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Tha laat racordad f rama on aach rpicroficha shall contain tha symbol — »• (moaning "PQN- TINUED"). or tha symbol ▼ (moaning "END"), whiehavar appliaa. Maps, plataa. clharts, ate, may ba fllmad at diffarant raduction ratios. Thoaa too iarga to ba antlrahf includ«id in ona axpoaura ara fllmad baginning in ttia uppar laft hand eomar. laft to right and top tp bottom, as many framaa aa raquirad. Tha following diagrama illuatrata tha mathod: -f 1 I ■ ■ /-'■» 2 3 L'axamplaira fiifmA fut raproduit grAca i la giinArositA da: La bibliothique det Archives nationaies du Canada Las Imagas Suivantas ont ^4 raproduitas avac la plus grand soin. compta tanu da la condition at da la nattat« da l'axamplaira film*, at an conformity avac laa conditions du contrat da fllmaga. ^aa axamplairaa originaux dont la couvartura •n papiar aat imprim^a sont filmte an commanpant par la pramiar plat at an tarminant soit par la darnlAra paga qui comporta una amprainta d'impraaaion ou d'illustration, spit par la sacond plat, aalon la caa. Tous las autras axamplairas originaux aont filmia an commaflnpant par ja pramlAra paga qui comporta una amprainta d'impraaaion ou d'ilfuatration at an tarminant par la 6mn\ktm paga qui comporta una talia amprainta. ■ * Un das symbolaa sil^ants apparaftra sur la darniira imaga da chaqua microficha, salon la cas: la symbols — •i^ signifia "A SUIVRE", la symbols ▼ signifia "FIN". Laa cartaa, planchas, tablaaux. ate. pauvant Atra filmAs * daa taux da r^diifition diffArants. Lorsqua la documant aat trop grand pour 4tra raproduit an un saul clichi. il aat f ilm« i partir da i'angia supAriaur gaucha. da gaucha k droita, at da haut •n baa. an pranant la nombra d'imagaa nAcaaaaira. Laa diagrammas suivants ilhjatrant la m*tAoda. ' 6 32 X THE TACONIC QUESTION IN (M G^EOLOGhY BY THOMAS STEl^RY HUNT, M.A., LL.D., F.R.8. S' IM- PART II. ^ FBOH THk TRANSACTIONS OF THE ROYAL SOOIETT OF CANADA VOLUME It., SECTION IV., 1884. I* »,v : •-■■iS S®:-v .MONTRBAIj: DAWSON BROTHERS, PUBLISHERS. ■ 1884. i. -X .■ frr r 'n.,. % f- ^K. \ ■'V^r^ ft' ['*;■■■ ■ ' J ■ ., -r- ^ ■-ii 'V o:1 i< V-.'-f: 'v ». '■■ {. 9l^>-i^■ ,f--- Sttmow-lV., 1884, [ 126 i . flUNS. tooT. SOO. OAKAbl. VI.— il Historical Account of the Taconic Queation in Geology, with a Discussion of tJu /Relations of the Taconic Series jo the Older Orystalline and to the Cambrian Roeks. J^ Thomas Stkkry Hunt, LL.D. (Cantab.), F.E.S. SECOND PAET. (ftpsented M*y 21, 1884.) \_ . VIII,— 77.f Kew6enian age, these sandstones and magnesian limestones of the Cambrian, lying in undisturbed succes- sion, have about 1,000 feet in thickness, and are overlaid by the St. Peter sandstone, which divides them ^m the succeeding Trenton and may itself be regardedas the base of the Oidovidan. When, however, we reach the Cordilleras, we find a great augmentation in .^e thicknees of these lower rocks. In the Eureka district of Nevada, according to the lato studies of Arnold Hague and Wolcott, the fauna of the so-called Lower and Upper Potsdam ranges through more than 6,000 feet of strata, and is succeeded by that of the. Ohasy' and Trenton sub^Visions. -i- 4 188. A similar great development of these W« woks eiists-in north-Weitem New- lb«lwQa^ virhere,^m his stoddw ortfieii wgj^^ ^^w ^^ to sdmit a soocsssio^ over 9,000 feet of pdiegwio straU below the Trenton horizon. '• ^ _f»WJ*!3.'!'i^iH^tf*«^^ ■^iisr ;'^;' ■VT"^«'flK^:«?l^4i*»riy^|,• 126 DB. taoUABjnas&Bit hunt ok the Theiiubdivisions there recognized bjrkim in wceiiding order ^ere : 1. Lower Potadam- 2. Upper Potedam; 8. Lower Oalciferous ; I Upper Oalciferoas ; 6. Levi* ; and 6 PhyU.- graptus beds The second and third of these were regarded by BilUngs a« the reprien- tatives ot the Adirondack Potsdam and Oalciferous, while the Phyllograptus bed; at the summi were considered the equivalent of the Welsh Arenig, which belongs to the base of the Bala grouR or the second fauna. It is evident, as BilUngs declared, that we have, in this great thicWs m north-western Newfoundland, a touch more complete m the Adirondack region, where the Upi^er Potsdam, Oalciferous and Chaay subdivisions reprwent tfe whole succession from the ancient gneiss up to the Trenton limestone f 189. Keeping in view the great development of the Cambrian alike in the Cordil- leras and m Newfoundland, as compared with the Cambrian of the Adirondack and Mis- sissippi areas, we are better prepared to understand the remarkable type assumed by this series m the Appalachian area, on the eastern margin of the American f aleozoic basin, from new the Gulf of Meiico north-eastward to the Gulf of St. Lawrence and to Newfound- land, along the western base of the Atkntic or Appalachian belt. These Cambrian rocks throughout this extent, wherever preserved. ar6 characterized by great thickness and con- siderable diversities in composition, due to the accumulation of mechanical sediments de- nved from the disintegration and decay of the various groups of pre-Cambrian rooks which mi^e up the a^'acent eozoic land. To this, and to repeated movements of the land during and after the Cambrian period, they owe their complex constitution, their great volume their disturbed and faulted condition, and their unfconformities. All of these characters serve to distinguish them widely from the horizontal and comparatively thin quartzites and magnesian limestones, their representatives along the northern border of the great basin as seen in the Adirondack and Mississippi areas. It is this Appalachian Cambrian many thousand feet in thickness, which, as we have alfeady seen, constitutes the Rrst' Grey wacke of Eaton, the Upper Taconic of Emmons, the Quebec and Potsdam group of Logan, and a large part of the original Hudson River group. § 140. That the Levip limestones and Phyllograptus shales, found at the summit of this series, mark the l>9ginnings of the second fauna has already been noticed, as well as the fact that still higher strata, of Ordovician and Silurian ages, are found over portionsof this Ap|)alachian Cambrian series, among the strata of which they have sometimes A involved by subsequent movements. It will also be borne iu mind, first, that this nest mass <)f 10.000 feet or more of diversified and folded CambriaA strata is soon exchanged to the west for a far more simple type of but a few hundred feet in thidtness- and secondly, that erosion has removed this great series wholly or in^'part from over W porl tions of Its original area, particularly south of the parallel of 4$» north Utitude. § 141. With these explanations before'us, we are now prepared to consider the rel*. tions of the Cambrian and Ordovician series, in their two Unlike types of the Appalachian and Adirondack areas, to the Lower Taconic limestones. It has already b^^ shown that Emmons, in 1842, in his final Eeport on the Geology of the Northern District of New Tork defined, with the present names, the lower subdivisions of the New York paleozoic sys^ tem, from the Potsdam to the Oneida, both indusive, to which he gave the coUeotive ap- pellation of tiie Champlain division. He at the 'same time proposed for the granular quMfai-rockand ttgffjmul^]toa»rodk^ ia western Maaaadmwitti^tiwmHiw ■*■• Wi4 Baton in assigning to 'a lower horizon than S' ■\** ■■ -fi-*" ^» > «h8n S- .'^^"'n*;^*',f #.•..},-?/.- ^..^--.i^^-'-j PAOONIC QUESTION Df GI :■ .s r /\;?Ji;'»*-(J/f<' Tf.Tk.vsrJti' (.,>T^'A> 127 ihfi Potflduoa sandatone, and in regarding as entirely distinct from the New York system. Tlie upper limits of this Taconic system, and its relatiojas to the members of the Oham- plain division on the east side of the Ghamplkin and J^ndson valleys, were not at that time clearly defined by Emmons. 5 142. In 1848 appeared tiie final Report by Mather upon the Geology of the Southern District, of New York, in which he rejiected entirely the notion of the Taconic system, and the whole teaching of Eaton, asserting that the Taconic jwas nothing more than a modified form of the Ohamplain division of Emmons. The granular quartz-rock of 4he Taconic he declared to be Potsdam ; the granular lime-rock, the Calpferous sand-rock^with the Wc- ceeding Ohazy and Trenton limestones ; while the overlying argillites, including the'v so- called Hudson River group, were the Utica and the Loraine shales. A similar suggestion had been put forth by Messrs. H. D. and W. B. Rogers, iiji 1841, for the like roc^s in New Jersey and Pennsylvania, and was cited by Mather in snbport of his view. When, later, in 1868, H. D. Rogers published hir final Report on thje Geology of Pennsylvania, the Lower Tacomc rocks of Massachusetts had been by Emmonjs traced south-westward through the great Appalachian valley, in Pennsylvania, and the {Adjacent and subordinate Lanoas- ter valley. These rocks, under the names of Primal, Aui^ral and Matinal, were now de- scribed by H. D. Rogers as lotoal modificati'C»'.' TACONIO QUESTION IN GEOLOGY. 129 V 4 I east ; in the first locality resting anconformably upon Ordovician Btratar«nd-in th^ second, upon a mass of eruptive rock which breaks through similar strata (§ 117). In this connec- tion may be recalled the like occurrenoe^t Becraft's Mountain, near the town of Hudson, on the east side of the Hudson River, long knbwn, and lately re-examined by W. M. Davis. Here, resting upon shales referred to the Hudson River group aii^^ from the locality, probably of Loraine age, there is found, in a smalT synclinal area, a mass of con- torted strata, including 150 feet or more of foAsiliferous Lpwer Heldcrberg limestones over- laid by as great a thickness of Cauda-galli shales, to which succeed a few feet of cherty limestone regarded as the equivalent of the Comiferous^or Upper Helderberg. * In all of these localities, as well as at Rondout, also reexamined by Davis, we note the absence, beneath these Silurian strata, of the great mass of mechanical sediments, including the Oneida and Medina sandstones, which, farther west, are so conspicuous in the lowi&r part of the Silurian series, and belong,tp the Second Graywi^cke of Eaton. § 148. As already mentioned in § 118, Augustus Wij»g, having detected in Vermont fossiliferous limestones of Trenton age, the locality was eiunined by Billings. In a section eastward from Crown Point, in New York, the latter found what was described as the Red Sand-rock, with Olenellns, brought up by a fault, on the east side of the Loraine ■hales, and followed eastward by strata carrying the fauna of the Calciferous san4«ji?k, succeeded by some forms of the Levis, and then by the Chazy and Trenton ; to the east of which another dislocation brings up again a limestone abounding in the typical fauna of the Levis limestone. The close association of the latter with the white marbles quar- ried in this region, led Billings to refer these to the Levis horizon.* It is worthy of notice that it w4s in the same vicinity, ^hic"h furnished Billings with Calciferous, Levis, Chazy and Trenton forms, that the organic remains had been found which were referred by Hall to the Niagara and still' higher horizons, and which \^ Edward Hitchcock and W. B. Rogers to conjecture that the marbles of this region might be of Devonian age or younger. So perplexing were, these facts to Wing, that we find him led to the conclusion, announced in a letter to J. D. Dana in 18T5, and recently cited with approval by the latter,' that " The Eoli^^l^estone of the Vermont Geological Report embraced not only the Trenton and the HiraiMn River beds, but all the formations of the Lower Silurian as well, and even limestones and dolomites of the Red Sand-rock (Potsdam sandstone) series." ^ 149. Another hypothesis touching the age of ^he Taconic marbles was now offei^ed to thf perplexed geologist, and this time by the Geological Survey of Canada. We have already shown that forced by the paleontological evidence (which had previously been urged by Emmons), Logan, in 1860, adopted the views of the latter as regards the 'horizon of the Upper Taconic, long before traced from New York to below Quebec on the St. Law- rence. This, in accordance with the conclusions of Mather, and the earlier published view of Emmons, had been described by Logan as consisting of thb Hudson River group with ' Amer. Joar. Science, xxvi, 381 and 389. , - * Hunt, On Some Points in the Geology of Vermont 1868, Amer. Jour. Science, xlvi, pp. 222, 229. This paper, from data furnished by BiUingi, was written while the writer still accepted the antenabte view of Logan, from the fint ojpfneed by^Wipgs, which assigned the Levis to a position near tl^ base of the Cambrian series, instead of its smmoit ' ^ ^ » Dana, The Age of the Taconic System. Qnar. Oeoi Jonr.. xxxviii. 