the rock about vertical, but Mr. Caskie
says that in the bottom they bent towards the north.
Joints mostly horizontal and quite persistent, but some dis-
tance apart, allowing large blocks to be taken out. In each
of the tunnels there is a joint at thereof. The largest beds
are from 10 to 15 feet thick, making a total (along the cleav-
age) of about 25 feet. The whole 150 feet of the breadth
of the quarry is used for making roofing slate. There is a
factory at the quarry for making school slate with a capac-
ity of 10,000 cases a year.
126. Owen Williams & Co.' 1 s quarry, J m. W. of Hem-
backs ; 200X100X80 ; 60 feet of slate, used for roofing and
school slates ; largest bed 8 feet thick ; other beds 6', 3' and
4'. The note (1882) adds : 100 feet west of this quarry Mr.
David Williams has opened a quarry. He has only the
NO. III. ROOFING SLATE BELT. 603
gravel stripped off, which is about 20 feet deep. The beds
he expects to strike are the same as in Owen Williams &
Co.'s quarry.
127. Williams & Jones' quarry, just west of Owen Wil-
liams' quarry; 200x100x90; dip in the bottom vertical;
at the south side near the surface a roll in the rocks ; clea-
vage 60, 15 S. E. In this quarry there is a bed of slate from
which they make slate pencils.
128. Abandoned quarry just N. of Walnut Port, 200 x
200 feet, full of water.*
135. Beach, Barge & Co.'s quarry, 1 m. below Treich-
ler's, in the hill side east of the railroad, is 50 feet deep at
its face ; dip 15, S. 10 E. ; cleavage the same ; slates thin
bedded, dark blue with a good ring.f
*On the railroad above the dam, the dip of the slates is 30, S. 10 E. ;
cleavage 60, S. 10 E. 100 feet further north the dip is 25, N. 20 W. ;
cleavage 60, S. 10 E. Just above this an anticlinal shows with aflat clea-
vage ; then 100 feet further north the slates dip vertically. A few hundred
yards south of the wagon bridge the slates dip 50 to the south. A short
distance from where the wagon road goes under the railroad a massive gray
conglomerate (dipping 30, N, 30 W.) is made up of white and black pebbles
averaging one inch in diameter ; also tine grained gray sandstones. The
junction of III and IV is not visible ; but the slates 50 feet below are seen
gradually turning into sandstone. A hundred feet N. of the road crossing
is the last place the slates are seen, 50 feet below the sandstone of IV.
Further south, 250 feet, an anticlinal in the slates appears in the side of the
road. The axis of the anticlinal is about vertical, and the cleavage is par-
allel to it Two-thirds of a mile south of Walnut Port the slates dip 75
south. There are some small beds of interbedded sandstone at the same
place.
fOn the railroad, at the township line there are three peculiar curves
showing in the slates. The cleavage is parallel to the axis of these curves.
In the first one the axis dips 5 to the south. 500 feet north and under the
above there is another flat turn with the axis horizontal, then 300 feet further
north there is a flat turn with the axis dipping 10 to the south.
604 GEOLOGICAL SURVEY OF PENNSYLVANIA.
Quarries in Lehigh county.
Washington township.
140. Abandoned quarry, 1 m. N. of Slatington 25x100,
a side hill cut 25 feet deep ; dip 25 to the north ; cleavage
60 to the south.*
146. Captain D. D. Jones' new quarry, on Welch run
k m. N. of Slatington ; (1882) ; dip 10 S. and pitch 12 W.
with cleavage vertical; big bed of slate .outcrops several
hundred feet to the east, 30' thick ; twenty feet above big
bed another 7' ; good ring, dark color, even cleavage.
14-7. Welchtown quarry, John T. Robinson & Co. ; opened
in 1844 ; two large beds, one 27 feet along the cleavage, and
another on top 18 feet, separated by 25 feet of smaller beds ;
in 1882 making 8 squares a day ; worked by a tunnel on the
27 foot bed.
llfi. Williams' railroad quarry, a few hundred yards
north of the Slatington depot, 100x100x100 feet deep.
149. Old Keystone quarry, 200' N. of the Williams RR.
quarry ; side hill cut 200 feet square, 60 to 80 feet deep
at the face ; one large bed 16 feet, then 10 feet of small
beds, then a bed underneath 25 feet ; dip 30 to the S. 10
E. cleavage vertical ; dip the same all the way to the Wil-
liams quarry ; 150 feet south of the Williams quarry slates
dip 70 south, cleavage 30 south.
150. Tunnel quarry, on Trout run, 300 yards from river ;
one large bed back of the tunnel ; two smaller cuts along
side the tunnel had fallen in.
152. Abandoned quarry, just above the borough bridge
on the south side of Trout run; side hill cut 100x50x40
feet at the face ; dip 32 S.; cleavage 64 S.; five to twenty
* At the southern end of Slatington the slates in the river are vertical.
200 yards S. of C. Zellman's on the railroad fine-grained sandstone out-
crops; dip 20 to S. ; largest layers 4 feet thick ; 40 feet of sandstone shows.
50 feet further south a synclinal shows with the sandstone on the south side
of it vertical. 300 yards N. of Rockdale slates dip 45 to the south ; cleavage
parallel. At the water station slates are flat. Just south of the run the dip
is 25 N. ; rocks slaty sandstone and slate. Then for over a quarter a mile
southward the slates are flat. They then change gradually to a dip of 25
to S. In the next 200 yards the dip changes gradually to 15, N. 45 W.,
making a synclinal axis between these two points. 500 yards further down
the railroad Ihe dip is 20, S. 45 W.
NO. III. ROOFING SLATE BELT. 605
feet of loose slate at the surface ; beds showing all under
four feet thick.
153. Penlynn quarry, 150x150x100 feet deep; dip 60,
S. 10 E; cleavage 40, 8. 10 E. There is a 20 foot bed in the
quarry. The other beds are smaller and most of them
workable. North of the quarry 100 feet dip 90; 200 feet
further north flat.
154. Old quarry No. 1, 500' N. 40 E. from the Penlynn
quarry, on the north bank of Trout run, E. of Washington
quarry ; slates vertical ; cleavage 60 south ; two 10 foot
beds with smaller beds between.
155. Old quarry No. *2 (Fig. 11), around the curve in the
hill from quarry No. 1. It shows a synclinal axis with the
plane of the axis dipping 70 to the south. The cleavage
also dips 70 to the south parallel to the plane of the axis.
It also shows tJie bed thickening as it curves around the
axis from 27 feet thick to 35 feet. Just after the curve the
distance from where it is 27 to where it is 35 feet is 50
feet*
156. Old quarry No. 3, a short distance down the creek
from No. 2 ; one bed 20 feet thick dipping 28 S. ; cleavage
75 S. The quarry not worked in 1882. All three quarries
belong to James Hess & Co.
156a. Washington quarry, James Hess & Co., 300 x
200x75 deep ; at the south side the slates, flat at the middle
of the quarry, turn sharply downwards, the dip becoming
vertical; cleavage 60 S. ; upper bed 15'; then twelve feet of
small beds ; lower bed 12'.
15Gb. Blue Vein quarry, 200 feet south of the Wash-
ington quarry; on the same beds; 200x 150x75 ; a synclinal,
its axis dipping 60 S. ; an anticlinal between this quarry
and the Washington. f Under the twelve foot bed there is
a school-slate bed. The lower four feet of the big bed has
rock in it. The ribbons when they get under thirty or
*This is a flagrant proof of the effect of the earth movement on the whole
formation No. Ill, in changing its thickness.
f This synclinal axis passes north of the t enlynu quarry through Slating-
ton, and shows in the Tunnel quarry. It does not show at the river, prob-
ably owing to a want of exposure,
606 GEOLOGICAL SURVEY OF PENNSYLVANIA.
forty feet of cover become tight. In the south wall the
slates are bent.
157. Blue Mountain quarry (Fig. 12), 600' long east to
west, 250' at its widest part, 120' deep ; surface loose for 10
to 15 feet down ; two beds 16 and 27, separated by 12 feet
of smaller beds ; started 35 to 40 years ago ; originally
worked by Williams & Moser ; 4 spar derricks and 1 large
cable derrick. They are making 55 squares a day (1882).
158. Columbia, quarry, N. side of Trout run N. of the
Blue Mountain quarry ; 300 feet long ; dip vertical ; clea-
vage 20, S. 20 E. ; 10 to 30 feet of loose rock on top.*
159. American quarry, No. 1 and 2 (Fig. 13), W. of Co-
lumbia. Quarry No. 1, 250x100 feet; beds 30', separated
by 6 feet of small beds, one being 2 feet thick. No. 2 shows
the section Fig. 13.
160. Girard quarry, m. W. of Columbia on the N. side
of Trout run ; 250x100x50 ; full of water ; one bed 15 feet
thick,
161. Star Slate quarry, 300x100x60 ; dip 70, S. 10 E.;
cleavage 50, S. 10 E. ; two beds 27' and 18' ; 10' of clay
on top, and 4' of blue slate underneath the clay.
162. Williams, Owen & Jones' quarry, 40 feet deep, 100
feet square, in line with Star quarry ; shows the slate turn-
ing over towards the south ; one derrick, working on the 27-
foot bed.
163. Franklin quarry (Fig. 14). H m. W. of Slatington
depot and N. of Trout Run. (There are several old openings
south of it towards the Star quarry.) On aflat synclinal ;
4 spar derricks and one cable derrick ; greatest deph 150'.
165. Junction quarry, opposite the junction of the Slate-
dale branch railroad, full of water, 200x100' feet square;
one bed 15' ; the rest all small ; dip steep S. ; cleavage about
50 S. 200 feet north of it a small quarry 50x50, full of
water. On the Lehigh and Berks RR. S. E. of the junc-
tion quarry aflat synclinal shows vertical cleavage.
166. Industrial slate quarry, 300 N. of the Junction
*500 feet south of the Columbia is an old abandoned quarry ; the dip of
the slate is 70, N. 20. The cleavage 50, S. 20 E. 150' S. E. of thi% the
dip is 10 N.
NO. III. ROOFING SLATE BELT. 607
qnarry ; working on the 20 foot bed ; (1882) making about
15 squares per day ; dip vertical at the surface, curving to-
wards the south at the bottom of the quarry ; cleavage
about 45, S. 10 E.
167. Abandoned quarry 1000' W. of the Industrial, full
of water, 200x290x40. There are three other openings be-
sides this, the largest 300x100, all full of water ; one large
bed 15 feet thick.
168. Abandoned quarry 1500' from the end of Slating-
ton. Its section is shown in the section of the Blue mount-
ain quarry.
169. Blue Mountain slate quarry (Fig. 15), 250' N. of
east; 200x40x60; largest bed 27' ; dip~60 N. ; cleavage
about 60 S. ; at bottom of large bed cleavage slightly
curved ; section of the two quarries shown in Fig. 15.
170. Monarch quarry, owned by Mr. Hersh, on the south
side the creek from the Blue Mountain quarry shows the
same beds with a dip of 15 N. ; not worked (1882). Across
the road another abandoned quarry ; dip 70 N. ; beds ap-
parently the same. Two other quarries in the same field,
the largest 150x150x50' deep.
171. Lock slate quarry (Fig. 16), m. W. of Slatedale.
At the southeast end of the quarry there is a small open-
ing 50x50x50 feet showing a bed 15 feet thick, dipping
85, N. 10 W., with a cleavage dipping 70, S. 10 E. The
main quarry is 400' long. In 1882 the work was under
ground by means of two slopes going down on the large
bed ; cable derricks worked by one engine ; inclines three
feet apart ; structure shown in Fig. 16.
17%. Standard quarry, i m. S. E. of Slatedale, 300x50x
114' deep ; beds 20', 8' and 16' ; 3 of gravel and 6' of loose
slate over the quarry ; the 16-foot bed worked ; a large bed
at west end did not work well ; rocks sculp and split nicely
and come out of the quarry in good sized blocks.*
*Grey slate shows in the southwest corner of the township, dipping 30,
S. 20 W. The sandstone strata seen on the railroad one mile below Slat-
ington makes a high hill which extends west more than two miles back
fronj the river. No solid outcrop shows, but the ground is covered with
loose pieces,
608 GEOLOGICAL SURVEY OF PENNSYLVANIA.
JVorfk WJiitehall township.
175. North feach Bottom Slate Co.' s quarry, 2m. S.
W. of Laury's Post Office; 250x200x90 at the deepest
place ; slate beds horizontal, with slight rolls ; cleavage
about horizontal ; joints vertical, but make different angles
with each other ; blocks 20' square got ; largest bed be-
tween loose ribbons 8' thick. About 30 feet from the sur-
face there are segregated veins of quartz that split the
cleavage for some distance around the veins. At the top
of the quarry there is a bed of sandy slate which does not
split well, bat the slates made are black, with a good ring
and smooth surface ; the second quality slates have a very
uneven surface and look poor. A factory connected with
the quarry was engaged on an order for flooring for the
Patent Office in Washington, 1882.*
Heidelburg towns/tip.
182. Diamond Slate quarry (Fig. 17), leased by Hartley
& Bar ; opened 1854 ; 250x150 ; two large beds, one 24 and
and the other 30 feet thick, separated by 5 feet of small
beds ; on top of the 24-foot bed a few quartz veins / a few
also in the slates above it ; beds rise slightly E. along the
strike. At 500' N. of the main quarry is an old abandoned
quarry ; dip 45, S. 10 E.. and nothing to be seen.t
* There are very few exposures in the township at which the dip can be
obtained. On the small creek that empties into Jordan creek in the south-
west part of the township, there are two dips to be had just east of the school
house, the slate dips 10 to the south and a quarter of a mile above the
mouth of the creek the slates are flat, with a few small rolls in them for half
a mile on each side.
f At S. end of Germanville slates dip 55 S. On Jordan creek 1 in. E.
Pleasant Corner, a sharply folded anticlinical shows dipping 60 to the
south. On the south side dip 50 S. ; north side 70 S. This shows a tight
compression and overthrow. Half a mile south slates dip 50 south. 1|
miles up a small creek that runs into the Jordan at this point, there is an
abandoned slate quarry with nothing to be seen. \\ m. E. of Pleasant Cor-
ner slates dip 30 S. 20 E.
NO. III. HOOFING SLATE BKLT. 609
South Whitehall township.
183. An abandoned slate quarry on the Huckleberrv ridge
synclinal % m. S. of Guthsville, 200x100, full of water;
slates vertical ; cleavage 45 S. ; slates all thin bedded.*
Lynn township.
192. Laurel Hill Slate Co.'s quarry, 1m. IS. E. of Lynn-
port ; 75x50x60 ; dip vertical ; cleavage steep toS. 40 E. ;
beds worked are 26', 10', 8', 6' and 2' in length along the
cleavage
193. Lynnport Slate quarry, at Lynnport, north of the
railroad, 150x100x60 feet.*
194. Two abandoned quarries at Slateville ; the one beside
the road shows the northern half of the anticlinal axis,
with one bed 4 feet thick ; the other quarry shows the slate
dipping about 45 S., with one bed 4 feet thick.
195. Star Slate quarry (Fig. 18), George W. Griesheimer
ct Bro., at New Slateville, one mile northwest of Stein-
ville ; started about 1868 ; worked by the present owners
silica 1876 ; make about 7500 squares a year. The cross
section Fig. 18 shows one large bed 30 feet thick.-
Quarries in Berks county.
Albany townshiy.
195. Centennial quarry, 1 m. W. of Steinsville, Faust,
Heinly & Bros., 150x50x80; 80, N. 20 E. The section
*Low Hill township has no quarries. At its X. E. corner slates dip 15,
S. 60 W. ; i in. further down a small run the dip is 45 N. with cleavage
45 S. curled. Just below Low Hill on the Jordan slates dip 30 S., cleav-
age curly. A few hundred yards further down the dip is 30 S. 1| m. down
the creek slates dip 50, N. 10 W., dark blue, thin bedded, with no regular
cleavage. \ mile further down the dip is 50, S. 20 E., slates massive, cleav-
age irregular. In the road across the Weidasville bend in the creek the
ground is covered with pieces of quartz. 1| miles down the creek from
Weidasville the slates are flat. Half a mile S. of Low Hollow P. O. slates dip
50, S. 10 W. ; cleavage parallel to dip. At the northwest corner of the town-
ship slates dip 80 S. One mile N. E. of Lyons Valley P. O, slates are flat.
One mile S of Claussville slates are flat ; and on the creek in the southwest
corner of the township veins of quartz show in the slate.
*1| m. E. of Lynnport slates dip 55 S.
610 GEOLOGICAL SURVEY OF PENNSYLVANIA.
M.ffA tu&eAter {flak
Phyllo^ptu. typn.. A grap.clite .gured by H.II, Pa.
NO. III. ROOFING SLATE BELT. 611
cut shows the quarry and a small opening made on the
large bed to the south.
196. An abandoned quarry, east of the Centennial, nearly
on the county line; bed 20 feet thick, dipping 70 N..
cleavage vertical.
Weisenburg town.sliip.
199. Old quarry, east of Siepstown, near the township
line ; dip 70, S. 20 E ; cleavage 20, S. 20 E., tolerably
perfect ; slates look like good roofing slates.*
Albany township.
S05. John GiW s flagstone quarry is two miles from
Kempdon station. The sandstone dips 65 south. The
strike of the rocks would carry it directly into the point of
the mountain. The sandstone conies out of the quarry
with rough faces, but after being dressed it looks good.
Just north of the quarry slates dip 35 south. f
*One mile south of this slates dip 10 N. ; and | m. further south, in upper
Macungie township, slates dip 20 to the south. H miles N. of Seiberlings.
ville an outcrop of red slate shows in the road, but it is not roofing slate-
One mile north of Seiberlingsville, along the curve of the hill, there is an
outcrop of thin bedded grey sandstone ; also some light green slate. This
outcrop shows for about a mile.
f At Trexler's station the slates dip 20, S. 20 W. | a mile west they dip 45
to the south. Just east of the Mountain Post Office the dip is 64O, s. 10 E.
| a mile west of the Post Office it is 80, S. 20 E. 1* miles west of the Post
Office the dip is 63, S. 10 E. Going on west into the cove at Digby Miller's
the dip is 80, S. 10 W. At S. Knesler's it is 52, S. 10 E. At William Bo-
lick's it is 90, S. 10 E., and, also, near the same place it is 75, S. 10 E. At
John Berg's it is 90. At this place there are thin bedded dark gray slates,
with inter-bedded sandstones. The sandstone is fine grained and in thin
layers. The outcrop shows 500 feet of slates and sandstones. At the new
Bethel church the slates are vertical. Just north of the church they dip 45
to the south;
One mile east of J. Gilt's quarry there is red slate with dip of 20, S. 10
E. The slate has patches of green in it. On the road just below the grist
mill slates and inter-bedded sandstones dip 45, S. 20 W. 200 yards south
red slates show 40 feet thick ; dip about 60, S. Opposite the school house,
light greenish sandstone makes the high ridge to the east called Round Top.
1000 feet further down red slate shows. J m. south of the grist mill thin
bedded olive slates dip 80 N. A shaft on Stone run 1| miles above its
mouth was sunk on red slate, 20 feet deep ; red slate 20 feet thick, some ol
it has spots of green in it ; also, some green slate ; no roofing slates ; cleav-
age not good, i m N. of this, a gray sandstone dips 90, S. 10 W. 5 m. N. of
612 GEOLOGICAL SURVEY OF PENNSYLVANIA.
JfiMl.
Orthis (Platystrophia) biforata, Var. dentata. Orthis dicho
/// / 3. !
g;>5-t^v.i
Orthis (PlatystropMa) biforata, Var. acutilirata. (Del
So /":m*~~Sl, XTW^ St. Orthis jamesl, Hit. If* A,* , Ui
JSNf U
LV.l
Orthi3 clytie, Hall, 14th Annual
Orthii (Platyitrophia) biforata. ( Terebra Orthis orthambonltes,
II.
cerata ' H - 13 "> * I860, p. 12, ;
00 \
Orthis emacerata. v ar. multisecta,
OrthU occidentals, Hall. Pal. N. Y. Vol. 1, 1841
fill
Orthis Insculpta, Hall, Pal. N. Y. Vol. 1, 1847.
frl
MfVMf
Orthis retro sa f Salter, (ieol. Survey of
NO. III. ROOFING SLATE BELT. 613
Wessnersville slates dip 45, S. 10 W. Half a mile south of Wessnersville
red slates dip 90 S. 2 m. S. E. of Wessnersville olive slates dip 50, S. 30
E. 1 m. W. of last is a red slate outcrop.
Greenwich township has no quarries. On the railroad \ m W. of town-
ship line, slates dip 58, S. 20 E. Opposite Lenhartsville, slates and thin
bedded sandstone dip 55, S. 20 E. At the road crossing red slates show.
On the small creek 2 in. N. E. of Lenhartsville red slates dip 55 S. 1| m.
E. of Smithsville, a fifty foot outcrop of red slate in the road. | m. N. of
Smithsville red slates crop out. 2 m. W. of Smithsville, 15 feet of red slate
dip 55, S. 20 E. At Klinesville, red slate outcrop. The hill 1 m. S. of
Klinesville is made of fine grained, thin-bedded sandstone. On the south
side of the hill red slates show in layers as far as the school house and along
the road to the east for a mile and a half, i m. S. of Smithsville slates dip
200, S. 400 W.
