JMAGE EVALUATION TEST TARGET (MT-3) 1.0 ■f IIIIM i^- m 1136 [25 III 1.4 III |Z2 1.6 .^?/ ^^^ 'c-1 c-: e^' A ^^ -^ :^ o;^ /!Si Photographic Sciences Corporation 23 WEST MAIN STREET WEBSTER, NY. 14580 (716) 872-4503 L

ivi)c:'fi.''ll.\l{l'. •*tiit(' Prlntor, llnrrliibur^, I'a. BOARD OF COMMISSIONERS. Hi.s Excellency, JOHN F. HARTRANPT AkioPaudee, - . . /"'^^■"^"■"^•-"'-to'f William A. Ingham . " " " ' Hk.vry S. Eckkrt, '.. " " ' " ' He.vhy McCoumick, -.."""'' Jamks iMACEAKLANE, - - " ' " ' " JoJix B. Pkakse, - . " ' " ■ - Jo8EPii Wilcox, - . " ' " " " Hon. Daniel J. Morrell, -'"'■■ Henry \V. Oliver, - ' ' ' ' Samuel Q. Brown,' -..,""'' llifBotti-.l, HarrUbur^. HazletoiL Piiihidplphia. Heading. Harrisburo- I owanda. PJiiladelphia. Pliiladeli)liia. Johnstown. Pittsburgh. Pleasantville. SECRETARY OF THE BOARD John B. Pearse, . . . ^^^^IJ. "■■--- Philadelphia. Pj-^ter Lesley, STATE GEOLOGIST. Philadelphia 1878. ASSISTANT GEOLOGISTS. Peksifor Fbazer, Jr.-Goologist in charge of the Survey of York, Adams, Lancaster, and Chester counties. A E. LKHMAN-Toiiographioal Assistant, surveying the Soutn Mountains. Fkei.eiuck Prime, Jr.-Geologist in charge of the Survey of Lehigh, North- ampton, Berks, and Lebanon. A. P. BERLiN-Topographical Assistant, surveying the Limestone Valley and Reading Mountains. John II. DEWEEs-Geologist in charge of the Survey of the Fc^.ail Ore belts of tlie Juniata country. Fbankmn PLATT-Geologistin charge of the Survey of Clcarlield, Jeirerson, Cambria, Somerset, Blair, ^ f-^'to'te of Tlie resolution of iXil i,o,„ , ™ , specifies the object ^"V-ar. >"-'''. ^875, and ••eport on tlie Trap rocks If P '^, ""' «^--"nin.-'Oon and °' a;e Board being ^J^eldTT""''^''' '"« Secreta y Hnnt At the n.ee,i„g'orNoV4 °""™"'"'™te with Dtf Ponod t]>at Dr.Hunthtdaorpted't,/:' ""^ ^''''''■■^^y ■•- Geologist reported that Dr IW h f f * ' '"'" "'« S^te )"s survey in Southern Penning '*'''f '^ commenced necessarily involve a stuiW theT '': '"'' "''" " «'<«'« Tlie volume in hand will s, ffll; f,'"'" ''°*^- necessity. ""' sufficiently attest to this evident The survey of <-}i« a Pe,msyU.„ir, ,Lten:;;?,C,td to tf''"'''™ --1 Eastern gists ot the regular corps, t" w,t ""'"^ '=°"'P'-''«'" «eolo- ^- '»"• aittrritfri viE. LETTER. rivers. This elaborate survey has been in progress under Prof. Prime's able direction since the beginning of the sur- vey. The second volume of his reports of progress is about to issue from tlie press, and his lield-party is engaged in finishing the southern border of the mountain-land, includ- ing the overlapping edge of tlie Trias. To Professor Persifor Frazer Jr. of Philadelphia, was assigned a similar instrumental survey of the Azoic mass of the South Mountain in York, Adams, Franklin and Cum- berhmd counties ; including the Siluro-Cani})rian limestone contact on the northwestern side, and the Trias contact on the southeastern side, with an enclosed limestone valley. Prof. Frazer" s lines however traversed the wide low-lying triangle between the Soutli mountains, the Susquehanna river and the Maryland state-line ; occupied by a broad belt of Trias, by two belts of limestone, and a still broader belt of Azoic slates, of unknown relationship. This impor- tant and minute survey has been going on since 1874, and is far from comph^tion yet. Prof. Frazer in 1877 continued his personal survey of the York county limestones and Azoic slates and gneisses into and over the whole of Lan- caster county, his report of which is nearly ready to go to press. But his field-party continues the slow and laborious work of mapping the South mountains. To Mr. Charles E. Hall has fallen, in a natural way, as the geologist in charge of the State; Museum, the even more difficult task of unraveling the tangled threads of that skein of Azoic gneisses and slates which stretches from the Dela- ware River at Trenton, across the Schuylkill between Phila- delphia and Conshohocken, through Chester and Delaware counties, to the Delaware and Marvland state-lines. Sev- eral thousand hand specimens have been collected and ar- ranged in the museum, for study and comparison ; and every exposure of rock, however insignificant, is not only represented in the cabinet-series of cross-sections, but located on the map. A long stride has already been made towards the true solution of the jiroblem of our Azoic rocks, and of their relationship to the slate, sandstone and lime- stone formations which overlie them. LETTER. E. vii la- la- ire iV- Meanwliile many microscopic and chemical analyses uf these enigmatical rocks have been made by Dr. Genth, tlie Chemist and Mineralogist of the Survey ; who lias also paid great attention to the species of traps collected, and will continue to make a special study of that subject. In sui)port of the assiduous studies by these gentlemen of the Azoic rocks in their respective distri(!ts, and to further the success upon whicli thej^ can already congratu- late themselves, it was unquestionably desirable to compare their observations and conclusions with those made and reached, by geologists outside of the State, in the Azoic regions of New Jersey, Northern New York, New Eng- land, and especially of Canada. No better plan could have been adopted to reach this end than to invite so distin- guished a student of Azoic geology as Dr. Hunt to visit those districts of our survey which seemed to correspond with those in the north among wliich he had spent the best part of his laborious and successful life ; and no book could be more useful tlum one in which he should collate all the known, supjjosed, and susi)ected facts of American Azoic geology ; with all the accepted conclusions, and proposed hypotheses, pul)lished on the subject by the most eminent geologists of the last half century in Europe and America, We owe therefore a debt of gratitude to Dr. Hunt for this historical monograph, which will supply a dee])ly felt deficiency in the literature of our science. It is a treasury of notes and suggestions of the greatest value t(j the geolo- gists of Pennsylvania, and of other States, working in such districts as are occupied at the surface, or are underlaid at moderate depths, by the Cambrian and sub-Cambrian for- mations ; although no linal demonstration has been ncrAmi- jilished by the author of those problems of superposition, unconformability, and identification, at which so many geologists are still half despairingly at work. But his opin- ions of the probable final solutions of these problems will reenforce their own, wdien they agree, and lead to fruitful discussions when they disagree. Dr. Hunt's views on one or two points, like that of the relationships of the slates of the great valley, are i^eculiar i ''?! viii E. LETTER. to himself, and are not in accordance witli the views of the Pennsylvania geologists either of the First or Second sur- veys. But it is of real importance to obtain the circum- stantial statement of his opinions given in this report The linished instrumental survey of these slates and unde. ying mngnesian (Siluro-Cambrian) limestones in Blair county, iind the rapidly advancing surveys of the same outcrops in Clinton, Milllin, Cumberland, Dauphin, and Lebanon coun- ties, with the close instrumental surveys at the Schuylkill, Lehigh, and Delaware water-gaps, confirm our opinion of the correctness of the interpretation made by tlie geologists of the First survey. It is still somewhat premature to dogmatize about the Taconic system ; as it is impossible yet for any competent judge to express a positive opinion respecting the value of such terms as Montalban, Norian, &c., in Pennsylvania; seeing that the closest scrutiny during the last two years has not availed even to make it certain whether the gneiss belt underlmB or ooerlies the mica-slate belt in Bucks, Montgomery, Philadelphia and Chester counties ; although Mr. Hall has made it almost certain now that the Edgehill rock lies at one locality unconformably, and in a synclinal, upon the gneiss, and that the Chester-valley limestone, of later age, occupies this same synclinal. Since Dr. Hunt's observations, made two years ago. Pro- fessor Frazer'has worked out the important section along the Susquehanna river, and determined the great anticlinal uplift across Lancaster county, with gneiss in its axis, throwing off, on opposite dips to the north and south, many thousands of feet of Azoic slates, all of them older than the Cambrian (?) calcareous slates which underlie the mngnesian limestones. And Professor Prime has found graphitic gneiss with limestones in the (Laurentian ?) uplift north of Bethlehem. Light seems fast breaking in upon this dark region of our geology. Respectfully submitted, J. P. LESLEY. E. ix PREFACE BY THE AUTHOR. This volume owes its orioi,, t s oners of tJie Second Geolol.! \"'1'"'"' »' t'-e Commis- fat the author should prl^r. , "7 "'' P«"»^vlv.„ia that State with especiaS n^'i'"!? '!'«^r'°'"^ '" Irap Dykes and tl,e Iron Ores T hi ll '" ^°*'*> ">« of these several points as iriin'.^ "''''qi'ate discussion eration of some of the leasT „ t'''"',"'"^'^^'' "'« «>■'«''- tions in geological scfence """ "'™' ''^''f*'! q»es- «ylvania, was restricted to the un, ' ^'■'°'°°y "^^ ?««"- line scljists, occupving a hot f ' P°'"™ '" "'« "''J'^tal- paleozoic sediment; a,rd t a mo , ^l"'™ ""^ ""cO-staliine «'..ch he gave the name o hX; ""t;' »"r'''"'^ '^™^ *« ever by him declared to be in 1 ' '"'"-''■ '^'^ '">»'- termediate or Azoic series » T? T'^'' '" '"« "'« in- distinguish, lithologicaliv hefJ ",''"'■ " ™P"«»iW.^ to Hypozoie and Azoic S ':! Z t^M 'T '""' """«' '^-.•andWltituey.whichrr^!:;^^--- xE. PUEFACK. included all the rocks below the fossiliferous sedimentary strata, unl has been shown by subsequent investigations to comprise several distinct stratified terranes. A large portion of the rock-masses associated with, and in fact forming an integral part of this Azoic system, were, by the writers last named, included in the category of igneous or erupted rocks. Such were the gneisses, the quartzose or j)etrosilex-porphyries, the greenstones, the serpentines, and the masses of magnetic and spt;'ular oxyds of iron. Othei', and contemporary writers added to this list, labradorite or hypersthene-rock, together with certain crystalline limestones and quartz-rocks. Later restnirches have however led most geologists to the conclusion that by far the greater jjart ol ihese so-called igneous rocks are stratified or indigenous masses, which are not to be con- founded with the distinctly intruuv.^d exotic rocks, such as the true granites, the trachytes, dolerites, etc. ; nor yet with the concretionary veinstones which, like these, traverse the stratified rocks. It was evidently a question of tiie first importance in the proposed investigation to draw the lines between the three orders of crystalline rock-masses Just defined, and to deter- mine whether a so-called trap-dyke is a foreign mass, which has been injected among previously formed neptunean strata, or is itself an oi'iginal part of the si ratified forma- tion. The same question arises with regard to the de])osits of magnetic an(i sj)ecular oxyds of inm, which abound in the crystalline rocks, and, within the last few years, have come to be c(msidered not as intruded but as indigenous masses. The change of views on all these points which has taken place within a generation, constitutes a complete revolution alike in g(M)geny and in geognosy. Otliei', and not less im[)ortant (piestions aiise in this con- nection, with regard to Ihe ohler p:ileo:'.oic formations and their relations to the crystalline terranes. These relations have been tin; subject of much misconcei)tion, and many contradictory hypotheses, and have moreover important bearings on the ])i'oblems })roposed in this report. To pre jiare thesf udeiit foran adecpiate discussion <»f all tliese ques- PUEFACE. E. xi tions, it was felt that notliing less than a historical and critical review of tlie progress of our knowledge of the older rocks of North America would suffice. The publication of Maclure's map and description, in 1817, marks the beginning of sixty years of great activity in the study of American geology, the chief results of which, so far as they bear on the crystalline and other pre- Sihirian formations, it has been the author's ol)ject to set forth in Chapters II- V of the present work. The fact that for more than one half of this time he has been a constant laborer in different parts of the field, may help to justify him in attempting the task, lie has aimed at as great conciseness and brevity as is consistent with clearness of statement, but trusts that the present sketch may serve as the basis of a more complete and extended history of the Pre-Silurian Rocks of North America, which it is his pur- pose to prepare. The succeeding chapters of this report will be devoted to the consideration of the decay of crystalline rocks, and its geological importance, and to the nature and origin of the various deposits oi iron-ores. They will be followed by the author's observations on the geology of southeastern Pennsylvania, and the elucidation of many of the questions raised in the introductory chapter. As the temporary ab- sence of the author from the country will retard for som(» months the completion of the work, it has been thought best to publish separately the first five chapters, which conclude the historical and critical part, so far as regards American stratigraphy. An index will accompany the completed report, and meanwhile the present jjortion is provided with an analysis of the chapters, which, it is hoped, will help to recommend it to students of American geology. T. S. H. BosTON^, Mass., June 1, 187S. I I t t ,S( C O] al to anc grc giu dist Scc( Tho tion of IJ Cic tho I E. xiii CONTEIS^TS. CHAPTER I. Introduction to the GeoijOoy of Southeastern Pennsy'lvania. 01)jcct and plan of this report, page 1. Relations of the so-callod trappoan rocks, 1. Ilypozoic and Azoic systems of H. D. Rogers, 2. Tie distinguisiios three groups in tlie crj'stallino strata, 3. His spb-division of tlie Iowhm- Taloo- zoic into Primal. Auroral, and ^Matinal, 4. Distribution of the llypozoit! rocks; three gnoissic districts, C>. The Blue Ridge in southern Pennsylvania, 7. Errors in the geologiojil map of Pennsylvania, 7. The nortliorn and mid- dle gneissic districts; their Laurentian agic systems, 17. Crystalline strata south of the Susquelianna, called altered Primal, 18. Rogers on the igneous origin of (luartz and crystalline limestones, 10. Strata called altereil Mosozoio sandstone, 19. The various formations siipi)osed by Rogers to have undergone nietamorphism, 20. E;ustorn Pennsylvania on Logan's geological map, 22. CHAPTER IT. Historical Sketch oi- American Pre-Silurian OEOLoay. Mucl lire's geological map of the United States, 1817, p. 23. His Primitive and Transition mcks, 24. Eaton, his fTeological Text-book, 1832, 24, His five great ternar;\- groups of strata, 2."). The Primitive serii-s of Eaton, 2;'). Tlie gneisses of the Macomb-Mountain range, and of tlie Now York Higlilands, distinguished from those of New lOngland, 2(i. The Transition and T.owcr Secondary series, 2(>. The l^pper Secondary series, and the Coal measures, 27. Tlio Transitiiin Argillite, and the I'irstand Second Iain strata, 40. His second M(!taniorpliie, including part of tlie 1 limary, 40. Primary limestones de- clared to bo altered Paleozoic, 41. .Similar views held Ijy Nuttall in 1822, and adopted by II. D. Ilt)gers in 1812, 41. Rogers on tlie supposed alteration of tlie Transition limestones, 42. Mather on the (sruptive origin of some crystiil- lino limestones, 43. Emmons on the Primary rocks of northern New York, 43. ("rysialline limestone, serpentine, liyperstlunie-rock, and iron-ores, re- garded as unstratilied, 43. lOmmoiis icjccts the vicnvs of Nuttall and Mather, and maintains tlie igneous origin of gneiss and otlit^r stratilie(l (irystallino ro<01, above the Medina, iSO. C. 11. Ilitehcook, in ISiJO, refers the Lower Taconie limestones to tiio I'pper Silurian or Devonian, (iO. Adams, in ISli!. conjectun's the Lower Taconi(! series to l)e altered lied saii tiie mciamorphie ("hamplain division, tlie Messrs. Rogers, in 1S44, (»nci ive the Wiiiie Mountains to be tlie suoeeeding Ontario division metamorphosed, (52. Su[)posed organic remains of tlie Clinton lormalion therein, ('>-. C. T. .Ji'ckson, in l.S4t), as.serls tiie Primary ago of the White Mountains, but reganLs tlie (ireen Mountains and the Lower Taconie rocks OS altered Canibrian and Silurian, (V2. lan to he iiue- of Its 39 of 'ren- •49. 'or a and Red bdina CHAPTER Til. History oi" Amkkhan Pre-Sii.uuian Geology, Conpinued. Geology of Canada; observations of Eaton, Enunon.s, and others, (i:{. Geo- logical survey of Canada begun, 1S42, ()4. Early statements of Logan as to the Primary and Transition rocks, ti4. Murray, in l^i;!, calls llic Primary of western Canada. Metamorphic, (Jo. C(mne(!tion of the author with the survey, in 1847, and his subsequent relations tlier(nvith, (id. I'^.xploration of the Ottawa valley by Logan; its gneisses described, in 1S47, as ^^etamorphi(•, (Hi. Their division into a lower anries, 70. Similar views afterwards held by Rivot, and by Dawson, 71. The ancient gneissie grouj) called liaureiitian, in ]S."i4, 72. Th(! name of Iluronian given to both the <'lilo- ritiir greenstones and the copjier-bcariiig trappean series, in 1S,V), 7U. Tin,' 1 lu- ronian then supposed identical with FiOwer Cambrian, 72. TiUter views of Dr. Rigsby, 7;?. Foster and Whitney's reiiort on Lake Superior, 1851,7.'}. Tlu;ir geological cla.ssi(i(ration, 7."5. The greenstones, serpt^ntines, and iron-ores clas.sed with tlic igneous rocks, 7S. Their Azoic system inciludes both tlu; ancient gneissi's anil tlie chloritic greenstone scries, (Laurcntian and Ilnroiiiaii,) 74. Rocks of Keweenaw Point, and of the Rohemian Mountains, 7"). .Fasper and (juart- zijso porphyry of the latter, and of the Porcui)ino Mountains, 7."). Views of Rivot in is.),"), 7(i. He, like Logan, regards the chloritic greenstones and the tnippean rocks as one, and denying the eruptive nature of the latter. imIIs the whole altered I'aleozoie, 77. The ancient gneis.ses supposed by him to bo eruptive granites, 77. Tho conglomerates of the Copper-bearing series, 78. Rivet's extension of the doctrini' of nietaniorphism, 7S. Wliitne.X', in l.S.")7, rejects the ilistiiiction of Laureiiiian and Iluronian as parts of his A/.oie .sys- tem, 79. Ho maintains tlie distin(!tness of tho Copper-bearing series, whic^li he includes in the I'otsdam, 79. Murray's studies of the Iluronian rocks. )8i54-lH()0, 80. In the Geology of Canada, 18(13, the name of Iluronian is re- xvi E. COXTKNTS. stricted to the cliloritic greenstones, then called the Lower Copper-bearing series, 80. TIio trapiioaii rocks, with native cupper, nialvo the Upper Copper- bearing series of Loj^an, Si. Tlio siiijposfd paleozoio age of tiiis series, 82. The overlying simdstono conceived to bo of the age of the Cliazy, 82. Green-Mountain or Xotre-Danio range ; its extension in eastern Can.ada. SS. Erroneous views regarding it given by geological maps, 83. Distinction of crystalline and uncrystalline roclis in the region, 8;{. Tlio (ias[)6 sandstones and lijneslones, 84. Upjx-r Taconii; Argillites and riraywacke, or lludson- Rivcr group, in esistern Canada, S"). They are placed in tlic upper part of the Cliami)lain division, 8."). (-rystalline roclcsof tlie Notre- Danio range, S,"). Thoy are declared U) bo altered Iludson-lliver group, 8(5. .Secti the St. Lawrence, 97. The Ujiper Taconic first named the Quebec formation, 97. Its graptolites de- scribed l)y Hall in 18,55, 98. Logan on the lied sjuidrock of Vermont, 98. Trilobitic fauna of Point Levis discovered, 185(),99. Fauna of the Phillipsburg limestone: studies of Billings, 99. Logan, in I'^i'd, adopting the view of lOm- mons, places tiiese rocks l)elow tlie Trenttju, ItK). Logan's letter to Barrande, 100. Tlie Upper Taconio now called the Quebec group ; its division into Levis, Lauzoii :ind Sillery, 101. These divisions ik'scriljed, 102. Tiic author, on the dolomitfisand limestones of Point Levis, 103. Tiie striiclurcMif Point I^evis do- scribed, 105. The distribution of the organic remains l\wvo found. lOi!. The section on Orleans Island, 10(5. Billings on the Levis fauna, 107. The fauna of the Rod sandrock of Vermont, 108. Fauna from tlie straits of Bellislo, 108. The rocks of Bonne and Pistolet Bays, Newfoundland, 109. Paleontological deductions of Hilliiigs, 110. His suiidivisions of tlie fossilifer- ous strata. 111. Tlie formation holding Paradoxides, 112. Tlie so-called Lower Potsdam formation, 112. Various fauna.s known in tho Upper Taconic or Quo. bee series, 113. Supitoseil relation of the Sill(>rv sandstone; views of Bil- lings and liOgaii, 113. Conclusions of the author iis to the (Quebec section, 114. Probable inversion of tho series, 114. Its rocks compared with tho Tremadoc, Arenig and Menevian of Wales. 115. Logan on the stratigraphy of eastern Canada. Ih!. The fossiliferous strata of Farnham, 117. Probable succession of tho members of tho Quebec group. 117. Views of Hall, in 1802, as to the relations of ihe Hudson-River and Lo- raino forniiitions, 118. Wing and Billings on the fossiliferous rocks of Ver- mont, no. Logan on inversionsof strata in this region, 120. Logan and Hall, in 1863, on the Graywacke and Argillitc of the Hud.son valley, 120. Relations of these older fossiliferous roi^ks totlie Trenton, rticaand Loraine formations, 120. The so-called Hudson anticlinal axis, now supposed by liOgiin to be a CONTENTS. 1^ • • '.. XV 11 great lin(> of fracture and iijilift, 121. Logan's hyiv)tli09is to explain these im- agined stratigrupliioal relations. Evidences, in the Atlantic; lieit, t)rstratigrai>lii('al non-conformity in paleozoic and mesozoic; times, IJI}. Supposed uneoiiformity at the iiaso of the Trenton. 123. Till' ('hazy lormation in the Ottawa basin, and the Muliawi.. valley, 124. Deposition oltlie Trentmi limestone on pre-Caiiilirian rocks, 121. ('i>niinental movement, with submergence, immediately preceding the Trenton period, 12.'>. Its relation to the u|)pcr members of the Champlain division, 12;"). The boundary belwecin these and the ITpper Taeoiiic, not an antii'liiial axis, nor a lino of fracture and uplift, but one of contact between discordant series, 12»i, CHAPTER IV of 09. ^'or- Iver lue. V.il- IH. (oC, kta jup. |liO- ,'er- iall, Ions l)ns, lie a The Ca-mbrian Rocks of Europk and Amkrica. The lower paleozoic rocks of Wales, 128. The Cambrian series, as delintd and divided by Sedgwick, 128. Portions of it wrongly included in the Silu- rian, 129. Sihiro-Canibrian, and Upper and Lower Camljrian, delineil, 129. The latter divisions in Wales, 130. Fauna of the Lower Cambrian, 130. Silu- rian and Cambrian seriesof Sweden, 130. FiK-oidaland l'>>|)hytonsiindsti(nes; their organic forms, 131. Kjorulf on Lower and I'pperTaeonic, and Silurian, in Norway, 131. Cambrian of Russia and Uohemia, 132. Stratigraphical range of Cambrian organic forms, 133. Tlie various graptolitic horizons known in lOumpi', 133. The Potsdam sandstone of the NeM- York series, 134. The Calciferous sand- rock; a dolomit<' with gypsum, 13.'). Organic! remains of the Potsdam; Sco- lithus Canadensis of l>illliigs. i:>.">. S(!olitlms linearis of Hall, its history, 13t>. The transversely grooved Scolithus of the Primal .s;indstone, 13". The aiitlior on the Scolithus of Port Henry, New York, 139. The Chazy formation ; its straligia[ihical relations, i:'.!). The St. Mary"s sjindstone >.f Lake Supcsrior, 140. The liower Magnesian limestoTio of Wisconsin, 141. Its associated glau(!onite, 141. The St. Peter's or Chazy .s;uidstone, 142. The Trenton limestone, tiie Galena or Upiier Magnesian limestone, and the Cincinnati group, of the Mis- sissipjii valley, 142. The Potsdam sjuidstoneof this riigirin ; three stages in its fatnia defined by Hall, 143. The ('ambrian rocks of Missouri, 143. Their litliological dissimilarity to their eciuivalents in the Ea.st, 144. Cambrian rocks of the third or central district of New York, 144. Early observations of Conrad, 144. Vanu.xem on the Puliuski or Loranu; shales, the upper member of the Hudson-River group, 144. Its lower member, the Frankfort .slates, or the Iludson-Kiver slates of Mather. 1 !.">. These two divi sions distinct in Pennsylvania; the latter a partof the Taeoni<; of Emmons, 14.".. The Oneida conglomerate, 14C. Disappearance of the Pulaski shales to the southeast, in the Mohawk valley. 14(). Thinning-out and disappearance of the Trenton limestone iu the same region, 14(5. bE. xviii E. contp:nts. CHAPTER V. nisToiiY OP American Prpj-Sii-urian Geolooy, Concluded. 'I'lu'Tiiiurcntiiin soriesin Canada; its two divisions, as recognized in 184.'), 148. Conuloiiicrato iii(rliil. Tlicir associated gneisses and limestones, l.VJ. Mincfralugical composition of these labradorite- rocks, l.");5. Tlie constitution of plagioiilaso feldspars, 158. 'Die Geology of Canada, publislied in IStJS; tho accompanying Athw, 1")4. Logan on the succi'ssion ni Laurentian rocks on ti>o Ottawa; tho Grenville gntMssic series, and tho Ottawa gneiss, l.jo. Mineralogical constitution of tlieso ortlioclase-gncis.ses, lijo. Thogneissoid anortholite or labradorite-rocks; their UTiconformablo superposition to tlio ries, Kil. Titani3. Ilis chemical and lithological studies of them, and their ini-hided orthoclasc-gneiss. It!!. Interstralilied limc.'stones of tho Laurentian, lO.J. Their eruptive origin maintained by some geologists, Ki."). Concretionary limestone-veins, or en- doginious niiusses, hi,"). Tho Tiaurentiau zinc-ores of Now .Jersey, It;,'), Miner- alogy of the Laurentian lini'-stones, KJG. Masses of gneiss included in <'alca- reous veins; examples at Port Henry, New York, KiO. .Tames Hall on similar ])henoi'iena, 1(!7. Lime.stone-veins in tho Norian, 107. Pro-Cambrian ago of tlu>se calcareous veinstones, 107. Organic remains of tlie Laurentian period; the finding of Eozoon Cana- donse, 108. Its discovery anticipated, 108. Tho observations of McMnllcn in 1858 ; the Eozoonof North IJurgess, 108. Eozoon first described Ijy .J. W. Daw- son in 18<)4, 108. Younger crystalline rocks in H:istings County, Ontario, 109. Observations of Murray, in 1802, and of Maclarlane, in 1S()4, 170. The conglomerates, argil- lites, and limestones and the cldoritic slates and greenstones, 170. Logan (psoil Terrunovan series; it included two terrancs, ISI. Tho White Mountain ^;neissosand mica-schists, cjillod Montallian in 1S71, ISl. The Green-Mountain and White-Mountain rocks helicved to bo altered paleozoic strata, IHii. Tho latter supposed to ho altered lluilson-Iliver yroup, or TJpi>er Taconic, ISJ. TiOj^an on their stratigrapliiy Macfarlane and by Bigsby with the Primitive schisls of Norway, IHC. Tiie similar viowsof II. D. Rogers, as opposed to those of Logan, 187. Tho orystallino rf>cks of Caernarvonshire and Anglcsea; ditlcring views of Hritish geologists, IS7. 'JMitMr lluroiiian age; Dimelian and P(!liidian, ISS. Matthews on lluronian in New Itruns- wiok, 188. Ilis I}loomsl)ury group not altered Devonian, but lluronian, 189. The author, in 1S7(), on tho lluronian of the Atlantic coast, ISO. Its two litho- logic^d divisions: pelrosihix-porphyriesof Massjichusotts, ISO. ( Jhloriiic green- stones and 8eri)entines, 190. Intrusive granites, 191. Micaceous quartzites . His view compared with that of Logan, and both rejected, 197. Tho pro- Cambrian age of these rocks allirmed ; lato results of tho Canada survey, 198. Unpublished letter of W. 15. Rogers on the Blue Ridge in Virginia, 108. Fontaine on tho siuno region; its Laurentian, lluronian, Montalban and Taconic rocks, 100. Tho author on Laurentian, lluronian and Montalban on the Schuylkill, iti Pennsylvania, liUO. On tho I^i' \er Taconic, or Primal and Auroral rocks of that region, liOl. Their crystalline cjharactor, antl included iron-ores, 201. Their partial resemblance to lluronian, 20'J. C. U. Shepard (m the limonites of westtn-n Connecticut, 20li. Epigenio origin of c(M-tain linionites, 203. Magnetites and limonites of tho Primal or Lower Taconic, 204. Crystalline minerals of this series; new species called vcnerite, 205; The author on s;)-called talcose or nacreous schists, 20."). Emmons on the pyrophyllito rocks of tho Lower Taconic, 20o, Organic forms in this series; Scolithus, Lingula, etc., 20(J. The name of Taconian propcsed lor the Lowir Taconic, 207. Geology of the Blue Ridge; Laurentian of Roan Mountain, North Caro- lina, 207. The Montalban series, with granitic veins, and included diniiteor olivine-rcjck, 207. Taconian at theea.stern base of tho Bhio Ridge; it;i(v>lumito, 205. Kerr on tho geology of North Carolina; his Upper Laurentian is Mon- talban, 20S. His lluronian includes the Taconian; charactorsand distrilmtion of tho latter in N. Carolina, 208. Bradley on tho paleo7X)ic age of tlio rocks of the Blue Ris therein, 2l.j. Strati^;rapiiio;il relati. l'"urlii<'r evidenees of a break at the l)aso of the Siluro-Ciunbrian, 21(;. Murray on tlie lluronian in Nuwibundland, 217. The great pro-Cami)rian erosion in that region, 217. lluronian north of the river St. Lawrenee, 217. Brooks on a supposed newer series in northern New York, 218. Geology of Lake Superior ; the lluronian distinguished from the Cojjper- bearing series, 210. TiOgan, iu istio, refers tiio latter t'> the* Quebeo group, 210. Views of various writers on unstratilied and igneous roelis, 220. The author on the indigenous eharucter of the lluronian greenstones, 221. The terms ex- otic and end();icn<)nsa|)plied to roirk-nuussos, 221. Kimball on Laurontian and lluronian of nortiiern Mioiiigan, 221. Credner on the g(M)l()gy of the sjimu region, 222. Its examination liy Brooks and Pumiiellj', 222. UnpuliUshed letter of the author on tin o(;ks of northern Michigan. 22:5. The newer erj-s- tallino or Montall)an roeksof the region, 224. Subsequent studies of tliem by Brooks, 22r>. The lluronian grt'eustones; tlieir lithologieal tiharaeters and associations, 22(i. lluronian greenstones near New Haven, Conn., oalled, by J. D. Dana, tui^tadolerito and metadial)ase, 227. The province of lithology, and its relations to geognosy, 227. Hawes on tlie dioriiic character of tiicse green- stones, 228. Serpentines, and carbonaceous rocks of the lluronian, 22H. The Copper-bearing nxiks of Lake Su[)erior ; their supi)osed stratigrapliical relations to * lie lluronian, 220. The question of t!i<^ petrosilex-poriihyries, 229. Probable lluronian age of the Boliemian mountains, 2110. Stratigraplii- cal break between the lluronian and the Coi>per-bearing series, 230. The latter distinguished, in 1S7:5, as the Kewenaw group, afterward <;alled Keweenian, 2iil, Tills conclusion ado[)tod by Brooks in 1^7"), 21! 1. Irving on the geology of Wisconsin, 231. Laurontian and lluronian of the region, 232. The so-ciiUod altered Potsdam, called lluronian by Hall and by Irving, 232. Its quartzites and petrosilex-porphyries, 232. The Keweenian in Wisconsin, 232. Sweet on its pre-Cambrian age, and on the overlying stuidstones, 233. The Lake Superior or St. Mary's sandstone referred to the Potsdam Ijy llominger, 233. Overlying Calcil'orous and Chazy formations, 234. Bradley's geologictd map, 1S7<') ; ho calls the lluronian altered Silurian, 234. Views of Sir W. E. Logan, and of Solwyn, 235. Irving (m the pre-Cambrian ago of both lluronian and Keweenian, 235. No motamorphism of paleoaiic strata in the west, 23(5. Relations of Taconian to Keweenian, 23(5. The arguments for the meso2a)io ago of tho latter, 237. Chronological value of the niineralogicjd characters of exotic rocks considered, 237. Supjioscil organic markings in Keweenian rocks, 237. The two groups of sedimentary i-ocks on Thunder Bay, Lake Superior, 238. The lower or carbonaceous group, with sil- ver-bearing veins, 238. The upper or variegated dolomitic group, 230. These probably distinct from and younger than the Keweenian, antl called Animikio and Nipigon groups, 240. Views of Logan, Mucfarlane, Bell, and the author as to these rocks, 241. List of pro-Silurian terranea in North America, 241. Local variations in Cambrian sediments, and their cause, 242. Rclationsof pre-Cambrian terranea to one another, 242. Laurontian of the Rocky Mountains and the Wahsjitch range, 243. lluronian of the Sierras, and uriferous rocks of California, 244. Laurontian and lluronian in tho Alps; the pietri vcrdi, 244. Succeeding limestone group in that region, 246. \ COxVTENTS. E. XX i Note ..„ tho Mnntanmnvoinst.Mios '4,1 r „ . . the younKer K,„.Usio „r Montall.an 'sJr 1 . r I "'^nervations of Bnx.ks on slun. ; us estimated tl.i,.k„.as, -'is Tin r, i... '^'"""'^''^"' *'» ^'«w llan.p- nradloy on the 151..,. liUhn in r • ""'' ^'•""""o.s, L'48. ' ^>tsUan..Q..e.,e.,a„.CM;;;!c;,: ;;;;:;;; ^^i ^;.;;;so-.a,U...aU. Georgia,-.'.^,). Tl.o rooks of Atlanf, -\:- "'■"^"'"^ "l«frvati„„s i„ Gap, 2.50. Mont.dl,an a..> ^ ' i:; ?'"'""'"•"'" '^^"""t Airv to r„ak. Stone Mountain. ,.,, I>;. './^.^^^r;, ^"- ''--....aMo Ta,.o„ia„ ,..,t. Si and n.ica-sohists. -,,. Tl.e (' Ih it "'«.;•''«"•" = N..- hornM.,,,,,-,^,,, .j,,,,^ 251. Their supposed a.tl^^aJir^r ';■;' :;;;r^'T'''"™" ^^^'"^ '" '^-^«!'' ron. s,.ooession. and its (aliacies. ^^2 ^ i ^ 1^ ''^^ '"• ''^"^' '"•-" "^ the MontalLan, 2,-.i'. Tl.e arLMn„.nr .l^Z '""''''^ ^.ows ,us to the ago of genesis of orystalline rooks "v" ««PIK.sed tnmsitions, 253. The ( V d a n li ol a t'u th. OIK cru CIIArTEU I. IXTRODUCirOX. S 1. In till) month of Ano-ii.t isr.: T ConimiasioMcra for tlio - '" "'« «-.t« evi,lo„t that tho ork- 1 , "J ^''''""■' ■^''"- ^° """ i* Of .ho,-r goognostic': r:,rtt,r":,t° ^t ^v- ""'"^ " T'^- a -. wi„o .n,o Of i.,.,,, h.oif;";,:: ;.;;::c;t::;: tl.oy oxotio lET "™"' ""^'S""""^' ""d I'ow far aro onfartrerho?:ft:;T:i;:o'r°'^^'r°"'"'"'--'>" Inasmuch as thoro nro n Mo' ?"■ '^"'='»«i°S ^fata ? «™p-o.c.,.h.;=::fi--t^-;.o.a [1 E.J 2 E. SPECIAL KEI'OUT. T. STEKRY HUNT, 18 V5. itiaHmucli, moreover, as other rocks, by many regarded as erup- tive, are found enclosed in the older formations, (the mineral characters of which tliey are generally .supposed to ha. c modi- fied,) it became evident that a proper discussion of the trappian rocks would require a review of the geology of the whole re- gion. Add to this the history of the iron ores, some of which are commonly believed to have intimate relations witli the trajis ; and, moreover, the history of the so-called azoic i-oeks, and the field presented for my geological investigations be- comes a very wide one. By Azoic rocks are generally understood the whole of the Prnnary crystalline rocks of prepaleozoie age, for which the names of Archaean and Eozoic liave also been suggested. Rog- ers, it is true, restricted the name of Azoic to a portion of these Primary rocks, while he designated another }iortion of them as llypozoic. I have, however, interpreted the term, as used above by Prof. Lesley, in its usual sense, and .shall include under this title the whole of the Primary or Eozoic formations known in Pemis^'lvania. § 2. The region to which my inquiries were directed is that part of the State lying to the south and east of the North or Kittatinny Mountain, and includes, besides the Mesozoic sand- stones and the rocks designated by Prof. Henry D. liogers as the Primal, Auroi-al and Matinal divisions of the Paleozoic Bystem, a great development of crystalline stratitied rocks. These were by him divided into an older Uneissic or llyijozoic series, and an upper Semi-metamorphic or Azoic series, the re- lations of which to one another and to the I'aleozoic system are very intimate, and gave rise to certain ambiguities in the descriptions and the nomenclature as set forth by liim in his filial report on the geology of I'ennsylvania, published in lWo8. § ;}. As regards the distinctions between the liypozi/ic and Azoic series, those were declareil to be : "■ First, an obvious and very general dillerence in the composition of the two sets of strata: secondly, a marked dillerence in their conditions of metamoiphism : and thirdly, and more esjiecially, u striking contrast in the direction and manner of their u}ilift ; the [ili- cations and utidulations of the less metaniorphic series dipping almost invariably south-eastward, while the gneiss, in many IIYPOZOIC AND AZOIC ROCKS OF ROGERS. E :i localities, has no symmetrical foldings, but only u broad out crop, dipping to a different quarter. These structural dissimi- larities imjily essential differences in the direction and date of the crust-movetuents which lifted and transforn.ed the respec tive grou])s, and led the geologists of I'ennsylvania and Vir- ginia to a conviction that, over at least many tracts, there would yet be discovered a physical unconformity lioth in strike and dip. It was not, however, until a relatively late date in the prosecution of the Geological Survey of Pennsylvania that the geologist of that State detected positive evidence of this [»hysi- cal break, ami of a lapse of time between the two groups of Btrata." § 4. " We have then in the Atlantic slope, by actual demon- stration, but one physical break or horizon of unconformity throughout the immense succession of altered crystalline sedi- mentary strata and, within this region, but one paleontological horizon — that, namely, of the already discovered dawn of life among the American strata. This latter plane or limit, mark- ing the transition irom the nou-fossiliferous or Azoic deposits to those containing organic remains, lies within the middle of the Primal series or group of the I'ennsylvania survey ; that is to say, in the Primal white sandstone, which, even where very vitreous, and abounding in crystalline mineral aggregations, contains its distinctive fossil, the SeolUhus linearis. The I'rimal slates, beneath the sandstone and in intimate alternation with it, possess not a vestige of organic life, nor has any such yet been discovered anywhere within the limits of the Atlantic slo])C, or on the northern or western borders of the great Ap- palachian basin of ^orth Ainerica, either in the Lower Primal slate or in the other Semi-metumorphic grits and schists physi- cally conformable with it, into which the true Paleozoic se- quence of our formations, physically, extends downwards." §5. We have', then in the language of Rogers. " two main horizons, sub-dividing the more or less nictamorphic strata of the Atlantic slope in three systems or groups ; the one, a physi- cal break or interruption in the original dejiosition of the masses ; the other, a life-limit or plane, denoting the first advent, so far as yet discovered, of oiganic l)eings. As tliese two planes are not eoincitlent, Init include between them a thick group of M m 4 E. SrEClAL UEl'OKT OF T. STEIUIY ULNT, 1875. Bedimeiitary rocks separated from the lower, physically, and from the ujtper, ontologically," the author was led " to employ a classitication which recoo;nizc3 a three-fold division of all these lower strata." These three groups he defined to be the ILjpozok rocks, or those beneath any life-bearing strata; the Azoic^ or those destitute of any discovered relics of life ; and the Paleozoic, containing the remains of ancient life. (Sec the Ge- ology of Pennsylvania, 1858, vol. I, pages 62-64.) § 6. In addition to the relation of continuity already asserted between the Azoic and Talcozoic groujis, we arc liirther told, in the chapter just quoted, that the "Azoic or talco-niicaceous group is a genuine downward extension of the I'rinuil i'aleo- zoic scries;" while in a succeeding chapter, tiie whole of the Azoic series is expressly included in the I'aleozoic system, of which it constitutes the lower portions, in the preceding ex- tracts, the Azoic rocks are sx)oken of as comprising the Lower I'rimal slate, and a group of tSemi-metaniorpliic grits and schists physically conformable with il; but, farther on in the pages of Kogers, the latter alone are distinguished by the name of Azoic, under the head of the Paleozoic system. § 7. The Ajjpalachian Paleozoic strata of Pennsylvania, as defined by our author, arc said to be, in asccndiug order, as follows: " Primal Crystalline Schists (or Azoic Group.) — A very thick and widely difiused group of semi-crystalline strata, in- durated clay -slates, talcose, micaceous and hornblendic schists and gray silicious grits, without visible fossils, but in closo physical relations with tlie overlying fossiliferous l*rimal rocks, and apparently a portion of the Paleozoic system." To this division succeeds four mjmbcrs, described as portions of the Primal Series, namely : " Prlmal Conqlomkrate. — A heterogeneous conglomerate composed of quartzose, feldspatl.'ic and other pebbles, included in a silicious or talco-silicious cement. This rock does not ap- pear in Pennsylvania, but is largely developed in Virginia and in Tennessee, where it has a thickness of 150 feet. This for- mation, jind the preceding, seem to lie below the lowest ascer- tained fossiliferous horizon." PALEOZ'UC KOCKS OF HOGEllS. i:. 5 "Primal Older Slate. — A sandy slate of al)rown or green- ish gray color, containing much lelJspatliic and talcose matter. It has hitherto disclosed no fossils. The thickness of this rock has not been ascertained in Pennsylvania, the beds being too much folded. In Virginia it is 1,200 feet thick." " 1'rlmal White Sandstone. — A compact, fine-grained white and yellowish vitreous sandstone, containing specks of kaolin. The stratum is distinguished by a cylindrical stem-like fossil, the Scolilhus lincuris, which crosses the beds in a perpendicular direction. l*robable thickness about 300 feet." " Prlmal UrrER Slate. — A greenish blue and brownish talco- argillaceous slate, very soft and slialy ; its only fossil a peculiar fucoid. It is probably about 700 feet in Pennsylvania." § h. To these succeed the Auroral Series, consisting of two members, which are, in ascending order: ''Auroral Calcareous Sandstone. — A coarse gray calca- reous sandstone, containing drusy cavities enclosing crystals of quartz and calcareous sjia.. Within the limits of Pennsylvania this occurs chietly in Northampton, Centre and Huntingdon counties. It is about sixty feet at l^aston." "Auroral Maqnesian Limestone. — A light blue and bluish- gray massive limestone, containing generally from ten to thirty- five per cent of carbonate of magnesia. In the southwestern part of Pennsylvania it contains thick beds of chert. Its thick- ness is from 2,500 to 5,500 feet." § 9. Of these divisions the Primal white sandstone was by llt)gers regarded as the equivalent of the Potsdam of the New York series ; and the lower and upper members of the Auroral, respectively, as the representatives of the Caleifbrous sandiock, and the united Chazy and Black Kiver limestones of New York. The Auroral is followed in ascending order by the Matinal Scries, in three divisions, namely: the ilatinal argillaceous limestone, tlio Matinal black slate, and the Matinal shale; supposed to be equivalents respectively of the Trenton lime- stone, the Utica slate, and the so-called Hudson Kiver shales of New York. (Ibid, I, page 104.) § 10. Crystalline characters were not, however, according to Rogers, supposed to be contined to the liypozoic and the Azoic ?j 6 E. SPECIAL IJEPORT. T. STEllKY HUNT, 187J. H ' hV"! or Lower Priraal strata. The Primal white sandstone and the Upper Primal slates, as well as the Auroral and Matinal series, in various localities, are described as being more or less crystal- line in form, from so-called metamoridiic action ; which is even supjiosed by Rogers to have changed the Mesozoic, in some places, into a crystalline rock. Tiie whole of the Primal strata below the white sandstone are elsewhere described as alterna- tions of talcoid silicious slate, talco-micaceous slate and quartz- ose micaceous rock, usually schistose, besides other strata wiiieh are nearly pure clay-slate. Greenish talcose slates arc, more- over, said to be associated both with the white massive lime- stone and the blue limestone of the Auroral series. § 11. The larger part of the crystalline rocks of the State are by Rogers referred to theGneissicor llypozoic series, although we are told that near the Susquehanna it is difficult to distin- guish the silicious talco-mieaceous I'rimal from the more mica- ceous beds of the llNpozoic. Elsewhere it is declared that whore these Lower Primal or Azoic strata " display their maxi- mum amount of crystalline structure or metamorphism, the members of the twogroujis often simulate each other so closely, and indeed are so identical in mineral aspect and structure, as to bailie all attemptsat distinguishing them lithologically ; nev- ertheless it will appear IVom the evidence embodied in the sec- tions illustrating this country that they are distinct systems, occuiiying separate zones, susceptible of delineation in the geo- logical map." (Ibid. I, page 60.) § 12. He defined three areas or districts of the Gneissic or llypozoic series in tlie State of J'cnnsylvania. The Northern district, being the South Mountain belt, is a prolongation of the Highlands of the Hudson and of New Jersey, whicli crossing the Delaware below Easton, extends to Reading on the Schuyl- kill, stretching along the north side of the Mesozoic sandstone belt. The Middle gneissic district extends from near Valley Forge on the Schuylkill, westward into J^ancastcr county, and includes the Welsh Mountain, between the Mesozoic on the north and the limestone valley of Chef ter county on the south. The third or Southern district is that extending from the Dela- ware at Trenton to the Susquehanna south of the State line, and lies whoUv south of the limestone vallev of Chester and CJNEISSIC DISTRICTS OF ROGIiUS. E. 7 Montgomery counties, except when the gneiss passes around the east end of the limestone, and lies between it and the southern border of the Mesozoic for a little distance near the eastern corner of the last named county. This SouiIktu gneissic dis- trict, in the words of liogcrs, '"lireaks otf to the west of the Brandywine river in a succession of narrow tongues. Near the State line of Delaware it sends forth, however, through the south-east corner of Chester county, a continuous and widening belt to the Susquehanna." To the "west of the Brandywine the gneissic rocks sink under the altered I'rimal strata in a succession of anticlinal lingers on slender j)romontorics." The line of demarkation between these two "series is nut, however, a simple une, but is intricately loo})ed in consequence of numer- ous nearly parallel anticlinal foldings of the strata, sending promontories or tingers of the older rocks within the area of the newer or Semi-metamorphic to the west of their average boundary." ([bid I, i)ages Go, GO, G7.) To the west of this irregular boundary, the whole of the crystalline rocks, which, i)n both sides of the Susquehanna, ex- tend to the south of the limestone valley of Lancaster cuunty as far as the Maryland line — where through the narrowing of this valley they are brought to the Mesozoic — are rei)resented by Rogers, both in the rej)ort and in the geological map, as " Primal altered," with some areas o\' "Auroral altered." § 18. Still farther west, and beyond the Mesozoic, is a large and important mountain area, the northern extension of the Blue Ridge, stretching nearly to the Susquehanna, which is also described by Rogers as ''Primal altered" (Ibid. 1, {)age 204.) This, liowever, in the geological maj), is designated as unaltered "Primal." The same is true ot some stuall areas of crystalline slates which ap[)ear iji the midst of the Auroral limestt)ne near theSus([uehanna, to the south-east of the Mesozoic. In calling attention to this discrepancy bi'tween the maii and tin text, I wish to jtoint to another of eonsideral)le inqiortance. It will bo found, (at least in the copy of the geoU)gical map of L*emi- sylvania before me,) that the Gneissic series in the tlie legend is represented by a diagonally-lined pjjik color, which however, on the map, is confined tc the Southern district ; the Middle and Northern gnei.ssie districts being of a piidc color, but unlinod. M 8 E. SPECIAL KEPOKT. T. STERRY HUNT, 1875. Inasmuch as Rogers refers the whole throe to the same series, tliere is evidentlj' an' error on the part of tiie cartograplier. It seems prohuble the unlined pink of the districts hist mentioned was intended to represent the gneiss. The student of the map will also bear in mind that the areas designated as "Primal,' near York, and west of the Mesozoic, and colored a pale yellow, Avithout lines, should, in conformity with the text of liogers, receive that color which, according to the le- gend, belongs to the "Primal altered." It may also be ob- served that the diagonally-lined pale yellow, said in the legend to represent Primal roofing-slates, does not appear upon the geological map. § 1-1. The characters of the three gnesssic district are de- scribed with some detail by Rogers, who shows that the rocks of the Northern and Middle districts are very unlike those of the Southern. They consist, according to him, of coarse gneisses, resembling granite, but distinctly stratified, often made up chiefly of quartz and feldspar, frequently hornblendic, and abounding in magnetic iron ore, but rarely containing mica. lie also notes the rarity of micaceous, talcose or chlo- ritic rocks, which abound in the Southern district. The Middle district presents some small exposures of highly crystalline limestone with graphite ; and the Northern one, near Easton, also exhibits beds of serpentine, with some crystalline car- bonate of lime, accompanied with tremolite, light colored jiy- roxene, brown tourmaline, graphite, and, as I have observed, with large crystals of magnesian mica. The mineralogical and lithological characters of these rocks are similar to those met with in the Highland range in New York and New Jer- yey, of which this is a continuation; and it was after a careful consideration of all these circumstances that the geological survey of Canada, in the map of eastern North America, pub- lished in 18GG, represented both the Northern and the Middle gneics'c districts of Pennsylvania as belonging to the Laureu- tian series ; to which the gneisses of the Highland range and the Adirondacks had already been referred. § 15. The geological structure of these two gneissic regions in Pennsylvania was described by Rogers as presenting a series of closely appresscd folds, most clearly seen in the South Mountain, SOUTHERN GNEISS DISTOICT. E. 9 of which he says, "It will be seen that from one end of tho ran^e to the other the gneiss, and the older Appalachian strata in contact with it, are bent into a series of folded or inverted llcxuies; that is to say, having the strata in the north leg of each anticlinal turned over, and dipping steeply to the south, or ^rather to the south-east, in accordance with the law so univcr- salthroughout our whole Appalachian chain. Near the Dela- ware, as shown both in the general and the local sections, there are three distinct ridges of the gneiss, separated by two syncli- nal troughs of the Auroml limestone. IJere the entire breadth of the chain is almost seven and a half miles. At the eastern corner of iJcrks county the breadth is about six miles. Here they (the ridges) consist almost exclusively of the gneissic rocks. Near the Schuylkill, the whole belt is much contracted, consisting chietly of the spurs of the Neversink mountains, and the ridges are composed almost exclusively of the Trimal white sandstone in an altered and much indurated state." (Geol. I'enn. II, page 94.) The above structure is shown in numerous sections given by Rogers. § IG. In further illustration of the inversion of the strata our author remarks that along the southern side of the great limestone valley, near the Lehigh, tho dip of the limestone is, in very many places, to the southward, or towards the gneissic belt, sometimes at an angle of 00°. He adds: ''The existence of a steep southern dip along the south side of this valley is in strict analogy with tlie position of the rocks generally in tho valleys of the whole South Mountain chain, and implies an overtiming of the strata to the north. This folding of the beds upon themselves in the synclinal axis of our first great moun- tain, though highly curious, is a i)revailing feature from Ver- mont to Tennessee." (5th Annual Keport, page 25.) § 17. We have next to consider the gneissic rocks of the Southern district, the difi'erence between which and the North- ern one (setting aside for the jiresent that of the iliddle dis- trict, declared to be similar to the Northern) is referred to by Kogers as "an essential want of corresiK)ndence between the two regions, in tho gneiss itself," and as a "marked dilierence in the composition of the predominant rock of the two gneissic ranges, which must be ascribed to an original ditftirence in the m 10 E. SPECIAL KEl'OKT. T. STERUY HUNT, 1875. hi chemical nature of the strata.'' This Southern district more- over presents in its ditierent parts such dissimilarities that Rogers was led to divide it into three longitudinal belts, dis- tinguished by mineralogical and lithological characters. The importance which I ascribe to these three divisions is such that I condense from the pages of Prof. Rogers the following de- scriptions (Geol. Penn. I, pages 64-10-4.). § 18. The southern division or group ot the Southern gneissic district is that which is seen on the Schuylkill from Gray's Ferry to tlie upper end of Manayunk, and includes the region of Philadelphia and Gcrmantown. Of its gneissic rocks, the most common or typical variety of all is a gray, bluish, r..;her finely laminated mixture of quartz, feldspar and mica ; the quartz, for the most part, white or trans])arent, the feldspar usually white, and the mica generalh- black or dark brown, and in small plates. This rock occasionally includes small garnets. Next in frequency to this is a dark bluish-gray, sometimes greenish-black gneiss, composed of hornblende au(i quartz, sometimes with a little feldspar; the hornblende always greatly predominating. This rock is usually very iine-grained and thinly bedded. A third common variety in this group is a micaceous quartz rock, generally of a light gray color. Some beds, from a pre- dominance of finely granular ([uartz, and a subordinate amount of disseminated mica, have the characters of a whetstone. A much coarser kind of gray micaceous gneiss, consisting of a predominance of rather large Hakes of mica, with a subordinate quantity of feldspar and quartz, occurs interstratitied with all these other species, as a very usual transition-variety between the ordinary gray gneiss and the highly micaceous kinds, which apitroach mica-slate. It is very usual to find the typical gneiss alternating with the hornblendic species, and both of these al- ternating with the quartzo-micaceous variety. Interst ratified among these varieties f)f gneiss are beds more or less thick, so abounding in mica as to be entitled to the name of mica-slate. Occasional beds of the typical feldspathic gneiss are made }KM-phyritic by the presence of more or less insulated segrega- tions of crystalline feldspar, the longer axes of which generally lie jtarallel to the lamination of the rock. Garnet in small SOUTIIEKN (iNKISS DISTRICT. K 11 isolated crystals is common in tiiL-su rocks, especially in tliu more micaceous varieties, besides staurolite, cyanite and rutiJe. § 19. The stratified rocks of this Philadelphia group, accord- ing to Kogers, enclose various "unstratitied or true igneous rocks" including "a peculiar feldspathic sijetiite (a somewhat hornblendic granite) in thick dykes, also a white coarse- grained granite, consisting of feldspar and (juartz in tortuous and sometimes ramilying \o'\n'6, yrcen stone and other forms of trap-rock in dykes, and also quartz, chroniiferous iron ore and other minerals, occurring singly or associated in the shape of elongated thin dykes or narrow veins. To these should per- hai)S be added some of the masses of ser}ientine, for the unstrati- tied character of these last named is no longer doubtful." § 20. The middle division or groujt of this Southern gneissie district, where it a[)pears on the t;cliuylkill, is described by our author as very similar to the southern one, and as consisting of an alternation of four principal varieties of rock. The most abundant is a very micaceous and garnetiferous gneiss, includ- ing feldspar and quartz, and having a waved, twisted or undu- lating lamination, due to the fact that tlie crystalline plates ot mica, displaced by the grains of quartz, are often arranged ob- liquely to the bedding of the rock. The next most common variety is described as consisting almost entirely of this wavy mica. The rock however graduates into the more micaceous sorts of gneiss by a greater or less admixture of finely granular crystalline quartz, feldspar and hornbk'nde. Thesoutliern halt" of this middle group consists of an alternation of these two varie- ties of micaceous gneiss, with beds of athinlv laminated horn- blendic gneiss; which may sometimes rather bo called a horn- blende-slate. § 21. The northern half ol' the group consists largely of a fourth variety, described as a gray, fine-grained mixture ot granular quartz and minutely crystalline scales of mica, the for- mer predominating and constituting a kind of wlu'tstone. This rock breaks readily into long narrow masses, with smooth sides and ragged extremiti(!S, like half-decayed tibrous wood. On its southern side, this rock, which occupies a considerable breadtii, is said to alternate with the coarse mica-slates, and on ilJ ;;(■ 12 E. SPECIAL REPORT. T. STEURY HUNT, 1875. the north with greenish talcoso slates, which, with serpentines and steatite, mark the summit of the middle group of these gneiwsic rocks, as defined hy Rogers. This steatitie range is descrihed