402. * ■ ? » Sec. rv., 1884. 17. ' r ' -t* V f -Jilt *-•. k'^^* •Sm^ S„^ j- ^ '^' V ■; I 180 ©H. T/IOMAS STEKfiY BUNT ON [K- - or «iop.,„, b;.;;;;. - 7'^ - ;-^ .-o' .We .he t^ .;„ita.r;„"eThr,.'Zd" .V /I 1 .. -•"■""^''^l' be,.g the olde.1 „d no, thL„„grttlt7^;[ " '"^'f^ «-• the SUI*y .„aZ: I twee, the Sillery and the LeL, whiohl he hl^ ,, i t" ^^^^''^''^ "trata found b^ herockaofh,.Quebec^,,^^^^^^^ ^oZt^, of the Wer Taconic, Logan Xs Jed to inclndlT , ^* ™'* *^« S^'''^"!" marbl J iLi !o" "^^ ^° ^" ^"»« illogical UaT of c-T' ?'"' "' '^''"^y ««* ^^^th in iMhed in 1866, after he had spent some tiT , "^ *"^ *^« No^l^eni States nub montandMaaaachnsettsinto^a^trNfc ^ ■ - M^-husetts is represented as an uX/rtpted cT r *'!•'""" ^^^«»^'« "--*<>»« ^m the province of Quebec, brought up atnga^ar -"T*'^" ''' *^« I-^" "mestone oyerlyiog u. successively, the LauL and Sn?« / "*'' ""^ having 6n both sides the anticUnal having the onlinar^o^ tt rc^wT "'t'"^' °" *^« --* «ec, I eqaivalonfr of "flayed upon > llery, and the »n,) the "Lftvig^ and there can i^y sandstone ed. This his- ^ tfthfeSiUwy ch have been ta found be- Following nlar marbles ip, And to re. set forth In States, pub- 'estern Ver- c limestone 8 limestone both sides ^0Bt side of a or Upper the Green Logan was' lline rocks, the Lower firmeid the interpreta- tpne to its In either conglom- ir Taconic he fosBil- nic; that sitate, ixT B it hap- ' > be th^ i», — they sLo^wer A %'■ ■ ^* ™- ' \ ■ *■■ ... . ) « ) <» • ..\- tACQKtO Q^RStFON IN GJidtjOQY. lai wef faconic of Emmoiis ; 2 and 8. Mid- dle and Upper, including the uncrystalline fossiliferons Scrtoton and Gkorg^a sUtes, and the overlying Red Sand-ro -k, which he fegardad fts the equivalent of Potsdam. The suc- ^ oeeding graywacke^ constituting a^mat part of the Upper Taconic of Emmons, was by ' Perry supposed to be separated by aft unconformity from the ited Sand-rock, and he was disposed to divide iltfrom the Taconic and connect it with the Champlain division/ (■ f 162. Still more^ocently Marcou has gi^en vp his owii latest views of these rocja in Vermont. JThe true or typical Taconic is^ according to trim, the UpperTaconic of Emmons, jj^ and rests unconforn)ably upon the-Lower Tacoujc. This upper series he divicles into four parts, in as^nding order, designated the St. Albans, Georgia, P>illipsburg and Scranton groups. In thtise tfre; found, besides tbe Primordial fauna, fosi^ils of the second fauna ^ in in^blded limestones, a fact which he explain? as indicating cent^ei^ of creation in which the forms of the second fauna first made their appearanqjjg^the whole- of the^e being, ac- cording to him, below th^ horizon of the Red Sand-rock, which he supposes to overlie, un- con|formably, the Upper Taoonic." T^at the forms of the second fauna, fonnd in porlioiis - of this region, belong to a lower horizon than the Bbtsdam, i^m discordance alike with with the facts of paleontology and of stratigraphy, and is opposed to the cpncjusions of all oth^r observers in that region, including alike Emrabas, LtOgan and Perry. Marcou's con- clu^ons would seem to be based on some of the frequent cases of inversion of strata, or of dislocation and upthroA^, to which we have elsewhere alluded, »nd which led Logan ta place the Levis limestone near Quebec at the base of his Quebec group, and to represent' the iTaconic marblate of southern Vermont as passing • l^ebw the crystalline schists of the Ghreein Mountain range." r ^ It should, howeirer, here be said, at the same .tiine, that in a disturbed region like /^aste^n Vermont, w\ere areas of the higher rocks of the second;finma (Eixist, and have prob- ably it one time been more widely spread thin now, it is not impossible that 'there may be outlwrs of a sandstone of Oneida or Medina age, such as in Pennsylvania we have described: as overlying unconformably Lower Taconic rocks, and also that such Silu"rlan sandstones may have been confounded with the older Cambrian or Potsdam sandston?^ and thus afford a seeming justification for thjg strange hypothesis advanced by Marcoq, that the wholp of the Appalachian Cambrian i^ Vermont is older than the Potsdam- sandston^.' The ^bsehce of these Si^tirian sandstonea-at the base of the outliers of Silu- rian limel^tones &, Montreal, at Hudson and elsewhere, as already noticed in J l4t, renders, hcf^eyer; t^ir presence in Vermont less probable. ■ - $ 158. ^e studie^ of the last few years have thrown much light on the character of . the lower ifertions of 4he Cambri^ in its development to thes^ist and south-east of the Adirondack area. It has l^ea-odticed thit the Eed Sand-rock, and its accompanying slates and Hmestones near Burilington, Vermont, referred by Emmons to the Potsdam, but by. Adams, and W. B.Eogergid^the Mcfdina, and by Logan to the suminit of the Hudson Eiver group, were subsequently by^Mlings called Lower Potsdam, to indicate that the fauna of these rooks belongs to a somewhat lowerhorizon than the typical Potsdam of the New r » 15»t Bed Sudrock of Vermont, etc., J. B. ^tory ; Piroc. Boe. JkwT N»t Hfat, 1867, vol xi • M«noa, Bull Eloc. CMoL de Fnuus, 1880, (3) ix, pp. 18-46. 1* ,^ .•-.M -;j ■:\ i I *^ f^r ^■ m 13^ BU -THOMAS STEEHy HUNT ON THB Liter here occupy their „.lural p»ili„„ ^^1 Inm™i r'.K n ''^' "' "' ^™ »«»• '""'* Matji^ md hi. followers, of totufbed "d ^' f'T''"'-'. «»«i«led. not s. t,u^ ^^ : ..tone,.„d„fthe^„,tLirrd^::hZ\*:^^^^^ r*" "■" "-Trento^ W farm, of the iir.. f.„„, ^, ^.^^ alSy: »■«"'■ T"^'^ '- 1"^ "' '-t. U-e mi. he returned to the subject miJ^rrT ! ""r f""' ''"'' '" ""> »'d" »ne». In , "..t "we now know .ppro^ta^,';*;^r^!:''^''!r^"'''--«««'-.-.^'«dS llonj «,d there i. u„w no longer .nyTuern twT" " """^ '"* "» "'''o' ''"""■^ the Trenton limestone, do occupy Jh'ridt^ the K . "T ™""' " "» "^ "•»" m.Ie., .nd continue along the v.L for 4anv mi Wf ^K ? "'™ *" ■""''' ""^ '^^^^ tem, Hudson Eiyer group has therlfl / "''f *"""»■ '»«'"ds Lake Champlaia. The ot superposition -dS'^^l^^s Th^etrTav ""f "1°°' '''"" "»°>"'« «^"ow J^' ««tw.rd. at a time when their fos 1 InLri!S'n'„''t r"*^"? ,"■« "'™ "> "-ks on tL toown, M,d their geological position hTnot h f . "''*''^' "* "'^"'' « '""t, nn- We We al™«,y rt„w? i„ ^7^°"^ h^w T^nx r;"."' '"' '^*'' -™»«tion ." » '^'.des the trneLoraine shales „.hrdiIrblT.r "" "'T"""' "™ '» -'"'-i'. \ """overted age, which he supp^^ milTt i "''/P'""*»"y "on-fossiliferous rocks of ' ducedmuch of that confusion SrCt^'^;:;'"''';,, ""V"' f"™''' -4'l""i»tro. g^P .s the equivJent to that of Lorrc^wl'j*" *'"™ °'""' ""■" "'Hudson Eiver a Jed":. '-TH^rii:rxrnxr^-f '■^.^-^^ I«e»), portion, of the soK^ed OuewT /l """""^ ""'« "««• <" mapp^ by found in this position at:^!:^^,:^ Hroft 'y:!;; °"i' ''°'-'""' ^-•^'"^ "» .olufon of this problem than the carefuUtuZomr^ w"! T T'" """^ "°" '" *« the existence of fossiliferous recks of thi. W °' "'• ^- ^- ^°^. "ko, in 18?1, discorered op his investigations, showed^. ttrs^r^T"' '^'"'' "'"' '*'°* *"*■ '""'<""■■« ^yPotadam age, (cor^sponding to tSe oZe ta IZ'T'^ " ""■"'""' "— »' Wef 'At Bic, Quebec, and at the sfrail of SeWe in ?lt 1 ^'*"' ^«™°-".«"l to the bed. eastern dde „f^ fault, .gainst the 1^"™ ^h'^^^'tn •"" "' ^^ "'"»«'" "» <"" «» oently traced these lower Potsdam rock. n^^„ .,^''"™'>» k" 'Indies Pord h«i re- ef ft„umbia and D»=h««, tim.t. , ??I'W; "fC"""!* *«p. .xli, pp. MMSO ^~ Hall, RxK. AmerAflyxv Ad T. Sc to nce,ia77, j,. fl e;^ ^Amer. Jonr. Sdenoe, 1878, vi/pflsT^ *^ ■w ■ J ■ .-% ^'■^ 4tW , ^^^'' 'T"x'^ '^'"^^M^'.-^kji. '^^''^f riven by him in uth dislocation, evisage, which ic or First Gray- rn that farther anner, brought Q River group, as taught by Trenton lime- rt, at least, the ese facts, Hall )lder ones. In ion, concluded I older forma- e rocks above one hundred mplain. The te knowledge rocks on the J. in fact, un- imination."'" t to include, rous rocks of i thus intro- udson River valley, being gan's geolo- e uncrystal- mapped by shhad been more to the discovered ', following ' of Lower to the beds up on the >rd has re- rious parts )w of the Q estimate %* ■■_* I'AOONIC QUESTION IN GEOLOGY. 133 the thickness of this series of Cambrian sandstones, shales, conglomerates and limestones, but says that it " is manifestly very great in eastern New York." " § 156. It is hardly necessary to mention that this series of Cambrian fossiliferous rocks, traced by Ford through Rensselaer, Columbia and part of Duchess Counties, along the eastern side of a belt of Lorjiine shales, is a part of the great G-raywacke belt, the age of which was disputed between Emmons and Mather, (the Hudson River group of the latter), and which Logan, after his examination of the region with Hall, in 1863, described and subsequently mapped as Quebec group. Thes^ observers, as has been already stated (§ 115), and as may be seen on Logan's map of 1866, then traced a narrow but persistent belt of Loraine shales along the eastern side of the Hudson, from Washington County south- ward to a point a little above Hyde Park, where they found the boundary between these shales and the older group to cross to the west side of the Hudson. The accuracy of this delineation is confirmed by Ford, who, while remarking that the distribution of the upper rocks might entitl^Hm to be called the Hudson River group, suggests, in view of the perplexities which have attended its use, that it would be better " to discard altogether the desi^ation, and go back to the old term, Loraine shales." Ford farther speaks ^f the " great dislocation," .which, at so many points from western Vermont to the Hudson in Duchess County, brings up the Cambrian rocks against newer strata of Ordovician age. A reference to the sections of Logan and Billings, already cited, will, however, show the existence, not of a single dislocation, but oS parallel dislocations, with upthrows on the east side, towards the barrier of older rocks. Of such parallel ff)ilts we findj in fact, re- peated examples, not only east of the Hudson, but ^ther ^lithward, along the eastern border of the Appalachian valley, as already showti in § 101. A § 157. The one continuous break, with an upthrow on the south and east of *JfiOO feet, extending from Gasp^ to Alabama, imagined by Logan, was required in his struc- tural scheme, because he had assumed the Levis limestone, (which near Quebec is brought to adjoin the Loraine shales,) to occupy a position at the base of his Quebec group, and to have been originally buried Y.OOO feet beneath the Loraine shales in a great con- formable series. The strata along the west side of these dislocations in Canada and in Vermont are, according to Logan, either Levis, Chazy, Trenton or Loraine, the Lower Potsdam being on the east side. In a section described by Billings, and already noticed ($ 148), where the first dislocation brings up the Lower Potsdam — which is successively overlaid by Calciferous, Levis, Chazy and Trenton — against the Loraine, a second parallel fault, a little farther to the east, brings up the Levis against the Trenton. We see, from the late studies of Ford, that the great belt along the eastern border of the Ix)raine shales, whidi Logan described and mapped as Quebec group, is in large part Lower Potsdam. The whole series must now be farther studied in the present light : we must know the real thickness of the Cambrian in the region in question ; the interval therein which separates the Lower Potsdam irom the Levis fauna ; and how much of the Quebec group of Logan is to be included in the Potsdam. $ 168. As regards the relations of the Cambrian and Ordovician rocks ovet this area, we hare already shown that there Lr^very reason to believe that there exists a stratigraph- ical break between them, (as is al[k 86 and 206. »,. p^y'''-\mm '#" 'W^' .f ■ 'ii / ;- ' if /. « S^\/t t> 'n*\^ - tf r i i k ■'w^'itM :.