Half a mile further there is an outerop of massive flaggy sandstones.
There aie two small outcrops of limestone in the township ; the northern
is on S. D. Kohler's farm ; length of outcrop unknown owing to loose slate
covering it. Just north of this outcrop the slates dip 35, S. 2QO E.
The other limestone outcrop is half a mile south of W. Heffner's grist
mill ; dip 10 N. ; limestone blue and thin bedded.
Maxatawny' 'township has no quarries. 1| m. N. of Kutztown the slates are
flat : also \ a mile north of this, on top of the hill above the j unction of the
slate and limestone, the slates lie flat, but at the lower side of the same cut
dip 45 west
Richmond township has no quarries. E. of Virginsville one mile, lime-
stone outcrops ; the most northern dips 30 N. A quarter of a mile south
(with slate showing between) the limestone lies flat with rolls in it. Half a
mile south of this, with slate between, the limestone dips 30 north ; it is
dark blue, thin bedded, and shows 100 to 200 feet, and has the appearance of
the Trenton. Along the small creek half a mile east of this there is no lime-
stone to be seen ; therefore the outcrop is probably that of a sharp anticlinal.
Two and one-half miles E. of Virginsville thin bedded sandstone dip 30 S.
m. E. of Merkel's saw mill slates dip 90 W. ; also some fine grained sand-
stone. Just below Merkel's saw mill slates dip 35, S. 30 E. On the hill
north of Moselem furnace slates dip 15, S. 60 W. m. S. of Moselem
furnace slates dip 20 north. 1 m. W. of the furnace the dip is flat.
Windsor township has no quarries. At school house No. 4 slates dip 90,
S. 30 E. with some slaty sandstone. 300' S. red slate shows for half a mile
east | m. S. of St. Paul's church red slates show for GOO feet acrossthe out-
crop; no dip visible; m. E. the same dip S. 60, S. 30 E. 1^ m. E. of
Hamburg slates dip 50 south. 1 m. E. at the old railroad grading alter-
nate beds of slate and sandstone dip 52 S. 20 E. At the east end of Ham-
burg sandstone outcrops in the road. 1 m. N. of Hamburg alternate beds
of slate and sandstone dip 75, S. 10 E. waving. m. below the lock-
house sandstone dips 10 E. (massive sandstone of IV). 500' further up
the river dark gray slates dip 50, S. 20 E. 200 feet shows underneath gray
slate, slaty sandstone and thick bedded sandstones. 1 m. E. of Hamburg
slates dip 60 S. | m. further east fine grained olive sandstone, 15 feet thick,
thin bedded, dips 80, S. 10 E. South of the run red slate, 30 to 50 feet, dip
50, S. 10 E. 1 m. N. of Windsor Castle slates dip 60 south. ^ m. N. of
Windsor Castle slates dip 35 south. 1| m. E. of Windsor Castle slates dip
60 south.
614 GEOLOGICAL SURVEY OF PENNSYLVANIA
MMl.
LV/.
Crthia oinnata, HaM. Pal. N. Y. Vol. 1, 1847, Ifud. lit
un
*r*fe
rieurotomona '.Scalituf) tropldophora, "get.
Pholidop. Cincinnati
Orthodesma parallelum. ( Orikmota parallel*.
OrthodeBma corvatum, H & W 1'al. Ohio, , |tg ^^^^^^^I4
"' ! ' *fP^
m
Orthoceras capitollnum. Sfford Geol. Tenn. 1869
Sal-ford.
Orthoceras dnseri,
Gfol.Tenn.rU
NO. III. ROOFING SLATE BELT. 615
Perry township.
244- A flagstone quarry, at the northeast corner of the
township, worked by Jacob Derby. The stones make good
flagging, and are taken out generally 2' X 3' X 3" in size. Some
are 10 feet long. They are dark gray and come out regu-
larly. The sandstones roll to the north and south and dip
to the northeast.*
850. W. Collier's flagstone quarry, f m. N. E. of Shoe-
makersville, is 150 feet long. 10 feet of flagstone exposed
has from 5 to 10 feec of broken slate on top. Stones, from
2' to 4'x5' to 8', show dark gray generally, 2 inches thick,
with smooth faces. The joints are not regular, making a
loss of about one-third in squaring them up. Half a mile
southeast of this quarry the slates dip 80 south.
51. A small flagstone quarry, two miles east of Shoe-
makersville, 20x30x10 feet. The stones on the pile are
6x6x3 feet; quarry full of water. One mile south the
slates dip 50, S. 10 W.f
* Half a mile west slates dip 50 south. 500 feet south limestone outcrops ;
30 ieet; shows west for three miles. Just west of the Zion church it is flat
with rolls in it { m. N. of the church slates dip 50 south. 1000 feet south
of the limestone red slate outcrops. One mile south of the above limestone
outcrop is another about parallel to it. On Peter Folk's farm the limestone
dips under the slate at an angle of 20 to the south. At the corner of the
roads the slate dips 18, S. 70 west. 1 mile further west the limestone dips
32 U south ; light blue and broken. lj in. further west the limestone dips
20, S. 20 E. Is light blue with some siaty limestone on top. Limestone
shows again at the creek above the grist mill.
t At the north end of Mohrsville the slates are flat 1| m. N of Shoe-
makersville on the canal slates dip 45, S. 30 W. 200 feet further north,
dip 90, N. 30 E. ; probably an anticlinal brings up the limestone further
east. 1 m. further up the canal slates dip 60 S., 30 W.
In Ontelaunee township, 1 m. N. of Evansville, limestone outcrops show
100 feet wide. 1J m. E. of Leesport slates dip 55", S. 20 K. 1 m. N. of
Leesport, slates and some slaty sandstone dip 40, S. 20 E. The Crane
Iron Co. J s ore bank, 2| m. N. E. of Leesport consists of two open cuts now-
full of water. At one place could get a slate dip of 45 south. The surface
is covered with loose slate, and pieces of slate coated with hematite. From
the looks of the dump I should say that the mine had a great deal of slate
in it.
616 GEOLOGICAL SURVEY OF PENNSYLVANIA.
JotiH Aeaweejk
Copied cund reduced, to /*jroin,jiyivreA
NO. III. FOSSILS. 617
CHAPTER L.
The Fossils of No. III.
The Utica Slate (Ilia) formation is very fossiliferous
in Newfoundland, Labrador, the island of Anticosti, Can-
ada (as far west as Lake Huron, where it thins out), Ver-
mont, New York, New Jersey and middle Pennsylvania,
its characteristic fossil everywhere being a beautiful little
qnaker-like trilobitethe Triarthrus (three jointed) becMi of
Green*. On the Ohio river this fossil is abundant, asso-
ciated with Leptobolus lepis and other Utica forms, not in
black slate but in blue lime shales and marls, which are
beds of passage from the Trenton limestone beds up into
the Hudson River slates, as in Lebanon and Cumberland
counties Pennsylvania ; and also in the Western States.
None of its characteristic fossils are found in the Galena
limestone, and none of the characteristic Galena forms nre
found in the Utica. f
In Centre county, Professor Evving cites Matternville as
a good locality for seeing the sandy slates at the base of
the Hudson River formation graduating downward into
the Trenton through a series of limy layers which carry
"fossils common to the Trenton and Utica.*
* Monograph of Trilobites, 1832. Other species of this genus are T. cana-
densis, Smith; T. glaber, Billings; and T. spinosus, all in the Utica and
the last very abundant in Canada. S. A. Miller, p. 44. The figures of these
trilobites are given life-size in my Dictionary of Fossils in Pa. Report P4,
Vol. 3, 1890, pp. 1208, 1209 ; and reduced to one-half linear on plate 38, p. 526,
and plate 43, p. 536, above.
fS. A. Miller, p. 44.
JThe whole of No. Ill, Utica and Hudson River combined seems to be
only 800 feet thick. At Egg Hill in Penn's valley, and Spring Mills, tran-
sition (Utica) shaly limestones holding Trenton fossils are well seen. Me-
tween Jacksonville and Howard near the base of Bald Eagle mountain a
tough black lime shale crops out (overturned to 60) ; and near Hoy's house,
at the base of the mountain (that is, high in III) fossils are seen like those
at Egg Hill.
618 GEOLOGICAL SURVEY OF PENNSYLVANIA.
,a&ffiafy6 t 1/orJr county
NO. III. FOSSILS. 619
Prof. Ewing makes no attempt to separate the Utica from
the Hudson River, but names the following list of fossils of
No. Ill as a whole as being in his collection :
Stems of Glyptocrinus decadactylus ; Orthis lestudin-
aria; a cast of OrtTiis subquadrata(\) ; OrlJiis / Stro-
phomena alternata ; Leptcena sericea ; BelleropJiou bilo-
batus ; Murcltisoniagracilis ; Modiolopsis modiomorpha ;
Modiolopsis curta ; Ambonychiaradiata; OrtJionota, ;
Trinucleus concentricus ; Callimene ( Triarthrus) becJcii ;
Callimene ; Orthoceras .*
The Utica fossils catalogued in C. Hall's special collec-
tion for the Survey (O3, p. 190 to 192) consist of 44 indi-
viduals of Triarthrus (Calymene) beck ft, got by him at
Bellefonte, with crinoid stems, fragmental and poor ; also
47 hand specimens collected by W. A. Fellows, along the
Bellefonte outcrop, some of them slabs showing on their
surfaces numerous fragments of that trilobite, mostly heads,
comparatively few bodies, and these nearly all more or less
crushed or distorted ; tail pieces comparatively rare. Also
85 other specimens of the same trilobite.
These suffice to show the vast abundance of this charac-
teristic trilobite life in that .part of the Utica sea which
covered middle Pennsylvania. No doubt any collector
could fill his cabinet with^individual specimens at any place
along the numerous and very extensive outcrop lines.
In Bedford county, the Utica black shales, about 200'
thick, containing a few compact slate layers an inch or so
thick, show a few graptolites. They pass gradually up-
ward into brown shales, and then into non- fossil if erous
yellow shales which make up the mass of the Hudson River
formation, some thin sandstones being seen near the top.
The whole of III is only about 700' thick, f
* Report Centre county, T4, 1884, page 427. He adds that most of these
forms are found also in the Trenton limestones. So far as the fossils can
guide us in the identification of strata at a distance it would seem as if in
middle Pennsylvania only the lower half of No. Ill was deposited, the
upper or roofing slate division being wanting. Yet the distance between
Allentown and Bellefonte is only about 150 miles.
t Stevenson, T2, 1882, page 93.
620 GEOLOGICAL SURVEY OF PENNSYLVANIA.
Clisiophyllum oneidense. (Billings Canad. .
VIH a-. Cornift/reuS 7/
UngTila cuneata, Conrmd. (He. Tren/on in Pa.
NO. III. FOSSILS. 621
The Hudson River formation, Hlb, a marine deposit
from the Gulf of St. Lawrence west to the Red River of the
North, and south to Tennessee and Texas, varies in thick-
ness from 6000' on the Delaware and 2000' in eastern
Canada, to 1100' at Toronto, 250' in Missouri, and 100' in
the far northwest.
It is very fossiliferous around the Falls of the Ohio, where
it consists of 800' of blue lime shales and limestone layers.
The seas swarmed with animal life and seaweed, and many
of the strata are composed wholly of their remains.* Some
fossil forms lived through the whole age, and occur from
bottom to top : Callimene callicephala / A saphus gigas,
and megistus ; Bey rich ia chamber si ; Leptcena sericea /
Bellerophon bilobalus ; Zygospira modesta ; Stropho-
mena alternata ; and Orthis testudinaria / and all of them
(except the Beyrichid) have been found in older strata
(No. II). L. sericea continued to live into a later age.
Other forms (at least in the Cincinnati country) seem to
have had but a short range of life : Streptorhynchus hal-
lianum has a limited range in the lower part ; Streptor-
hynchus planoconnexum and sinualum are limited to
strata below the middle ; Streptorhynchus nutans and sul-
catum are confined to the middle zone of the upper division ;
Streptorhynchus subtentum and filitextum are confined to
the upper part. Of five species of Lichenocrinus three,
crater if ormis, dyer I, patter soni. are confined to the lower
half ; two, tuberculatus, affinis, to the upper part. Of
species of the trilobite Acidaspis one, crossota, occurs
below ; two. anchoralis, Cincinnati ens is, in the middle ;
one, coralli, above. RhynclioneUa capax and dentata,
Streptelasma corniculum, Favistella stellata, Tetradium
fibratum, Cypricardites, &c., are confined to the upper
*S. A. Miller's N. A. G. and P. Cincin. 1889, p. 46. He describes the out-
crop from Cincinnati west, 50 miles, to Osgood in Indiana, N. to Dayton,
and X. E. to Xenia. The hills at Cincinnati expose the lower half (400').
In Kentucky it makes a circular clay crop around the Bluegrass country.
It is rare to find a layer of solid limestone (in the 50' of clay) more than
one foot thick. The stone is a mass of more or less ground up shells, corals
and crinoids.
GEOLOGICAL SURVEY OF PENNSYLVANIA.
NO. III. FOSSILS. 623
part. Grinoids as a rule have a limited vertical range, each
species holding by its own separate horizon.
Characteristic and widely distributed species of No. Illb
are : Aulopora arachnoidea, St^matopora inflata, Ortliis
occidentalis, Or this subquadrata,0rtkisretrorsa, Pterinea
demissa, Pterinea insueta, Cyclonema bilix, and Glyplo-
crinus decadactylus .*
At Henrietta station, in Blair county, Mr. R. E. Sanders
in 1875 obtained from the Hudson River slates ten speci-
mens of brachiopods of undetermined species. (O3, p,
191.)
From the same slates, 1 miles S. \V. of the Henrietta
mine, he got Glyptocrinus decadactylus, and other crinoid
stem impressions. (O3, p. 191.)
From the same slates in Leathercracker cove, besides the
crinoids, he collected ScJiirod.us cequalis ; Triari/trus
(Calymene) beckii , a head of Dalmanites limulurus fairly
well preserved : GraptolilTius mucronatas (?) ; and poor,
faint, indistinct impressions of other graptolites. (O3, p.
192.)
A collector of Hudson River fossils in Middle^Pennsyl-
vania must devote a long time and close attention to the
business, and if successful, will find most of his specimens
injured and distorted by the excessive pressure and shear-
ing movement of bed upon bed which took place when the
anticlinal and synclinal waves were produced
Peach Bottom roofing slate fossil seaweeds are figured
on plates LXX, LXXI, on pages 616, 618, above, for com-
parison with the seaweeds figured on plate XXVI, page
502, and on plate CXI, page , Chapter LIII on the fos-
sils of Oneida and Medina, No. IV : and to illustrate what
is said on page 183, above.
*S. A. Miller's N. A. S. and P., p. 47. See also a lull synopsis anil discus-
sion of the relationship of the Cincinnati rocks to No. Ill and No. II in the
east, in Jos. F. James' paper "On the age of the Point Pleasant, Ohio, beds,"
in Journ. Cincin. Soc. Nat. Hist, July, 1891 ; in which the conclusion is
arrived at that no beds as low as Trenton appear on the Ohio river within
the limits of the State of Ohio.
624 GEOLOGICAL SURVEY OF PENNSYLVANIA.
I
it i
NO. IV. ONEIDA AND MEDINA. 625
CHAPTER LI.
Formation No. 1 V. Oneida and Medina.
Middle Pennsylvania west of the Susquehanna river is a
labyrinth of parallel mountains, with straight sloping sides
and sharp horizontal crests, none of them elevated more
than a thousand feet above the valleys which they include.
These mountains interlock in zigzags, sending out spurs
and knobs into the large valleys, and enclosing longer or
shorter narrow parallel coves. (See pi. 73, 74, &c.)
With three exceptions, to be noted directly, all these
mountains are composed of Formation No. IV, subdivided
into three sets of sandstone and sandy shale beds; the
lowest one (IV a) known as the Oneida conglomerate; the
middle set (IV b) known as the Medina red sandstone;
and the upper (IV c) as the Medina white sandstone.
The Oneida conglomerate (IV a) was so named by the
geologists of New York because of its coarseness, being a
pudding stone or pebble rock ; but in middle Pennsylvania
its beds are mostly a gray sandstone interleaved with a few
beds of conglomerate. Professor Rogers therefore called
it the Levant gray sandstone, because the aspest of the rock
is that of ordinary sandstone. The Medina or Levant red
sandstone (IV b} contains so many interstratified softer
shaly beds, and is so charged with iron, turning red when
exposed to the air, that it makes a. visible division between
the lower and upper parts of the whole formation. The
uppermost subdivision, the Medina or Levant white sand-
stone (IV c] is not only characterized by its purer color, or
rather absence of all color, but by its greater massiveness,
so that it constitutes the real backbone of the mountains,
cropping out along their crests.
Formation IV has been a boon to Appalachian geolo-
gists. It gave them at the very outset, fifty years ago, a key
40
GEOLOGICAL SUEVEY OF PENNSYLVANIA.
BALD EACLE CAP AT BELLEFONTE
contours of 100 feel.
%y %.H Sanders.
NO. IV. ONEIDA AND MEDINA. 627
to the structural geology of the whole region from Tennes-
see to New York. It marks the maps of Pennsy vania, Mary-
land, Virginia and Tennessee with topographical lines not
to be overlooked or misunderstood. It furnished a safe
basis for that enthusiastic investigation which resulted long
ago in the establishment of the science of geological topo-
graphy or Topographical Geology. By means of these
numerous bold mountain outcrops the plication of the
earth-crust along the Appalachian belt was at once com-
prehended and could be estimated at its full value ; could
be measured, sectioned, mapped, and modelled in solid form ;
and a number of such models have been made by the Penn-
sylvania Geological Survey. In the latest of these models
the formations which cover No. IV have been lifted off,
and the great arches in the air (long since destroyed and
carried into the Atlantic) have been restored ; so that the
complicated structure of the region is now as well known
as the internal anatomy of the human body. And this is
due, chiefly, to the great thickness of Formation No. IV,
and to the extensive outspread of its sandy sediments over
the bed of the Appalachian sea.
For a description of this model, and two photographs of
its surface, see the close of Chapter LIT.
I will first consider the thickness of the formation ; sec-
ondly the variations which obtain in its internal constitu-
tion in different parts of its outspread ; and, thirdly, the
effect which these variations have had in producing differ-
ent topographical "aspects of the country, and the lessons
which they teach respecting the formation of mountains
in other parts of the world.
The thickness of No. IV.
First : As to the thickness of the formation as a whole ;
and then, as to the variation in thickness of its subdi-
visions.
In measuring the thickness of any of our greater forma-
tions there is almost always some uncertainty as to where
the measurement at the bottom is to begin, and as to where
628
GEOLOGICAL SURVEY OF PENNSYLVANIA.
thro
ug
THE THICKNESS OF NO. VII. 629
the measurement is to end at the top ; for, as I have already
sufficiently set forth, there never has been stop or pause in
the tribute of the rivers to the sea ; and there never has been
uniformity in the nature of that tribute ; sand being de-
posited in one place at the same time that mud was being
deposited in another ; and innumerable alterations of sand
and mud of every possible variety have taken place through
the entire process. The bottom of a formation in one place
may not exactly correspond to its bottom in another place ;
and the same is true of its top. Nature has never written
its historical memoir of geological operations in distinct
and well-rounded sentences; has never numbered and
headed its chapters ; has seldom drawn strong black lines
between its paragraphs. The formations grade and fade
away into each other ; and that, both downward and up-
ward ; and the geologist who attempts to measure any for-
mation at any place must simply do his best to select some
bottom rock to begin it with and some top rock to end it
with. But in doing this he is always liable to mistake.
He must make his selections on his own responsibility. He
can never confidently assert that the bottom and the top
of his formations are established facts of science. When
he multiplies his measurements of a formation in various
places in order to obtain by comparison a knowledge of its
variations in thickness he subjects himself to the risk of
multiplying his errors. Sometimes, indeed, a special bed
at the bottom or at the top of a formation is so flagrantly
different in constitution, in color, or in its fossil forms,
from all the other beds near it, that he can adopt it as a
key rock with considerable confidence. But this is rarely
the case ; and even when such a key rock presents itself in
one part of his district, and another such key rock almost
or exactly like it presents itself in another part of his dis-
trict, there is always a possibility that the two are not con-
tinuous ; that they were not deposited at exactly the same
time throughout the region ; and that perhaps nature has
repeated the deposit locally and subsequently.
In measuring No. IV therefore we have been obliged to
assume as its bottom limit the first massive sandstone to be
630 GEOLOGICAL SURVEY OF PENNSYLVANIA.
THE THICKNESS OF NO. VII. 631
seen lying regularly upon the upper or roofing slate division
of Formation No. Ill ; and we have been obliged in like
manner to assume as the upper limit or top of No. IV, the
highest massive white sandstone bed which presents itself
at any given locality overlaid by the softer although still
sandy reddish shale beds of No. Y hereafter to be de-
scribed. Very exact instrumental measurements of No. IV
have been made in accordance with this plan, that is, be-
tween such assumed bottom and top limits, in many parts
of Pennsylvania : at the Delaware, Lehigh and Schuylkill
Water Gaps ; at the Susquehanna gap above Harrisburg;
at Logan gap near Lewistown; at Rockhill gap near Orbi-
sonia ; at the Bald Eagle gaps near Bel lefonte and Tyrone
City ; and at the gaps near Bedford. But as these meas-
urements were made by different assistants of the Geolog-
ical Corps they can be compared together only by making
allowance for the inevitable differences of personal opinion
respecting the best top and bottom limits of the formation.