as extendiiij; from near Chestnut Hill to about a mile west of Morion Square, gradually widening from a narrow belt on the Wissahickon to one-eighth of a mile on the iSchuyl- kill, and to nearly four times that breadth two miles farther westward ; beyond which it is said to divi;e of gneiss, regarded by Rogers as identical with that whicii, upon the Seliuylkill, forms the northern ilivision of the Stmthern gneissic district. At the falls of the Delaware, at Trenton, according to him, the rock is a dark hornblendic gneiss, di[»ping steeply south-south-east. § 29. We have seen that our author (§ 2G) looks upon the whole of this Southcri gneissic region as made up of two groups of strata, a lower and more feldsjiathie series, apjicaring on the two sides of the basin, and a newer and more micaceous series, oc- cupying the centre of the synclinal. It might be supposed that these two divisions correspond respectively to the Ily- pozoic and Azoic series of tlie autiior, but the whole suc- cession is described under the iiead of the older crystalline Gneissic strata, or the llypozoic series ; which is elsewhere said to ''consist of true gneiss in all its varieties, quartzose, felds- pathic, micaceous and hornblendic, with fully developed or typi- cal mica-schist, talc-schist, chlorite-schist and the other crystal- line schists usually classed with the genuine or older (llypozoic) gneiss." (Vol. II, p. 7-14.) § 30. With regard to the belt of magnesian rocks in the gneis- sic region of the Schuylkill, he says : '"Viewing the steatite as a stratified rock of the mica-slate group, we may reasonably re- gard it as having L>een metamorphosed to its i>resent condition and structure by infusion of magnesian matter from the dyke of serpentine, which everywhere adjoins it." (Vol. I, p. 72.) Elsewhere he describes a similar belt of rocks, a little farther to the west, as comprising both "true injected ser[)entine and serpentinous steatitic talc-schist." The reader is, however, soon after perjtlexed to find that the serpentines and steatites of the Schuylkill, and indeed of all the region south of the limestone valley of Montgomery and Chester counties, are described in detail at the end of the chapter on the Primal rocks (Vol. I, \,\i. 107-172,); leaving it to be in- ferred, though nowhere distinctly stated, that these are, in some way, related to the Lower Primal (which we iiave seen to be tr. 16 E. SPECIAL REPORT. T. STERRY HUNT, 1875. synoDj-moijs in the nomencliiturc of Rogers with tlic Azoic,) ratlier tluiu to the Il^'pozoic series. § 31, It iiuiy, however, he noted that of the serpentine areas represented on his geological map, one, that of the Schuylkill, is placed wholly within the Hypozoic, and another, that of Texiis nciir the Susquehanna, in the Azoic or I'rinial. Those of South Valley Hill, of the I'aoli, as well as the serpentine belt along the Marvland state-line, are each described as bounded to the southward by massive gneissic rocks, which, io the case of the last named, appear to be unconformable in dip with the serpentine. To the northward, the last two belts are said, to be bounded by talcose or micaceous and argillaceous slates, including the roofing-slates of Peach Bottom, regarded as Lower Primal. In the case of the serpentine and stcatitic belt of South Valley Hill, the gneiss is again repeated, scp.arating it from a limestone valley to the north. The Unionville ser- pentine region is described as being wholly in the midst of micaceous and talcose schists. (Vol.1, pp. 1G7-172.) § 32. In cxi)lanation of this it must be remembered that all the true serjtentines were looked upon by Rogers as intruded igneous masses, the eruption of which was accompai:icd by an infusion of magncsiiui matter, which had changed into talcose and serpentinous rocks, the micaceous schists, both of the Azoic and Hypozoic series. The more micaceous portions of the Hypozoic are, moreover, declared to rcsenibio so closely the micaceous schists of ;ho Azoic "in mineral aspect and structure as to balllo all o'lcmpts at distinguishing them litho- logically." § 33. This point is further discussed near the close of our author's second volume, where, in a sketch of the geolog}- of tho United States, after referring to the labors ot the Canada (jico- logical Survey, which had, in 1847-1852, pointed out the exist- ence of a series of crystalline schists intermediate between tho ancient gneissic system and the Paleozoic series, ho refei's to the investigations of I'rof William B. Rogers in Virginia, who had,as(>arly as 1830, recognized a similar series east of the Blue Kidge in Virginia. These rocks, extending along the "Atlantic slope of the southern stales," were saiossibility of ascertaining at present the true base of tbe Paleozoic system ; for the history of geology forbids us to believe that research has yet detected the actual horizon of the dawn of animal and vegetable life upon our globe." (Vol. II, page 745.) § 35. The crystalline condition which characterizes the in- termediate or so-called Azoic series, in some cases, according to Rogers, extends upward, embracing all the members of the Paleozoic series mentioned in §§7-l\ We arc told tliat the Primal white sandstone is occasionally converted into a vitreous quartzite, and at other times into a " stratified i'eldspar rock," while "the limestones at the passage of the Primal into the Auroral," or as elsewhere defined, at "the alternations of Primal slate and Auroral limestone, are converted into crystalline dolo- mite or marble, with seams and partings of crystalline scaly talc." The Auroral limestone is said to become "a white and 2— K. m 18 E SPECIAL REPORT. T. STERRY HUXT, 1875. mottled marble, with semi-plumbagitious laminae" ; while the gray sandstone of the Matinal series becomes "a highly in- durated Bcmi-porphyritic grit," and the Matiiuil shale'' a serai- crystalline clay-hlate, partially talcose or micaceous." § 'in. In illustration of these statements we may cite the ac- count given by liogers of an area of crystalline rocks met with in the South Mountain, to the south of the Susquehanna river. The strata are described as chietiy of three classes ; one being a group of chloritic, micaceous and talcose slates, with hard green rocks abounding in epidote and quartz, sometimes with a&bestus, and containing occasionally small portions of copper ores and of native co[)per. A second class includes several va- rieties of what is described as a reddish jaspery rock ; elsewhere called a highlv altered jaspery slate, red or reddish-gray in color, and sometimes holding s^iecks of red I'oldspar and small veins of epidote. In addition to these is a third class, of gran- ular quartzites or sandstones, sometimes described as talcose and (juartzose conglomerates. § 37. These rocks, which rise in a series of parallel ridges on the south-eastern border of the great valley of Auroral lime- stone, were l)y Rogers regarded as juembers of tlie Primal aeries ; the reddish jasper}' strata being the Primal upper slates, "greatly modided in texture by the intrusion of quartz, and by other igneous action ;" intrusive greenstones and traps being mentioned as occurring m the series. Elsewhere we have seen that the Primal white sandstone itself was supposed to become, by alteration, a feldspar-rock. To the Primal lower slatej are referred at least a portion ot the greenish chloritic and ejtidotic rocks of the region; while the sandstones with talcose slates are supposed to represent the Primal white saiul- stone. § 38. These strata present, with some exceptions, dips to the south-east, often at high angles, and the structure of the re- gion is described by Kogers as a series of folds, with inverted dips. In illustration of this we are told that on the north- west side of the mountain the Primal upper slates are found dijtjting southward, and overlaid by the Primal sandstone ; while from beneath this, on the crests of the anticlinals, a|)pear the greenish ejtidotic strata of the i'rimal h)wer slates. Portions I ALTERED MESOZOIC OF ROGERS. E. 19 of the Auroral limestone are found, in one or more places, in the synclinal folds of this mountain-helt ; and in one locality arc associated with the hydrous iron ore wliich usually accompanies this limestone series. (Vol. I., pp. 202-207.) § 39. It will be observed that under the head of eruptive or igneous rocks Rogers includes the so-culled dykes of serpen- tine ; and, moreover, that the greenstones and epid(»tic rocks, which are abundant in many parts of the schistose crystalline strata, are spoken of as eruittive or plutonic in character; while even the quartz veins found cutting the strata were regarded as of igneous origin. It is moreover suggested that the Primal sandstone itself may have been derived ''from the great dykes and veins of auriferous quartz," supposed to have issued "in a melted conditioTi through rents and fissures in the earth's crust; outgushing bodies of this quartz," chilled by contact with cold water, having been broken up into sand, and subse- quently spread over the ocean's bottom. (Vol. II, page 780.) Elsewhere he speaks of a belt of sparry limestone associated with the gneiss of the Welsh Mountain, and traced for a mile and a half, as follows: "Whether this limestone is a true ig- neous dyke or vein of carbonate of lime, or a closely compressed trough of sedimentary limestone, metamorphosed by heat, I will not undertake to f^i^.y.^' (Vol. I, page 90.) These extracts aiv made not in a spirit of invidious criticism, but because we shall have, farther on, to point out certain erroi-s with regard to these crystalline strata, which had their origin in the ex- aggerated plutonic views of the author. Tiiese, however, he shared with many others of his time. § 40. This notice of our author's account of the crystalline roclvs of this region would not be c()ni[)lete without reference to the su^iposed altered Mesozoic sandstone, found associated with several deposits of iron ores, in contact with the gneiss of the Middle district, and at a greater or less distance south of the border of the great belt of Mesozoi<^ rocks. They are, ac- cording to him, connected with faults or dislocations; "which are so many rupture;densburgh." lie remarked a great re- semblance between the rocks of the Macomb Mountains and the Highlands of tlie Hudson ; adding, "they are remarkably char- acterized, and distinguished from the Primitive rocks of Xew England, and most European districts, by their great propor- tion of hornblende-rocks, and by the presence of tabular-spar, grains of inters[»ersed serpentine, coccolite, colophonite and masses of diallage." (Text-book, pages 68 and 6.) "The gneips (of the Macomb Mountains) is more nearly in a hori- zontal position than is usual for rocks of gneiss in New Eng- land." (Geol. Survey, i>age 42.) § 52. We come next to his second or Transition series, of which the lower division (II, 1) is an "Argillite" formation, con- sisting of clay-slate (including roofing-slate) and a gritty va- riety, designated as wacke-slate. Both of these are described as inclined in their attitude; the wacke having "the same in- clination with the argillite, and diftering widely from the hori- zontal or First Gray wacke." This latter constitutes the second division of the Transition series (II, 2) and consists of "Gray- wacke-slate," described as a fine argillaceous sandstone, and of "Millstone grit and gray rubble," more or less conglomerate. The tliird division (II, 3) comprises the Sparry limestone, found east of the Hudson, the Calciferous sand-rock, identical with that formation in the New York series, and the Transition or Metalliferous lime-rock. Under this latter name, borrowed from Bakewell, were comprised the Birdseyeand Trenton lime- stones ; the localities of which, and some of their organic re- mains, are described by Eaton. § 53. To this succeeds the Lower Secondary series, having at its base, as before, a carboniferous division, (III, ]) described as the " Second gray wacke slate ;" which rests upon the " Transi- tion limerock" (Trenton.) This, which is clearly identified as the Utica and Ijoraine formations, is overlaid by a second Mill- stone grit, which is the Oneida, (111, 2) and is described as passing beneath the calcareous division, (III, 3) which includes the Geodiferous limerock (Niagara) and the Corniferous or Cherty limerock (Lower and U[)per Helderberg.) TRANSITION AND SECONDARY ROCKS OF EATON. E. 27 § ")4. The red sandstones and shales of the Medina, the iron- bearing strata of the Clinton, and the saliferous and g^-psifer- ous marls of the Onondaga, with the overlying Water-lime beds, were by Eaton regarded as a " subordinate series embraced in tlie third regular series." With these red rocks he united cer- tain red l)eds in the Catskills, as well as the red sandstones of the Mcsozoic of New York, Xew Jersey and the Connecticut valley. The disappearance, to the eastward, of the great mass of red str.ita which, in central Xew York, is intercalated at the base of the ilelderberg limestones, is noticed by Eaton. The Cherty Secondary limestone is said to be separated at Bethle- hem Xew York, by only sixty feet of graywacke-slate from the Transition limestone, and to come m contact with it in Catskill in (Jreene county. These limestones of the Lower Secondary se- ries, it was shown, underlie alike the bituminous coals of west- ern Pennsylvania, and the anthracites, which latter were thus re- moved from the Transition series, to wdiich they had been re- ferred by Maclure. Eaton showed, moreover, from their fossil plants, that these coals, of both kinds, belonged to the same geological horizon with the coals of Europe. § 5 J. The coal measures were placed in the carboniferous di- vision of Katon's Upper Secondary series, (IV, 1) which also in- cluded the sandstones of the Erie division of the Xew York scries ; while the sandstones of the Catskill Mountain were made the second division, (IV, 2) and the third (IV, 3) was supposed to be represented by certain coralline limestones in the Ilelderberg. It is obvious that Eaton here fell into errors in the succession of strata, which make it no longer profitable to follow him ; and we now return to the consideration of his Transition and Lower Secondary series. § 56. The Argillite formation of Eaton, which is the lowest division of his Transition series, (II, 1) is said by him to form " the bed and banks of the Hudson," and to appear on the line of section described by him in his " Geological Survey," ibr a breadth of about twent}^ miles, from Williamstown Mountain, in Massachusetts to three miles west of Coboes Falls, on the Mohawk ; where it disappears beneath the overlying rocks. The clay slate of the formation appears to the eastward, in the mountain mentioned, but, along the section, is concealed in great I If m : 1 i ] i ' 1 i ■; \ 1 28 K. SPECIAL REPORT. T. STERRY HUNT, 1875. part beneath the coarser sandy wucke-slate. The two, how- ever, are considered as parts of the same formation, as they both present tlie same angle of inclination. lie is careful, in this connection, to distinguish between the attitude of the stratum, and that of the laminse of the slate, wliicli are de- scribed as forming an angle with the former. (Gcol. Sur., 07.) § 57. This inclined wacke-slate,l)olonging to the Argillite for mation (II, 1) is carefully distinguished from the graywacke slate, the lower member of the First gray wacke formation (II, 2) already noticed; of which it is said "this slate is nearly hori- zontal, and lies immediately upon the inclined edges of tlie Ar- gillite, from Canada to Georgia. It is remarkably curved and bent on the Mohawk between the Cohoes and Scbenectad}', at Saratoga lake, and at the entrance of the Delaware and Hud- son canal." He adds, in a note, that " while European geolo- gists have described a change of direction at the meeting of the Lower and Upper Secondary'," in which the latter rests hori- zontally upon the inclined edges of the former, in iS'orth America this change takes place at the meeting of the Argillite and the First graywacke." (Text Book, page 74.) § 58. The place of this First or Transition graywacke (II, 2 was, according to Eaton, between the Argillite formation (II, 1) and the Transition limestones (II, 3.) Of these latter, the Cal- ciferous eandrock and the succeeding limestones were not shown to rest upon the Argillite ; and in fact, as we now know, are found, in the localities familiar to Eaton, directly upon the Prim- itive gneiss. With them was, however, included the Sparry limestone, known only in the eastern part of the state, lie moreover descriljes numerous larg-e and small massi's of sand- stone and limestone as occurring included between the lamiiue of the Argillite, near the Cohoes Falls, and towards the delta of the Mohawk. These were regarded as small portions of the First graywacke and the Transition limestone; which, he con- ceived, must have fallen into their places between the laminae of the Argillite, while this rock was in a soft state. The shelly (i. e. fossiliierous) Transition limestone described by Eaton as occurring at Becraft's Mountain near Hudson, is now known to belong to his Lower Secondary limestone (III, 3j; it being of Lower llelderbery; ay;e. ^: TRANSITION AND SECONDARY ROCKS OF EATON. E. 29 § 59. Eaton noticert that the acidulous carbonated mineral wa- ter olitaincd bj boring at u doptli of" 480 feet in Albany, is found in the ArgiHite,and sup)p09es thattlie similar waters of Saratoga (now saifl to issue from the Calciferous sand-rock) have a like source. In this connection it is well to recall the acidulous min- eral spring found in South Argyle, Washington county, also in the retiion of the Arjrillito. This Argillite was described as containing a flinty slate or Lydian stone, sometimes green and jaspcr-likc, beds of which abound on the Hudson near Albany, and for forty miles below. (Geol. Survey, pp. 69-70.) § GO. We have seen that Eaton described a Second graywacke, conbtitutinfj the lower and middle divisions of the Lower Sec- ondary ,and made up, like the First, of an underlying slate ([II, 1) and an overlying sandstone and conglomerate; (HI, 2) both of which are declared to be scarcely distinguishable from the members of the First graywacke, except by the fact that they overlie the Transition limestones (II, 3). This Second gray- wacke evidently corresponds to the Iltica, Loraine and Oneida formations of the present n lUienclature, and thus has its recog- nized position in the New " >rk series. § 61. With regard to the i st grayw acko, we have seen that the slate which forms its ii.wer member is said to rest in a nearly horizontal attitude on the inclined Argillite formation, in many localities to the west of the Hudson Kiver. On the eastern side of the river the First graywacke, in its completeness, is largely developed. " It is seen resting on the Argillite, near Col. Worthington's on the Little Hoosic, near the east line of Rensselaer county. On ascending the western hill or ridge, the graywacke-slate, rubble and millstone-grit are found in succession. This ridge extends from Canada through the state of Vermont, Washington county, and Rensse- laer and Columbia counties, and, crossing the Hudson River, forms the vast mountains of millstone-grit called Shawan- gunk." Elsewhere we are told that the rubble or conglomerate of the First 2:raywacke "forms the highest ridges between the Massachusietts line and the Hudson," and that the Shawangunk or White Mountain, of Ulster and Orange counties, forty miles in length, "is a continuation of the grit and rubble of the First m I'-f W 30 i:. SPECIAL RKPOKT. T. STERRY HUNT, 1875. graywackc of Rensselaer county." (Geological Text book, pages 74, 93, 123.) The full significance of these observations of Eaton was not understood til! a much later date, as will appear further on. § G2. Next to Eaton in the order of time we note the earlier publications of Henry Darwin Kogers. The geological survey of Pennsylvania was begun by him in 1836, and was actively carried on for live years, or until 1841. In his fourth i.nnual report, tliat of 1840, we find a detailed ac ount of the for- mations of the south-eastern part of the state. The crystalline rocks included syenite, serpentine, etc., together with gneiss, mica-slate, talc-slate, and "the more or less crystalline lime- stones," of the Chester and Montg(jmery valley, lying between the Middle and Southern gneissic districts and, it was said, "obviously, like the former rocks, belonging to a Primary date." While all these rocks were thus included in the Primary sys- tem, as it was then generally understood, the limestones of tiie Lancaster and Kittatinny valleys, and their accompanying sand- stones and slates, were said to belong to the Lower Secondary or Appalachian series; while the Mesozoic sandstones were called Middle Secondary. The next annual report, in 1841, contains, with regard to the Primary scrip's, only a few points of detail ; and it is not until the final imblication lA' Rogers, in 1858, that we find his later views with regard them, as set forth in the preceding chapter. § 63. Simultaneously with the work of Rogers in I'ennsyl- vania, a geological survey of the state of New York, begun in 1837, was in [)iogre8s. The state was divided into four dis- tricts, of which the first, or southern, wasc(jnfided to Prof. \V. W. Mather, and second or northern to Prof. E. Emmons. The central and western districts were entrusted to Messrs. L. Van- uxem and James Hall ; but their work has no particular bearing on the questions now before us. Messrs. Mather and Emmons set forth their views on the geology of their respective region'^ in various annual reports, but we refer for a full ex[»osition of them to their final reports, of which that of Emmons appeared in 1842, and that of Mather in 1843. § 64. Resting upon the Primary system of ancient crystalline rocks, in northern New York, there were found, according to THE CHA.MPLAIN DIVISION OF EMMONS. E. 31 Emmons, the lower members of the New York Triinsition sys- tem. To these lower members Emmons, as is well known, gave the names, in ascending order, of (1) Potsdum sandstone, (2) Calciferous sandrock, (.3) Cliazy limestone, (4) Trenton lime- stone, with its associated sub-divisions of the Birdseye and the Isle La Motte or Black River limestone, (5) Utica slate, (0) Lo- raine shales, (7) Cirey sandstone, (8) Medina sandstone. These constituted, according to him, the Champlain division of the New York series. The Grey sandstone, which in Jetterson county overlies the Loraine shales, was l)y him regarded as the eciuivalent of the conglomerate of Oneida. This, with the suc- ceeding Medina sandstone, has, by subsequent geologists, been separated from the (Jhamplain and united with the Ontario di- vision; which also includes the Clinton and Niagara tormations. § G5. To the Champlain division, also, Emmons referred certain red and purple slates which, tiiough not i'ound in the counties to the westward, constitute a narrow belt '* which passes through the higher parts of Cohuubia, Rensselaer and Washington counties, and onward through Vermont into Can- ada. It is every wiiere destitute of tossils."' These slates were sup- posed to belong to the J^oraine formation, while to the succeed- ing sandstone was referred the so-called Gray wacke (the Transi- tion graywacke of Eaton,) which forms ranges of hills in the counties just named, "and alsooccui's at Quebec," It is described as being often coarse and brecciated, having a greenish cement, supposed to be derivi'd from "tlie chloritic slate along the east- en\ boundary.'' To this horizon was also referred a reddisii- brown or chocolate-colored sandstone, with interlaminated red shale, stretching along the eastern border of Lake Cham- plain, and to the west of the Taconic range,'" in Verniont. Jie- sides this was a mass of limestone immediately succeeding the red sandstone, traversed with numerous veins of calcite and quartz, which is well seen in Bald Mountain, and is the Sparry limestone of Eaton. This rock, according to Emmons, extends tiirough the valley of l^ake Champlain, on the east side, and is not to be confounded with the more ancient granular lime- stone of Berkshire county. All of the rocks mentioned in this section were said to be without fossils, and to be lithologically dissimilar to those of the Champlain division as seen intheval- I i 32 E. SPECIAL REPORT. T. STERRY HUNT, 1875. ■ i! I Iw I III fr ley of the Mohawk and west of the Adiroudacks ; although tliey were, at this time, unliesitatiiio;ly referred by Emmons to the ui)[)er portion of tliis division of tlie New York series. (Ge- oloifv, Second district, jiages 121-120). § 6t>, The rocks to whicli, in his annual reports on the South- ern district, Matlier had given the name of the Hudson River slates or shales, were by Emmons, in 1842, regarded as a south- ern prolongation of the above stratu from the east side of Lake Champlain. The name of Loraine shales, we are told by him, "is simply a synonym of the Hudson River shales, both terms being occasionally used to designate the same rock. They differ, as has already been pointed out, only in the physical changes which each has sustained. At Loraine they are but slightly removed from a horizontal [jositicm, while along the Hudson River they have been fractured and elevated to a high angle, or a steep dip to the east has been given them." (Ibid, page 281.) In Vermont, we are farther told that the Cham- plain group extends for six miles east of Ilighgate, while "at Slicldou we leave the Champlain group and pass directly to the Taconic system, consisting at its extreme north, in Vermont, of the same masses of slate and limestone as in the counties of Columbia and Dutchess in New York. Taking a general view of the rocks on the east side of Lake Champlain, and those in the same range, both north and south, we find them consisting of the upper members of the Chami)lain group. To the east, succeeds the Taconic system, whose width is from six to twelve miles, made up of the same members which compose it in Berk- shire county, Massachusetts, with the exception of the granular quartz. This general arrangement extends at least to the lati- tude of Quebec, presenting one of the longest formations yet known to geologists." (Ibid, page 322.) § 67. The Taconic system, as at this time defined, included the granular quartz-nx^k and granular limestone of the Primi- tive series of Eaton (T, 2 ; I, 3,). These were by Emmons sepa- rated from the rrimitive schists and gneisses, and united with the Transition argillite (EI, 1) to form what he regarded as a distinct series; which, though not found between the Primary and the New York series, at the outcro]) of the latter in north- ern New York, was sujiposed to be intermediate between the f mathp:r ox new york geology. E. 3o two. It formed tlie Taconio hills of western New England, occupying, as we have seen, a narrow belt between the Primary on tbo east, and the disturbed and eastward-dipiiing rocks, re- ferred to of the Cliamplain division of the Now York series, on the west; tbo boundary between which and the Taconic .system along the Hudson, was not as yot distinctly deiined Ijy Em- mons. The rocks of these two series, it should be remembered, do not occur within the limits o*f the Northern district of New York, which had been assigned to him. § C8. Mather, in his final rei -rt on the geology of the Southern district of New York, which appi»eared in 1843, or the year following that of Emmons, recognized no distinction between the New York series and the Taconic system, which he regarded as nothing more than the Champlain division of Emmons (excluding therefrom the Oneida and Medina sand- stones,) in a modified form. The granular quartz-rock of the Taconic was, according to him, the Potsdam ; the granular lime- stone was the Calciferous «androck, with the succeeding Chazy and Trenton formations ; while the Hudson River Argillite se- ries, including the roofing-slates, represented the Utica slates and the Loraine shales. § 69. The district examined by Mather included the Hudson valley from the crystalline Primary rocks of Washington and Saratoga counties on the north to the similar crystalline rocks of the Highlands on the south. He pointed out what he .called the Hudson axis, extending from Baker's Fal» on the Hud- son river, near Sandy Hill in Washington county, southward by Saratogsi Lake, Glen's Falls, New Baltimore, Catskill and Kingston. This axis "may be traced farther to the south in the Comfort liills of Orange county, between the Wallkill and the Shawangunk rivers, and is probably an extension of that of Pochunk Mountain, on the New Jersey line." It thus skirts the Hudson river for more than one hundred miles. (Geology, First district, pp. 357, 375, 623.) § 70. The course thus defined, which is declared to bo "a line of fracture, and an anticlinal axis," is indicated with more pre- cisenoss of detail in the Fifth annual report of Mather, (page 66,) where, in its northward extension from Orange county, it 3— E. m T 34 E. SPECIAL REPORT. T. STEKRY HUNT, 1875. i-i HI is said that it ''crosses the tShawaiiguiik Mountains with a very acute angle, [)as8eH near Kingston, thence halt' a mile east of the i'all of Esopus creek, hy vSaugerties, alung the ridge hetween Catskill village and the Katei*skill creek on the road to the Mountain JJou.se ; near Madison, three miles north-west of Cats- kill; four miles west of Athens; three miles we*;t of Cox- sackie, and ahout the same distance west of ^'ew Baltimore and Coeymans. Its continuation in Alhany county is seen whore the Normanskill and Mohawk intersect it. It crosses the Mo- hawk a few miles helow the aqueduct, and ranges thence, hy !Saratoga Lake, to Baker's Falls on the Hudson." To the east of this line the strata present characters very unlike those on the west. § 71. This line corresponds to that defined by Eaton between the Transition Argillite and the uucontbrmably overlying Tran- sition Graywacke, a fact which serves to explain the language of Mather, who informs us that "the horizontal and slightly in- clined slates and grits of the Hudson River group lying to the west of tills axis * * '^ were formerly considered as more recent strata than the upturned rocks of the Hudson River val- ley, and as resting unconlbrmably upon them." Me, however, maintained and sought to prove the identity of the rocks in the two regions, though he declared that "the upturned rocks are so much modified in their characters by the causes which have deranged their position, that it requires the strongest evi- dence to convince one that they are no older than the horizon- tal rocks west of the axis of disturbance." In proof of this view he aflirmod that it was possible in many cases "to trace the strata across the axis of disturbance," and, moreover, to lind, in various localities among the disturbed rocks, fossils of the Champlain division, especially the graptolites of the Utica slates. § 72. The strata of this disturbed region dip constantly to the eastward, and often at angles ap) iroach ing the vertical. They are also, according to Matlier, affected by numerous fractures and faults, which " have deranged all the rocks of the Champlain division and packed them together '• * in the utmost con- fusion." " Thev are contorted, broken and wrinkled in almost every conceivable manner," and " the repetitions of the same > 'J MATHER ON NEW YORK GEOLOGY. E. 35 strata with others lying lower and higher in the geological series, and with frequent apparent inversions in the order of superpo- sition, render it almost impossihle to determine, from an exam- ination of the strata on the east bauii of the Hudson, what the real order of superjiosition is. Other difficulties also present themselves, viz: the fossiliferous rooks dip to the east, and a|>- [•arently plunge under those which have been considered of more ancient formation ; and, on the eastern Hank of the Hud- son valley, these plunge apparently under what we have been accustomed to consider very ancient rocks, as gneiss, granite, mica-slate, etc." That these disturbed strata, destitute of fos- sils, often with glazed surtaces, more or less talcose in aspect, traversed in parts by numerous quartz veins, and including many "anomalous rocks," were very unlike the Champlain di- vision as seen in the Northern district, to the south and west of the Adiroudacks, was thus clearly recognized by Mather, who nevertheless believed the two to be equivalents in geological j)osition. § 73. We have next to notice belts of rocks in this region, referred by Mather to the Ontario division of the New York series. First of these, on the west side of the Hudson, is the !Shawany;unk range, extending from the New Jersey line north- eastward a dist lUce of *bity-three miles to Ivoscidale, near Kingston, and regarded as a prolongation of the Kittatinny range of Pennsylvania. The strata of this range are chietly of sandstone and conglomerate, gray or white, and more rarely red, with slaty layers. They are described as resting unconfurmably upon the Hudson Hiver slates, and as contormably overlaid by red slates and marls, regarded as re[)resentiiig the Medina ; tlie sand- Htone itself being su[»posed to be the eciuivalent of the (Jneidu. The dip of this lormation is to the north-west, sometimes at a high angle. It is remarkable for its quartz veins carrying sul- pliuivttetl ores ol' lead, copperaiid zinc; and for its beds of ct)n- glomerate, in which the cemeni is pyrites, ench)sing pebbles and grains of quartz. § 74. Besides this range, Mather noticed to the south-east another conqtosed of somewhat similar rocks, which are traced at intervals from the New Jersey line, by the west of Long J'ond, north-northeast to near Canterbury in Cornwall, Or- 36 E. SPECIAL REPORT. T. STERRY HUNT, 1875. ?r ange county. Tlieae were regarded by Mather, and by Rogers, as the extension of the Green-Pond Mountain range of New- Jersey ; and were supposed by the latter to be of the age of the Mesozoic sandstones whicli are found to the south-cast of them. Mather, however, considered them as the geok)gical equivalents of the 8hawangunk range, which they resemble lithologically ; and described the occurrence of shales with organic re- mains of Lower Ilelderberg age, associated with the con- o;lomerate of this series, at Townsend's iron mine in Cornwall. These sandstones, conglomerates and shales are well displayed in I'ine Hill and Blooming Grove, and in Belvaie and Skunne- munk Mountains, in Orange county. § 75. The important fact connected with this series of rocks is that, according to Mather, similar rocks, consisting of coarse white, gray and greenish sandstones, red and white conglom- erates and red shales, '"are found on the east side of the Hud- son valley, ranging from Fishkill, near Matteawan, through Dutchess, Columbia, Rensselaer and Washington counties into Vermont, in West Poulteney ; a distance of more than 200 miles from their southern terminatioti in New Jersey." These rocks frequently occupy two or three parallel belts one or two miles apart, and are often associsited with limestone in Orange county, as well as in the counties east of the Hudson River; where they rest on the Argillites ot the Hudson River group, and dip to high angles to the eastward ; while in the Highlands they are in contact witli the Primitive gneiss, and have a similar inclina- tion, or are even vertical in attitude. In many instances no- ticed by Horton (the assistant of Mather) in Warwick and Munroe, Orange county, where this sandstone formation (Gray- wacke) occurs on the northwest side of the gneissic hills, "the lines of bearing and dip of the Graywacke coincide with those of the Primitive, and the Graywacke has the appearance of passing beneath the Primitive rock. At the western base of Goosopond Mountain, and of Sugar Loaf Mate, the slate has the same jiosition in reference to the Primitive, and exhibit« pre- cisely the same appearance." § 76. The conclusions of Horton from the study of these rocks, chiefly in Orange county, may be thus summed up: 1°. The slate (Argillite) and the Graywacke of the Hudson IIORTON ON NEW YORK GEOLOGY. E. 37 River are iiiterstratilied with each other, forming a coiitenipo raneous series (A) ; and the limestone of Neeleytown and the hlue limestones of Nevvburg, Munroe, Blooming Grove and Go- shen are interstratilied with this series. 2°. Tliegrit ot Shawangunk Mountain (B) rests unconforma- bly upon the basset edges of the Argillite and Graywacke se- ries. 2°. The grit and Graywacke of Pine Hill, Blooming Grove, Bolvalo and Skunneinui»k Mountains (C) also rest on the same Argillite and Graywacke series (A); whether unconformably is not stated. 4°. The "conglomerate and fossiliforous limestone of Go- shen" (D) are newer than the blue limestones mentioned above, since, like the rocks C, they rest upon the series A. 5°. The limestone at the foot i>f Shawangunk Mountain rests conformably on the Shawangunk grit, and is overlaid by the Graywacke of Deer Park, (the sandstones of the Devon iaii series. (Geology, First district, page 580). These interrupted belts of sandstones, conglomerates and red shales, (the grit and graywacke,) are traced, according to Mather, from New Jersey to Vermont; and although their identity with the Shawangunk range was not certain, they were by him referred, like it, to the Ontario division of the New- York series, (ibid, pages 362-365). § 77. Emmons, as we have seen, did not, in 1842, clearly de- line the limits between the Taconic system and the rocks, re- garded as belonging to the Chaniplain division, which bounded it on the west; the position of the two giving rise, according to liim, to "many doul)T8 and perplexities as regards the true limits of either system." Far from including in the Taconic system the whole of the highly disturbed region along the Jludson valley, ibis system was, at that time, confined to a nar- row belt along the western border of the Primary, while the strata between this belt and the river were still included by Enmions in the Champlain division. § 77A. According to Mather, the rocks of the Taconic system, as thus limited, have tiie same dip and strike as the rocks of the Champlain division, "and apparently overlie theni ;" the di]) of the strata being easterly, and at angles of from 30° to 38 E. SPECIAL REPORT. T. STERRY HUNT, 1875. I \^ 90°. "Although the rocks ull dip in the same general direction, similar strata, at no great distances, are frequently reverseJ in the relative order of their supposition." It was iinp()S3ible to draw any line of deniarkation between the r:)cks of the Ta- conic system and those of the so-called Champlain division, in this region, and Mather was forced to the conclusion that they belong to one and the same series. In his own words, ho con- ceived that " the Taconic rocks are the same in age with those of the Champlain, but modilied by metamoridiic agency and by the intrusion of plutouic rocks." (Geology First district, page 438). § 78. Similar conclusions were reached by 11. D. and W. 13. Rogers, as the result of sections made across portions of the re- gion in question, and set forth in a communication to the Ameri- can I'hilosophical Society in 1841; in which they asserted that the Taconic rocks were identical with those of the Hudson valley, and referred both to the Champlain division of the New York series. They declare that where " the exact order of superposition of these rocks and the Primary can be ex- amined, it is found ; first, that the granular quartz either rests upon or pitclies immediately under the gneiss or granitic rocks ; second, that the limestones lie next in order from the gneiss or granite, either in super or sub-position ; and, third, that the slates next follow." (Ibid, page 423). § 79. Before proceeding further in the description of the Taconic rocks, we may notice the views of Mather and Em- j mons, and of some others who had preceded them, regarding • the crystalline formations, which are found north, east and south oT these, in the state of New York. These crystalline rocks were described by Mather under two heads, the Primary and the Metamorphic divisions. To the former were referred the granitoid, gneissic and hornblendic rocks of the Highland chain, found in Putnam, Westcliester, Dutchess, Rockland and Orange counties ; with which were also classed the similar rocks of Saratoga and Washington counties, included within the northern part of the First district. The rocks of this range, as is well known, are continued, with the same lithologi- cal characters, in the South Mountain range into Pennsylvania; where they constitute the Northern and Middle gneissic dis MATHER ri FlUST METAMORPIIIC (JUOUP. E. 39 tricts of Rogers (§ 12). No attempt was made on the geologi- cal map of New York to trace the limit between these Primary rocks and the succeeding Metaniorphic series. § 80. Tiie n)cks to whicli he gave the name of Metamorphio were divided by Mather into two groups. Of these the tirst and most important is that series described by Emmons as tlie Primary belt, bounding on the east the Taconic range in Ver- mont and western Massachusetts. It enters the state of New York,aci ording to Mather, in the northeast corner of Dutchess county, extending thence along the southea3tern side of the Highland range to the Hudson, and to Long Island, and in- cluding the county and city of New York. The rocks of this belt are described, to the north of the Highlands, as chietiy mi- caceous, talcose and cbloritie slates, with quartzites and more or less crystalline limestones or dolomites; while south and east of the Highlands, in Westchester and New York counties, are found still more crystalline limestones, associated with mica- schists, micaceous gneiss, hornblendic rocks, granite, syenite and serpentine; the latter three being regarded as plutonic rocks. In this Metamorphic series are included, as will be seen, the limestones, mica-schists and gneisses of Manhattan island, as well as the belt of steatite and anthophyllite-rock, with serpentine, found on the western side of the city of New York; which is apparently related to the similar rocks of IIol)oken and Sfaten Island. At Stony Point, on the Hudson, tliehornbIen! Prof. Cook and his associates of the i)rcsent geological survey I" New .Jei*sey have shown to be a fallacy, as those of Emmons in northern New York, and of the geological survey of Canada, hnw long sinci" di'inonstrated for the latter regions. 1^ EMMONS ON THK IMlIMAUY ROCKS. E. 4;; § 85. While he adopted to a very threat extent the views of Niittall and of J-i()i,'ers, .Nhitlier (lid not i\\>\>]\ them to all the crystalline liniestonea. He refers to the view of Emmons that crystalline limestone is an eruptive rock, and says tliat there are many examples in the J'limary rei;ions of \Vashiii<;ton county which serve to demonstrate this, and leave little or iio douht that the rock was " injected in a fluid state." In another locality, a cliit'of white crystalline limestone is said to include "a mass of stratified hornhlendic giu'iss distinctly imhedded in it." (Geoloiry, First district, page 485.) § 86. Emmons, in his final rejjort on the Northern district of Xew York, in 1842, (U'scrihed as I'rimary rhe crystalline rocks of the Macomb Mountains ; to which region the name of the Adirondacks, at first applied to their highest group of liills, has since been extended. It embraces the crystalline rocks of Washington and Saratoga counties, which were included in the Southern district and noticed by Mather. The crystalline rocks of this great Primary region were, by Emmons, divided into two principal groups: 1st, Unst rati tied; including granite, hyper- stliciie rock, crystalline limestone, serpentine and rensselaerite ; '2(1, Stratified ; embracing gneiss, hornblende-rock, syenite and steatite. In a subordinate group were included certain {)or- phyry and traps traversing the rocks of the New York series, (which, in parts of the regic»n, overlie the Primary) and the mag- netic and specular oxides of iron, found in the gneissic and hy- persthenic masses, and, like the 1st group, regarded as unstrati- fied. Granite, according to him, was rare, and was so often found i>assiug into gneiss that he regarded the distinction be- tween the two rocks as an unimportant one, and declared that it was in many cases impossible to determine whether a given r(jck belonged to the one or the other of these. § 87. It should here be noted that Emmons did not accept the so-called metamorphic theory of crystalline rocks, adopted by Nuttall, Rogers and Mather, which maintains gneiss to be the result of an alteration of uncrystalline sedimentary matters, of which process granite is only the last term. The view held by Emmons still finds favor with a considerable school of geolo- gists, according to whom the stratified crystalline rocks are of igneous origin, and owe their banded structure to an arrange- 44 E. SPECIAL REPORT. T. STERRY HUNT, 1875. merit of their mineral constituents by movements while yet in a liquid state, so that gneiss may be deliiied as a laminated gran- ite. These stratified rocks, which Enmions designated by the term Fyrocrystalline, were regarded as igneous, and in no sense of sedimentary origin. Tlie associations of the crystalline lime- stones with tlie granitic and gneissic rocks were such that these too were regarded as of igneous origin ; a view which he main- tained at length, in opposition to the theory of their sedimentary nature supported by Hitchcock, Rogers and Mather. The same view was by him extended to the serpentine and renssel- aerite, so oft^n associated with these limestones. The igneous nature of crystalline or primary limestone was at that time taught by many European geologists of distinction, and a simi- lar view ci the nature of serpentine is still prevalent. § 88. The name of hypersthene-rock, (previously applied to a similar aggregate in the Western Islands of Scotland, by Ma- cuUoch,) was given by Emmons to a formation which occupies the greater part of Essex county, New York, i'orming the highesthills in the district. It was correctly described by him as consisting chietiy of labradorite, fref|uently intermixed witii hyperstheue ; while certain varieties of the rock contained also hornblende, epidote, mica and garnet. An unstratified rock like granite, it was, like it, declared to be intermixed with and pene- trated by crystalline primary limestone, marked, as elsewhere in the Adirondack region, and in the Primary rocks of the High- lands, in the Southern district, by pyroxene, hornblende, scapo- lite and apatite. (Geology, Second district, pages 89,40), § 89. We have already set forth the views of Emmons re- garding the Taconic and New York systems, as taught by him in 18-42. In 184G, aitpearcd his volume on the "Agriculture of New York," in which, while giving a summary of the geology of the whole siate, he revised his opinions on the Taconic and the Chaniplain rocks. The former were, in 1842, restricted to a narrow belt between the Primary rocks on the east and the New York series on the west; this position giving rise, in the language of Emmons, "to many doubts and peri)lexities as re- gards tlie true limits of either system." The disturbed strata on the east side of the Hudson, thus referred by Emmons to the Utica and Ijoraine formations, could not, according to EMMONS ON THE TACONIC SYSTEM. E. 45 Matlier, be separated from tlie Taeonic, wliicli he tlierefore re- garded as one with theChumplain division. In 184tJ, Emmons himself recognized this identity, but extended to the whole the name of Taeonic. He explained that he had, in 1842, referred the Taeonic roofing-slates to the ujiper [Kirt of the Champlain division on account of some markings on tliem, whiers of the Champhiin division were also declared to rest unconformably u{)on tlie Taeonic slates, to the east of the Hudson. In his volume of lS4(i, Emmons de- scribes a section from Greenbush, on the Hudson, eastward to 46 E. SPECIAL REPORT. T. STERRY HUNT, 1875. Chatham Four-Corners, the rooks, a scries ol" eastward-dipping shitea, limestones and quartzites, being represented throughout as laconic, witii the exception of small outliers of Loraine shales and Calciferous sandrock, near the Hudson. In another section across the Hudson, at I'ouglikeepsie, the strata on both sides are called Taconic, and are rejjresented as succeeded, one mile west of the Hudson, by Hudson River (Loraine) shales, (loc. cit., plate XVIII.) The continuation of this section east- ward from Foughkeepsie is also designated by hini as Tacouic. By com[)aring these data with the geological map of New York, and with the statements of Mather, given above, it is clear that the Taconic slate formation in eastern New York was co-extensive with the disturbed, altered and anomalous Hudson River group of Mather, and that the included and un- derlying limestones of the legion were, in like manner, the lime- stones of the Taconic system of Emmons. § 93. We have next to consider those overlying rocks which Mather, in this region, referred to the Oneida and Medina for- mations of the Ontario division. In 1842, Emmons placed at the summit of the Loraine what he called the Gray band, which he considered as the equivalent of the Oneida, and in- cluded this, with the Medina, in the Champlain division; but in 184(j he transfer''ed the Medina to the Ontario, making the Champlain division to terminate with the Gray band or Oneida. Thus, when Mather speaks of the rocks in ijuestion as belong- ing to the lowei part of the Ontario division, and Emmons as- signs them to the upper part of the Champlain, it will be un- derstood that both refer them to the same horizon ; the latter geologist including in the Oneida certain red shales regarded by Mather as pertaining to the Medina formation, § 94. Mather, as we have seen, traced these overlying rocks, with the help of Rogers and Horton, from New Jersey, through Orange county. New York, to the west bank of the Hudson river, and thence, crossing into Dutchess county, along the east- ern side of the Hudson, through Columbia, Rensselaer and Washington counties, to West Poultney in Rutland county, Vermont, near the head ot a-.,!.e Champlain. Emmons, in 1842, referred to the Oneida the sandstones occurring farther north, along the east side of this lake, in the towns of Addison, Char- 1 ( a I b t( ni EMMONS ON THE TACONIC SYSTEM E. 47 lotto, Burlington and Colcliester ; while the liniestoiies of St. Albans, Swanton and llighgate were suppotJed by him to be- long to the summit of the Loraine. lie further pointed out that these rocks, (regarded collectively as belonging to the summit of the Champlain division), extended southward from Vermont, through the eastern counties of New York already named, where they had been studied and described by Mather, and northeastward through Canada, as lar as (Quebec. § 95. Between 1S42 and 1840 the views of Enunons vvith re- gard to these rocks had undergone a complete change, and he now transferred them to the lower part of the Champlain di- vision, and regarded them as a modified form of the ('alcifer- ous sand-rock of the Mohawk valley, which, to the eastward, he declared to include various forms of rock, and to be "pro- tean" in its characters. To one of these varieties he referred the red sandstones of Addison, Charlotte and Burlington, with their interstratitied red and chocolate-colored slates, and de- clared that these sandstones, through an admixture of carbon- ate of lime, pass into a gray calcareous sandstone, forming the upper part of the series ; while beneath the red sandstones were beds of a blue compact limestone, sometimes fossiliferous. This limestone, he declared to be the lowest member of the se- ries, and to rest directly upon the Taconic i)lack slate. § 90. This whole formation was supi)Osed by PJmmons to oc- cupy the position of the so-called Calciferous sandrock of northern New York, which is beneath the Chazy limestone and above the Potsdam sandstone. This latter formation, accord- ing to him, was wanting in eastern \''ermont and eastern Xew York, as well as in the valley of the Mohawk, where the Cal- ciferous rests directly on the Brimary. An irregular belt of this motlitied and protean Calciferous sand-rock, acci rding to Emmons, is traced from the Canada line, through eastern Ver- mont, into Xew York. "Ln the counties of Dutchess and Orange it forms an imperfect belt, in Columbia, Rensselaer and Washirigton counties its continuity is still more broken. It occupies in the last three counties the knobs, as at Green- bush, Urcenwich and Whitehall. These knobs lie contiguous to the Hudson; it is, however, still found sparingly twenty miles east of the Iluilson river, an at Iloosic, and, as I now be- I 48 E. SPECIAL UEPORT. T. STERRY HUNT, 1875. lieve, near Pownal, Vermont. * * * Probably this broken ranL'"c or belt runs obliquely across Columbia and Dutchosg counties, and thence onward into Orange, crossiniii; the Hudson I'iver a few miles above Newburg. We can hardly avoid the inference that this belt was once continuous, and formed an important mass, overlying the Taconic slate." * * * In the Jfudson valley insulated patches of these rocks, sometime8 limited to a few acres, and sometimes miles in extent, are met with, often forming tlie highest points in the region. In favor- able localities they occupy a jiosition not to be mistaken, and rest upon the slates of the Taconic system. The liniestone, which appears at the base of this series, reposes upon the upturned edges of the Taconic slates, as is seen in many quarries. As the result of the great fractures and disturbances in this re- gion, the rocks of the ('alciferous series are also sometimes found "in the valleys, outcrop})ing from beneath the Hudson Uivcr (Ijoraine) slates which have been preserved from de- nudation." (Agriculture of Xew York, pages 118-122.) § 97. With regard to the overlying rocks, which form the up- per members of the Champlain division, the Utiea slate has, according to him, "but a slight claim to the distinction of an independent" formation, constituting, as it does, the transition from the Trenton limestone to the Loraine shales ; and in or- ganic remains, and in other characters, partaking more of the characters of tjie latter. In Jefferson and Lewis counties he remarks that there is an alternation of strata having the as- })ect of tlui Utica, with the Loraine shales, which latter, in their upper part, alternate with the thick-bedded sandstones of the (ilray band, already mentioned, so that it is not easy to define the liniits of the two. These heavy beds of the Loraine are seen in the valley of the Rondout in many places east of the High Falls, on the Hudson and Delaware canal, and to great ad- vantage at their northern outcropping along the termination of the Helderberg range, v, ; ere appear alternating beds of sandstone and black slate, the latter from twelve to eighteen inches in thickness. About 700 feet of these strata are there exposed, with a slight dip to the south-west. "It is here al- most destitute of fossils, and in thisresjiect resendjles the beds which occur in patches upon the east side of the Hudson, along ROCKS OF THE CHAMPLAIX DIVISION. E. 49 the Western (Boston and Albany) niiUvay. These latter beds may be clearly di-itinguifihed from the slates and shales of the Taconie system ; they neither conform with them in dip nor in strike, and, except in the immediate vicinity of the great north- ern fracture of tlie Hudson valley, their di[) and disturbance are not excessive." These rocks are said to forma small range be- tween Chatham Centre and Chatham Four-Corners, where they lie in deep troughs, and are exposed in the railway cuttings." (Agriculture of Xew York, pages 128-125, 128.) § 98. According to these statements of Emmons, we have then in the region of sedimentary rocks, along the valley of the Hudson, three distinct series of strata: I. the slates and limestones of the Taconie series ; II. The sandstones, slates and limestones belonging to the Calciferous sand-rock of the Cham- plain division, resting, in ajijiarent unconformity, ujion the for- mer, and partially removed by erosion before the deposition ot III, a series of shales and sandstones belonging to the sni)erior portions of the Champlain division, which have, in their turn, been to a great extent eroded, but are found in patclies over- lying, unconformably, alike the strata of I and of II. § 99. This condition of things im})lie8 that there occurred a change of level immediately preceding the time of the Utica and Loraine formations, (IIF,) which allowed these to be depos- ited not only on the Trenton limestone, but also on the older se- ries, (T and II.) That such was really the case is evident from other facts. The Laurentian region of the Adirondacks and Laurentides was not, at this time, as has been so often said, the nucleus of a growing continent, but one of the higher parts of a subsiding one, and the deposition of the rocks of the Cham- plain division was marked by more than one period of disturb ance. Upon its ancient gneiss we find reposing directly, in in different localities, the Potsdam, the Calciferous, the Trenton and the Utica formations. The deposition of the Trenton marks a time of subsidence, during which, along the Laurentides, the deep sea extended far and wide to the north, and the marine limestones of the Trenton, overlapping the lower members of the Champlain division, were deposited over the regions to the north of Lake Ontario and of the lower St Lawrence, (and as far northeastward as the basiu of Lake St. 4— E. If i 50 E. SPECIAL REPORT. T, STERRY HUNT, 1876. I John, on the Sagueiuiy,) directly upon the submerged Primary or Euzoic rocks. § 100. After this period, and betore the succeeding time of the deposition of mechanical sediments, extensive movements took place in the regions of the Ottawa valley and Lake Cham- plain, which allowed tiieso sediments to he laid down alike on the I'rimary rocks and on the older members of the Cluimplain division. Evidence of this can be seen on the geological map of Canada, where, on the northern border of the Ottawa basin, and immediately south and east of the city of that name, is shown, in the counties ot Carleton and iiussell, an isolated patch of Utica slates, overlaid with gray calcareous sandstones, holding the fossil remains of the Loraine and associated with red shales. This outlier, which has its greatest length, about twenty miles, from east to west, reposes trausgressively alike upon the Calciferous, Chazy and Trenton formations, all three of which, with a slight eastward dip, towards the centre of the basin, ajipear successively, in passing from west to east along the southern border of this unconformably overlying area of the newer strata of the Chamjdain division, which are here let down along the north side of an east and west dislocation. (Geology of Canada, pages 118, 127, 1(35, 219.) § 101. Ennnons has described an analogous occurrence in the valley of Lake Cham])lain, where, in Essex county, near Split ivock, on the south side of Whallon's bay, the Utica slates overlap the older members of tl»e Champlain scries, and " rest visibly upon the Primary" or ancient crystalline rocks of the region. (Geology, Second district, page 278, and plate VIII, section 4.) § 102. In 1855, ajipeared parts I and II of the "American Ge- ology " by Prof. Emmons. The second of these is devoted to an exposition of the Taconic system and of the Champlain division of the New York series, and may be sup])Osed to contain the author's final conclusions with regard to the imi)ortant ques- tions raised in his publications of 1842 and 1846. In 1842 he included in the Taconie system the granular limestones of Stockbridge, the granular quartz rock, the so-called mag- uesian 8lates,and the sparry limerock, besides a group of strata, not very clearly defined, designated by him as the Taconic EMMONS ON THE TACONIC SYSTEM. E. 51 slates ; the order of succession aniono; all these beins:, accord- ing to Emmons, unsettled, or "at least not clearly establislied." The line of deniarkation between the Taconic slates (the Tran- sition Argillite formation of Eaton) and the Xew York series was. also undetermined, and the roofing-slates of Iloosic, and some other localities in that region, were then referred to the latter, in deference to the opinions of his colleagues, though, as he tells us in 1846, contrary to his own judgment. Certain organic forms, resembling the graptolites of the Utica forma- tion, found in these slates, were, in 1842, regarded as evidence that they belonged to the New York series, but subsequently Emmons came to regard them as marine plants, of wliich he describes some with narrow and others with " wide fronds.'' One of these supposed plants from Hoosic was figured by him in 1846, under the luime of Fucoides simplex. (Agriculture, New York,}»age 71, and pi. XVII, tig. 1.) This, according to Hall, had been previously named by ^•Aton, Fucoides secalinus, and wasl)y Hall, in 1865, called Grridge limestone, a great variety of other rocks. Among these were coai*se greenish chloritic sandstones, gray sandstones; limestones, gray and silicious, blue and com- pact, and sparry and brecciated ; besides coarse and fine slates, green, black, red and chocolate-colored, together with tine- grained n)ofing-slates. (Agriculture, New York, page66.) Above this heterogeneous group, included under the common name of Taconic slates, was placed a black slate, sometimes including cal- careous beds, which was regarded as the summit of the Taconic 52 E. SPECIAL REPORT. T. STEIIRY HUNT, 1875. i system. It was in this slate, on Bald Mountain, in Washinoj- ton county. New York, that were found the trilobites described by Emmons as Atops trilineaius and Elliptoccphala asaphoides. (Ibid, pa^e 64.) lie afterwards supposed that tliere are in the region described, on the frontiers of New York and Massachu- setts, roofiiiir-slates at two horizons in the Taconic system ; tlie one, a tine blue slate, occupying a position lu'low the sparry limestone, and the other above this limestone, including the slates of Iloosic, which yield the graptolitic forms already noticed. (Amer. Geology, II,pages 39-41.) § 104. In 1855, Emmons proposed to divide the Taconic sys- tem into two parts, which he called respectively Lower and Ui»per Taconic, and between which "the line of demarkation is tolerably well defined." The Lower Taconic includes the Granular quartz rock, at the base, the Htockbridgc limestone, with its associated Magnesian slates, (to which the name of tal- eose slates was then given,) ajid terminates with the similar slate overlying the limestone. (Ibid, TI, i)age 12.) Further (m, he describes with some detail, the Lower Taconic series as seen in Williamstown and Adams, in Berkshire county, Massachu- chusetts. The lowest division of this series has, at its base, a conglomerate of rounded and angular pebbles of quartz in a talcose paste. This, in some points, rests upon a granitic rock, of which it then includes the fragments. Succeeding this there are several repetitions of quartzose sandstones and con- glomerates, with soft talcose slates, iiaving an aggregate thick- ness of about 1,200 feet, which are well seen in Oak Hill, de- scribed as a synclinal mountain rising 1,700 feet above the val- ley of the Iloosic. Above this comes the Stockbridge lime- stone, 500 feet in thickness, and more or less interlaminated with the talcose slates. 