*>. i ■ ! - i- : W 184 Dfi. THOMAS STBRRT HUNT ON THET iTJT^'h *^^« o-t and present imgulari^iestlier T'^' ^^« ««^e«foires of tEe Tren- . o Hall and I^ganjt appeared that fhe"^^^^^^^^^^ Although, according s^es passed from the east to the we« IZ o tie Hud^ "' ^'*^" ^"' *^« -^«"- ward on the east bank." Dale, in 1811 found ZT / . ^'^^^' '*''"*^ *"a^t^«r south- Poughkeepsie, ^d Dwight 800^ after deteZ ^ '^' ^''^°' ^^'^ ^'^ ^^^^^^ ^t ^one of the Wappinger valley a mtlfaSl Z^"""' ^"^"*« ^^^renton age in the lie bank of t,, Hudson.' These lC!:ZV^\Zti:: ^fl ^ ^^^^^^^ ^ *^« - of Calciferous age in other limestones in tie wlIl ,? ^^ '^'* °^ ^ remarkable fauna^ ■ sils of the Calciferous, the Trenton and th« T P«*«dam, of strata carrying the fos- covenes by Dwight were n»ade n is" - 88o^anT '^'^^'''^- ^^^^ reLLue Z- those of Ford, show the exXnce in what hi Z ' ^T^ *° ^'^^ obsery'ations of Dale a7d ^oup, of fossiliferous strata "n^ng frl^h^^^ «-- group and Quebe^ cWe,-a result identical to thafalrea^" ^.^.^ ^^ 7 *° *^« ^^^^ ^tlt^ been successively mapped as Hudson R^er Zp at O T"^" ''' *^« "^'^ ^^-^^ ^ad 5 159. Having thus recalled thn 1? . ^ ^ ^'*®*'^<' ^o«P- the predomm.nl 0.mbri„, we m.yZceLT^!l 1"^ °' °"»°™''" '«*» with he T.comc „e»H„n. He, in ,872 ™d wf^J ^! ' ™'" °' ^^f- J- »• »•«» oa from the organic form, found in «eoci.l.^r^th '^^?""' T' '^'"^'^^t'. ««d ree«,ning the conclueion th.t the Stockbridge1Z.1T* ""!'" ''""»'°»« » Vermont, re«i^ being of the Had.on Eiver gronp^' C w! " °"""'''' '^"'"'■■" "" overWn^^c^l. a^ment, m.y be found in f^^r on fte ^, '"'^T'' '"^'^ "^ ' .trL^r^tS Qn^ler y Journal of the OeobgS ^ etv^Tl *? ^f -' "" '''«'■"•= Sy.t.m fa l^ . hietoricl in.r«lnction ,„ the fubjectCaWr' ",' « ''?°"' "''■ ^^--Z^g ™k. l^"*"'' ""*" '■5' ^""O"' ii hi. G^ '^ "f^I « deflaition of the Taconic .ysteif pablBhed in 1842, while hi. view. w^L , ^ "" '^°'"«"" ™»W«t of New YoT even .Indied the relation. Jtl: TZI ^'*'"' ""* ''»*"' l" kad clearly dlL^t jaterat^tified and immediatTfy o^oll! "^ '"^'^■"^ *« Kraaalar lime-rLtt^a": Wer T«»,„ic With the grit wL^J^ '° "^"^ '»«<''''" -mrtititing the I->gaah.Te.Iil*pl.<,ea rfwve it and^Wk T^'"*" ^'o"' ^no". Mather and a-on.. Thi. ,.„„ a. wrwell"'"^r '''->'-» V'T"y Emmoa. notice. «,e ooS:;:^l'tf* ^ ;:^t ^^T^rT " """"' "-="-". "Amflr. Jnn. 0_1 .. — — _ Jbtd., xvii. 389; xlx 60- ixi 7o ^ 1*- ^'Vlk'^ v*|i#'. "-^"^'^i^" *"'" * oiresof tieTren- liough, according I and the inferior Park in Duchess ta farther sonth- riod in shales at age in the lime- irg, on the west markable fauna^ ttg the presence wrying the fos- remarkable dis- ns of Dale, and up and Quebec ffaine. both in- •ea which had Jearch among- an rocks with J. D. Dana pn of papers on md reasoning nont, reached ■lying schists ratigraphical rstem, in the erein, giving conic system New York, r defined, or ack, and fhe itituting the Mather and Taconic by base of the lline strata i for a long eachusetts, >mpanying ■ 'any lime- TACONIO QUESTION IN GEOLOGY. 18S ■|p rock of Eaton— followed to the east by two other belts, differing from the first in lith- ological characters, and constituting the Granular lime-rock of Eaton. Emmons then pro- ceeds to inquire whether these three may not be one and the same bed repeated, or, in case there should be 'two or more distinct beds, which belt is the oldest. " It is," he says, "a question whether these three several belts of limestone m»y not belong to one bed ; it is at least worthy of attentive examination. It is, however, a question that I have often sought to solve, but I have not yet succeeded in a way which is satisfactory to my mind, but I have concluded to regard them as distinct, inasmuch as there are differences of some importance," etc. It had been customary, he tells us, to look upon the most easterly belt as the oldest, and that at the western base of the Taconic range as the newest, notwith- standing the fact that the most westerly belt seems to dip beneath the eastern. At the same time he remarks that, in the absence of fossils, " we must judge of their age by their relative position, or by superposition, and, so long as the most western belt, by thi$ rule,, is the inferior one, I can see no necessity in the case to suppose a series of complicated changes, in order td make it coincide with our conjectures." '* § 161. A careful perusal of the page from which these extracts are taken, and, indeed, of the citations themselves, suffices to show that Emmons 'was at that time — lfe42 — iu doubt which of these limestones should be regarded as older and which younge •, or, in- deed, whether they were not all repetitions of the same belt. These doubts we: e, how- ever, resolved by him, and those familiar with his subsequent studies and publications are well aware that he soon afterward saw reason to follow Eaton iU assigning the Sparry lime-rock of the western belt to the summit of the great Greywacke or Upper (Taconic-. series, which he showed to be fossiliferous and Cambrian in age. The whole history of this is before the world in Emmons' later publications of 1846, 1855 and 1860, but of this, in 1882, Dana tells us nothiug, and, after asserting that the Taconic rocks constitute one conformable series — which, so far as regards the Lower Taconic, has never been questioned — ^refers to the well-known fact that the limestones of the western belt described by Em- mons, have since yielded not only a Cambrian, but an Ordovician fauna, and then, falling back on the words of Emmons in 1842, already cited, declares that "if Professor Emmons* view is right with regard to the western and eastern limestones and the intermediate Ta- conic schists, namely, that the order of superposition is the order of age, then the western is the oldest of the three ;" but, " inasmuch as the western limestone is partly of Trenton age, it makes the eastern limestone younger still, or, a part of the Hudson River group." " Dana, however, adds that he accepts the alternative conjecture of Emmons in 1842, — which lie assumes to be established, — that the eastern and western limestone belts in question are but repetitions of one and the same stratum, and thence argues that the granular marbles of the Taconic range are altered lower paleozoic limestone. J 162. The different views with regard to the geological horizon of the Lower Taconic or Stockbridge limestones of Emmons — the Granular lime-rock of Eaton — may be resumed as follows : — I. That they are pre-Oambrian, and occupy a position below the Potsdam sandstone or Bed Sand-mikt and the Quebec group of Logan, which together constitute the First or >»i ** Emmona, Geolugy of the Northern DIatrict of New York, p. 147. " Qur. G«oL Joonial, xxxviU, 466. ii^ '.« .i.ti^ I ! I ■(;■.] ide DR THOMAS STBRRY HUNT ON THR Sp-rytae-rock, imagined bTwotifetT "T'"'*''''' "' ""■ I''™ 'imesle or par. of the Quebec g^„p .boy. ^L^":^'™" -^ ^""''"'^ "='»" •■"» «» =^5 HI. That they are the all,l( . . ' K«''°S"'«1 map of ^866.) the New York ^LJ ^s^^^t^lT^T "' "" ""* <" *' «-.'»ne. which In stone and the Utica elate. (mZ° flTand wTC""' T^i,™" ""» S""™ sand" IV. Allied to the last fc f !,« ^ ■^- ^S^^^> J- D. Dana.) -'■nr""™ "f «"« "-t:nt™Thr?::si''» ir "''■ "" ^-^ '--'» *»« with the Trenton and the Loraine or TI.,^ »: ^""^ ^""t" °f W»n, loirether of the Oha„p,ai„ division ^TZj^l^^ZTTr °""' ^°^^ ' -^ « Oneida. ^ <"' «y«tom, from the Potidam to the bkfe of the Second Graywacke. the third wa« devis^r^ a «° « W *"^ ^^^^^^^^^ ««Perior to the wacke, (maintained by Eaton and Emmons but 7 . 1 'J^' '^''*'"^« "^ *^« ^^i^* »%' mto favor by the conversion of Wan rthl l t .\^ ^'*'^'^^'^ ^^>«^ ^^^in brought «on that the Wer Taconic liZto, in W:! '' f m"^"\^'^' ^ ^" ^-^^^ adX great mass of sandstones, conglomerates iJlT ^^^^^^^^etts are inferior to a stunting wh^he called the Won and S^" ^ ^ ''^ thousand feet in thickness, c^n^ ^ 1«4. If as not until afte"" chant o7vT ""{ *'^ "^"^'^ ^^^P" ^eat sedimJtary or Graywacke series orTn nth '!,*° *^' ^"^''^^^^ ^o^^on of this that its plaJwas below ITd not aWe ^ TrenT "^^' *^" ^« ^^'^ --^^-ed the a^ amine the |wer Taconic rocks in weste^ N^w F? i T*'^'' *^"* ^^^^ ^e^an to et tion, placedke Levis or Sparry LIrtk at ^ f "^ ^^^^ "^'"^"^ *^«°' ^ a misconcep. elf "rr"" '^^^'"^^ '« t^e -^fo^y^^^^^^^^ -mmilof theaaT TasT X" °' *'^ ^^** Appalachian val^yt^^^^^^^^^ a 1^*^^^ '*^^^« '*^-« t^e iw' metamorphic condition. Logan w^ led L 1 T''' "^ *^' P*^^*^^<>^« «*^ata limestoneasanaltered representative ^ftheL^^ll. T" *^« ^^" laconic, - Potsdam ; the immediately overlying chLte ZZ'' '"' ''' ""^«'^3^^"« ^-^^te g omerates and shales of the Grayw Jke seriert . ««cceeding sandstones, con- divasK>ns Of his Quebec gro^p. H^e the "^. '^"1 ''^'"^'^ *° *^« ^^'^^'o^ and Sill2 g^ven under II. and thaHf MaZ Jd lirt/'^"'"'!: ^^*^««" *^« ^«^ of Log^^ Whale both would place the W T^'f 7'"'^^'^^ ^« ^'^^^ numbered H? below the Oneida, Mather imag^^rthr^ 'Z T^ ^^^ ^^^ Potsdam ^nd OMovzcian and Siluri« (that is^tica. I^ra^e 'd (^ 7f ^^T ^^^'^^^^^ t'^^"^ to be Eaton. Logan, on the other hand. conceW tL . "^ °' *^^ ^^^^^ Gmywacfce of Vermont. Massachusetts and New rrkTl i T "^"'^^^^^ ^^' »» «een bV him in The error of Mather and of H. a E^ers was t^bo^h f ^, ^r'""" ^' ^^^ ^-^-^T of sandstone,, conglomerates and sL^Z'!^\'^l''^':^'^^--Bniz e thi s greaVserie. Of sandstone,, congl^rr^. "^dT;::;^!^^^^^^ ^4_ i;^ ^j4 .^. , *Jv ^-•■."-^■*i«:^ "^'h "-'sT' -T* ■*■« "ff' as shown in the '-ack&i series, they evis limestone or low and the chief I eetones which, in e Potsdam sand- hey* include the Logj^n, together ?^ords) the whole the base of the te true Silurian Jse various and I^wer Taconic superior to the the First Gfay- again brought I farther admis- i inferior to a thickness, con- oup. orizon of this ■nized the fact began to ex- ' a misconcep- ■ of the Gray- iks along the tleozoic strata >wer Taconic, ing quartzite istones, con- a and Sillery w of Logan, imbered III. otsdam and them to be "aywacfee of by him in Sraywacke. great series PpalacJiiaii i. 'A TACONIC QUESTION IN GEOLOGY. 137 valley, and co-founded them with the Second Graywacke. This error it was which ^ completely misled the Geological Survey of Canada" up to 1860, and continues to obscure the subject in the minds of many American geblogists to the present time. « $ 165. It should be remembered that, as already pointed out in Chapters II ^nd III, the overiying Graywacke or Upper Taconic does not incliide the schistcjSe rocks immedi- ately above the Lower Taconic limestone, but that a considerable amount of crystalline schists and argillites occurs, both interstratiBed with and overlying this limestone, and forming an integral part of ike I^wer Taconic series. We have, moreover, set forth in Chapter V, evidencesoof the distinction between the Upper and the Lower Taconic, and have shown that the latter is not limited to the great Appalachian valley, which confines the former, but is met with in more or less interrupted belts lying upon the crystalline rocks of the Atlantic region, south and east of the great valley, from New Brunswick to Georgia. Thus, in North Carolina, not less than four distinct an(d separate parallel bands of the Lower TacOnic are met with between that of the great valleV and the overlying terti- ary strata of the coast, while similar narrow bands of the same roc^s are found in southern New York and New Jersey, lying upon the ancient gneisses. With^ none of these Lower. Taconic belts outside of the great valley, safar as is known, is theVpper Taconic to be found, its absence being due either to erosion, or more probably, as su^ested by Emmons, to the elevation of these areas above the sea during Cambrian time. § 166. On the other hand, it has been shown in Chapter VI, thatXwhat Mather re- garded as a continuation of the great Graywacke series ft-om the eafit c^ the Hudson, ex- tends south-westward across Orange County and, according to Horton, therfe rests, with a high eastern dip, on the north-west side of the gneissic belt of the HighlandsX Prom cen- tral Vermont, north-eastward along the great valley, to the St. Lawrence belW Quebec, the Lower Taconic is not known, and the Upper Taconic or Graywacke seri^ rests di- rectly upon older crystalline schists, as in Orange Coi^ty, New York. The s^e condi- tion ef things is again seen in NewfoundFand. These facts, already given in detail, serve to show the distinctness and independence of the crystalline Lower Taconic from the un- crystalline Upper Taconic or Cambrian series, which two were probably separated by a considerable interval of time, corresponding to the stratigraphical break, long since pointed out by Eaton, at the base of the First or Transition Ghraywacke. § 167. The student who refers to Dana's papel- of 1882, already noticed, on " The AVe of the Taconic System," will obtain no light on the question of the Graywacke series, nor indeed any evidence that the author has ever seriously studied the literature of the ques^ tion, or comprehended its relation to the complex question before us. He will get no^ notion of the two opj>osing views as to this series of rocks, or its position as above or be- low the Trenton limestone, or' even of its existence as a great succession of uncrystalline sediments, many thousand feet in thickness and distinct from the Lower Taconic lime- ttones, as maintained alike by Eaton, by Emmons, by Mather, and by Logan, and as set forth in the preceding chapters. We leave it to the reader to seek for an explanation of this incompetent and partial statement of the great g^logical proldem under discussion by one who assumes to be alike an investigator, a teacher, and a critic, and forbear to fol- low him into the details of his criticisms. ^ 468v^ (Fhehypotheeii of Matheraad H. D. BogerB~aB tothe^tiotrer Tocffiolc Yosfei Wm • ' Sec. IV., 1884. 