Yet, after all, these differences are so moderate as not to
vitiate the conclusions drawn from the comparison ; and we
have moreover on record for comparison the equally intel-
ligent and conscientious measurements of the assistants of
the First Geological Survey under Professor Rogers, which
serve in a measure to check, and in fact help to verify their
accuracy.
The measurement of No. IV by Mr. Sanders in Blair
county sums up 2896' ; that of Mr. Dewees at Logan gap
in Mifflin county, 2722' ; that of Mr. Billin in the south of
Centre county, 2440'; that of Dr. Chance in Clinton county,
2301' ; that of Professor White at Spruce Creek tunnel in
Huntingdon county, 2000' (made uncertain by a fault); that
of Mr. Ashburner in southern Huntingdon county, 1808' ;
that of Professor Stevenson, in Yellow creek gap, Bedford
county, 2035' (diminishing toward the Maryland line to less
than 1000'); and in Fulton county about 1600'; (according
to Professor Rogers' estimate in Cove mountain 2100', and
in Tussey mountain 1650'). In the Lycoming county gaps
Mr. F. Platt estimates it at 1375'. Dr. Chance's measure-
ment at the Schuylkill Water Gap was 1400' ; at the Lehigh
682 GEOLOGICAL SURVEY OF PENNSYLVANIA.
/LXXV//
THE THICKNESS OF NO. VII. 633
Water Gap (complicated with a fault) 1125' ; and at the
Delaware Water Gap 1565'.
It will be seen by the above statement that the greatest
observed thickness of No. IV is in the center of the State,
and that it evidently diminishes in all directions from that
central district. When followed southward through Vir-
ginia it thins, at first gradually, and then rapidly, to such
an extent that the whole formation appears to be only about
40' thick at its outcrop west of Knoxville, in Tennessee.*
Westward, under western Pennsylvania and Ohio, it has
not been reached by the deepest borings ; but that it dimin-
ishes in that direction also, is evident from the fact that its
outcrop is too small to be recognized in the Columbus and
Cincinnati region. Under northern Pennsylvania and cen-
tral New York it is also completely concealed ; but it must
diminish in that direction also, for its outcrop along the
Mohawk valley amounts to only 400', diminishing toward
Albany ; and it makes no appearance at all around the
eastern foot of the Catskill mountains. This is a remarka-
ble phenomenon not to be easily explained. To most geo-
logical minds it will seem'quite sufficient to say, that dry
land existed there while two or three thousand feet of sand
and gravel were being floated into a deep sea in middle
Pennsylvania. The difficulty of this explanation is in-
creased when one follows the lofty crest of the Kittatinny
mountain along the north line of Berks, Lehigh and North-
ampton counties in Pennsylvania, crosses the Delaware at
the Water Gap into New Jersey, and follows the equally
high crest of the Schawngunk mountain into New York, to
see it suddenly cut off a few miles east of the hotels at Lake
Mahunk, to appear no more until the western border of
New England is reached. Now, when 'a mountain ridge,
the bold outcrop of a great sandstone formation 500 miles
long suddenly terminates, not as an anticlinal nose descend-
ing underground, not as a cynclinal knob rising into the
air, but as if the end of a slanting board had been sawn off,
*In the White Oak mountains of East Tennessee, however, it measures
between 800 and 900'.
634 GEOLOGICAL SURVEY OF PENNSYLVANIA.
THE THICKNESS OF NO. VII. 635
the structural geologist cannot do.ubt that the formation
has been swallowed by a fault.*
*Dr. Mather, Geologist of the First District of the New York Survey, in
his quarto report of 1843, pages 355 to 361, describes this shattered condition
of the mountain. He says that the Indians called the mountain Swang-
gum, that is "white rock." The sandstone mass he called "Schwangunk
Grit," and gives its thickness as variable between a maximum of 500 feet
and a minimum of 60, "its usual thickness being between 60 and 150." It
is traversed by two systems of faults, one parallel to the strike (N. 20, E. ),
and the other transverse (N. 60 W.). The cross faults are lew between the
Delaware river at Carpenter's Point (Port Jervis) and Ellen ville and Wa-
warsing in Ulster county, where the mountain is traversed by great breaks
and faults. "The ridge then sinks and rapidly disappears beneath the val-
ley, while several wrinkles or parallel axes of elevation spring up on the
east at the same height, run eastward between the Stony Kill, Mule Kill,
Sanders' Kill, etc.; sink down gradually towards the mouths of these
streams, and finally disappear below the valley in Rochester and Marble-
town, or show their continuation only by low broken ridges of upheaved lime-
stone. These axes of elevation are terminated apparently on the south by
the high cliffs along the transverse lines of fault. On the cast of these minor
axes the main axis of elevation takes its rise from High Point, which is a
high cliff of grit rock on the main fault, and ranges thence northeastward,
more or less broken and dislocated by minor transverse and oblique faults,
and diminishing in height until the Shawangunk mountain and its grits,
which envelope most of its higher parts, entirely disappear below the lime-
stone and quarternary deposits at and near Rosendale. Several high points
with mural fronts and ends are seen between High Point and Springtown,
as Sam's Point, Great Mogunk, Puntico Point, etc., all of which are caused by
faults along the main features of the mountain. It has been mentioned that
the wrinkles or subordinate axes of elevation seem to terminate at these
rocky points on S. E. side of the mountain, but the termination is only ap-
parent, caused by transverse fractures. The ridges almost all slope down
to the N. and N. E. from where the main fractures cross each other, and the
rocks disappear below the more recent formations, while their southward
extremities almost always present high precipitious and often vertical cliffs.."
Although these statements of Mather are not A'ery lucid, they are substan-
tially correct, as any geologist may observe who makes one of the great sum-
mer hotels, the Mohunk or the Manawaska, his headquarters. Overlooking
lakes which lift on top of the mountain, surrounded by vertical cliffs of
sandstone and conglomerate, and dammed by glacial moraines, these com-
fortable and hospitable places furnish unrivaled iacilities for exploring one
of the most interesting and instructive fields of geological research in Amer-
ica. Mather's illustrations of the Shangunk grit and its fractures on plates
V, f. 13 ; VI, f. 7 ; VIII, f. 2, 3, 4 ; VIII, f. 4 ; XV, f. 3 ; XXVI, f. 4, 5, 6, 7,
and XXXIX, f. 1, 2, 3, are so bad as to serve no purpose but that of contrast-
ing the slovenly and absurd drawings of his day with the precise and math-
ematical sections of our own. Yet even then the best geologists like Hall,
Logan, Lyell and Murchison illustrated their lucid English text with wood
cuts hardly since surpassed for correctness and beauty.
636 GEOLOGICAL SURVEY OF PENNSYLVANIA.
LXX/X.
AT THE GAP ABOVE HARRISBURG. 637
At the Gap above Harrisburg.
From the list of localities above mentioned where For-
mation No. IV has been measured to obtain its total thick-
ness, one locality has been omitted because it requires a
separate and special consideration, namely, the gap of the
Susquehanna above Harrisburg. Three separate measure-
ments have been made in this gap by Professor Rogers by
Mr. Sanders, and by Professor Claypole, without, however,
reaching absolutely sure results, owing to the overturned
and somewhat crushed condition of the formation. Every-
where else along the line of the Kittatinny, Blue or North
mountain, from the Delaware to the Potomac, the beds of
No. IV slope northward and westward at various angles
from 20 up to 80 and even 90. But where the Susque-
hanna breaks through, the earth movement from the south
has done more than press up the beds into vertical attitudes ;
it has pushed them over 20 beyond the vertical, overturning
them to a south dip of about 70. It will be shown in the
next chapter that this overturn or inversion affects not only
Formation No. IV, but all the overlying formations up to
No. XI ; and that the squeeze produced by folding 20,000'
of rock into a sharp synclinal basin has resulted in a large
amount of sliding and slipping of one group of beds upon
another, in the production of minor irregularities of dip
and strike, occasional rolls, small faults, etc., and perhaps
in the lessening of their original thickness. How much
No. IV has suffered in this respect is uncertain ; but it is
evident that under such circumstances the measured thick-
ness of any formation, whether hard or soft, cannot be im-
plicitly accepted as the real or original thickness. At all
events it would be unsafe to draw the same conclusions
from measurements made at such a place that we can safely
draw from measurements made of it at places where no
such violent upturning and overturning has occurred.
The measurement of No. IV in the Susquehanna gap
sums up less than 500'. This is at the southeast corner of
Perry county ; but in the western and northern parts of
that same county No. IV appears to be about 2000' thick.
638
GEOLOGICAL SURVEY OF PENNSYLVANIA.
AT THE GAP ABOVE HARRISBURG. 639
Following the mountain only a few miles eastward from the
Snsquehanna, to where the beds of No. IV lean in their
natural attitude (dipping north) the formation becomes of
its usual thickness ; and following the mountain westward
from the Susquehanna not more than 15 miles, the usual
thickness of the formation is again resumed. We have,
therefore, some right to ascribe its abnormal thickness at
the Susquehanna to the overturn. Another explanation
tyowever has been suggested and will be described in the
next chapters, since it affects still more seriously Formations
No. V and No. VI in this locality.
The thickness of Formation No. IV as a whole is of
course the sum of the thickness of its three subdivisions,
(lower, middle and upper) Oneida, Medina red, and Medina
white. If the relative thickness of these divisions remained
constant, and if the_hardness and softness of the beds of
the three divisions were everywhere the same, it is evident
that the shape of a mountain of No. IV would be always
the same. But the law of universal geological irregularity
operates upon all three subdivisions. In fact each sub-
division of No. IV has as much right to be considered an
individual r and distinct formation as if it had no topo-
graphical relationship with the other two ; and the only
reason why the three subdivisions of No. IV have been
grouped together into one formation is the fact that the
three together always make one mountain ; the shape of
which, however, necessarily varies with the Variations in
solidity and thickness of the subdivisions, as will be shown
directly. For the present we will regard simply the thick-
ness of the subdivisions; repeating, however, and insist-
ing still more earnestly upon it, what has already been said
respecting the indefiniteness of the bottom and top limits
of all formations and groups of beds. If the three sub-
divisions of No. IV had been made by a stone cutter out
of three slabs of rock placed one upon another there would
be no uncertainty as to their thickness ; but seeing that
they are three artificial groupings of an immense number
of sand and mud deposits, each varying in its individual
character and thickness, white and gray sandstones alter-
640 GEOLOGICAL SURVEY OF PENNSYLVANIA.
LXXX/
THE THICKNESS OF NO. IV. 641
nating with gray and reddish muds, it is extremely diffi-
cult to decide upon any fixed planes of division between
them. All that we can do is to group the lower gray sands
togther as the Oneida, the upper white sands together as
Medina white, and call the softer and more or less reddish
beds between them as the middle division, or Medina red;
and arrange their thicknesses at the various places where
they have been measured in a table like the following :
At the Delaware Water Gap. H. M. Chance /*
Medina upper sandstone, 200'
" upper shales, etc., 530, .
" white conglomerate, 200'
" lower shales, etc., 110'
Oneida gray sandstone, 75' "j roe
" lower shales, etc., 240' ^
" white conglomerate, 210' J 1565'
At the Lehigh Water Gap. H. M. Chance :f
Medina upper sandstone, 85' \
" upper shale, 180' I
" gray sandstone, 70' f
" lower shale, 330' J
Oneida cong. sandstone, 290' ) 460'
" conglomerate, 170' i . ,
* H. D. Rogers gives different measurements of No. IV at the three water
gaps, in Geol. of Pa., 1858, Vol. I, p. 126 to 130.
At the Delaware : Levant White sandstone (some sparsely pebbly beds)
making a prominent rib of the mountain, 200', (overlying sandstone and
slate alternations, may be added, or may be thrown into the formation V.)
2. Levant Red, wanting. 3. Levant Gray (Oneida) , upper division thin
bedded, soft sandstones, 400' ; lower pebbly member, 300'. Total, 900', in-
stead of Dr. Chance's 1565, the latter being the result of instrumental meas-
urements of subdivisions.
|H. D. Rogers, at the Lehigh: 1. Levant White; top division, massive
grey and red sandstone with shale partings, 100' ; shales and flags, 300' ;
sandy shales, 30' ; sandstones and shales, with fucoidal mar kings, 50' ; sand-
stones and shales, 100' ; white and gray pebble rock, 80' ; concealed (sand-
stone and shale) beds, 200' ; total 760'. 2. Levant Red, wanting. 3. Levant
Gray (Oneida) fine sandstone, small conglomerate and shale, 200' ; coarse
pebble rock and sandstone, 75' ; fine sandstone and coarse conglomerate, 75 ;
very coarse pebble rock at bottom, 50' ; total, 400'. Total thickness of IV,
1160', agreeing remarkably with Dr. Chance's instrumental measure above,
1125'.
41
642 GEOLOGICAL SURVEY OF PENNSYLVANIA.
THE THICKNESS OF NO. IV. 643
At the Schuylkill Water Gap. H. M. Chance ;*
Medina upper sandstone, 90' "j
" upper iron shales, 480' I
" white sandstone, 60' j 1230/
" lower iron shales, 600' J
Oneida white conglomerate, 200
1430'
At the Susquehanna Gap. H. D. Rogers. f
Medina upper, 300' to 400' \
" lower (red), 0' J> max. 470'
Oneida, 60' to 70' J
In the Juniata gaps of Perry county. E. W. Claypole :
Medina sandstone and shales 1500' ) 2000*
Oneida conglomerate and sandstone, 500' >
* Rogers gives no measurements at the Schuylkill and Swatara Water
Gaps.
The bottom coarse red pebble rock of the Oneida, only 5' thick, with
white coarse sandstone, full of fault slips which suggest a greater thickness
than 40', is separated from the visible upper limit of No. Ill slate by a con-
cealed interval of 50' more or less. Prof. Claypole in his report on Perry
Co., F2, 1885, p. 310, describing Rye township, makes the Medina rock rib of
the mountain to be only 100' thick, and says nothing about the Oneida. He
places 500' of " soft material" between the top of the Medina and the bot-
tom of the Clinton Iron Sandstone rib which makes the other crest of the
North mountain at Sterrett's gap, the Medina crest being the lower of the
two and in Cumberland county. In Carroll township, he says, the Medina
makes little or no show, running along south of the county line on the
crest (F2, 159). The same in Spring township (p. 333). Tyrone township,
next west, gives vertical Medina at McClure'sgap (p. 370). I have expressed
my belief and the reasons on which it is based, that this excessive thinness
of No. IV and the total disappearance of one or two thousand feet of over-
lying measures in Perry county, west (and east) of the Susquehanna Water
Gap, described by Prof. Claypole in F2, p. 303 (see illustration p. 304), and
assumed by him as good evidence of the existence of a district of dry land
in Upper Silurian times in that district of the State, is rather to be explained
by the upturned and overturned condition of the south side of the Cove
synclinal and Dauphin county coal basin, producing not only the oblique
fissuring of the Oneida outcrop in the Gap, but, as I believe, great slip-faults
paralled with the strike, swallowing up and pressing underground the softer
formations. I do not believe that No. IV was originally any thinner at the
Susquehanna than at the Schuylkill or Delaware, or than it seems to be in the
gaps of the Juniata river, even in Perry county, where in the Tuscarora
mountain, etc. Prof. Claypole gives it a total thickness of 2000' (F2,
page 36).
644 GEOLOGICAL SURVEY OF PENNSYLVANIA.
THE THICKNESS OF NO. IV. 645
Logan's gap, Mifflin county. C. A. Ashburner:
Medina white sandstone, 820' ) 21(xy
Medina red sandstone, 1280' $
Oneida red conglomerate, . 300' ) 622 , j 2722 '*
Oneida gray sandstone, 313' >
Jack's Narrows, Mifflin county. H. D. Rogers:
Levant top red sandstone,! 30' ) 45)) , 1
Levant upper white sandstone, 420' ) [
Levant red sandstone and shale, 650' '
Levant lower white sandstone , 250'
Rockhill gap, Orbisonia, Huntington county. Ashburner :
Medina white sandstone, 400' ) JOQ/W
Medina red sandstone, 930' J
Oneida red conglomerate, 158' ) ,-gg,
Oneida gray sandstone, 410' 3
Canoe Mt. gap, Huntingdon Co. H. D. Rogers :
Levant (upper) Avhite sandstone, 550' "l
Levant (middle) red beds,|| 1050 i 2100'
Levant (lower) gray sandstone, T 500' J
Bald Eagle Mt. gaps in Blair Co. R. H. Sanders :
Medina white sandstone (north crest), 1068'
Medina red alternations,** 520'
Oneida gray sandstone (south brow), 1319'
* Rogers does not measure the Upper division of IV here (Geo. Pa. I, p.
130), but subdivides the Middle division into (at top) dark red flags with
some red shale pebbles, 500' ; coarse friable red sandstones, iron-specked,
100' ; pink sandstones with layers of quartz, slate and other older pebbles,
400' ; total 1000'. The lowest ( Oneida) division, fine massive gray sandstone,
iron-specked, he makes 300'. Total only 1300'.
fSome of the layers are covered with a net-work of the sea weed,
Arthrophycus harlani.
J These and other asigned thicknesses given by Rogers in his Geo. Pa.
1858, have been proved incorrect by the close instrumental field work of Bil-
lin and Ashburner, Sanders and Chance since 1874.
" Measured with precision." Ponderous, homogeneous, fine grained
white and gray sandstone beds." Geo. Pa. I, 130.
|| " Reddish brown, rather argillaceous, with beds of gray sandstone, all
alternating with much red shale," p. 129.
1 " Wears its usual character of grey-greenish and pinkish hard siliceous
massive sandstone beds, p. 127.
**The detailed section of these alternations will be found in Report T,
on Blair county, by Franklin Platt, 1881, p. 17, discussed on p. 47. The de-
scription is minute and very interesting. The division made in the text is
liable to a great modification, inasmuch as the north crest of the Bald Eagle
646 GEOLOGICAL SURVEY OF PENNSYLVANIA.
THE THICKNESS OF NO. IV. 647
Bald Eagle, Bellefonte gap. H. D. Rogers :
Levant white sandstone, 400' to 500'
Levant red sandstone and shale,* about 500' I, 1550'
Levant upper green sandstone,! 380' > 55() ,
Levant lower gray sandstone,} 170' )
Bald Eagle, Mill Hall gap. H. M. Chance :
Medina upper (north crest), 695'
Medina middle (vale), 705' < 2301'
Oneida (southern crest), 901'
is really made by 100' of white sandrocks at the top of the section, sup-
ported by 255' of red sandstone beds parted by layers of red slate from 6 inches
to 5 feet thick. Underneath this 355' the rocks are concealed for 540', and
the detailed alternations begin and go down for 1000', leaving the bottom
division to be 1309' thick. In fact only 400 or 500' of the upper division of
1068' answer to the description of the White (upper) Medina; the Red
(middle) Medina is really 500+520=1020' thick. All this is merely a matter
of classification and does not at all invalidate the correctness of the detailed
section. The Medina White is made up of hard white and greenish gray
flinty sandstones, fine grained, compact, homogenous, with almost none of
the pebbles which make it so coarse a pebble rock in the North, Blue or
Kittatinny mountain outcrop. Its top beds are thin, mottled red and grey,
and often covered with sea weed impressions. They are parted by or alter-
nate with soft greenish non-fossiliferous shales. They are much specked
with yellow pits of decomposed iron. The Medina red upper member is
made up of red clay flagstones, with (toward the bottom) some other layers
of small quartz pebbles, flattish fragments of red shale occur throughout
the pile of sandstone beds. Such is its general character in Mifflin county.
The Oneida in Mifflin county has pebbles of quartz and slate and sandstone
apparently derived from some antient land or coast of No. Ill and No. I.
But in Blair county the Oneida shows obscure vertical plant stems. Steven-
son does not recognize the Oneida in Bedford county. The Oneida is char-
acteristically speckled and pitted by the decomposition of minute granules
of some iron ore, perhaps pyrites. Its upper subdivision is a clayey sand,
greenish gray, slightly micaceous, ochre-pitted, and its rock beds parted by
thin fissile yellow shales. The lower is an ochre-pitted hard gray sand-
stone! (T, 48. )
*Thin grey and red clay sandstone layers, alternating with a fourth part
red, grey and greenish shale partings. High in the division are found ver-
tical plant stems like Hall's Scolithus verticalis at Medina, N. Y.
t Greenish grey slightly micaceous, specked with ochre, with thin fissile
greenish slate partings. In Pleasant Gap, Center county, it is quarried for
flagstones. (T4, 428. )
t Hard gray sandstone without pebbles, but full of yellow specks.
See detailed section in Report G4 on Clinton county, 1880, p. 120. The
subdivisions are empirical. The upper hard, massive, red, grey and white
sandstones are not well exposed. The middle softer sands and shales make
the little trench between the crests. Then come hard, massive, white (with
a few speckled) sandstones, 188' : concealed, 118' ; hard, massive, siliceous
dark grey and greenish grey speckled beds, 155' ; and at the bottom a mass
not well exhibited, but principally hard massive sand rocks, 410'.