2,000 feet of similar slates, overlie the limestone, and are seen in Saddle and (iraylock Mountains; thus making the entire thickness of the Lower Taconic series in this region about 3,700 feet. (Ibid, II, pages 15-18.) § 105. The same succession and similar characters are b^- Em- mons ascribed to the Lower Taconic rocks in their southward extension through Pennsylvania, Virginia, North Carolina Tennessee and Georgia. He has given the details of a section which is well displayed at the Warm Springs, in Buncombe LOWKR AND UPPER TACONIC SERIES. E. 63 county, North Carolina, on the Frcncli Broad river. The Lower Taconic strata rest unconforniably upon tlie ancient gneisses, (which here dip to the south-east,) and are inclined to the west, the measured thickness being about 3,C00 feet. (Amer. Geoloijy, II, page 24.) § 106. In his "Manual of Geology," published in 1860, the Lower Taconic is described, in general terms, as cou- pisting of a conglomerate at the base, succeeded by three masses of quartzite or sandstone, separated by talcose slates; tbe upper quartzite being often vitreous, while the lower is a sandstone. To this succeed, as before, the granular limestones, with their associated and overlying slates, (including some roof- ing-slates,) the total thickness being about 5,000 feet. § 107. The Upper Taconic series is very distinct in its charac- ters from the Lower Taconic, and comprises the various rocks which have been described as l)elongiug to the Taconic slates. It has, at its base, coarse slates and eandstones, which aregreeii- ioh in color, the masses often resembling a greenstone, and lieing " rather chloritic than talcose." Chlorite, and " perhaps tbe de- bris of hornblende" are said to be present in these rocks, and a chloritic matter is described as forming in many cases the paste of the sandstones and conglomerates, which belong to the base of this series and often rest upon the crystalline rocks. The higher part of the Upper Taconic is said to be very variable or " protean" in character; including brown- weathering calcareous sandstones and olive-colored sandstones, beds of quartzite, with green, purple and red-roofing slates, blue limestones and spariy limestones; while towards the summit are conglomerates with black shaly limestones, the series terminating with a fine black slate. This description niaj' be compared with that previously given of the Taconic slate grouj). (§ 103.) The upper part of this Upper Taconic series is tbssiliferous, containing remains uf graptolites, fucoids and crustaceans. (American Geology, II, pages, 12, 13, 50.) § 108. The Upper Taconic series is displayed in a section from near Comstock's Litndinsi;, in Wash iny; ton county, New York, eastward for ten miles to Middle Granville. The series, (hav- ing an average dip of 40^ to the eastward,) begins, to the west- ward, with thin black shttes, and ends, to the eastward, with 54 E. SPECIAL BEPORT. T. STERRY HUNT, 187o. ii thick-bedded greenish chloritic 8andstone8 and conglomerate!". Tliere is in this series no representative of the granuhir (piartz ites, the limestones, or the talcose slates of tlie Lower Taofwiic, and " the roofing-slates of Columbia and Rensselaer counties are absent." To the westward of this section, at Comstock's Landing, the Potsdam sandstone is seen to rest upon the gneiss, iind jiasses eastward below the overlying Calcil'erous saiidrock and Chazy limestone. Further eastward, the Calcilerous, with its i-liaracteristic tbssils, is seen to rest unconformably upon the beds of the Taconic slate. The Upper Taconic series, it will be un- derstood, here makes its apjiearance from beneath the lower members of the New York series, by which the contact of the Primary gneiss with the Upper Taconic rocks is concealed. (American Geology, II, page 52.) § lUO. The Upper Taconic rocks in this section dip to the east- ward at an angle of about 40°, so that the black slates, at its western end, seem to pass beneath all the other members, and the green sandstones, at the eastern end of the section, appear to overlie all the others. This is directly contrary to the suc- cession alroady given, where the green sandstones are declared to be at the base, and the black fossiliferous slates at the sum- mit of the series. This apparent inversion is, as we liave al- roady seen, the general condition of the stratif '^d rocks ak)ng tiie eastern base of the Athintic belt farthei southward, in New York and along the Blue Ridge, as described by Rogers ;ind by Mather. The latter, as shown in § 72, declares that along the eastern border of New York, in the Southern district, the newer strata of the Hudson River slates dip eastward at high angles, apparently passing beneath the older ones, which in their turn seem to plunge beneath the ancient gneisses. § 110. This condition of things, (which applies alike to the Lower and the Upjter Taconic rocks,) was described by Emmons in 1841, when he declared that "their present position is an inverted one ;" the newer rocks, or those to the west, diji east- wardly beneath the older, or might evi'U })ass beneath them, provid(!d they were prolonged in that direction." He sup{iosed tiiat the newer portions of the series might have been origin- ally contined to the western parts of the area, and never have extended so far east as to cover the basal beds near the I'rimary THE Ul'I'KK TACONIC ROCKS. E. 55 gneias. lie fivrthermorc supposed the movement, which had given to the whole succession an eastward dijt, had heen accom- panied by a series of dislocations, with uplifts on the eastern side of the faults. He remarks, in this connection, that "the force which breaks the continuity of the strata exerts its maxi- mum power nearest the mountain-chain,'' and notes that in the Williamstown section (§ 104) not loss than tive distinct disloca- tions of this kind may be observed in a breadth of a few miles. (Agriculture, New Yotk, [i. (51, and Amer. Qeol. II, i'i». 48-4t).) Such a condition of things is completely analogous to the great parallel faults, with upthrows on the south-east side, described by AV. B. Rogers, and by Lesley, in south-western Virginia, by which the carboniferous rocks are made to dip to the south-east, apjiarontly beneath nmch older strata. § 111, The Granville section of the Upper Taconic rociks, al- ready noticed, is supposed by p^mmons to havea total thickness of not less than 25,000 feet, but it is evident that dislocations like those just described, which may give rise to repetitions, must add greatly to the difficulty of measuring such a iieries of strata. Those Upper Taconic rocks are traced b}'' Emmons southward through Washington, Rensselaer and Dutchess counties, and are said It}^ him to cross the Hudson below Poughkeefisie, passing through Orange county, into New Jersey, and thence to Pennsyl- vatiia and Virginia. In tlie latter state a section of these rocks is described near Wytheville, and another from Abingdon, on the road leading to Taylorsville, Tennessee, in each of which both the Ujtper and Lower Taconic rocks are declared to be well disy»layed. (Amer. Geology, II, pages (>1-61.) § 112. The reader will note that in the account of tlie Taconic system by Emmons in 1842, tiiere is no description given of the gr3at mass of strata which make the Upper Taconic, as defined by him in 1855. There evidently existed in his mind at this earlier date much uncertainty, which is reflected in his writings. Thus, in his report of 1842, the rocks of the Taconic system were declared to extend through the eastern counties of New York, from the Highlands, beyond whicli "they are found stretching through whole length of Vermont, and into Canada, as far as Quebec." (loc. cit. page 130.) In a previ- 66 E. SPECIAL KEI'OHT. T. STEUUY HUNT, \Hl'). ous chapter, in the same volume, we are told, (page 121) under the head of the New York system, that a belt of deep red and purple shales, i)as8ing into a fine-graMied gritty sandstone, ex- tends throuy-liout these same counties in New York ''and onward through Vermont into Camida.'' No locality in Canada Wiis indicated, hut these slates and sandstones were relcM-red to the Loraine shales, of which they were considered a local variation, unknown in the valley of the Mohawk; while a greenish chlo- ritic sandstone or breccia, described as a tyj»ical Graywacke, (which is placed at the summit of the Loraine,) is said to be the material used at Quebec for the construction of the I'ortitioa- tions of the city (page 12').) Farther on in the same volume, tiie sandstones (Graywacke) of Addison, Vermont, as seen in Snake Mountain, and those of Charlotte in the same state, are described as gray, or reddish-brown, and sometimes, like their as- sociated slates, as having a greenish chloritic coloring. These sandstones anrl slates of Charlotte are spoken of as belonging to a range extending from Columbia county. New York, to the Canada line, and as occupying a position immediately below the Medina sandstone, or at the summit of the Loraine shales; the limestones of the Chazy and Trenton apjioaring to dip be- neath the Graywacke series. (Pages 280-282.) § 113. Near the city of Quebec, with the geology of which Emmons was familiar, there are, besides the ancient gneisses, two series of rocks ; one the nearly horizontal strata of the New York series, including the Trenton, Utica and the overly- ing typical Loraine shales, (all of which were there recognized by Emmons); and the other, the highly inclined group of strata which consist in their upjier part of red and purple shales, and are terminated by the greenish chloritic sandstones of Sillery, which are those used in the construction of t)ie fortifications of (Quebec. These rocks are tracsed from this locality south-east- ward, to the frontier of Vermont, along the western base of the hills of crystalline rock, and there is nothing throughout the whole extension which resembles the cpiartz-rock or the lime- stones of the Lower Taconic series. It seems, therefore, im- possible to come to any other conclusion than this, — that the Taconic rocks, which were by Emmons, in 1842, declared to ex- tend from Vermont to Quebec, are the same with those which THE UPPEK TACUNIC R0CK6. K 57 lie t'lsewlicre, in the same volume, de^*cril)es as rocks belonging to the summit of the Ch;implaiii division, uinl having the same distribution. This conclusion is further strengthened by the fact that what he described in 1855 as the Upiier Taconic se- ries has actually been traced from Vermont, along the line just indicated, to the city of (Quebec, the vicinity of which affords a characteristic section of much oi the series. The student of the works of Emmons will iind in them other examjilus of apparent discrepancies and contradictions, which arc, however, easily explained by the disjointed and fragmentary torm of his writings ; in which unity, method and literary skill are, un- fortumitely, wanting. These defects have contributed not a little to the undeserved neglect with which his very valuable contributions to American geology have hitherto been uenerally treated. § 114. In 1846, as we have already noticed, the grny, reddish- brown and greenish sandstones and slates of Addison, Char- lotte, Burlington and St. Albans, (which, like the similar ones of Quebec, were, in 1842, referred in one chapter to the summit of the Loraine shales, and in another chapter apparently con- founded with the Taconic,) were regarded as pertaining to the Calciferous sandstone. This was described as a formation protean in its aspects in this eastern region, and was traced, as we are told, throughout the state of V ermont and the eastern counties of New York, till it crosses the Hudson river a few miles above Newburg and passes, as an interrupted belt, through Orange county. (Agriculture, New York, pages 120- 121.) It was not at this time clearly distinguished from the Taconic slates, upon which it was said to rest, and when later (in 1855) the chief })art of these slates was raised to the rank of a distinct series, under the name of Upper Taconic, flie greenish chloritic sandstones of tiiis region were included therein. The red sandstone of Burlington was now declared to be Potsdam, though some of the beds associated witli it were still included in the Calciferous. ( Amer. Geol., II, pp. 88, 128.) Subsequent studies in this region help to explain this confusion, by showing that these rocks, whether called Loraine and Oneida, or Calciferous and Potsdam, are but parts of the Upper Taconic series, and are the same with those which 58 E. SPECIAL REPORT. T. STERRY HUNT, 1875. I Matlier, in the southern part of their extension, referred, in 1843, to u horizon nearly coinciding with the highest of those just named , namely, the base of the Ontario division, includ- ing the Oneida and Medina formations — the red slates being, ac- oniing to him, above and not below the sandstones. § 115. Emmonts, in liis successive works, makes no allusion to his repeated clianges of opinion with regard to these rocks, so that the student who has not, with critical care, followed their history in his i)ages, fails to find the Key to the contradictions, both real and ap[iarent, which they contain. In his "American Geology," (li, page 88,) in treating of the red sandstone of east- ern Vermont, which is there siioken of as Pott dam, reference is made to "the error which has been committed" in regarding this rock as the Medina sandstone; leaving the reader to infer that the error was committed by some geologist other than the writer, ^o further reference is there made by Emmons to his earlier views, and his fubserpient publications throw but little additional light on the Taconic system. In his report on the " Geology of the Midland Counties of North Carolina," (lSo(),) i)ages 43-72, will, however, be found some few details on tlic Taconic rocks in that region ; and his " Manual of Geology" (1860) may be read with advantage in this connection. £ 116. It is proper, in this place, to notice the views and the observations of the late Prof C. B. Adams, who, in a communica- tion to eriod of the Medina sandstone and the Clinton group." (Proc. Anier. As- Bociation of Geologists, Boston, 1840 ; iti Amer. Jouriial of Sci- ence, [-2] V. 108.) § 118. The Red sand-rock of this region is, in its turn, over- laid by a scries of limestones, which were noticed bv Adams, and subseqently described more particularly by Prof. W. B. Rogers. In following the sections from the western base of Snake or of Buck Mountain, he declan's that "we ascend through the varicHis divisions of the Matimil series, from the Trenton to the top of the Hudson River group, * * * eueh marked by cliaracteristic fossils, and all maintaining a nearly uniform the latter, we find a scries of red iind idstones and shales, of ij-reat tl cr Taconic) ; and, second, that of the conversion of this series, by igneous agency, into the granular quartz-rock and the granular limestone of the Lower Taconic, and the consei^uent Levant age of these latter. The sec- ond proposition, although accepted by Hitchcock in 1860, does not appear to have been supporteil by Rogers. § 123. We have seen that Mather regarded the crystalline strata of southeastern New York as altered or Metamorphic rocks of the Charaplain division, (§§ 81-82,) and that he ex- tended this view to the similar rocks of western New Eng- land, with which they are continuous. These gneisses and crystalline schists, which constitute the lower division of the Primitive series of 'JJaton, and were called I'rimary by Em- mons, can be traced over the greater part ol New England, and form the chief portion both of the Green and the White Mountains. Eaton, although familiar with the rocks of west- ern New England, does not appear to have studied those of the White Mountains, nor liad they attracted the attention ot 62 E. SPECIAL REPORT. T. STERRT HUNT, 1875. V Mather. In 1844, Messrs H. D. and W. B. Rogers, in an essay upon tlieir geology, state that these mountains had previously been regarded as belonging to the "so-calleci primary periods of geological time." They however extended to them the no- tions of Mather, and suggested that the crystalline rocks of the region were altered paleozoic strata, possibly of the Matinal di- vision, (Utica i'-'^-^ Loraine,) but more probably belonging to the Levant division, which included the Oneida, Medina and Clinton formations of New York. The gneisses bore, in the opinion of these observers, some resemblance to the sandstones of the lower part of this division, and they also found, in cer- tain beds among them forms, which were conceived to be the remains of crustaceans and brachiopods, of species belonging to the Clinton formation. (American Journal of Science, [-)!, 411). . In 1847, (Ibid, V, HO,) the same observers announced that they no longer regarded these forms as of organic origin, but did not, however, retract their previously expressed opinion that the crystalline stratified rocks of the White Mountains are of paleozoic age. § 124. Charles T. Jackson, to whose labors the geology of New England is much indebted, published in 184L), his report on a geological survey of New Hampshire, in which he main- tained, (in op])ositi()n to the opinion of tiie MessiJ. Kogers,) that the White Mountain^ constitute an axis of Primary rocks, granite, gneiss and mica-schist, successively overlaid, both to the east and the west, by Cambrian and Silurian rocks. These, on the western side of the axis, in Vermont, have,, according to him, been changed by the action of intrusive serpentines, and intrusive qnartzites, which altered the Cambrian strata into the gneissic rocka of the Green Mountains, and converted a portion of the fossiliferous limestones of the Cl.aiiiplain val- ley into white marbles — the Lower Tacouic limestones of Em- mons. (Loc. cit., pages 160-lil2). In the next chapter it is proposed to trace the history of geological investigation in Canada. CHAPTER III. mSTORTCAIi SKETCH, CONTINUED. § 125. Ilavint::; given in the preceding cluipter the history of geological investigation during the first half of this century, so far as regards the ancient rocks under discussion, from Vir- ginia northward to the confines of Canada, we now proceed to a consideration of the lahors of the (leological Survey of that country, the ofllcers of which have continued the work of the ArnH. lean geologists already mentioned, and have greatly ad- vanced our knowledge of these rocks. In this connection, also, will he discussed the geology of Lake Superior. We liave already seen (§ ol) that Eaton, as early as 1832, had recognized the existence of gneissic rocks like those of the Adirondack Mountains, extending from that region to the vicinity of Alontreal, and also to Lake Huron and Lake Sujie- rior. We find, moreover, that Emmons, in 1842, liad traced the rocks of the Champlain division from the valley of the lake of this name to Montreal and Quehec. The early work of Baddeley, Bigsl>y and Bayfield in Canadian geology de- serves honorahle mention in this connection, and the observa- tions of the latter two, so tar as Ihey bear u})on the ques- tions before us, will be noticed farther on in the chapter. [E.— ()3] 64 E SPECIAL REPORT. T. STERRY HUNT, 1875. § 120. The Geological Survey of Canada was organized in 1842, at which time Mr. (afterwards Sir) William Edmund Lo- gan was appointed cliicf geologist, and Mr. Alexander Murray his assistant. The views of Jjogan on the geology of Canada at that time are emhodied in an olHcial letter, accom[)anied by a preliminary report, dated December, 1842. These, however, wore not [)ublished until 1845, when they appeared, with some explanatory foot-notes, in a volume, together wnth the report of the labors of Messrs. Eogan and Murray for the year 1843, § 127. In the letter, and the preliminary report just alluded to, Logan distinguishes a series of 'Trimary and Granite rocks." elsewhere described as " a range of syenitic hills of a gneissic order," bordering the St. Lawrence on the north, and connected by "the very narrow isthmus of the Thousand Is- lands " with the siniilar rocks in northern Xew York. To the westward, these Primary rocks were said to form the northern shores of Lakes Huron and Superior, and to stretch along the north side of a great basin of " Transition rocks," chieily limestones, occupying the St. Jjawrence valley. Logan farther tells us, that from beneath the southern edge of the Transition trough, "there rises an important formation of pyritiferoua clay-slate, * * which is widely spread over the East- ern Townships, south of the St. Lawrence." In the foot-notes to this preliminary statement, it was however said that these clay-slates were supposed, from farther investigations, to be of more recent origin than the Transition limestone, and " pro- bably above, instead of below it, in geological position." Over- lying these clay -slates were roticed fossiliferous limestones of unknown age, found on the river Famine, a tributary of the Chaudiere, and on the river St. Francis, near Sherbrooke. § 128. Referring to the contorted rocks of Point Levis, op- posite to Quebec, Logan was " inclined to the opinion that they come out from below the flat limestones of the St. Lawrence," though he added in a foot-note at the time of publication, (in 1845) ihat "the accunmlation of evidence points to the con- clusion that the Point Levi& rocks are sujierior to the St Law- rence limestone." In this latter view of these rocks near Que- bec, he had accepted the conclusions of Emmons, announced in his report published in 1842 (§ 65); while, as regards the clay- PRIMARY ROCKS IN CANADA. E. 65 Blatc formation, — supposed by Logan to be a prolongation of tbe Argillite formation of Eaton i'rom eastern New York and Vermont, — be adopted tlie opinion expressed by Matber in bis report of 1843 (§ 68). § 129. Tbe publisbed results of tbe geologists of New York and rennsylvania were at tbis date familiar to Logan, as is made more evident in tbe first portion of bis report of progress for 1843, publisbed witb tbe i)rt'ceding, in 1845. In tbis he describes tbe various members of tbe New York series as traced nortbward tbrougb tliese States into tlie great Transi- tion trougb of tbe St. Lawrence, and remarks tbat "tbese fos- sil iferous formations, wberevor tbey bave lieen found in actual contact witb tbe rocks beneatb, appear to rest upon masses of tbe Primary order. But the geologists of New York consider tbat tbey bave evidence of tbe existence of a series of non- fossiliferous sedimentary strata, in a more or less bigbi}' crystal- line condition, of an age between tbe two." Tbis referred to tbe Taconic system of Emmons, already at tbat time announced by bim as occupying an intermediate position between tbe I'rimary and tbe fossiliferous rocks of the New York series (§ 67). Logan, however, proposed on account of "tbe consid- erable dilHculties attending tbe question, * * * * to unite all tbe subjacent rocks, whether Metamorpbic or Primary, and to class them under tbe latter denomination." § 130. Mr. Murray, in bis re[»ort of progress for 1843, jiub- lisbed in tbe volume just mentioned, noticed tbat some of tbe Primary rocks on tbe northeast shore of Lake Huron, and far- ther eastward, north of Lake Simcoe, j (resent evidences of bedding or stratification, Avbich led him to "consider tbe term Metamorpbic as one of appropriate application to some of the rocks beneath the fossiliferous, and unconformable with them." He therefore designated this series (described by bim as simi- lar to those of tbe Thousand Islands) as "Primary and Meta niorphic nu^ks." § 131. In tbe year 1845, Mr. Logaii ascended the Ottawa river a distance of 150 miles from its mouth, to tbe bead of Lake Temiscaming, exploring, moreover, some of its tribu- taries, and caretully studied the geology of the region, niakiDg 5- -E. m 66 E. SPECIAL REPORT. T. STERRY HUNT, 1875. large collections. In the followiiis^^ year (18+0) he, with the aid of Mr. Murray, exiihtred in like manner the Canadian shores of Lake Superior. The lahors of these two yeare oon- trii)uted ^n'eatly to our knowledge of the older rocks, but the report.H of iheni were not published, nor indeed completed, un- til 1847. § 132. In this connection a personal statement may perhaps be permitted, as serving to give weight and authenticity to the earlier lithological and mineralogical descriptions in these, and in subs('f|uent reports of the Canada Survey, which have a his- torical importance in connection with the study of the older rocks. It was in February, 1847, that the present writer com- menced his lal)ors at Montreal, as chemist and mineralogist to the Geological Survey of Canada (after having previously, for some months, tilled the same post in the Geological Survey of Vermont, then in progress under Prof. C. B. Adams). The publication of the re])oriS of the Canada survey for 1845, hav- ing been delayed, he was thus enabled to examine and describe the various rocks and minerals frojn the region of the Ottawa, as well as those from Lake Superior. For the lithological and mineralogical notes and descriptions which occur in the reports for 1845 and 1840, and in the subsequent publications of the survey, during twenty-five years, the present writer is respon- sible, inas(nuch as they were all written by him or under his supervision. § 133. In Logan's report on the geology of the Ottawa, im\)- lished in 1847, the ancient crystalline rocks, which he had pre- viously called Primary, were distinguished, in accordance with Mr. Murray's previous suggestion, (§130) as "belonging' to the order which, in the nomenclature of Lyell, is called Meta- niorphic instead of Primary, and as possessing an aspect ind ucing a thecn'ctic belief that they may be ancient sedimentary foruia- tions in an altered condition.'' This "■ Metanior[)hic series" was then described as consisting of a lower and an upper group, the former consisting chiefly of reddish and grayish syenitic (that is hornblendic) gneisses, much contorted and generally at high angles. These were succeeded by a series in which, it was said, " im[>ortant beds of crystalline limestone become inter stratified with the syenitic gneiss, and their presence constitutes ROCKS OF THE UPPER OTTAWA, E. 67 i() Ro marked a eliaracter that it ai>i)ears exj»edient to coji.^iflerthe mass to which they hehmg as a separate group of metaniorplnc strata, supposed, from their geographieal position and general attitude, to overlie the previous roeks conformahly." § 134. A careful section of a portion of this " upper grou]>," as it was then called, was given, aceom[)anied by minute litho- logical descriptions of the gneisses of both groups, and of the crystalline limestones, together with the minerals botli of the strata and the numerous veinstones occurring in them ; — the results of a careful study by the present writer of the collec- tions made in !845. (Report for 1845, pp. 40-50.) In 1.^47 he spent some weeks in the field among the saine rocks, and his report thereon will be found to contain farther details ol' their mineralogy and lithology (Report for 1848, pp. 125-138). § '35. This Mctamorphic series, of two conformable groups, was described l)y Logan in 1845, as forming a great axis, cross- ing the Ottawa river, and separating the rocks of the southern trough of fossiliferous rocks, (the great Transition ti-ough of the St. Lawrence and the lower Ottawa, already noticed) from a northern trough, the strata of which was discovered by him on Lake Temiscaming, on the upper Ottawa, resting upon the Metamorphic series. They were then described as consisting, in ascending order, of l°,.chloritic slates and conglomerates; 2", greenish sandstones ; 3°, fossiliferous limestones. The first of these were grayish and greenish slates, chloritic or finely mica- ceous, often very compact, traversed l»y sean>s of quartz, and sometimes holding pebbles and rounded masses of the subjacent gneiss. These strata had a moderate diji, and an estimated thickness of not less than 1,000 feet. Reposing on these slates were Rcveral luuidred feet oi' greenish sandstones and conglom- erates, in neai'ly horizontal beds, overlaid by 400 or 500 feet of light gray limestones, sometimes abounding in chert and inter- stratified with gret'uish shales. Many of the limestones were very fossiliferous, containing the characteristic organic forms of the Niagara limestone. A conglomerate, made up of the ruins of the underlying sandstone, formed the base of the lime- stone series. § 136. In the following year (1846) the work of Logan and of Murray on Lake Superior and its tributaries, added much G8 E. SPKCIAL BEPOKT. T. STEKKV HUNT, 1875. more to our knowledijce of the older mcks. In liif^ roi)ort, pul)- lislied in 1847, tlie former described tlie Icnvest rock.s aUniL!; the north shore of the luke as consisting of granite and syenitic (hornblendicj granite, " which ai)pear to jtass gradually into gneiss." Siniihir rocks were also observed by Murray in the Kanianistiquia and Michipicoten rivers, liesting u[ion these ancient rocks, and in many places enclosing jiebbles of them, was u second series, described as consisting of chloritic, miea- ceons and talcose slates, sometimes epidotic, with interstratitied beds having the characters of greenstone, and others of ([U.irtz- rock, the whole series iinich contorted, and dijiping at high angles, with an oast and west strike. Tln'ir thickness was esti- mated at several thousand feet, and they were observed by Lo- gan at the moutb of the river Dore near (ires Cap, and at Tiiunder Bay, and also, by Murray, on the Kanianistiquia. The former declared that the "chloritic slates at the summit of the older rocks, upon which the Volcanic formations rest un- confomial)ly, strongly rcsend)le those of Lake Temiscaming, and it appears prol)able that they will be found to be identical" with ttiem. (Report for 1840, page 34.) § 137. The "Volcanic formations," above alluded to, are de- scribed by Logan, in the same report, as consisting of uncrystal- line sedimentary iitrata, interstratified with and overlaid by eruptive rocks, and were divided by him into a lower and upper group. The first of these was seen at Thunder Bay, resting, in a nearly horizontal jxisition, ujion the highly- inclined chloritic slates, fragments of which entered into a conglomerate at the base of the lower Volcanic series. Overlying this conglomerate were beds of chert orhornstone, with calcareous layers, sometimes becoming impure limestones; the whole, higher in the series, accom[)anied with dark bluish argillaceous slates and argillaceous sandstones, intersected by dykes, and interstratitied witii layers of crystalline hornblendic trap; a mass of which, 200 or 300 feet in thickness, caps the lower group, estimated to have a total volume of 1,500 or 2,000 feet. These rocks are seen at Thunder Bay and westward to Pigeon river, forming the shores of the lake and the adjacent islands. § 138. Resting upon this lower group to the eastward, was VOLCANIC fOKMATIo.NS OF LAKE Sl'l'KRIOK. E. GO a faeries of rod aiul vvliite siindstoiK's, iuid CDiigloineratos, lidld- ing jiebblcs of Jjisper, dieit mid liinesfone, and huviui; an esti- mated thickness of about 700 teot. These were succeeded \>y reddisli white conipaet limestones, interstratified with calcare- ous shales and sandstones, and overlaid by reddish marls, mak- ing, in all, about 130 feet additional. "Succeeding these cal- caremis strata, alter an interval of which the amount is uncer- tain,'' another series of red and white sandstones, with con- glomerate layers, was met with. These were interstratilied with layers of trap, often aniygdaloidal; "and an enormous amount of volcanic oveiHow crowjis the formation." Besides the bedded aniygorithyry. The thickness of this ui>i)er Volcanic group, on which were in- cluded the calcareous strataand the red and white sandstones be- neath them, was estimated, as seen in various sections, at from (3,000 to 10,000 feet. (Rei)ort for 184(3, pages 13-16). §139. This series was i'ound to the east of Thimder Bay, rest- ing upon the rocks of the lower Volcanic group just described, beyond which it was recou-nized on fSt. lijnace and the other is- lands along Nipigon Bay, and, liirther east, in Michiiiicoten Is- land, and on the maiidand at Cajic Gargantua, J'ointo aux Mines, Mamairlse and other places, in which the red sandstones, conglomerates and amygdaloids of the upper Volcanic group were seen to lie unconibrmably upon the ancient gneissic and granitic rocks. This sei'ies, in many }>arts of its distribution, abounds in native copper, and was by Jjogan regarded as iden- tical with that of Isle Koyale, then visited by him, and with the similar copper-bearing rocks of the southern shore of Lake Superior. As regards the age of tlie copper-bearing series, lie conceived it to be older than the horizontal j)aleozoic sandstones found in the vicinity of Sault Ste. Marie, and cited with ap- proval the opinion expressed by llaughton of Michigan, in 18-11, that it was probably more ancient than the Potsdam of the New York series. The important bearing of these facts on the history of the Lake Superior rocks will be apparent further on. las IMAGE EVALUATION TEST TARGET (MT-3) L<'- 1.0 m 1112,5 IM 12.2 I.I 2.0 1.25 1.8 LA. Illli:.6 yw/ ■m ^ V r c-i '^c^l -^ '^ (9^ 4 !> Photographic Sciences Corporation 23 WEST MAIN STREET WEBSTER, NY. 14580 (716) 872-4503 Ly arranged in stratified deposits, such astrap-tulf and i)eperino, which wore su})posed to bo largely represented in the copper-bearing for- mation of Lake Superior. rm 74 E. SPECIAL REPORT. T. STERRY HUNT, 1875. § 147. Includiuo; the specular and magnetic iron ores of Lake Superior (and of other regions) among the igneous rocks, the authors discuss the view tiiat they were deposited from water, which is declared to be inadmissible and inadequate to explain the geological relations of these ores. Nothwithstanding the banded structure of these deposits, as seen on Lake Superior, they were " disposed to regard the specular and magnetic oxyds of iron as a purely igneous product, in some cases poured out, but in other cases sublimed t'vom the interior of the earth." Many of the deposits of pure ore, enclosed in crystalline strata, or traversing such in dykes, are supposed to " have risen up in a plastic state from below ;" but when found impregnating crys- talline strata, or interlaminated with them, their introduction was regarded as due to sublimation. The banded structure of the masses of ore, and its iuterlamination with chert, jasper and other matters, suggesting aqueous deposition, they supposed to be due " to the action of segregating forces." (Geology of Lake Superior, II, 68.) § 148. The Azoic system, as defined by Foster and Whitney, included both the older gneissic or Metaniorphic series of the Canada survey (subsequently named Laurentian,)and the newer and unconformable crystalline aeries afterwards called IIu- ronian. This, as developed on the southern shore of Lake Su- perior, included besides chloritic and talcose schists, the great deposits of iron ores just referred to, masses of greenstone, to- getiier with dark colored compact serpentines, and quartzifer- ous porphyries ; all of which were regarded as being of igne- ous origin, and as intercalated in the metamorphic schists of the Azoic system. The copper-bearing series of tlie region, including the amyg- daloids, inter-bedded traps, and conglomerates, was however re- ferred to a more recent period, being regarded as forming a por- tion of the Totsdam siindstone. § 149. An instructive section given by Foster and Whitney (Vol. I, page OG) near the eastern end of Keweenaw Point, from Copper Harbor southward to Lake Labelle, traverses, in the northern portion, two principal ranges of bedded amygdaloid and granular trap with conglomerates and native cojtper. To the south of this, a third parallel cast and west belt of so-called JASPER AND QUARTZOSE PORPHYRY KoriCS. E. 75 ••iiii 'I trap, constitutes the Bohemian Mountains, descrihed as com- posed of " a vast crystalline mass, forming an anticlinal axis, flanked on the north hy the bedded traps and conglomerates, and on the south by sandstones with conglomerates " 'J'his southern range is said tube widely utdikeboth in structure and composition to the traps of the northern ranges, being a dark- colored tine-grained greenstone, made up of labradorite and green hornblende, sometimes with an admixture of chlorite. It is distinctly stratified, and di])s to the N. W. at an angle of 65° or 70°. At the southern base of the range is a broad belt of fissile chloritic rock, which is, in parts, an admixture of labradorite and felds})ar, with disseminated crystals of mag- netite and grains of copi)er-pyrites. § 150. Throughout this southern range native copper is want- ing, but numerous veins of quartz, sometimes with calcite and chlorite, are met with, carrying sulphurerted copjier ores. In the eastern part of the Bohemian range (according to Ri' ot) the greenstone is replaced by a jasper, which forms great masses, and makes the sunnnit of Mount Houghton. This rock is sup- posed by Foster and Whiniey to have resulted from the altera- tion, by the intrusive traj), of the adjacent sandstones, and is described as in some parts red, occasionally banded and com- pact, with a sub-conchoidal fracture ; elsewhere it includes feld- spar and chlorite, and shows lines of stratification. § 151. A similar red bandinl jasper-rock occurs in the Por- cupine Mountains, a range of hills near the southern shore of the lake, rising between Carp and Iron rivers, where a large area, designated in the geological map of Foster and Whitney, as composed of " igneous " rocks, is described by them as con- sisting of Jasper and quartzose porphyry. The highest parts of these hills are said to be composed of a compact red jasper, sometimes banded, and at other times mingled with grains of white quartz. It "sometinjes shows a gra(iual passage into quartzose porphyry, with occasional imbedded crystals of felds- par." Such a porphyry forms very large masses on the head- waters of Iron river, where it is brick-red in color, and con- tains small crystals of white feldspar, generally with " rounded grains of vitreous qiuxrtz found distril)uted with the feldspar through the jasper base." Other varieties are described with 76 E. SPECIAL REPORT. T. STERRY HUNT, 1875. i I I !! rod feldspar crystals. This rock was regarded by the authors as an eruptive mass, and said to include fragments of older rocks. (Geology of Lake Superior, I, 65-70). The banded structure of some of the jasper of Mount Houghton was re- garded bv them as due to the original stratification of the sedi- mentary deposits, while that of the banded jaspci if the Por- cupine Mountains was declared (Ibid. II, 68) to present com- plex flexures, which " bear no mark of having been the re- sult of original stratification ;" there being no actual line of separation between the lighter and darker bands. We shall again refer to these jaspers and porphyries. § 152. In 1854, and again in 1855, Prof. Rivot, of the Ecole des Mines of Paris, visited the mining-region of Lake Su- perior, and described his observations in two elaborate memoirs in the Annales des Mines for 1855 and 1856 (5me. serie, vols. V and X). We have already made use of his statements in speaking of the Bohemian Moun+ains. Rivot recognized in this region, besides the ancient granitic and syenitic rocks, which he regai'ded as eruptive, a vast series of chloritic and hornblendic schistose rocks, which, according to him, pass by insensible gradations into the massive greenstones found inter- stratified with them. Hence he rejected entirely the notion of the igneous origin of the greenstones, described by him as consisting chiefly of labradorite and hornblende, which were conspicuous in the hills of the Bohemian range already no- ticed, as well as in the Huron Mountains and near Marquette. The cupriferous aiuygdaloids and bedded traps of the more northern ranges in the Keweenaw peninsula were supposed by Rivot to belong to the same series as the greenstones found with the chloritic and hornblendic schists mentioned above, and to pass into them by gradations. § 153. Rivot thus rejected entirely the notion of the erup- tive or volcanic origin of the amygdaloids and bedded trai>s of the cupriferous formation, maintaining that they were of meta- morphic origin, and in fact that these, as well as the whole se- ries ot greenstones with chloritic and hornblendic slates, ser- pentines, jaspers and iron ores, in the Huron and Bohemian Mountains, had resulted from the more or less complete altera- tion of ferruginous slates and and sandstones "by some un- RIVOT ON LAKE SUPERIOR. E. 77 nul vo. known agent." The whole of these strata were by him sup- posed to be intercalated in the lower part of the paleozoic se- ries, and he did not apparently recognize any disi-ordance ot stratification between the ])receding rocks and the superioi sandstones of the region, lie noticed that in the greenstone and chloritic series of the Bohemian range (and elsewhere) cop- per was found in veins, in the form of sulpiiuretted ores, but ho believed that these veins were in some cases continuous with those which, in the amygdaloid belts to the northward, carried metallic copper. § 154. llivot was familiar with the results of the Canadian survey, and in his memoir of 1856 gave an analysis of the Esquisse Geolo()i(]ue, already mentioned, citing the names Lau- rent ian and lluronian. lie there states more distinctly than in his first memoir his view of the relations of the various rocks, and declares that "in immediate contact, and apparently with the granite, are found rocks evidently raetamorphic, mica- schists, hornblendic sc-hists very analogous to traps, <^uartzites and jas^ters. At a certain distance, and above these, are the) traps, conglomerates and sandstones, the stratified arrangement of which is very evident. It is not possible, at least on the American shore, to separate the traps from the other Silurian i \ rocks." On the other hand, he describes traps as passing into well characterized raetamorphic schists, and declares them to be "so connected with the metamorphic rocks, referred by Mr. Logan to the Cambrian (lluronian), that it is not possible to separate the two. These appear as the last term of the meta- morphic action manifested at the contact of the granite, of which action the granite itself may perhaps represent only the highest development." The discordance noticed by Logan at Thunder Ba}' between the crystalline schists and the overlying series of argillites and sandstones with traps, Rivot thought might only be a local phenomenon, "to be explained by move- ments due to the neighberhood of the granite." § 155. The granites of this author were the granitoid rocks of the Laurentian system, which he elsewhere described as "important masses of granite, syenite and diorite, which seem to have traversed and disturbed" the more schistose lelds[)athic, micaceous and hornblendic rocks, and the crystalline limestones m I I i 1 I 78 E. SPECIAL REPORT. T. 8TERRY HUNT, 1875. of the Laiirentian. In the bedded trappean rocks of the cop- per bearing series he, however, failed to recognize any eru]*- tive masses, and found none of "the dykes of trap or diorite" noticed by Logan in this series on the north shore of tlie lake. The granites and related rocks seem to have been the only masses in the region to which Rivot assigned a phitonic origin. § 156. The observation of Rivot regarding the origin of the beds of rounded pebbles found between ridges of trap at Ke- weenaw Point deserves notice in this connection. They were, according to him, "due to the decomposition, by atmospheric agents, of the ancient conglomerate." The present writer, from his observations on the north shore of the lake in 1872, arrived at the same conclusion. At Mamainse, interstratified with the traps, are beds of conglomerate made up of large and small rounded masses of granite, red and gray Laurentian gneiss, chloritic schists and greenstones from the Iluroniaii series, and tender mica-schists and gneisses having all the characters of the Montalban, together with masses of red quartzose sand- stone, the whole cemented by white cleavable calcareous spar. The solution of this has reduced large portions of the con- glomerate to loose pebbles, which form the lake shore. § 157. It thus appears that Rivot, while adopting, with re- gard to these rocks, a view the very opposite of that main- tained by Logan, Foster and Whitney, and Dawson, — inasmuch as he denied the eruptive origin alike of many of the crystiil- line greenstones of one series and of the bedded granular traps and aniygdaloids of the other, — was led to agree with Logan, and with Dawson, in assigning the two series to one geological horizon, and in regarding their mineralogical and lithological dif- ferences as due to variations in the degree of alteration. This extreme extension of the doctrine of metamorphism, which began to find favor with other geologists about the same time, was the natural reaction from the no less extreme plutonism which had hitherto prevailed, and marked the beginning of a revolution in geological theory. § 158. In 1857, Prof. J. D. Whitney published in the Ameri- can Journal of Science ([2] XXIII, pp. 305-314) a review and criticism of the Laurentian and Huronian systems of the Canada geological survey. lie therein asserted that "there is WHITNEY ON LAKE SUPKItlOR. E. Id no evidence, either litliological or stratigrapliical, for separat- ing the rocks of Lake Huron from those which occur farther east, and wliicli are classed by Mr. Logan as Laurentian." Both of these, Whitney had inchided in his Azoic series, which lie declared to consist, alike on the north and south shores of Lake Superior, ''of talcose and hornblendic slates, and gneisa- oidal quartz-rock, resting on a granitic and syenitic nucleus." § 159. As regards the cupriferous series of the north shore of lake Superior, — the upper division of the Volcanic forma- tions of Logan, — he confirmed the opinion of the latter, that it was identical with that of the south shore. He had himself examined the truppean series in Ni{)igon Bay and the island of St. Iguace, and found its geological structure identical with that of Isle Koyalc and Keweenaw Point. (Geol. Lake Su- perior, II, 115.) The dark-colored argillites, cherts and sand- stones of Thunder Bay, which Logan made the lower division of his Volcanic formations, represent, according to Whitney, only "a IocpI variation in the composition," analogous to "the dark-colored and highly fissile beds of the Montreal, Presque Isle and Iron rivers of the south shore, which pass gradually into the usual red sandstone upwards and downwirds." P'rom the examination of this series, as developed in the south shore, he was "unable to see any reason for separating the cupriferous range from the sandstone which flanks it on either side." § 160. Whitney farther declared that " the native-copper bearing series of the north and south shores of Lake Superior cannot be separated from the Potsdam sandstone with which it is associated ; neither is there any reason whatever for placing it in the same line with the rocks of the north shore of Lake Huron. These latter, as well as the great mass of crystalline rocks to the north and east, in Canada, are identical in position and lithological character with the series described by Mr. Fos- ter and myself under the name of the Azoic system, and which cover so large an extent of territory in Michigan, Wisconsin and Minnesota." The rocks of this system, according to Whit- ney, underlie directly the trappean copper-bearing series, alike on the north and south shores Ox Lake Superior. § 161. The reasons of these opinions were given at length in the paper quoted, and need not bo discussed here. The ver- m ii' 80 K .SPECIAL REPORT. T. STERRY HUNT, 1875. V diet of later investigationa has confirmed the previous deter- minations of tlie Canadian Burvcy, botli as to the existence ot two distinct and unconformable series in the Azoic system of Whitney, and the unconformable infra position of tlie trapjican copper-bearing series to the so-called Potsdam sa Istone of the region. In his other principal point, however; namely, his objection to Logan's early attempt to establish a [larallelism between the upper crystalline schists of Lake Huron and the trappean or Volcanic copi»er-bearing series of the north shore of liake Su- l)erior, Whitney has bet-n fully justitiod. Jle pointed out that ,the latter had t)een declared l)y Logan to rest unconfurmably, /in Thunder P>ay, on a formation of crystalline schists, and ' these, according to Whitney, were the precise equivalents of those of Lake Huron, — which had been by Logan compared with the overlying trappean series. There was, in fact, no gf)od reason for this view of Logan's, — in which, however, he had, as we have soim, been followed both by Kivot and by Dawson, — and in the latter publications of the geological survey of Can- . nda, the trappean series was, in accordance with the view of Whitney, separated from the lluronian, but, at the same time, from the overlying sandstones. § 1G2. In the years following 1849 no further attention was given by the Canadian survey to these rocks on Lake Huron or Lake Superior, until in 1854-1858, when Mr. Ahirray made his e2:tended and careful geological and topographical surveys of the northeastern tributaries of Lake Huron and the region eastward. These explorations furnished many details of the Laurentian and Huronian series, the results of which are set forth in the annual rejiorts for the years mentioned. From 1858 to 18G8 no aimual reports were published by the Canadian survey, but the results of explorations during this time were embodied in the volume of the Geology of Canada, published in 18(53 ; in the Atlas and its accompanying text, which appeared in 1865; and in the larger geological map, (§44) published in 1866. In all of these the name of Huronian was restricted to the upper crystalline series of Lake Huron and the similar rocks on Lake Superior, where their distribution had been care- fully studied by Mr. Murray in the years 1859 and 1860. MURRAY ON LAKE SUPERIOR. E. 81 his of rdance with the views of Mather, (§ 80-81,) whose Report on the South- ern district of New York was at tliat time carefully studied by tlie Canadian Survey, as having resulted from the alteration ot' the strata of the Hudson River group, which were supposed, at certain points along the line of contact between the two, to exhibit evidences of a gradual passage from the uncrystalline sediments to the crystalliae schists, in summing up the facts detailed in elucidation of the structure of the Notre Dame range, designated as " the Green Mountains in their Canadian prolongation," the conclusion was reached that " the whole of the Green Mountain rocks, including those containing the au- riferous quartz veins, belong to the Hudson River group, with the possible addition of part of the Shawangunk conglomer ates." (Ibid, page 57.) § 174. The section along the St. Francis was continued from Sherl.rooke southeastwards across the limestones of the valley, and thence to Canaan, in the northeastern corner of Vermont. The rocks were described as soft argillaceous, micaceous and calcareous schists, highly pyrititerous, succeeded by harder mi- caceous and quartzose strata, often with garnets and chiasto- lite, associated with beds containing black hornblende, and with granites. The latter were regarded as intrusive, which is true uf a portion of the granitic rocks of the region. These strata were found to be highly inclined, with a prevailing in- clination to the north-west, the latter ]iart of the section form- ing a bold range of hills, in which the Connecticut and Chau- diere rivers take their rise. No detailed examination was made of that part of the line of section from the limestones of the valley of Lake Massawippi to Canaan ; the description of it given in the Report for 1847 having been taken from the notes made by Logan during a journey across the region aa early as 1842. He however ventured, in accordance with the will GEOLOGY OF EASTERN CANADA. E. 87 views which had been advanced by Mather and the Messre. Rog- ers, (§ 123) to assign these rocks to a higher geok^gical horizon than the Green Mountains, and while the whole of the inter- vening calcareous strata were supposed to be Silurian, to put forth the siitrgestion that the mica-slates, with hornblendic, gneissic and granitic rocks, were perhaps of Devonian age, being "a part of the Gasp6 sandstones in an altered state." (Report of 1847, pages 55-58). § 175. During the year 1849, the investigation of the Notre Dame range, and of the disturbed sedimentary belt along its western and northern boundary was continued, the latter being examined at various points from the northern extremity of Lake Champlain as far as tlie vicinity of Quebec, and thence along the nortliern shore of the 8t. Lawrence for about 130 miles, to the Temiscouata portage, a road leading to the lake of that name. The results of these investiirations are set forth in the R«port for 1849, publislied in 1850 (pages 31-64). Jjogan was aided in this field-work by Murray, and by the present writer. (Ibid, pages 6, 73.) In describing the general distribution of the rocks along the south shore of the St. Lawrence, we have already made use of this exploration, and also of that of 1844. In this latter re- port Logan had given (pages 17-30) the results of his exami- nation of this coast from Capo Chatte, a point a little farther east, to Cape Rosier at the extremity of the peninsula of Gaspe, and had also described the newer limestone and sand- stone-formations lying to the southward, (§ 168) which were then designated the Gaspe limestones and the Gaspe sandstones (pages 31-66). § 176. The opinion was expressed in 1844, that these coastal rocks, or at least a portion of them, are '' the equivalent of a part of the Hudson River group of the Xew York geologists" (page 21). It was aiterwards elearly apparent that they were similar to those found along the ooast between the Temiscouata road and Quebec, and to the belt now traced from Quebec to Lake Chamjilain. These, as we have seen in the Report for 1847, were also referred to the Hudson River ir roup, rcirarded as bo- longing to the upper part of the C!hamplain division of tho ^ow York series, and m the same Report (page 58) reference !!;■ ! |i. 88 E. SPECIAL REPORT. T. STERRY UlTNT, 1875. was made to " the continuous run of the reco2:nizcd rocks of the Hudson River group from Lake Chanipluin, along the south side of the St. Lawrence, to Cape Rosier." In the Rei)ort for 1849 (page 18) it was again mentioned that " a formation con- temporaneous with the Hudson River group, superior to the Trenton limestone, extends along the south side of the St. Law- rence from Point Levis (opposite Quebec) to (Jape Rosier." The continuity of this belt of sedimentary rocks, along the east side of Lake Chaniplaiu, with the similar rocks to the east of the Hudson — the Argillite and Graywacke series of Eaton — bad already been established by Emmons and by Ma 'her, as shown in the preceding chapter. § 177. The observations of Mather and Emmons as to the singularly disturbed and often inverted attitude of these strata in the regions just mentioned were abundauiiy confirmed by the oflicers of the geological survey of Canada. The belt be- tween Lake Chaniplaiu and the Tennscouata road is described as presenting "a multitude of anticlinal axes, over which, in succession, the strata bend in sharp plications, often leaning over to the northwest, giving the semblance of a nearly con- stant dip to the south-east, at high angles. These folds are so numerous, and frequently repeat the measures several times in so short a distance, as to destroy confidence in every endeavor to estimate the thickness of the different divisions of the de- posit ; and the want of knowledge of the true tliickness, on the other hand, renders it uncertain, in any particular case un- der examination, whether all the folds afiecting a set of strata have been correctly ascertained. The main undulations can of- ten be followed for considerable distances by means of the geo- graphical distribution of contorted masses of the sub divisions, but unless a connection or relation with regard to each other is followed out among these undulations, it is somewhat difli- cult to determine whether a form that may be subject to con- sideration is synclinal or anticlinal." (Report for 1849, pp. 31-8±) § 178. An illustration of this inversion of strata is seen in the Report for 1847 (page 24), where, in Granby, not far to the north of Lake Champlain, the red and green sandstones of the series in question are said to be folded in a great overturned INVERBIONS OF STRATA. E. 89 Byuclinal, in which the strata, on both sides of the basin, dip to the Boutheast at angles varying Iroai 45° to 80°. Still more remarkable examples of this are shown in the Kcport for 1844, in the account of the same belt ou the south shoio below Quebec, where it is said that the rocks "as they come out on the .St. Lawrence exhibit a very contorted con- dition. The tlexures are numerous, and some of them are so violent that serious inversions of the strata sometimes present themselves, and it is frequently very difficult to determine whether the mass under inspection be a new member of the de- posit, or a repetition of one previously noted." (Keport for 1844, page 18.) § 179. Numerous examples of this are given, one of which is on the east side of the lliviere I'ierre, where the summit of the hill sliows an overturn d\\), and the strata in the whole sec- tion appear to be arranged in the ibrm of a very flat S' Farther down on the coast * * * there are evidences of an over- turn dip, * * * and a little under two leagues above Capo Magdalen, and about the same distance from Gros Male, the apex of the flexure connected with it comes out upon the shore. The direction of the anticlinal axis appears to be N. 65° W., magnetic, and proceeding from it upwards along tlie beach the strata, presenting at first a north dip of 20° to 40°, gradually bcoome vertical ; further on they overhang ; still further the overturn increases, and the beds, becoming flat, with the bottom upwards, in this inverted position, roll farther over, and for a short distance slope slightly northward. From tliis, however, they recover, after no great interval, but tiually in Gros Mille bluff, they exhibit a short twist, occupying about twenty feet in the upper part of the cliff, in which, after re- turning to an uninverted north dip, they are again canted over to a nearly horizontal position, with tiie bottom upwards. Tlio inverted beds examined extend upwards of five miles along the shore, and though the twists in the north side of the anti- clinal, which roll them over to an upside-down north dip, are short, and therefore do not produce so imjiortant a result as the simple overturn south dip, they serve to illustrate the comjilica- tion of the strata, and the difficulty of disentangling them in pi' hi I.,: I 90 E. SPECIAL REPORT. T. 8TERRY HUNT, 1875. I|:l endeavoring to follow out the order of superposition." (Ibid, pp. 23-24.) § 180. The strata in this disturbed region, below Cape Chatte, were described as consisting of great masses of sandstone, the vertical beds of which, by the action of the sea-waves, are wrought into upright columns, known to the navigators as Pil- lars, for which reas^on these rocks were called, in the Report, the Pillar sandstones. These sandstones, which are greenish in color and often conglomerates, holding pebbles of quartz and others of black shale, were found to be associated with bands of red, and more rarely with black argillaceous slates. A nother portion of the series consisted of gray calcareous sandstones and gray limestones, sometimes oolitic in structure, together with conglomerates composed chieily of limestone pebbles, in- terstratitied with green and black argillites. Other portions presented thin-bedded limestones with gray sandstones and black shales holding graptolites. § 181. In the Heport for 1819 an attempt was made to estab- lish the succession of these rocks "in ascending sequence from the Trenton limestone and Utica slate.'' They were then di- vided into live groups, as follows: 1. Dark gray clay-slates, with gray thin-bedded sandstones, often calcareous, and with gray limestones, both weathering yel- lowish-brown. This division holds shells and graptolites, and appears to be terminated by bituminous shales and black lime- stones. 