18. « / MfeSSjt Hi /^^1i*&'t« ! / 138 DK. THOMAS STERKY HUNT ON THE known tabdivisio^,, „nW ^^211 1 ^^.n-nd^k, .„d inchding the «i^ weU- tion. and s«cc<«.i„n of .h ^,^2' ^^ were l"? "Z^^ """'"''■ """» ""'"o"' e«t of thi. region, however. bey„° dT^e cZT?" /^''T ''° ""■ ""' ""* «"'"'• founi other cry,l.llihe roek, unZ theXw '^ .'"'' *"''~'' '"''»'• "«"« wero very ditferent in physic charlter Jd in^H' ^T' ^^ °'''" "-oryst Jline .edi»ent. of the northern district of ^T^k T^°''«"f <"''''''"'*<' fr"-"*' PaWic . I™,, th^e nnlike rocks in the two reg^^ llrvZ^ T""^." '° '"' <^<^««°nof foxiy OTived at a system of el«iiB .• " . ' '' ° »™'' S«">e™liz.tion, h»i al- o«tern,or AppJaohCreXn tf t^f „^^^^^^^ '°."'""'' ''° "'"^"'''^ «"> "'*»<* « «!■• oia gneiss, and *^.t m^^o Tdil^'" rr'""'""' "'*' <•""' """ "■» P"""- in the eonlempora^ -".T.i^e AdtrdlTrX '" "'"°'' ""'"-^ •""""' ™^°""' whiel'i».r„?o';trXt^;'a'aeTr"?''^'=°"'''"«^^^^^^^ eaat of the Hudson differed ItthWoIalW J -""""«'"«'. »■ "M, that whatever to the - ftom the paleozoic roeL of NewTork J» f "^ ''"""*"' 8'""»« o" the one hand, and other, could be «othi.g 1 L ^-7^2 T " '"' ^'"""•'""' ««">■>■ o" ">« -^»ive stage, of so^lledmTa^XmJsel^r^hT'' ''i'''' '"^ '""'■<'"'«' " marbles and the crystalline schills wWchT: u ^"'" ^'"°''''' l-^rt^ito. and . .ncceedthen. farlhjrto the et ' iS 1, Z"""" "«"°' ■* "«" "» 'iose others that the more or less altered eoniv^lts Sf It T"' H"""* '° "'"""■ "othtag bnl Potsdam sandstone to the LLnelaks w. ^" °' "f, ""^ ^"'^ '"^'^. f"^ the ^tending along the eaat IfdrflttH^r ^LTch^^^'n'^r t^ T^ •^"' § ITO. The considerations which lent nVohAhilifTr t« +u- > eral resemblie of this Graywacke seriLfo^l^rn ^^ to th^^ ^.^eme were, first, the gen- of the New York system, to Xch it wT W mI""^'^'"^^^^^ ""' ^^^-* subdivisLs the argillites with unctuous IhTsV^alkr wJ '"' ^"°"'^^' *^« ^-* *^-* agreed with Eatou and Emmons U ^Z^nt^T T "f ^'^^^^' ^^-^'^^-^ which he certain resemblance to thC^Ca Llna Z. IT 1 1"'"* «r»y ^acke, presented a the so-called Calciferous slu^ "k and the un^ 1 "' p '^°*''" *"^ ^^^^^^ ^^^-^o--. parallelism from the top o'i^XV^l^^^^ '^'^'^^^- ^^-^-ral ;Eaton only the great law ofrvpTI ^ downward, which suggested to the mind of -opted (y H.B^rand b;^,wra';rrdetsr rrtV^^'t'' ™ ■ CitLi:ant^,:Lr:^;",;:^gtir" ~"--7:r.: notwithstanding its many mineXSd^ ''T ""^ '"'''*"* '^'"'«''I»"«»l». thickness, that U-l P"=:Xte*X^:''di:Srwhiot"^r ^ "• «""' in groups of sedimentary strata at verv v.ri™ i . "'""'.'''"<''' " 'O often mnarked ^.pects, more like th^V^^trgl^T ^^^ ^"^'^ » » ""»• ^ cert™ unfounded, than their App.,.11 ^T^^'J^^Z? "'S "'""'' " ■- ""^ -.«. the --M -^ .hO«-otTB^n|^^Ssfr^^-„^^ I I \ ■ V t«k- « "TWSM /■ V V / . TACONIC QtTESTlONr IK GEOLOGY. 139 > / (^ ' , . 1b fouAd lying Mween the ancient, granitoid gneiss beneath, and the Oneida sandatone above, precisely as the Potsdain-Loraine succession in northern New York intervenes bet- ween the same gneiss and the same sandstone. ^. _ § 111. It was not,- therefore, surprising, that thj geologists then engaged in the study . of Pennsylvania; New Jersey, and sQuthern New York, should have accepted this plausible and, at first sight, natural explanation of the apparent lithological parallelism presented between these regions and norihern New York, or that Mather endeavored to extend it to the rocks east of the Hudson. This attempt led him to assign to the great Oraywacke series, which we now know to be of Cambrian age, a position above the Loraine shales, or, m other words, to confound it with the Oneida, Medina and Clinton subdivisions of northern New York and of Pennsylvania, and th,^ to mistake the First for the Second Graywacke of Eatifti, and. in fact, to deny the existence of the former as a great series lying above the Lower Taconic and bel^w the horizon of the Trenton limestone. The brothers Rogers and Mather, forty years since, reasoning from the paleozoic succession as displayed m the Adirondack area, were not prepared to admit that, in a region so near as the great Appalachian valley, the paleozoic segments beneath the Trenton horizon could as- sume a type so unlike the well-known Potsdam and Cdciferous subdivisions of the north- em district of New York, or that these -subdivisions could be' represented in the Appa- lachian area by the vast and lithologically nnlike series of the First Graywacke, which l*ton had already, t6n years before, assigned to its true position below the horizon of the Trenion limestone. Hence came the great mistake in American stratigraphy, the denial by Mather and hip foUowers of the distinctness of the First Graywacke of Eaton, and the assertion of its identity with the Second Graywacke of the same author. So long aa this false position,was maintained, there was a plausible argument to be made for the original hypothesis of the brothers Rogers and Mather as to the age of the Lower Taconic series ; but with the recognition of the correctness of Eaton's view of the First Graywacke. the laUacy of this hypothesis became bbVious. and those who would still advocate it can only ' do so by Ignoring alike the results of strati^aphical and paleontological study for the last generation. •' § 172. The absence from the granular (juartz-rock, the granular marbles and their in- tercalated and conformably overlying schists and argillites of the Lower Taconic series, of the organic remains of the various members of the Champlain division, or, indeed, of any ST r'i^v ^'"^^^ ^"^^^^"^ °^ *^« ^"^^l" quartz-rock already noticed, (§^3) was explained by those who maintained the paleozoic age of the series by the con- . vement hypothesis of a chemical change, attended by.crystallization or so-called meta- morphism, wkich was supposed to have effaced the original characters of the sediments , and obliterated their organic remains. In accordance with this hypothesis, it was'believed that great series of strata might, within short distances, assume a new aspect, not .through any original differences in the sediments, but from transformations wrought in these ^er deposition, in virtue of which, fossiliferous and earthy limestones. losL all traces of their organic remains, could be converted into granular limestones containing, instead, only crystalline siUcates. while ordinary sandstones and argillites might become nucaceous. chloritic, or hombleridic schists, and even gneisses and gnmite-like rocks. *de known, in the rous strata resting ng the n6fr well- rds. The relations the east and south- River, there were stalline sediments le paleozoic strata the correlation of ralization, had al- I existence in the ' than the granit- imilar was found morphic doctrine whatever to the B one hand, and :k region, on the nd subjected to c quartzites and - bose others that er, nothing but ystem, from the 3^raywacke belt, hward through wie, but newer h first, the gen- la subdivisions y, the fact that tzite, which he ke, presented a izy limestones. This general to the mind of agnized), was lOwer Taconic, lar quartzites, lites, presents. I and its great ften remarked ^ns, in certain I it has been y e ie eo np le d lis succession 4 m. These vtews, a devetopmefiTorifie Huttoman school m geology were ai F well known to students, accepted a generation since by a large number of geologists, both *»' •;» ;!( .. ■. ; 7>~r- ■ <■< 140 DR. THOMAS STERftY H0NTON THE I r ((■ rocka are of the samfage ^2^t^^,Tl^l:' ^7- ^7^^ ^"^ *^«* " *h« Taconio morphica,enc,andb7thein'™^:oTi^^^^^ ^''''^'^ modified by .eta- by him a« '. imperfectly Metamorphic rock " Tw Wh \^ """""' ^'^''' ^''^«^'^'^^ York and western New EnglandTnclnTed wT *^\^*"°^ crystolline schistB of New focks, were declared to l^tL'leil^^in'n^ ^" T"^ 7 P'^P^' Metamorphic Respecting these, he asserted thrwhTrT "7« ^^^^^y-^t-ed condition "(J 121). "no well-marked line of ^s^^nTk^^Z'^^f:^^^^^^ - semiWe shade, of differmi™, " M.ik ." ' "^ I^' "''° "^^ »">« ky in- ' older or so-cJled Primrrrie. rfc™. T T'!^ '° **"■"• " •*««°» '° «"»«. "■ New York .nd northern £wJ>,2\^t'T? 'he Primary limestones of southern -re nothing more than ^^iZIn^^tZ:^^"^.^^^' ?' I;"""""-""" "^''' been led to belieVe that thp Pr,'«,o«, i • T "^.^^^ "^^ **»« Champlain division. He had all the changesl^:' tenST^tra^^ lized minerals andl^umCo " Tom *.« TT?' ^^"« «°»««to»^. containing crystll, supposed by him to bTpZ^ic wifh le - "j^^^^^^ o^ these crystalline limesTones. ^ maintain the paleozoic CofTesrlTsT '^^^'r^'^f'^ "^^' ^« ^^ ^--^^* *<> had called Primary gne:fs wL not al^^^^^^^^^ "'^*'''' ' ^^^' ^* ^^-*' ^^^^^^ ^« lyingtothesouthandeastoTtllTX'tS^^ «^ «^«talline rocks New York Counti^. and elre^nriJlIr7rj, ''"'^"''"^ *^°^^ '^^ Westchester and cent rocks of west;rn New X Jan^^^^t ht M^^^ ^ "nothing more than the rocISroLll *^« »°^«^Pbic series, and declared to be agencies and b^r tl« i^t^of ianrc''^ southern New Vork he noticed ho^birlt'^, aggregates." >« In this area of limestones, besides granite, syenite aTZ^^tre the^^^^^ mxca-schists and crystalline as intrusive rocks. serpentme, the latter three being regarded by him § ITS. The doctrine of the Metamorphic school of fn^„ and formulated by Mather was brieflTl f n i ^ ^^*''' '"''^' *« *^«^ ^««med stratified rocks in south^al^em New It / '"^^ ^^^f ^''^ of crystalline doubtfulexceptionof the g^lTb^ I Jr. TIT*'" ''*" ^^^'"^' <-^*^ *^« Wer Taconic series, the S of miZ^l'^I^^^^^^^ '^r'^^' ^"^^"^^« *^« massive granitoid and homblendic gTe^^ w Uh Z^i:"". 1^^""^"*^' "" ^^" " *^« one and the same geological period.Td?~ * ^^^^'^ i^«*a"»ne limestones. aU belong to ;^ksof theOh4laird^:Sn:riW iTt^ "'%^^^^^^^ Sc^s^rSsltrri^^^^^^^^ -^jfT«i^;« TACOKIC QUESTION IN GEOLO&t. 141 I Mather, in his final I that " the Taconio t modified by meta- lowever, designated ine schists of New roper Metomorphic id condition (J 121). ocks come together, ) each othet- by in- dition to these, an if the Hudson, but, sstones of southern homblendic rocks, division. He had ily traced through containing crystal-. Jtalline limestones, ie was brought to t least, of what he nntain belt, whose crystalline rocks f Westchester and led, with the adja- < i declared to be r by metamorphic In this area of 1 and crystalline regarded by him as then resumed ps of crystalline land, (with the y), including the , as well as the les, aU belong to th the paleozoic on sandstone to ntiguous groups ae uncrystalline nsformation, by Vork, 1848, pauim. ? what he called " metamorphic agencies," and the intrusion of igneous rocks, in which cate- gory he mcluded not only the interbedded serpentines, but apparently, under the name of gramtes, much of the granitic gneiss, which characterizes large areas of the region, as well as the abundant endogenous granitic veins,— true intrusive or exotic granites being rare in the region. In Mather's cosmogony there was nothing in the geological sequence, at least m north-eastern America, between the New York paleozoic series, as seen in the Adiron- dack area, and the fundamental Laurentian gneiss which there.underlies it. Consequently all crystalline rocks which could not be referred to the latter, were, unless plutonic, the result of some unexplained transformation of the lower part of this paleozoic column, designated by him as tHe Champlain division. § 1Y6. This hypothesis, extravagant as it now seems, was, during the next few years, accepted by many geological students on the authority of Mather and the brothefs, H. D.' and W. B. Rogers. T^ese latter, in 1846, extended this view of Mather to the White Mountains oTNew Hampshire, and suggested that the gneissic, homblendic and micaceous rocks of this series, since named Montalban, instead of belonging, as hitherto believed, to the "so-called Primary periods of geological time," were probably altered paleozoic strata of Silunan age, including the Oneida, Medina and Clinton subdivisions of the New York system. These observers then proceeded to name many species of characteristic organic forms of theSilurian period, which they thought to recognize in certain crvstalline aggre- gates inib«r&ica-8chists of thertegion. In mi, however, the same observers announced that they no longer considered these forms of organic origin," and, although they did not T'H ^Tu*"^ '^^'^^ *^"'' ^'P'"'"" *^ *° *^^ paleozoic age of the gneisses and mica-schists . of the White Mountains, are known, from their subsequent writings, to have abandoned it as mifounded, though it was for some years afterward maintained, ^ith some variations, by Logan, Lesley, and the present writer.