648 GEOLOGICAL SURVEY OF PENNSYLVANIA.
THE THICKNESS OF NO. IV. 649
Bald Eagle gaps in Lycoming county. F. Platt :*
Medina upper hard sandstone, 100' "|
Medina middle red beds, 1200' i> 1375'
Oneida hard sandstone, 75' j
Wills' Mt. gap, Milligan's cove. H. D. Kogers.
Levant white sandstone, 400' ]
Levant red sandstone,! 800' 1 1300'
Levant grey sandstone, 100' j
No. IV thins southward into Virginia and Tennessee.
On the James river the whole Medina measures only 300'
and whole Oneida only 90' ; together 390'4
Stevenson calls the Medina in Waldron's ridge, Lee Co.
Va., " evidently more than 300'."
West of Knoxville, in Tennessee, I saw it represented by
only 40' of sandstone.
Towards the west it entirely disappears from the Ohio
and Kentucky column.
Northward it thins away in an equally remarkable man-
ner. At Niagara the Medina is 300' or 400' ; and the Oneida,
in Oneida county, N. Y., only 100' to 120'.
But going eastward along its northern outcrop it increases.
Prof. Prosser's general section of Western Middle New
York State gives Red Medina sandstones and shales, 942'. |
* Mr. Platt says in Report G2, p. 29, that no exact measurements were made
for want of satisfactory exposures, and that the figures given above are only
probable.
t Includes here a larger amount of grey sandstone than on the Juniata.
Rogers says that in this main gap through Wills' mountain into the cove the
Oueida is last seen going south. He suspects a fault swallowing up a part
of the formation, "a conjecture suggested by the vertical and shattered con-
dition of the strata in Buffalo ridge the western barrier of the cove." Geo.
Pa. 1858, p. 128.
JJ. L. Campbell, Geol. Rich Patch in "Virginias," Vol. I, No. 12, Dec.,
1880, illustrated with sections.
Proceed. Am. Philos. Soc. Phila., Aug., 1880.
|| "Thickness of Devonian and Silurian Rocks, etc." Amer. Geologist,
Oct., 1890, p. 205. His section is made up from well-borings. Under his
Medina the Oswego sandstone, 210', is placed in No. III. In the Walcott well
on Lake Ontario, red shale and red siliceous sandstones alternating, meas-
ure 690' ; but they may be Clinton ; under them Oswego sandstone, 210'.
In the Clyde well, Wayne Co., N. Y., Medina red shales, etc., 24', 3', 915=
942'. At the bottom of the Seneca Falls well, Medina red shales and sand-
stones, 150' ; how much more unknown. At Rochester Logan made the Me-
dina 600'. Geo. Sur. Canada, 1863, p. 310.
650 GEOLOGICAL SURVEY OF PENNSYLVANIA.
NO IV. AT LOGAN GAP. 651
No. IV at Logan Gap. PL LXXXI, p. 64.0.
The best place perhaps for studying No. IV is at the
Gap through Jack's mountain in Mifflin county.
Here the white Medina sandstone beds measure 820' ;
most of them consisting of massive lawers of exceedingly
hard rock varying from 2' to 4' in thickness ; some of them
fine grained ; some of them slightly argillaceous, that is
the grains of sand are imbedded in a matrix of clay. They
slope up from the floor of the gap at the south end and
make the upper part of the mountain and its high, bold
rock-covered crest, running eastward toward the Susque-
hanna, and westward toward the Juniata ; and it is the great
thickness of these Medina while sand rock beds that makes
Jack's mountain one of the highest in middle Pennsylvania.
The weather acting upon the slight cement, dissolves it,
and sets free the sharp grains of sand, producing along the
top of the mountain collections of glass sand. Some of
the more solid beds, resisting dissolution, break up into
great blocks which slide down and cover the upper part of
the northern slope.
The Medina red middle division of No. IV in the heart
of the gap is 1280' thick. It consists of laminated reddish
sandstone layers, too soft and friable for building purposes,
interstratin'ed with red sandy shales. On the surface of
these shales ripple marks and the impressions of sun cracks
like those seen on a modern sea shore abound, leading one
to suspect that the waters of that ancient time were shal-
low, and the sea bed in places exposed to the air and sun.
But at the same time, many of the strata are obliquely
cross-bedded, as if deposited in swiftly flowing currents.
Beneath these lie the Oneida rocks, divided into an upper
and a lower group, called the Oneida red conglomerate and
the Oneida gray sandstone.
The upper group consists of massive sandstone strata,
reddish in color, very coarse, full of small pebbles which
in some places become as large as hens' eggs ; the layers
varying from V to 6' in thickness, so that large stones are
quarried from them in the gap. This mass of pebble rock
652
GEOLOGICAL SURVEY OF PENNSYLVANIA.
NO. IV. AT ORBISONIA. 653
rising at an angle of 55 to the brow of the famous terrace
which surrounds Kishacoquillis valley is 310' thick.
The lower group measures also 310', and is made up of
very hard greenish gray sandstone, the grains of sand coarse
and strongly cemented together, mixed with pebbles of
quartz, none of them as large as those in the group above.
Some of the beds are five grained, equally hard and massive,
and contain small scattered pebbles. Some of the beds
show a good deal of disseminated oxide of iron.*
About 25 miles west of Logan Gap the Juniata breaks
through the mountain at Jack's Narrows.
Here the Medina white sandstone is only 450' thick, the
30' of beds at the top being a group of alternating red, pink
and gray sandstone layers and red and green shales ; some
of the sandstone layers being covered with a net-work of
sea weed markings (ArtTirophycus Jiarlani). The remain-
ing 420' consists of strata, massive and compact, of white
and greenish gray sandstone, with scarcely a trace of any
organic life. Under these lie 650' of soft clay sandstone
generally red, and speckled yellow with iron, current bedded
to a great degree, and interstratified with beds of very soft
red shale. Under these lie 250' of greenish white, hard,
sandstone, down to the bed of the river in the gap, be-
neath which nothing can be seen, as the exposure is anti-
clinal.
No. IV at OrUsonia. PL LXXXV1, p. 650.
At Orbisouia, 10 miles further south, Black Log mount-
ain shows No. IY in Rockhill Gap in its three divisions.
The Medina white, 400' thick, consists of massive white
and gray, fine-grained, hard sandstone beds alternating in
the upper part with red and grayish shales. The Medina
*Professor Kogers estimated the middle division of No. IV in Logan Gap,
at 1000' ; of which the uppermost 500' consists of dark red flaggy beds of
mixed sand and mud, some of which contains curious pebbles of red shale
of unknown origin. Under these lie 100' of coarse red sandstone, loosely
cemented together, friable under the weather, some of them sprinkled with
small pebbles and showing a great number of iron stained spots. Under
these lie 400' of pale red sandstone beds containing pebbles of quartz and
fragments of slate apparently like No. III. These 1000' of reddish and more
or less pebbly soft rocks constitute the middle division of No. IV.
654 GEOLOGICAL SURVEY OF PENNSYLVANIA.
NO. IV. AT SPRUCE CREEK GAP. 655
red, 930', consists of soft brown and red clay sandstones
and shales ; the sandstones in the central part softer and
more friable and specked with iron. The Oneida is divis-
ible here also into two groups, the upper (158') consisting of
hard red and greenish gray, broken up sandstones with
conglomerates ; the lower (410') of hard massive greenish
sandstone and gray conglomerate strata.
No. 2 Vat Spruce Creek Gap.
In the gap of the Little Juniata through Tussey mount-
ain 20 miles northwest of Jack's mountain narrows, the
Medina white sandstone, 1000' thick, showing few pebbles,
but many impressions of the sea weed above mentioned,
descends from the crest of the mountain to the bed of the
river southward on a slope of 20. Under this lies 700' of
Medina red sandstones and shales. The next underlying
200' are concealed but probably belong to the middle divi-
sion, making it 900' thick. Under these concealed rocks, the
Oneida conglomerate appears with its massive coarse and
pebbly beds, apparently only 100' thick ; but the Spruce
creek tunnel fault at this place obscures the section. Frag-
ments of the Medina white, sliding from the crest of the
mountain, cover its southeastern slope and also the upper
part of its northwestern side ; for the thin beds broken up by
the weather into innumerable flagstones slide upon each other
down that slope ; and in this respect the surface show of
Medina formation in this part of the region is peculiar.
The best place to see this operation of gradual destruction
is in Jack's Narrows before mentioned ; where the formation
is thrown into a double anticlinal arch cut through by the
river. The two walls of the gap are slopes of about 30,
entirely covered from the crest of the mountain to the bed
of the river with a smooth and regular universal stone slide,
composed of millions of broken flags slipping over each
other farther and farther in their slow but never ceasing
descent. The material thus provided by nature has been
thankfully accepted by man ; and railroad engineers find
in this great stone slide an inexhaustible provision for the
finest railroad ballast that can be conceived.
656
GEOLOGICAL SURVEY OF PENNSYLVANIA.
LXXX/X-
Langtudifial Section ofJacts Mountain miavmy between Three Springs and Saltillu
shotting the subsidence at the Anticlinal at the end of the Mountajn.hyCha$.AAshbur
r.p.n*.
NO. IV. AT TYRONE GAP. 657
The ravine which descends into Spruce creek gap has been
excavated in the Medina middle; and the Juniata river
makes its very remarkable bend below the Spruce creek
station in order to use the lower part of this ravine for a
water way. The long hog-back in the bend (through which
the Pennsylvania tunnel has been driven) is made by the
Oneida conglomerate ; the outcrop of which slopes up the
mountain side and becomes the brow of the terrace which
surrounds Nittany and Canoe valleys. This terrace is the
prominent feature of the northwest slope of Tussey mount-
ain for many miles eastward.
No. IV at Tyrone Gap.
In the gap of the Little Juniata through Bald Eagle
mountain at Tyrone City, Formation No. IV stands verti-
cal, affording a fine opportunity for the study of its beds.
But all the beds are not visible, being concealed by the ma-
terial which has slidden from above. The section pub-
lished in Report T, page 17, and Report T3, page 144, is as
follows :
Sandstone, white Medina, 100 rb
Sandstone, red, with layers of red slate from 6" to 5' thick, 255'
Concealed interval, 540'
Sandstone, red massive, 84'
Sandstone, green slaty, 1' 8'
Sandstone, red, with a few layers of red shale, 87'
Slate, green, 0' 6"
Sandstone, red, 10'
Shale, red, 5'
Slate, green, . . 5'
Sandstone, red, 5
Sandstone, gray, 20'
Shale, red, 1'
Sandstone, gray, 10'
Shale, red, . f 0' 6"
Sandstone, red, 10'
Sandstone, grayish red, 15
Slate, red,
Slate, green, ... 16"
Sandstone, gray, 15
Slate, gray, 1
Sandstone, brown, 20
Slate, gray, 1
Sandstone, brown, 8
Shale, red, 6'
42
658 GEOLOGICAL SURVEY OF PENNSYLVANIA.
NO. IV. IN MILL HALL GAP. (
Sandstone, reddish brown, 75'
Slate, red, ... 1'
Sandstone, red and gray, 200'
Sandstone, red, 9'
Shale, red, 4'
Sandstone, red, 2
Slate, red, 3
Slate, green, 1
Slate, red, 4
Slate, green, ... 2
Sandstone, red, 6'
Sandstone, red, some little of it gray, 15'
Sandstone, red, 10'
Slate, gray, 2'
Sandstone, red, 18'
Slate, gray, 0' 5"
Sandstone, grayish brown, 12'
Shale, red 0' 3"
Sandstone, brown, 20'
Shale, green, 0' 2"
Sandstone, brown, 4'
tehale, red, 1'
Sandstone, brown and gray, and concealed, 150'
Sandstone, gray, and concealed, 409
Sandstone, gray, 320'
Sandstone, gray, and slaty sandstone, 440'
2906' 6"
In Tyrone gap, according to Mr. Sanders, the Medina
white measures 1068', the Medina red 668', and the Oneida
1160' making a total of 2896'. A crush fault (apparently
of no great magnitude) makes the statement a little doubt-
ful. It is evident from the section above given, that the
whole formation has a very different character along this its
westernmost Bald Eagle outcrop, from its character along
the Jack's mountain outcrop, 25 miles to the southeast.
Many of the beds of the upper Medina, although massive,
have a red color and might justly be thrown into the mid-
dle division (Medina red).
No. IV in Mill Hall Gap.
In the Bellefonte gap through Bald Eagle mountain, 30
miles to the northeast of Tyrone gap, the Medina white
may be said to have a thickness of 400' or 500'. The Me-
dina red here consists of thin bedded gray and red clay
sandstones, constituting three parts of the whole mass.
660 GEOLOGICAL SURVEY OF PENNSYLVANIA.
~~ XcT
Section tine J-% OCTOM Centre tomukip.
NO. IV. IN THE BEDFORD GAPS. 661
separated by and alternating with beds of red, gray and
greenish shale. In the uppermost beds have been found
stem-like vegetable forms (Scolithus vertical-is) which are
probably the casts of the burrows of worms going down
and coming up in the sand'on the shore of the sea ; its total
thickness say 500'. The Oneida is here again divisible into
two groups, the upper (380' thick) composed of greenish gray
slightly micaceous sandstones, specked with iron ochre, and
separated from each other by thin layers of finely lami-
nated greenish slates ; the lower (170' thick) a mass of hard
gray sandstone beds, entirely without pebbles, but com-
pletely covered (where exposed to the weather) with yellow
ochre specks produced by the decomposition of iron pyrites
disseminated through the whole rock, in what original form
has not been investigated. This iron speckled aspect of
the Oneida division of Formation No. IV is characteristic
of it throughout the central region of the State, and is a
peculiarity which marks it quite as plainly as the flagstone
slides mark the Medina upper division.
No. IV in Williamsburg Gap.
In the gap'of the Juniata river through Canoe mountain
in Blair county, the Medina white is a mass of white and
gray, line grained heavy sandstone beds, 550' thick. The
Medina red consists of softer, reddish brown, clay sand-
stone beds, a few beds of gray sandstone, and a great many
beds of red shale, subdividing a total thickness of 1050'.
The Oneida is as usual composed of massive greenish gray
and pinkish, iron speckled, very hard sandstone beds, in
all 500' thick.
No. IV in the Bedford Gaps.
In Bedford county the Medina white, still making the
crests of the mountain, is a mass of almost snow white,
line-grained, very hard and gritty rocks, 860' thick in the
Yellow creek gap through Tussey mountain, but growing
thinner southward, so that it is only 300' thick in the Rays-
town Juniata gap through Tussey mountain, near Bedford,
662 GEOLOGICAL SURVEY OF PENNSYLVANIA.
?'m(wy ftudt in, Spring
M?) limed fane
<3>erry Co
NO. IV. IN THE BEDFORD GAPS. . 663
and 200' in the gap through Evitt's mountain (T2, p. 91) ;
no fossils but the sea weed Arthrophyous being seen in
it at any exposure. The Medina red in the Bedford dis-
trict contains comparatively little soft shale ; its beds being
chiefly hard fine-grained red sandstone grits ; containing
innumerable pellets of ochreous clay, which when exposed
to the weather are dissolved out, leaving the rock in a
curiously pitted, or finely honeycombed condition. Flat-
tened lumps of red clay may be found by breaking the
rock of many of the beds ; and these suggest an explana-
tion for the universal iron speckled condition of the Oneida
beds.*
As for the Oneida or lower division of No. IV in Bed-
ford county, Dr. R. M. S. Jackson of the First Geological
Survey could find only 100' of beds which he could so call
in the gap of Will's mountain into Millikin's cove. He
suggested that the lowe'r part of it might be concealed by
a fault along the western edge of the cove, seeing that the
strata in Buffalo ridge are much broken and turned up ver-
tical. But Professor Stevenson, in report T2 on Bedford
county, could not recognize any Oneida rocks south of
Morrison's cove. Gray sandstones indeed appear in Raver's
creek gap through Tussey, on the Henrietta road in Wood-
*How these balls of clay enclosed in fine sand originated is a curious ques-
tion. It is also a matter of some moment to get any answer to the enquiry,
whether they were originally round, or whether they were deposited in their
present flat shape. For if they were originally round their flattened con-
dition now must be ascribed to pressure, that is, to the consolidation of the
Formation No. IV under the burden of all the formations up to the Coal
measures, which were afterwards laid down upon it. And this would in-
troduce a subject which has hardly yet received attention from geologists,
namely, the amount of compression and loss of bulk vertically which all
our formations have suffered in the lapse ot time, partly by the closer pack-
ing together of their sand and mud grains, but chiefly from drying out of
the original sea water with which they must have been for many ages com-
pletely soaked or water logged. For if this diminution of bulk could be
shown to bear a considerable proportion to the original thickness of sand
and mud deposits, the calculation, if made upon a sound basis of fact,
would materially modify the. speculations now so popular, oftentimes so
rash, and in all cases so unsatisfactory, respecting the mutations of the sea
level in various geological ages. For if our formations in drying have lost
only 5 per cent of their thickness, the total shrinkage in thickness of say
40,000' of Palaeozoic strata would amount to 2000'.
664 GEOLOGICAL SURVEY OF PENNSYLVANIA.
XCfif
tcJ^irom twc&ifoal ortion o foe
g^TT-rE?
K / I L L
NO. IV. IN THE BEDFORD GAPS. 665
berry township, and obscurely at two places on Banning' s
mountain ; but Oneida beds are certainly absent along the
Raystown Juniata in both Tussey and Evitts mountain
gaps. In fact Oneida sandstone beds were seen by him at
no locality in Bedford county more than 35' thick. At the
two places last mentioned there can be no question of con-
cealment by faults, for the top layers of No. Ill are regu-
larly overlaid by Medina red or brownish red shales con-
taining two fossils which unmistakably belong" to that divi-
sion(Ambonyc7im radiata and Rliynclionellacapax}2c&& th
Hudson river slates pass without any break of sequence
upward into Medina shales ; so that there can be no doubt
that the Oneida formation was not deposited in the bed of
the sea in this locality, even in the condition of tine sand.
Yet it must not be rashly concluded from this fact, that
dry land existed here. For had dry land existed it must
have been land of No. Ill raised above the sea level and
afterwards submerged to receive the deposit of No. IV.
But the moment a portion of sea bottom is lifted above
water level rain-erosion commences, and continues until re-
submergence ; and rain-erosion must leave its marks in the
shape of hills and hollows however small or low. Some
break in the continuity of the deposit must take pi ace, and
must remain visible ever after wherever the consolidated
rock strata are now exposed to examination. If no such
break appears we ma} 7 be sure that the sea bottom has not
been lifted to the air. Therefore if the Oneida format! on,
thick and pebbly further northeast, grows thinner and finer
and at length disappears going south, allowing the Medina
above it and the Hudson river below it to come quietly
together, it is certain that its disappearance is really and
surely due to the fact that the sediments were floated fur-
ther out into deep water according to their fineness, until
at length the finest material was exhausted, or, mingled with
equally fine material floated in from other directions.
666 GEOLOGICAL SURVEY OF PENNSYLVANIA.
Ml
ylkil Wafo^ap,
(mdjie/ne, reduc<o ft. ivneaf
NO. IV.- IN CLINTON, CENTRE AND LYCOMING. 667
No. IV in Clinton, Centre and Ly coming.
Following the Bald Eagle outcrop of IY eastward into
Clinton count}', the gaps at Lock Haven, Jersey Shore and
Williamsport furnish sections of it along a stretch of 40
miles.
In the gap at Millhall, near Lock Haven, the Medina
upper hard massive white, gray and red sandstones, not very
well exposed measures 695'. The middle division of in-
terstratified softer sandstones and shales measures 705'.
Under these lie hard massive sand rocks mostly w r hite; with
a few beds of gray, mottled with iron rust, 188'. Under
these, partly concealed, softer sandstones and shales, some
of them red, 118'. Under these, massive, hard, dark gray
and greenish gray, iron specked, flinty sandstones, 155'.
Under these are hard and massive sandstones with con-
cealed intervals of softer rocks, 440' ; which makes a total
thickness of 2301'. (G-4, 129). It is evident that no useful
classification of the beds of the whole formation into three
divisions can be made out of the mere terms of this sec-
tion ; but it will be shown in its proper place that where
the eye of the geologist is at fault, the hand of nature works
with unerring certainty, and carves the shape of the mount-
ain in accordance with the larger groupings of the hard and
massive beds.
In the gaps issuing from Nippenose valley and Mosquito
valley in Lycoming county the rocks of No. IV are not
well exposed. The Medina upper hard sandstone is esti-
mated by Mr. Platt at only 100' ; the middle red division
he makes 1200' ; arid the Oneida hard sand rock only 15' ;
the total being only 1375' (G-2, 29). The contrast between
the section at Mill Hall carefully measured by Dr. Chance
and this roughly estimated section of Mr. Platt at Jersey
Shore and Williamsport is very striking, and not easily
explained. It certainly affords no safe basis for generaliz-
ing on the extent, thickness or method of the deposits.
668
GEOLOGICAL SURVEY OF PENNSYLVANIA.
NO. IV. ALONG THE GREAT VALLEY. 669
No. IV along the Great Valley.
Passing now to the long outcrop of No. IY, which bor-
ders the Great Valley, we have, first, at the gap of the
Susquehanna above Harrisburg an expression of the for-
mation totally different in character from anything observ-
able in the outcrops northwest of it toward the Allegheny
mountain. The Medina upper division consists of a series
of comparatively thin white sandstone beds, alternating
with greenish and yellowish slates ; some reddish sand-
stones occurring among the upper layers showing impres-
sion of marine plants ; altogether making only 300' or 400'.