2. Gray, green and red shales, with thin calcareous layers and bands of calcareous conglomerate. 3. llard gray sandstones, rarely greenish, frequently becom- ing conglomerate from pebbles "of gray limestone containing organic remains of the Trenton formation,'' besides thin-bed- ded gray limestones. 4. Red and green and chocolate-colored shales, often inter- stratifiod with thin bands of light gray sandstone, which is sometimes calcareous. 5. (Joarse -grained, green, massive sandstones, holding scales of mica and grajthite. "They appear to derive their prevailing color from chlorite, but rod layers, as coai-se as the green, and holding nearly as much chlorite, are in some parts interstrati- CHLORITIC SANDSTONES OF QRANDY. E. 91 Hi- es If lied." These rocks are often coarsely conglomerate, with quartz pebbles, "which sometimes ap[)ear to become mingled witli peb- bles and even boulders of gray limestone, holding fossils proba- bly of the Trenton formation." lied and green slates are in- terstratified with this division. § 182. This succession, the description of which is abridged from tliat given in the Report of 1849, was determined almost wholly from the section seen near Quebec, on the island of Or- leans and at Point Levis, although details of some of the di- visions were iiathcred from other localities. The rey-ion farther eastward was, as already shown, too much disturbed to give any satisfactory evidence as to the sequence, while to the south- west the strata are concealed, for long intervals, by the great mass of superficial deposits, and but few outcrops, and these of small portions of the series, are met with. Thus, the fossili- ferous limestones are known to the southwest of Toint Levis within the limits of the province, only at and near Phillipsburg on Lake Champlain. The green sandstones of the scries are not met with in this vicinity, but are seen a little to the north- ward, in Milton, Roxton and Granby, and at various points from the 8t. Francis river to tlie vicinity of Quebec, beyond which they are larj.'ely displayed in the region to the northeast* § 183. The presence of chlorite in these sandstones was no- ticed at several localities below Quebec in the interval between the crystalline rocks of the Notre Dame and the Shickshock Mountains, (Report ot 1849, page 47) and also in Granby (Re- port of 1847, [lage 25). Here the green sandstones, with some red beds, are occasionally calcareous, and often conglomerate, holding pebbles both of quartz and of feldspar, together with scales of mica and of graphite, and constituting an arkose. The grapiiite, and the chlorite to which they owe their color, are more abundant in the finer than in the coarser l)eds. Inter- stratified with these sandstones, and with red and green slates, some of which also abound in scales of mica and of chlorite, are two calcareous layers, one and two feet in thickness, earthy in texture, and weather ,ng brownish from the presence of man- ganese, but witiiin of a green color, evidently due to a large admixture of chlorite, (as was shown by a jiartial analysis at the time,) and containing a small proportion of oxyd of chromium. I lu r I i t- 1 '■ hIi wnr 92 E SPECIAL REPORT. T. 3TERRY HUNT, 1875. t: ^ A careful study of this locality waia BubHequently made by the writer, and the results of a chemical unalytiis are given in the Report for 1853-5G (page 474). The green earthy mass held inibedded scales of chlorite, and yielded to dilute acids about 30.0 per cent of carbonate ol lime, besides small portions of magnesia, manganese, iron and alumina. The residue con- tained no lime, but gave of silica, 53.20 ; alumina, 7.90 ; pro- toxyd ot iron, 15.75; magnesia, 8.79 ; titanic acid, 0.30 ; oxyds of manganese, chromium, nickel, ami loss, 2.00 ; alkalies, 0.00 ; volatile, 4.80=100.00. The oxyd of chromium was found equal to 0.30, and that of nickel to 0.15 per cent. ^ 184. The presence of these chemical elements, and of the dis- seminated chlorite, wiiicli evidently forms a cojisiderable pro- portion of the matter analysed, were, at the time, considered as evidences of a commencement of metamorphism in the sedi- mentary strata, and as marking the passage of these into the crystalline rocks of the Notre Dame range, which, in accordance with the view then held by most American geologists (as set forth in the preceding chapter), were supposed to be no other than these same strata in a highly altered condition and, in the imme- diate vicinity of Grauby, abound in chloritic schists, and in titan- iferous iron ores, with manganese, chrome and nickel. The more sim[)le and obvious view that these matters, like the quartz, feldspar, graphite and mica of the arkose, had come from the disintegration of the adjacent crystalline formation was then rejected by the writer, as being incompatible with the notion of the contemporaneous origin of the two series of crys- talline and uncrystalline rocks, which was at that time unques- tioned, except by Emmons. This geologist, as we have seen (§ 05, 107), had already noticed the existence of chlorite in these sandstones in Vermont and in New York, but main- tained that it was derived from the ''chloritic slate alonsi the eastern border," and also suggested the presence in these sand- stones of the "debris of hornblende." § 185. These sandstones, where they appear on the St. Fran- cis river, arc traversed by dykes of greenstone, and about two miles below, in Wendover, is a great development of green- stone, sometimes porj)hyritic, and at other times amygdaloidal, with agates and calcite. These masses are apparently conform- GREENSTONES AND COPPERBEARINQ STRATA. E. 93 an- le •iin- wo ■en- liil, I'lU- uble to the stratitication, and are associated witli graptolitic shales, into which the aniVL''daloid seems to •graduate. tSuine of the beds are apparently a breccia, made up of Iragnients of the porphyritic greenstone, cemented by calcite (Geology of Can- ada, 1803, pages 243, 710). The greenstones are traversed by brccciated veins carrying sulpliuretted ores of c()i)per. Simi- lar greenstones and amygdaloidsarei'ound fartlier northeast in the same strike, at St. Flavien, interstratiiied with red slates and calcareous conglomerates. Here also, sulphuretted copper ores are found both in the strata and in transverse veins, in ad- dition to which native copper occurs witii calcareous spar in druses in the conglomerate. " The whole band has a striking resemblance to some of the rocks of the Upper Copper-bearing series of Lake Superior." (Ibid, pages 242, 720.) § 18G. In the extension of this belt to the southwest of the St. Francis large beds of magnesiun limestone are found, asso- ciated with dark gray slates, and abounding in a fueoid resem- bling Buthotrephis Jiexuosa of Emmons. These are accompanied with great interbedded masses of greenstone, like those of Wendover and St. Fiavien, while the limestones contain, in nu- merous localities, sulphuretted copper ores, as in Wickham, Durham, Upton and at Actouvale, where a mine was formerly wrought from which rich ores, yielding over 1,0U0 tons of cop- per, were extracted. These ores were chietiy found in a lime- stone-conglomerate, occasionally presenting the aspect of a brec- cia, the fissures of which were filled with variegated ore, calcite and quartz ; and at other times forming a compact mass, in which rounded and angular fragments of limestone, and others of chert, were enclosed in a paste of vitreous and variegated sulphurets of copper, which are seen in polished sections to present a banded or stratified arrangement. The conditions at Upton, where copper-py rites occurs, are very similar. (Geology of Cana- ada, 18G3, pages 241-244; 712-720.) § 187. The greenstones of Actonvale and Upton were exam- ined chemically by the present writer, and found to consist of a basic feldspar, sometimes clcavable, with hornblende or pyr- oxene, and an amorphous green hydrated silicate related to chlorite. They were shown to resemble closely in composition f\ 94 E. SPECIAL REPORT. T. STEKRY HUNT, 1875. II ::i! the greenstones described by Wliitncy from tlic Upper Cop[ter- beariiii^ rocks of LuKe Supori(jr. (Ibid, {)uge 004.) § 188. Tills remurkablo dovelopineiit of cop{>or ores along a portion of the belt does not seem to be dependent upon the presence of the greenstones, since the ores appear in the Tune- stones in Wickhamand Durham, near Actonvale, where the greenstones are unknown. This, moreover, is the case at St. Henri and Point Ijcvis, near Quebec, in both of which places the red slates of the series contain jilatcs and masses of native copper, sometimes of several pv^unds weight, it is j)robably however to the presence of these hard greenstone rocks that are due many outcrops of the soiter copper-bearing limestones, which elsewhere are worn down and concealed beneath the su- perficial deposits. § 189. We have now to inquire into the reasons which led tlie geological survey of Canada to assign the sedimentary rocks on the south side of the St. Lawrence to the upper part of the Chami)lain division of the New York series. These reasons may be considered under two heads. In the lirst place is to be mentioned the continuity and identity of this series with the Argillite and Graywacke series iu western Vermont and eastern New York, which had been referred by Mather to the Hudson River group, (considered to bethestratigraphical equivalent of ihe Loraiue shales) and the Oneida or iSiiawaugunk formation. (§ 71, 72, 73.) To this was to be added the clearly expressed opinion of Emmons, iu 1842, that the green sand- stones examined by him at Quebec were to be assigned to the last named formation. (§ 05, 112.) § 190. In the second place were to be considered the facts ob- served in the vicinity of Quebec, where u nearly complete sec- tion of the series is to be seen in close proximity to the Tren ton limestone. In a geological account of this region by Dr. J. J. Digsby, published as early as 1827, (Proc. Geol. Soc. I, 37,) he described the fossiliferous limestone resting in a nearly horizontal attitude upon the ancient gneiss on the northwest side of the St. Lawrence, at Deauport, while the heights on both sides, including the city of Quebec, Point Levis, and the island of Orleans, were said to consist of " a slaty series of shales and gray wacke," occasionally passing into a brown lime QRAYWACKE 8EKIE8 OF QUEBEC. E. 9.'. stoue, antl altomatinu; with a calcareous cotiujlomerato in beds, Bonie of tliem charged with torisils, which, according to him, were derived from the horizontal liuK'stone of Beau{)ort. From this he concluded that the Graywacke series, which is highly inclined, is more recent than the liniestones. These he sup- posed might belong to the carboniferous jKjriod, to which also he referred the (iraywaclce series. This contains small veins of a bituminous matter, regarded by him as coal, and what he supposed to be vegetable impressions, called by him fucoids, under which name two species from this locality were described by Ad. Brongniart in 1828, as pointed out by Prof. James Hall, who, nearly thirty years later, describtd and figured these im- pressions as new forms of graptolites. Geol. Sur. of Canada, Decade II, page 60, and Report for 1857, page 111.) § 191. Bigsby 's view of the greater antiquity of the Beauport limestones was, as we have seen, adopted as probable by Logan, (§ 128) and was conlirmed by Admiral Baytield, who in 1845 (Geol. Journal, 1, 455) expressed the opinion that the Hat lime- stones of Beauport and of Montmorenci pass beneath the Gray wacke series. Ue, however, was aware that these limestones, which had been traced, at intervals, along the north side of the ISt. Lawrence to Montreal, belong to the Trenton formation of the Champlain division, and hence referred the Graywacke series, which was still supposed to hold in its conglomerates fossils derived irom this limestone, to the higher members of that division. The presence in the shales of the Graywacke series in Gaspe, of graptolites, which were supposed to be- long to the Utica slates, served to conlirm the conclusion that the position of this series had been correctly determined. The graptolites of Point Levis were not re discovered until 1854, but this locality had, as early as 1848, yielded to Logan two brachiopodous shells, mentioned by him as " a Lcpfnena very like L. sericea, and an Orthis very like 0. testudinaria, and taken by me to be these species," which are characteristic of the upper part of the Champlain division. (Amer. Jour. Science, [2] XXXIII, 106.) § 192. It is to be noticed that a few miles to the northeast of Quebec, rocks undoubtedly of the age of the Utica and Lo- raiue formations overlie conformably the Trenton limestone, II iH is '4 96 E. Lilil SPECIAL REPORT. T. STERRY HUNT, 1875. as is seen on the Moiitmorenci river, and beyond, along the left bank of the St. Lawrence; and also tliat a few miles to the southwest of Quebec, strata of these same two forma- tions, occupying similar stratigraphical relations, appear on both sides of the St. Lawrence, and are thence traced con- tinuously to the valley of Lake Chami>lain. These, moreover, oiler such lithological resemblances to the Gray wacke series of Quebec and Point Levis, (which, as has been shown, extends for hundreds of miles to the northeastward, along the right bank of the St. Lawrence,) that the two series of rocks were readily confounded, and thus the whole of the belt of sedimentary strata along the southeast side of the St. Lawrence, from the valley of Lake C'hami)lain to Gaspe, came to be regarded as younger than the limestones of the Trenton group. (Hunt, Chem. and Geol. Essays, page 395.) § 193. The Trenton limestoiie, along the left bank of the St. Lawrence near Quebec, is in many places almost horizontal, but is affected by occasional anticlinals running north-east and south-west, having the stee}tor dips on the south-east side. These, in some cases, pass into considerable faults or disloca- tions, with downthrows to the southeast. One of them is traced along the southeast side of the road from 13eau])ort church to the River Montmorenci, where the disj)lacement gives rise to the well-known water-fall of about 250 feet. The Trenton limestone, lying nearly flat at the top, is seen at the foot of tlie cascade, resting, with its edges upturned, at an angle of 57° against the gneiss, and dip})ing to the southeast beneath a conformable succession of beds of the Uticaand Loraine shales, which extend to the shore of the St. Lawrence. Other and similar dislocations, nearly parallel with this, occur on the northeast bank of the St. Lawrence above and below Quebec, examples of which are seen at Pointe aux Trembles and at Stc. Anne de Beaupr6, in which the Utica, in the one case, and the Loraine in the other, are found leaning, with a high southeast dij), against the gneiss. (lie[)ort for 1852, pages 28-40). § 194. At a distance of about eight thousand feet across the line of strike from the Heuuport and Montmorenci dislocation, against which the Trenton, Utica and Loraine strata arc mnde to dip southeast at a high angle, we find rising from the low QRAYWACKE SERIES OF QUEHEC. E. 97 57° Ith a iind the ibec, Sto. the I cast lline tion, liiide low lands behind the city, and from tlie waters of the St. Lawrence, the Graywacke series which forms the heights of Qnebec, Sil- lery, Cape Rouge, and Point Levis, and the island of Orleans. These strata, near Cape Rouge, dip S. 25° E.,and on tlie island of Orleans, S. E., in both cases at an angle of al)out 50°, and though affected by many minor undulations, have a prevailing high inclination to the southeast. The thickness of the se- lies here displayed, as measured by Logan, was estimated at over 5,000 feet, and the sequence is essentially that previously described, (§ 181). § 195. In 1855 was published the Esquisse Geologiquc, al- ready noticed, (§ 144,) in which (page 80) the rocks of the southeast side of the St. Lawrence weredescribed as forming part of a great paleozoic area, including also the Kew England states, together with Ontario, New York, and the whole of the paleozoic rocks to the south and west. This vast region was, according to Logan, divided into two parts by an anticlinal axis, which, following the Hudson river and passing to the east of Lake Champlain and the Richelieu river, reaches the St. Lawrence at Ueschambault, about twenty-five miles above Quebec. The region to the west of this, designated by him the western basin, includes the comparatively undisturbed strata of Ontario and New York, and the Appalachian and Michigan coal-fields ; while to the east jf this axis are found the disturbed and, in part, crystalline rocks already described, which surround tiie coal-tields of New Brunswick and Riiode Island. Thisattemj»ted generalization, it will be seen, was but a repetition of that already luade l)y Mather, who, in 1843 had already traced this supitosed axis from New Jersey nearly to Lake Champlain, and had asserted that the rocks on the east side of it are nothing more than the disturbed and modified equivalents of those on the west (§ G9, 72, 81). § 196. This anticlinal, in its course through eastern (\anada, was declared to Dring to the surface the Trenton limestone and "the lower part of the Hudson river or Loraino shales," rest- ing upon which were the rocks of Quebec, Orleans and Point Levis — now first designated the Quebec formation — overlaid by the red and green shales and the green sandstones of di- vision 5, (§ 181) which, from their occurrence at Sil 7— E. ^11 it I' -I . I 98 E. SPECIAL REPORT. T. STERRY HUNT, 1875. lery, were designated the Sillery formation, and declared to correspond to the Oneida or Shawangunk of Xew York. In the geological map published with the Esquisse, these Quebec and tiillery formations were represented, respectively, as the equivalents of the Hudson River group and the Otieida forma- tion, and in accordance with the views of Mather, the crystalline rocks of the Notre Dame Moutains were regarded as the al- tered equivalents ot these (Esquisse, pages 40-60). § 197. Thegraptolites of Point Levis were first described by Prof. James Hall in 1855 (Report for 1857, page 109). They were unlike those hitherto known in the Utica slates of the Champlain division, and were regarded as belonging to a higher horizon — according to Prof James liall, "■ that part of the Hudson River group, which is sometimes designated aa Eaton's Sparry limestone (§ 52), — being near the summit of the group." (Ibid, page 117). § 198. These rocks had been carefully traced by Logan from Canada into Vermont, and Ibund to include the Red sandrock of that region, which Adams, in 184(3, and W. 13. Rogers, in 1851, had already, in opposition to the views of Emmons, as- signed to the summit of the Champlain division (§ IIG, 117, 118). The slates associated with the Red sandrock at Georgia in Vermont subsequently yielded two species of trilobites, which were described by Prof. James Hall, in 1859, in the 12th Reports of the Regents of the University of New York, as belonging to the genus Olenus. These remains, subsequently referred by him to a new genus, named Olencllas, were in 1800 described by Emmons as species of I'aradozides. That these trik)bites had the characters belongnig to a much lower horizon than that assigned to them by Adams, Rogers, and Logan, was well known to Prot^ Hall, who, however, described them as occurring in the Hudson River group, and in justification thereof declared in anote, "I have the testimony of Sir AVilliara Logan that the shales of this locality are in the upper part of the Hudson River group, or form part of a series of strata listinct group, above the Science, l'2\ XXX I, ])p. which ho is inclined to rank as a Hudson River proper." (Anier. Jour, 213,2:^1). For a farther history of the question, see the au- thor's Chemical and Geological Essays, pp. i}9 1-402). FAUNA OF LEVIS LIMESTONES. E. 99 § 199. In 185G the present writer found, not far from the graptolitic Rhales of Point Levis, beds of a bluish-gray Hrae- stono abounding in organic remains. These were imperfectly preserved, but among them was a pygidium recognized as be- longing to an unknown trilobito, which was placed for exami- nation in the hands of the late Mr. E. Billings, (then recently attached as paleontologist to the geological survey of Can- ada). This was the species subsequently described by him as Bathyurus Saffordi. Farther explorations in 18o7, and succeed- ing years, brought to light a large number of species of organic remains in these and other limestone-beds at Point Levis, which Avere studied and described by Mr. Billings. § 200. A similar fauna, though less abundant, was found in the limestones of Phillipsburg and the adjacent towns of Stan- bridge and Bedford, near Lake Champlain, and also on the island of Newlbundland. Without counting the graptolitic fauna, there have been got from the limestones of these various localities 168 species of organic i-emains, of which seventy-four are crustaceans. More than one-half of these forms are met with in the limestones of I'oint Levis. Of this considiTa- ble fauna, according to Billings, five species are known in the Chazy limestone, and twelve in the Calciferous sandrock of the Ottawa basin, besides several which are found on the Upper Mississi[)pi, in strata referred by Owen to the Potsdam sand- stone, but not a single species belonging to the higher members of the Champlain division ; while the affinities of the new and hitherto undescribed species, are with the lower rather than with the higher formations of the division. From all these facts, Billings drew the conclusion that the horizon ])reviously assigned to these fossiliferous strata by the Canadian survey was not the true ono, and that their real position was at the base and not at the sunnnit of the Champlain division. From this it followed that the Gray wacke series of Quebec and Point Levis was older and not younger than the Trent(jn limestone. § 201. These conclusions were unnounced to Sir William fiO- gan in a letter to Air. Barrande, dated in December, ISGO, and published in March, 1801, (Amer. Jour. Science, [2] XXXI, 21G), when he expressed the opinion that the Gray wacke series 100 E. SPECIAL KEPOUT. T. STERRY HUNT, 1875. r. .. I of Quebec was " a great developraent of strata about tbe bori- zon of tbe Cbazy and tb(! Calciferous, brougbt to tbe surface by an overturn anticlinal fold, witb a crack and a great dislo- cation running along tbe summit," by wbicb tbe rocks in ques- tion (liencefortb called tbe Quebec grouj;),) "were brougbt to over- lap the Hudson River formation." He, at tbe same time, de- clared tbat " from tbe j)bysical structure alone, no person would suspect tlie break tbat must exist in tbe neigbborbood of (Quebec and, witbout tbe evidence of fossils, every one would be authorized t(j deny it." Logan was tbu.s led by tbe paleon- tological evidence furnisbed by Billings to adopt tbe conclu- sion as to tbe age of these rocks whicb bad been maintained by Emmons since 1846, wben the latter declared tbat tbe series wbicb be bad previously referred to tbe Hudson River group, in eastern New York and Vermont, was a modification of tbe Calciferous sandrock, protean in character, and including a great mass of sandstones, shales and limestones (§ 95, 90, 98). This priority on tbe part of Emmons was thus statod by Lo- gan in the letter above cited, "Prof. Emmons bas long main- tained, on evidence wbicb bas been much disputed, tbat rocks in Vermont whicb, in June last, I, for the first time saw, and recognized as equivalent to the magnesian part of the Quebec group, arc older than the Birdseye formation (tlie basal beds of the Trenton). The fossils wliicb have this year been ob- tained at Quebec pretty clearlj* demonstrate tbat in this he is right " § 202. These were the rocks which Emmons described, in 1840, as superior to the Granular quartz-rocK, the Stockbridge limestone, and tbe Magnesian slate (wbicli constitute the lower portion of his Taconic s\'stem,) and included under the general name of the Taconic slates (§ 103). It was tliese wliicb, in 1855, he separated from tbe lower members and distinguished by tbe name of Ui>per Taconic. This latter division be de- clared to contain, in its ui)per portions, tbe remains of grapto- lites, fucoids and crustaceans (§ 104, 107). Although at an earlier date Emmons bad spoken of bis Taconic system as in- ferior to the whole of the Champlain division, this view was subsequently confined to the Lower Taconic, since the Upi)er THE QUEBEC OR UPPER TACONIC GROUP. E. 101 ob- , in i( Ige iwer oral I, ill ;he(l (le- |pto- an in- [was L)er Taconic, as defined in his Ainerican Geology, included not only "the modified and protean Calcil'erous sand-rock," but tlie Pots- dam itself (§ 114). It is apparently by one of those inconse- quences already noticed (^§ U3) that in the same work, in his account of the Granville section (§ 108) he makes the Taconic slates to underlie the Calciferous sandrock. To Emmons un- doubtedly belongs the credit of having first discovered tiie true horizon of these Upper Taconic rocks, which was sub- sequently established, independently, by the paleontological studies of Billings. § 203. Logan, however, as we have seen, did not adopt for tliese rocks the name of Upper Taconic, which liad been pre- viously given them by Emmons. Keferring to the description of the Graywacke series given in § 181, it will be remembered that, in 1855, the rocks there included in division 5 had been called the iSillery, while divisions 1-4 had been designated the Quebec formation. Eor the latter, the name of Levis was now substituted, and these, together with the Sillery, were called, in Logan's letter to Barrande, the Quebec group; of which a section, with measurements, as displayed in the island of Or- leans, was first given in the Geology of Canada (18G3), page 227. In the Report of 18G3-6G (page 41), for greater con- venience in tracing out the supposed parallelism between these strata and the crystalline rocks of the Notre Dame range, there was established a third division in the Quebec group, by giv- ing to its middle portions the name of the Lauzon formation, taken from the seigniory of that name, in which I'oint Levis is situated. § 204. The Levis formation, as thus limited, included divi- sions 1-9 of the Orleans section (above rel'erred to) comprising 1,285 feet of green and gray shales, often dolomitic, together with some sandstones, limestones and conglomerate layers. About midway in this formation is a belt of gray argillaceous shales holding Pliyllograpliis typus ; while other organic forms, obscure and undetermined, occur in calcareous beds, both above and be- low this belt. The Lauzon formation, including tiie divisions 10-17 of the Orleans section, n»easures 3,740 feet, and consists, like the pre- vious one, of sandstones, conglomerates and shales, in winch :• 'r I I ff' i I i I hi i 1 02 E. SPECIAL REPORT. T. STERRY HUNT, 1875. red and purple colors often })revivil, especially towards the sum- mit, where is a mass of 1,000 feet or more of red shales, well seen at Cape Rouge, in which occur a species of Lingula and Oholella preMosa. Near the hase of the Lauzon are several hundred feet of soft shaly sandstones, containing in parts, abundant green grains of glauconite, analyses of which will be found in the Geology of Canada, page 486. § 205. To the Lauzon succeeds the Sillery formation, not seen in the Orleans section, consisting of greenish, drab- weath- ering sandstones, colored by chloritic matter, and holding scales of mica and of graphite, together with small fragments of green and black slates, often calcareous, and becoming, in some layers, a quartzose conglomerate. These sandstones, like the beds of the two formations just described on Orleans Island, dip to the southeast at an angle of about 50°. Mr. Billino-s united with the Sillery the mass of red shales assigned by Logan to the summit of the Lauzon, which contain in two localities the Oboldla named, and are interstratilied with the green sand- stones, from which they cannot he separated. (Paleozoic Fos- sils, Vol. I, pages 62, 69.) The thickness of these sandstones was by Logan estimated at 2,000 feet, making the total volume of the Quebec group, as defined by him, a little over 7,000 I'ect. The lithological and chemical characters of these green chlo- ritic sandstones of the Sillery formation have already been described. (§ 183, 184.) § 206. It is noteasy to identify the different sub-divisions of the Orleans section, either in the city of Quebec or at Point Levis. Much interest attaches to the latter locality, because it is there that have been obtained the organic remains which have been relied upon to fix the geological horizon of the Quebec group. It will be well, in the fi.r8t place, to consider some of the litho- logical peculiarities of the strata here met with, as described by the present writer in 1856. The rocks at Point Levis present interstratifications of pure limestones, dolomites, sandstones and argillaceous shales. " Both limestones and dolomites are very irregular and inter- rupted in their distribution, the beds sometimes attaining a considerable volume, while atother times they thin out, orare re- placed by sandstones. The limestones freciuently form masses of ill LIMESTONES AND DOLOMITES OF LEVIS. E. 103 many feet in thickness, which are without visible marks of stratification, and destitute of organic remains. These masses are compact, conclioidal in fracture, sub-translucent, and exhibit a banded agatized structure, which leads to the conclusion that they are chemical deposits from water — in fact, veritable travertines. Their colors are pearly grey of different sliades, and occasionally pale green ; they weather smooth and wliite. Analysis shoAvs that they are pure car- bonate of lime, and contain neither silica, iron, nor magne- sia, in appreciable quantities. Interstratilied with these travertines, however, there are beds of tine granular opa(pie limestones, weathering bluish-grey, and holding, in abund- ance, remains of othoceratites, trilobites, and other fossils, which are rejilaced by a yellow- weathering dolomite. ' ' These have been already noticed in § 199. § 207. "The dolomites occur both among the travertines and the fossiliferous limestones, sometimes in small lenticu- lar masses, or in layers of a few lines, interposed in nuisses of limestone. At other times the layers of dolomite are several feet in thickness," Unlike the associated lime- stone, the dolomites contain an admixture of sand and clay, and from live to ten per cent, of carbonate of iron, wliich causes them to weather reddish-brown. They are slightly bituminous, and include grains of pyrites and veins of cal- cite, but were never found to contain fossils, and often pass into a dolomitic sandstone, with rhombohedral cleavages, due to the crystalline matrix. In one example, a com])act ferriferous dolomite contained half its weight of claj'ey matter. It is chiefly these mag;nesian beds which become conglomerate. "In addition to sand and clay, the dolomites frequently enclose grains and rounded fragments of lime- stone and of dolomite, ])oth seemingly derived from adja- cent strata, so tiiat we have beds consisting of pebbles of limestone, often having the characters of the travertine, of dolomite, and occasionally of quartz and of argillite, the whole cemented by a ferriferous dolomite. At other times the cement of the conglomerate is a ncaily pure carbonate of lime." (Report for ISoB-SO, pages 464-466). These im- m li! \ 104 E. SPECIAL REPORT. T. STERRY HUNT, 1875. bedded fragments of argillite are purplish or gi-eenish in color, lustrous, and sometimes apparently chloritic. § 208. Some of tlie finely granular gray limestones above described, which contain small patches and layers of yel- lowish dolomite, and moreover hold organic remains re- placed by the same material, have, although in nowise con- glomerate in their t)rigin, an aspect which suggests the con- glomerates already noticed, and have often been mistaken for them. Such is the nature of some, at least, of the cal- careous bands which have yielded the organic remains at Point Levis. BathyuriLS Saffordi., a typical species, was first found in abed of compact limestone, not conglomerate, and Logan satisfied himself, as he tells us, that the fossils collected by him are of the age of the strata. Certain of the forms there obtained, he afterwards thought, might be included in masses derived from older strata, but he de- clared, in accordance with the views above expressed, that "some of the fossiliferous porticjns of the Point Levis bands, having the same color and texture as the supposed boulders, possess the character of original sediments, or of concre- tionary masses, and it is difficult to separate the fossils of these from those of the rolled masses." (Geology of Can- ada, page 8G0. ) § 209. The strata of Point Levis contain two unlike fau- nas, which are found in unlike rocks, and in localities en- tirely distinct from one another. We have, in the first place, a series, chiefly of argillaceous shales, abounding in graptolites ; and in the second, a series of bands and len- ticular masses of limestone, sometimes apjiarently conglom- erate, which hold a remarkable trilobitic fauna, and are in- terstratified with sandstones, and with shales which are distinct from those mentioned above, and have yielded no graptolites. Both of these Avere, however, by Logan, in- cluded in the Levis division of the Quebec group. The distinction between these two fossiliferous formations is not made clear in the Geology of Canada (page 8C1), where these rocks are briefly described. The plan of Point Levis, there referred to, however, which is published in the Atlas, and is on a scale of three inches to a mile, shows the course i GRAPTOLITIC SUALES OF LEVIS. E. 105 of every band of limestone, the outcrops, and the various localities from which fossils have been collected. "With this, and its accompanying section, aided by the description given in the letter of Logan, (§ 2ul,) the following state- ment of the relations of these rocks will be intelligible : The strata at Point Levis, with a high south-east dip, rise rai)idly from the shore of the St. Lawrence, which is paral- lel to their strike, and form a succession of bold ridges, at- taining a height of 400 feet or more, across which, by a series of undulations, the limestones, congh)merates, and shales (^f the Quebec group are distributed over a breadth of more than two miles transverse to the strike. In this distance they exhibit two well-marked iinticlinals, with in- dications of a third. The intermediate synclinals are sharp and, according to Logan, are overturned, so that the strata on both sides dip steeply to the south-east. § 210. Near the lower ferry at Point Levis is a cliff about 100 f'jet high, composed of shales, with thin-bedded lime- stone and some conglomerate layers, the whole dipping to the south-east at a high angle. The strata, whi(;h are dark gray, and very tender, abound in graptolites and related forms. Prof. James Ilall has described from this locality not less than forty-two species, which are thus divided among the following genera : Graptolilhus^ 25 ; Retlolites^ 1; lldeograptus^ 2; PJu/Ilograj)tus, 5 ; DendrograpLas^ 3 ; TJiaiiinograptus, 3 ; Didijom.ma^ 3. With these were found species of brachiopods described by Billings under the names of Lingula Irene, L. Quebecensis, and Ohol- ella desiderata, besides an Ortliis and n >Strop)honiena, both undescribed, and in the accompanying limestone an un- named Tetradlum, a minute trih)l)ite, which was desciihed under the name of Shumardia granulosa,* and another undescribed, which was i-eferred to Dikellocephalus. §211. Leaving this belt of fossiliferous strata, we ascend the coast ridge, and reach what is describ'd on the plan as the middle ridge. Here, at a point of about five eighths of HI! *This, by a typographireil error in the Geology of Canada, (page 8(54) is plaood ill oolnnin I, instead of A, where it belongs. See Billings, Paloow>ic Fossils, page 93. « 100 E. SPECIAL KKi'oirr. t. 8TKKi:v hint, 1876. a mile east of tlie giaptolitic shales, and three eighths of a Tiiile across the strike from the line of these, we find the iirst of the limtjstone beds with the trilobitic fauna, which is coiitinfMl to certain limestone bands marked on the plan, (and in tiie Geology of Canada,) 2-8, numbering to the south-east ; the whole occupying a breadth of less than a quarter of a mile across the strike. Not one of the fifty species found in the graptolitic zone to the north-west has been here met with, and, with the excejDtion of an undescribed Dlctyonema, not a single spe- cies belonging to the order of the Graptolitidea?. The species from these limestones catalogued by Mr. Billings, are 103 in number, of which 69 have been described. Pass- ing over the long list of brachiopods, gasteropods, cepha- lopods, etc., we find not less than 31 descril^ed species of trilobites, divided as follows among the genera named : Af/nosius, 3 ; Amjjliiori^ 1; AriuneUiis, 2 ; Asaphus^ 2 ; Bathyurns^ 8; Cheirurus ; ConocejjJiaUies {Conocorphye,) 1 ; DlJielloceplialits, 7 ; Eiidymioji, 1 ; Holometopus^ 1; Menocephahis^ 3; besides one each of JVileus, Amj^yx, and Jllanus, undescribed. Of these, the last two named are found, with J/oJomelopvs, only in bands, while one species of Batliyurua occurs in band 2 ; all the others being confined to the bands 3 and 4, and often common to the two. These contiguous bands weie, by Logan, regarded as the same one, repeated by a dislocation or, as he afterwards sup- posed, by an overturned synclinal fold. § 212. A few of the organic remains found at Point Levis have been observed on the island of Orleans, but it was conceived by Logan that both the graptolitic and the tri- lobitic zone were included in the iirst ten divisions (measur- ing about 2,000 feet) of the Orleans section, in which he did not attempt to iix the relative positions of the two fossil- iferous horizons. He however noticed (Geol. Canada, page 280) that the argillites between the limestone bands at Point Levis often include red layers, in which respect they differ from the lower portion of the Orleans section, designated the Levis formation; while, on the contrary, the upper part of that section, referred to the Lauzon, has red FOSSILIFEUOUS LIMESTONES OF LEVIS. E. 107 argillite bands at several horizons; thus niakinf^ it proV)able that a large portion of the Levis section belongs to the so- called Lanzon. It will be remembered, however, that a thick band of argillaceous shales, holding PlnillorfraptuSy and the supposed equivalent of the graptolitic zone at Point Levis, is found in the Orleans section, about 700 feet from its base. § 213. Billings published his first account of the fauna of these limestones in the Canadian Naturalist, in August, 1860, and Barrande, commenting thereon, in 1801, (Bull. Soc. Geol. de Fi'ance, 2me sdrie, tom. XVIIl, page 203,) called at- tention to the fact, tliat while the limestones of band 3 (No. 1 of Billings) had, at that time, yielded triiobites of the ge- nera, Arwnellu.s, Dikellocephahis, Menocejplialus, and Von- ocoryphe^ the band 4 (No. 2 of Billings) contained none of tliese, but only Bathyurus and A(/nostys, witli Chei- riirus. This latter genus, together with associated lirach- iopods and species of Orthoccras and Ci/rtoccra-s, lead him to refer the band 4 to his second fauna; wliile the band 3, according to Barrande, belonged clearly to the first or i)ri- mordial fauna. Subsequently, liowever, Billings found Or- thoceras in 3, while two species of DikeUocepJialus were de- clared to be common to 3 and 4, and he was led to believe, with Logan, that the two bands, if not identical, belong to the same liorizon, and present an admixture of forms belonging to the two faunas. § 214. At a later date, in 1863, Billings expressed the opin- ion that the forms at first described by him as species of Arionellus, sliould be referred to tlie new genus Ftychaspis of Hall, from the western Potsdam, which would also in- clude one of the Levis species previously called a Dikello- ceplialus. A new genus, LogaiielluH^ proposed by Devine for a trilobite from Point Levis, at first referred to Olenus^ will include, according to Billings, other species of the so- called Dikdlocephaliis^ as well as some of the western forms referred by Shumard and ])y Hall to Conoceq^halile.s. Bill- ings now expressed th*^ opinion that the Levis belonged to a somewhat later pei-iod tlian that of the lai'ge si)ecies of Paradoxides, and declared that we have, in the Levis lime- Hi !ii 108 E. SPECIAL RKPOKT. T. STERRY HUNT, 1875. stone, " the leadin<^ generic types of the dominant family of the Potsdam trilobites." (Pal. Fossils, pages 198-200.) This was in accordance with the declaration by Professor Ihill, in 1801, that, judging from its trilobitic fauna, the Levis limestcme "is in parallelism with the Potsdam and Calcif- erous strata." {American Journal Science, [2,j xxxi., 222.] § 215. The rocks now included in the Quebec or Hudson River group by Logan, were, however, found to contain still another fauna, which included the two species of Olenellus described by Hall from Georgia, Vermont, (§ 198.) The Red sandrock of that vicinity has also yielded two species of Con- ocorifphe and an OholeUa, besides, according to Perry, crin- noidal stems. Subsequently, these same species of Olen- ellus, together with the ConocorypJie, were discovered in a limestone at Forteau Bay, on the north side of the strait of liel lisle, with three species of Bathyurus, Sallerella, and ArcJieocyathus, besides numerous brachiopods, including the Oholella found in the Red sandrock of Vermont. These limestones, associated with red and green shales, have an observed thickness of 143 feet, and overlie conformably a mass of nearly liorizontal red and grey sandstones, often conglomerate, which rest upon Laurentian gneiss, and are made up of its ruins. Many beds of these sandstones, which have an aggregate thickness of 231 feet, are penetrated ver- tically by ScolilJius linearis. % 216. On the opposite side of the strait of Bellisle, which is here from ten to fifteen miles in width, appears a belt of paleozoic rocks, stretching thence along the north-west side of the island of Newfoundland for a distance of 180 miles to the south-west. It is limited to the south-east by a par- allel range of crystalline rocks, in part Laurentian. Akmg the shore, this belt of sedimentary strata lies nearly horizontal, but where we can examine the strata to the south- east, across the strike, as at Pistolet Bay, which is at the north-east extremity of the island, and at Bonne Bay, 180 miles to the south-west, they are found to be greatly dis- turbed, faulted, and often inverted as we approach the crys- talline range. This region was examined by Mr. James Richardson, in 1801 and 1802, and from his notes and col- STRAIT OF BELLISLE, NEWFOUNDLAND. E. 109 lections the officers of the Canada Survey prepared the de- scriptions given in the Geology of Canada, (pages 287-21)3, and 804-880.) § 217. The arrangement of these rocks on the two sides of the strait of Bellisle is supposed to be tliat of a sliallow synclinal. A series of beds on the island, chietly of sand- stones and niagnesian limestones, believed to follow the beds already noticed on the mainland, and making, with these, a total thi(;kness estimated at 1,147 feet, was de- scribed under the name of the Potsdam group. Succeeding these are not less than 3,200 feet of limestones which, from their organic remains, were referred to the Calciferous for- mation. To this succeed 1,400 feet of limestones, often conglomerate, with black shales, supposed to belong to the Levis formation, which, at that time, included the Lauzon division. (§ 203.) These rocks, along the north-eastern part of the belt, present very slight inclinations to the south-east, but farther to the south-west, where the crys- talline range is nearer the shore, they are affected by un- (lulati(ms running north-east and south-west, and are highly inclined to the south-east, and sometimes even ver- tical in altitude. § 218. At the south-western extremity of the belt exam- ined, where Bonne Bay affords a transverse section, there is found a series of blackish-blue argillites, with transverse slaty cleavage, interstratified with, and underlaid by gray quartzites. This group, with a thick]; 3ss of GOO feet, and without observed fossils, is followed by a series of lime- stones with shales and sandstones, estimated at 1,400 feet, holding organic remains like those of the Labrador coast, and hence referred to the Potsdam group. Other fossil- iferous strata of the series occur in the neighborhood, but "they are much contorted, and it is dilTicult to make out the true succession." Overlying these, in conformable sequence, appear 2,000 feet of greenish sandstones and shales, referred to the Sillery formation, the whole dipping south-east at angles of from 45° to 80° ; while further to the south-east, across an arm of the bay, rises a mountain of serpentine, with talcose slates, more than 2,000 feet in height. iVi tr 110 E. SPECIAL REPORT T. STERRY HUNT, 1875. ^1 2: It 'H. j t[ § 219. At Cape Norman, at the north-easi extremity of Newfoundland, most of these fossiliferous strata appear, at first witli moderate dii)8 to the soutli-east, but, in tliat direc- tion, soon become affected by great undulations, and are o+'ten vertical or even overturned along the west shore of Pistolet Bay, where the fossiliferous limestones and slates are seen, devoid of any crystalline character. On the east side of the same bay, is a mass of hornblendic, feldspathic, and chloritic rocks, interstratiiied with serpentine and dial- lage-rock, the whole estimated at about 1,200 feet in thick- ness. Succeeding these, on the south-east side, is a great de- velopment of chloritic sandstones and conglomerates, which (jccupy a breadth of several miles, and are supposed to rei)resent the Sillery formation ; which here occurs, not be- tween the fossiliferous sediments and the serpentines, as at Bonne Bay, but separated from the former by a mass of sim- ilar serpentines. The rocks in Pistolet Bay are ailecred by four dislocations, one of which is supposed to be a down- throw^ of about 1,400 feet to the south-east side, "while the other three are up-throws to the south-east." Several other similar dislocations, running with the strike, or nearly so, are observed further south-west, towards Bonne Bay, "all of them being up-throws on the south-east side." (Geol. Canada, page 87G.) § 220. After a further and careful study of the collection of fossils from these Newfoundland rocks, Billings declared that the chai";cteristlc fauna of the Levis limestones (found also at Phillipsburg and Bedford, near Lake Champlain) had been met with in Newfoundland, only at Cow-Head, a point not far from the south-west extremity of the belt of fossiliferous strata. He also recognized a series of beds holding the organic remains of the typical Calciferous sand- rock of the Champlain division. These strata, however, if we may trust the observations, do not immediately underlie the Levis limestones, but are separated from them by more than 2,000 feet of limestones containing a fauna distinct alike from the Calciferous and the Levis. While including some si)ecies belonging to the Cliazy. and others very simi- lar to, if not identical with those of the i^Iack Kiver nn III! 114 E. SPECIAL REPORT. T. STERRY HUNT, 187i), recollected that the crystalline rocks of the Notre Dame range had been by Logan asserted, in accordance with the hypothesis of Mather, to be formed by a metamorphosis of the strata of the Quebec gronp, and a horizon of serpentinic, hornblendic, and chloritic rocks, wa.s supposed by him to occur at the summit of the Lauzon fonnation. At Bonne Bay, as described, the uncrystalline fossiliferous limestones and shales were seen to dip south-east, at a higii angle, apparently beneath a conformable mass of the Sillery sand- stones ; while a little distance across the strike crystalline rocks, like those of Notre Dame range, rise in a mountain- mass. § 227. At Pistol et Bay the fossiliferous strata are also seen dipping to the south-east at a high angle towards a belt of similar crystalline rocks on the opposite side of the bay. Here, the Sillery sandstone is not seen in the interval, but appears on the south-east side of the belt of serpentinic, .?blovitic, and hornblendic rocks. Upon this relation of things, Logan remarks that the crystalline rocks here oc- cupy their supposed position, towards the summit of the Quebec group, while the massive greenish chloritic sand- stones succeeding them "would thus appear to occupy the horizon which has been j^rovisionally assigned to those of the Sillery formation, near Quebec," adding that "further research, however, is yet required to establish«the true re- lation of this formation to the Quebec group." (Geol. Can- ada, page 880.) § 228. The ])i'esent writer has, for many years, believed that the