* J 1*11. As regards the ancient crystalline series of the Highlands of the Hudson and of^ew Jersey, which differs in lithological characters from the last, we find that H. D RogJ^re^while he did not accept the notion of Nuttall and of Mather that its gneisses are altered-i)alfij»ala-sediment8, imagined the crystalline limestones, which are really inter- 8trati%d with them, tojbe portions of a younger limestone, altered by supposed igneous ^encies. In the words of Lesley, Rogers, while maintaining the Primary age of the Highland gneisses, "mistook the crystalline limestone engaged among the Highlands for metamorphose^ synclinal outlyers of No. II, as at Franklin." in New Jersey, whereas Cook h|i8 since shown that th^ horizontal strata of this later period overiie the upturned crys- lalline limestones of Fr^klin." As a consequence of this. H. D. Rogers was quoted by Mather as supporting tlhe extreme notions of metamorphism maintained by Nuttall in 182^ which Mather himself accepted, and which, as I have elsewhere said, " were adopted by H. D.^Kogers, as far as regards the crystalline limestones of the Highlands in New Jersey, while he soon after applied the same doctrine, in its fullest extent, to the irreat gneissic series of the White Mountains. '• Amer. Jour. 8oien|||||] i, 411, and v,lie "See, for hiatoricalVH, Hnnt, Amer. Jou Boy. Hoc. fi Bnada, voi. 1, nee, iv^p. X» loe, vol. 1, 84 ; also Aioic Rocto, pp. 62, 181, 182, and Tnuw " UHkif, Amer. Jmr. Sdenoe, 1866, xxxix, ; " Hunt, Aadc Rocks^p. 41. iS^. ■'■P •f « a|^-'.«^u>'^i^^»\^»^'i^^|%*-'J^y;*M ♦«.-. I, / • ^^' . (' Iv [i'^ j i, ■ . i i . 1 1 1 i SS| r 14Si DB. TkOMAS 81;bRRY riUNl^ ON THfi J 178. To sum up in « few words the viev^s of the Metamorphic school forty years since (1840-1846) : we find that H. D. and W. B. Rogers then maintained the paleozoic age of the Lower laconic series, of the White Mountain gneisses and mica-schists, and also of the c,ry8talline limestones found among the gneisses of the New Yx)rk and N»w Jersey High- lands, though admitting the primary ag:e of these Highland gneisse/ Mather, again, while holding, in like manner, to the paleozoic age of the ]Lower Taconic, was not acquainted with the White Mountain series, but maintained that the whole of the ^ei^ses, mica- schists and crystallineAimestones of south-eastern New York, with the possible exception of the Highland belt, were paleozoic, and of one age with the Taconic series. It is worthy of note that on the geological map of the State of New York, published in 1842 "by legislative authority," of which the Southern District was prepared by Mather himse f, there is no distinction of color between the gneissic rocks of the. Highlands and those lying adjacent to them on the south and east, described by him in his final Re- port, m the following year, as metamorphic paleozoic strata. The serpentine of the region as seen in Staten Island, is colored on the map like the adjacent intrusive triassic diabase » but no attempt is there made to designate other eruptive rocks than tlese. § 1-79. In opposition to the views of thia, Metamorphic 'school, there were not wanting some, like Emmons and Charles T.Jackson, who maintained the Primitive age of the whole or a part, of thes6 crystalline^ roeks of New England, though recognizing, as Eaton had done, their lithological distinctness from the gneiss of the Adirondacks, and of the High- lands of the Hudson. Already, moreover, in 1824, Bigsby had discovered, around Lake Superior and beyond, the existence of two series of crystalline rocks, and distinguished the younger of these as belonging to the Transition series. More than twenty years later the Geological Survey of Canada, while adopting for the crystalline rocks of New Engltod and their extension into Canada, the hypothesis of tiieir paleozoic age, reexamined thesd Transition crystalline schists of Bigsby, as seen both on Lakes Superior and Huron, and on the upper Ottawa, and described them as forming a distinct group between the base of the paleozoic series and the ancient gneiss, upbn which it was found to rest unconfbrm- ably. This intermediate series, first described in 184Y, was by the present writer designa- . ted, in 1855, by the name of Huroiflan,— the underlying gneissic series haviug, in 1854, received the name of Laurentian. V ' § 180. In i858 appeared tke final Beport of H. D. Rogelton the Geology ^>f Pennsyl- vania, in which we find no recognition of the extreme dDctrines of metamorphism main- tained by Mather in 1848, and by W. B. Rogers and himself in 1846. Not Ravi^g come to an understanding of the question of the First Gray wacke, H. D.-Rogers regarded the Lower Taconic series in Pennsylvania as an altered form of the Champlam division, and consid- ered the granular quartz-rock ^ith ScoUlhus to be the equivalent of th^ew York Pots- dam sandstone.^* The characteristic crystalline rocks of western New ^land and south- eaetern New York, described by Mather as altered paleozoic, pass beneath the mesozoic sandstone m New Jersey and reappear in south-eastern Pennsylvania. These ro6ka were iy)W,-in 1858, descnbe^y H. D. Rogers as forming two gr eat groups, an older or so-calkd i«d B^J'n^t^^ T*^ "^^^^^^ "** °"^ ««pentme. of thefegion, the pre«nt write^on the Oeolog. ical Htatory of Serpentine^ 1888, Tnu«.Koy.8oc.Can«d^ VOL i,8eciiv,page« 172-174. ^^ '*Jpt^lMm^dis^MJotbapncia^^^va»BM ^ iM^Btimti qcMtrfte »f B wii w y l v iBte and thftlfew -- York Potsdam, aee Amer. Jonr. Science, 1866, xxzix, 223. Vt"rl'\ # V ent wrfte^on the Geoloflr' iniuylvKiiift kBdthbKeW- .^ TACONIO QUIJSTION IN OBOLOGY. .' 143 l77jy^''\7fri'^^''^T^'''''' '^ "y"**"^* .chirt«; which 4 called Azoic 1«^.r^»^ \ ^""'"'^ "^ '^' ^^"*^'" sandstone. The view, of H. D. Roger, m laSfiKS^thregard to th^ crystalline rock, of the Atlantic belt, were thu«. a. I ha3se^ In'^^nT; r^'l'T'^^"'^^'^*""'^"^ ^y Emmons, but were i; direct :>;LT tioh to that of Mather, which had been adopted by Logan and the present writer."- and Tn m7. "^" ' ^'"'*'""' ""*' ^-^^'-'--^ by t>« Messrs. Rogers themselves* • ^^V.fZo "^?'^'" ^'^ *" ^^^^' ^"* ^'^ ^«°^"b^« b'othi William B. Rogers survived till 1882. and fully scared the views set forth by)the former in 1858. as toT TtnX TT "^" . *'*' ^"* ^""^^ "' ^'y«*'^"'^« «"^^-- His careful and extended S r .^""-^'Ti^T^ "'"^ ^""' ^^'^ convinced him of the fallacy of the metamor- ph c hypo hesiH of Ma her. In a sketch of the geology of that state./ontributed by him as late as 18Y8 to Mac aHane's "Geological^ilroad Guide." Rogers maked it plain th^t ^crystalhne rocks of that reg^n are all pre-paleozoic. and older than whit he'ca^l the Pmnal or Potsdam group. This he describes as lying.on the western slope, and in the Zt^7^Zl : 1 ^""l "''^^' " °'*^'^ ^"^^^^'"'^ ^'PP-^ *° the'south-elt. i^ seemmg conformity, beneath the older rocks of the Blue Ridge, but often.^^lso, resi ng un^nform«blyupoa or against them." These older rooks, he lells us. -com^ris; mas es mZ A^^f P "^i'n T" T' '"'''•^"^'^^ '^'" '^"^' "^^^ »»« -f-™« - that the letters. A, B C a^j p, used m h,s,t*bular view, "mark four rather distinct groups of , Archean rocks found m Virginia, of which the first three, may probably be referred to the J^^rentian, Huronian and Montalban periods respectively, and the fourth to an inter- mediate stage.— the Norian or Upper Laurentian." $ 182^ It should here be remarked that this Primal group of the valley of Virginia, also called by Rogers. Lower Cambrian, is^no other than the base of the Lower Taconic series, which he continued to regard as in some sense the representative of the Cambrian Potsdam »f the Adirondack region. In this connection, as showing the relations of this group to the^crystallme rocks, and the apparent inverted succession. I venture to make the following extracts from a letter from W. B. Rogers, written to me in 1S11, for publication in my volume on Azoic Rocks, after an examination with him of some forty unpublished transverse sections, madeacross the Blue Ridge during his geological survey of Virginia In many of these sections "illustrating the position of the liwer Cambrian, (our Primal ^nglomerate. etc..) in their contact with the crystalline and metamorphic rocks of the Bhie Ridge in Virginia » " the unconfor^nity of the Cambrian upon and against these crys- taUine and metamorphic rocks is unmistakable and conspicuous ; the lower members of S^^rih I^ "T.^ T' r^'' '^' ^^^P" ""^"^ ^^^P' ^"»^ north-west undulating ^ onj^e ^ of the steeply southeastward-dipping flder rocks. In other cases, the Pnmal 1^. thrown into south-east dips in the hills whic$ flank the Blue Ridge, are made to underlie, with more or less approximation to conformity, the older rocks forming the r^^^lT^r'^'^l ?"l'**"°" "^^^'^ - '''^^'^^' ^- which thrift 18 retenedte^the letter as published." 1 188. iThile, therefore, the brothers Rogers and others with ihei|i held, and still hold. M-' is,ti^s:s:i^^!'"^ ^C~ -I-* r "^■t- ♦ % 4 .\ .'■'■. • *i«y'i ' li^.td 111 t wf 'n^t r ■ M M '■i^. A ». % DK THOMASl 8THUKY HUNT ON THH to Clio palooisoic age of the hcfwei Tac^nic rocks, th« view put^forwwd by Mather, that the gn^at region of gueisaes and orystalline achistx with linieittlpvH, lyiAg ip the vast o£ th'eae, consiBts of more highly altered paleozoic strata, had become discredited It was, as we havM seen, abandoned by Jf T). Rogers for reunsylvanii, in 1858, and by W. B. Rogers for Virginia, where he recognized in the pr^Ta(X)pian rocks the same great divisions which I had elsewhere pointed ont. The history of the studies of Thomas Macfarlane and my^ own, which showed conclusively the pr^-paleozoic age of the extension of the Ne land crystalline schists into the Province of Quebe«r, has already been told else § 184. It was, therefore, with some surprise that geological students fouQrV|il. fil'iDaiuC in 1880, attempting to resuscitate, in its completeness, the discarded viey(j„of ffl^ti^. Ill an elaborate paper on "The Geological Relations of>the Limestoijj^ 'Beui^ Westtihesirer County, New York," which appeared that year, Dti^na, following up tli^Ppltoning already noticed (§ 16 r), by which he sought to sus^tain the paleozoic A^e of the Lowtrt- Taconic rocks, proceeds to assume that the crystallin^B viarbles enclosed >» the gneisses, as well as the gntusses and crystalline schists of the region teamed, afe altered rocks of paleozoic age. To quote his conclusions : " The limestone of Westchester Comity and of New York Island, and the conformably associated metamorphio rocks, are of Lower Bilnrian age," and, farther,." the limestone and the conformably associated rocks of the Green Moi^ntain re^ou, from Vermont. to New York Island, aro\ of Lower Silurian age.''" His argument in favor of these a8Bumptions,^pears to be briefly thisr that the crystalline lim^stoies of the gueissic series, the grdg|iilr Lovver Tacoiiit! marbles, and the fossiliferous Cambrian aiid Ordovician limestones louud amodg the uii^crystalline sediments of the Appalachian valley, along the western flank of the crystallke belt n9rth of the Highlands, are but three ditferent conditions of one and the same cau;areou8 series, and, hence, that the grpat area of crystalline rocks south of th« narrow range pf the Highlands (of which he admiU the eozoic age) consists of paleozoic Strata, Cambrian or Ordovician in age. § 185.' Dana, having announced his conclnsionk as above, adds : "The evidence which has been adduced, though then but partly disceme^, ledProferisors W. B. and H. D. Roger?, and Professor W. W. Mather, nearly, to the results here r^lached." In support of this asser- sertion, he refers to Mather's repeidt of 1848, in whictt, as we have seen, the hypothesis was advanced, and also, under the head of " ^<>fer of 1841, maintained the Champlain age of the Lower Taconic series, — a view which, as we all are (ware, one of them, some years later, abandoned for that of its Ddv^nian age. These geologists did, for a time, put forward thei vievv (afterwards relinquished) that ^fies o^ the White Mountains consists \ of altered Silurian (Oneid%01inton IpOlath'e^dip his argument, made the most\ of the error of H. D. Bc^rs^ who jfu 1840, ctlpteil interstratified crystalline .limestones among the Primary gneisses <>f Ne^ Jersey for superincumbent limestones in an altered condition, but Dana fails to show th«t the Messrs. Rogers evegr mointaiiied the paleozoic age of the great series of . ^ : __£2 i „ "^Hn nt, Amjc Bockfl,jip.