The absence of massiveness here in the upper division of
No. IV is quite remarkable. The consequence is that in-
stead of making the crest of the mountain, these upper
beds crop out below the crest on the southern side, over
the outcrop of the Oneida ; the crest being made by the
Iron sandstone of the Clinton formation No. V. that is,
in Perry county.
The Medina middle soft red division of No. IV is here
entirely wanting ; and the geologist must travel along the
mountain westward toward Franklin county to find it again
appearing in the ridges which enclose Path Valley, but only
feebly developed. Or he must cross Perry county north-
westward to find it coming into the series in the gaps of
the Tuscarora range. If he continues further northward
to the Shade mountain, Blue Ridge and Black Log mount-
ain gaps, he will find it much increased in thickness. Be-
yond these to the northwest are the sections in Jack's mount-
ain, Tussey mountain, and the Bald Eagle range, which
have already been described, where it attains its maximum
thickness.
No. IV at the Susquehanna Water Gap.
But, in the Susquehanna gap above Harrisburg the Oneida
makes a great mark rising steeply to the top of mountain,
along which its rocky outcrop runs, on the southern slope.
It is about 70' thick, 40' of which consists of white sand-
stone beds containing pebbles ; under this an exceedingly
670 GEOLOGICAL SURVEY OF PENNSYLVANIA.
Xcvi.
NO. IV. AT THE SUSQUEHANNA WATER GAP. 671
coarse, heterogeneous, red pudding-stone, 5' thick. Under
this, between it and the uppermost layers of Hudson River
slate, there is a concealed space of 40' or 60'. How much
sliding and faulting has taken place in this interval, or how
much of it is occupied by concealed sandstones cannot be
made out. The wall of Oneida exhibits so many oblique
slips and fault joints that its present thickness may be dif-
ferent from that which it had when it lay horizontally at
the bottom of the sea. The most interesting feature of
this famous exposure (apart from the fact already men-
tioned that the formation is here pushed over the vertical
to a reversed south dip of 70) is the five foot 'coarse pud-
ding-stone. As this lies at or near the bottom of No. IV,
and more or less directly upon the slates of No. Ill, it is
certainly an indication of some disturbance having taken
place in some other and perhaps distant district of the
earth's surface. But it is useless to speculate upon the
origin of a bed, composed of pebbles and fragments of all
kinds, since we are entirely ignorant of the depth of water
which then and there existed, of the nature of the tide-
runs or other currents which could transport the material,
and of the shape, character or location of the shore lines
which bounded the then water basin.
It serves no good purpose to suggest that we have here a
shingle on a sea beach. It would be equally useless to
suggest an isolated gravel bank in the midst of the sea.
Towards the west, for a thousand miles, no land could have
existed at that time ; nor for less than three or four hun-
dred miles towards the north. Our South mountains, and
in fact all southeastern Pennsylvania was then not only
under water, but covered by the limestone and mud for-
mations No. II and III. If the great mountain mass of
North Carolina was at that time out of water, which is
very doubtful, it was nearly 500 miles distant to the south.
All the highlands of New Jersey were at that time sub-
merged. The Adirondack mountains in northern New
York, and perhaps parts of New England, may possibly
have been out of water, and possibly the Oneida pebbles were
derived from those sources (but were certainly subsequently
672 OEOLOGICAL SURVEY OF PENNSYLVANIA.
#/ / XCVH
. fffi'/fy
of If 4
^-!> M i . . '.I h^
NO. IV. AT THE SCHUYLKILL WATER GAP. 673
submerged, as the Barnardston fossils show). But it would
defy the keenest genius to make out the case, or paint the
picture of the transaction in colors which would not fade
into an ^indistinguishable gray under the light of precise
enquiry. And the hopelessness of the attempt is accented
by a fact which seems to be never alluded to by those who
generalize on such subjects ; namely, the fact that our for-
mation No. IV while being deposited in the Appalachian sea
of America was at the same time being deposited in the
prolongation of that sea which reached Europe ; being re-
cognized in England under the name of the May Hill sand-
stone ; and it will be shown in discussing Formation No.
VII that this critical fact was repeated in the case of the
OrisJcany sandstone which was deposited in the United
States at the same time that it was being deposited in
France ; specimens from that formation, full of the same ani-
mal forms and presenting exactly the same aspect, having
been collected from the outcrops on both sides of the
present Atlantic.
No. I Vat the Schuylkill Water Gap.
A topographical contour map of the Schuylkill Water
Gap at Port Clinton made by Mr. Chance, with careful
measurements of the five groups into which No. IV is there
subdivded, gives us the following description of it :
Three prominent ribs of sandrock rise vertically from the
bed of the river to the north slope of the crest of the mount-
ain. No distinction can be made in the Medina between
an upper white and a lower red division. At the top rest
90' of Upper Medina gray sandstone beds, supported by
480' of iron stained shales ; under which are 60' of Lower
Medina white sandstone beds supported by 600' of iron
stained shales ; and at the bottom, 200' of Oneida white
sandstone and gravel beds, which make the crest.*
*This is a rare occurrence, due to the great thickness and massiveness of
this rib. The terrace on the north slope is made by the outcrop of the com-
paratively thin and unsupported Upper Medina rib. See cross-section,
ng. 4, plate LIT, on p. 554 above.
43
674 GEOLOGICAL SURVEY OF PENNSYLVANIA.
At this interesting locality the bottom of No. IV is wholly
separated from the slates of No. Ill by a vertical fault, on
the north side of which the sandstones of IV rise vertically
into the air, making the crest and north slope of the mount-
ain. On the south side of the fault the slate formation
No. Ill is sheared off like a cake of cheese, the edges of
the slates abutting nearly horizontally square against the
upturned bottom plate of Oneida conglomerate. It is im-
possible to affirm that it is actually the bottom layer of the
Oneida ; but there is very little reason to doubt it ; seeing
that when the break took place, and the whole mass of No.
IV was turned up at right angle, it is probable that it was
turned up as a solid mass ; and that the lower surface of
the bottom bed acted as a grinding surf ace against the edges
of the slates. As no verbal description can give a clear
idea ^of this phenomenon the section is presented in the
figure cited in the last footnote.
The Schuylkill Water Gap is 50 miles east of the Sus-
quehanna water gap ; and in these 50 miles the character of
the formation has evidently changed in an extraordinary
degree ; and this change goes on becoming more and more
striking eastward.
No. 1 V Lehigli Water Gap.
At the Lehigh Water Gap (25 miles east of the Schuyl-
kill Water Gap) Dr. Chance's measured section gives the
following details : Upper sandstone rib 85' ; upper ferru-
ginous shales 180' ; Middle gray sandstone rib 70' ; lower
ferruginous shales 330'; (total Medina 665';) Oneida sand-
stones, some of them pebble-rocks, 290' ; Oneida massive
conglomerate 170' ; (total Oneida 460') ; total of Forma-
tion No. IV, 1125'.
We see that the pebble-rock, which at the Susquehanna
gap was less than 100' thick and at the Schuylkill gap 200',
is at the Lehigh gap nearly 500' ; constituting everywhere
from the Susquehanna to the Lehigh the central rib of the
mountain and sometimes its crest ; while the middle and
NO. IV. AT THE DELAWARE WATER GAP. 675
upper sandstone ribs crop out as terraces and benches
along the northern slope.*
No. IV at tlie Delaware Water Gap.
At the Delaware Water Gap (25 miles. still further east)
the gradual change in the constitution of No. IV produces
another feature, namely, the subdivision of the Oneida into
three, the Medina continuing to be sub-divided into four.
We now have seven distinct subdivisions of the formation
No. IV as follows ; Upyer Medina sandstone'rib 200' ; upper
ferruginous shales with some sandstone beds 530' ; Lower
Medina sandstone rib (here a white conglomerate) 200' ;
lower ferruginous shales with the sandstone beds 110' ;
(total Medina 1040') ; Upper Oneida gray sandstone rib
75' ; intermediate shales with sandstone beds 240' ; Lower
Oneida white conglomerate rib 210' (total Oneida 525'} ; total
thickness of No. IV, 1564'. f
At the Lehigh Water Gap there is some doubt about the
relation of the bottom bed of Oneida to the slates of III on
which it rests ; but at the Delaware Water Gap there is no
confusion or concealment whatever ; the under surface of
the bottom bed of the lower division of the Oneida con-
glomerate rests quietly and regularly upon the uppermost
sandy slates of No. III. And, what is more important
* At the Lehigh the Upper Medina sandstone makes the crest, but as it is
comparatively thin the crest is not sharp ; and as it is supported by the sec-
ond rib, with only 170' of hard shales between them, the two ribs act like
one, and as if 235' thick, making a very high gently rounded crest See
figure 3, LII, page 554. The south slope of the mountain becomes steeper
and steeper across the 330' of hard shales ; and becomes 35 across the
290' of Oneida sandstone and 170' of Oneida conglomerate, more than two-
thirds of the way down to the foot Here the slates of III commence,
and the slope suddenly becomes gentle. It is a remarkable contour for the
mountain of IV, well worthy of careful study. The outcrop which was at
the very crest at the Schuylkill is here at the Lehigh nearly at the south
foot of tbe mountain ; not on account of dip, but on account of the differ-
ent arrangement of the rock ribs and parting shales in the body of the
mountain.
t Here the Oneida upper sand rock rib, thin as it is, makes the crest, be-
cause it is so closely supported (within 110') by the huge Lower Medina
sand rock rib, and by the very sandy character of the Oneida middle shales.
The Oneida conglomerate makes precipices along the southern slope half
way down the mountain. See cross-section, PI. LXXX, p. 638.
676 GEOLOGICAL SURVEY OF PENNSYLVANIA.
still, the uppermost beds of No. Ill are here so sandy as to
contain thin beds of sandstone, showing a regular proces-
sion of deposits, and a sort of passage from the slaty
kind (III) to the coarser sandy and gravelly kind (IV).
And yet the transition is in fact instantaneous ; as if avast
quantity of grav.el was deposited upon a level sea bottom
of dark sandy mud. We are again left in total darkness
as to the cause of this remarkable operation. But after
all, it is no more extraordinary than the way the May Hill
sandstone of England rests upon the shales and limestones
of lower Silurian Age.
No. IV in New Jersey.
The Kittatinny mountain (called Shawangunk mountain)
after crossing the Delaware river at the Water Gap runs on
for 35 miles to the north corner of New Jersey at Port
Jervis. Oneida conglomerate (Shawangunk grit) is de-
scribed in the Geology of New Jersey (1868, p. 146) as a
mass measuring (at Otisville) 800' or 900' thick, composed en-
tirely of beds of conglomerate and sandstone. The lower
part is a mass of quartz pebbles, from one quarter to three
quarters of an inch in diameter, in a light colored quartz
cement. In the beds above, the pebbles become smaller ;
and near the top they can hardly be distinguished from the
paste in which they are imbedded, the whole rock being a
massive compact quartzite. No fossil forms have been
found. Some of the beds contain crystals of iron pyrites
which have yielded to chemical assay as much as $11 of gold
to the ton, This occurs at the bottom of the formation next
the slates of III. The lead ore veins which traverse the
rock will be mentioned directly.
I The Medina beds outcrop along the northern slope of the
mountain descending to the Delaware river. Their esti-
mated thickness where the Erie railroad crosses the mount-
ain east of Port Jervis is 800'. The two formations Me-
dina and Oneida are here seen to pass into each other by
a series of alternations, white and red, fche white being
Oneida, the red Medina. These colors strongly contrast
and distinguish the two formations. The Indians called
NO. IV. IN NEW YORK. 677
the mountain "Shamgum" the white rock. It is evident
from the change of color that the sea water at the begin-
ning of Medina time, began to receive large accessions of
iron ; but there was not at any time deposits of iron ore. The
red Medina sandstones are interstratified with reddish
shales ; and these are so abundantly traversed by trans-
verse cleavage planes as to give the rock in some places the
appearance of a red roofing slate, dipping steeply across
the bedplates towards the southeast ; but the coarser and
harder brownish red sandstones do not show this cleavage
and exhibit the true northward dip. Occasionally a gray-
ish green shale occurs. The bottom Medina beds (next
over the Oneida) are all sandstone, made up of grains of
quartz, some of them containing small pebbles of white
quartz, interstratified with soft shales ; while the upper
Medina beds are nearly all reddish shale (much split by
cross cleavage) interleaved with thick red and grayish sand-
stone beds. No fossil of any kind except a sea weed has
been found ; and this is the more remarkable because, ex-
cellently well preserved ripple marks are common, in fact
almost universal.
No. IV in New Yoik.
The Shawangunk mountain in New York runs on north-
east about 45 miles, to within 10 miles of the Hudson, and
abruptly ends at Rosendale where the Rondout and Wai-
kill valleys come together. Leaving New Jersey "the mount-
ain has a crest of white Oneida, and a northern slope of
red Medina. But advancing northeastward the Medina
rocks disappear and at last the mountain consists exclu-
sively of Oneida beds, estimated by Mather at 500' running
down to 150' and even as thin as 60'. Some red beds at the
top would seem to indicate that the Medina is slighly rep-
resented ; but no division between the two formations is
possible ; and it will be seen hereafter that the next supe-
rior formation No. V thins away in the same direction, let-
ting the limestone of No. VI rest upon the beds of No. IV.
These details respecting the geology of New Jersey and
New York are given here merely for the purpose of show-
678 GEOLOGICAL SURVEY OF PENNSYLVANIA.
ing that the variations in Formation No. IV throughout
Pennsylvania are not to be compared for magnitude with
its variation in this New York district. The mountain in
New York is broken by great cross-faults which traverse
also the formations above it and below it. In fact the re-
gion bordering the Hudson river valley has been shattered
by the earth movements which elevated New England; and
probably it is to the greatest of these faults that the mount-
ain owes its sudden termination.
Lead ore veins in No. IV.
The remarkable lead veins which traverse No. IV in New
York are among the consequences of the shattered condi-
tion of that region. Such lead veins are not to be expected
in Pennsylvania where the outcrop mountains of No. IV
exhibit few cross fractures. In the early settlement of
America, Indians and hunters searched everywhere for
galena to furnish themselves with bullets. Hundreds of
traditions of Indian lead mines have been handed down,
most of which are pure fictions. Indians and hunters cer-
tainly did find lead in certain places and carefully con-
cealed their discoveries as long as it was possible to do so ;
but probably every such actual lead locality is now known,
and are few in comparison with the great number of fic-
titious places. Most, if not all of the actual veins have
been repeatedly explored, and some of them mined at con-
siderable cost, none of them to profit. Forty years ago
the Ellenville mine at the base of the Shawangunk mount-
ain, the Ulster mine near Red Bridge 600 or 700' up the
side of the mountain, and the Shawangunk mines near
Wurtsboro in Sullivan county, N. Y., 600 or 700' up the
mountain, were all in operation. They were all abandoned.
In the Ellenville mine some lead and zinc were obtained. In
the Ulster mine masses of zinc, lead, copper, and iron
pyrites were obtained. In the Shcwangunk mine three
masses of lead ore were taken out weighing from 800 to 1400
pounds. But the lead veins were only 2' or 3' thick, and
the ore very irregular. The abundance of finely formed
LEAD ORE VEINS IN NO. IV. 679
rock crystals, together with the mixture of ores, show that
they were deposited from solution in the cracks which tra-
versed the region after it had been shattered by the great
earth movement which took place at the end of the coal
age. It is idle to look for such veins in No. IV in middle
Pennsylvania. The same may be said of gold. Although
the lower beds of the Oneida are largely made up of gold-
bearing quartz, of course they cannot be considered in any
sense ancient glacial placer gravels ; and free gold has
never been reported. What gold exists is in the quartz
pebble itself. It is perfectly certain that no gold mining
can be successful in any of the mountains of No. IY in
Pennsvlvania.
680 GEOLOGICAL SURVEY OF PENNSYLVANIA.
J/ltJd-c/i Spring on Sinking Cr.
Lin.
Canoe Mounkwn terrace and linking valley.
TOPOGRAPHICAL FEATURES OF MIDDLE PENNA. 681
CHAPTER LII.
Topograplucal features of middle Pennsylvania.
The facts presented in the foregoing chapter introduce
the subject of the topography of the central belt of Penn-
sylvania, especially of that half of it which stretches from
the Susquehanna river to the Maryland state line : for this
topography has for its most striking features the bold ridge-
outcrops of Formation No. IV.
It has already been said that all the Pennsylvania mount-
ains from the North mountain of the Great Valley to the
Bald Eagle mountain facing the Allegheny, in the country
west of the Susquehanna river (with only three excep-
tions) are mountains of Formation No. IV*.
The mountains of No. IV may be classified in three
groups of zigzags, so complicated in their shape that they
can only be described by a map. To the inhabitants of the
various counties in which these groups stand they seem
like separate mountains, and so each has received some
separate local name.
Names of Mountains of IV.
The number of local names is very great ; the prominent
ends of the zigzags being usually named after some settler,
like Parnell's knob and Jordan's knob in Franklin county,
*Two of these exceptions are in Perry county, namely; Cove mountain,
ten miles and Buffalo mountain twenty miles above Harrisburg, which are
mountains of No. X, and belong to the anthracite region of eastern Penn-
sylvania. The third exception is that of Sideling hill and Terrace mountain
in Huntingdon county, surrounding the Broad Top coal basin, and continu-
ing under various local names, like Harbor mountain and Town Hill, into
Maryland, all mountains of No. X. The Broad Top mountain enclosed by
them is made by No. XII capped with coal measures. A fourth exception
might be mentioned in the case of Great and Little Savage mountains, in
Somerset county, surrounding the Cumberland coal basin in Maryland ; but
this outcrop of No. X and XII is nothing but a zigzag of the Allegheny
mountain and belongs properly to the general bituminous coal region of
western Pennsylvania.
682 GEOLOGICAL SURVEY OF PENNSYLVANIA.
Sidney knob in Fulton county, Jacks mountain in Union
county, Tussey's mountain, Dunning' s mountain and
Evitt's mountain in Mifflin, Blair and Bedford counties.
Others have been named after the animals that haunted
them in early times ; Bear Meadow mountain in eastern
Huntingdon ; the Buffalo mountains in Union ; White Deer
and Bald Eagle mountains in Ly coming. Tuscarora mount-
ain, ranging through Juniata county, was named after the
principal tribe of Indians in middle Pennsylvania.. Stand-
ing Stone mountain on the borders of Huntingdon and
Mifflin, was named after a remarkable monolith or solid
stone pillar 70' high, which once stood on the bank of the
Juniata, at the mouth of the creek, near the present town
of Huntingdon. Around it the grand council fire of the
tribes was lighted. Sometimes a name was repeated ; as,
for instance, Path Valley mountain, along which the south-
ern county line of Centre runs, which has no connection
whatever with the mountains surrounding Path valley in
northern Franklin county. Several projecting spurs are
called Dividing ridge, or Dividing mountain, because they
separate two parts of an enclosed valley. German settlers
from the Rhine, familiar with the name Siebengebirge,
called the knot of ridges between Kishicoquillas valley and
Brush valley the Seven mountains ; but their ends toward
the Susquehanna, in Snyder and Union, retained their
Indian name of the Buffalo mountains ; a proof that the
bison roamed through Pennsylvania, when the beaver made
its dams on many of our streams, and herds of elk ranged
through the Allegheny uplands.
Three groups of mountains of IV.
1. The southernmost group of mountains of IV lies be-
tween the North mountain of Cumberland and Franklin
and the Tuscarora mountain which ends at the Juniata at
Millers town. The eastern zigzags are represented in lig. 3,
pi. LXXIV, p. 626. They enclose the fertile valleys of
Perry county, Greenbrier, Kennedy's. Henry's, Shafer's,
Little Illinois, Sherman's, and Horse valleys, with Path
valley, Burn's valley, and Amberson valley in Fulton
THREE GROUPS OF MOUNTAINS OF IV. 683
county, issuing southward upon the Great Valley at Mer-
cersburg. This group is extended southward through
Fulton as Sidney knob, Tuscarora mountain, and Cove
mountain surrounding McConnellsburg Cove in Fulton
county, into Maryland. It includes also the isolated mount-
ain which ends in ParnelPs knob ; and the two mountains
which project from Maryland toward Mercersburg.
2. The middle group of mountains of IV., is of a pecu-
liar character. Tt resembles three long narrow canoes
moored side by side, but projecting beyond each other ; or
rather three canoes floating bottom up, each one with its
bottom knocked out. They are in fact the eroded tops of
three long closely folded anticlinal arches of No. IV, sep-
arated from each other by equally long narrow and closely
compressed basins filled with Formation No. V. (a)The
southern anticlinal, having West Shade mountain for its
south dipping and Black Log mountain for its north dip-
ping outcrop, extends from Fort Littleton on the Fulton
county line to within ten miles of the Juriiata at Mifflin-
town. (5)The middle anticlinal, called Blue ridge, ex-
tends from the Horse Shoe bend of the Juniata at Newton
Hamilton to the Juniata river above Mifflintown. (c)The
third extends from the Juniata river at Lewis town to within
8 miles of Sslinsgrove, on the Susquehanna, in Snyder
county. The shape and arrangment of these three is
shown in the Vignette Map of the State at the beginning of
this volume. Nothing in topography is more beautifully
symmetrical ; nor can anything illustrate to greater advan-
tage the plication of the formations in middle Pennsylvania.