position of the Sillery sandstones is at the base, instead of at the summit of the Quebec group, and that the whole series is more recent than the crystalline rocks of the Atlantic belt, to which the Notre Dame and Shickshock ^[ountains, and the similar crystalline rocks in Newfound- land (^ 218) belong. The order at Quebec, according to this view, is a reversed one, due to an invei i.ed fold, while the dl[)i)iiig of the uncrystalline strata southwards towards the ciystalline rocks, and apparently beneath them at Bonne Bay and PistoletBay, is connected with the numerous faults whicli, with up-throwson the south-east side, liave been no- RELATIONS OF THE SILLEKY FORMATION. E. 115 lase, the the lock jiui- Ithis the the Inne lilts no- ticed at the latter locality (§ 219.) These phenomena, alike at Quebec and in Newfoundland, are in close accordance with those seen everywhere along the north-western base of the Atlantic belt, from Virginia to Gaspd, as so abundantly established by the concurrent testimony of the Messrs. Ro- gers, Mather, Logan, and Emmons, already set forth. (§ 16, 72, 75, 109, 110, 177-179.) § 229. The normal position of the Sillery is, according to this view, seen to the south-east of Pistolet Bay, where the Sillery sandstones succeed to the crystalline rocks. Sedi- mentary beds of this kind take their character from the ad- jacent crystalline formations, and as the serpentinic, horn- blendic, and chloritic rocks furnish, by their disintegration and decay, very different materials from the Laurentian gneisses of the Labrador coast, we fine ;:he Sillery sand- stones and shales unlike the basal beds of that region, or of New York, and central Canada. It will be recollected that Emmons, in describing the Upper Taconic (Quebec) series, asserts that its basal beds are greenish chloritic sandstoi.es and conglomerates, formed from the ruins of the crystalline rocks, and sometimes seen to rest directly upon them. (§ 107.) As the results of repeated dislocations, with up- throws in the eastern side, however, the whole order is gen- erally, according to him, apparently inverted ; the black fossiliferous shales of the summit appearing to dip eastward beneath all the other members, and the greenish sandstones seemingly overlying the whole, as seen in the Granville sec- tion. (§\o7-ll().) § 230. The present \vTiter urged, in 1872, that the Levis limestones, which apx)arently correspond to the Tremadoc rocks of Great Britain, occupy in the Quebec section a po- sition nearer to the Sillery than does the graptolitic zone, which is clearly the equivalent of the less ancient Arenig or Skiddaw rocks ; from which follows the stratigraphical in- version of the whole series. (Ohem. and (UhA. Essays, pages 412-41:5.) Tills view was shared by Mr. Billings, who, in a private communication, in January, 1870, shortly bel'on? his death, informed the writer that the Obolella preihsa of the Sillery is apparently identical with 0. maculala. Hicks, 110 E. SPJX'IAL REPORT. T. STERRY HUNT, 1875. i'M from the Meneviiin of Wales. He had also recoy,iiized (JftliU HicksU, Salter, a Menevian species, in the Lauzon, or so-called Lower Potsdam beds of Bic Harbor. (§ 223.) § 231 . The north-western lindt of the strata of the Quebec uroiip, in Canada, is nearly defined by a line running from (Jape Rouge, in the vicinity of Quebec, to the northern ex- trendty of Missisquoi Bay, on Lake Champlain. The rocks to the south-east of this line, including alike the fossiliier- ous strata, and the ci-ystalline rocks of the Notre Dame range, supposed to })e the same strata in an altered condi- tion, were described by Logan as l)eing Jirranged "in long, narrow, parallel, synclinal and anticlinal forms, with many overturn-dips. The latter circumstance makes it diliicult to determine which of these folds are synclinal, and which anticlinal, inasmuch as the outcrops in both cases present a sinnlar arrangement. Tlie weight of evidence, however, goes to show that the strata dij) to the centers of the areas about to be described, and they will, therefore, be designa- ted as synclinals." They were declared, in the region in question, to be three in number, of which the first, or north-western one, included the uncrystalline strata al- ready described in some detail, as seen near Quebec, at St. Flavien, on the St. Francis, at Acton, Ui)ton, and Wick- ham, at Granby, Farnham, Bedford, and Phillipsburg. (Geology of Canada, pages 234 and 790, and Report for 1863-6(5, pages 29-39.) § 232. The evidence above alluded to was that deduced from the section near Que})ec, according to which it was supposed that the Sillery sandstones were the highest rocks, and appeared only in the deeper parts of the first synclinal, wliich was partially divided by subordinate anti- clinids into lesser basins. Certain carbonaceous slates, with thin beds of sandstone and impure limestone, which appear upon the supposed anticlinals, were, by Logan, conceived to be older than the Quebec; group, and referred by liim to the Potsdam. These, however, were found at Farnham to contain many organic remains, among which, according to Billings, are trilobites belonging to the genera Ampyx, Dalmanifes, Liclias, Trlarthrus, and Agnostiis, together BLACK SLATES OF FARNHAM. E. 117 with undescribed giuptolites, a Leptaena like L. sericea, and a Plllodlctf/a like P. acuki. These forms, it was said, are not what "might be expected in the Potsdam forma- tion, so tliat the Farnham slates, with similar ones in other localities, may be brought into position by some of the many complicated dislocations which affect the strata. Except, however, where such fossiliferous strata are knf)wn to occur, (he black slates and limestones will be provision- ally described as older than the Quebec group." (Geology of Canada, pages 2;U, 236, 239, 240.) Subsequently, how- ever, Logan declared with regard to these black slates and limestones, supposed to be related to the Potsdam group, that it " appears to be difficult to separate them from the Phillipsburg rocks, and these being paleontologically con- nected with the lower 1,285 feet of the Levis series, the whole naturally constitutes one group." The original Levis formation was now first divided, and it was said that the "lower or Levis division comprehends the Phillipsburg series, the black shale above it, autl the lower 1,285 feet of the Orleans section." The remainder of this last was called Lauzon. (§ 203.) (Report for 1853-66, pages 30-31.) The pages here quoted, though bearing the name of Mr. James Richardson, were written by Sir W. E. Logan. § 233. The black slates or shales, now included in the Levis formation of the Quebec gronj), (and placed higher than the Phillipsburg limestone,) were thus the same whicli, from their relations to the folded stratii in the supposed north-western synclinal, were at one time conceived to un- derlie the whole Levis or Orleans section, and were still placed at or near its base. From their fossils, however, these slates belong to a liorizon above that assigned to the Quebec group, and corresi)ondiiig to the Trenton, or the still higher members of tlie(Jhaniplain division. Wc have tlius a fourth fauna included in the Levis formation, (;^ 224.) If, however, as we have endeavored to show, the position of these black shales is really at the summit and not at the base of the so-called Quebec group, whicli is an inverted series, the anomaly disappears, and we have, in ascending order: — 1°, the Sillery sandstones ; 2°, the trilolutic beds of 5 ii :t. i j 118 E, SPECIAL REPORT. T. STERRY HUNT, 1875. Levis and Phillipsburg ; 3°, the Pbyllograptiis shales of Quebec ; and 4°, the black shales of Farnham ; — in whicli the succession is in accordance with the well known facts of paleontology. § 234. We may here notice the judgment of Prof. James Hall at this stage of the inquiry. He had hitherto em- ployed the name of the Hudson Iliver group as synonymous with the Loraine shales ; but in 18G2, in a note to his Ge- ology of Wisconsin, page 443, he referred to the evidence of organic remains recently found in the Hudson Iliver slates in Vermont and Canada, "which prove conclusively that these slates are, to a great extent, of older date than the Trenton limestone," although probably posterior to the Potsdam. He remarked, moreover, that " the occurrence of well known forms of the second fauna — LeptcBna serlcea, Orthls tesiudinarla, Asaplms {Isoielus\ Tri nucleus, etc. — in intimate relation with, and in beds apparently consti- tuting a part of, the series along the Hudson liiver requires some explanation. Looking critically at the localities in the Hudson valley which yield these fossils we find them of limited and almost insignificant extent. Some oi" them are at the summits of elevations which are synclinal axes, * * where the remains of newer formations would naturally occur. Others are apparently unconformable to the rocks below, or are entangled in folds of the strata, * * while the enormous thickness of beds exposed is almost destitute of fossils." The graptolites of the Hudson valley, "which have hitherto been referred to the age of the other fossils found in the small outliers, or to the second fauna, in reality hold a lower position, and belong to the great mass of slates below," He concluded that, inasmuch as the Hudson River rocks, in their typical localities, are, as a body, older than the Trenton limestone, which is itself older than the Loraine shales, and the shales and sandstones of Pulaski, "the term Hudson River group cannot properly be extended to these rocks, Avliich, on the west side of the Hudson, are separated from the Hudson River group proper by a fault WING ON THE GEOLOGY OF VEHMONT. E. 119 lat 3ks, the line the to are I lilt not yet fully ascertained." See further § 237 and for the Pulaski rocks the note to § 249. § 235. There are not wanting evidences elsewliere that the fauna of the upper half of the Cham plain division is in- cluded in this disturbed belt. The obstM-vations of the Rev. Augustus Wing, and those of Mr. Billings, in Ver- mont, which are to the point, were described by tlie present v^Titer in a communication on the Geology of Vermont, read before the American Association for the Advancement of Science, at Chicago, in 1868. In a section from Crown Point, in New York, eastward across Lake Clia.mplnin to Bridport, in Vermont, the western part exhibits the whole succession of the Champlain division, from the Potsdam sandstone to the Loraine shales, which are overlapped by the Red sandrock, as already described (§ 116). This, dii)ping to the east, is overlaid by a great mass of limestones, seen in Sudbury, which yielded to Wing and to Billings the fauna of the Calciferous sand-rock, with other forms like those of the Levis limestone. Next in ascending sequence, also in Sudbury, was found a mass, estimated at not less than 2,000 feet, of limestones holding, in abundance, the fauna of the Trenton, and probably including tliat of the Cha7y\ To the east of this, again, a fault, marked by a ravine, brings up against the Ti-enton the Levis limestone, from which Mr. Billin,u:s obtained numerous characteristic fossils, including Balhiiunis ^affordl. Tliese fossils abound in Sudbury, Cornwall, Middlebury, and Brookville, where, according to him, they are closely associated with the white marbles quarried in this region. (Amer. Jour. Science [2], XLVI, 227.) This succession recalls the section in New- foundland (§ 220) with foi'ms apparently of Trenton age, and raises the question whether a careful study of the latter locality might not show the presence of the higher members of the Champlain division. § 236. The strata in this section examined by Wing and Billings, appear in their normal order, and, though alfected by undulations, and by great up-throwson the eastern side, are not inverted. Further northward, however, Logan found remarkable examples of inversion, one of which is ■ s '■ ■ r^f 120 E. SPKCIAL liKPOUT, T. STERRY HUNT, 1875. ill seen near Hi<;h<^ate Springs, where the Trenton limestone, on the west side of an anticlinal, becomes vertical, and in places assumes an eastward dip. About eight miles further south, at Smith's lime- works, the Trenton limestone is over- tuiued and overlaid in successicm by the Black River lime- stone and by a series of sandstones and dolomites regiirded as belonging to the Chazy. The whole of this inverted series, measuring about 000 feet, lias an eastward dip, ranging from 45° to 75° beyond the jjerpendicular. Within a distance of 150 yards to the east, according to I^ogan, appears the Red sand-rock, with a gentle dip to the east. It here consists of red and white sandy dolonntes, int<'rstratilied with dark- colored shales, in both of which are found the charactei'istic fossils of the Lower Potsdam, tin.' whole series having a thickness of 2,200 feet. For an account of these inverted sections, see Geology of Canada, joages 275-280, and also page 855, where designs of them, drawn to a scale, are given. § 237. In 1868, Logan, in company with Professor James Hall, exanuned the i-ocks of eastern New York which had been designated bv Eaton as Argilliteand Transition (Iray- wacke, (§61 ;) by Mather as belonging to the Hudson River group (Loraine,) and the Oneida and Medina formations, (§ 75-77 ;) by Emmons, first assigned to the same horizon, (§ 94,) and subsequently regarded as a great and peculiar de- velopment of strata of the age of the Calciferous sand-rock, (§ 96,) which he afterwards called, successively, the Taconic slates, (§ 10:3,) and the Upper Taconic series, (§ 107-108.) These rocks, described by Logan as consisting of greenish sandstones and conglomerates, with shales, sometimes red and green, and with slialy and concretionary limestones, including the Sparry lime-rock of Eaton, were declared to belong to the Quebec group. They were described as occu- pying nearly the whole of Rensselaer, Columbia, and Dutch- ess counties ; the Sillery formation being largely developed in the first-named county, but scarcely extending south of it. To the westwtird, in approaching the river Hudson, these rocks were replaced by the lithologically distinct and more recent strata of the Loraine formation, a narrow belt of whiidi was traced along the east side of the river to a point a little LOGAN ON THE QUEBEC (iUoUP. E. 121 le- u- h- Ire le above Hyde Park, where the houiuhiry between the two for- mations crosses to the west bank, and the slates and lime- stones of the Quebec j^roiip thence occupy both sides of the river down to the Highlands, which were declared to be of Lainvntian age. The results of these investigations are stat«'d in a note prei)ared l)y the present writer, with the approval of Sir William Logan, and published in the Cana- dian NatiLTalist, in 1804, (vol, I, page 809.) They are also embodied in the geological map of Canada. (,^ 44.) § 288. What were the relations between the older rocks, whether called Lower Potsdam or Quebec gi'oup, and the higher members of the (Jhamplain division found along their western border; We have seen that Logan had foruicrlv supposed, with Mather, that this line marked a great anti- clinal axis (§ 195.) The later view of the Quebec group, arrived at by Logan, in 1801, made this hypothesis no longer tenable, and a new one was put forward by him in 1801, in the Canadian Naturalist, (vol, VI, page 199, which is set forth in the G-eologv of Canada, (pages 294-297.) The new hypothesis supposed that tlie whole series of rocks, includ- ing the Potsdam and Quebec groups, and the succeeding Trenton, Utica, and Loraine formations, had been laid down confornia])ly, and without disturbance. Logan conceived that the deposition had taken place along the south-east border of a Ljiurentian continent, and that \\ liile the great accumulations of the Potsdam and Quebec groups were going on, the typical Potsdam sandstone and the Cal- ciferous sand-rock of the New York series were laid down over an adjacent terrace or shallow basin, which was sub- merged at intervals. It was not until the close of the Cham- plain period, that a great break, with an uplift of 7,000 feet, was imagined to have lu'ought up the lower strata on the south-east side of th«^ dislocation, causing them to over ride the broken edges of the higher formations. This supposed line of break and upthrow of 7,000 feet, was coincident with the former anticlinal axis of Mather and Logan (§ 09- 71, 195), and was now said to extend from Gasp^ to Ala- bama. § 239. Such a dislocation, so near the continental border, . Jr ■ t« 122 E. SPECIAL REPORT. T. STERRY IIITNT, 1875. it was sought to explain by assuming for the shore of the ancient continent, a gi'eat heiglit and a very steep inclina- tion. In the word.s of Logan: "During the Potsdam period, in the neighborhood of Quebec, we see that the sur- face of the quartzo.se gneiss now supporting the Trenton limestone at the Falls of Montmorenci, must have been 7,000 feet above the gneiss under the Island of Orleans, while the distance between the two posi^^'-^ns does not much exceed a mile and a half. This wo jive a slope of nearly 45°, and perhaps it would not be oxlravagant to take this as representing the inclination along the whole line to Alabama. As the Potsdam and Quebec groups ac- cumulated, their edges would abut against this slope, and ultimately both these and the early shallow- water deposits on the higher terrace (the typical Potsdam sandstone and Calciferous sand-rock) would be covered over" by the Tren- ton limestones and Mie Utica and Loraine formations. This supposed condition of things was illustrated by an ideal diagram (page 296), in which the whole succession, including the black shales of the Potsdam at the base, are represented as horizontal strata, the Potsdam dng overlaid by the Quebec group, which, in its turn, if ^red by the Trenton and the higher formations. On pagv, 234 another diagram represents these deposits after the supposed break, in a section from Montmorenci to Orleans Island. § 240. This explanation requires, according to the admis- sion of Logan, the extraordinary condition of a mountain- range stretching from Gasp^ to Alabama, rising from the sea with "a slope of nearly forty-live degrees " to a height of 7,000 feet, which gradually subsided, as accumulation went on along its base, until it was completely submerged. The facts of the case, however, do not require any such geographical improbability to account for them, and a simpler explanation of the problem is found in the exist- ence of an unconformity between the Trenton limestone and the older members of the paleozoic series. § 241. Movements of the earth's crust, resulting in folded and inverted strata, have demonstrably taken place along the Atlantic belt at several periods. The Silurian lime- NON-CONFORMITIES IN THE ATLANTIC HKLT. E, 123 il Stones, (including those of Niagara and Lower Ilelderberg age, which constitute the Gasp^ limestones of north-eastern Canada (^ 175),) are found near Montreal, resting transgress- ively ui)C)n the erod* d edges of the Cliamplain division, and further east in like manner, both upon the strata of the Que- bec group and upon the crystalline rocks of the Notre Dame range. Throughout the Atlantic belt, in Canada, these Gaspd limestones are folded, faulted, often at high angles, f and sometimes vertical and even inverted, (Geol. of Can- ada, page 429.) In Gaspd, where they are conformably overlaid by the Devonian sandstones, fragments of both of these enter into the conglomtvate of the Lower Carl )onifer- ous, which rests upon them unconformably. This, in its turn, is more or less disturbed, and, in parts of New Brunswick, its strata appear nearly or quite vertical in at- titude. There is, in this region, a want of conformity be- tween the Lower Carboniferous and the Coal measures, which are, themselves, often much disturbed, and l)ear upon their upturned edges beds of Triassic sandstone, which, itself, is sometimes raised to an angle of 45°. We have thus along the Atlantic belt, in the provinces of Quebec and New i'runswick, evidences of at least five periods of movement, arked by parallel foldings of the strata and by unconformity, subsequent to the deposition of the rocks of the Champlain division, namely : 1, post-Siluro-Cambrian ; 2, post-Devonian ; 3, post-Lower Carl)oniferous ; 4, post- Carboniferous ; 5, peyond to Malbaie, the same is true. Beds of quartzose conglomerate, and sandstones sometiines occur at the base of the limestone in this region, but where these have yielded fossils, as at Malbaie, they are found to belong to the inferior beds of the Trenton. Again, at Lake St. John, on the Sagiienay, the Trenton is found to rest directly on the cfvstalline rocks. ' DEPOSITION OF THE TRENTON LIMESTONE!?. E. 123 ii le ?st i.t' ur se ig 11, § 245. From these facts it is plain tliat after the deposition of the Calciferous and Chazy formations, and before the time of tlie Trenton, there was a considerable contint ntal movement, by which the deep Trenton sea was widely spread over regions which had not been submerced in the earlier part of the Champlain period, and deposited its limestones to the north and east, far beyond the limits of the immediately preceding formations. (§ 99.) Still further movements took place over parts of the area in (piestion, as is shown by the du-ect supci-position of the I'ticii forma- tion npon the Primary rocks at the base of the Adiron- dacks, (§ 101,) and tlie discordant superposition of the Utica and Loraine u'pon the lower members of the Cham- plain division near Ottawa. (§ 1(H).) § 240. The movements which resulted in the oyerlapping by the Trenton of the older members of the Champlain division, do not, it is true, necesaai'ily imply discordance, but they make it possible, and, when taken in connection with the complete paleontological bivak, highly prol)aV)le. When it is considered that the alternative of denying a want of stratigi'aphical conformity at this horizon is the acceptance of the hypothesis of Logan, (§ 238,) few. we think, will hesitate to admit that tlie period immediately preceding the deposition of the Trenton must have be»'n marked, along the Atlantic belt, by a niovt'nicnt of the earth's crust, which resulted in the uplifting, faulting, folding, and frequent inversion of that great mass of sedi- ments along the western base of the Primary rocks, which constitutes the Upper Taconic series. The Trenton, Utica., and Loraine formations would then be laid down over the disturbed surface of these. ]))'ecisely as over the still older rocks of the Laurentides. in this connectiou must be con- sidered the statement of Emmons, that small aieas of the last two named formations rest un<'onformal)ly upon tlie laconic rocks, near Chatham in eastern New York. (§ !)7.) § 247. These newer rocks, including the Trenton limestone group, must necessarily have shared in all tlie later move- ments of the Atlantic belt, whicli, as we have sliown, C(m- tinued at intervals into Mesozoic time, and involved even Mjl 126 E. SPECIAL REPORT, T. STEURY HUNT, 187o. lii lii 1 1 1 'I i Devonian and Carboniferous strata. The similar foldings and inversions of the upper members of the Champlain division along the western borders of the Upper Taconic series, as observed by Logan, are completely analogous to those exhibited by the Auroral limestone along the western base of the Laurentian of the South Mountain, in Pennsyl- vania and New Jersey, as described by Rogers, ( § 10 ; ) and the facts observed by Mather in eastern New York (§ 72) are of the same order. The phenomena, in many cases, show that the older rocks did not act merely as passive barriers in these movements, but themselves yielded to the lateral pressure, so that they over-ride the newer strata, which j^ass beneath them. § 248. The boundary between the Upper Taconic or Quebec group, and the younger members of the Champlain, is, in this view, neither an anticlimil axis, as taught by Mather, and by Logan, previous to 1801 ; nor ypt a line of fracture and great uplift, as subsequently maintained by the latter ; but was primarily a line of contact, where the Trenton, and the succeeding Utica and Loraine formations, rest unconformably upon the disturbed strata of tlie Upper Taconic series. Tlie relations of the two have been more or less complicated and obscured by subsequent movements, involving alike the younger and the older series, as above described, and giving rise to many minor anticlinals, inver- sions, and uplifts, which, although secondary and subsid- iary in character, seem, at first sight, to afford some justifica- tion for both of the hypotheses previously proposed. The view that the relations of these two series is primarily one of stratigrapliical discordance, was advanced by the present writer in 1871 and 1872. (Chemical and Geological Essays, pages 203, 413.) m^ ^s, CHAPTER IV. niSTOmCAL SKETCH CONTINUED. § 249. Before proceeding to a further discussion of the various rock-fornuitions found beneath the horizon of the Trenton limestone group, it becomes necessary to consider brieily tlie nature, the succession, and the paleontological history of the lower paleozoic rocks in Great Britain and in continental Europe, and to compare them with those of North America. To this end, a tal)Ie, prei)ared with the aid of one published by Hicks, in 1875, is subjoined, in which the principal divisions of these roclcs in Great I'iritain, up to tlie summit of the P)a]a group, (which is regarded as cor- responding witli that of t he Loraine shales,*) are enumerated in ascending order, the thickness of each being given. (See, in this connection, the papers of Hicks, Qiinr. .lour. Geo- *Tho lioniiiio slmlca of Emmons conslituto tlio summit of tho .Slluro-Ciim- biian in tlio United States. Tliey were called by V'anuxem tlio ruIiiskiHlialos. and made l)y him tlu' npiicr moinbor of tlic Iludson-l^ivor cronp, wlnla tho Franl'Cl'oit s;ind.ston(!« and shales, \vhit;li In; rctiaidcd as a hiwor miMnbor of tho siuno group, \vi'ro by him oonloundoil with thu Upper Taoonio rocks. This question will bodiscus.sod at tho end of tho present ehaptor. I f ! ;r i I • 128 E. SPECIAL REPORT. T. STEKKY HUNT, 1875. logical Society, vols, xxix, 42, and xxxi, 192 ; also Hunt, Chemical and Geological Essays, pages 384-386.) LOWER PALEOZOIC KOCKS IN WALKS. Feet. VII. Bala group or Caradoc, varying in thickness from 3.000 to 12,000 VI. Llandeilo group, often much exceeding . . . 3,000 Y. Arenk. grou|j, divuletl iuti- Ujjpcr, 1,500 foot; Middle, 1,500 fcet,and Lower, 1,000 feet. he lovei' division of the Areuig abouim . in graptolites, and is e(|uivalent to the Slciddaw slates. It corresponds to wliat in North Wales ha.s been called L'pjjer Tremadoc,) 4,000 IV. Tremauoc group, 1,000 III. Linoi/la-Flao group, including Upper or Dol- gelly, 000 feet; Middle or Festiniog, 2,000 feet; and lower or Macntwrog, 2,500 feet. (The lower and niiddh' divLsions of the LingulU Flags are equivah'ut, rospoctively, to tlie ilol- lybusli sjuidstone and to the Olenus slates of Malvern,) 5,100 II. Menevian grouj), tJOO 1. LoNOMVND group,, including the Llanberris shitcs and tlie Harlecli sandstones, often much exceeding 4,000 § 250. The above series rei)resents the whole of the Cam- brian of Sedgwick, as defined by him in 1838. He subse- quently divid(^(l it into the Lower Cambrian or Bangor group, ( i) ; the Middle Cambrian or Festiniog, ( ii, iii, IV,) and the Upper Cambrian or Bahi group, (v, vi, vii,) vrhich embraced the Bala, Llandeilo, and Arenig of tiie present sc^heme. Wlien lirst named, no organic remains were known in Sedgwick's first and second groups, and the third was, by an ei'ror of IMurc^hison's, claimed as a lower nuMiibpr of his Silurian system, (which properly includes the succeeding Llandovery, Wenlock, and Ludlow forma- tions.) He, thei-eupon, called the Upper Cambrian group of Sedgwick, Lower Silurian, a name which was adopted by the greater number of geologists, both in Great Britain and North Ameiica. The name of Cambro-Silurian, or better that of Siluro-Cambrian, has been by many, how- ever, used to designate the Upper Cambrian of Sedg^^'ick, and will be so employed in the following pages. UPPER AND LOWER CAMBRIAN IX WALPIS. E. 129 111, the hius the wer lies ma- tain or low- ick, § 251. Miirchison assumed that the Siliiii:in, as thus ex- tended downward by liim, re})resented tlie dawn of life, and, when, at a later date, oi-fjanic remains, b(»l()n,iiin,£: to the so-called Primordial zone of ]3arrande, were found in lower portions of the Cambrian, attempted to annex these por- tions to his Silurian system under the name of Primordial Silurian ; restricting the name of Cambrian to the Long- niynd group, which was, at that time, still regarded as non- fossiliferous. This latter innovation of Murchison's, though adopted by BaiTande, and by the geological survey of Great Britain, who have been copied in Canada and the United States, is with reason rejected by most other British geolo- gists, and by those of Sweden, who retain the name of Canibrian for both the Lower and the Middle groups of Sedgwick. Belt, (avIio with Hicks, has greatly advanced our knowledge of these older rocks in Great Britain,) in- cludps T and II of the above table in the Lower Cambrian, while he gives to III, lY, and V the name of Upper Cam- brian, conceding for the original Upper Caml)rian of Sedg- wick, (the Siluro-Cambrian), the name of Lower Silui-ian, a nomenclature wliich Avas adopted by Lyell. In these pages, while maintaining the name of Siluro-Cambrian, the terms Lower and Upper Cambrian will be used in the sense in Avhich they are employed by Belt and by llicks. § 2r)2. The whole of the Lower and Upper Cambrian in Wales, amounting to over 10,000 feet, consists, so far as known, of vsandstones, conglomerates, and phales. The latter are sometimes calcareous, but no limestone beds have been found below the Llandeilo group of the Siluro-Cam- brian. The Upper Cambrian series, which has been care- fully studied and sub-divided by Belt, presents, accoi-ding to him, a remarkable case of inversion at Dolgelly, m Noi-tli AVales, where the strata are completely overturned, so that theapi)arent succession, in ascending order, gives the Areing, Tremadoc, Dolgelly, and Festiniog foi'mations. Great dislo- cations occur in South Wales, by which the Tremadoc, and even the Arenig rocks, are let down against the Harlech beds of the Longraynd group. For a more detailed account of the Avhole question of the discovery and the nomencla- [E. 9] m ■ m Ml 130 E. SPECIAL REPORT. T. STEKRY HUNT, 1875. ture of these older rocks, the reader is r(;ferred to the author's essay on The History of Canibrian and Silurian. (Chem. and Geol. Essays, pad in the Upper Graptolitic schists, 3,) to the superior poi'tion of the same series. The schists of division 3, in Sweden, include, according to Nicholson, two distinct graptolitic zones, the lower part containing the forms of the Ccmiston mndstones of Cum- bci'land, regarded as belonging to the Siluro-Cambrian; while the upper part yields the forms of the Coniston grits, the equivalents of the May-Hill sandstone, above the Bala group, and belonging to the true Silurian. This upjier por- tion, which constitutes the Ji/ih graptolitic zone, is well de- veloped in Norway. It would be foreign to the j^urposes of our history to enter into further details with regard to these higher graptolitic zones, whi(;h apparently correspond to those of the Utica and Clinton formations of North America. § 202. Returning now to the lower paleozoic rocks of the New York series, we have seen that Billings, conceiving that the Olenellus beds of Vermont and Newfoundland belong to a lower horizon than the typical Potsdam sandstone of New York, designated this as Upper Potsdam. This for- mation, as is w^ell known, is traced continuously from the southern base of the Adirondacks into tin? Ottawa basin in central Canada ; to the east and west of which it disappears along the northern outcrops of the paleozoic series. So far as yet observed, it rests in a nearly horizontal attitude upon the Eozoic crystalline rocks, and in Ilemmingford Moun- tain, near the north-west border of Lake (Jhamplain, where it reaches its greatest observed thickness, of about 600 feet, includes l)edsof a conglomerate holding jiebblcs of quartz, and others of green and blackish argillite. The rock is sometimes a friable sandstone, and at other times, a hard and almost vitreous quai'tzite, white, and rarely red in color. Towards the summit it becomes interstratified with dolo- ri GEOLOGICAL HISTORY OF SCOLITIIUS. E. 135 mitic layers, marking its passaije into the suceerdinu' Mag- nesian limestone, which, from its rough surface and its fee- ble (^ffervHsence with acids, was early misnamed the Calci- ferous sandrock. It is, howevei-, a true dolomite, granular in texture, and abounding in druses holding crystals of quartz, calcite, suli)hates of baryta and stroutia, and in some plac(^s small nodules of gypsum. Ft often passes to- wards the summit into an impure argillite, and has a maxi- mum thickness of 300 feet. § 203. The organic remains found in the Potsdam of the above defined area, are few in nuiubci" ; besides two species of Lingida, it has yielded at Keeseville, New York, a trilo- bite, at first called a Calymene,, but sul)sequently described by Bradley as Conoccpliardea {Conocoryphe) iiibiutus, which is associated with a species of Ht/olit/ics^ a Pleuroto- maria and ci-inoidal fragments. A species of DiJielloce- phalus lik<' D. Sesoslrif< is, according to Billings, met with in the superior beds of the Potsdam, at Whitehall, N(;w York, while at Beverley, Ontario, along with Liiiynhi acu- minata^ are found a Pleurotomaria^ an Opliileta, and two species of Orthoceras^ besides marks of alg{c. Billings, however, remarks that these beds should perhaps be in- cluded in the overlying Calciferous sandrock. In several localities in Canada, the beds of the Potsdam bear the tracks of large animals of several species, which have been named Protiahnifes and Climactlchnitcs, both of which are i-egarded as probably due to crustaceans. (Pal. Fossils, I, pages 57, 59, 97, 198.) § 264. In addition to these, the upper part of the forma- tion is found to be abundantly nmrked, over considerable surfaces, by a form descrilx'd by Billings under the name of Scolilkus Canadensis. ''This sx)ecies consists of cylindri- cal or irregular prismatic stems (or rather the cavities in the rock once occupied by such stems) from one to two lines in diameter, and from one to six inches in length, and eithr-r straight or more or less curved. In some specimens several of the stems are in contact with each other, and when this is the case, and the stems have an angular shape, they very much resemble the coral, Tetradhiin Tlie larger stems are VM E. SPECIAL UKPOltT. T. STEUUY HUNT, 1875. Nm more often straight than the; smaller. The individuals are usually scattered irregularly through the rock, lying in all diivctions." (Ibid., I, 00.) 'IMic l^i-olit/inti appears on the weathered surface of the l)e(ls "in the form of small holes, which sometimes pene- tnite vei'tically to a depth of several inches, but on break- ing up the rock they are found to be more or less cun'ed in (lill'crent directions, and often irregularly contorted, and in- termingled with eacli other. The casts of the interior of these cavities, in freshly broken or unweathered specimens of the rock, usually appear as cylindrical or angular rods, (with three, four or live sides,) composed ai)parently of grains of sand cemented by a slightly calcareous matter, more or less tinged with oxyd of iron. The origin of tliese holes is not quite certain ; some suppose them to be re- mains of fucoids, others of corals, while many are of opin- ion that tliey were the habitations of small burrowing ma- rine or shore-frequenting animals. Whatever may have been their origin, they characteriyx' only the upper part of tlie Potsdam sandstone. The original specimens, upon which the genus Scolithus was established, differ from those above described in being straight, and more decidedly cylindrical, and are therefore probably a distinct species.'' A ligure of Seollihun Canadensis is given in the Geology of Canada, page 102, from which the above account is quoted. § 20."). The name of H/iol/i/ius was proposed by S. S. llal- deman, in 1840, as the designation of a sub-genus of fuccjids, and was applied by liim to the cylindrical casts found in the Primal white sandstone at Chiques, on the Susquehanna. In 1847, Professor James Hall described ScoliUius linearis^ giving a ligure of one specimen from the J'usquehanna, of an- other from North Adams, Massachusetts, and of a third from a locality not named. It was said to be found vMfoly on Lake Champlain, but was refeiTed to the stone, and declared to occur in sandstones ■ base of the Green Mountains, as Pennsylvania, and Virginia. (Paleo. ilogy vol. I, pag(; 2, and plate I, ligs. 1 a — 1 c. § 2GG. Markings called Sculiihus^ have sin •w .S'ew md- the rsey, York, to been looked OEOUXilCAL HISTOUY OF SCOLITHUS. E. 137 [I. k II- Id upon as evidences of existence of tlie Pofsdani sandstone in various localities tlirouf;liout the Aiipalacliian valley, and in l*tMinsylvania were described by II. 1). Rofrm-s as character- istic of the Primal white sandstone, which wa;s regarded as the equivalent of the Potsdam, (§4, 7, 9.) The name of 7V huliles which, according to Rogers, was given to these mark- ings in the annual geological reports of Virginia and Penn- sylvania, was subsequently exchanged for tliatof Scollthufi linearis. The original description of this species by llall was amiilified and augmented by Rog^'rs, who describes it as "a nearly straight cylindrical simph.' stem-like impres- sion, nsually almost smooth, but in some specimens faintly waved or grooved transversely to its axis. Its diameter is from one eighth to one half an inch, its length from a few inches to two or three feet. Its position in the rock is in- variably perpendicular to the bedding, suggesting the idea of perforations by some marine worms. One end of the fos- sil always terminates at the upper surface of th(! bed of sand- stone inclosing it, and nsually in a rudely-llattened knob or head, giving to the whole the likeness of a large long pin. This knob is probably a cast formed in the wide, conical, funnel-shaped mouth of a cylindrical perforation. Similar stem-like forms occnr in some of the other sandstones of the liigher Apx)alachian fonnations, but none are so well char- acterized as this si)ecies of the Primal white sandstone. An excellent locality is at Chiques, on the Susquehanna." A figure is given by Rogers of this fossil, which is also said to occur in great abundance in the Blue Ridge of Virginia. (Geol. Penn., II, 815.) § 2G7. In isr)2, TIall described and figured, under the name of Scolilhus Terticalis, a form characterized as being smaller than S. linearis, and as penetrating vertically the beds of the ^Medina sandstone in Monroe county. New York. (Paleontology of New York, vol. II, page G, and plate II, figure 8.) It was not until 1862 that Billings described S. Canadensis, (§ 204,) at the same time declaring with re- gard to /S^. linearis, "it is generally larger, and the stems are straight and parallel with each other," and adding, "I have seen no specimens of this species m the Canadian 4 ilM. im I 138 E. SPECIAL KEPORT. T. STERRY HUNT, 1875. rocks, though it occurs in tlie lowest red sandstone of La- brador, on the strait of Bellisle."' Tliis sandstone, already noticed, (§ 215) is below the Olenellus limestone, and of the Srolii/ius therein found Billings elsewhere remarks, that "it (lillV^rs from the one so common in the Potsdam sandstone of Canada, in being larger and straighter. It is perfectly identical witii that of the Upper Primal sandstone of Penn- sylvania, and also with that of the Potsdam (Chilhowee) sandstone of Tennessee." (Pal. Fossils, III, 2, 96.) § 268. Several examples of ScoUthus which the present writer has examined from the Potsdam sandstone of Wis- consin, appear to be identical with aS*. Canadetisis and, though pi'obabl y distinct, are much more like to the L. verti- calls collected by him in the Medina (Levant) sandstone of Huntingdon county, Pennsylvania, than to the aS*. linearis found in the Primal white sandstone along the Susque- hanna and the Schuylkill. Some specimens from these lat- ter localities exhibit, in a marked manner, the transversely "waved or grooved" surface, noticed by Rogers, leading an eminent foreign geologist, who lately saw them for the iirst time, to take them foi' casts of crinoidal stems. § 269. Further investigations are however heeded to clear up the history of Scolii/n/s, and it would appear that even in the typical Potsdam sandstone there have been con- founded under this name the marks of distinct and unlike objects. The sandstone which at Port Henry, NV^w Yoi'k, forms the base of the Champlain series is, in its lower por- tions, a strong, hard, massive, thick-bedded, dark bluish or iron-gray quartzite, with lighter gray layers, and includes thin blackish shaly partings. The higher portions are thinner bedded, light-gray and porous, and are made up of strongly coherent rounded agglutinated grains, with irregular iut«M'sticPS. the wdiolc being silicious. and siighrly stained with inm-oxyd. Hall has noted the same structui'e in (he ujiper beds of the Potsdam in Iowa, and has well re- marked that their appearance suggests that they were "largely formed from silica in solution, or fi'om gelatinous silica." (Paleontology, Vol. Ill, page 4.) § 270. Some of these ux>per beds at Port Henry^ lately i '■^iul vr HISTORY OF THE CIIAZY FOKMATION. E. i;39 examined by the writer, abound in impressions evidently oro;anic, which have been designated S'coh'/kus. These appear iqjon the iq^per surface of the newly sei)arated beds as cylindrical cavities, each enclosing a centi-nl tube made up, like the surrounding rock, of coherent silicioiis griiins. These tubes are a millimeter in intei-nal diameter, with walls half a nuUimeter in diameter, and a vacant space of the same dimension between the tube and the smooth sur- rounding walls of the cavity; thougli vciy fragile, the in- terior tubes were disclosed in oblique fiactures of the rock to the length of a centimeter, without any marks of joints or Septa. They exhibited, in some cases, traces of two con- centric layers. The cylinders were seen to ti-a verse vertically the beds for distances of two oi' three inches, but the lower portions were tilled up and their internal structure was not aj^parent. The arrangement is such as would result from the enclosui'e in the rock of a cylinder having a centi'al axis, with an intermedia t'; space v/hich became tilled with silicious matter, the cylind -r, and its axis being subsequently re- moved. In weathered specimens, from which the internal rube lias disappeared, the cylindrical cavities, more or less completely filled, resemble very juuch the burrowings of a woi'm, l)ut in either condition they are evidently very distinct, l)oth from the ]irisinatic shapes not'ced by Billings under tlie name of Scolilhiis CamuUnsif^ (^'2(54, ) and tin* transversely grooved cylindrical rods of the Pfimal white sandstone. ^271. We have already seen that, while tli(» Potsdam sandstone graduates into the Calciferous sand-iock. the overlying Chazy foi-mation gives eviilence of a break in the succession of sediments; its base, in parts of the Ottawa basin, consisting of a limestone-conglomei'ate, resting on the Calciferous sand-i'ock. I'Jsewlx're in this region, it apjx-ars as a silicious conglomerate, with (iiiaitz {)ebl)les, nodnles of phosphate of lime, (coprolitesj and the characteristic fossils of the Chazy formation, resting directly on the Laurentian gneiss; while in Herkimer county. New \ u\k. the Chazy is absent from its place heiwt'en the Calciferous and the Trenton. At Grenville, on the Ottawa, there is found 140 E. SPECIAL REPORT. T. STERRY HUNT, 1875. above the limestone-conglomerate of the Chazy about fifty feet of grayish sandstone, sometimes ripple-marked, and occasionally conglomerate. These are accompanied and fol- lowed by greenish fucoidal shales, above which, making the npper portion of the Chazy formation, is a reddisli or gray- ish jiure massive limestone, composed, in great part, of the crystalline remains of crinoids and cj^stideans, while other beds abound in brachiopods. These limestones, which are sometimes interstratified with dolomitic layers, have at Mon- treal, where they are largely quarried for l^uilding-purposes, a thickness of seventy feet, the aggregate of the whole Chazy formation in the region being about IHO feet. • § 272. The Chazy, after disappearing beneath the border of the Trenton, a little to the north-east of Montreal, (§ 244,) re-appears oOO miles further on in the same direction, on the Mingtui Islands in the gulf of St. Lawrence, where it is rep- resented by a series of fossil iferous limestones, witli some interposed sandstones and shales, the whole thickness being estimated at about 300 feet. The underlying beds, supposed to represent the Calcii'erous sand- rock, are also highly fos- siliferous magnesian limestones, of which about 250 feet have been observed. (Geology of Canada, chapters VII nnd VIII.) § 2?;}. In the northern part of Lake Huron, horizontal liiiiestones, dolomitic at the base, and fossiliferous through- out, are L'ouud resting, at the Snake Islands, ou the up- turned Iluronian strata, while at Lacloche Island, and fur- ther to the west, similar limestones repose ui)on hoi-izontal beds of red and white sandstone, known as the St. Mary's sandstone. These limestones have yielded the organic re- mains of the Birdseye, Black lliver, and Trenton divisions of the Trenton grou)), and in Sugar Island, according to Professor Hall, have at their base some arenaceous and argillaceous beds, which contain the chai'acteristic fossils of the Chazy formation. (Foster and Whitney, Geology of Lake Superior, II, 140.) § 274. To tlu' south-west of Lake Superior, In Wisconsin, Minnesota and Iowa, in the upper Mississippi valley, we find i'ep<...e(l, with some variations, the rocks of tluKMiam- CAMBRIAN OF THE MISSISSIPPI VALLEY. E. 141 I I I t5 ital llp- u I'- ll :i] •y's OllS to 111(1 dls in, we Ill- plain division of the New York series. These rocks iiave been studied bv David J). Owen, bv James Hall, and later by lloland Irving. In Wisconsin, where these strata occu- py a large area to the west and south of tlie crystalline rocks, the Potsdam sandstone is desciil)ed as liaving a maximum tliickness of about 700 feet, and as overlaid by the Lower Magnesian limestone of Owen. It however thins out to tlie northward, where the limestone rests directlv on the crystalline strata. It was noticed by Hall that tlie up- per part of the Potsdam becomes dolomitic, showing a pass- age to the overlying formation, and this transition lias since been studied by Irving, in Dane and Columbia counties. He describes there 800 feet of sandstone, which have been penetrated in borings, and sliow more or less dolomitic ad- mixture for the upper two thirds. Above this lie about thirty feet of a yellowish magnesian limestone, massive be- low and shaly above. It includes layers of green-sand, especially near its base, and in places abounds in trilobites, tlie most common of which is DikeUoccjjJialn.s J///ni(,sofrn- sis. Tliis division, called by Irving the Mendota limestone, is succeeded by tliirty-hve feet of sandstone, often purely silicious, but sometimes ferruginous and dolomitic. To this division, wliich extends over wide areas, the name of the Madison sandstone is given. Above this occurs the main body of tlie Lower Magnesian limestone, from eighty to li?0 feet in thickness, including, at its base, a persistent stratum of oolitic silicious rock, and layers of green-sand, and con- sisting above chiefly of cherty dolomite. Tliis, which is sometimes geodiferous, contains small quantities of lead ore, and very few organic remains. The glauconite or green-sand from tliese ancient rocks closely resembles that from the cretaceous strata of New Jersey. An analysis, by the writer, of a siH'cimen collected by Professor Hall at Red Bird in Minnesota, gave silica, 44.58 ; protoxyd of iron, 20.01 ; magnesia, 1.27 ; lime, 2.4!) ; alumina, 11.45; potash, G.9G; soda, 0.98; Avater, 9.00 = 100.00. (Report of Geological Survey of Canada, 180:3-00, page 232.) § 275. The Lower Magnesian limestone is directly overlaid ^s* m v. 142 E. SPECIAL REPORT. T. STEKRY HUNT, 1875. by the St. Peter's sandstone of Owen. This is a white, yel- lowish, or reddish friable sandstone, wliich attains a thick- ness of 120 feet in the southern part of the state, but else- where thins out and disapjiears. It has yielded no organic remains, except fucoidal markings, and is directly overlaid by the Trenton limestone group. This is by Hall divided into three parts, a lower division of bulf -colored dolomite, al)out twenty feet in thickness, holding the fossils of the Birdseye and Black River lime- stones of New York ; a middle part, of about 100 feet of blue limestone, carrying the organic remains of the Trenton proper ; and an upper part, the Galena limestone — the Up- per Magnesian limestone of Owen — a porous dolomite, abounding in lead ore, and attaining a thickness of 2o0 feet. Above this are from 200 to 400 feet of thin-bedded lime- stones, shales, and clays, the rei)resentaiives of the Utica and Loraine shales of the east, designated in the west the Cincinnati group. § 276. The most significant fact about the St. Peter's sand- stone is that, according to Hall, it is clearly separated alike from the formations below and above, the transition at both horizons being "abrupt and without altei-nation or admixture of material." Irving has further notified that it fills up eroded hollows in the Lower Magnesian limestone, (which is regarded as the representative of the Calciferous sandrock,) being abruptly succeeded by the limestones of the Trenton group. The St. Peter's sandstone thus occu- pies the x^osilion of the Chazy formation, which, as has been already set forth, (§ 242, 243,) shows in the eastern region a break both paleontological and stratigraphical, alike at its base and its summit, and in the Ottawa basin is in part a detrital rock. This intermediate sandstone in Wisconsin was consequently designated by Hall as the Chazy sand- stone, (Geol. of Wisconsin, 18G2 ; Irving, Anier. Jour. Science, [L^' vol. IX, page 440.) § 277. It ^as in the lower sandstones of Wisc^onsin, Min- nesota, and Iowa, tliat D. D. Owen discovered the remarka- ble triK)bitic fauna, associated with numerous brachiopods and with fragments of crinoidal stems, whicliwas described CAMBRIAN OF THE MISSISSIPPI VALLEY. E. 143 111- ka- led by him in 1852. Hal), who reexamined the strata and re- vised the fauna in 186^, distinguished three paleontological stages. Of these, the lower affords only Conocoryphe, with Theca and some linguloid shells. The middle stage con- tains Arlonellus, Agnosius, Flijchaspis, certain species of Dikellocephalus^ and of Conocoryj)he, to which Hall referred some forms hitherto included in the preceding genus. With this middle stage is also found a grai)tolite, Dendrograptus Halllanus. The third or upper stfige, declared by Hall to be clearly separated from the last, and from 400 to 500 feet above the lower stage, affords no species of Conocoryphe, but is marked by the large and characteristic species of Dikrl- locephalus, D.Minnesotensls^ and D. Peprnensis, described as passing up into the Lower Magnesian limestone, (Ifith Appendix to Regents' Report, 180:j, pages 120, 183.) This third stage is believed by Irving to correspond to the Men- dota limestone. § 278. This series of about 1,000 feet of sedimentary strata below the St. Peter's or Chazy sandstone of Wisconsin, is thus shown by the studies of Hall, to include in its several faunas representatives of genera of trilol)ites found in both the Lower and Upper Cambrian of Great Britain, and in those sub-divisions of the ILidson-River group or Upper Taconic to which the names of Lower Potsdam and Levis have been given. The corresponding series of strata, con- sisting of alternations of sandstone and magnesian lime- stone, attains a still greater thickness in Missouri. TIk- Artesian well at St. Louis passed through 2,480 feet of such strata between the base of tlie Trenton and the lloor of crystalline granitoid rocks beneath. That the tyijical Pots- dam sandstone of northei'u New York and central ('anada, with its few organic remains, is represented somewhere in the western series, cannot be doubted, but until its fauna is better knoAvn, it will not be possibl*- to fix its precise horizon. It will probably be found desirable, on further study, to revise the nomenclature oii these lowest paleo- zoic rocks in Americja, and to establish new sub-divisions, as in Europe. § 271). In conformity with the genenil principle regulating 144 E. SPECIAL REPOllT. T. STEUKY HUNT, 1875. the: distribution of sediments over the great American paleo- zoic basin, we iind little or nothing in tlie silicious and dolo- mitic Cambi'ian strata of the Mississippi valley resembling the Ui)per Taconic conglomerates, sandstojies and aigillites of the eastern border of the basin. It is proper, in this con- nection, to call attention to some important j^oints in the history of tliese latter rocks, and their relation to the Silnro- Cambrian strata, which have been omitted in the preceding cha])t('rs, tliongh referred to in a foot-note on page 127. § 280. In the lirst annual report on the geology of the central district of New York, the strata al)ove the Calcifer- ons san(h'()ck were described by Conrad as consisting of the fossil if erous limestones of Trenton F,,Ils, overlaid by dark shales, to which sncceed a series of fossil iferons lead- colored shales, alternating with gray sandstones, well dis- j)layed at and near Pulaski, (m tlie Salmon l?iver, in Oswe- go county. At the summit oi' these was a bed of sandst(me quarried for grindstones, and in Oneida county the series was overlaid by a qnart/.ose conglomerate. Vjinuxem, \vho succeeded Conrad in the examination of the distiict the next year, gave to the Salmon lliver strata the name of the Pulaski shales and sandstones. These coirespond to the Loraiue shales, (named from Loraine, in Jefferson county,) and the Gray sandstone of Emmons, which were then sui> posed by the latter to be the equivalents of the Argillite and Oraywacke series described by Mather, in his fourth annual report on the southern district of New York, by the names of the Hudson slate group, or the Hudson Rive^' slates, (§ 02, 04.) The counties of Jefferson and Lewis, in (he northern dlstri<'t examined by Emmons, were connected with tlu; Hudson valley through the central district, which eml)i'aced the counties of Oswego, Oneida, Herkimer, and Montgomery, extending southeastward along the Mohawk valley. ^ 2S1. The rocks of this distiict were now described by A'anuxem, under the name of the Hudson-River group, and according to him, included two entirely distinct divisions, the u])])*'!' a liighly fossiliferous series, the Pulaski shales and sandstones, found west of the Adirondacks in Jefferson, J VANUXEM OX THE IIUDSON-Iil VEll GliOUP. E. 140 tlie Lv,) ip- ite nth tlie ive^' in •ted licli iiid i>y Illd ins, lies on. Lewis and Oswego counties, and disappearing- to the soutli- eastwai'd in Oneida county. These are the lead-coh)i'e(l shales and sandstones of Conrad. The h>wer member of the Hudson lliver group, as deiined by Yanuxem, was nanu^l tlie Fra'nlvfort division, from Fraidvfort, in Herkimer coun- ty, and was described as consisting of greenish aigillites and sandstones, which underlie the Pulaski shales to the noitliwest, as far as Jelferson county, constitute in Ilerkimei" and Montgomeiy the only rei)resentative of the Hudson- River group, and extend eastward, through Schenectady, Alban}', and Saratoga counties, to the Hudson river. Tins lower division was said to yield none of the organic renuiins of the Pulaski division, ))Ut to include some grai)tolitic shales. To the Frankfort slates and sandstoniis, it was suggested by Yanuxem, might belong the thick nnisses of argillaceous strata of "controverted age," (the Tacojuc of Emmons) along the Hudson valley. J$ 282. Yanuxem, while he thus attempted to connect the argillaceous strata of the northwestern counties with those of the Hudson valley, spoke of " the diiliculty of separating or distinguishing the slaty or schistose members of the (Hud- son River) group from those of greater age, with wiiich on their eastern border the two {■sic) are, more or less, n-ally or ai)[)arently blended." The force of this observation is more clearly apparent to-day, when it is known that thelaiger2)art of these schistose rocks of the Huds(m River valley are of much great<'r antiquity than the Pulaski, (Loraine) and Ftica slates, and must be assigned a jiosition below instead of above the Trenton limestones. A'anuxcm further remaiks, that tln^ two divisions of the Hudson River gi'oup, as ddiucd by him, exist separati'ly in Pennsylvania. The Pulaski slates, having in all respects, the same characters as in New York, are declared to occur in the Nippenose valley, west of the Susquehanna, while the i'^'ankfort slates and sandstones a])pear to the east of the North Mountain, in the Kittatinny valley, and include the rooting-slates of the Delaware. These latter are placed by Emnu)ns at the summit of the Lower Taconic, but were by Rogers included, with the fossiliferous shales of Nix)pe- [E. 10] 'HI 140 E. SPECIAL liEPOUT. T. STEUllY HUNT, 1875. nose and Kisliacoquillas valleys, in tlie upper portion of his Matinal division. § 283. It is important to note in this place, that, accord- ing to V^anuxem, tlie Oneida conglomerate, the admitted representative of the conglomerate and sandstone of the North Mountain in Pennsylvania, rests in Oneida county. New York, upon the Pulaski shales, (sometimes with the intervention of the Gray band, which was by Emmons united with the Oneida,) while in Herkimer county this conglom- erate overlies directly tlie Frankfort shales and sandstones. § 284. In connection with tlie disappearance of the Pu- laski or Loraine shales to the southeastward in the Mohawk valley, we may note the simihir disappearance of the Tren- ton limestones. These, in Canada, have been found at jioints as widely remote as Quebec, Montreal, Ottawa, the Bay of Quintd, Lake Simcoe, and the shores of Lake Huron, to have a thickness of from 600 to 7o0 feet, being everywhere followed by the Utioii slates and Loraine shales, with a united volume of fi'om 800 to 1,100 feet or more. The thickness of the Trenton limestones in the northern part of Lewis coun- ty. New York, is, however, but 800 feet. This is reduced to 100 feet at Trenton Falls, and to thirty feet in the Mo- hawk valley, while south of the Mohawk the limestone is seldom over ten fee*", and, according to Conrad, thins out and wholly disappears to the southeast. He tdso notes that the gray sparry fossiliferous beds, which, in Oneida county, he distinguislied as a separate and lower division of the Trenton group, grow thin, and disai)pear to the eastward along the line of the canal, in Montgomery county. I^'or the statements in the preceeding sections, beginning with § 280, see the Geology of the Third District of New York, and also the previous annual reports of Conrad and Vanuxem on the district, passim. The facts should be con- sidered in comiection with the statements in § 245 with regard to the relations of the Trenton audits overlying argillaceous strata to inferior rocks, with those of Emmons in ,^ 07, 98, and with the earlier statements of Eaton, cited in § 50. We shall return to the consideration of the questions here raised in a subsequent chapter. CHAPTER V. niSTOKICAL SKETCH CONTINUED. US (I lU a § 284. We have in chapters II and III discussed tlie his- tory of the crystalline stratified rocks of eastern North America, up to the year 1855, at which date the names of Laurentian and Huronian had already been applied to two divisions of these rocks (§ 144), which had been described and defined by the geological survey of Canada as more an- cient than the base of the Xew York paleozoic series. Tli j officers of that survey Jiad then adopted, so far as regards the crystalline strata of the Atlantic belt (with the excep- tion of the Laurentian) the view held by Mather, that these rocks were the altered equivalents of the Champlain divis- ion of that series, and consequently more recent than the Laurentian or the Huronian (§ lGO-174). We shall now proceed to discuss successively the progress since made in our knowledge of the Laurentian and its divisions, of the newer crystalline schists of the Atlantic belt, and of the Vol- canic formations around Lake Supeiior (§ 137). 