^82r^l88^aiid Amfir^JooE... ' Amer. Jour. Science, 1880, xx, 465. 3cix^27 :ii!i i i I 1. '■"--M • ,4 - ' *»■# j» ^ ^;V5;f^i^ 'T^i^ffff^^'f tACONiO QUR8TI0N IN «feoLO«Y. 148 18 Macfarlaue and my. crystalline TOoir in sonth-iMtern New York, as he woald have his headers infer. When, in 1868, H. D. Rogers h^ occasion, in his final Report on the Geology of Pennsylvania, to dewjribe the continuation of these same locki fnto that State, he djstint^tly assigned them to a horiaon below the base of his paleozoic series, proposing, at the same tone, a Hypozoic and an Arzoio system to inclnde them. '^ $186. The Highland range on the east side of the Hudson traverses Pd^m county, and, passing south-westward to the river, occupies but a small artm in the north-wert cor^ ner of Westchester County, Along its south-east base, at Annsville and at Oregon iB,met a narrow belt of scarcely crystalline limestone, accompanied by an argillite ©r 4lcoi4 slate and resting unconfornfably upon the ancient gneiss. This belt, apparently n Lower tJ conic outlier, is regarded by Dana as partially altered Lower Siluriaa, and'%e grade of metamorphism" is declared by him to become more intense to the smith an^ast, giring rise to the whole gneissic area of Westchester tmd Now York Counties. The gneisses tnd conformably mtetstratified crystalline limestone* of this large area ate, as we hm^ seen supposed by Dana,tp be metamorphosed Lowei Silurian, though they are red^ ifndia' tmguishable from the rocks of the pldjacent Highland range, which 1^ admits to^|^he.t| or Primary. In support of his startling propositij^n, Dana might be expected «. „t out some distinctions between the rocks of the two arms. He begins by suggesting .ertiin differehces as to more or less micaceous or hornblendic gneisses in the two regions i&Qnes- tion, but confesses that "there are gradations between the two, in both respects^hich make the application of alithological test very perplexing," and admits that "the litWog- .ical evidence of diversity of age is weak," » a Criticism which the intelligent reader will conclude is equally applicable to Dana's stratigraphici^l argument. I am'Tamiliar with the Tocksof many parts of Westchester County, and since . the publication of Dana's paper in T880 have taken repeated opportunities to examine, in various localities, the roc^ called by him Metamorphic Lower Silurian,' as at Bingring, Tarrytown, Yonkfers, Spuyte# Duyvil and Kingsbridge, along the Hudsoju' I have also studied the same rocks farther to the east, along the River Bronx atfd thS^Hariem Railroad to Pleasantvale, as well as between this line and the Hudson, and have crossed eastward to Ung Island Sound and examined the exposures on the shore at and near New Rochelle. Being already familiar, with the Uurentian rocks throughout Canada, as well as in parts of the Adirondacks, and in the ? u ^M ^™ ^''^"'^ ^°""*^' ^^"^ ^**''^' *^'°^ff^ New Jersey and Pennsylvania to the Schuylkill and beyond, I do not Hesitate to say Ihat these gneisses and thc^ associated crystalline limestones of Dana's so-called Metamorphic Lower Siluriap. in Westchester Cx>unty, cannot be distinguished from the typical Laurentian: I believe that the judgment of aa imparUal observer wojald be that the notion of any difference between the Laureh- tiaA gneisses and limestones of the areas mentioned, and the gneisses and their intejstrat- iHed limestones of Westchester County, has no foundation in fact. $'18Y. Passing now from Westchester County to^ the adjmcent Manhattto Island, the same Laurentian gneiss is seep in it» northern pprtion, between Seventh and Eighth Avenues, eiqjedally in a cutting at One Hundred and Forty-fifth Street, and thence in a ndge some distance farther south, the strat» being i^early vertical andbf grayish hom- ■ Aiiwr. Jew. Hdsnoe, 1880, xx, 8W. Sea IV., 1884. 19. m '^■'^.^'- /S., -tr f^e l)|i, THOMAS STERRY HUIIT ON THE Kb ti. i UM . blendic gneiss, and a -band of crystalline limestone appearing a little farther to the east, on Harlem River. A^ quarter of a mile to the west of this ridge, in Mount St. Vincent, is^epn a distinct type of highly micaceous gnejss and mica-schists, and similar rocks are exposed at intervals in the western part of the island, as far south as- Fifty-ninth Street. Farther eastward, in the southern part of Central Park, just above Fifty-ninth Street, the • numerous rock-exposures are all of similar mica-schists and micaceous gneisses, often at moderate angles. They include endogenous granitic veins, occasionally presenting in their structure a marked bilateral symmetry, and sometimes transverse, but at other times interbedded. Several perched blocks here found are of similar endogenous granite, and are apparently boulders of decomposition, left in the subaerial decay of the rocks of the region. These micaceous rocks are unlike those of Laurentian areas, but, on the contrary, closely resemble those of the White Mountains and of Philadelphia which I have called Montalban, and are like the younger gneissic series of the Alps and the Scottish High- lands. I, therefore, as long ago as 1871,* noticed these rocks as belonging to this younger series, and have since expressed the opinion that the Laurentian "of Manhattan Island apipears to be overlaid in parts by. areas of younger gneisses and mica-schists, the remaining portions of a mantle of Montalban." " It is, however, by an error for which I am not responsible, that in Macfarlane's " GTeological Railroad Guide," in 1878, the Montal- ban of Manhattan Island has been represented as extending qpward along the Hudson River Railroad by Spuyten Duyvil, Yonkers,, Tarrytown and Singsing, as far as Oroton, before meeting the Laurentian of the Highlands. There appears to be, however, an outlier of Montalban rocks at Cruger's Station, just above Croton, and there may be others in various parts of Westchester County. * ^ § 188. It has been deemed necessary to notice thus at length, in this connecti9n, Dana's resuscitation of the ancient views of Mather, for two reasons : first, because thereiA, both the Lower Taconic rocks and various crystalline rocks just noticed, are stlpposed by him to be contiguous portions of ^e same CambriMi and Ordovician (Lower Silurian) sediments in different stages of transformation ; and secondly, because the manner in which the names of the brothers Rbgers are cited to Dana in conjunction with that of Mather is such as to lead the reader to the false conclusion, that those eminent geologists supported Mather's hypothesis of 1843 as to the Cambrian and Ordovician age of these same crystal- line rocks, as well as of the Lower Taconic series ; which latter view, as we have shown, W. B. Rogers repudiated a few years later, in 1851 and again in 1860. § 189. The rise and fall of the doctrine of regional metamorphism, which is but an extravagant developmenfr^of the Huttonian hypothesis of the origin of crystalline rocks, forms a curious- chapter in the history of geology. I have elsewhere related the early application of this doctrine to the crystalline rocks of Mont Blanc by Bertrand, about llQI, and its subsequent restatement by Ke^rstein in 1824. until it was taken up and popu* larized by Lyell, Murchison, and various continental geologists, so that the view became generally accepted that the gneisses and mica-schists of the Alps are but altered secondary and tertiary strata. The story of the refutation of this hypothesis for the Alps by the =4«7r • President's AddreBS before the Amer. Assoc- Adv. Seience, 1871, in Chem. and Geol. Essays, pp. 248 and ' " Smithsonian Beport for 1883, .Ai*,!./-, (Sft^rJuc^.'jiriii.j.^i <.»w4iaSi)^iS|-'!4ii. .!..■■» vrfe^tfe^lNik • * -t' ^\i^-1^'' SJl-*^^- TACONIC QUESTION IN GEOLOGY, 147 d Gaol. EBwyg. pp. 248 and!' studies of Favre, Fillet, Gastaldi and others has also been told .« A similar view was extended to crystalline rocks in other parts of continental Europe, in the ^ritish Islands and in eastern North America, save that for all of these a paleozoic age was generally assigned. The opinions of Mather on this subject were adopted by Logan and others including the present writer. The brothers Eogers, in 1846, advanced a similar view for the rocks of the White Mountains, but abandoned it before 1858. It was not until ISW and ISYl that the lyesent writer, rejecting entirely the views of this school, asserted the pre-Cambrian age of all the great areas of crystalline rocks, alike in North America and in Europe. Nearly coinciding in time with this, came the independent action of Numerous continental geologists, including those already named, and the result has been such an advance of the views of the new school that, in 1881, Callaway could say that "every case of supposed metamorphic Cambrian and Silurian has been invalidated by recent researches," and in 1883, Bonney, now President of the Geological Society of London, wrote that the hitherto accredited " instances of metamorphism in Wales, and especially in Anglesea, ili Cornwall, in Leicestershire, and in Worcestershire, have utterly broken down on careful study," » as had already been the case in the Alps and in North America. § 190. The last stronghold of the metamorphic school in the British Islands was in the north-west of Scotland, where Cambrian and Ordovician fossiliferous sandstones, limestones and shales, resting upon the ancient granitoid gneisses to the west, are towards ^ the east oveilaid in apparent conformity by a great series of unlike gneisses and mica- schists, whiph form theScottish Highlands, and were declared by Murchison and Archibald Giekie, from their stTiaieTto consist of still newer rocks in a so-called metamorphic condition. The structure of this north-western part of Scotland was in fact, according to their teaching, the precise counterpart of that of New England as formerly taught by Mather and his followers, and still supported by Dana. The late Prof Nicol, however, constantly opposed this view of the structure of the Highlands maintained by Murchison and by Giekie; while the present writer, from his lithological studies of the Highland rocks, declared in 1811 his conviction that the upper gneisses of " the Scottish Highlands will be found .... to belong to a period anterior to the deposition of the Cambrian sediments, and will correspond with the newer gneissic series of our Appalachian region," "* then described as the White Mountain series,— an opinion which was reiterated, after farther examination of thQ.rock8, in a communication in 1881 to the Geological Society of London, when these Highland gneisses "were designated astMontalban.** § 191. The studies by Hicks of the geology of parts of this region from 1878, and the later and independent ones of Callaway and of Lapworth in other districts, had already, in the beginning of 1888," shown the fallacy of the views maintained by Murchison Ld Giekie as to the geologica l structure of the Highlands. The united testimony of these " Amer. Jour. Science, 1872, iii, 9, and Chem. and Geol. Ewkyg, pp. 338-342 and 347, 348. Also farther Trana. Roy. Hoc.. Canada, vol. i, sec. iv, pp. 182-196. ' " Callaway, Geological Magazine, Sept 1881, jk 423, and Bonney, ibid., Nov., 1883, p. 507. Hunt, President's Addiw before the Amer. Assoc. Adv. Science, 1871, and Chem. and Geol. Essays, p. 272 " Proc. Qed. Soc., ]x>ndon, in Geological Magazine, 1882, ix, 39. n^J'^^t!' ^- <^^J«»'' "78, xxxiv.. 