3. The third group of mountains of No. IV is of so com-
plicated a character as to defy description in words, and is-
therefore given in outline in the Vignette just mentioned.
In this figure a black line represents the Medina white
sandstone outcrop which everywhere in this group, extend-
ing from the Susquehanna at Muncy in Ly com ing county
to the Maryland line, makes the mountain crest; while the
broken line alongside of it represents the Oneida gray
sandstone outcrop which everywhere in this group forms
a bold terrace on the mountain flank. The southern
684 GEOLOGICAL SURVEY OF PENNSYLVANIA.
border of this group is the noble ridge of Jack's mountain,
which borders the Lewistown valley on the north and for 50
miles, shuts in behind it the fertile Kishicoquillis lime-
stone valley, bordered on the northwest by the Standing
Stone mountain, and on the north by the Seven mountains,
which spread (northward) as Short mountain, Brush mount-
ain, Nittany mountain, Buffalo, White Deer and Bald
Eagle mountains as far as the Williamsport valley. From
the western end of the Seven mountains projects Tussey's
mountain which runs on uninterruptedly about 100 miles
to the Maryland line, shutting in behind it the fertile lime-
stone valleys of Penn's creek, Brush creek, Spruce creek,
Canoe valley and Morrison's cove. The Bald Eagle out-
crop is the second finest in the State, extending along
the West Branch of the Susquehanna for 30 miles, from
Muncy to Lock Haven; than onward along the Bald Ea-
gle creek for 50 miles, from Lock Haven to Tyrone City;
thence onward along the upper Little Juniata for 15
miles, to Frankstown; then returning to the Little Juniata
(13 miles) as Brush mountain ; bending back and running
south (20 miles) as Canoe mountain; turning and running
north (6 miles) toward Hollidaysburg as Lock mountain;
resuming its south course as D tinning' s mountain (25 miles)
it bends round Dutch corner and runs south (30 miles) as
Evitt's mountain into Maryland. Isolated geographically
from this outcrop on the west is the anticlinal of Will's
mountain and Buffalo Ridge, extending from Bedford (25
miles) to the Maryland line.
This long and perhaps tedious enumeration of the mount-
ains of IV in middle Pennsylvania, west of the Susque-
hanna river, will interest the people of that part of the
State who will now understand the geological identity of
the labyrinth of mountain ridges among which they live.
But its principal value arises from a single geological
idea, namely : that this continuous series of mountain
crests and slopes are all made in one and t the same way,
out of one and the same set of rocks, exhibiting every-
where the same internal constitution and differing only, (1)
in the thickness of the beds or groups of beds at one
THREE GROUPS OF MOUNTAINS OF IV. 685
place and another, as has been fully explained in the last
chapter ; and (2) in the various angles to the horizon, at
which their strata have been tilted up.
It now remains to show, first, why these mountains some-
times run in straight lines parallel to each other for many
miles; secondly, why these parallel lines sometimes come
together at both ends, as do the gunwales of a boat at the
prow and stern; thirdly, why in other districts they unite
in a series of zigzags; fourthly, why the opposite points of
such a series of zigzags have two totally different charac-
ters, one long and sloping gradually into the plain, the
other high, sharp and abrupt, projecting like a knob into
the air ; fifthly, why the mountains of the first or southern
group have only one crest and two slopes, whereas the
mountains of the middle and northern groups have a crest,
a long continuous slope on one side, and a bold terrace half
way up the slope on the other side; sixthly, why the Bald
Eagle mountain in Centre county has two crests of e'qual
height and no terrace ; seventhly, why the terraces are cut
through at short and regular intervals by double headed
ravines; and, eighthly, what all this teaches us respecting the
great rock arches which once rose high in the air, but have
long since been removed and swept into the Atlantic, furn-
ishing collateral evidence that the surface of Pennsylva-
nia is still being slowly but continuously fretted down
toward the level of the sea.
Before taking up these several items it is essen tial to the un-
derstanding of the subject that the reader first imagine For-
mation No. IV as originally lying in a continuous and
nearly horizontal sheet, deeply buried beneath Formations
V, VI, VII, VIII, IX, X, XI, XII, and all the coal meas-
ures from XIII to XVII. He must then picture to himself
this continuous sheet Formation No. IV, with all the forma-
tions beneath and above it pressed sideways and folded
into arches and troughs also under western and northeastern
Pennsylvania, just as we see it at the surface in middle
Pennsylvania west of the Susquehanna. Beneath the
anthracite coal basins it lies at various depths from
10,000' to 20,000'; but between the basins the tops of its
686 GEOLOGICAL SURVEY OF PENNSYLVANIA.
great arches approach much nearer to the surface; and one
of them actually comes to the present surface in Montour's
ridge at a single point between Danville and Sunbury,
where, in a ravine descending to the North Branch of the
Susquehanna, 37' of its upper beds are actually exposed
(See G7, p. 114). The mountainous exhibition of it at the
present surface west of the Susquehanna is the conse-
quence of a gradual upward slope of the whole formation
from beneath the anthracite country, westward. Going west-
ward the arches rise first, like the backs of whales issuing
from the surface of the sea, covered with soft red shales of
Formation No. V, and gradually lifting themselves higher
and higher into the air. This is why all the eastern ends
of all the mountains of IV, facing the Susquehanna valley,
have one and the same character of long gently sloping
mountain noses.
Parallelism of mountains of IV.
A. The first point mentioned above is the parallelism of
the mountains of IV. This parallelism is perhaps the most
remarkable feature of the topography of middle Pennsyl-
vania. It is a consequence of the extraordinary symmetrical
shape of the anticlinal arches, which can be compared to
nothing better than the long even folds in heavy woolen
carpets when pushed sidewise over a floor. The formations
composing each fold may be well explained by the annual
layers of wood in a fallen tree trunk which arch over each
other, flat along the top, and steeply sloping on the sides.
Now let a lumberman adze off the upper part of such a
tree trunk, reducing it to a flat surface, he will expose
the edges of the wood-layers in two sets of parallel lines,
one set to the right and the other to the left ; exactly
corresponding to each other ; the uppermost layers being
the farthest apart, and the lowest layers to which his work
reaches occupying a middle line over the center line of
the log.
This it precisely what nature has done in her carpentry
work upon the long prostrate anticlinal folds of the Palaeo-
zoic formations ; only with a difference of tools. Instead
PARALLELISM OF MOUNTAINS OF IV. 687
of the carpenter's adze, she has employed frost, the thaw-
ing heat of sunshine, and the transporting power of rain
water. With these tools everlastingly at work she has
planed off all the anticlinal arches of middle Pennsylvania
nearly to a common level.
But the difference in the tools employed by the carpenter
and by nature makes a signal difference in the neatness of
work done in the two cases. The adze and jack plane make
no account of variation in hardness or softness of the several
layers of wood ; the edges are all reduced to the same
plane surface ; for such tools have no selective power and
care nothing for either the resistance or the compliance of
the wood which they remove. But the tools of nature ex-
ercise a kind of selective judgment ; or, rather, they are
sensitive to the slightest differences of hardness or softness
in the rocks upon which they operate. If we could ascribe
intelligence to nature we should be obliged to say, that she
has no intention to produce an even smooth topography, that
is, to reduce the surface of the State to a perfectly level
plane. Her water work has gone further into the softer
rocks, leaving the harder outcrops elevated, and the hard-
est and most massive formations standing out as mountain
ridges. But her manner of working has been essentially
the same as that adopted by the carpenter who, instead
of the rapid action of adze and plane, should content him-
self with the slow and tedious operation of sandpaper,
would himself produce the same variety of parallel ridges
separated by creases on his log of wood.
The parallelism of any two mountains of IV on two
sides of any anticlinal which extends for many miles
teaches us two facts :
1. We learn that to have exact parallelism in long straight
outcrops the crest of the anticlinal must be level for a long
distance ; for it is evident that if the crest of the anticlinal
slope upward the opposite outcrops must diverge ; if it
slope downward they would approach each other. (2) We
learn that the characteristic form of our anticlinal arches
cannot belong to one formation, but to a whole and very
thick series of formations, all folded together. This can
688 GEOLOGICAL SURVEY OF PENNSYLVANIA.
be easily understood by crumpling two substances even
as different in thickness as silk and woolen ; or by com-
paring the short irregular angular crimpling of one thin
sheet of paper with the ample and regular fold of an entire
ream of paper. The Palaeozoic formations, lying upon
each other like a pile of Canada blankets, could not have
been pressed by the earth movement into any arches and
troughs not of magnificent length, height and depth, and of
beautiful symmetry. Therefore it must be kept in mind
that we are dealing not with a few layers of sandstone, but
with 40,000' of superimposed sediments ; and that when
they were thrust into anticlinals and synclinals they all
moved together, yielding and adjusting themselves to each
other, especially the softer to the harder, but yielding to
the earth movement as if they all constituted one single
formation.
Convergence of mountains of IV.
B. The second point to be noticed seems at first sight a
violation of the principle just stated ; for the parallelism
is not perfect and universal ; it has its variations ; but these
variations, when explained, will be seen to be essential to
the principle. However many miles two mountains of IV
may run parallel, they are sure sooner or later to approach
and unite at one end or at both ends. If this occurs at
both ends it shows that the anticlinal fold dies down in
both directions.
The student of our geology must be careful to make a
strong distinction in his mind between the end of an anti-
clinal mountain and the end of its anticlinal fold. The
mountain comes to an end because two parallel outcrop
mountains have converged and sink together beneath the
present surface. But the anticlinal fold itself keeps on,
carrying the formation deeper and deeper In this way one
formation disappears in a loop at the surface and is replaced
by another further on, also in the shape of a loop. Following
the axis of an anticlinal fold we have say first an arch of No
II in the valley coming to a point ; then, a loop of No. Ill,
filling up the end of the valley; then a loop of No. IV mak-
MOUNTAIN SPURS OF NO. IV. 689
ing the end of the double mountain; on the outside nose of
which is a loop of No. V settling into the plain ; then a
loop of the limestone formation No. VI descending be-
neath a looped ridge of Oriskany sandstone No. VII ; which
descends beneath a rolling hill country of No. VIII, ending
in a grand mountain cove of red sandstone No. IX
capped with white sandstone X; sinking as an anticlinal
nose into a deep loop valley of the red shales of XI, en-
closed between opposite dipping mountains of the Conglom-
erate XII, separating two coal basins.
This is the rule in all cases where the anticlinals are of
the first order of magnitude.
Mountain spurs of No. IV.
C. A third point to be explained is the production of
groups of mountain zigzags. This requires a little more
strenuous effort of the imagination, but it is merely a com-
plicated form of what has just been described. When the
earth-movement pressed the whole series of Palaeozoic for-
mations into folds it obeyed a thousand variations of local
stress and strain, and produced therefore not merely a few
grand arches of the first order one or two hundred miles in
length, but scores of folds and wrinkles of the second and
third order of far inferior height and length. These sub-
ordinate folds may properly be considered mere parasites
of the great anticlinals ; they are, in fact, wrinkles on the
descending sides of the grand arches. But these smaller
arches bring the outcrop of No. IV to the surface and re-
turn it underground in the same way, but more rapidly
and locally. They produce the same topography, but on a
smaller scale. Each minor fold has its two opposing
outcrops of No. IV, coming together in the direction in
which the fold dies down. Where there are six such minor
folds side by side, all dying down in one direction (say
eastward, as in Snyderand Union counties) there are neces-
sarily as many pairs of outcrop mountains of IV one on
each side of each fold, producing a group of mountains in
zigzag, with six points in one direction, and as many in the
other. Perhaps the best way to comprehend this phenom-
44
690 GEOLOGICAL SURVEY OF PENNSYLVANIA.
enon, would be to take a sheet of corrugated zinc roofing,
and hold it slanting in a basin of water. The edge of the
water will make similar zigzags against the surface of
the tin. The more erect the zinc plate is held the shorter
will be each zizzag. If the plate be held nearly flat, one end
scarcely below the water and the other scarcely above it,
the zigzags will be long and sharp pointed. By varying the
shape of the bends in the tin plate, that is, by represent-
ing anticlinals and synclinals of different height, breadth
and sharpness, all sorts of variations in the zigzag water
line can be got, and all the variations of our No. IV. mount
ain zigzags may be imitated.
The inelasticity of sand and mud deposits greatly helps
us to explain their present folded condition. It cannot be
too of ten repeated, that, when the earth movement took place
the whole 40,000' of Palaeozoic formations were still in a
moist and plastic state. Had they been of any dry, hard,
elastic material they would have been bent into a very few
perfectly regular folds, each formation sliding upon the sur-
face of the one beneath it, and none of them wrinkled.
But the actual mass of mud and sand deposits being wet
and plastic, was necessarily, when thrown into folds as a
whole, compressed into ten thousand subordinate folds and
wrinkles. The great anticlinals are none of them mathemat-
ically perfect vaults. Their opposite sides do not descend
in smooth unvarying curves into the synclinal troughs, but
wave and halt and pitch irregularly in their descent. In
geological language, the dip is constantly changing to
steeper or less steep, and is occasionally reversed ; so that
on the long slope of a grand anticlinal there are always
seen to be one or more subordinate rolls'and basins. When
the bottom of the long anticlinal slope is at last reached,
we are in the middle of a great synclinal basin, and begin
to ascend the long wavy slope of the next parallel grand
anticlinal. Thus, anticlinals and synclinals virtually oc-
cupy the same ground ; each anticlinal measuring in breadth
from the center line of one synclinal across the arch to the
center line of the next synclinal ; each synclinal measur-
ing in breadth from the crest line of one anticlinal across
MOUNTAIN SPURS OF NO. IV. 691
to the crest line of the next. From the very nature of the
curves it is impossible to avoid embarrassment in the use
of these terms ; and it is unfortunate that the double mean-
ing of the terms employed makes their representation to
the mind of the student somewhat vague. If it were pos-
sible to assume points half way down 1he slope we might
confine the term anticlinal to the arch above these lines, and
the term synclinal to the trough below these lines ; but in
practice this cannot be done ; the reader must exercise his
intellect to understand the facts of the case, and keep the
distinction between the upward curves or arches and the
downward curves or troughs as distinctly as possible be-
fore his mind's eye. Nothing in geology is simple ; noth-
ing in any branch of science is easy ; to understand the
true nature of the commonest fact of the world requires a
strenuous endeavor of the judgment and the imagination
working harmoniously together. And this is especially
true in geology, most of its facts being concealed from the
naked eye, and therefore to be mentally conceived, and
cautiously reasoned upon.
Illustrations of the complicated character of the anti-
clinals and synclinals of No. IV are given in fig. 1, pi. LX XIII,
p. 624, and fig. 1, pi. XC, p. 660. See also pi. XCV, XCVI,
XC VII, p. 670. One of these represents a series of sections at
intervals apart of about a mile across the Seven mountains
in eastern Huntingdon county. The other represents a
series of transverse sections, taken at greater intervals
across the main anticlinal of Perry county which crosses
the Susquehanna and runs on eastward between the two
arms of the Schuylkill county anthracite coal basin the
Dauphin basin on the south and the Wiconisco basin on
the north. In the first section the large white band repre-
sents the folds of No. IV, mostly along the plane of the
present surface. In the second section No. IV is every-
where underground, but waved in the same manner ; at
the sections on the Juniata and Susquehanna rivers it is
covered by 10,000' or 15,000' of higher formations.
How is it possible then, it may be asked, to draw cor-
rectly the shape of the waves of the deeply buried forma-
692 GEOLOGICAL SURVEY OF PENNSYLVANIA.
tion. The answer is, that they can be geometrically con-
structed on the supposition that the thickness of the over-
lying formations remain unchanged throughout the region ;
at least that any irregularities of thickness in each will
practically be compensated for in all ; and that the dips
observed at the surface will give a good practical idea of
the basins and arches concealed underground. Nearer than
this to the exact truth the geologist cannot come, unless he
employs boring tools, which is of course not to be thought
of for such great depths. Enough is plainly observable at
the surface to make the complicated structure of middle
Pennsylvania completely evident. Wherever formation
No. IV comes to the surface in mountain ridges a thousand
feet high, cut through to their bases by rivers exposing the
strata, there the character of the anticlinals of the first order
reveals itself with admirable clearness.
The difference between the anticlinal and the synclinal
Knobs of IV.
D. The fourth question must now be answered ; why
the opposite points of a series of zigzag mountains of No.
IV are so totally different in shape and character?
It must be remembered that zigzags of No. IV are pro-
duced only in districts where the plicated formation is de-
scending beneath the surface eastward and consequently
rising into bhe air westward or vice versa. If now we im-
agine such a set of zigzags pulled out to a straight line
in other words, the formation not waved, but still descend-
ing underground in one direction and rising into the air
in the other it is evident that in the descending direc-
tion, it will be first thinly veneered and then more and
more thickly covered with the next soft red shale forma-
tion No. V. In the other direction the bare sand -rock
edges will be abruptly broken off in a line of cliffs, from un-
derneath which will crop out the soft dark shales of No. Ill,
making a steep slope from the foot of the cliffs down to the
floor of the valley ; and in the valley will crop out the
limestones of No! II.
Let us now restore the zigzags. The only difference will
ANTICLINAL AND SYNCLINAL KNOBS OF IV. 693
be, that instead of a long straight range of cliffs at the
crest of the mountain there will be as many pointed pro-
jections as there are zigzags, each projection being a peak
of cliffs, around which the slope of underlying slate will
bend. Between the peaks, and running up into the zigzags,
will be long narrow vales of slate, No. III.
By merely looking from a distance at the shape of the
eastern and western ends of a zigzag mountain of IV a
geologist can tell with certainty in which direction the an-
ticlinals which make the zigzags are dying down, whether
eastward or westward ; for if the anticlinal is rising west-
ward and descending eastward, the east end of the mount-
ains must be a long and gentle slope covered with the red
shale of V ; and the west end of the mountain must be a
high peak, rocky and precipitious, with a steep slope of
slate No. Ill into a valley of limestone No. II. The geolo-
gical county maps furnish plenty of examples of both
kinds ; that is cases where the rocky point is at the west
end and the red shale slope at the east end of the mountain;
and cases where the rocky point is at the east end and the
red shale slope at the west end of the mountain. To assist
the reader some prominent examples may be pointed out.
Taking the southern outcropof No. IV, and following it
from the Delaware Water Gap west ward, Off set knob appears
as a synclinal cliff-tipped projection looking east, while the
red shale end of the zigzag sloping to the west is behind the
Wind Gap. The zigzags.'of the little Schuylkill in northern
Berks are produced by ten small anticlinals sinking west-
ward ; consequently it is the eastern points of the zigzags
which have the Knob cliffs. In Cumberland county the two
projections of the North mountain into the Great Val-
ley are towards the west ; their corresponding red shale
zigzags pointing east are in Perry county. Parnell's knob
and Jordan's knob are similar synclinal end cliffs pointing
southward. The mountains of No. IV in Perry county,
all end northeastward in long slopes of red shale ; their
southwestern ends, projecting into Franklin county, are
high and rocky. The triple central anticlinal group of No.
IV, in Shade, Blue and Black Log mountains die down at
694 GEOLOGICAL SURVEY OF PENNSYLVANIA.
both erids^ eastward and westward, in long red shale slopes.
So does Jack's mountain at its southwest end in Hunting-
don county, and its northeast end in Snyder county. The
Buffalo. White Deer mountains slope their east ends be-
neath the red shale country of Union county, but project
westward into Kishicoquillis, Penn's, Brush and Nittany
valleys in long high rocky ridges, with ranges of cliffs on
each side and broken off sharply at their western end.*
Let us take the case of the west end of the Nittany
mountain in Centre county. Thousands of years ago the
mountain did not end where it now does, but extended fur-
ther west; and ages before that old time it extended still fur-
ther west, indeed all the way to the Juniata river. In fact,
Nittany mountain at that time extended to and was merely
an extension of Canoe mountain in Blair county. In like
manner Brush mountain once extended westward and
united with Tussey mountain. Short mountain once ran
past Aaronburg, Millheim and Spring Mills to join Tussey
mountain, and Egg hill was part of it. The same is true of
the two beautiful mountains which project westward into
Kishacoquillis valley. There was once a time when the
northern knob was extended to meet the Standing Stone
mountain atMilroy ; and the southern knob continued on
through the center line of the valley towards Reedsville.
The proper way to express the fact, then, is to say that
the cliff knobs of No. IV show how far the destruction of
the formation by sunshine, frost and rain in the synclinals
up to the present time has gone. In each instance a rocky
knob marks the exact center line of a synclinal basin ascend-
ing into the air ; and on the other hand every long sloping
red shale nose of a mountain of No. IV marks the. exact
center line of an anticlinal arch descending into the under-
ground. With this clue in hand the student of our geology
*The term broken off, is that which an artist would use, or a mere topo-
grapher, or railroad engineer ; but the student of geology ought not to use
it if he can find any substitute for it ; for there is no geological break at the
ends of these craggy mountains. Let this be well remembered and under-
stood, for otherwise the most important geological idea of this subject will
be lost
CRESTS, SINGLE AND DOUBLE. 695
cnn find his way through the hilly labyrinth of middle
Pennsylvania.
The elaboration of this subject has been intentionally
carried to an unusual length and minuteness in the foregoing
pages, because the laws of Structure and Erosion, expressed
on so grand a scale by the outcrops of IV, hold good in the
million details of structure and erosion on a smaller, and
on the smallest scale, in all the other Palaeozoic formations,
whether regarded in mass, in groups of strata, or in one
single layer. Therefore further allusion to the subject will
not be necessary in other parts of this book beyond occa-
sional references to what has been written in this chapter.