148 E. SPECIAL KKPOHT. T. STERRY HUNT, 1875. iii § 285. The so-called Metanioiphic pjneissic series to which, in 1854, the name of Laurentian was given had, as already shown, been l)y Logan, from his observations on the Ottawa river in 1845, divided into two groups, the upper one, with its intercalated bands of crystalline limestone, being regarded as a sei)arate overlying formation ; (§ 13;]; a distin(;- tion which is well founded, but has generally been disre- garded in subsequent descriptions of these rocks. In 1847 the present writer spent some time in the examination of the crystalline limestones of this series, and their associated rocks, as seen at various localities along the vjdley of the Ottawa, as far as Poi-tagc; du Fort, and in the vicinity of Perth, Ontario. The observations then made were given in the report of the survey of 1847, (pages 125-138) and the results of chemical analyses of the materials collected at that time, in the report of 1850 (pages 35-46). § 286. In 1850, Mr. Alexander Murray, in company with the writer, examined these same rocks to the north of the Thousand Islands. The observations then made will be found in Murray's report of 1851 (pages 59-04). The most important fact there announced was the occurrence of a bed of silicious conglomerate, found in the township of Bastard, intercalated in the crystalline I'mestones of the series, which here dip N. 55° E. < 30°. The limestone layers, both above and below, are white, coarsely crystalline, graphitic and micaceous, while the overlying one contains clion- drodite. The included conglomerate layer, eighteen inches in thickness, is a finely granular sandstone, including large and small well-defined pebbles of vitreous quartz, and others which could only be described as a laminated sandstone. Pebbles and rounded grains of feldspar, together with scales of mica and of graphite were also found in the matrix. It is not imjirobable that this .'uique occurrence may be due to a dislocation, followed by movements of the strata, l)y which a more recent conglomerate has become enclosed in the ancient limestones. § 287. It was not until 1853 and 1854, that the difficult task of unraveling the structure of these ancient rocks was undertaken by Logan. The first results of his labors HISTORY OF LABUADOUITE ROCKS. E. 149 lult lors therein were set forth in the little essay called an Esquisse Geologique diu Canada^ published at Paris in ISOa (?} 144), but f urf lier researches were made by him in ISfM), and his con- clusions are given with some detail in tlie report for isr^lj-nc, (pages 7-52) published in 1857 ; — which wasacconii)anied by a map showing the geographical distribution of the Lauren- tian limestones in the counties of Argenteuil and Terrebonne, a little north and west of Montreal. In this report was shown the existence of one or more great bands of crystal- line limestone, interstratilied with the gneisses and accom- panied by considerable masses of quartzite and of mag- netite, tlie whole being greatly folded, and intersected by numerous masses of eruptive rocks. § 288. The rock already recognized by Emmons under the name of hypersthene-rock or labradorite-rock, in tlie Adi- rondacks (§ 88) was also found in the region in question. Rolled masses of it liad long been known in the valley of the St. Lawrence, and the rock had been observed in place by Dr. Bigsby, on the northeast shore of Lake Huron, where it was described as occupying a breadth of live miles. (Amer. Jour. Science, I, viii, GO). In 1852 Logan found a considerable area of the rock in Mille-Isles, Morin and Abercrombie, in the county of Terrebonne, and a speci- men of it was described by the writer in some detail, with analyses, in the report for 1852, (page 107) and shown to consist of cleavable lavender-blue labradorite, in a greenish base composed chietly of the same feldspar with 4.8 per cent, of carbonate of lime and a little magnetite. § 289. In the following year the writer examined the rocks of this region in company with Logan, and subsequently extended his observations to several other points. The first results of these examinations are given in Logan's report for 1853-5G (pau'es 35-37,) and inasmuch as the rocks in ques- tion have since assumed a considerable geological import- ance it is thought best to rei)rint therefrom the following extracts, defining their lithological characters. (§ 132.) § 290. The rocks are described in general terms as "chiefly compos "■ of lime-feldspar, varying in composition between labradorite iind andesine, and are marked by the presence 150 E. SPECIAL REPORT. T. STERRY HUNT, 1875. ■; I m HI! of hypersthene and iliiienite." Of one locality .idjoining the crystalline limestone in Mille-Lsles it was said, " the rock is chieHy labnidoritc, and consists of a tine-grained paste of tliis mineral, of a puri)lish-grey, weathering to an opaque white, and holding cleavable forms of a lavender-blue feld- spar, several inches in diameter. Many of these exhil)it a fine golden-green and deej) blue opalescence, and the same hues occasionally emanate from minute j^oints in the paste. The rock is generally massive, and it is occasionally very difficult to find any indication of those parallel planes which are so generally present in common gneiss. The large cleav- able forms of labradorite, however, as well as the hyper- sthene and ilmenite, are found to prevail in belts that ap- pear to be parallel to one anothei', and garnetifei-ous or mi- caceous l)ands occasionally indicate the same arrangement." § 291. At St. Jerome, on the east side of Rividrt} du Nord, a rock belonging to the same area as that last mentioned was described as gneissic in structure. " Darkei' and lighter bands run parallel to one another, the shades being occa- sioned by the greater or less abundance of a line-grained greenish lime-feldspar, weathering ojjaque white, which oc- curs in spots, surrounded by a darker colored network, consisting of a dark green pyroxene and magnetic iron ore, with small disseminated clusters of yellowish-red garnets. In this mass, large and small individuals of labradorite, some of them two or three inches in diameter, are irregu- larly disseminated, and irregular veins or apjiarent segre- gations occur here and there, composed of flesh-red oitho- clase and translucent colorless quartz." § 292. "On the west side of the river, rock of a similar character is met with, but there is seen also an interstratified mass of reddish hornblendic gneiss, the feldspar of which is orthoclase. The breadth of the mass of gneiss is two hun- dred yards, and it is marked by beds darker than other parts from the presence of hornblende. * * On the west side of this mass of gneiss smaller bands of a similar nature seemed to alternate with those containing lime-feld- spar. Beds of quartz were also interstratitied. and some of these were in one place so loaded with small garnets as to ■■«!' HISTOIIY OF LABKADORITE ROCKS. E. 151 lar 5ed ch 11 n- lier Ihe ar d- of Ito form a fine granular garnet-rook. '■• * LiniH-fcldsparrock, more resembling that of Monn in its opaque white massive asjiert, was mot with at New (Jlasgow, on tho Aohigan, in Terrebonne seigniory; tho stratiliration, howevor, was well marked by bands of garnets and pyroxono, and by alter- nations of the rock, on the west side, with common gneiss." Similar rocks, belonging to the same area, were examined further to the northeast in Rawdon, and in Chertsey, in the county of Leinster. ^ 2!):?. Th(> materials collected in the localities above men- tioned, and also in another area, in Chateau llichor in the county of Montmorenci, were subsequently submitted to a chemical and lithological examination by the writer, and described in the report for 1853-50 (pages 373-i3S;3) as belonging to crystalline strata closely associated with the limestones, gneisses and quartzites of the Laurentian series. Of tho rocks in question it was said : " They are comi)osed chiefly of feldspar, with small portions of black mica, green pyroxene, and occasionally epidote, garnet and quartz ; i)or- tions of hypersthene are also frequently present, and hence the New York geologists have designated these essentially feldspathic strata by tho name of hyporsthene-rock. In addition to the minerals just mentioned, we may add ilnion- ite or titaniferous iron, which occurs sometimes in large masses, and at other times in small disseminated grains, which, like the hypersthene, appear to mark the planes of stratilication. If to these we add small portions of iron i)y- rites, and a little disseminated carlxmate of lime, we shall have the mineralogy of these rocks, so far as yet known." "The texture of these feldspar rocks is varied ; sometimes the mass is a confusedly crystalline aggregate, exhibiting cleavage-surfaces three or four inches in diameter, with a finegrained somewhat calcareous jwste in the interstices. Sometimes the whole rock is uniformlj'' granular, whih? more frequently a granular base holds, at intervals, cleavable masses of feldspar, often several inches in diameter. The colors of these rocks vai-y from grayish and bluish- white, to lavender and violet-blue; flesh-red, greenish and bi'own- ish tints are also met with ; the colors are rarely brilliant. 152 E. SPIOCIAL KEPOKT. T. STKRRY HUNT, 1875. These feldspars seldom occur in distinct crystals, but their cleavage is triclinic, a fact which taken in conn(?ction with the densities, varying from 2.00 to 2.73, shows them to be- long to the group of which albite and ancn'thite may l)o taken as the rejiresentatives. The bluish cleavable varieties often exhibit the opalesence of labradorite, to which species American mineralogists have hitherto referred them ; but with th(i exception of a few analyses by myself, we have had as yet no published chemical examinations of any of these feldspars. My investigations show that while all of them are feldspars with a base of lime and soda, the com- position varies very much, being sometimes that of labra- dorite, andesine, or intermediute varieties, and at other times approaching to that of anorthite." § 294. Of the lime-feldspar rocks of the county of Lein- ster it was then said : "In tiie townships of Rawdon and Chertsey, they are often fine-grained and homogeneous, and constitute an exceedingly tough I'ock, with an uneven sub- conchoidal fi'actur(% and a l'eel)ly vitreous lustre ; this va- riety is bluish or grayish-white in color, somewhat translu- cent, and exliil)its here and there the cleavage of grains of feldspar. Great masses of this rock are almost free from foreign minerals, while other portions abound in a green granular pyroxene, arranged in thin, interrupted i)arallel layers, with ilmenite. These layers of pyroxene are seldom more than four or live lines in thickness, and occur an inch or two apart, while the layers of the ilmenite are still thin- ner, and often enclosed in those of the pyroxene, idcmg the limits of which deep-red grains of garnet are occasionally seen. These different minerals appear in lelief on the white weathered surface of the rock, and give a picture of its stratified structure, which however is not less apparent on the surfaces of recent fracture. Small rounded l)luish masses of cleavabh^ feldspar are frecxueiifly diss'ininated in the same planes as the other minerals. 1-. some in- stances the pyroxene appears to graduate into, and to be rei>laced liy, foliated hypersthene." ^ 29j. Of the i ime-feldspar rocks of Chateau Richer, it was said : " They cover a breadth of two or three miles across S «f' nibiORY OF LABUADOUITE ROCKS, E. 153 the strike, bounded by crystalline limestone on one side, and a qnartzo-feldspatlii(^ rock on the other, and risin-j; into small hills. In this area there oeciir several varieties of the rock, but the most interestinij; is the one made up of a line granular base, greenish or grayish-white in color, holding masses of a reddish cleavable feldspar, wliich are sometimes from one tenth to one half an inch in diameter, but often take the form of large imperfect crystals, frequently twelve inches long and four or live inches wide. These dimen- sions correspond to the faces M and T, while the face P, characteriztnl ])y its jierfect cleavage, is from half an inch to tw^o inclies broad. Twin crystals sometimes occur, having a composition parallel to M," "Ilypersthene is met with throughout the rock in flat- tened masses, which, although variable and irregular in their disfribution, exhibit a general parallelism ; they are occasionally four or five inches in breadth, by an inch or more in tliickness, and are separated fnuu thegranulai- I'elds- patliic base by a thin lilm c;f bi'ownish-black mica. Titan- iferous iron ore is also found in the rock in grains and len- ticular masses, occasionally an inch or two in thickness ; these occur in the granular base, and generally near the hy- persthene, but grains of the ore are occasionally found in the crystalline feldsjvir. [which is andesine]. Quartz, in small grains, is imbedded in the titaniferous iron ore, but was not observed elsewhere in the rock." § 2DG. The report already cited gave fourteen analyses of of these feldspathic rocks, including both the cleavable feldspars and the surrounding paste, and showing a varia- tion in the amount of silica from 47.40 to 59.80 percent., and in the lime from 7.73 to 14. "Jt per cent., thie propoi'tion of alkaM (chic^tly soda) generally decreasing as that ol' the lime augmented ; v. Idle the specill(^ gravity varied from 2A)7 to 2.7.'?. The analyses of all these feldsi)ars, as W(dl of the accompanying hypersthene and ilmenite, will be found under their respective heads in th(i Geology of Canada, where, on page 590, is given the mean composition of the felds])ars, as d<'du<'ed from many analyses. For the views at that time put forth as to the constitution of these feld- fi! ■i IM E. SPECIAL REPORT. T. STKP.RY JUJNT, 1875. til I; i ;:i M! sjuirs, the reader is referred to the uiithor's paper in the L. E. and D. Pliilosophical Magazine for May, ISi'iS, and to his Chemical and Geological Essays, page 448. § 297. The report of the surrey for JC58 (publislied in 1859) contains the results of further explorations by Sir William Logan, and his assistant Mr. James Lowe, in the Laurentian region already referred to, northwest of Mon- treal, during the years 1857 and 1858. An attempt was therein made to fix the succession and thickness of the gneissic and limestone series, and the conclusions then anncmnced were confirmed by the labors of the following three years. The ''Geology of Canada,'" a volume of 983 pages octavo, published in 18013, was in great part printed in 18G2, and the first twenty chapters rej)resented the state of our knowledge of the rocks in question at the close of 18(51. Chapter XXII however gave the fui'ther results of the field-work of 18(52. This volume was accompanied by an Atlas with exphuiatory text, which contained a colored geological map, showing the distribution of the Laurentian limestones in the counties of Ottawa. Terrebonne, Argen- teuil and Two-Mountains. The breadth of the region thus mapped (on a scale of seven miles to the incli) was about fifty miles from east to west, and its greatest length about the same. The sharply folded, and ofter inverted strata have a strike about ten degrees east of north. § 208. The succession in this region, as now described by Logan, was as follows in ascending- order from a great underlying m.ass of gneiss, which niaives the Trembling Mountain in Grandison, and is <)wn. B. I'irst or Troinl)ling-Lako Limestone band. . . . 1,500 foot. C. Sooond Orthocliiso Otiol.ss 4,000 foot. D. Second or fJroor-Lalio Limostono band, includ- ing t... subnrdiiijitc l);iii!l.s dT garnotiibroiis qiiartKitc; and liornbh'ndic gi:ois.s, nialvinff up aljont one lialftlio volume 2,500 feet. DIVISIONS IN THE LAURENTIAN SERIES. E. 155 E. Third Orthoclaso GnoLss — including several bands of garnetiferous gneiss and quurtzito in tlio lower, and nnicli coarsely porphyrltic gneiss in the upper part 3,500 feet. F. Third or Grenville Limestone band, said to vary in thiclcncss from 00 to l,r)00 feet, luiving in some parts an interstratified band of gneiss, and estimated at 750 feet. G. Fourth Orthoclaso Gneiss including, besides a tliin l)ed of limestone, a band of fiOO feet of quartzite 5,000 feet. 17,1250 feet. § 299. The collective ime of the Grenville series was subsequently applied to the whole succession from the base of the limestone B. to the summit of the gneiss G. (Geology of Canada, page 839). This corresponds to the upper group in the Laurentian series, originally indicated by Logan in 1845, (§ 133) while the great underlying mass of granitoid gneiss, A., of unknown thickness, which is largely developed in the county of Ottawa, and may be called the Ottawa Gneiss, is the lower group. § 300. The name of orthoclase-gneiss was used to desig- nate the feldspathic rocks of the Ottawa and Grenville divis- ions, becaus(' the feldspar belongs chielly to the species orthoclase, although, as was then pointed out : "Small por- tions of a white triclinic feldspar, which is api3arently olig- oclase or albite, are occasionally found with the reddish orthoclase of the coarser gneiss." It was further shown, however, that a tine-grained reddish gneiss from Grenville, in which orthoclase was apparently the predominant min- eral, contained nearly as much soda as i)otash (Ibid, 587). To distinguish from these qiiart/o-feldspatljic rocks the more basic gneissoid roi^ks, consisting cliieliy of lime-l'eld- spars. anorthic in crystallization, (for which Delesse liad ])i'oposed the general term of anorthose) the name of anorthosite rocks, or anortholites, was at this time suggest<'d for the latter . § 301 . It was then the opinion of the present writer, as ex- 16G E. SPECIAL REPORT. T. STEKllY HUNT, 1S75. ^wH! pressed in ISGl, that "future investigations may furnish evi- dence which will divide the Laurentian series into several formations, distinguished by want of conformity and by mineralogical diiferences." (Ibid, page 580). This exx)ecta- tion was soon fulfilled. In chapter III of the GeoL^gy, from which the above section is condensed, a fourth limestone ^"^d, that of Morin, is mentioned as probably occupying a position above the fourth gneiss, Gr., and as followed by the great mass of anorthosite rocks which, with a genei'ally high westward dip, occupy an area at least twelve miles in breadth, to the north and east ol" the region mappetl. To tliese rocks was jirovisionally assigned a volume of 10,000 feet, but it was exj^ressly said that "the thickness is wholly conjectural." § 802. The explorations of 18G2 added materially to our knowledge of the relations of these anorthosite rocks. Ly- ing apart, and to the west of the great area in the counties of Terrebonne and Leinster, there was discovered in Sala- berry, a smaller portion of anortholite, beneath which one of the limestone bands of the Grenville series appeared to pass. It was also found that the Morin limestone band, (supposed to be a repetition of one of those named in the section) disappears in like manner beneath the southwest edge of the great anortholitearcui. From these facts it was considered "probable that tin? anorthosite rock overlies the whole Grenville series uncouformably, and that the mass of it on the west side of Sahd)erry is an outlying portion," giving reason to suppose "the existence in the Laurentiiin system of two immense sedimentarv formations, thf* one sup- erimposed unconformal)ly upon the other, witli probal)ly a great diireronce in lime betwf^en them." In confirmation of what had been i)reviously assorted as to its lithologi- cal character, it wa,-! further said; "This new formation, altho^^gh characterized by a predonunance of anortholites, appear to contain in some parts interstratilied beds of ortlio- clase-gneiss, cpiartzites and limestones, all of which are found associated with it near New Glasgow" (Ibid, pageSIW). ^ 'AO',]. In the originnl (h'scription, the FourHi Orihoclase Gneiss, G. of the section, was s:iid to be intorstratilied in HISTORY OF LABRADORITE ROCKS. E. 157 g-1- its upper part with anortholites (§ 202) and was rpuarded as sliou'ing" a passage from the gneisses below into tlie an- ortliolites above. Since however this ni)per series elsewhere includes layers of orthoclase-gneiss and quartzite, not nn- like those fonnd in the Grenville series, it is probable that these supposed beds of passage are refdly a portion of the newer formation. It was both on acconnt of this association, and of the gneiss-like structure of the anortholites themselves, that this overlying series way designated, alike in the text of the Atlas, and on the map pul)lished in ISO."), by the name of Anorthosite Gneiss. This was then called Upper Lauren- tian or Labradorian, the name of Lower Laurentian being reserved for the gneisses, quartzites, and limestcmes of the Grenville series, and tlie underlying Ottawa Gneiss. § ;]04. The further liistory of these labradorite or anor- thosite rocks may here be told. Besides the localities already mentioned, near Montreal and near Quebec, they are found at many places within the Laurentian region (m the north side of the lower St. Lawrence. They ai-e known in the parish of St. Trbain, near Bay St. Paul, jind over a large area on the Saguenay, between Chicoutiini and Lake St. John. A description of the labradorite rocks of this latter district, as observed and collected by Mr. James Rich- ardson in 1857, will be found in the rei')ort for that year (pages 79 — 84.) Many beautiful varieties are there met with, and the stratification, which is well marked, sometimes shows inchided b:inds of orthoclase gneiss, and in one locality a layer of pak,' green i^yrallolite (renssellaerite.) In some instances the blue granitoid labradoi-ite rock con- tains distinct grains of vitreous quartz, which is however comparatively rare. Similar rocks are found at many points along the north-west shore of the Gulf of St. Lawrence, from the Saguenay as far as Labrador. Tiiey are well seen at the mouth of the Pentecost river, about IGO miles below the mouth of the Saguenay, and on the Bay of Seven Islands, some forty miles further. This locality is probably connected with the lai-ge extent of similar rocks, observed by Prof. Hind to form a chain of If ■ IH 158 E. SPECIAL REPORT. T. STEKRY HUNT, 1875. Wii! hills along the River Moisie. Labradorite rocks were also observed by Bayfield to occupy the coast for several miles, near Mingan. In each of these localities, these rocks appear to be in contact only with the Laurentian gneiss, except in the area near Montreal, where their southern border is un- conformably overlaid by the Potsdam sandstone of the St. Lawrence valley. § 305. The rocks are widely spread on the coast of Lab- rador, wliere their characteristic feldspar was first found, and whence it takes its name. Prof. A. S. Packard, Jr., has described some of the localities in this region, where he found considerable areas of anortholite surrounded by gneiss, and obsei'ved bosses or domes of it resting ujion stratified quartzose, horublendic and feldspathic rocks, in such a manner as to lead him to suppose the anortholites to be eruptive, (Mem. Bost. Soc. Nat. Hist. Vol. I, part ii, pp. 214-217.) Labradorite rocks were long since observed by Jukes in the western part of Newfoundland, and Mr. Alex. Murray, in his geological map of the island, pub- lished in 1870, has shown, besides several smaller areas, a belt of more th:in fifty miles in length of these rocks, called by him I'pper Laurentian, near St. George's Bay. § 30G. The Ifjalities of labradorite rocks on the coast be- tween the Sa'j,uenay and the Bay of Seven Islands, were examined by Mr. James Richardson in 1800, and the ma- terials having been submitted to the examination of the writer, the results are set fortli in Mr. Richardson's report for that year (Report of Progress for lSGG-1800, page :3()5). The Laurentian there consists of coarser and finer reddish and grayish gneisses, often enclosing liornblendic and mi- caceous layers, and including great masses of vitreous (piartz, sometimes pure, and at othor times holdingsparingly disseminated plates of llesh-i'cd feldspar. IVds of cryastl- line limestone, enclosing green pyroxene, are included in the gneiss. § 307. The labradorite rocks there met with present many varieties resembling those found near Montreal. Besides hypersthene, they sometimes include nodular masses of red garnet, and others of a gray fibrous hornblende. Bands niSTORY OF LABRADOPITE ROCKS. E. 159 of anortholites, coarser and finer in texture, and marked by these different minerals, serve to make very apparent the stratification, which is extremely regular, and near Pente- cost River is seen in a range of low cliffs, dipping N". 23° E, < 30° to 40°. At the Bay of Seven Islands, in like man- ner, the dark bluish anortholites, characterized by hyper- sthene, and includinggreat masses of titanic iron-ore, appear for a distance of three or four miles, with a nearly uniform dip of from 10° to 20° to the northward. The reddish Lau- rentian gneiss is in one place "seen to be distinctly over- laid by a patch, only a feAv yards square, of labradorite rock, showing considerable varieties in character, and clearly stratified." § 308. The conclusion from till the ol)servations along this coast is thus stated : For the Laurentian gneiss, "the strike is generally nearly north and south, Avith di^^s often aj)- proaching the vertical. The strata are all more or less brok(Mi, contorted and faulted. The labradorite rocks rest unconformably upon the Laurentian ; they generally strike nearly east and west, at comparatively moderate angles, with little or no appearance of contortion or disturbance." Both the Laurentian and the labradorite rocks are cut by granitic veins containing red orthoclase, greenish oligoclase, black hornblende, muscovite, molybdenite, and sometimes crystalline masses of magnetite. § 309. At an early date in the history of the investiga- tion of the Laurentian its mineralogical resemblances with the Primitive gneiss of Eui'ope wer(^ evident. Th(i writer, in 18i)4, declared that bolli "in i)ositiou and in lithological characters the Laurentian st'iiesaifpcars to corres])oad to the old gneiss formation of L.ii)land, Finland ;ind Scandinavia," (Anier. Journal Science IL xviii, 19;"),) and in the I'J.squ/s.se Gcolof/iquc, already cited, it was added "to the similar rocks of the north [westj of Scotland." In the di^scriptiou then given, the anortholites were as yet regarded as form- ing a part of the Laurentian, and these rocks, as found in Essex county. New York, had. we have seen, been by Em- mons compared with the hy.i)ersthen<^-rock or labradorlte- rock found by Macculloch in the Western Islands of Suot- 1#l 160 E. SPECIAL REPORT. T. STERUY HUNT, 1875. land. In order to verify this comparison, the ■writer, hav- ing- iirst procured specimens of tlie rock from Loch Scarvig in the Isle of Slvye, obtained access to the collections made in that island by Macculloch, and now in the possession of the GeoloL!;ical Society of Lon(hjii, and convinced himself of their close resemblances to the anortholites of New York and Canada. § 310. Both Macculloch and Emmons regarded these lab- i"adorit(; rocks are eruptive, Gi(di.ie, in his subsequent ge- ological studies in Skye, expressed the same view, and ap- peared to confound Ihem with certain eruptive greenstones. The writer s oljservations and conclusions respecting these, and theother crystalline rocks of the Western Islands, were set forth in the Dublin Quarterly Journal for July, 18G3, where the stratified character of the labradorite-rocks of Canada, and their correspond(Mice with those of Skye was pointed out. In the following year Prof. Ilaughton, of Dub- lin, visited Loch Scarvig, in Skye, and in the same Journal for 180.") (i)age G5) describes the rock, which he submitted to analysis, as an aggregate of labradorite, often coarse ^rained, Avith pyroxene and titanic iron, and declared it to be evidently "a bedded metamorphic rock."" §311. Similar anorthosite-rocks Avere known to exist in the gneissic region of Norway, and had been by Esmark called norites, from the name of the country. A careful examination by the writer of a large collection of these, se- lected for ornamental jiurposes, and sent by the Royal Uni- versity of Christiania to the Paris Exhibition of 1807, shoAved them to be precisely similar to the labradorite-rocks of North America. In a printed notice accompanying this collection it was stated that these A'arious rocks, consisting of labradorite with hypersthene, diallage and bronzite. had, in th(^ geological map of Southein Norway, published in 18(5(5, b(>eu designated by the common name of gabbro. This notice at the same time suggested that "the name of norite should be preserved for certain varieties of gabbro rich in labradorite, which varieties may, in great part, Avith justice be called labradorite-rock, since labrador-feldspar is their predominant element." .'fill se- Uni- iwed of this ting lad, I in bro. e of hbro vitli lar is TUE LAKRADORITE OR NORIAN SERIES. E. IGl § 312. The geological map of Nonvay above refen'ed to shows that tliese so-called gabbros occupy (lonsiderable areas within the Laurentian gneiss region of Norway, and are by the authors of the map. KjeiMilf and Dalil, regarded as erup- tive, though they are des('ril)ed by them as often ]>res«Mit- ing the characters of stratified rocks. In fart, the banded stratiform structure of tlu'se Norwegian norites is as clearly marked as that of any of those of North America, horn wliicli they cannot be distinguished. Of the above collec- lion, the norites of Sogndal and Egei-sund presented line varieties of grayish or brownish violent tints, wliile a dark violet norite comes from Krageroc. and also from Laiigoo and Gomoii, and a white gi'anular variety from the (fiilf of Laerdal, in the diocess of Bergen. Very IxMiiriful varie- tius of coarsely granitoid violet coloi-ed norite, often oi)ales- cent, are brought from Southern Russia, wdiere the rot^k is said to form a mountain mass in the government of Kiew. For further details on the norites, both of Norway and North America, see the writer's essay On Norite Rock, read be- fore the American Association for the Advancement of Sci- ence in ISGO, and pnblished in the American Journal of Science for Novemlx^r of that year. § 813. The x>i'ior name of norite was, in accordance with the suggestion of the Norwegian geologists, lienceforth adopted for these rocks in America, and since it was appar- ent that they form a stratiiied series entirely distinct from the Laurentian, the Avriter, in his address before the Asso- ciation just named, in tSTl, substituted, in place of Upper Laurentian and Labradorian, the designation of the Norian series foi* these labradorite or anortlif)site rocks, (See further his Chemical and Geological Essays, pages 270-281). Nothing more is known of the norites there mentioned as found in the vicinity of St. John, New Brunswick, where they occupy a small area in a greatly disturbed district; while the labradoritic rocks in the White Mountains, which had by Hitchcock been referred to norite, are now found by him to be eruptive masses. A few scattered erratic blocks of norite have been found on the New England coast, near the mouth of the St. Croix, and at Marblehead, Massachu- [K. 11] mi m 162 E. SIM'X'IAL IlKPOUT. T. STFCKUY HUNT, 1875. 11 setts, wliil(3 the occurrence of similar masses in greater abundance in northern New Jersey, suggests tlu? possible presence of the Norian aeries among the crystalline rocks of the Highlands. § 314. The presence of titanic iron, approaching menac- canite or ilnienite in conii)osition, seems to be very charac- teristic of the Norian rocks. In Canada, at St. Urljain, at Lake St. John and in the Bay of Seven Islands, are found masses of thi.s mineral so large as to attract attention as to a possible ore of iron (Geology of Canada, pages 501, 754, and report for 1866-09, pages 252, 200). Similar ores are found with the norites of Krageroe and Egersund in Nor- way, and the writer has found an iron-ore from Skye to be of the same sj^tecies. § 315. A blue granitoid norite, and a titanic ore like those of Canada and Norway, are found associated in Wyoming, on the Laramie plains, near the Chugwater creek, and were identified and described from specimens, by the writer, in the Transactions of the American Institute of Mining Engi- neers, in 1873 (Vol. I, 335). Mr. Arnold Hague, in the Sur- vey of tlie Fortieth Parallel (volume II, pages 13-10) has since described under the name of gabbro, .his same norite, which, from its analysis, is shown to be a nearly pure labra- dorite, while the iron-ore holds about one fourth its weight of titanic oxyd. These, though by him regarded as erui)- tive, suggest the existence, in this region, of an area of stratified Norian rocks. § 310. Titanium is not unl■mo^vn in the Laurentian and Huronian iron-ores, though seldom in such amounts as to be prejudicial to their use in metallurgy, but in all the cases with Avhicli the writer is acquainted, the iron-ores of the Norian are so higldy charged with it as to be unfit for use in the blast-furnace. Having been called in 1870 to examine the large deposits of highly titaniferous ores near Westport in Essex county, New York, these were found to be included in tlie Norian rocks of that region, which offer a marked contiast to the Laurentian gneisses near by, in which are included the magnetic ores so extensively mined in the vicinity of Port Henry (Tnins. Amer. Inst, of Mining Engineers, Vol. I, page 335). LEEDS ON THE NORIAN SEKIES. E. 103 'lit § 317. Prof. Jjimes Hull has since examined this ie;:fi()n, and in a communication to the American Association for the Advancement of Science, in 1870, has conlirmcd the writer's observations. Hall distinguishes two parts in tiie crystalline rocks of Essex county, the lower consisting of coarse I'eldspathic and quartzosc rocks (gneisses) often with black hornblende and with garnet, including great beds of magnetic iron-ore. These rocks are ''succeeded by massive beds of labradorite-rocks. This x^a^i't of tlie formation is marked by extensive beds of titaniferous iron-ore. The succession is however unconformable, and the interval be- tween the two series of rocks is not determined ' ' (American Journal of Science, III, xii, 299). § 318. The JS'orian region in Essex county, New York, rises into considerable hills, the highest, Mouni Marcy, being 5,400 feet above the sea, and extends along the hore of Lake Champlain, from near Westport to Port Kent. The rail- way between these two points, in its course around Wills- borough Bay, is cut for about five miles through the Norian rocks, which may, there be studied to great advantage. Prof. Albert R. Leeds, of Iloboken, New Jersey, has lately de- voted much attention to these rocks in Essex county, and has embodied his observations in a paper read before the New York Academy of Science, December 11, 1870, and published under the title of "Notes on the Lithology of the xVdirondacks," in the American Chemist for March 1877, which forms a very important contribution to the hiatory of the Norian series. In this, besides giving an analysis of the previous observations of Emmons, and of the present writer, he has made careful chemical, mineralogical and mi- croscopical studies of the Norian roclvs collected by himself in Essex county. § 319. Rejecting the names of gabbro, hyperite, diorite and diabase, by which many would designate these rocks, he has called them all norites. Some of these are described as porx)hyritic from the presence of polysynthetic ma.-les of smoky bl ii(3 labradorite in a granular or crypto-crystalline matrix, which is often yellowish in color. In some cases this matrix or paste is almost entirely wanting, while in > IMAGE EVALUATION TEST TARGET (MT-3) J: // // ..>" c< x 6' 'C-?- :/. y- 1.0 50 - IIIIIM 3.6 |?.2 I.I i:^ »4_p 12.0 1.8 l> 1.25 1.4 1.6 P^. V] ^c> ^^/ "' ■■«!>• ^Z"' *^ .y^' o /a / /A Photographic Sciences Corporation iV d ■<^^ ^ \ \ 4^ ^. v^Q ;\ ^Z'^% % ^^ <> 2j west main street WEBSTER N.Y 14580 (716) 872-4503 &? w. I':' a !: i I ' ■ I lAli 164 E. SPECIAL REPORT. T. STERRY HUNT, 1875. Others, from the absence of the crystals, we have a compact greenish feldspar-rock, with some admixed diallage and red garnet. This latter mineral is a common element in these rocks, and is generally associated with the non-feld- spathic portion, garnet often bordering the masses of dial- lage. in some instances, by the disapi)earance of feldspar, and the j)redominance of garnet, with some hornblende, the rock passes into a grenatite. Other varieties are described as hypersthenic, liornblendic, and pyroxenic norites. There are also pyroxenites with bnt little admixture of feldspar, and the pyroxene is sometimes broadly foliated and dial- lagic, and at other times green and granular like coccolite. Quartz is generally present, but for the most part in minute particles only visil)le under the microscope. Titanic iron is always found in these rocks, sometimes with magnetite. § 319. Of two analyses by Prof. Leeds, one of the bluish feldsi)ur from the hyx)ersthenic granitoid norite which forms the summit of Mount Marcy, and the other from the yellowish crypto-crystalline paste of a porphyritic norite, both liave very nearly the composition of a proper labradorite. He also analyzed the hypersthene and the diallage of these rocks. (A yeliowish-green gi'anular ep- idote has been found by the writer accompanying a white feldspar in one of the nearly compact norites from this region. ) Prof. Leeds has also given the anal ysis of a reddish granular quartzo-feldspathic rock found among the norites, \vhich contained admixtures of menacannite and magnetite, and yielded seventy -six per cent, of silica, over live per cent, of potash, and three of soda, with but traces of lime. From its chemical composition, and its microscopic charac- ters, it would seem to represent one of the orthoclase rocks which have been described as occurring in the Norian series. Prof. Leeds notes tliat these norites are evidently stratified, and are clearly to be distinguished from the eruptive doler- itic rocks, also described by him, which traverse them. These dolerites have however the same constituent minerals, and, he suggests, may perhaps have been derived fi'om deeply-seated portions of pyroxenic norites. § 320. The calcareous portions of the Lauren tian series i. LIMESTONE VEINS OF THE LAURENTIAN. E. 165 eries are in part pure limestones, and in part either dolomites, or limestones more or less maguesian. They are themselves crystalline, and abound in crystalline species well known to mineralogists. The geognostical relations of these calca- reous rocks offer many x^oints of interest. We have seen that Maclure early recognized the fact that the crystalline limestones of his Primitive Gneiss formation were inter- stratified with the gneissic and granite-like rocks (§ 40). This view was also shared by Nuttall, but Emmons classed the crystalline limestones of northern Now York among the unstratified rocks. Mather, while admitting the strati- fied character of some of them, conceived that certain lime- stones of the region just named were eruptive, and had been "injected in a fluid state." (§ 82-87.) § 321. The studies, by the writer, of the Laurentian limestones of Canada and New York, enabled him, in 1800, to explain these seeming contradictions by showing that besides the stratified limestones, which are clearly indi- genous, and form contemporary portions of the La"rentiau series, there are endogenous masses or concretionary veins of crystalline carbonate of lime, which traverse the gneissic rocks of the series and, containing the same mineral species as the bedded limestones, had hitherto been confounded with these. § U22. The history alike of the limestone beds and the calcareous vein-stones of the Amcn-ican Laurentian, including their mineralogy and lithology, as well as the history of similar crystalline limestones in various parts of Europe, is discussed in the rejoort of the Geological Survey of Canada for 1803-00, pnges 181-229. Tlierein, on page 210, the deposits of franklinite and zincite, with willemite, found in Franklin and Sterling, New Jersey, were noticed, on the authority of II. 1). Rogers, as occurring in veins, while at the same time a doubt was expressed "whether these ores do not, like the magnet- ites, occur in the stratified rocks of the region." The writer's subsequent studies in the localities menticmed have satisfied him that the ores in question are really indigenous interstratified masses. 166 E. SPECIAL REPORT. T. 8TERRY HUNT, 1875. The above essay was reprinted, with some additions, in the Report of the Regents of the University of New York for 1867, Appendix E, and a summary of its principal points will be found in Chemical and Geological Essays, pages 208-219. § 322. Masses of crystalline limestone containing such characteristic minerals as hornblende, pyroxene, serpentine, chondrodite, mica, apatite and graphite may belong either to beds or to veins, and in small outcrops it is sometimes difficult, if not impossible, to distinguish one from the other. The veins are often of large size, and not unfre- quently contain larger or smaller masses of the wall-rock. Such an occurrence appears to have been noticed by Mather, who described a cliff of crystalline limestone, as having " a mass of stratified hornblendic gneiss distinctly imbedded in it." (§ 35). Similar cases are found in North Burgess, in the province of Ontario. § 323. A good example of this phenomenon is seen near the town of Port Henry, in Essex County, New York, in a quarry whence limestone has been got for the blast-fur- naces. Here, irregular elongated angular fragments of dark hornblendic gneiss, from two inches to a foot in thick- ness, Avere found completely enveloped in crystalline car- bonate of lime. In 1877, five such masses of gneiss were exposed in an area of a few square yards. One of these. a thin plate of the gneiss, having been broken in two, the enclosing calcareous matter filled the little crevice, keep- ing the fragments very nearly in their place. The carbon- ate of lime, which is coarsely granular, and contains some graphite and pyrite, is banded with lighter and darker shades of color, and one of its layers was marked by the presence of crystals of green pyroxene and of broAvn spliene. The contact of this mass with the surrounding gneiss, whicli is near by, is concealed. No serpentine was found in this limestone, though it abounds in a limestone quarried in the vicinity. About half a mile to the north is still an- other quarry, opened in a great breadth of more finely granular and somewhat gi-aphitic limestone, which, near its border, presents tliree beds of two or three feet each, inter- LIMESTONE VEINS OF THE LAUKENTIAN. E. 167 stratified with the enclosing gneiss. The first-described locality seems clearly to be a brecciated calcareous vein enclosing fragments of the gneiss wall-rock. § 324. Prof. James Hall appears to have observed simi- lar cases. In the paper quoted above (§ 317) he gives some account of the crystalline limestone, as seen in the vicinity of Port Henry, and says: "Sometimes it is conspicuously brecciated, and contains fragments of gneiss-rock, which seem to have been derived from the strata below, upon which the rock lies unconformably." He concludes that these crystalline limestones do not belong either to the Lau- rentian, or to the unconformably overlying labradorite (No- rian) recks, but to a newer formation. The inclusion of fragments of gneiss is however the only ground assigned in support of the view that these calcareous masses belong to an unconformably overlying formation, and the facts ob- served by the writer lead to the conclusion that the cal- careous masses of the region, except so far as they form in- terstratified portions of the Laurentian or of the Norian series, are to be regarded as endogenous masses or vein- stones — the eruptive limestones of Emmons and of Mather. The banded or stratiform arrangement shown in the distri- bution of the foreign minerals in some of these, is to be compared with the similar structure often observed in gran- itic and other concretionary veins. See for a discussion of this. Chemical and Geological Essays, pages 193, 198 ; and as regards the banded structure resulting from the How of eruptive rocks, page 18G. § 325. Tlie indigenous crystalline limestones of the No- rian, so far as known, resemble those of the Laurentian. The hyi^ersthene rocks of New York, are, according to Em- mons, intermixed and penetrated with a crystalline lime- stone containing the usual characteristic minerals, (§ 88) from which we may perhaps infer that the limestone-veins are common to the Norian and Laurentian series. The age of these veinstones is greater than that of the Lower Cam- brian series, since the Potsdam sandstone in South Burgess, Ontario, has been seen to rest upon the eroded outcrop of p1 I it m ( ; i 168 E. SPECIAL KEPORT. T. STERTIY HUNT, 1875. rolled fragments of one of these veins, and to include apatite, apparently derived from it, § 32(). The finding of the organic form known as Eozoon Canadense marks an epoch in the history of the Laurentian series, and the history of its discovery has been well told by Dr. J. W. Dawson, in his excellent little volume on the subject, entitled The Dawn of Life (London, 1875). There are however two slight corrections to be made tlierein, the first of which regards the argument urged by the present writer in proof of the existence of organic life in the Laur- entian age. This, on page 27 of the volume just cited, (and previously in the Quarterly Journal of the Geological Society, Vol. xxvi. page 113) is said to have been x)ut forth in 18G1, or three years after the discovery of the remains of Eozoon, when they were already supposed to be organic. In fact, the language there quoted from an article in the American Journal of Science of that date, was but a repe- tition of views put forward in the same journal for May, 1858, II, XXV. 420) where it was declared that a great mass of evidence "points to the existence of organic life even during the Laurentian or so-called Azoic period." See also Chemical and Geological Essays, pages 13 and 302. § 327. It was in the autumn of 1858 that Mr. John Mc- Mullen, then attached to the survey of Canada, and an in- telligent and enthusiastic student of geology, who Avas fa- miliar with the above views on this question, and fully ai:)preciated the importance of such a discovery, found in the crystalline limestone at the Grand Calumet Falls, on the Ottawa, specimens of what he believed to be a fossil coral These, he lirst of all submitted to the writer, who then com- pared them with Stromatopora, and laid them before the director of the survey. The appearance of these specimens at once recalled certain specimens similar in form, which had been collected in North Burgess by Dr. Wilson of Perth, Ontario, and by him i)resented to the museum of the geological survey, l>ut had not hitherto been critically examined, ncn* suspected to be organic. The careful mi- croscopic study of the specimens from these two localities, which were submitted to Dr. Dawson, failed to give any -t^— T HISTORY OF EOZOON. E. IGO satisfactory evidence of the true nature of these singular forms, which were however described as probably of or- ganic origin, and ligured in 1802, on page 49 of tlie Geology of Canada, (§ 2U7.) § '328. In 1803, some blocks of serpentinic limestone, pro- cured by the geological survey, and destined for the marble- cutter, were observed by Logan to contain in abundance, forms apparently identic il with those above noticed, but more x^erfectly preserved. These blocks had been got by Mr. James Lowe from a quarry in Cote tSt. Pierre, in the seignory of La Petite Nation, which lies on the north side of the Ottawa River, immediately to the west of Gren- ville. This limestone-quarry, according to Logan, is on the upper limestone band of the Grenville division of the Laurentian (§ 299). The precise horizon in the series of the specimens from the other localities named is not known. Specimens from this new locality were at once placed in the hand of Dr. Dawson, who early in 1804 declared that they were the remains of a foraminiferal organism, to which he gave the name of Eozoon Canadcnse. The iirst an- nouncement of this was made bv the writer in the American Journal of Science for May, 18G4, and in February, 1805 there appeared in the Quarterly Journal of the Geological Society of London, a description of Eozoon by Dr. Dawson, together with discussions of its geological and mineralogical relations by Logan and the present writer. For further de- tails, and for the subsequent history of Eozoon, the reader is referred to Dr. Dawson's volume already quoted, and also to Chemical and Geological Essays, pages o03,-4ll. § 329. Within the liniits of the region in Canada origi- nally described as Laurentian, there are, besides the Lauren- tian and Norian series, other and more recent crystalline stratified rocks, which require description. An area of these has for many years been known in the county of Hastings, which extends northward from the eastern por- tion of Lake Ontario. The rocks in question were Iirst noticed by ;Mr. Murray in his report for 1852 (pages l()4-l()r)) as '•interesting diversities in the Laurentian series," seen in the towns of Madocand Belmont. They were described ii ^1 f'' i\ fl 170 E. SPECIAL REPORT. T. STERRY IHrNT, 1875. by him as consisting of fine grained silicious clay-slate, passing into micaceous and talcose slates, often calcareous and pyritiferous, and sometimes holding crystals of mag- netite, associated with which were great beds of conglom- erate, including pebbles of quartzite, with others of green- stone and of a reddish feldspathic rock. In addit'^n to these, were beds of granular magnesian limestone, some- times becoming schistose. These strata were said to have a moderate dip to the southeast, but their relation to the gneissic rocks of the surrounding region was not determined. § 330, The schistose rocks in the townships named, and in some others adjacent, were again examined in 1864, by Mr. Thomas Macfarlane, and noticed by him in the report for 1863-GG (pages 93-94). The argillaceous and micaceous slates, associated with conglomerates, were further described, and were said to graduate into the limestones of the series, of which two varieties were noted, the one distinctly crys- talline, white or gray in color, often banded, sometimes micaceous, and quarried as a marble, the other finer grained, less crystalline, and of a dark gray color. Macfarlane also noticed in Elzivir and Madoc considerable areas of another group of strata, distinct alike from the last and from the gneisses of the region, and consisting chiefly of pyroxenic and homblendic rocks, the latter some- times becoming micaceous. These were described as form- ing varieties of diabase and of diorite, and passing into diorite-slate and chlorite-slate. He also noticed the occur- rence of a red petrosilex porj)hyry. The rocks of this group were found by him to include the magnetic iron- ores of Marmora and Seymour. § 331. Macfarlane was disposed, on lithological grounds, to regard these two groups of schistose rocks as belonging to a newer series than the surrounding Laurentian gneisses, and compared some of them to the Huronian, but Logan, in a foot-note to the report, on page 93, objected this view, and suggested that "the Hastings rocks may be a higher portion of the Lower Laurentian series than we have met elsewhere." He further remarked that wiiile these rocks offer certain resemblances with the Huronian, and with the THE HASTINGS SERIES. E. 171 crystalline rocks of the Green Mountain range in Cnnada, "the micaceous limestones of Hastings more closely resem- ble the micaceous limestones which run from Eastern Can- ada into Vermont, on the east side of the Green Mountains." These, however, it was argued by him, from the evidence of associated fossiliferous strata, are Devonian, while "the Hastings limestones, which are highly corrugated, are uncon- formably overlaid by horizontal beds of the Birdseye and Black-River limestones." He added in proof of their re- lations to the Laurentian, that these Hastings limestones hold Eozoon Cariadense. § 332. Fragments of Eozoon had already been detected by Dawson in 1866, in a specimen of the limestone from Madoc, collected many years previously by Logan. In that same year Mr. Henry G. Vennor was sent to begin a detailed examination of the rocks of the " Hastings series," as it was then called, and, his attention having been called to this matter, he found in the township of Tudor, numerous specimens of the Eozoon "imbedded in an impure earthy dark gray limestone, with which, and with carbonaceous mat- ter, the cavities of the white calcareous skeleton are filled ; " unlike the greater number of the specimens from the Ottawa, which are filled by serpentine or by pyroxene. These speci- mens were examined, figured and described by Dawson, and an account of their geological relations, so far as then known, was given by Logan in the Journal of the Geologi- cal Society for August, 1867. He there expressed the opinion that " the Hastings series may be somewhat higher than that of Grenville." § 333. In the report for 1866-69 (page 144,) and in that for 1870, (page 310) Mr. Vennor gave the results of his obser- vations in Hastings and some adjoining counties, during the four years, 1866-69, his materials having previously been submitted to the examination of the waiter. The various crystalline rocks, with a northeast and southwest strike, come out from beneath the fossiliferous limestones of the Trenton group, which have here a gentle southward dip, and occupy the southern townships of Hastings county, besides forming some small outliers further north, in Elzivir, Mar- .rl % If 172 E. SPECIAL REPORT. T, STERRY HUNT, 1875. mora and Madoc. These crystalline rocks were included in three groups, as follows, in ascending order: I. A miuss of reddish granitoid rock with olisnuro marks of striitifictitioii, followed by several thousand feet of gneisses with crystallino limestones and beds of magnetite. Tlicse rocks liad all the cliaracters of the Laurentiaii, to which they wore referred. II. A series of dioritic and diabasic rocks, massive and snhLs- tose, sometimes conglomerate, passing into chloriticfichists, with beds of steatite, magnesian limestone, and petrosilex, and with magnetite and hematite ores. These rocks, luiving an estimated thickness of nearly 10,000 feet, were regarded as Iluronian. III. The series of bluish and grayish, occasionally glossj' slates, quartzites, conglomerates, and limestones, already described in § .'5.10, .l.'JI. Tlie conglomerates include peb- bles of quartzite, of greenstone, and of gneiss. The crys- talline dolomites are near the b.xso of the series, while the fine grained, grayish, more or less sciiistose and eartliy limestones, containing E(>zoon, form the upper 1,000 leet of the series, which has a probable thickness of about 3,800 feet. § 334. The provisional name of the Hastings series will be reserved for division TIL The strata of both I and II are described as generally vertical or highly inclined. The strata of division HI are arranged in several synclinals, with moderate dips, and rest unconformably both on the Laurentian and upon the Iluronian series. The frequent aV)sence of the latter at the base of the Hastings series, in- dicates the existence of two stratigraphical breaks in the succession of these crystalline strata. The rocks of divis- ions II and III are traced northeastwards, out of the county of Hastings, across that of Lenox and Addington, and of Frontenac, into Lanark and Renfrew, and nearly to the Ottawa river, a distance of about eighty miles along the strike. § 335, There appears however, to be still another group of crji'stalline rocks in the region under examination. The rocks of the Hastings series, in the township of Levant, are bounded to the west by an elevated ridge of the underlying red Laurentian gneiss, by which they are separated from THE MICA-SCHIST SERIES. E. 173 a series of mica-sohisfs and gneisses. These extend north- ward through Levant, Pnlmerston, and Blytlitield, where they are found dipping at low angles to the east nnd west, occasionally attaining 4.')