816 ; GeoL Mag., 1880, vi ; also Quar. GeoL Joor.. 1883 (with appended^ ^Z;^; *^.k''^!J1!!' T;^I ' *'"" '^''•'"'^ "^ ^ropes^he Metamorphism, ibid., May, 1884 ; and summaries to aooonnta of the Progress of Geology in the Reports of the Smithsonian Inst for 1882 and 1883. % tkf .il ^ilnS^-^iii >t< .f^ /6..X. .'.^1, -^ J.'. . "-ife-'.'-* I 1 ■^i- ! 148 DE. THOMAS STERRY HUNT ON THE observers made it clear that in the rej^ion in question were portions .of two gneissic series,^ an older or granitoid gneiss, like that of the western coaa't, and a younger, very distinct in type, which has been variously designated aa Upper Pebidian, Grampian and Caledo- nian, and is that described by me in ISH, and again in 1881. as of the White Mountain or Montalban type. This, the younger gneissic series of Murchison and Giekie, was clearly established to be of great thickness, and older than the fossiliferous Cambrian, which it is brought to overlie by |serie8 of great folds, overturned to the west, and acc6mpanied by parallel faults, with upthrows on the east side, as shown by Hicks in Ross and Inverness shires, as well as by Callaway in Assynt, and by Lapworth in Eriboll. 5 192. The concordant and independent results of the eminent observers just named having thus demonstrated the fallacy of tjie views of Murchison and Giekie that thb gneiss which in the Highlands overlies th^ fossiliferous strata, is a still younger paleozoic series in an altered condition, the Geological Survey of Great Britain, of^which Giekie is now Director, undertook in 1883 and 1884, a re-examination of the tf^^ in question. The result of this has completely disproved the former statemeiits^^urohison and Giekie, and has confirmed those of the new school. The Director of*.tfe Geological Survey! in a note very recently published,'' tel^s us that he has "found the evidence alto^ , gether overwhelming against the upward succession, which Murchison believed to exist in Eriboll. from the base of the Silurian strata into an upper conformable series of schists and gneisses," and adds : " That there is no longer any evidence of a regular conformable passage from fossiliferous Silurian quartzites, shales and limestones upwards into crystal- line schists, which were supposed to be metamorphosed Silurian sediments, must be frankly admitted." The same conclusions are also reached by Giekie from the re- examination of the similar sections in Ross-shire, previously described by himself in accordance with the views of Murchison. . The preliminary Report of the surveyors, Messrs Peach and Home, which is sub- joined to the Director's note, shows the same structure as was already described by the late observers, namely, overturned folds and great faplts, with lateral thrusts westward, by which the gneisses are made to overiie the fossiliferous strata,— the horizontal dis- placement of the gneisses to the west, which are superimposed on the Cambrian rocks, being, in some cases, according to Giekie. not less than ten miles. § 193. Giekie notices the distinction between the older or granitoid gneiss, portions of which also appear in the Highlands, and the upper gneissic and mica-schists series, the pre-paleozoic age of which was shown by the observations alike of Hicks, and of Calla- way and Lapworth. He calls attention to the laminated and schistose structure developed by the great pressure and friction along the lines of movement in gneissic and homblendic rocks, and also to similar changes produced by the same agency in detrital rocks, such as arkose. Both of these structural alterations are apparently included by Giekie under the head of what he calls a "regional metamorphism,"— a misapplication of the term likely to confuse the reader, since local structural changes, induced by mechanical movements in ancient crystalline rocks, have nothing in common with that mysterious process which has been supposed by the metamorphic school to generate similar crystalline rocks from uncrystjOline sediments. As regards the changes wrought by the same agency on detrital " Ni^are^ Not. 18, 1884, xxxi, 22-86. n^..Ut w.a^#iT.«»„i.« II i m. «»"'«. "ogers a« to the fflimM^wtwtAa Tx- — f - ^-^^ ""■■■°t'''^gyv"'yg™c K , a nn tn e latet ooneluflton a^f W^B . K og ew a mrtm I. i»^^w"V^i,~i' . %aLb «', 1 ttA^Mt.^^ I, , 180 KR. THOMAS STBRBY HUNT ON THE Transition by Maclure, includes the Primitive Quartz-rock, the Primitive Lime-rock, and the Transition Argillite of Eaton, and is the Lower Taconic of Emmons, and the Itacolumitic group of Lieber. This series, which I have preferred to call Taconian, is essentially one of Transition crystalline rocks. The quartzites, which predominate in the lower portion, contain much detrital matter, and are sdmietimes conglomerates. They are, however, ' often vitreous or granular, the latter variety being sometimes flexible and elastic, and - constituting what is called elastic sandstone or itacolumite. These quartzites, like the limestones of the series, often contain an indigenous micacepus substance, which is in most cases a hydrous muscovitic mica, related to sericite or to damourite, A similar min- eral predominates in certain layers of soft unctuous lustrous schists, which, from their aspect, have been called talcoid or magnesian, and are found intercalated alike with the quartzites and the limestones of the series. The latter, often more or less magnesian, are generally finely granular, and yield marbles for statuary and for architecture. They are often variegated in color or banded with green or gray, constituting cipolins. The min- eralogy of the limestones and their associated crystalline schists, has been noticed in §§ 51, 65, 68, 76, "79, and it has been shown that the Taconian is an important ore-bearing hor- izon, including, besides great deposits of magnetite, others of siderite and of pyrite. Both of the latter species, by epigenesis, give rise to hydrous iron ores, which, throughout the Appalachian region, characterize the outcrops of the series, and are generally imbedded in clays, the result of the subaerial decay of the enclosing schists, which, it may thence be conjectured, include, in many cases, large proportions of a feldspathic mineral. The argillites of the Taconian, often yielding roofing-slates, are interstratified with more or less silicious beds, and occur chiefly in the upper part of the series. The mineralogy of the Taconian has been further discussed in the author's essay on " The Origin of Crystalline Rocks " in the Transactions of the Royal Society of Canada,* Vol. II, Sec. Ill, p. 63. ' § 197. These Taconian rocks are not confined to the Appalachian valley. Extending southward therefrom, they are traced in 'Pennsylvania along the eastern base of the Blue Ridge into North Carolina, and' are found in outliers to the east over the Atlan- tic belt from Georgia to New Brunswick. To the west of the great valley, they are known'to underlie the eastern part of the paleozoic basin, and appear in eroded anticlinals from beneath the coal-measures, alike in Alabama and Pennsylvania, where they are directly overlaid by Ordovician strata. They are seen in similar conditions, lying un- conformably beneath the Ordovician limestones of the Ottawa basili, in Hastings County, Ontario, and are believed to be represented l?y the great series of argillites, quartz- ites and limestone^ around Lake Superior, which, in 1873, I called the Animikie series, and which there underlie, unconformably, not only the Cambrian (Potsdam) of the Mis- sissippi area, but, according to Irving, the Keweenian series also. The presence of Lower Taconic rocks was long since asserted by Houghton in the northern peninsula of Michi- gan, and it is probable that a part of what has since been called Huronian belongs to this Animikie or Taconian series (§ 89, 90). The argillites and' quartzites which, in the Black Hills of Dacotah, intervene between the older crystalline rocks and the Cambrian, resem- ble those of the Taconian. $ 198. The Taconian series is not destknte of evidences of orgsmic life, but contains, -*B UX9 grtUiliUAr (£iuutaul>ctt UOttX IW UlwiOj^inp typitjaa o CWt i ffW * »lllwm ft» Pimy pffitBiiB ' MHP OTIIf K * out the Appalachian valley. Similar markings in the silicious beds of the series in Hast- 'ii I' H- >iik ■" *^A ^£ . ^1/ \ "'^^'^fiff^'' ""■ '.d TAOONIC QUESTION IN GEOLOGY. ISl mgs County, Ontario, have been noticed as probably worm-burrows by Sir J. W. Dawson who has also described the Eozoon Canadense found in- the associated limestones, while the' Ti^ r.r """/'^''''^ *' ^^^ ''"^«' ^'""^ th« western end of Uke Superior have itlbtti^LT^Tn ''"^" '^'^^ '^'^°""°' " ' ""'^^ ^^^^-*«^> ^-y --"iute a Imk between the older eozoic groups and those of paleozoic time § 199. The Upper Taoonic group, the First Graywack, of Eaton, the Potsdam and Quebec groups of Logan, {which include a large part of what was described by Mather and by Logan as Hudson River group,) we have seen to be the Appalachian representative of the Cambrian period. It sometimes overlies the Taconian, but, in the absence of this rests directly upon the older crystalline j^oups along the eastern border of the great Ap-' pal^hian basin. Unlike the Taconian, however, it does not, so far as known, exfend eas^ Wtt A?" T: r^'^%\*^« ^««t' - ^« re'^ede from this border, it is soon replaced by the Adirondack type of the Cambrian. This Appalachian Cambrian series is wholly uncrystalline, and is separated from the distribution of the Cumbrian and the Ordovician in eastern North America, there was evi- dently another great stratigraphical break, with erosion, followed by a considerable conti- nental depression, which preceded the deposition of the Ordovician limestones. Similar disturbances seem to have intervened at the beginning of the Silurian period in this east- em region for we find the Silurian limestones resting directly upon somewhat inclined and eroded Ordovician strata near Montreal, and, apparently, also in the valley of the Hud- '^!^ i /r^ "''* *^^' '"'*''■'' ^""'^^^ *^« ^«** mechanical sediments of the Oneida. Medina and Clmton, which to the west of the River Hudson constitute the chief part of the Second Gray wacke of E.ton, at the base of these limestones, are *t,parently absent - a fiu, pomf ing to the emergence of this eastern region during the early part of Silurian time The local disturbances which at this period prevailed in the eastern part of the great basin' are farther shown m the conglomerate character of these Silurian sandstones in parts of New York a^d Pennsylvania, though it should be noted that in these regions, as well ^ OnS TL, ' ??fr *° ^' "" '"'^^'^'^"'^ succession from the Loraine shales to the Uneida, Medina and Clinton subdivisions. of fhlT' A' l""'",!* °^ *"" *^''' ''*"°"' movements which affected the eastern border laii hv r ''l"^ T ""l ^""^ *^'* '^' '^^'^^^'^^ '' '^''' '^ -«^« P-^t« directly over- ^es\ r "*°';\f '" ^^ '"'•^""""•^ ^*™*"' "^^ '^ P«^«- '' ^-Id seem, by lime- tllHn *^"'^ P""^^ "« "^«^ "'• !««« involved with each other, and with still older crys- to IfflT^r;, ^ IT''"''' movements of folding and dislocation which continued to affect the Atlantic belt at intervals until after the close of paleozoic time. From the tTn 'f f f ^'*P^^^^ '^''^"^"^ ^hi«h have thus resulted, various observers have,aurinff the past forty years, conjectured that the Taconian limestpnes are strata of Cambrian of SZlLe'dSIate^' ''^ "'' ^^^'^'^^^ -n^fossiliferous marbles, often holding w!!^^?^^^.^"-''''^'''^ "! "!