Crests, single and double.
E. The fifth question to be answered, namely : Why
the southern mountains of No. IV have a single crest and
two slopes, while the northern mountains of IV have but
one crest and a terrace, and the northernmost of all, the
Bald Eagle, two crests and no terrace, can be easily an-
swered by merely pointing to the fact, stated in the last
chapter, that Formation No. IV is practically a single sheet
of sandrock at the southern side of the district, and a
double sheet of sandrock at the northern side of it. To state
the fact more precisely : In the Kittatinny mountain facing
the Great Valley the Onieda conglomerate, the bottom
member of No. IV, is coarser, and more massive, and has
resisted erosion best ; while the Medina strata are not only
comparatively thin, but are weakened in their resistance to
erosion by large intervals of softer rocks ; so that the whole
northern slope has been worn down by the weather without
leaving any very bold terraces. In Perry, Fulton and
Franklin counties the Oneida is thin and has a mass of
harder massive rocks above it which make the top of the
mountain, with a pretty regular slope, showing slight in-
dications of terraces. But in the middle and northern
groups of mountains of IV the formation consists of very
massive Oneida at the bottom, and still more massive
Medina at the top, the two separated by a thick, soft, red
mass. The Medina therefore makes the crest of the mount-
696 GEOLOGICAL SURVEY OF PENNSYLVANIA.
ain, protected by the softer but still pretty massive middle
division; while the Oneida, undermined by the soft sin re
ormation of No. Ill on which it rests, unable to rival the
Medina in its resistance to the weather, and therefore in its
height, is necessarily left as a bold terrace on the outcrop
slope, about two-thirds as high as the crest of the mount-
ain. In the majority of cases the dip of the formation as
a whole, whether toward the south or toward the north,
ranges between 40 and 60 ; so that the Medina upper
slants upward through the mountain as its central rib or
plate from base to crest, its cliffs overhanging the terrace
of Oneida below.
Difference in tlie height of mountains of IV.
F. The sixth point of topographical interest to be ex-
plained geologically is the fact of the Bald Eagle mountain
having two crests of equal height and no terrace ; and the
additional fact that this mountain with two crests is in-
ferior in height to the opposite Tussey mountain, which has
but one crest and a terrace.
In Tussey mountain the upper Medina is thick and the
Oneida thin ; whereas in Bald Eagle mountain the upp^r
Medina and the Oneida are of about equal thickness. In
Tussey mountain therefore the upper Medina makes a
high crest and the Oneida a terrace ; whereas in Bald
Eagle mountain each makes a separate crest.
The inferior height of the Bald Eagle mountain is due to
the fact that its stratification is vertical.
This leads us to the consideration of another law of topo-
graphy, namely that (other things being equal) the relative
heights of mountains is determined by the angle at which
their rocks lie to the horizon ; the flatten the rocks the
higher the mountain; the steeper the dip the lower the
mountain ; the steepest dip (90) makes the lowest mount-
ain.
Surface erosion, that is, the gradual destruction of
strata at their outcrops, comes about as a double process
of undermining, and toppling down. However hard and
massive a formation may be, and therefore in itself consti-
KEEL MOUNTAINS OF IV. 697
tuted to resist erosion, its powers of resistance will not avail
it, if it lies, at a moderate slope, upon a soft, easily weather-
ing formation underneath. For, as the underlying softer
rocks are removed by the weather, the overlying, massive,
hard rocks tumble down in blocks separated by the cleavage
planes. But if the underlying softer formation has in it
numerous interstratih'ed beds of hard rock, its own rate of
erosion is made slower thereby, and the overlying forma-
tion is less rapidly undermined ; consequently its height
above the valleys remains always relatively greater.
But when the stratification is vertical, a lower massive
formation (like the Oneida) can no longer give a protective
support to an upper massive formation (like the upper Me-
dina}. Each must take care of itself separately. It is a
case of "divide and conquer." The sunshine, frost and
rain have the mountain at a disadvantage, and reduce its
relative height to a secondary rank. This interesting law
of erosion illustrates itself by producing various features
of topography which are inexplicable to minds not familiar
with the character of the war which is perpetually waged
between the attacking and defending parties, the elements
of erosion on the one side, and the rock constituents on the
other.
One beautiful illustration of the way in which the rocks
support each other against the assault of the weather may
be found in the synclinal knobs ; for, in these knobs two
outcrops come together and are therefore united in self-de-
fense. In addition to their union they lie horizontally
along the center line of the basin. The anticlinal knobs
are still better protected, and are therefore relatively higher
than the synclinal knobs, as shown in the sketch of Tussey
mountain as seen from the top of Terrace mountain, back of
Stonerstown, in Huntingdon county (Fig. 42, p. 143, of
Manual of Coal).
Keel mountains of IV.
Before leaving the subject of the crests and terraces of
No. IV, the most beautiful phenomenon in the topography
of middle Pennsylvania must be mentioned. When two
GEOLOGICAL SURVEY OF PENNSYLVANIA
crests converge and become one. projecting as a single
high narrow ridge, between two limestone vales, and end-
ing in a synclinal point, their two terraces curve and unite
around the end of the point.. If the curve be a semi-circle,
that shows that the synclinal is rising rapidly into the air.
But if the synclinal rises very slowly the combined terraces
project miles beyond the end of the crest, and then come
to a similar, but lower synclinal point of their own in the
limestone valley. This is the case with the two synclinal
terraced mountains at the east end of Kishicoquillis valley;
and it is the case with Short mountain, Brush mountain
and Nittany mountain in Clinton and Centre counties. A
spectator regarding these mountains from the floor of the
valley, sees them end on in perspective, or as if in section,
arid is struck with surprise at their symmetrical shape, re-
sembling ships that have been turned over with their keels
uppermost (Figs. ). For this reason they received from
the geologists of the First Survey the name of Keel mount-
ains of IV.
Ravine system of IV.
Gr. The seventh and last item of topographical interest
relates to the two entirely different modes in which the
two sides of a terraced mountain of IV is drained. Tussey
mountain, for example, with rocks dipping south into
Huntingdon county, and outcrops overlooking northward
the great limestone valley in Centre. On the Huntingdon
side there is a long slope of the red rocks of formation No.
V, down which the rainfall delivers itself by innumerable
rivulets, flowing in straight and shallow channels from crest
to base. On the other or Centre county side the uppermost
slope next the crest is a sheet of fallen fragments of upper
Medina, stopped in their descent by the Oneida terrace, the
rainfall cannot deliver its waters in straight lines to the base of
the mountain on account of the massive Oneida strata which
out-crop along the brow of the terrace. Consequently it cuts
deep ravines sideways, right and left, in the soft lower Me-
dina ; and these ravines meeting in pairs, break out through
the Oneida terrace and its supporting slates of III, in deep
THE ANTICLINAL VAULTS RESTORED. 699
short gorges debouching upon the limestone valley. The
regularity of this system of terrace ravines is wonderful.
The ravines are all alike in depth, narrowness and steepness
of sides. The distance from ravine to ravine is almost ex-
actly the same from one end of the mountain to the other.
Each ravine has a double head, one to the right the other
to the left, its branches being usually of equal length.* It
is impossible to repress one's admiration at this flagrant
proof, first, of the regularity of the mountain constitution ;
secondly, of the equal action of the elements upon it at all
points ; thirdly, at the total absence of violent, paroxysmal or
irregular conduct in the processes of nature. In fact it may
be said, that a student who wishes to investigate the subject
of Erosion, that is, the perpetual destruction of the earth's
surface by the surrounding atmosphere, and the ways in
which this destruction is accomplished, could not do bet-
ter than to start his investigation with a close study of the
terrace ravines of No. IV; for he would tind out in his
subsequent experience that this special physical phenome-
non will suggest the true explanation of every detail of the
features of an eroded region.
The Anticlinal vaults restored.
It only remains to say, that when one has familiarized him-
self with a limestone valley shut in between two mountains
of IV, with their even rocky crests, and ravine cut ter-
races, the strata dipping always away from the valley in
both directions, he cannot hesitate to drawing the conclu-
sion, that as the two mountains come together at the two
* See also the map of the south flank of Jack's mountain in Mifflin county,
given on page plates CIV, CV, CVI, CVII in the next volume. These
plates present (on a scale of |) the eastern half of the unpublished MS. map of
the south flank of foot hills of Jack's mountain from Logan's Gap west to
McVeytown. The map stretches westward to Mount Union and Jack's
Narrows, exhibiting similar features. It was one of the earliest pieces of
topographical work of the Survey (1874-75), and was intended to illustrate
Report F on the fossil ore belts of the Lewistown valley, but was not finished
in time for the publication ot that Report. It is now used as an illustration
in the chapters on the Clinton formation, No. V. The terrace ravines are
shown in fig. 2, plate XIV, p. 376 ; in plate XVII, p. 389; plate XXII, p.
400 ; and especially by the great map sheets of Morrison's Cove, in Report
T, Atlas.
700
MODEL OF PLICATIONS OF IV.
ANTICLINAL VAULTS RESTORED. 701
ends of the valley, so their strata were formerly united in
the air above in an immense arch or vault of unbroken sand-
stone miles high.
This effect upon the judgment and imagination com-
bined is irresistible in the case of the larger valleys. In
the case of a long and narrow anticlinal valley like Black
Log, a casual visitor might not be led to this conclusion,
but to a very different one. His first impression would
probably be that the strip of limestone land along the center
line of the valley had been pushed up, splintering asunder
the overlying slate and sandstone formations (III and IV),
and thrusting the broken edges of the fracture to the right
and left. In the beginning of the present century such was
the theory of the Swiss geologists, Thurman, Desor, and
others, respecting the valley formations of the Jura ; and
such was the theory respecting all the mountains of the
world entertained by one of the fathers of German geology,
Leopold Yon Buch. Quite recently has this old and false
conception ceased to mingle intimately with correcter views
in many minds. The principles enunciated in this chapter
nevertheless cannot be called new, for they were fully ex-
plained and sufficiently illustrated in my "Manual of Coal
and its Topography," published in 1856, and in Professor
Rogers' Geology of Pennsylvania published in 1858. But
even then they were not new ; for the whole subject of Pli-
cation and Erosion was placed permanently on its proper
basis of demonstrated theory fifty years ago, by the assis-
tant geologists of the First Survey of Pennsylvania ; and
both facts and principles were known and used by Whelp-
ley, Henderson, Jackson and McKinley in their daily field
work, and in the construction of the maps and sections with
which they illustrated and embellished their reports. It has
been recently stated as a new discovery that there is an or-
ganic connection between anticlinal folds and down-throw
and up-throw faults ; and the credit of this supposed dis-
covery has been given to the able geologists of the United
States Survey in the Rocky mountain regions. But like
other applications of principle to fact in this whole sub-
ject, the passage of arches into f units was so fally explained
MODEL OF PLICATIONS OF XO. IV.
THE ANTICLINAL VAULTS RESTORED. 703
by the early surveys of Pennsylvania and Virginia that
nothing essentially new or different has in recent years been
added to it, except in the one point of the distance to
which Onerthrust faults have been carried horizontally, as
in Western Scotland, the Alps, and the Rocky mountains.
Model of the upper surface of the Medina, No. IV, after
its plication and before its erosion.
Page plates LVII, LVIII were made from two photo-
graphs of the surface of a model constructed by me in 1886,
to show the crumpled geology of Middle Pennsylvania, as
contrasted with the gently waved structure of the whole
country back of the Allegheny mountain (the western and
the northern counties) and the almost wholly undisturbed
condition of things in the Pocono and Catskill mountain
region on both sides of the upper Delaware river.*
*I planned this model In 1841 while I was drawing the thirteen long sec-
tions across the State which Prof. H. D. Rogers published in 1858 along
the bottom border of my State Map. But the data obtained by the First
Survey did not seem to me sufficiently precise. When the Second Survey
was organized in 1874 I waited until the surveys of the middle counties could
be mapped, with local sections abundant enough to cover the whole area. By
1886 most of the county maps had been published on a scale of two miles to
the inch, with well-defined limits to the formations. In 1885 1 published, in
Report X, count3 r maps of the whole State on the scale of six miles to an
inch. Of these I selected enough to cover a sufficient area, and afford a sat-
isfactory basis for a model.
There are but two methods of making such a model ; one is to cut it down
to fixed limits ; the other is to build it up from a base plane. With hypso-
metrically surveyed contour line maps of the surface the simplest method
is to jig out the contours in paper, card board, or veneer wood ; pile them on
one another ; paste, glue or tack them fast ; cover them with wax ; tool the
whole to a smooth surface ; cast a mold ; from the mold cast a positive ; and
finally tool it to satisfaction. In 1856 I made such a model of the Johnstown
district in Cambria and Somerset counties, from Edward Smith's contour
map of the country for the Pennsylvania railroad. Sheets of paper repre-
senting Smith's 10-foot contours were scissored by myself and my wife in
the evenings, and the result was a very beautiful model, the photograph of
which was made into a relief plate and published in 1877 in Report H2, page
92. But it was a tedious and laborious job.
Most of the models of the Second Survey have been made in this manner,
chiefly by Mr. E. B. Harden, topographical assistant of the survey. The
process requires nothing but accurate, patient labor.
Another method is to construct cross sections at various intervals across
the area to be modeled, and as nearly as possible at right angles to the
704 GEOLOGICAL SURVEY OF PENNSYLVANIA.
The model is limited on the south by the Maryland and
YV. Virginia state line, from Adams county to Fayette
county ; on the southeast by the range of the South mount-
ains, the Reading and Durham hills, and the Highlands of
New Jersey and New York : its lower left hand corner is
strike ; draw them on slips of paper, wood, lead, zinc, or block tin ; leave
the bases of the strips straight cut the upper section surface lines ; arrange
the strips on a solid basis at their true geographical distances from one an-
other ; nil in the intervals with plaster or wax ; and tool the whole model
to the upper section lines. This, however, requires the eye and hand of an
artist ; but it has the advantage of a more delicate and truthful treatment of
the intervals between the section slips, governed and guided by the topo-
graphical features of the survey map of the region modeled. The geological
artisst is not encumbered with the solid plates of the first method, and can
work freely in correcting and bringing out to clear view the characteristic fea-
tures of the topography, provided he has studied them himself and appre-
ciates their character. This method can safely be adopted only by the geolo-
gist who has done the field work himself, and it cannot be safely delegated
to office hands.
I used a modification of this process for a model of Morrison's Cove, in
1853, for the Pennsylvania Railroad Company, to show the iron ore horizons.
I took prisms of soft wood 18" long, 3" wide and 2" thick, and drew on their
contiguous sides duplicate geological sections ; then tooled down the surface
of each block. When laid side by side in a series, the surface of the country
was exhibited topographically. By separating the blocks the geological
structure on the cross lines between block and block could be consulted.
The surface of the whole series was painted to show the outcrop belts.
In constructing other local geological models I have found this method
much more satisfactory than the method of jigging and building up.
But in making my model of the corrugations of middle Pennsylvania I
was compelled to use the method first described, on account of its rapidity
of execution, since I accomplished in six weeks what would probably have
cost me as many months of labor by the method of cross sections. A descrip-
tion of the details will be useful to geologists who are not familiar with
such work.
I first laid the colored geological Hand Atlas county maps together to
cover the field. I divided the field into four parts by equal N. W. interval
lines to make four models which could afterwards be cast in one. Then I
drew on tracing paper the outcrop limits of the formations above and below
the Medina. The known thickness of the overlying formations gave the
depth of the top of Medina in reference to sea level. Sea level was the nor-
mal datum of the model. The deepest sea level of the top of the Medina was
adopted as the plane base of the model. The contour lines of the top of the
Medina were determined by measuring down from the contour limit lines
of all the upper formations. Account had to be taken of the known thin-
ning of all the formations northwards and westwards. The columnar sec-
tions governed the whole process. When the dips were steeper a reduction
for angle had to be made. When the dips were gentle, no such reduction
was necessary, as the error would be trivial. In the end I obtained an un-
UPPER SURFACE OF MEDINA, NO. IV. 705
in Butler county. The area exhibited is about 230 miles
long by 130 broad. The scale adopted was that of the
small county maps in the Hand Atlas, Report X, 6 miles to
the inch. The photograph plates reduce the scale to about
33 miles to the inch.
It was essential to my design of a true representation of
the amount of plication that the vertical scale of relief
should be the same as the horizontal geographical scale, a
principle which has been kept in view in the construction
of all cross sections published in the Reports of the Survey
from the beginning. No matter how gentle the gradients
they must conform to nature. The human eye is a perfectly
competent instrument and may be safely trusted to notice
and estimate accidents of relief of the minutest size and
most delicate variation from the horizontal. Nothing
should be left to the imagination. Science gains nothing
and loses much by any exaggeration under any circum-
stances. There is no such thing as meeting nature half-
way. Absolute truth in relationships is as necessary for
knowledge as correct understanding of individual things.
For plate .L/VII the model was photographed upside
down, with a slant light from the left (S. E.) to bring out
the master feature of the structure, the Nittany Valley or
Bald Eagle Mountain Anticlinal, which occupies in crescent
shape the center of the area. As its western slope is very
steep, in parts vertical, the shadow cast is heavy. The
prevalence of steeper western than eastern slopes in the
case of most of the other anticlinals is marked on this
plate ; especially in the case of the three great anticlinals
which lap each other and make the southern border of the
First Anthracite coal field from Mauch Chunk, Tamaqua
and Pottsville to the end of the Dauphin county basin, and
so onwards through Perry and Cumberland county into
Franklin. The echelon arrangement of this combined over-
derground contour line map of the top of the Medina approximately correct.
It was only necessary afterwards to take the curves of dip in the air to re-
store the aticlinals destroyed by erosion, and the model was complete. The
scale being 6 miles to the inch horizontal and vertical alike, an inch of height
represents 31,680 feet.
45
706 GEOLOGICAL SURVEY OF PENNSYLVANIA.
thrown anticlinal is very remarkable and could be well ex-
hibited only by a model seen under a S. E. slant light.
For Plate LVIII the model was photographed erect under
a slant light from the left (N. W.) to bring out other fea-
tures ; especially the Anthracite synclinals and their con-
tinuation southwestward into Maryland. The reader will
notice that from Carbondale (an inch below the center of
the top line of the plate) there is a continuous synclinal
trough, much crumpled in the center of the plate (Seven
Mountains), with a local deep hole (Broad Top), shallowing
into Maryland. It will be noticed that the Nescopec anti-
clinal of Luzerne county, which separates the Middle and
Northern Anthracite basins, keeps on as the anticlinal of
Kishicoquillis valley and Jack's mountain, dying down in
Bedford county.
The crescent shape of the corrugations of the region is
visibly explained by Plate LVII, which brings into relief
the great Nittany anticlinal. By taking its crescent as an
arc of a great circle, and drawing a radius from its middle
and highest point (in Centre county), southeastward towards
the head of Chesapeake bay, it will be made evident that
along that radius was exerted the maximum force of the
horizontal thrust which displaced the formations and piled
them together in folds. By laying a string upon the model
along this radial line, I found that the forward thrust of
the earth crust (so far as the Medina can indicate it) was at
least 40 miles. It is worth noting also that the Bald Eagle
Mountain and Black Log Mountain faults are southwest of
said radius, and have their right hand (N. E.) side walls
thrust forward.
Conformity of IV upon 111. \
1 have expressed my opinion on this interesting geolog-
ical topic in the third report on Lehigh and Northampton
Counties, D3, Vol. 1, 1883, pp. 32 to 35.
A non-conformity of the Oneida conglomerate, No. IVa,
upon the top of the Hudson river slates, No. Ill, has fre-
quently been asserted. In Pennsylvania they appear to be
quite conformable ; no erosion of the uppermost slates of
CONFORMITY OF IV UPON III. 707
III previous to the deposit of the conglomerates and sand-
stones of IV having been noticed.
At the Rondout quarries in New York the Helderberg
limestones seem to lie upon the upturned edges of the Hud-
son river slate. At Catskill village they appear to lie di-
rectly but conformably upon the slate.
Mr. Davis in his recent beautiful memoir (quoted in G 6 )
states in his text and shows in his sections an apparently
perfect conformdbility of the Lower Helderberg limestones
(JVo. VI) upon Hudson river sandstones and slates (No.
Ill] in the vale of the Catskill, a mile or two back from the
Hudson river; with an apparent absence of the Clinton ( V)
and Medina and Oneida (IV) which usually intervene.
Although the district of country in which these phenom-
ena present themselves is small, yet, out of these local phe-
nomena an hypothesis has been framed and made to apply
to a thousand miles of the continent, viz : that the Hudson
river age closed not merely with a disturbance of the re-
lations of land to sea, resulting in the shifting of coasts and
the deposit of gravels and sands (which might be easily
admitted), but with huge elevations and upturnings of the
sea-bed, extensive erosion, and the deposit of horizontal
upon vertical strata.*
* S. A. Miller in his N. A. Geol. and Pal. 1889, p. 48, says : It always rests
unconformably upon the Hudson river group, and bears the internal evi-
dence of having been derived from land immediately north and east, and of
having been deposited in shallow water, subject to waves and currents which
transported only short distances. The conglomerate indicates a shore-line
and rapid deposition, and is almost non-fossiliferous, although a few frag-
ments of fucoids and shells, generally too imperfect for definition, ba^e been
found in it The sandstone too bears the evidence of having been deposited
near the land in shallow water, not only in wave-lines, rill-marks about
shells, and ripple-marked slabs, but in mud-cracks produced by sun-drying.