°, and soniftiines Uf^arly liorizon- tal. They consist of friable (piai'tzose mica-schists, some- times line grained and ferruginous, but often made up in great part of large distinct laminae (-)f silvery-white mica. With these are associated grayisli white tine-grained gneisses, bla(;k hornblendic beds, and small bands of gran- ular limestone. These rocks were, in the report for 1870, (l)age 311) compared with the mica-schists and gneisses of the AVhite Mountain series, and with similar rcx'ks from about Lake Superior. At the same time, they were said to resemble some parts of the Hastings series, as seen in Ma- doc and Tudor. § 330. In the report for 1874 (page 124) Mr. Vennor has farther described this so-called Mica-Schist series, whicli is said to have a breadth of about one and a half miles in the first two townships mentioned above, and to have to the west of it a considerable area of the gi'ay line-gi-ained and friable gneisses. From tlie relations of tliese to certain similar strata found farther to the southeast, Vennor con- cludes tliat these gneisses and mica-scliists occupy a posi- tion above division II, and beneath tlie limestones of III. Their precise relations to these latt(M' does not however ap- pear. The mountain-belt of red granitoid gneiss, already described as separating these limestones and calcareous schists on the east from the Mica-Schist series on the west, has a uniform eastward dip, and seems to overlie the lat- ter, an appearance supposed by Vennor to be due to an uplift of the older formation. In the report last quoted there are also described, under separate heads, groups of granitoid and hornblendic rocks, which are probably to be regarded as portions of one or the other of the lower divisions. § 337. In the years from 1869 to 1874 Vennor was en- gaged in examining the distribution of the crystalline rocks to the southeastward of the belt above mentioned, across the counties of Lanark and Frontenac, as far as the western -■j- J 'i i 174 E. SPKCIAL REPORT. T. STERRY HUNT, 1875. border of the Ottawa paleozoic basin. In the report for the last mentioned year he has described the apparent succes- sion of the Laurentian rocks, as deduced from many ob- servations in the townships lying to the westward of the town of Perth. A section is given for a distance of )out six and a half miles across the strike of the rocks, which have a constant dip to the southeast, varying from forty to eighty degrees. The transverse surface-measurements and the observed dips of each sub-division are given, but no at- tempt is made to estimate the vertical thickness of the several masses. § 338. Beginning at the west, we have, in ascending order, as f oUows : 1. Red gneiss, with hornblcndlo strata (40O-fi0O) . 3500 foot. 2. White higlily crystiillino limestone, witli serpen- tine and graphite, and some interstratiiied horn- blcndio gneias (40O-<)0O) 2G00 " 3. Ilornblendio gneiss, passing into gneissoid and granitoid liornblondic diorites, with grains and layers of epidote, and small included bands of crystalline limestone (GQO-SGO) 5500 " 4. Gneissoid rock consisting of white feldspar, horn- blende and quartz (4r)O-80O) 1500 " 5. White limestone, coarsely crj'stalline, with yel- low mica and graphite, and included bands of orthoclase and quart&rock (00°) 2600 '• 6. Red and dark-colored gneiss and hornblende- rock, with great beds of magnetite and small bands of crystalline limestone (4oO-C0O) . . 7900 " 7. White limestone, very coarsely crystalline, with disseminated chor..rodite, mica and graphite, and including layers of quartzite and horn- blendic gneiss (450-80°) 2G00 " 8. Red granitic and hornblendic gneiss (450-80°) 2G0O " 9. Crystalline limestone like 7, ((iOO-SOO) ; from GO to 100 " 10. Red gneiss and hornblende rock, with beds of magnetite (80°) 1300 " 1 1. Red gneiss with marked stratification, becoming fissile near the summit, Avhere it holds beds of flesh-colored crystalline limestone with black spinel (400-80°); 3000 to jOOO " § 339. In view of the persistent eastward dijD of these rocks, and the great difficulty of distinguishing between different masses of similar gneisses and crystalline lime- VETN'NOR ON TnE LAURENTIAN. E. 175 stones, it must remain a question whether the numbered sub-divisions of the above section are to be regarded as members of a consecutive series, or, in part, as repetitions, through sliarp overturned folds, or through faults, as ap- pears in the example mentioned in § 330. and is so gener- ally the case in the strata of the Atlantic belt. In the rase of the Ottawa section, (§298) Logan was enabled to establish a succession by showing the recurrence of the masses on the opposite sides of a synclinal, but in the present instance, the immediate superposition of the paleozoic strata, to the eastward, makes this method impossible. § 340. To the above series, with a breadth of 35,500 feet, succeeds, according to Vennor, another calcareous belt, not described, and above this what he regards as the highest member of the system, noticed in detail in the report for 1872-73 (page 1C2) as lying in shallow and frequently over- turned synclinals. The rocks of this highest member are displayed along the Rideau canal, in North Burgess, North Crosby, Bedford, Loughborough and Storrington. Their vertical thickness, in dilferent sections, was estimated at from 2600 to 3900 feet. They are described as reddish gneisses, in parts abounding in red garnet, and including two bands of crystalline limestone, with beds, both near the base and the summit of the series, characterized by a predominance of greenish pyroxene, and designated as granitoid pyrox- enic gneisses, passing into a pyroxenic schist with gar- nets. Apatite is found, both disseminated and fomiing layers, alike in the limestone and the pyroxenic rocks, and also in short irregular veins cutting the strata. The mineralogy and lithology of tliese rocks, was previ- ously described at some length by the writer in the report of 18GG-G9 (pages 224-229) and the characters of the pyrox- enic masses were noticed in the Geology of Canada (1803) page 475, where the associated feldsi)ar is shown to be orthoclase, often with sphene and with qujirtz. § 341. The limestones of this upper member which, ac- cording to Vennoi', are distinguished from those below them by the presence of apatite, contain the Eozoon found in North Burgess, and are conjectured, from their mineral '^ 176 E, SPECIAL IIEPOIIT. T. STEKRY HUNT, 1875. Ijil! II 11 ■ !i' ir '.'if. associations, to bb the same v/ith the upper limestone band of the Grenville series, which yiekls the Eozoon of Cute St. Pierre, In chis series, according to Logan, there are but tliree great limestone bands which, with their associated gneisses, were described as constituting an ''upper group" or system, overlying the ''lower groiij)" of granitic or sye- nitic gneisses without limestone, which we have called the Ottawa gneiss. Mr. Vennor, in a late note in the American Journal of Science, for October, 1877, api^ears to have over- looked this distiiu'tion, pointed out by Logan in 18-17, and claims the merit of having distinguished between the "old fundamental red gneiss system" without limestones, and the great oveilying series of gneisses with crystalline lime- stones, which he calls his "second system," and with the limestone bands of which, he asserts, are found all the eco- nomic minerals of the Laurentian. This was already pointed out by the wri';er in the report for ISOIi-GG (page 18G) where, after d*^signating these limestone bands of the Grenville se- ries, with their "attendant pyroxenites, amphibolites, ser- pentines, magnetites, etc,' as so many *'limest(megroui:)s," it was said " the ores of iron, copper, nickel, and cobalt, t]\e apatite, mica and plumbago, as well as the serpentines and the marbles of the great Lower Laurentian series, belong, so far as yet known, to the limestone groups." It will be remembered that the teim Lowei' Laurentian, then used, included both the lower or Ottawa gneiss and the rocks of th(> Grenville series. Jj 842. This lower gneiss has by the \vr:ter been compared witli the oldest red gneiss of Bavaria, called Bojian by G um- bel, and the Grenville series with the overlying Hercynian gneiss series of the same author, which, like the similar rocks in Canada, includes great beds of crystalline lime- stone, with serpentine, chondrodito and graphite, and con- tains Eozooii CaiKKlcnse. (American Journal of Science for July 1870, II. 1., 90.) ^ 'M'i\. Mr. Vennoi- believes that there is a want of con- formity between the lower "system," or the Ottaw agneiss, and tlic u])per "system," or Grenville series, and farther suggests that tlie rocks of divisions II and III in Hastings DAWSON ON THE HASTINGS SERIES, E. 177 5) Giirn- bynian limilar lime- H con- •ience If con- [iieiss, lirther stings county (§333) are "simply an altered condition, in their westward extension, of the lower portion" ol' this upper or Grenville seiies ; a gratuitous hypothesis, in support of which he offers no argument, and which it is unnecessary to discuss. The only i~)oint of relation between these most unlike groups of rocks is that Eozoon Canadense is com- mon to the limestones of the Grenville and the Hastings series. § 341. Other indications of organic life than Eozoon Can- adense, have been found in the rocks of the Hastings series. In his original paper on the Eozoon, in ISCo, Dr. Dawson announced that in some of the dark-colored imi)ure lime- stones of this series, from Madoc "there are iibres and gran- ules of carbonaceous matter, which do not conform to the crystalline structure, and present forms quite similar to those which in more modern limestones result from the decomposition of algsD. Though retaining mere traces of organic structure, no doubt would be entertained as to their vegetable origin if they were found in fossiliferous lime- stones.'" lie noticed also a similar Imiestone from the same vicinity, which is apparently "a iinely laminated sed- iment, and shows perforations of various sizes, somewhat scalloped on the edges, and idled with grains of rounded silicious sand." Other specimens from the same region were said to have indications on their weathered surfaces, of similar circular perforations, having the asx)ect of Sco- lithus or of worm-burrows. Some of these markings from Madoc were subsequently figured by Dawson, and desig- nated "aimelid-buiTows," with the remark that "thnrecan be no doubt as to their nature," (Dawn of Life, page 140). The position of these is in the Hastings series. ^ 342. The geologist familiar with tlie crystalline strata of the Atlantic belt, finds all its principal types repeated in the limited region included in Hastings county and its northwestern extension towards the Ottawa. The rocks of division II serve to connect the Huronian of Lakes Superior, Huron pud Temiscaming with the similar rocks of north- esistern America, where also the mica-schists resembling those just noticed are widely spread. Rocks of this latter [E. 12] i i \f 1^ I I - I 178 E. SPECIAL REPORT. T, STEKRY HUNT, 1875. type were noticed in 1824 by Dr. Bigsby, about Lake La- croix and Rainy Lake, to tlie northeast of Lake Superior, and both these and the cliaracteristic rocks of the Huron- ian were then described by that excellent observer, (Ameri- can Journal of Science, I, viii, Gl). These various crys- talline stratii were, by him, conceived to belong to what, in the language of the time were called "transition rocks." From these descrii)tions, and from the examination of collec- tions, the writer, while noticing in 1861, the observations of Bigsby, asserted " the lithological and mineral characters of these crystalline strata seem to be distinct from those of the Laurentian system, and to resemble those of the Appala- chians." (Ibid, II, xxxi, 395). Subsequently, in 1870, the conclusion was reached that "there exists to the northwest of Lake Superior an extended series of crystalline schists unlike the Laurentian, and resembling those of the White Mountains." (Ibid, II, 1 85). David Dale Owen had noticed and described in 1853, similar crystalline rocks, as seen in Iowa and Wisconsin. § 343. Logan, in 1806 pointed a similarity between the rocks of the Hastings series, and certain strata along the eastern base of the Green Mountains in Canada and Ver- mont, (§ 331). It was moreover evident that these lime- stones, slates and quartzites of central Ontario had close resemblance with those strata in western New England, which Emmons had t the men- !S 590 .f the hinion is in Ists to Lid to Jystal- llarecl, *aleo- snx)- [hists. [lypo- fiinial conglomerate and the Primnl older slates, surreedino; which, in ascending order, was the Primal white sandstone, re- garded by him as the equivalent of the Potsdam sandstone, the base of the New York paleozoic series (J 4-7). Thus the crystalline schists between the ancient gneiss and the Potsdam, which, in 1840, had been by Rogers included in the Primary (§ C2) were now, in 1808, called paleozoic, though still assigned to the s;ime geological horizon as be- fore. In fact, while seeming to accept the hypothesis of a metamorphic jiah^ozoic series, Rogers novNr held substan- tially the views of Eaton and of Emmons as to the existence of a gi'eat crystalline series lying above the older gneiss, but below the Potsdam. The similar crystalline rocks of the Green Mountain range, on the contrary, were, accord- ing to Logan, the metamorphosed strata of the Quebec group, and belonged to a horizon above the Potsdam sand- stone. § 859. The crystalline schists which in Caernarvonshire and Anglesea are found at the base of the sedimentary series, were at iirst, in 1835, included by Sedgwick with the latter, as a lower member of his Cambrian system. In 1838, however, he separated these crystalline rocks from the Cambrian, and henceforth regarded them as belonging to an older series, a view which was shared by John Phillips, (Chem. and Geol. Essays, pages 353, 383). Murcjhison, fol- lowing Delabeche, called them altered Cambrian, and havirig suggested to Logan that the Huronian series of Canada might be the equivalent of these crystalline strata of Caer- narvonshire and Anglesea, the name of Cambrian was, for a time, occasionally used by the geological survey as synon- ymous with Huronian, until Bigsby, in 18G3, in a paper already cited (§ 145) showed that the only strata to which the name of Cambrian clearly belonged, were uncrystalline sediments, and that the Huronian rocks were to be referred to a more ancient series, the Primitive schists of Norway. Nicol has maintained, in opposition to Murchison and Giekie, similar views with regard to the rocks of the Scottish High- lands which, according to the writer's observations, are ni I nil } y I! i 'i' ! ■;: I f$h 188 E. SPECIAL RKPORT. T. STERllY HUNT, 1875. itlontical with tlio primitive crystalline schists of North America. (Ibid., pages 271, 272). § 360. Tlie writer, from his studies of these crystalline rocks of Wales expressed, in 1871, the opinion that they are identical with those of the Green Mountain or Iluronian series, (Ibid., pages 2G9, 353, 383). These rocks as dis- played in Caernarv(msliiro, and similar ones near St. David's in South Wnles, hith«n-to regarded by the geological survey of Great Britain as in part altered Cambrian, and in part eruptive, are now shown by Hicks to lie uncomformably be- neatli the Cambrian, and are referred by him to a lower group named Diraetian, and an upper called Pebidian. According to McKenna Hughes however, these two consti- tute but a single conformable pre-Cambrian series, the litho- logical descriptions of which seem to show that, like the rocks of Anglesea, (already classed with them by Sedg- wick, and by the writer,) they also bekmg to the Iluronian series. (Proc. Geol. Soc, London, Nov. 21, 1877.) § 301. In a paper on the Geology of St. John County, New Brunswick, published in the Canadian Naturalist in 18(53, and re-printed in part in the geological report of Canada for 1870-71, page 23, Mr. George F. Matthew de- scribed, under the name of the Coldbrook group, a great mass of crystalline strata found in southern New Bruns- wi(4v, to the east of the river St. John. These rocks repose on the Laurentian, and underlie unconformabh' the uncrys- talline Lower Cambrian slates of the city of St. John, which include, near their base, conglomerates holding fragments of the Coldbrook group. From this, and from their litlio- logical characters, these older rocks were, by Matthew, re- ferred soon after to the Iluronian series. (Quar. Jour. Geol. Soc. Nov., 180.")). They have since been found to rest unconformably upon the Laurentian, i)ebbles of which are contained in the conglomerates of the Coldbrook group. § 3G2. In the paper which contained his account of the Coldbrook group, in 1803, Mr. Matthew described a second belt of crystalline rocks similar to these, to which he gave the name of the Bloomsburj^ group. These, ajiparentlj'- resting upon the Menevian, and conformably overlaid by great runs- epose ncrys- whicli irients itlio- r, re- Jour. rest U are ip. t)f the econd 3 gave ently id by IIUIiONlAN li(J(,KS 1\ \E\V K\(JLAN'D. E. 180 the fossil iferous Devonian sandstones of 8t. J(din, were, at tliat time, called by him altered Devonian strata. In 18(50 and 1870, however, the writer devoted some weeks, in connection with Prol". L. W. I3ailevand Mr. M;itrliew. to tln! investigation of thegeology of southern Xcw Hninswick, when it appeared that the J31oomsbury rocks wern but a lepetition of the Coldbrook group on the opposite si(h; of a closely folded synclinal holding Lower Cambrian sediments. Accordingly, in the gecdogical report of the gentlemen Just named, both of these belts were designated as Ilui-onian ; in which were now also included two other sulidivisions of crystalline rocks found in that region, and previously designated the Coastal and Kingston gi'oups. (Repoi't of Geol. Sur., 1870-71, pages 27, 00, 04). § 303. These lliironian rocks were traced in 1809 and 1870 along the southern coast of New Brunswick, from the liead of the Bay of Fundy to the conlines of Maine, as was stated by the writer in July, 1870, when these rocks, "called Cambrian and Iluronian by Mr. Matthew," and character- ized by the oc(!urrence of diorites and quartziforous feld- spar-porphyries, were said to occur in Eastport, Maine, and in Newbury, Salem, Lynn, and Marblehead, Massachusetts. (Amer. Jour. Science, II, 1, 89). In October of the same year, after a further study of these rocks in the vi(nnity of Boston, and at New^port, they were described as follows by the writer in the Proceedings of the Boston Society of Natural History, (vol. XIV, pages 45, 40). § 304. The crystalline stratified rocks in question, it was said, "may be sei)arated lit hologically into two divisions, the first being the quartzo-feldspathic rocks. Among these are included the felsite-porphyries of Lynn, Saugus and ]\Iar- blehead, with their associated non-porphyritic and jasper- like varieties, the compact feldspar of Hitchcock, who has well described these rocks in the C+eology of Massachusetts, pages 004, 007. Associated with them is a granular quartzo feldspathic rock, which is often itself porphyritic, with feldspar crystals, and sometimes appears as a fine- grained syenitic or gneissoid rock, often distinctly strati- fied. This has been described by Hitchcock as intermedi- ■1^ ■ 190 E. spp:cial report, t. steury hunt, 1875. ate between porphyry unci syenite ; his syenites with a nearly or quite compact feldspar base, and some of his por- phyritic syenites, (Ibid., pp. 008, 000) will probably be found to belong to these granular euritcs, which I connect with the porphyries. These rocks are seen intimately associated wi th the porphyry on Marblehead Neck ; also in Marblehead, and underlying the argillites of Braintree and Weymouth." § 305. The second division of these rocks " includes a se- ries of dioritic and chloritic rocks, generally greenish in color, sometimes schijtose, and frequently amygdaloidal. They often contain epidote, quartz and calcite, and occa- sionally actinolite, amianthus, scaly chlorite and copi)er- pyrites. This series holds " * serjtentine in Lynn- field, where bedded serpentines, dipping at a high angle to the northwest occur, apparently in the strike of these dioritic and epidotic rocks, which include the green- stones of Dr. Hitchcock, described by him as occasionally schistose, and passing into hornblende slate, (Ibid. pp. 548, 647) ; and also his varioloid wacke, under which name he describes the green and chocolate-colored amygdaloidal ep- idotic and (;hloritic rocks of Brighton, and the somewhat similar rocks of Saugus, which are seen within a few hun- dred feet to the northwest of the limit of the red jaspery petrosilex. This series of magnesian rocks is apparently identical with that which occurs with dolomite and massive dark-colored serpentines, in the city of Newport, Rhode Island, wliere the beds have also a high dip to the north- west." §300. "A similar series of strata is largely displayed on the islands, and along tlie shores of Passamaquaddy Bay. Tlie dioritic and chloritic beds towards their base are there inters tratified with red felsite-porphyries '■' * * * which, associated with granular eurites, form great masses in that region. I regard these two types of ro(;ks as form- ing parts of one ancient crystalline series, which is largely developed in the vicinity of Boston, and may be traced at intervals from Newport to the Bay of Pundy, and beyond. To this same series I refer the great range of gneiss ic and dioritic rocks, with serpentines, chloritic, talcose and epi- IIUKONIAN K0CK8 IN NEW ENGLAND. E. 191 these dotic schists, which stretches through western New Eng- land" — that is to say the Green Mountain range. § 307. These rocks were then described as ' ' penetrated by intrusive granites, generally niore or less hornblendic — the syenites of Hitchcock and others. They often contain two feldspars, as in the well-marked granite of Newport, Rhode Island, wliich there cuts the greenish dioritic and sometimes amygdaloidal rocks. ' ' The granites of Cape Ann and Quincy are there said to belong probably to this class, besides which examples are seen "at Stoneham and in Marblehead, where they intersect the greenish chloritic rocks, and on Marblehead Neck, where they are erupted among the felsite-porphyries." The crystalline rocks of this ancient series were shown to be overlaid by the uncrystalline sandstones, conglomerates and argillites, including those which at Braintree hold a Lower Cambrian fauna, and rest upon the folsite-porphyry. § 368. Tlie feldspar-porphyries above described were by the late Dr. Hitchcock in 1844, classed among unstratilied rocks, which had "once been melted." In tliis class also he placed the whole of the so-called syenites and green- stones, which were made by him to include, besides truly eruptive masses, many indigenous rocks. The serpentines and amygdaloids were, however, correctly described as stratified rocks. Another type of rocks, apparently distinct from the Huronian series, and occupying a small area on Marblehead Neck, was described in the above pages as thin-bedded quartzites, holding dark micaceous layers, and becoming gneissoid in aspect. Tiiese, which were supposed to be newer strata than the Huronian, are also cut by intrusive granites, which, in their turn, are intersected by eruptive greenstones, having a genend resemblance to certain in- digenous rocks of the ancient series. § 309. The petrosilex rocks of the above series were further described in February, 1870, in the following lan- guage: "Felsites and felsite-porphyries are well known in eastern Massac^husetts, * * * j^j^j jxvav be traced from Machias and Eastport in Maine, along the n f. -I ty U !!l 192 E. SPECIAL liEPoirr. t. steuhy iii^n't, ISTo. southern coast of New Brunswick, to the head of the Bay of Fundy, with great uniformity of type, though in every phice subject to considerable variations, from a compact jasper-lilve rock to more or less coarsely granular varieties, all of Avhich are often porphyritic from feldspar crystals, and sometimes include grains or crystals of quartz. The colors of these rocks are generally some shade of red, vary- ing from tiesh-red to purjole ; pale yelhnv, gray, greenish and even black varieties are however occasionally met Avith. These rocks are. throughout this region, distinctly strati- fied, Jind are closely associated with dioritic, chloritic and ei:)id()tic strata. They apparently belong, like these, to the great lluronian system." (Amer. Jour. Science, III, i, 84). § 870. The composition of these rocks is shown by the fol- lowing hitherto unpublished analyses of three typical spe- cimens, collected by the writer, which were made by a former assistant, Mr. Gordon Broom(\ I. was a pale red compact variety, with feldsjiar crystals, and had l)een de- scribed as a "porphyritic slaty quartzite," from the Cold- brook group iif'nr St. John, Xew Brunswick; II. was a similar, but darker red variety from the same vicinity ; III. was a pur])lish-ied line grained and homogeneous variety from Newl)ury, Massachusetts. The analyses were made tlie aid of lluorhydric acid, and the silica determined by difference : i 1 l| 1 I. II. in. Silica 81 .00 7.43 2.20 1.43 .71 4.04 1.72 .21 79.82 8.87 3.80 .01 1.83 3.80 1.58 .14 79.03 0.07 2.87 .20 .01 f) 10 1.45 .47 1 Aliiiiiiiiii FcMTio oxyd, Tjiiiio, Mii'^nosia. .... ... I'otiisli, Soda. Volatile) Spocitic emvitv 100.00 100.00 100.00 2.041 2.000 2. 028 Their chemical composition indicates that these rocks are composed chielly of orthoclase and quartz, a conclusion HUUONIAN ROCKS JX PENXSYLVANIA. E. 103 wliich is confirmed by the microscopic study of the com- pact or crypto-crystalline varieties. § 371. It was, as we have seen in 1870, that the Hnronian rocl^s of tlie Atlantic coast were declared to be the equiva- lents of the Green Mountain series. In the writer's address to the American Association for the Advancement of Science in August, 1871, tliis view was developed more at lencth, and an attempt was made to trace, from the facts then known, this Green Mountain or Iluronian series, from East- ern Canada through New England into Pennsylvania, and thence into North and South Carolina. (Chem. and Geol. Essays, pages 243-250). In 187i), while examining the South Mountain to the west of Gettysburg, in Pennsylvania, he discovered a remarka- ble and hitherto unrecognized area of the Iluronian series, characterized by a great development of the petrosilex-por- phyry, which was thus described in August, 1870: "There is here found a great breadth of this rock, distinctly bedded, presenting different varieties, and alternating withdioi-itic or diabasic, epidotic and chloritic rocks, and with ai-gillites, in which are sometimes included thin beds of the j^etrosilex ; the strata generally dipping at high angles to the southeast." These were then compared with the similar strata along the Atlantic coast, from Rliode Island to New Brunswick, "in- terstratified, as in the South Mountain, with rocks having the characters of the Iluronian series, to which gietit divi- sion I have provisionally referred these bedded ix'ti-osilex rocks, with the suggestion that they probably occupy a. positi(m near the base of the series." (Proc. Anier. Assoc. Ad van. Science, 1870, pp. 211, 212.) ^ 372. These rocks were then declared to be identical in lithological characters with the hallellinta. or stratified tlint-i'ock, of the Swedish geologists, which is by them as- signed to a horizrm just above the more ancient or Primitive gneiss, and is important as including in Noi-way the most ('(msidei'able deposits of crystalline iron ores. These same rocks are met with in various localities in the Huronian se- ries, (m the upper lakes, and are well displayed, as oljserved by the writer, in a small island lying a little to the south [E. 13.J I :4 F 104 E. SPECIAL REPORT. T. STERRY HUNT, 1875, of St. Ignace island, and for some distance along the shore of the adjacent mainland, to the southwest. § 373 In the same paper these petrosilex rocks are com- pared with the iron-bearing quartziferous porphyries of southeastern Missouri, a comparison previously made more at length by the writer in a review of the Rej^oit for 1873 on the geological survey of that State. (Am. Naturalist, April, 1875.) The isolated hills which there rise through the horizontal Cambrian strata deposited around their base, are in some cases of quartziferous porphyry, and in others of a granitoid rock, sometimes capped with the porphyry, which is regarded by Prof. Pumpelly as a younger and a stratififMl rock. Wlule, for tho most part, a petrosilex, some- times spherulitic, and often i^orphyritic, it may, as was ob- served by the writer at Shepard Mountain, become gneissoid from a considerable admixture of crystalline quartz, inter- laminated with a red granular orthoclase. In one locality these rocks include layers, sometimes several inches in thick ness, of pink and greenish crystalline carbonate of lime, interstratilied with a jaspery schistose variety of petro- silex, which, in some layers, is intimately mingled with the carbonate of lime. In the Pilot Knob, beds of argillite, sometimes more or less talcose in aspect, are found with the porphyritic petrosilex. § 374. Epidote, chlorite, and a steatitic mineral are occa- sionally met with in these petrosilex rocks, and magnetic and specular oxyds of iron occur disseminated, in interstrati- lied masses, and in veins intersecting the strata, as has been well described by Dr. Schmidt in the report already named. Oxyds of iron, ;n some instances manganesian, are also found forming the buGo of a porphyritic mass, which holds crystals of orthoclase and grains of quartz, suggest- ing to Prof. Pumpelly the hypothesis of a replacement of the petrosilex itself by these metallic oxyds. He how- ever inclines to another hypothesis, suggested by the ad- mixture of carbonate of lime with petrosilex, above de- scribed, and conceives that both ihepetroeilc:;; and the iron- ore may have been derived by a metasomatic process from a limestone, parts of which were replaced by the oxyds of iU' IIURONIAN BOOKS I]^f NPIWFOUNDLAND. E. 195 rgest- Iment liow- [e ad- de- liron- ll'rom [(Is of iron and manganese, "while the porphyry now surround- ing tlie ores, may be due to a previous, contemporaneous, or subsequent repla(;eraent of the lime-carbonate by silica and silicates." The fact is noted that chemical analysis shows that the remaining porphyry, intimately associated with the ore, or with the limestone, has undergone no change, but retains its normal constitution, corresponding essentially to an admixture of orthoclase with quartz. § 375. The northeastward extension of the Green Mount- ain range in Canada, its disappearance, and its re-appear- ance in the Shickshock Mountains, have already been de- scribed (§ IGG, 167). It remains to be mentioned that near the eastern extremity of Gasp<5, the rocks of this series, consisting of chloritic and nacreous schists with serpentine, appear in a hill about thirteen hundred feet in height, which has been named Mount Serpentine. It is situated on a tributary of the river Dartmouth, not far from the head of Gaspd Bay, and rises in the midst of the uncrys- talline sediments of the Quebec group, where its appear- ance is probably due to a dislocation. (Geol. of Canada, pages 270, 406.) ^ 376. In Newfoundland, the crystalline strata of the Green Mountain series are largely developed both in the central and northwest parts of the island. Those in the latter region, were studied many years since, and were de- scribed in the Geology of Canada as belonging to the altered Quebec group. The facts observed with regard to their geological relations at Pistolet Bay and Bonne Bay, have already been given. (§ 218, 219, 226-229.) In 1864, ]\Ii'. Alex. Murray began a systematic geological survey of Newfoundland, and in hU first rej)ort, in 1805, described with detail the furthiM* distribution of these crys- talline rocks, which he continued to regard as the altered equivalents of the middle portions of the Quebec group, occupying a jDosition immediately below the Sillery sand- stone. (§ 352). § 377. The subsequent researches of Mr. Murray, and of his assistant, Mr. James B. llowloy, have however led them to adopt a very different view, which is set forth in ?n It ^ 1: .i ! 1 ^H' ; ' ^M M i i It '^H' ; 'fll ' 196 E. spp:cial report, t. STicnitY hunt, 1875. the report of tlie latter, dated March, ISTo, approved by Mr. Murray, and published as a supplement to his own i-e- port, in the same year. The conclusions from Mr. Ilowley's examinations on the east shore of Port-a-Port Bay, about sixty miles southwest of Bonne Bay, are that the lower paleozoic formations of the region, supposed to include Potsdam, Calciferous, Levis and Sillery, are arranged in a series of sharp folds, ranging N. 22° E. ; *'the whole mass of strata having, towards the close of the later deposits, or subsequently, been affected by vast igneous intrusions, and become much dislocated by a set of great parallel or nearly parallel faidts, the general trend of which is northeast and southwest. At the summit of the whole series is a great volume of igneous and magnesian rock, consisting of various diorites, serpentines and chlorites, which our evidences seem to indicate to be lapped over the inferior strata uncon- formably, and to come in contact with different members at different places." § 378. In the succeeding pages of the report, as in tlie geological map of Newfoundland, published in 1876, tliis whole magnesian series is designated as "serpentines," or "ophiolites," and we read, "further to the northward, the sandstone group was invariably seen to pass below the ser- pentines, whi<^h were wrapped over the former in a confused and irregular mass, the points of contact differing at diifer- ent jjoints in such a manner as (^ould only be accounted for by supposing the ophiolites to be unconformably related." (Report on the Geol. of Newfoundland, 187o, pages 52, 54). § 370. In a note affixed to Mr. Milne's paper on the geology of Newfoundland, inthedeological Magazine for June, 1877, (page 256), Mr. Murray quotes the language of the first of the above extracts, as expressing his latest opinions on the relations of the rocks in question. He says, moreover, of the Sillery sandstone, "while we find it to succeed the Levis forniati(m with perfect regularity, although with numerous folds and twists, in every case it seems to pass below the serpentines, wherever a contact is seen, and in every case to pass below them unconf ormabl y. ' ' He further concludes from the presence, in the vicinity of Poit-a-Port Bay, of MURRAY ON THE GEOLOGY OF XEWFOUXDLAXD. E. 197 comparatively undisturbed beds holding a fauna of Trenton, and perhaps of Loraine age, that "the great igneous in- U'vis ln'ou8 IV the case hides Iv, of trusion * * * must be nearly at the age of the Chazy, or perhaps later : that it has been the metamorphosing agent ; and that the altered strata, consisting of chloritic slates, serpentines, melaphyres, diorites, etc., belong to a horizon somewhere intermediate between the Chazy and Hudson River [Loraine] group." § 380. The observations made at Bonne Bay, (§ 218), where, on the northwest side of a hill of these serpentinic strata, the Sillery sandstone, overlying conformably the fossiliferous rocks of the Quebec group, is seen to dip southeastwardly, as if to pass beneath the crystalline series, is cited by Mr. Howley in favor of the above view. 'No reference is how- ever made to the different condition of things described at Pistolet Bay, (§219, 227,) where, on the contrary, or south- eastern side of a similar area of crystalline rocks, the Sillery sandstones are said to be found, occupying a breadth of some miles. Their attitude in this localltv is not recorded, but a little further south, along the eastern coast, the same sandstones appea. in the island of St. Julien, succeeding the serpentinic series, though without visible contact, and dipping away from it to the southeast. § 381. The facts already set forth show that neither the view of Logan, nor the later one put forth by Murray and his assistant, is admissible, but that the crystalline rocks, formerly described as belonging to the "altered Quebec group, " like the similar rocks of the coast of New Brunswick, and Massachusetts, belong to a series older than the uncrystalline strata known as the Quebec group. Upon this ancient crystalline series, there was deposited uncon- formably the Sillery sandstone, succeeded by the Lauzon and Levis divisicms. In the interval between this last and the Trenton age, came a time of distuibance, producing great northeast and southwest folds and dislocation^, with overturns to the northwest, and upthrows on the southeast side. As a result of these movements, the Cambrian strata on the northwest side of the belt of older crystalline rocks are very generally found to be inverted, and. in parts, are ■n m ii fit ■: Is I i I ■■ ''1 I I 198 E. SPECIAL REPORT. T. STERRY HUNT, 187o. over-ridden by the pre-Cnmbrian strata, beneath which they now appear to pass unconformably, as in the sections at Port-a-Port, Bonne, and Pistolet Bays, already de- scribed, where tlie existence of snch dislocations, with up- throws in the southeast side, has been pointed out (§ 219). The structure above described is well known to be almost universal along the whole northwestern bordei- of the At- lantic mountain belt, from Canada to Alabama, and has been described at length by various observers (§ 15, IG, 71- 81, 177—179). § 382. It may be added that the investigations of the geological survey of Canada, during the years 1870 and 1877, have, according to the director of the survey, demon- strated the correctness of the view, so long maintained l>y' the writer, that the crystalline rocivs of the Green Mount- ain series belong to a more ancient system, Avliich underlies unconformably the uncrystalline Cambrian sediments of the Quebec group. The unpublished observati(ms of Prof. AVilliam B. Rogers upon the similar strata in Virginia are to the same effect, and the writer is permitted, in this connection, to print the following extract from a letter addressed to him by this eminent geologist, and dated Boston, June 8, 1877 : § 3S3. "The sections which I had the pleasure of showing you lately, illustrating the position of the Lower Cambrian beds (our Primal conglomerate, etc.) in their contact with the crystalline and metamorphic rocks of the Blue Ridge in Virginia, form part of a series embracing the results of some forty transverse explorations, made during and since the Virginia geological survey, at nearly er[ual distances a^'ross the chain, from Harper" s Ferry to the North Carolina line. In many of these sections the unconformity of the Cambrian upon and against the crystalline and metamorxiliic rocks is unmistakable and conspicuous ; the lower mem- bers of the Primal being seen to rest on the slope of the Ridge, with northwest undulating dips, central mass of the mountain. But even in these instances it is, I think, not difficuU to discern the true relations of the strata. As interest! iiu- examples of the phenomena referred to, I would mention the sections ex- posed at Vestal's, Gregory's. Snecker's, and Manasses Gaps, and Jeremie's Run, in the northern part of the Blue Ridge ; and at Dry Run, Turk's, Tye River, White's, James River, Point Lookout, Fox Creek, and Whitetoi) ^fountain Gaps, in the middle and southwestern piolongation of the logical relations with the brown hematites of the region, s(mie of which belong to the same Primal slates. These ores, which I believe to come fnmi the alteration of deposits of car1)onate, and, in many cases, of sulpliuret of iron, oxydized in sit'O,, are, in certain deposits of the re- gion, interstratified with crystalline magnetic and specular oxyds ; the whole being imbedded in the clays which have resulted from the more or less complete decomposition of the enclosing crystalline rocks." § 394. The micaceous substance which makes up a con- siderable part of the residue remaining after the decay of these schists (which rre often impure limestones,) has been found by Genth to have, in many cases, the composition of a hydrous non-magnesian potash-mica, referred by him to the species damourite. This however is not always the case, since both talc and chlorite are found in the Primal slates of the Cornwall mine, and chlorite, with garnet, in those of the Jones mine. Tlie latter moreover includes beds of an apparently decayed rock, which has been mined as an ore of copper, and consists in large part of a soft pale green mineral, in minute scales, resembling in aspect the hydrous mica above mentioned. Analysis however sliows it to be a li\ drous silicate of alumina, ferric and cupric oxyds, and magnesia, constituting a kind of copper-chlo- TALCOSE ok NACKEOCS SLATES. E. 205 the imal in ides ined nnle tlie ows pric hlo- rite, wliicli has been described by the author as a new spe- cies, under the name of venerite (Trans. Amer. Inst. Min- ing Engineers, lY, 32G.) § 39.5. The soft and unctuous schists of tlie Taconic were by Emmons designated magnesian slates or talcose slates, and the hitter name was also given to the somewhat similar schists found in the Huronian series, with which the former were generally confounded, although Emmons clearly distin- guished between the talcose slates of the Taconic, and those of what he called the Pi'imarv rocks. In 18.j5, the writer, having examined many oL' the talcose slates, from both se- i-ies, announced that they contained little or no magnesia, and were essentially hydrous silicates of alumina, belong- ing to the class of minerals represented by i)yropliyllite, pholerite, etc. To avoid the perpetuation of an error, he therefore prf)i)osed for these unctuous aluminous schists, in allusion to thek pearly lustre, the name of nacreous slates (Amer. Jour. Sci., II. xix, 417). § 89G. Emmons soon after described, in IS^G, the occur- rence of a soft compact mineral, locally known as soap- stone, which, according to him, occurs in many i)arts of North Carolina, interstratiJied witli the quartzites, talcose slates and limestones of the Lower Taconic series, in wliicli it "takes the place of steatite." This substance, which is white, or greenisii-w^hite in color, and sometimes holds crys- tals of magnetite, having been analyzed by Dr. C. T. Jack- s(m, was I'cmnd to be essentially a hydrous silicate of alumina, and by him referred to agalnuitolite, a name which was adopted by Emmons. (Geol. Midland Counties, N. Car., pages 52-oo, 127, and Proc. Bost. Soc. Nat. Ilist., VI, 33). Brush, in 1858, showed that wliat had hitherto been called agalmatolite, was really l)ut a compact pyrophyllite, which he correctly described as an aluminous talc. (^xVmer. Jour. Sci. II. xxvi. 08). § 397. It thus ai)pears that besides the foliated magiiesian minerals, talc, chlorite and venerite, all of which are occasion- ally met with in the Taconic schists, these are various micaceous hydro-silicates of alumina, including pyroj)hy] lite and damourite, which eithei- jMire. or mingled wiili i|iiait/.. M I : 2(J6 E. special report, t. sterry hunt, 1875. I enter into the composition of the so-called talcose-schists, originally designated nacreous slates by the writer, and now frequently spoken of as hydro-nuca slates. § 398. As regards the relation of the Lower Taconic series to organic life, it is well known that the Primal white sand- stone, in various localities from Massachusetts to Tennessee, contains a form described as Scolithus, of which the history has been given at length, (§ 200). In a communication by the writer, in the Proceedings of the American Association for the Advancement of Science for 1870, (page 208), it was stated that Prof. Prime had lately found in the Auroral limestone of Pennsylvania, besides an undescribed Lingula, certain casts which Dr. Torell, after examination, regarded as generically identical with those found in the Eophy ton- sandstone of Sweden, and supposed to belong to a radiate animal, to which he had given the name of Monocraterion^ (§ 250). It is not improbable that these casts in the lime- stone in Pennsylvania may be due to the same organism which has produced the Scolithus of the Primal sandstone. The relations of this Primal and Auroral series, both to the Eophyton-sandstone of Norway, and to the series of lime- stones, talcose-slates and quartzites which are fountl in southern Norway, at the base of the Cambrian series, and are by Kjerulf named Lower Taconic, (§ 257), are subjects for further inquiry. Under the name of PalccotrocJi is, Emmons, in 1850, de- scribed what he conceived to be a silicious coral, found in the quartzites of the Lower Taconic in Troy, Mt)iitgomery county. North Carolina, but there does not seem to be any good ground for regarding it as of organic origin, (Geol. of the Midland Counties of N. Car., page 00; and Chem. and Geol. Essays, page 411), § 399. We have given reasons for regarding the Lower Taconic, or the Primal and Auroral strata of the great Ap- palachian valley, as the equivalents of the similar series in southern New l^runswick, (^ 344), and of the Hastings series in Ontario, (§ 331, 341), with its Scolithus and Eozoon. While it has been shown, in a preceeding chapter, that the Upper Taconic includes the organic remains of the European Cam- BLUE KIDGE IN NORTH CAROLINA. E. 207 brian, at least as low as the Menevian, it is by no means certain whether the Lower Taconic series is to be regarded as the equivalent of the still lower beds of the Cambrian of Great Britain and Sweden. In this uncertainty it is deemed well to preserve for this series the original name of Taconic, or better, Taconian. (Proc. Bost. Soc. Nat. Hist., XIX. 278). § 400. Some recent observations by the writer on the crystalline rocks of the Blue Ridge, are given in a commu- nication to the Boston Society of Natural History. (Pro- ceedings, etc., XIX, 277.) Attev noticing the presence of rocks both of Montalban and Iluroniau ages, on the line of the Baltimore and Ohio railroad, (the latter near Harper's Ferry,) and the existence of Laurentian gneisses at Bell- isle, near Richmond, Virginia, some account is giv'en of the crystalline rocks seen in a section across the Blue Ridge, in Mitchell county. North Carolina. "The gneisses of Roan Mountain, and similar rocks at its western base, which inchule the great masses of mag- netite, are Laurentian, but indications of a belt of Iluronian schists, associated with specular iron-ore, are found on the western flank of the mountain. To the eastward, the Lau- rentian rocks are succeeded by a great breadth of thin- bedded gneisses, with highly micaceous and hornblendic schists, referred to the Montalban series, in which is included the narrow belt of dunite, or olivine rock, found near Ba- kersville. Tliesc Montalban stnita are intersected by nu- merous endogenous granitic veins, wldcli are largely ex- jiloited for mica, and yield, moreover, line cleaval)le masses of orthoclase, and of albite, together with beryl, apatite, samarskite, and autunite. The rocks of this series, often deeply decomposed, were found to occupy the greater part of the ';ountry, as far east as Salisbury, interrupted, how- ever, near Statesville, on the Western North Carolina rail- road, by gi'anitoid gneisses, which have th(3 characters of Laurentian." (For some notice, by the writer, of the metal- liferous veins in the Montalban rocks of the Blue Ridge in Virginia, North Carolina and Tennessee, see Transactions Amer. Inst. Mining Engineers, II, 123, and Chem. and rfcoj. Essays, page 217.) w 208 E, SPECIAL UKPOIiT. T. STEUPvV HUNT, 187o. § 401. "The belt consisting of granular quartz-rock, with limestones and hydrous mica-slates, which was seen at the eastern base of the Blue Ridge, on the Catawba river near Marion, North Carolina, has all the characters of the Lower Taconic, to which it was long since referred by Em- mons. Portions of this quartzite are thinly bedded and flexible, constituting what is known as itacolumite. It is regarded by the writer as identical with the Primal white sandstone of Pennsylvania, whi(;h, with the Auroral lime- stone, and its interstratiiied and overlying unctuous schists, and the succeeding rooling-slates, constitute a distinct geo- logical horizcm." § 402. In his rept)rt on the Geology of North Carolina, in IBTf), and in the colored geological map and sections ac- companying it, Prof. Kerr has included the whole of the crystalline stratified rocks of the State under two heads, Laurentian and Ilurouian. The former of these, both in the text, and in the legend of the ma]), he divides into Lower and Ui)per Laurentian, though in the ac('omi)anying colored sections, the Lower division is called "granite." The name of Upper Laurentian, originally given by the geological survey of Canada to an entirely different group of rocks, the Noiian or Labradorian, is by Prof. Kerr ai)plied to the series of gneisses and micaceous and horn- blendic schists, (with included beds of chrysolite-rock,) which is that described by the writer in the above section, as the Montalban, of which it has all the characters ; Avhile the rocks of the Roan Mountain, called by Prof. Kerr, Lower Laurentian, are, as already stated, true Laurentian. ^ 403. Under the head of Iliii'onian, Prof. Kerr informs us he has included the Taconic series of Emmons, including the (jiiartzites witli the so-called Falcmtroclih, the itacol- imiite or iiexible sandstone, the hydrous mica-schists, the argillit(^s, often ])lumbaginous, and the pyrophyllite beds, togvt her with the granular limestones and marbles, often ac- <'oMi[)aiiied by limonites. The qiuutzites of this series, like those of the same liorizon in Pennsylvania, often abound in magnetic and specular iron-ores, and sometimes jiass into a speculai- schist or itabirite. This series is de- PUK-CAMBKIAN AGE OF TIIK I5LUE KIIM'.E. E. 