* ""^y in c ontradiction with each other, but, m TJ^**^^"^^ and are, moreover, baaedT f upon the unproved and now generally discredited hypothesis of progressive and r^ional V ' «,<»'»« -^ 152 BR. THOJLA.S STBtlltY HUNT OK THE I ; ' \ fi. li ! M ! ^ I metamorphism. This hypothesis, as long since maintained by Mather for the rocks of. eastern North America, and later by Dana, asserts successive changes,— called by the latter "grades in metamorphism,"— from nncryst'alline sediments through the Taconi^n and , other more njafssive crystalline schists to the granitoid, gneisses. These various and dissimilar groups. of strata, as I maintained in 18*78, and as will to-day be admitted by nearly all geologists, " are not the result of different and unlike changes which one and the same uncrystalline paleozoic series has suffered in different geographical areas, but, on the contrary, belong to successive periods in paleozoic and eozoic time. Thd great divisions of the latter . i , . present in ascend^ing order a progressive change in mineral character, the nature of Iwhich has been shown ; .... thus constituting a veritable passage in time from the! granitoid Ottawa gneiss at the base of the Laurentian, through the inter- mediate Hurqinian and Montalban divisions to the less markedly crystalline schists of the Taconian."" , Such a succession, I have since endeavored to shew, is the necessary result of the seculir process by which, from an undifferentiated primeval chaos, the various groups of Pr|imitive.and Transition crystalline rocks have been generated, as set forth in the crenitic hypothesis" already noticed in § 194 of the present essay. ' § 202. The Taconian crystalline rodks were deposited over a large part of eastern North America upon ihe eroded surfaces of more ancient eozoic groups, and in their turn suffered greatly from movements of the earth's crust, and from erosion, previous to the beginnijig of Cambrian time. Over the more depressed jiortions of the worn surfaces, the uncrystklline sediments of es^brian, Ordovician, Silurian, and later periods, were next succesjsively laid down, alike on the Taconian and the more ancient crystalline groups, not j however without intervening movements of the earth's crust, which along the eastern portion of th.e great paleozoic basin caused stratigraphical breaks, foldipgs, and partial erosions of these later groups of sediments. Beyond the limits of this basin, to the south abd east, the sparse distribution of areas of paleozoic sediments, and their absence from the Ijigher levels among the crystalline rocks of the Atlantic belt, permit us to suppose that the paleozoic seas dirl'not invade these higher regions ; while the deposits made by some of them at lower levels among these same crystalline rock§^ have been in great part removed by subsequent agencies. As a, final result of this process, we find, within the great basin, the Taconian rocks resting on various older crystalline groups, and themselves overiaid directly by Cambrian, by Ordbwcian and by Silurian, while out- side of the limits of the basin, areas of the same Taconian rocks are in parts overiaid by mesozoic and by tertiary strata. ^ . - . ' § 208. As regards the existence in other lands of a similar series of rocks to the Taco- \ nian of North America, we have seen that Lieber, whose independent and careful studies \of this series in South Carolina we have resumed in Chapter IV (§ 69-T9), supposed them to be the stratigraphical eqt^ivalent of the Itacolumite or diamond-bearing series of Brazil, i ♦' Hunt, Aa)ic Rocks, 1878, ^. 253 ; see also ilnd., p. 210. \ *' " All physieal theories properly so-called are hypotheses, whose eventual recoghitioli as truths depends upon their consistency with themselves, upon their agreement with the canons of logic, upon their congruence with the facto which they serve to connect and e*i.lain, upon their conformity with tfce ascertained order of Nature, upon the tectent to which tliey approve themselves as trustworthy antic ipations or previaiona of facta verifie d by anbee- -littent observation or experimeht, and finally, upott tTSfflinipirdtjr, or nilEer tbeir i^uciM poww;*' StiSto fiT Concepts and TheorleBofModemPhy8ic8,p 86. ^ ■0^^" i-^ 4 ^ 'Mil ^l if o .JKtHie i^'b, J ^fal J^v. ^■^I'l.^V a^V3 ^ !U„.-^>»i^-4^^*ii " , ' ^ ' - > <-^ S i v'«?%«Jl(^(«f¥ TACONIC QUESTION IN GEOIiOGY. Thes^ diamond-bearine rocks in BundelJchand have since beei described hv fK Geological Survey of India as the Low.r Vindhyan series" T^e LdTes of h^h of I (Jorceii, and of Derby have thrown farther liirhf nn +1,. t* 1 •. '/"°^«8 oi aartt, of in g,..t part of ,4«..ite,, often granXLT^rle tat 1^^^^ '.'"'' °T"" H"»t, ^ntdninghyd^n. mica.'^Zmo andT^rWsst;2^!hfr'- '"'"'* dippmg schistose b^^f the Itacolnmite group « ^ ^ ^ '*'*'^"^- L. I ^^^' ^."]f-«««"bJ«'i«« between the older rocks of Brazil aid those of Gni..« [has been pointed out by Jannetaz who as remarked hv fVn^K < uJ ^ ■also been observed by Schomburi?k"« W^rfKow ^T .1 "acolu^ite of (Juiana has Lnoco. we ..ta/reat det^tnt ofrsi^it^er 'c^^^^^^^^ Uoml Cordil^S Ve^zle a^^^^^ sea from Caracas ea«t^%rd. and is known as the Jad. which have an allkude ots OoIfL? I, /' '™: *^' '^"*^"" ^^""*^^"« ^^ Trini- -.0. -sesemi.c:;:Sai^'rt^t^rM2*^ Uea dans lea do;, ho^fsphL^ 8^^^?"™ ^' v"* 'T "'"' " "*"' ' "^ ""°'^'^*' «■--««* de« i,LeipBig,1861. ''**'*™'^*''*'^^'P- 212. and Zerrenner, Gold, PlatlnmidDiamantWaechen. "aTtrbv'^^ ™ "' India Medlicott and Blanford. i, pp. xxi. and 6».92. l7 17« 7 • ^' ^ Diamond and the Itacolumite Bocks in Brazil 1881 and 1882 A™ t a- 17, 178. and xxiv, 3*42; and in abstract. Bep. Smithsonian Inst 1882^5.4 / !i^ ^' T **""• ^'^"'*' **"'' Ite., BuL 8oc CMol. de France 1884x11 sST ^1 ' '^. '*^^'**'*'^'««"'«'»*<*«8l)iamantB, ' .nbrian ; Gorceix thinks it m^'y rHnSiia^ ' "^'^ *'^ '**"'^"'^'« «~»P ^'g^* ^ ^IterS uCnl^S^^L^rr^rrTnilt^^^ ^---> Histo^. X, 4«5, .^ hdescribed atg«at«r length. and the «3f fhTT^oS an^Yh '' '^""'"^ ^'"^""^ '"^ ^"''^"^ M South Aniarica are well bro,«ht ont Se^t an an^rsroTtT^ "'°" '"^'"''* ^"^^^^''^ ""«« ^ ^orth M fcl b U 88g,i »3 a »8 3&^- '^ r''"'*"'*'y""<'^theggJTO.j « j era ,^^^ Sec. IV., 1884. 20. n ,.^58^^ A.-^j»^"» .T\^ :>jfe^- ' •,! ii I' f«. tifi'i^-, T^S vjii>'p^ir^fi,\Tf0>p^w^^W^?' wff^fi'^ 184 DR THOMAS STBBRY HUNT ON THE some twenty years since by Messrs Wall and Sawkins,'^ by whom they were designated as the Caribbean group, more recently by Mr. R. J: Lechmere Guppy, and in ISIS were examined by Crosby. § 205. The structure of the Northern Mountains in Trinidad is monoclinal, high southerly dips being universal. The thickness of the strata exposed is not less than 10,000 feet, included in three divisions : a lower consisting of a quartzite, granular and usually more or less micaceous, followed by and alternating with hydrous micaceous schists and argillites, often lustrous ; a middle one of several thousand feet of crystalline limestones in massive beds, varying in colour from white to nearly black, and often some- what micaceous ; and an upper division consisting of several alternations of argillites like those of the first, frequently graphitic, and often passing into hydromicaceous schists, with layers of quartzite, sometimes detrital, and, towards the summit,, thin beds of limestone. The whole succession, according to Crosby, strongly resembles the 'Taconian as seen in western Massachusetts. Overlying unconformably this ancient series, which api)ears to be unfossiliferous, is a dark-colored compact fossiliferous limestone, with interbedded shales, in which, among many obscure forms, Guppy recognized Murchisonia Anna and M. linearis, both found in the Calciferous sand-rock in Canada. § 206. Subsequent observations of Crosby,^ in 1882, made in thp mountains of eastern Cuba, between BaracOa and the southern coast, show that there exists to the south of the dividing ridge a belt six or eight miles wide of highly inclined strata, having an east and west strike, and consisting of hydromicaceoias and chloritic schists with immense beds of white crystalline limestone, often micaceous. This group is entirely distinct from one made up from fissile slates, soft sandstones and impure earthy limestones, found chiefly on the northern elope of the same mountains, and regarded by him as probably equivalent to the cretaceous and tertiary strata of San Domingo and Jamaica. Of the first named group he says : " These rocks bear a strong resemblance to the Taconian system of western New England, and are essentially identical with the great series of semi-crystalline schists and limestones pf Trinidad and the Spanish Main, which I have elsewhere correlated with the Taconian." From the published accounts of the geology of San Domingo and Jamaica, Crosby conceives that these islands have a similar structure to that of south-eastern Cuba. Their crystalline schists which, according to him, have been generally confounded with the cretaceous beds, he believes to be like those of Cuba, and of Taconian age. Cleve, in 18*70, noticed in Porto Rico, Santa Cruz and the Virgin Islands an unfossiliferous series which he conjectured might be metamorphosed cretaceous. These strata, which are verti- cal, or have a high northern inclination, consist chiefly of argillites and crystalline lime- stones like' those of Cuba and Trinidad.^ § 20*7. There exists in the Alps, besides the ancient or central granitoid giieiss (Laurentian), the great pietre verdi series proper (Huronian) and the younger gneiss and mica-schist series (Montalban), a fourth great group,'very widely distributed, made up in " Wall, Geology of Trinidad, etc., 1860, Quar. Qeol. Jour, xvi, 660. . '' ■ ^ " W. 0. Croeby on the Probable Occurrence of the'Tttoonian in Cuba ; Science, December 7, 1883, p. 740 ; also in abstract in Beport of Smithsonian Inst for 1883. ** P. T. Cleve, KongL Bvenska Vetenskaps-Akademiens Handlingar ; Bandet 9, "So. 12. The cretaceous age of "the crystalttne BcblHi^ and Umestonerof 8sn llomlngKrww miihtiiipd 1^ >^nj:^^t:ll7:T^:;,Lnl^:^^''- r Summary of Contents. PART II. * ■ •to Lower laconic lin,e8to„e8.-142, 143. MaU^ertTw^o^'^i T ^"'^^*'"'''''"*^^ ^tated;theRed8and-n.kofVemon..-145 ?rAd.»s^^^^ '^'"'"°'"'' ^«^ . the Lower laconic as (Upper) Silurian and Devoni«.^i4r^ J!' f T" T """ ^^ ^^"^'^ «"*» Taconic.-147. Silurian outiie™ near Mont^al an^ Hulf N^w yl^ « Tannic in Vennon^l49, 150. Logan on Lower '^^T:^^^^rlt:rX^ZZ m J rT ''^ , on Tacon,t.-162. Marcou on Upper and Lower Taconic; Silurir^anZnes^rv ^ *"^ to the Vemont Sand-rock; the Ix.wer Potsdam of BimngL -JaZn^H^r J^^^ - / Ford on Lower Potsdam in eastern New York -156 Its Sat^on to th« T^ .", " *^"P ""^^ s^-157. ix^an and BiHingson f.uits, r.^I:lJr^^:l^^'::ZtZ' tS^"" d ■ DwiRht on Cambrian and Ordovician in Duchess Countv-lBfl T n n ." «TOup8,-158. Dale and 161. Emmons in 1S42 on Taconic lin^esto^s? Td tT^ ^mmenUh^rrn -1^2 ^^TlTTr''''' to the age of the Lower Taconic lim^stonea.Joa The fifth and ttiScei-lW^Jl^^^^ IT" " the views of Mather and Logan ; of Matlier and H. D Bo«,r8 i«; i*^ t rr ^^^^^^ »»tween . lachi^ valtey ; absence of^e U^per '^::^^^^^;':ITZ^::^:T''C^'^. ^^T criUciBed.^l6a The mistake of Mather and H. D. Rogers exp^in^Tlirn, Jw^;^ ^Ir^n progressive metamorphism.-170. The I»wer and Upper Taconic ^mna^hS!)!*!" , ^^. ^ -171. The Second Graywacke.-172. The metamorph^yp^'sT^^. ,! «« Champlam division. Mathe..met^o,hicvie\disc^ited.-lS4.XD.^lirm:ta;nr^^^^^ ir»Birr6Ia.KecES^es8urlesT^^^^ Mie/l882; 4to.pp.828. '^-?V. r \\ 1.' '^'■'sv ^.y^rx^.; tf^f-^ I'AOONIC QUESTION IN GBSOLOGY. 187 "I!^ Hi* cltaUon. of Memm. Rogers.-lSfl. Studlea in We«ch«iter Qmnty ; the rock, chleflv L.n«,ntUn -187.Gnei«e. and mica-«chi«ta of ManhatUn Wand de«,ribed.-18a W. l^men" « Ji^ J!^^^^ .TiS" ^ ^' ekie and hia'aMiatanto; the viewa «f Murchison di8carded.-193. Giekie's ao- called metamorphiam criticised.-m. Origin of cryaUlUne rook. ; the crenltic hypotheai^ >CnAPT« If/-C^«^ of fc„owledge.-196. The Taconian chan»cteri«xi ; it. mineralogj^lOT It. di.tr.but ion m North An.erica.-198. It. relation, to organic life.-199. The Upper Ta«,nicorXl 1 th"tL*1.';: f r ^^f "'" "^ «"»"— 200. Relat.?n. of all the., to tZT^LZI^XZ Trin,dad.-205. 0«iby on Tacon.an in Trinldad.-206. In Cuba. Janu^ipa and San Donjingo -207 Luatrou. sch..t. of the Alpa-208. He«ynian clay-alate gnH.p; iZian n^k. in N^a^-2W* Studie. of Barro.8 in 8pain.-210. Apparent wide spread of the Taconia., .erik f * ] •l^~?,ni*!n„°\'*'^**''*''' ''^ ^""^ S^^"^ ^^ * 1^5' "^d tho»« Of »ieWe and his Msistants inj 192 198. have been published since this sec6nd part of thepresent pape was presented m May. 1884. , ^ ^ \. .4 X , ;-''f' V, 1 ''% ,a^in. s<-!:i ••■•.' . <^l ^-^ •*» c :. < ^"' ^ ■ ■ k jm V r , ' * 1 ■ ■ ^ . a J ■ w /^■^.- " ^ ■ ■ L '^ y. - \ w ^ ' 1 ■ ■ m k^* ^ ■ ' ««t3 .*^ y X f - \ \ ^ » f « -•» -tf ^ « \ ■ '- ^ r - i- « • ,»^ ^ ^ '% __ . « _^ gH4^^ ^^^g^ ^jSA^^ mad - *i • -i_ ,-,— — -^-JU -^■i-T -^ '». '■ ■■ ^& _ MM - I _ — ' .. 4 ^^ ^i2^^^^ 1^^^ 1^^^^^^ 2^j| m^^ ii v> iSt'