In all these respects it compares with the Potsdam, which separates the Ta-
conicfrom the Lower Silurian."
Certainly a sand deposit that extended from May Hill in England to Lake
Huron and Tennessee in America, must exhibit the character of a shore de-
posit in some places, but could not possibly have done so everywhere. Cer-
tainly in its many hundreds of miles of outcrop in Pennsylvania itshows noth-
ing of that character. The fine grain of almost all of the sandstone layers of
its upper and lower divisions and the loamy nature of its whole middle di-
vision, is satisfactorily good evidence that the great Medina sea was not
shallow, but deep ; and the pebbles of its conglomerate beds are so small
708 GEOLOGICAL SURVEY OF PENNSYLVANIA.
To this I object : 1. the almost universal conformability
of the Oneida upon Hudson river formation ; 2. the ab-
sence of pre-oneida plications; 3. the impossibility of ob-
taining the principal materials of the Oneida conglomerate,
out of any known Hudson river strata ; 4. the fact that
Oneida deposits still remain far south of the Hudson river
belts (as at Greenwood lake in New Jersey) ; 5. and above
all, the fact that at the Schuylkill Water Gap, where the
Oneida rests at right angles on the apparently eroded edges
of Hudson river slate, there is in reality a snapped anticli-
nal and downthrow of the slates, and no unconformability.
Mr. Davis shows the Lower Helderberg conformably over-
lying the Hudson rioer "sandstones," in a synclinal.
At first glance this would seem to settle the question of
land elevation and subsequent subsidence ; and he there-
fore speaks of a long interval of time (Oneida, Medina and
Clinton ages) during which no deposits took place.
But a little consideration will serve to show the uncer-
tainty of this kind of evidence. For, during all these ages
it no doubt rained as often as it rains now ; and if so, all
land surfaces must have suffered erosion ; and yet the Hud-
son river slates in his Catskill section are not eroded ; they
could not therefore have been rained on i. <?., they could not
have been above water.
The alternative is 10 imagine a stoppage of deposit with,
out elevation of sea bottom. This is not impossible, but very
improbable. For, the Oneida was heavily deposited a few
that they could be carried out some hundreds of miles from shore, as De-
lesse has shown the pebbles of the Loire are now slowly worked along out-
ward over the sloping bed of the Bay'of Biscay into the deep Atlantic.
The assertion that it " always rests unconformably on the Hudson river
group is unwarranted; because not the thousandth part of the formation
is visible at the surface; and because, as 1 state in the text, an examina-
tion of many hundreds of miles of outcrop contact of III and I Vat the pres-
ent surface has shown not non-conformability but conformability. The
"Water Gaps of middle Pennsylvania furnish abundant evidence of the fact.
A very good evidence of deep sea deposition is the almost total absence of
oblique-bedding in IV, showing that its sands and muds were not subject to
the tidal currents of shore deposits and shallow water. In this respect it is
in marked contrast with the Pocono formation No. X, which contains the
Tipton Run coal beds and was a shallow water deposit, as will appear in a
future chapter.
CONFORMITY OF IV UPON III. 709
miles west of Newburg. and from there on for hundreds of
miles westward and southwestward.
An easier hypothesis would be to consider the " Hudson
river sandstones" which lie beneath the limestones, to be a
finer part of the same deposit as the Oneida and Medina
conglomerates and sandstones elsewhere.
But there is another alternative, in view of the close
proximity of vertical and overturned strata between the
quarry and the banks of the Hudson. The crumpling which
Mr. Davis so eloquently describes and so artistically por-
trays has been produced by the sliding down upon itself
and mashing together of the still moist formations on the
western slope of the Hudson river uplift. Precisely simi-
lar crumplings characterize the same limestones all along
the north foot of the Medina-Oneida mountain range
through New York, New Jersey and Pennsylvania. And
it is in front of these crumplings at the Schuylkill water
gap that the great fault occurs which plunges the edges of
the slates underneath the bottom of the conglomerate.
It should be kept in mind that our massive formations
(XII, X, IV) act independently of the softer formations be-
tween them, preserving their own larger plications intact
and for themselves, and compelling subjacent and super-
jacent formations of inferior tenacity and greater ductility
to conform to limited spaces by crumpling and sliding. It
is quite possible that the faulted edges of the missing rocks
may lie deeply buried. At all events, such is not so violent
an hypothesis as that the Hudson river slates remained two
or three geological ages out of water without suffering the
least erosion.
Non-conformity of IV upon III has been argued from the
presence of pieces of shale in IV. But there are also dis-
tinct bands of intercalated slate between the sandstones.
Even supposing fragments of foreign slate, they could not
come from neighboring Hudson river outcrops. For, if the
Oneida was deposited over the whole region of Northern
New Jersey as far south as Greenwood lake, how could any
shore produced by an upheaval at the close of the Hudson
River age be near enough to furnish such materials as
710 GEOLOGICAL SURVEY OF PENNSYLVANIA.
those of which the Oneida is composed ; and how could
"'pieces of Hudson river slate" get into the Oneida?
But the most complete evidence that there was no change
in the relations'of land to water at the top of the slate for-
mation No. Ill, and before the deposit of the great sand-
rocks of No. IY, comes from the shape of the Kittatinny
mountain along its whole line from the Delaware water gap,
past the Lehigh water gap, to the Berks county corner, and
far beyond. Any erosion of the slate formation previous
to the deposit of the Oneida sandstone beds would have
made the outcrop of the Oneida beds very irregular. It is
on the contrary remarkably regular ; and the synclinal
sandstone crest in Offset mountain, just east of the Wind
Gap, lies quietly in a synclinal of slate ; all the rocks dip-
ping in conformity. Any slight difference in angle re-
corded in the Water Gaps between the sandstone beds
above and the slate beds on which they rest must be due
either to imperfect instrumentation ; or to the concealment
of the actual plane of contact ; or to the inevitable slip of
the upper rigid mass on the lower flexible mass in the pro-
cess of uplifting the whole 30 or 40 from the horizontal.
When this uplifting reached 90 at the Schuylkill water gap,
a great fracture took place, and the whole sandstone mass
shot upright into the air, grinding the edges of the slate
mass, which remained nearly horizontal, to a smooth plane.*
Along the whole range of mountain in Northampton and
Lehigh counties, the upper limit of the slates rises to the
top of the long slope, to within about 200 feet of the actual
crest of the mountain, where the cliffs of Oneida commence.
* At the Lehigh Water Gap, on the east bank of the river, near the railroad
bridge over the wagon road, massive conglomerate strata at the base of IV,
ascend at an angle of 30 to the crest of the mountain. This conglomerate
consists of white and black pebbles an inch in diameter. Fine grained
sandstone beds ^overlie and underlie the conglomerate. Fifty feet lower
than the conglomerate the rocks are concealed for 50 feet, and then under-
lying sandy slates appear gradually, passing downward into the top slates
of ill, which soon after turn over an anticlinal and dip south. It looks as
if the concealed interval is the plane of a fault, and the north dipping slates
a downward brush. But there is no proof of non-conformability, and it is
quite possible that the anticlinal arch is unbroken, just as in the case of the
anticlinal behind the Hole mountain at the Swatara Water Gap.
CONFORMITY OF IV UPON III. 711
Downwards the mountain slope dies away in the slate plain,
chiseled by a thousand brooks which collect the rain water
and continue the operation of lowering gradually the gen-
eral level of the slate belt.
712 GEOLOGICAL SURVEY OF PENNSYLVANIA.
CHAPTER LIU.
Tfte mineral worthies sness of the North Mountain along
the Great Valley and of all the other mountains of IV
in Middle Pennsylvania.
This is a fixed fact. There is not a valuable mineral of
any kind in the Oneida or Medina formations.
In the mountains of IV there is nothing but worthless
slate and common coarse and fine sandstones, the outcrops
of which make the crest and back slope of the mountains,
and the great ribs of rock in the gaps where the rivers break
through. Some of the layers yield excellent building stone ;
but building stone is a drug in the market in Pennsyl-
vania. Almost every citizen of the state can build a stone
house or barn by digging a hole on his own farm ; so that
what is valuable to himself is of no value to his neighbors,
much less to commence. The limestone of the valley is a
better building material than the sandstone of the mount-
ain, and more easily t obtained ; therefore the sandstone
rocks may be said to be worthless. Occasionally a piece is
wanted for the hearth of an iron furnace.
There is no gold,f no silver,:}: no copper, no lead, no tin
fTLie latest deception respecting a gold mine in No. IV occurred two
years ago in the neighborhood of Jack's Narrows in Huntingdon county,
where a company was formed to mine gold in Jack's Mountain west of
the Juniata river at Mapleton. What gave rise to it I do not know, but it is
probable that a trace of gold was found in some pebbles in the conglomerate,
such as is described in the geology of the Schwangunk Mountain in New
Jersey. All quartz seems to have a trace of gold in it. But gold-bearing
quartz veins have no existence in the mountains of No. IV.
} Nothing can be >more ridiculous than the report of silver veins in any
mountain of IV. As gold goes with quartz silver goes with limestone. If
there were faults filled with lead ore in the Medina Mountains more or less
silver, if only a trace, would be found in the lead ore. But no lead ore vein is
known in Pennsylvania in any of its mountains of IV. The lead ore is con-
fined to the limestone valleys.
The remarkable cross fault lead veins of [the Schwangunk Mountain of
IV east of the Delaware have already been noticed. None such have been
MINERAL WORTHLESSNESS OF MOUNTAINS OF IV. 713
in these mountains. All the old Indian stories about lead
ore, and all the lying assurances of wandering miners that
they have discovered gold and silver ores in the mountain
amount to nothing at all.
As for iron ore the only show of it is in the slates just
under the sandstone near the summit. These top slates con-
tain enough iron to coat the stones, and to make little iron
ore bogs lower down the slope where the springs of water
issue. The iron-coated sandstones are of course worthless.
The bog ore is good enough, what little there is of it, and
mixes nicely with other ores ; but the farm clearings where
these bogs lie can hardly be said to be a dollar more valuable
for them. There is no iron ore bed which could be found
by searching for it. The iron is distributed through the
slate and cannot be mined.*
On the backside of the mountains of IV run outcrops of
the valuable iron ore beds of the Clinton formation No. V,
noticed in that mountain from Port Jervis westward in New Jersey, nor in
any mountain of IV in Pennsylvania. When I was surveying the Strouds-
burg country in 1839, I learned that a geological tramp from Germany had
been deluding the people into preposterous mining operations in the
Pocono Mountain. There were traditions of sixteen different Indian silver
ore veins in the Kittatinny Mountain east and west of the Wind Gap. This
impostor told the people that he had found one of these veins, had traced it
across the Aquanchicola Creek valley, across Godfrey's ridge, across Broad-
head's creek near Stroudsburg, across the Devonian hills to the foot of the
Pocono Mountain escarpment and up the escarpment to a place where it
could be successfully mined. He collected one or two thousand dollars in
small sums from the farmers and village storekeepers, and kept him-
self and one or two hands at work for eighteen months making a large hole
in the face of the mountain, and then disappeared leaving the hole behind
him. Such is a history of fraud many times repeated in the last fifty years.
* One remarkable exception to this statement must be noticed. There is
a gash fault across Black Log Mountain west of Orbisonia in Huntingdon
county, which was filled with limonite iron ore long before the mountain
and valley surface of that country was established at the present level.
Nothing of that sort escapes the keen eye of the hunters and farmers of any
region. The search for iron ore keeps men and boys on the qui vive ; and
this curious and exceptional deposit was exploited by furnace men and ex-
hausted. No other such instance is known in our state, and probably no
other exists. It is strictly analogous to the lead veins of the Schawngunk
Mountain east of Port Jervis ; for the Black Log Mountain is shivered by
cross faults in the same manner ; as exhibited in the Rock Hill Gap and in
the gangways of the fossil ore mine southwest of Orbisonia.
714 GEOLOGICAL SURVEY OF PENNSYLVANIA.
block ore aud fossil ore. These beds have been foun dand
opened here and there along the North Mountain, but with-
out financial success. In 1839 I discovered the block ore
just behind the mountain on the bank of the Little Schuyl-
kiJl opposite Port Clinton. Since then the bed has been
opened ; but the attempt to mine it was abandoned ; the ore
was poor and the bed thin. And this appears to be the
case along the whole line for a hundred miles. Back of
Cowan's Gap in Fulton county it was tried. In the Lit-
tle Cove southwest of Mercersburg it is of little value.
But this has nothing to do with the Oneida and Medina.
If any religious mind asks why God made the mountains
of IV without a single valuable mineral in it a question
which has been more than once put to me respecting other
mountains mineralogically worthless the answer is a plain
one and should be satisfactory to any reasonable man.
Mineral value is not the only kind of value. The true worth
of mountain land is to cool the air and condense its mois-
ture into rain, to feed the streams which supply the valleys,
and to preserve the forests. For such benefits as these the
inhabitants of the Great Valley should be ever thankful to
the North Mountain without looking so fine a gift horse
in the mouth or pining for gold or silver mines, which
after all are not half so desirable as fertility and water
power.
FOSSILS OF ONEIDA AND MEDINA NO. IV. 715
CHAPTER LIV.
Fossils of Oneida and Medina No. IV.
The whole formation is remarkably destitute of remains
of animal and vegetable life. The abundance of molluscan
and crustacean forms in the preceding Trenton and Hudson
River ages seem to have given place to a barrenness of all
living existence. Nothing but the stony casts of macerated
seaweeds are to be found in the two or three thousand feet
of rock strata of Oneida and Medina age in Pennsylvania.
These are so abundant in some places as to cover extensive
surfaces of the sandstone beds. Their forms are repre-
sented on plate CXI, page 716. They are most abundant
in the upper division.* This species of seaweed is called
Arthrophycus Tiarlani. The surfaces of great slabs torn
from the Tussey Mountain outcrops on the Juniata and
floated by ice down the bed of the river, are completely
covered with a network of its stony casts in high relief.
In New York State James Hall describes from the mid-
dle division of IV two small lamellibranch shells Cypricar-
dia orthonota, and Modiomorpha alata (Conrad's Unio
primigenius), and two small gasteropod shells, BelleropJion
trilobatus (Conrad's Planorbis trilobatus) and EnompTia-
lus (Cyclostoma, Pleurotomaria} pervetustus. the earliest
known appearance of this kind of shell. Dana says that
one of the most common Medina brachiopod shells is the
*Prof. W. B. Rogers, Geo. Va., 1884, p. 175, says that "near the upper limits
of the group, as well as in the shaly bands beneath, organic impressions are
often abundantly discovered. The thin slabs of buff and olive sandstone
lying near the top are particularly rich in these remains, among which may
be noted as abundant a small globose terebratula, and at least two well
characterized species offucoides [sea weeds]. Cylindrical markings, simi-
lar to those of No. I, are often exhibited in great numbers in the more com-
pact and fine-grained white or pinkish white strata.
716 GEOLOGICAL SURVEY OF PENNSYLVANIA.
HarUnla halll. (Go.pp.rt. Fo. Klor. de. Ueberg, 1.
~
Conrmd. (tic. Trfn/bn in Pa.
Collect*? from /to, at Pert C2w ton;
and front IVi.c, '
Omitted from
"&*nf*fou
* /U/a/At above
<o f
Cypricardla orthonota. Ha/I.
ModiomorphaalaU.atf.
(G/on'(a.tci
alata,
(llnio prhmyfiui
Bellerophon trilobatua M*n*lfa MflaJ
FOSSILS OF ONEIDA AND MEDINA NO. IV. 717
wedge-shaped Lingulella cuneata.* He figures also two
lamellibranch shells Modiolopsis orthonota, and Modiolop-
sis primige/iia, and the two gasterpods Pleurolomaria
litorea, and Bucanella trilobala (Conrad's PlanorMs above
mentioned). He adds that a considerable number of Me-
dina species lived on into Clinton times. In fact the dearth
of Medina life in Pennsylvania was due to peculiar circum-
stances, as the astonishing thickness of the sand deposits
sufficiently attest. In other parts of the earth's waters
there was an abundance of life. For example, the rocks of
this age exposed on the island of Anticosti in the Gulf of
St. Lawrence are crowded with fossil forms. f
The English May Hill sandstone formation, the repre-
sentative of our American Oneida-Medina formation, was
deposited in waters so full of life that 261 species (of 91
genera) have been found in it, 136 species being peculiar to
it. Among them is the oldest known sea urchin, Palceec/ii-
nus phillipsi, Forbes4
The oldest insect recorded up to 1887, Palceollattina
douvillei, was found on a slab of May Hill Sandstone at
Turques in Calvados, France, by C. Brongniart It is one
wing of a cockroach, distinguished from all other known
cockroach wings, fossil or recent, by the length of its anal
vein, and the narrowness of the axillary area.
The abundance of plants and animals of the sea, and the
existence of land beetles being demonstrated, it follows as
a matter of course that the land surfaces sustained a vege-
tation of their own. No remains of land plants have been
found of the definite Medina age ; but a superb fossil fern,
Eopteris morierei, Saporta, has recently been discovered in
* The figure on Plate CXI, from Hall's Pal. X. Y. Vol. IV, shows three of
these little lingulas (lingulellas) stranded on a beach over which the waves
dragged the fine sand into pointed ridges in the wake of the shells. Ripple
marks and mud cracks prove that the beds were out of water and exposed
to the sunshine, and that the sunshine was as genial then as it is now.
t Dana's Manual of Geology, 3d Ed., 1880, p. 223.
+ Figured by him in the early Memoirs of the Geol. Sur. G. Brit., Vol. II,
plate XXIX, p. 674. Desor's Synopsis des Echinides fossiles, 1856, page 159.
Geikie's Text Book, 1882, page 674.
Woodward's paper in Geol. Mag., Feb., 1887, p. 49, quoting ComptesRen-
dus A cad. d. Sci. Paris, No. 29, Dec. 26, 1884.
718 GEOLOGICAL SURVEY OF PENNSYLVANIA.
the schists of Anglers. These schists are placed by French
geologists at or near the base of the Middle Silurian, which,
in America, may be assigned to either the upper part of No.
Ill, or the Oneida, No. IVa. It is a pinna (leaf) with large
leaflets and a perfectly distinct venation resembling a Neu-
opteris of the Coal Measures. Of this fern, our lamented
palseobotanist Leo Lesquereux remarked that "it plainly
proves that the land vegetation of that age, including
already plants of so advanced types, must have been varied
in character. Therefore, according to the law of evolution,
it is evidence that a still more ancient land flora existed,
probably contemporaneous with the first appearance of the
vegetable marine flora."
Several years ago Lesquereux discovered land plants in
the Lower Silurian rocks near Cincinnati, and descanted on
their importance. His determinations were at first doubted,
but have since been accepted by Saporta and other authori-
ties. The confirmation of Lesquereux' s views afforded by
the French fern is all the more valuable inasmuch as this
fern, which lived in an early Palaeozoic age, resembles those
which grew in the much later Carboniferous times ; and the
earth's surface was no doubt clad locally with ferns of that
type during all the ages intervening ; so that Upper Silu-
rian, Devonian and Subcarboniferous Neuropterids may
turn up in the future exploration of deposits favorably situ-
ated in regard to ancient shore lines, from which soil-laden
rivers debouched. Such ferns are therefore no longer to be
accounted characteristic of the Coal era ; and what is true
of ferns must be true of all other kinds of fossil forms. It
is the general fades or aspect of its flora or fauna which
characterizes an age, and not any one species. The identi-
fication of the same deposit in two geological regions, far
removed from each other, by means of one or two "charac-
teristic forms" must always be done at the risk of making
some great mistake certain to be discovered in the further
progress of the science.
It should always be kept in view that fossil plants were
drifted seaward from the mouths of rivers draining certain
kinds of land ; delivering therefore certain kinds of mineral
FOSSILS OF ONEIDA AND MEDINA NO. IV. 719
matter. The lithology of the rock must be quite as "char-
acteristic" of that special age as its palseobotany. As
land surfaces become worn away their river detritus changes
character. The same river must make quite different de-
posits in successive ages. Moreover the drainage system
changes ; rivers run in other directions and in other vol-
umes ; so that the same central forest-covered land district
may furnish very different successive deposits with the
same kinds of plants. On the other hand changes of vege-
tation are often rapid ; the Delaware and Susquehanna
rivers are floating deciduous leaves and twigs now into the
Atlantic, whither only a century ago they floated coniferous
foliage and fruit.
The same is true of animal fossil forms. The stability,
the number, size and association of types has always de-
pended upon the lithological output of the land-drainage.
This has always been changing in its direction, intensity,
extent, and mineral constitution the changes being
brought about slowly or swiftly, and often alternately, not
merely by movements of various kinds, but by secular ero-
sion, uncovering deep rocks to the surface, and removing
upper rocks from it. Therefore, it is impossible to believe
in "characteristic forms," in the dogmatic way in which
they have been adopted and applied to stratigraphy.
At the same time all the considerations mentioned above,
while throwing doubt on "single characteristic forms,'
tend to increase our faith in "characteristic groups," and
in their close generic relationship to characteristic lithology.
END OF VOL.
QE
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