'iOi) scribed by Prof. Kerr ;is resting upon the Uppei* Lauren- tian, (Monta'ban) and in part made up of its ruins, lie has indicated not less than live parallel belts of tJiese so- called lluronian rocks, stretching from northeast to south- west, in Xorth Carolina, one of which includes nieTaconiiin rocks noticed by the writer :it the eiistern base of the Blue Uidgc, in th(^ section described above. It remains to be de- teiinined Nvhere, and to what extent, true lluronian i-ocks occur within the limits of North Carolina, but it appears not improbable that some of the more massive portions of the lluronian may be included in the rocks, which under the names of greenstones and I'eldspai'-porpliyries, aresaid- by Prof. Kerr, to occur in parts of the so-called Upper Lau, rentian areas. § 404. AVe may in this j^lace notice the vi- s of Prof. F. Bradley, who, arguing chieily from a supposed i)arallelisui between the various groups of crystalline rocks and the dilferent paleozoic formations of the Champlain divisi(m, has recently been led to put forth anew the old hypothesis of the paleozoic age of the crystalline sti-ata of the Atlantic belt, and to suggest that the l>liu' IJidge, in North Carolina and 'i'ennessee, consists of altered Cambrian and Siluro- CVunbrian rocks (Amer. Jour. Sci. Ill, ix, '27i),']7()). To this hypothesis, a conclusive answer is furnislied by the observations of W. B. Rogers, and of Fontaine, already quoted, as to the rehitions of the basal paleozoic rocks to the crystalline schists, and by the express declaratiou of tlie latter that certain of these, desci'ibed by him as aru,il- lites, were in their present condition before the Pi'imordial (either Taconian or Cambiian) period, (ibid. Ill, ix, 'U)7) as apjx'ars from the fact that fragments of these are found, together with feldspathic debris, in the Primordial con- glomerates. From this, he concludes that the crystallim^ rocks of the Blue Ridge foruied the southeastern boi'der of the ])aleozoi(; sea; while Bradley, on the coutrary, imagiues these same rocks to be themselves ])aleozoic strata, which were uplifted and altered after the close of the pahM)Zoic period. The observations of Fontaine ai'e couliruied by those of the writer, who has found in southwestern Wv- 114 K.l ^ 210 E. SPECIAL REPORT. T. STERRY HUNT, 1875. ginia, pebbles of gneiss and of mica-schist, apparently Montalban, in tliese basal conglomerates (Harper's Annual Record, 1875, pages c — cii). § 405. We have already adverted to the fact that the five great groups of crystalline stratified rocks, constituting as many distinct terranes — Laurentian, Norian, Iluroiiian, Montidban and Taconian, necessarily have, notwithstand- ing their differences, certain lithological resemblances with each other. All of them include quartzites, and crystal- line limestones, in which latter certain mineral silicates, such as serpentine, hornblende, and micas are occasionally met with. It is in those alumiuiferous rocks which are without lime and magnesia, that are found the essential and characteristic differences, and these depend upon the principle, set forth in detail by the writer, in 18G3, of a pro- gressive diminution in the proportion of the alkalies to the alumina, (Chem. and Geol. Essays, page 27) as we pass from the older to the newer geognostical groups. In accord- ance with this, the feldspars, orthoclaseandalbite, gradually disappear, being partially or wholly replaced by silicates like muscovite, damourite and paragonite, and finally by andalusite, fibrolite, cyanite, stauroliteandpyrophyllite. These various silicates are scarcely known in the Lauren- tian and Norian, though they are represented to a limited extent, by certain quartzose mica-schists, in the Huronian. In the Montalban, they appear to a considerable extent, and have their most complete crystalline development in cer- tain beds in that series, although oithoclase still predomi- nates in the associated gneisses. § 40G. In the Taconian rocks, on the contrary, the feld- spars are but rarely and excej)tionally developed, while hy- drous silicates of alumina, such as damourite and paragonite, or pyrophylite, which is destitute of alkali, abound, and either alone or mingled with quartz, or with limestone, form great beds in the series, in which also are found stauro-" lite, chiastolite and cyanite, though generally not so well defined as in the ;Montall>an, which is easily distinguished from the Taconian by its great development of strong mica- scliistSj well-marked gneisses, and blackish hornblendio RELATIONS OF TACONIAIN' TO PALEOZOIC TIME. E. 211 cer- lomi- ,Md- liy- and Ifoim luiro-' well [shed liiica- Midio schists. (Chem. and Geol. Essays, page 244). It is by a misconception that some have been led to regard the pres- ence of staurolite, cyanite and andalusite, as exclusively characteristic of the Montalban, a proposition nowhere maintained by the writer, since, although they have not been found in the oldest terranes, these mineral species have long been known to occur, in many localities, in the Tacon- ian schists. § 407. The question has arisen wheth(n' these crystalline rocks of the Taconian series, occupyinr i\ position between the Montalban below, and the recognized Cambrian above, are to be regarded as «jozoic, or as paleozoic. In the lan- guage used by the ^vTitei, in 1876, in answer to this question : " It will be found as difficult to draw the line between the eozoic and paleozoic, as it is to define that between the mes- ozoic and tlie paleozoic, on the one hand, or the mesozoic and the cenozoic on the other. There are no hard and fast lines in nature ; breaks are local, and there is nowhere an appa- rent hiatus in the geological succession, which is not some- where filled." Referring to the Liiigulu of the Auroral limestones, it was then suggested "that this seemingly imperishable type of brachiopods may serve, like the rhizox^ods, represented by Eozoon, as a connecting link be- tween eozoic and paleozoic time." (Proc. Assoc. Advan. Science, 187G, pages 207, 208). § 408. We have already noticed in § 119 — 122 some of the various and contradictory liypotheses i)at forth \\ itli regard to the age of the Taconian or Stockbridge limestones, as dis- played in western New Enghmd. According to II. D. Rogers, they, like the Auroral limestone of Pennsylvania, are of the age of the Calciferous and Chazv of the New York series, while by Adams and others they have been supi'josed to be either Lower Ilelderberg or Dcnonian. Ma- ther, and later Dana, have maintained that they are of Trenton age, while Logan, in his geohigical niaj), published in ISGG (§ 44) has represented them as the Levis division of the Quebec group, or Upper Taconic — the original charac- ters of the linu^stones, in all cases, being supposed to have been greatly modified by a subsequent process. Of these r i ' J 212 E. 8PECIAL IIKPOKT. T. STERRY IIUXT, 187o. four irreconcilable views, each one in its turn, has been plausibly defended upon the ground of apjiai'ent sui)erpo- sition to, or of association with fossiliferous strata of dif- ferent horizons, in one or more localities. § 400. It has long been known that the more ancient folded and faulted strata, along the Atlantic belt, include jMU'tions of newer formaticms, of various ages, and nioi-e- over that tiue natural order of the strata is so generally in- verted, that the newer formations pass, or seem to pass, beneath the older. Of this, a marked example has been given in § 2132, where, in Fandiam, in the x>rovince of Que- bec, the strata holding a Hiluro-Caml)i'ian fauna, were as- signed a position at the base of the Quebec group. The observations of Wing, and of Billings, have shown the ex- istence of siuiilar examples in western Vermont (§ 20.")) which have more recently been discussed bv J. D. Dana. The similar strata on the eastern side of the Green Mount- ains, in northeastern Vernu)iit aiul Canada, referred to by Logan (§ 331), are accompanied by fossiliferous strata of Lower llelderbergor Devonian age. P^urther southward, in the valley of Virginia, Devonian and Carboniferous strata become involved in these disturb- ances, and are seen to dip at high angles to the southeast- ward, apparently passing beneath the Taconic or Auroral limestones. (Comjiare Emnums, Amei-. Geol., II, 04, and Lesley, Proc. Amer. Philos. Soc, XII, 480). § 410. The argument of those who ignore these facts of structure, and adopt the liyi)otliesis of metam()ri)hisui, may thus be stated: Fossiliferous strata included in folds, or in faults, are supposed to lix the age of the entire series in question, while the absence of organic remains from other parts of the section is accounted for by the assumed meta- morphosis of these parts. The faith of some believers in this hypothesis has frequently led them to mistake obscure and doubtful markings in (Tystalline rocks, for vestiges of organic^ life. A sti'iking exauiple of this is alfonled by the supposed brachiopods and tiilobites, upon which it was at one time attempted to establish the Silurian age of the White Mountain gneisses and mica-schist^ (§ 123). DANA ON THE TACONIC QIAKTZITES. E. 21:3 in lure of Ithe at Ithe § 411. The late notes of Dana on tlie geology of Vermont contuin some observations on this point, which are not the less instructive that they come from an extreme advocate of the iiietamori)liic hypothesis. Describing a quartz rock, which in New Haven, Vermont, is int(?rstratilied in lime- stones supposed to belong to the Taconic- series, he says: "The (piartzite is in most parts a little slaty in sti'ucture, and in Hunted ptntions, a shining grayish-black slate. In places over it areareas of sub-concentric condioidal lamina- ti(m, looking somewhat as if <'x:imples of the tiow-and- pluuge structui'e, but more probably a result of concreticm- ary consolidation. To the latter cause, I attribute some forms that looked exceedinglv like casts of a Phiivolo- HKiria and a Murdiisonia, and of a valve of Orthis hjnx. Others of these imitative forms, over the surface, were serai- cylindrical and chambered, as if worn casts of long cri- noidal stems, yet having the chambers too large and irregu- Lir for any known crinoidal forms. These simulations of crinoids may also be due to a concentric structure in the slaty portion of the rock, yet how, it is not easy t(j unchH'- stand." (Amer. Jour. Sci. Ill, xiii, 409). § 412. Dana has, in this connection, given a figure of natural size, of a portion of one of these chambered cylin- ders, which had a total length of twenty-five centimeters. It is represented as divided by transverse sei)ta of about one milliuK^er in thickness, into ('hambers having a length of three centimeters, more or less, and a breadth of six cen- timeters. The walls of the cylinder, in the drawing, are not distinguished from the enclosing rock. The figure bears such a close resemblance to the transversely waved or grooved casts of so-called Scolithus from the Primal sand- sttmes of Pennsylvania, (^ 206, 208), which probably I)elong to the same horizon, that it seems highly jirobabhi that these hollow casts mav be due to the same cause, and tluit they are of organic origin. § 413. It is not improbable that the Taconian rocks may include other forms than Scolithus and Monocraterion, and the undescribed lingultjid shell. In their study, however, it is necessary to l)e\vare, on theone hand, of mistakingsuchcon- I 214 E. SPECIAL REPORT. T. STERRY IITJIS'T, 1875, i * ; i_ ■ 7? ■i it 1 ■ 7 cretionary miirkings as tliose already mentioned, for organic remains, and on the other to avoid the error of referring to these older rocks, what are perhaps portions of newer strata resting npon them, or involved in their folds or dislocations. The rocks thus brought together may differ so widely in Lithological characters that it is easv to discriminate be- tween them, but in other cases the task is much more diffi- cult, as in the example of some fossiliferous Silurian beds in southern New Brunswick, made up almost wliolly of the disintegrated Huronian greenstones, in the midst of which they were deposited. Another example is that of the Trenton limestones of Hastings county, Ontario, which resemble so closely some of the bluish-gray enrthy beds of the underlying Taconian, that it is very easy to mistake the one for the other (§ 333). The difficulty of distinguish- ing between these two formations would be greatly en- hanced were the newer rocks involved with the older in a se- ries of folds, inversions and dislocations, as in the case in the Appalachian valley. When we add to this, the of jirocess decay, which has converted the slaty and impure i:)ortions of the Auroral limestone, for considerable depths, into a soft and yielding material, it is evident that the localities of fossiliferous limestones in such a region should be scanned with the gi'eatest care. § 414. Prof. Prime, in a late paper on the limestones of this valley, in Lehigh and Northampton counties, Pennsyl- vania, after mentioning the Monocraterion and Lingula, al- ready pointed out (§ 398,) each of which has been found only at one locality in Lehigh, notices the occurrence, in the same county, of a single 0?i7ioceras, too imperfect to be de- termined, and a specimen of Eriomplialus. Both of these are supposed to occur in the Auroral, wliich however has not yielded a single organic fossil in Northampton county. Overlying the Auroral, in these counties. Prof. Prime finds, at intervals, portions of an argillaceous limestone, containing in abundance the characteristic forms of the Trenton, such as CJicctetes lycoperdon^ and Orthls pecilnella^ withcrinoi- dal stems. This limestone is said to differ from the Au- roral in being ' ' more compact, and not at all crystalline, and RELATIONS OF THE VAIIIOUS EOZOIC SEIIIES. E. 215 of a gray-black color." It is clescri])ed as "apparently con- fomiable" with the Auroral, (Proc. Amer. Pliilos. Soc, Dec. 21, 1877). § 415, From his own observations in this region in 1875, the writer was led to believe that, besides the Auroral limestones, with their succeeding argillites, and the uncon- formably superimposed Silurian (Oneida) conglomerates of the North Mountain, there are, to the west of the Lehigh River, portions of two intermediate formations. One of these, marked by red-colored sand>it()nes, conglomerates and slates, appears to be the same w itli the Upi)er Taconic or Cambrian belt, which has been traced by II. D. Rogers, Mather, Emmons, Logan and the writer, with some inter- ruptions, from New Jersey to Canada, along the great Ap- palachian valley (§ 74, 03-90). The other is an impure black earthy limestone, becoming, in parts, a soft thinly- laminated llag-stone, which was seen lying, at moderate an- gles, above the blue limestone of the valley, not far from Copley, and was then supposed to belong to a different se- ries. It is apparently the same with the Siluro-Canibrian (Trenton) beds, recognized by Prof. Prime in that vicinity. § 410. The evidences adduced in these pages furnish abundant proofs of tlie unconformable superposition of the Iluronian to the Laurentian series, while the contrast be- tween the highly disturbed condition and nearly vertical attitude of the fomier, and the broad folds and gentler dips of the Montalban, in so many regions, have long since been urged by the writer as evidences of a probable stiatigrajihical unconformity between the two. As regards the Taconian series, its apparent relations to the Montalban in Ontario, Maine, and North Carolina, and the frequent absence of the latter series where the Taconian rests unconformably upon Laurentian or Iluronian, lead us to conclude to a want of conformity between Mcmtalbau and Taconian. In like man- ner, the absence of the Taconian at the base of the Cambrian, which, in so many jilaces, reposes directly upon the Lauren- tian, or upon the Iluronian, indicates a great stratigraph- ical break between Taconian and Cambrian. § 417. The evidence of various periods of disturbance, Jil :. Hi 21(5 E. SI'KflAL UKI'OFM'. T. STKIMJV IirXT. 1875. IIIW' ni;iik('(l by discordanc*', in the paleozoii^ strata alon^ the Atlantic belt, have been pointed out in § 241, 242, where reasons arc* also <5iveii for b<»lievinjjj in tlie existence of anotlier such ]»ei-iod between the Cambrian and the Silnro- Canibrian (Ticnton-Loraine sei-ics). ^fr. N[uiiay's obser- vations near Port-a-Poit Hay, in Newfoundland, furnish a fiiitlici- proof of this. While the Cambrian rocks are there affected by sliarp folds and gi'eat dislocations, he f'^ls the limestones holding' a Siluro-Cambrian fauna, near o be "('(►mparatively undisturbed," ami coucludes ri;4"hi.y, that the movement whi<'h brouuht thcci-ystalline rocks into their position of aj)]>ai('ntly unconformable superposition to the foi'incr, was intermediate between the two ]»(M'iods named. AVhile w(^ dissent fioni his view of tlui orii^in of these <'rya- talline rocks, and believe that the i)resent geognostica I re- lations ai'e due to the disruption and ujilifting of solid rocks of a more ancient system, ratiier than to an eruption of igneous matter, about " the age of theCliazy," the evidence, in either case, sIkjvvs a pei'i(/d of great disturl)ance of the ('and)iian sti'ata in the interval above indicated, the natural resiUt of which would be a want of couformitv ^ ween these and the succeeding Sihiro-Cambrum. ,^ 377 5^ 418. Before passing to the considei'ation of the gvology of Lake Superior, we may notice the presence of Iluronian rocks in Newfoundland. In his report for 18G8, Mr. Mur- ray announced the existence of a series of liighly contorted strata, overlying the Laurentian, and tluMnstdves overlaid unconformably by nearly horizontal sediments, the latter containing, in their lower portions, a Menevian fauna, and higher up, the forms of the Potsdam or Lingula llag-group. This mtermediate series was declared to have close resem- blances with the Iluronian of the great lakes, to which it was at once referred by Mr. Murray. The name of Cam- brian, which he at first used for this series, as synonymous with Iluronian, he has since very properly rejected. (j5 359). According to Di'. Dawson, who has examined col- k^cticms of these rocks, they are very similar to the Iluron- ian of southern New Brunswick, so that we are constrained to look upon them as a porticjn of what has been called in IiriJoMAN KOCKS IX XKWror.MU.AM). K. '2\7 noitlnvt'sfern Newf(mii(U:iJi(l, t\ut "jiUj^ivd Quebec groui),'" whicli we have already relenvd to the Iluroiiian seiies. § 411). This lltirouiaii series, as described by Mr. Murray, is loiind in the soiitlieasten |tart of Newi'omidiaiid, and makes lip the <'hier jtait of the peninsula ol" Avaloii. Tlie strata are descrilted as consisting', in the lower poUions, of greenstones and slaty rocks, often epidotic and chloritic, with qiiartzites, coni!,lonierat<*s and jiispeiy petrosilex. These crystalline rocks have a thickness of many th(»usand feet, above which, in ai>i)arent conformity, are several thousand fe<'t of sandstones and argillites, liol'i(J(ll(i and AvcnicoTiUs^ the whole overlaid unconforniably by the Menevian strata. ^lej)ort on tlie Geology of Newfoundland for 1{S<5S, i)age 12; (.'hem. and Geol. Essays, page 410, and Geol. Magazine for 1877, page 25;]). As evidence of the gi*eat erosion to which this region was subjected in i)re-Cambrian times, Murray notes that the nearly horizontal paleozoic strata above named an.' found extending alike over the outcrop of the Laurentian. and over the basal beds '>C the nearly vertical lluronian seric^s. § 420. lluronian ro'-ks were noticed in 1870, l)y Mr. Rich- r.nlson, lying to the , Ttli of Luke St. John on the Sague- nay, and near Lake M.-itassini, where they occup}'^ a cpi(lotic strata, rooling-slates, steatites, chromiferous serpentines, magnetite and (.'oi»i)er ores. (Geol. Report for 1870, page 292, ami for 1872, page 115). § 421. That these various areas of lluronian rocks, whether found in the Atlantic belt, or lying to the north and west ^i- 218 E. spp:cial report, t. sterry hunt, 1875. of it, formed parts of a great and widely-spread eozoic formation is clear, and it is a question whether i)ortions of it may not exist in the Adirondacli region. Tlie writer has found in the drift, in the rear of Westport, in Essex county, New York, numerous fragments of Iluronian schists, which may reasonably be supposed to have come from the mount- ninous region of the interior. § 422, In tliis connection it may be permitted to call at- tention to some notes by Major T. B. Broolvs, published in 1872 (Amer. Jour. Sci. Ill, iv, 2?) with the title, "On cer- tain Lower Silurian Rocks in fet. Lawrence county. New York, which are probably okler than the Potsdam Sand- stones." Under this head ho lias described certain strata found with the specular iron-ores of the Keene and Cale- donia mines. Immediately under the ores, is said to be a considerable thickness of a greenish schistose magnesian rock, described as serpentine by Emmons, beneath which is a mass of crystalline limestone, several hundinnl feet thick, which, like the serpentine, is graphitic, and moreover contains crystals of bronze-colored mica. It includes in its lower part "irregular beds or veins of granite," and is underlaid by a well-characterized gneiss, with which it is conjectured to be unconformable. Interposed in this limestone is a thin bed of sandstone, and a similar sandstone, sometimes conglomerate, and re- sembling the beds of the Potsdam, overlies the iron-ore. These strata, including the great mass of limestone, are thrown into folds with a northeast and southwest strike, and often dip at high angles. They have all the characters of the Grenville series of the Laurentian, from which there does not appear to be any good reason for separating them. The associated sandstone beds recall the similar case in Bastard, Ontario, described in § 28G. § 423. As regards the newer series of crystalline rocks, found by ^lurray to overlib the ancient gneisses around Lakes Superior and Huron, we have seen that Logan, for a long time, maintained that they are the stratigrajihical equivalents of the so-called Volcanic formations of Lake Superior, wliich are characterized by amygdaloids and sand- CUPKIFEROUS KOCKS OF LAKE SUPERIOR. E, 219 Stones, with native coi)per. In the Esquisse Geohnjique, in 1855, as well as in the geok)gical map accomi)anying it, the two series are included under the fommon name of Hurt)n- ian, then first used. A similar view was defended bv Rivoc and bv Dawson, in 1850 and 1857, and tlie considerable mineralogical and lithological dilVerences between the two groups were ascribed to the greater amount of alteration or metasomatic change which the former had undergone, (§ 141, 142, 152-157). § 424. In 1857, however, J. D. Whitney, while denying the distinction between the Iluronian schists and the un- derlying gneisses, both of which he included under the common name of the Azoic system, declared the Volcai}ic or native-copper bearing group to be entirely distinct from the Azoic, and superior to it (§ 158-160). This latter con- clusion was confirmed by the examinations of Murray in 1859, and 18(30, (§ 102) and in 1803, in the Geology of Canada, the name of Iluronian was confined to the crystalline schists which make the upper part of the Azoic system of Whitney, and, from their metalliferous character, were now sometimes designated the Lower Copper-bearing series. The Iluronian, on Lake Superior, was now said to be "un- conformably overlaid by a second series of copper-bearing rocks," which was the Volcanic format ion containing native coxiI)er (loc. cit. page 07). § 425. As regards the age of this Upper Copper- bearing series, as it were now called by Logan, we have seen that Whitney declared that it ""cannot be separated from the Potsdam sandstone with which it is associated." To this horizon he referred the nearly horizontal sandstones of the region, supposed to be the same with the red sandstones found at Sault Ste. Marie, and often called the St. Mary's sandstone. The observations of Mr. Murrav in 1859, had however slown that these sandstones, to the southeast of SaultSte. Marie, are overlaid, conformal)ly, by a fossiliferous limestone belonging to the base of the Trenton, from which Logan concluded that "' the underlying sandsti )nes and < )tlier rocks constituting the Upper Copper-bearing series of Lake Superior, may thus represent the Chazy, Calciferous and I i 220 E. SPECIAL REPORT. T. STERRY HUNT, 1875, Potsdam fornKitions, and be equivalent to the Quebec group, and tlie black slates and limestones beneath." This sugges- tion was put forth at the end of 1800, in a letter to Barrande, already cited (^5 201). § 420. A little later however, in Chapter V of the Geology of Canada, Logan gave reasons for believing that these sandstones, then regarded as of the age of the Chazy or St. Filters sandstone (jj 27o, 270), overlie unccmi'orinably the ti"ippean and conglomerate rocks with which they had been united by Whitney, so that "the coj^per-beai-ing portions of the Lake Su^jerior rocks might reasonably be consider(?d to belong to the Calciferous and Potsdam foiniations " (loc. cit. j)age 80). Subse(piently, in discussing the Que- bec groux^, and the crystalline rocks of the Green Moun- tain range, then supposed to form a i^art of it, it was said : •'This whole series of rocks however occupies a strati- graphical place which brings it to the horizon of the Upjjer Copper-bearing series of Lake Superior.'' (Ibid, page 2:^0). In accordance with this conclusion, the Upper Copjier-bear- ing I'ocks were, in the geological maps published by Logan in IS(J4, and in 1800, (^ 44), rei)resented as l)el()nging to the Quebec group, while the St. Mary's sandstone was referred to the Chazy formation. § 427. Reverting now to the more ancient rocks of this region, we have seen(>$ 140) that Foster and Whitney recog- niz(Hl besides the Azoic schists, called Ijy them Metamoi'- phic, a great group of Igneous rocks, ol" different ages, in which were incbuled granites, viirlous gi-eenstones and hornblende rocks, and the crysialHne iron-ores. In this they were not singulai', but in accordance with the generally received views of the time. Henry D. Rogei's regarded the greenstones, epidotic rocks and serpentines of the Atlantic belt as igneous, and extended tliis view to the magnetic iron-oi'es, and even to the cpuirtz veins of that regicm (jj 19, BO, H2, B7, ;]9). Fnnu(ms, in likc^ manner, included the granite, hypersthene-i-ock, ser[)entine, limestones, and raag- netic and specular oxyds of iron of northern New York, among the unstratilied rocks of igneous origin, (§ 8i)-87) and Logan held the same view with regard to the ILironian KIMBALL OX LAUHKXTIAX AND IirKOMAX. E. 221 gTt^enstones, (^ 141) ;iltli()uu,'li Rivot denied this, and nssorted that they were altered sediments, a view wliich he extended to the traps of the Upper Copper-bearing series (§ loT). § 428. The arguments of Rivr>t, from the relations be- tween the greenstones of the okler series and their associ- ated schistose rocks, (§ 152) were valid, and he eri'ctl only in considering them the sti-atigraphical ecpiivalents of the gianidar traps and amygdaloids of the newer series. The studies of the writer in the years following, coniirming such a conclusion, the indigenous character of these and sim- ilar greenstcmes, and other feldsp .riu(! rocks, was maintained by him in various publicati(ms, from 18r)8 (Chem. and Geol. Essays, pages 4, '•]',]). Tliis view is set fortli at length in Chapters XIX and XX of the Geology of Canada, and further, in Conti-ibuticms to Lithology (Amer. Jour. Sci. II, xxxviii, 253). The writer had already ])i-oposed to desig- nate by the term ind/r/enous, such crystalline rocks as have been formed ht .S'/M, in contradistinction to tliose Avhich have been intruded into tlieir i)resent places, and wliich Avere called e.volic The name of cndof/ciioKs rocks was prox)osed for a third class of nuneral masses, namely, the c( )nci'eti()nary vein-stones. § 429. In 180.-) appeared an impoitant paper on the Iron Ores of Marcxuette, by Dr. J. P. Kimball (Amei-. Jour. Sci. II, xxxix, 21)1) in which were set forth his studies in the Azoic system of Whitney, as s<'en in northern Michigan. He showed that the (>xtensive belts oi' ran<^'es, called i)lutonic ii'ranites ])v Foster and Whitnev. and supiKtsed bv them to lie more recent than the Azoic schists, w<'re really indig- enous gneissic rocks, behmging to an older series, which lie pronounced Laurentlan. As ivgards the overlying schists, he ccmlirmed the judgment of Murray that they be- Iciig to the Iluronian series, tlu^ greenstones and iron-ores of which were also declared to b(Miot exotic butiinligenous. Kimball, at the same time, jHiinted out the erioi- of IJivot in uniting the Upper Copper-bearing series with tlie Iluronian. lie also nniognized the existence, in the region, of eruptive granites and greenstones, as Murray had m i 222 E. SPECIAL REPORT. T. STERRY HUNT, 1875. already done in Canada, but declared that, though abundant in the Laurentian, they were very rare in the Huronian. § 430. In 1809, Dr. Hermann Credner published his studies of these same rocks in northern Michigan. He followed Kimball in admitting an older series of granitic gneiss — the Laurentian — which was unconformably overlaid by the Huronian rocks. These were described with muc' litho- logical detail, and with many sections, as a series ol ^uartz- ites, limestones and red iron-ores, with argillaceous, clilor- itic and talcose slates, the latter two associated with diorites, which were declared to be not eruptive masses, but regularly interstratilied members of the series. (Zeitschrift d. Deut- schen geol. Gesellschaf t, 1869). Credner estimated the total thickness of the series at about 20,000 feet, which agreed nearly with Murray's previous estimate of 18,000 feet, (Geol. of Canada, page 57). § 431. In 1869, Major T. B. Brooks, who had been asso- ciated with Prof. R. Pumpelly (with Credner as assist- ant, ) in geological explorations in the northern peninsula of Michig[in, commenced for the State, a systematic survey of that region. The results of their labors are set forth in the two octavo volumes of the Geological Survey of Michi- gan, published, wdth an atlas of maps, in 1873, in which the iron-bearing or Huronian rocks are described l)y Major Brooks, and the Upper Copper-bearing series by Prof. Pum- pelly. In 1869 and 1870 large collections of rocks from the older series from Michigan, were by Prof. Winchell, then the directt)r of the geological survey of that State, and by Major Brooks, placed in the writer's hands for examination, some of the results and conclusions of which are given in the following extracts from a letter addressed by him to Major Brooks, and dated Montreal, Feb. 22, 1871 : § 432. "I find you are waiting for my conclusions, some of which are very interesting and important. You remark about the mica-schists, as being supposed by mo wanting in the Huronian of Canada, and you send me specimens, Nos. 1215, bU54, bll53. I have for some time past recognized a Mica-schist series, which T suppose to overlie the Huron- ian, in fact the White Mountain series. * * I was MOXTALBAN KOCKS OF MICHIGAN. E. 223 therefore deliglited to find in the specimens just naiii<>d, well characterized White Mountain mica-schists, holding garnets, and well-defined crystals of staurolite, while the peculiar knotted mica-schist is not less characteristic. These rocks are abundantly spread to the north of Lake Superior, as last year s collections [of the Canada Survey] show me, and though I have been not able to fix their re- lations to the Iluronian diorites, talcose schists, iron-ores, etc., I conclude from the facts seen near Portland, in Maine, and those described by Rogers, in Pennsylvania, that they are overlying rocks, and, in some cases at least, v.nconform- ably so. You say that they are the youngest rocks in the region belonging to the Iluronian. I susj^ect that they be- long to a younger series." "I distinguish three crystalline gneissic series : I. Laurentian, (not to speak, for the present, of the Labradorian) ; II. Iluronian ; III. Terranovan [Mon- talban], these being respectively, in the United States, the rocks of the Adirondacks, the Green Mountains, and the White Mountains. I hope you will be able to decide whether there is any want of conformity between II and III. I should mention that in Hastings county, Ontario, the three series are all represented, and there is apparently a strati- graphical break between each." "I have thus, I think, ■* * touched npon the principal points of interest in your collections, of which the two chief facts, are the close resemblance, and I believe identity, of the great iron-bearing dioritic, talcose series with the Green Mountain series, IT, and the equally close resemblance of the rocks 1215 and lir)l-lin4, with the AVhite Mountain series III, which I conceive to belong to a higher hoii/on."' §4^3. "The collections sent last '■'" ^ * from Smith's ^fountain and vicinity, are also members of what I regard as series III, and quite unlike the Iluronian type, II." [Here follow(Hl details of thirty-nine specimens.] "Many of these rocks are very quartzose. Feldspar is occasionally devel- oped, giving a gneiss A\hicli is seen in * * and * * in which the white cleavable orthoclase is developed so as to form a porphyritic gneiss." § 434. "A word about felsites. I have a large si)ecim('U I 4 I ■ I il ST '! i''- 224 E. SPKf'lAL REPORT. T. STP^RRY IICXT, 1875. of conulomemte, with native copper, from tlie All)!iin^ & Boston Miniiiii; Co.'s i)roperty, brought me by Mr. Macfar- lane, who hus brielly desci'ibed it in the CTeoh)gical Report of Canada for 18G:}-(J(5, pa,i.?e 156. Tlie poi-phyry boulders and pebbles of which he there speaks, are line examples of th(3 felsite of Avdiich 1 wrote you, better named eurite or peti'osilex, and i)assiui;- into quartziferous porphyry. ■* * What is the source of the boulders? I suspect it will be found in the lower part of the Uuronian system, for it has the typical character of tlie Uuronian eurites, as seen along the east coast of N(?w England, etc., from Rhode Island to Newfonudland. and also to the north of Lake Ontario. Do you know any such rock i/i .svYii, and have you jierhaps deeuKHl it erui)tiver' § 435. The above conclusions as to this overlying gneiss and mica-schist series, was soon after made known l)y the writer, in his address in August. 1871, (§ 347), where it was said that the schists both of the Green Mountain and the White Mountain seiies '*ai'e represented in Michigan, as ap- pears by tin? n^'ent collections ol' ^lajor Brooks '-^ * kindly placed in my hands for examination. He infoi-ms me that thes(? latter schists are the highest of the crystal- line strata in the northern peninsida." (Chem. and Geol. Essays, page 274). § 436. Tlie above collections were from the Marquette re- gion, and the schists referred to the White oMountain series were designated by Brooks in his report, in 1873, as division No. XIX, described as "a formation of great extent and in- terest," "tlie youngest member of the series" of Uuronian rocks, and "one of the thickest" in the u])per jxminsula of Michigan. It is often v(>ry silicious and micaceous, and con- tains besides black horiiblennting a Laurentian as])ect, thcnigh "conformably oveilying rocks unmistakably Uuron- ian." BROOKS ON TUE MONTALBAN OF MICHIGAN. E. 225 § 437. In his subsequent examinations of the rocks of northern Wisconsin, to the soutli and west of the ^lenome- nee river, Brooks found in the Penokie region a great area of similar gray gneisses, often granitoid, associated, as be- fore, with hornblendic and mica-schists. These latter he regards as the equivalents of division XIX of the Miiiquette region, and at the same time suggests that some of the granitic rocks of the latter area may be identical with what he calls the Penokie granitoid formation. These later observations and comparisons, were set forth by Brooks in 1875, in a paper on The Youngest Iluronian Rocks, etc. (Amer. Jour. Sci. III. xi, 20G) under which head he includes the three areas of granitoid gneisses, with their associated hornblendic and micaceous schists. From their similar lithological characters, the entire absence from them of ^he iron-ores, which abound in what he calls the middle and lower portions of the Iluronian, and from their geognostical relations alike to these and to the unconformably overlying UiDper Copper-bearing series, Brooks concludes that the granitoid formation must be regarded as the youngest mem- ber of the Huronian series. § 438. It will l)e noticed that the immediate associate of this granitoid formation in each of the three districts is the peculiar micaceous and hornblendic schists, XIX, and it was these schists, and the granitoid gneisses, from the Mar- quette region, which the \vi'iter, so long ago as 1871, re- ferred to the White Mountain or Montalban series, then, as now, placed by him above the Huronian — a testimony to the value of lithological characters in geology. In his paper already quoted, Brooks remarks on this point: "I would anticipate the objections which many will make to attaching much weight to lithological evidences in deter- mining the age of formations one hundred miles apart, by repeating that the staurolitic mica-schist formation ( XIX ) maintains its mineralogical characters for over one lialf that distance." For further notices of these gi'anitoid gneisses of the Montalban series, see Chem. and Geol. Essays, i^ige 188, 244. These rocks have certain lithological resemblances to the gneisses of the Laurentian, but their inherent tliffer- [E. 15. J 226 E. SPECIAL REPOUT. T. STEHRY HUNT, 1875. ences, not less than tlie character of the associated schists, suffice to distinguish them. § 439. Tlie greenstones of the Huronian of Lake Superior, have been generally described as diorites, and the correct- ness of this designation is confirmed by the microscopic studies of Julien, and of Wright, who find them to be es- sentially composed of a triclinic feldspar and amphibole, (hornblende) frequently with chlorite. According to the former, some of them " may possibly contain pyroxene in place of amphibole." (Geol. of Micliigan, 1873, II, 43). § 440. In the writer's account of the similar rocks from the Green Mountain range in Canada they were desciibed as rocks composetl in part of triclinic feldspars. "Through an admixture of hornblende, these feldsjiar-rocks pass into diorite, in different varieties of which the one or the other mineral jiredominates. * * * These compound rocks are often so finely granular as at first sight to appear homogenecjus ; at other times they are rather coarse-grained, and sometimes porphyritic from the presence of large crys- tals of feldspar. * * The imbedded hornblende- crystals are occasionally of considerable size, and darlv- green in color. In some places, the hornblende is replaced by pyroxene or diallage." After describing the relations between the steatites, dial- lage-rocks and serpentines, which often accompany these feldspathic rocks, it was said: "Both the serpentines and the diorites sometimes become schistose, and the latter seem to graduate into chloritic slates nnd epidosites, on the one hand, and into hornblende slates on the other, so that it is difficult to resist the conclusion that the whole series of rocks just named, from diorites, diallages, and seri^entines, to talcs, chlorites and epidosites, have been formed under similar conditions." (Geok)gy of Canada, pages 602, 012). See further, Amer. Jour. Sci. II, xxxvii. 2G6. §441. A belt of Ilaronian rocks is found in southern Connecticut, to the west of New Haven. These were de- scribed by the late Prof. Silliman, more than half a century since, as "primitive greenstones," and later, by Percival, as a "chloritic formation." In 1870, J. D. Dana published HURONIAN GREEX8TONKS. E. 227 some notes on these rooks, describing the association of tlie greenstones with chhjritic schists, and with serpentines, and adopting the previously announced conchision of the writer, tliat " their common metamorphic origin cannot be questioned." Tliese rodvs were at tliat time submitted to an examination by Mr. George W. Hawes, who found two of tlu?m to be identical in chemical composition, respectively, with an exotic dolorite and an exotic diabase, which, a few mik^s dis- tant, in the vicinity of New Haven, break through the mesozoic sandstones. These exotic masses moreover closely resemble in aspect the indigenous rocks in question, which were accordingly described as aggregates of labradorite and pyroxene, (with some titanic iron) with the addition, in one variety, of a portion of chlorite (Amer. Jour. Sci. Ill, xi, 119 and 122). § 442.. Dana, on account of this apparent identity in lithological characters, pi-oposed to call these indigenous or metamorp hie greenstones, metadolerite and metadiabase. Such a nomenclature is however based on a misconception of the province of lithology, which is distinct from that of geognosy. In the language of the author, in 18G4, the same mineralogical aggregate "may occur both as an in- digenous and an exotic rock, and different portions of the same mass may be seen, by different observers, under such unlike conditions that one may regard it as indigenous, and the other with equal reason, set it down as intrusive." "To the litliologist, who examines rocks without reference to their geological reflations, the question of the exotic or indigenous character of a given rock is, in most cases, one altogether foreign, and one which can frequently be de- cided only by the geologist in the field.'' (Amer. Jour. Sci., II, xxxvii 2.")4). These remarks remain essentially true to- day, especially for many granitic and euritic or petrosilici- ous masses, although the use of th(» microscope now enables one, in many cases, to distinguish between the indigenous rock and its exotic representative, as in the case of the di- orites belonging to the two classes. § 443. It should be said that Mr. Hawes, by microscopic m 228 E. RPECIAL REPOIIT. T. STEllIlY HUNT, 1875. examinations, has since found tliat the indigenous green- stones noticed by Dana, are really diorites, in one case con- taining some chlorite. (Ibid, III, xv., 210.) The further extended studies (as yet unx^ublished) by Mr. Ilawes, of the Iluronian greenstones of New Hampshire have yielded sim- ilar results, and show that these rocks, also, are essentially diori(i(! in character, consisting chielly of an admixture of a plagioclase feldspar with hornblende, rarely containing grains of pyroxene, and often becoming chloritic, as long since described by the writer. From the similarity in chemical comj^osition, and the intimate mineralogical rela- tions between hornblende and pyroxene, it seems highly probable, that in accordance with the theory of exotic rocks maintained by the writer, (Chem. and Geol. Essays, 4, 9, 44), the exotic dolerites and diabases of the New Haven mesozoic are but displaced and modilied greenstones of the underlying Iluronian series. § 444. As regards the lithology of the Iluronian of north- ern Michigan, it may be remarked that although Julien found no well-defined serpentines, the writer examined some years since, specimens of both massive and fibrous serpentine, believed to be from the falls of the Sturgeon river, received from Dr. Rominger of the Michigan geologi- cal survey, which had the characters of the typical ser- pentines of the Iluronian of the Atlantic belt. Allusion should here be made to the serpentine of Presqu'isle, ana- lyzed by Whitney. (Geol. of Lake Superior, II, 92). The writer has found some of the serpentine rocks of this re- gion to be chromiferous. It is of interest to note the occurrence of large quanti- ties of a carbonaceous argillite, noticed by Brooks in sev- eral localities in the Huronian of Lake Superior, which has a black streak, burns white before the blow-pipe, and yields over twenty per cent, of carbon. (Geology of Michigan, I, part 1, 116). § 445. In the volume just quoted, the Upper Copper-bear- ing series was described as consisting of interbedded sand- stones, conglomerates, melaphyres and amygdaloids, dip- ping northward at an angle of fifty degrees or more, and over- i 1 PEI'UOSILEX UOCKS OF LAKE SUPEUIOK. E. 229 laid nnconformably by tlie nearly horizontal St. Mary's sand- stonos, in whicli Mr. Alex. Agassiz found, near Ilongliton, abundant pebbles of melaplu-re and conglomerate, from the underlviug series. No dirtn^t estimate of the vohime of these latter rocks was attempted, though it was said ''they have a thickness measured by miles, a tliickness which they exhibit wherever they are known, at points hundreds of miles apart on the north and south shore" of Lake Superior. As regards the age of this Upper Copper-bearing series, it was, at tliis time, by M(^ssrs. Brooks and Pumpelly, declnred to have been " formed before the tilting of the Iluronian beds, upon which it rests conformably," and to be probablj'' more closely related in age to those, than to the overlying paleozoic sandstones. (Ibid. I, part 2, pages 1-G). § 440. The reader is now prepared to understand the significance of the question raised by the writer in 1871, as to the existence of the felsite or petrosilex-porphyries, in place, in the Lake Superior region ; since tliese rocks, which had then been found by him to belong to the Iluronian series, (§ 363-372), occur in pebbles in the conglomerates of the Upper Copper-bearing series, (§ 434). Besides the locality already mentioned, the great cupriferous bed of the Calumet and Hecla mine is a remarkable example of a rock made up almost wholly of the ruins of these joeculiar petro- silexes. In 1872, as already described, (§ 372), he found these rocks, in siM^ on the north shore of Lake Superior, and was moreover led to suspect that both the banded jaspery quartzose porpliyry of the P(U'cux)ine Mountains, de- scribed by Foster and Wliitney as of igneous origin, (§ 151), and the similar rocks, said to occur at Mount Houghton in the southern range of Keweenaw Point, (§ 150); regarded by the same observers as an altered sandstone of the Upper Copper-bearing series, to which they referred tliis soutliern range, known as the Bohemian Mountains. § 447. The lithological characters of this southern belt, as alreadv described, are however verv like those of the Huron- ian, and widely different from those of the more nortlun-n belts, (§ 149) which are the typical Upper Copper-bearing rocks. This Avas noticed hy Dr. Charles T. Jackson, who 230 E. SPECIAL KEPOllT. T. STKKUY HUNT, 1875. jft^m r remarked that the labmdoritic fjreenstone of tlie south- ern portion, near Lake Labelle, diirers from tliat of tlie nortliern ranges, in being a crystalline rock. He adds witli regard to it : "If the rock were not connected with the more hornblcndic traps, and in the same line of diiecti(m, burst- ing through the same kind of sandstoii" strata, I shouhl feel disposed to regard it as of more ancient origin. Indeed, I am far from being satisfied that it is not more .incient, for the limited exposure of the rocks does not allow any geologist to be too conlident as to its age." (Report to 31st Congress, 1849, Exec. Doc. No. I, i)art iii, page 473). Mr. Ernest Gaujot, whose skill and long experience as a geological observer and a mining engineer, in this region, give much weight to his opinion, informs the writer that he has always believed the Bohemian Mountain range to belong to an older series than the copper-bearing rocks to the north of it. § 448. The reader who remembers that the Upper Copper- bearing series had already, in 1803, been declared by Logan to rest unconformubly upon the Iluronian, (§ 424) along the north shore of Lake Superior, miglit dfem this an answer to the views of Brooks and Pumpelly, who, in 1873, still supposed the two conformable, and nearly related in age. As will be shown farther on, lunvever, the writer, from his studies on the north shore, in 1872, was led to conclude that the rocks there overlying the Huronian, of which they con- tain fragments, are not, as was supposed by Logan and by Murray, a lower division of the Upper Copper-bearing series, but belong to a distinct formation, of indetermined age. He, however, found that the conglomerites of the tyi)ical Ujiper Copper-bearing series at Mamainse include, as already described (§ 150), rounded masses of tl' stones and chloritic schists of the Iluronian, :is we' characteristic gneisses and mica-schists of aii thus showing a stratigraphical break betwei liese stai line schists and the Upper Copper-bearing series ; ; iid con- firming the conclusion already reached from the oc> urrence of petrosilexes, believed to be Iluronian, in the conglomerates of the same horizon, in the Keweenaw peninsula. THK KKWEEXIAN SERIES. E. 231 § 449. The great serios of highly inclined Hnndstones and conglonjerates which, with intcrstrafitied trappcan masses, constitute the cui)i'irei(nis rorination of this region, and are clearly distinct both from the overlying sandstones and the underlying Iluroi'.ian sciusts, required a distin- guishing name. Hence, the writer, in his atldress on the Geognostical History of the Metals, before the American Institute of Mining Engineers, in February, 187:5, designated it tile Keweenaw gronp, and snggested that its included native copper had probably been derived from the oxy- dized and dissolved coj)per-sulphurets of the Huronian, (Trans, etc., I. 330, 341). In March 187."), Major Brooks, who had apparently overlooked the above announcemeut, but had himself, in the meantime, arrived at the conclusion that there exists a stiiitigraithical break, and a niarkfjd distinc- tion, between the Huronian schists and the Upper-Copper- bearing group, declared that the latter constitute "a distinct and independent series, marking a definite geological pe- riod," and proposed for its designation the adjective Ke- w^eenawian. (Amer. Jour. Sci. III. xi, 2I:en of as the St. Mary's sai.dstone. This was, in 18G3, 1'egarded by Logan as probably of the age of the St. Peter's or Chazy sandsfone of the Mississippi valley, (§ 10.")) and colored as such in the geological maps of 18G4 and 18(50 (§44). § 454. We have seen that Hall long since observed, in some beds between these sandstones and the overlying mass of Trenton limestone, strata containing organic remains of the Chazy formation. Dr. Rominger has since found, through- out the northern peninsula of Michigan, at this horizon, a series of beds, which, from their oi'gani(! remains, lie declares to reijresent both the Chazy, and the Calciferous formation, 234 E. SPECIAL REPORT. T. STERRY HUNT, 1875. of the New York series, leaving, according to him, no alter- native but to regard the underlying sandstones as the equiv- alent of the Potsdam." (Geol. of Michigan, 1873, Vol. I, pages 71, 80). These intermediate beds are partly calcareous or dol- omi'ic, and partly silicious, consisting of "small perfect quartz crystals, with glistening facets, and sharp, unworn angles." Mixed with these, ai'e numerous oolitic silicious globules, and, in some cases, masses of banded chalcedony, the whole recalling the observations made regarding the silicious beds of the Potsdam, in other localities (§ 2G9). § 455. These intermediate beds have a variable thickness, and in one case measure nearly one hundred feet. The thickness of the underlying sandstones, to the east of the co]3per- region, where they rest upon the older crystalline rocks, does not exceed tliree hundred feet, but to the west- ward, it is not easy to fix the limit between them and the older sandstones which form the upper portion of the Ke- weenian series, and are designated by Mr. Sweet as the Bad River sandstone. The upper portion of the Potsdam sand- stone, in this region is, according to Rominger, light-colored and friable, the lower is dark-red or variegated, and, as shown by Mr. Sweet' s analyses, contains a large proportion of clay and iron-oxyd, from the decay of the underlying Keweenian strata (Mem. Wis(;onsin Acad. 1876, page 60). ^ 45G. The identity between the crystalline schists of Lake Superior (including those of northern Michigan and Wis- consin,) and those of the Atlantic belt, pointed out by the write', in 1870 and 1871, is admitted by Mr. Francis Bradley, who, however, still holds, as we have seen, (§ 404) to the notion of the i)aleozoic age of the latter. In an exi)lanation of his geological map of the eastern half of the United States, published in 1 870, Mj'. Bradley writes : ' ' The typical Iluron- ian of Canada, according to description, occupies the posi- tion, and presents the lithological characiters which we should naturally expect for the metaniorphic portion of the adjoining Lowev Silurian [Cambrian], corresi>on(ling pre- cisely, in both aspe. ..s, with extensive beds of that age in the Appalachians. I have accordingly colored them Lower IRVING OX THE KOCKS OF WISCONSIN. E. 235 Silurian." "Considerable portions of tlie so-called Ar- clifcan area, in Wisconsin and Michigan, have been shown by Brooks, Punipelly and others, to be the equivalent of the Canada lluronian, for which reason they might with propriety be referred to the tiilurian, but the data, as yet published, seemed so incomplete that the writer has preferred to leave them uncolored." Bradley further remarks, that after reaching the above conclusion with regard to the pale- ozoic age of the typical lluronian: "I learned through Mr. Selwyn, that Sir William Logan held the same view, for some time before his death'' (Amer. Jour. Science III. xii, 287). To this assertion, Mr. Selwyn replies in the same volume (page 4G1), as follows: ''I am not aware that I ever men- tioned Sir William Logan to Mr. Bradley, in the matter, and certainly, if Sir William held the views attributed to him, he never informed me of the fact." Mr. Selwvn further adds, with regard to the lluronian rocks : '' AV(^ have not, so far as I know at xjresent, any evidence which could warrant us in classing them with the Silurian." To the above decla- ration, the present writer must add his owti testimony to the effect, that Sir William Logan, up to the last year of his life, admitted no such view as that attributed to liim by Mr. Bradley. § 4r)7. The above statements of Mr. Bradley called forth, in 1S77, a note from Prof. Irving (Ibid. Ill, xiii, 308), who sums uj) as follows, "the facts i)roven, thus far, as to the older rock-series of Wisconsin." These are, iirst, the exist- ence of an older gneissic and granitic series, the Laurontian -, second, the unconformable superposition upon this of a second crystalline series, the lluronian, (in which is in- cluded the Penokie giKMssic foriuatiou already mentioned) ; third, the superposition upon the lluronian, iu probabh' unconformity, of the great Keweenian series, with a thick- ness of several miles ; and fourth, the existence of a seiii's of horizontal sandstones, resting unconformably upon the Keweenian, and liolding the organic forms of the Potsdam sandstone. Pr(»f. Irvinir adds: "Inoi-der to incliid' the Wisconsin 23G E. SPECIAL REPORT. T. STERRY HUNT, 1875. crystalline rocks witliiii the Silurian, Mr. Bradley would have to stretch that term so as to cover three entirely distinct terranes, each overlying its predecessor unconformably, and many thousand feet in thickness ; the highest of the three, in its turn, overlaid unconformably by horizontal sand- stones nith Primordial [Cambrian] fossils. As to any ot the Wisconsin or Michigan rocks being altered equivalents of the Primordial, and newer strata, of the eastern States, such a hypothesis is certainly untenable for a moment." While conceding that such things may, as Bradley supposed, oc- cur in the Appalachians, (a region with which Prof. Irving is unfamiliar) he says, "there has certainly been no period of metnmorphism in the region of the northwestern States, since the beginning of the Primordial;" — a proposition which is equally true, in the writer's opinion, for the At- lantic belt. § 458. The Keweenian series has been shown to overlie unconformably the Iluronian and Montalban schists, and to be, in turn, overlaid in like manner by the Lower Cam- brian sandstones, thus occupying the same geological in- terval as the Lower Taconic or true Taconian series. With this, however, it has but very remote lithological resem- I blances, and, so far as known, nothing similar to the Ke- ! weenian series is found at this horizon, either on this con- ! tinent or elsewhere. If, however, as seems proba])le in the present state of our knowledge, the greater j)ii^i't of this series is to be regai-ded, in opposition to the opinion of Rivot(§ 153) — as of vokanic origin, its lithological peculi- arities are, in the nature of things, local, and have no chronological signihcance. We may recall, in this connec- tion, the resemblances already noticed between the Ke- weenian series and the beds of amygdaloid and cupriferous conglomerate, apparently of the age of certain graptolitic shales, in the Upper Taconic i-ocks, in the province of Que- bec (§ 185) and al. • the similar rocks of mesozoic age, in other regions. Charles T. Jackson, in 1840, argued from the litliological characters of the Keweenian series, that it was of the age of the New Red sandstone of Nova Scotia, Connecticut, Massachusetts, and New Jersey, and the same THE KEWEEXIAN SERIES. E. 237 view has been sustained by- Ma r-ou, and later, by Tliomas Macfarlane and by Robert Bell. The valuable geological and lithological observations of Macfarlane, in this region, are set forth in the Canadian Naturalist, in 1SG8, (new series, vol. III.) where, on page 253, he has given his reasons for regarding the Keweenian rocks as of the age of the lloth- liegende or Permian of Germany, Avhich they closely re- semble lithologically. § 459. The evidence since obtained from superposition, has however established their much greater antiquity, and con- firms the opinion, that the comjjosition of exotic rocks is in no way connected with the date of their extravasation. The conditions under which they have been ejected, whether as sub-aerial, sub-aqueous, or subterranean eruptions, and the consequently differing conditions of consolidatic i, must, hoAvever, necessarily modify greatly their minernlogical characters. It should moreover be considered, in comi)ar- ing older with newer exotic rocks, that the deeply-seated portions c:'' an erupted mass, which became solid under a vast pressure, and are now, in the case of older rocks, ex- posed by great subsequent erosion, must differ considerably in structure from the superficial and more-rapidly cooled portions of the same mass. Of such nature, for example, is the difference between granites and quartziferous trachytes. § 4G0. There are certain markings in the Keweenian rocks which are probably of organic origin. Logan, in 1847, de- scribed the occurrence in some of the earthy, or so-called tufaceous beds of the series, of numerous slender vertical tubes, filled with calcite, having a. diameter of about a quarter of an inch, and a length, in some cases, of from eight to twelve inches. Two or more of these tubes were often found to coalesce, in ascending, (Geol. of Canada, page 71) and they were supposed by Logan to have been formed by currents of gas rising through a pasty mass. From the ob- servations of the writer in 1872, on Michii)icoten Island, where similar markings were found in an argillaceous stra- tum, he was led to compare them with some forms of so- called ScoliiJius, and to regard them as due to the burrow- These were accompanied by large niiml)ers ing of annelids m 2138 E. SPECIAL IlEPOllT. T. STEUIIY HUNT, 1875. of two cuiious forms, the one club-shaped, and the other hemispherical, or dy 1- \ IIUROiNIAX AND LAUKKXTIAN OF THE ALPS. E. 245 ^ sylvania, and has lar»'ly been resuscitated for them, in New- v^ foiiudlaud, (^ :}77-379). Nicholson, moreover, a few yearn . >\ v since, applied a like view to the Ilnronian of Lake Superior, c^v / • , and recently George }>[. Dawson has expressed the opinion \^ / ri'\ that rocks litholoirically similar to these, in liritish Colum-H^s'^y^'f*' ^ bia, are of volcani<' oiii;in, and niesozoic in age. ^474. The greenstone gronp of the Alps has, like tin? similar rocks in North America, been, from its apparent stratigraphlcal relations in dillVivnt localities, assigned to various ages, in paleozoic, mesozoic, and cenozoic time. The late researches in Alpine geology, of Favre, Gastaldi, and others, have howv'ver led to a different c(mclnsion. According to the latter, the rocks of the greenstone groujj are not eruptive, but indigenous, and constitute a dis- tinct stratilled series, of great thickness, of beds and len- ticular masses, in which the serpentines occupy a position near the base. These vai'ious rocks, he declares, belong to a constant and well-defined horizon, which is pre-paleo- zoic, and never make theii- appeanince in other formations. This group has all the characters of the Ilnronian or Green- Mountain series, to which it has lieen refei-red by (iastaldi, and rests, probably unconformably, upon a great series of gneissic rocks, often porijhyroid and granitoid, which in- clude quartzites, graphite, and crystalline limestones, and are supposed by him to represent the Laun^ntian, of which they have the chai-acteristics. §47,"). The Iluronian in northern Italy is followed by a great series of quartzites, with calcareous schists, mica- ceous limestones, and dolomites, including gypsums near the summit. These rocks, like the pieiri verdi, have been, in turn, referred to various horizons from the Cretaceous to Lower Carboniferous, but a(;cording to Gastaldi, are of greater and uncertain antiquity. Their lithological char- acters, and their position, recall the Taconian of eastern North America. The three groups of crystalline strata above mentioned, are said by Gastaldi to constitute the basal rocks of Alps and the Appenines, and, overlaid in part by newer strata, may be followed fi-om Mont Blanc to the Dan- ube, the Adriatic, the Mediterranean, and the plains of 246 E. SPECIAL KEPOUT. T. STERRY HUNT, 1875. Fiunce. Gneisses and mica-schists, similar to those oi" the Montalban series, are also found in many parts of rhe Alps. The '•ead'>r may consult on this subject, two remarkable memoirs by Gastaldi, entitled, Sludli Oeologice sulle Alpi Occkic'/dall, and the same, parte scconda ; Firenzo, 1871 and 1874, in quarto, with numerous maps and sections ; also a letter by this geologist, entitled Spaccata Geolofftee liimjo le ValU Super iori del Po^ etc., {BoUetino del II. Comltato Oeologico, unno 187G, No. 3^). See further, Bui. Sac. Ghl. de France, 3me. s^rie. I, 208, and on The Geology of the Alps, Chem. and Geol. Essays, i)ages 329-348. The views of Favre and Gastaldi, though still opposed l)y some of the older school of geologists, are in harmony with all the facts of American geology, as set fortli in the preceding- pages. § 470. For a study of the euphotides and gabbros of the Alps, in vvhich the saussurite of the typical eupliotide is shown to be not feldsjiathic, but epidotic ; and for an ex- tended comparison of these rocks with the relatt.'d ones of the Iluroiiian of the Atlantic belt, see the author's memoir on Eupliotide and Saussurite, (Amer. Journal Science, II, xxvii., 330). For a similar study of serpentines, see his Contributions to the History of Ophiolltes, (Ibid, II, xxv, 217, and xxvi. 234). § 477. Some further account of the Montalban rocks, and their inchided granitic veinstones, may be found in th<' author's Chemical and Geological Essays, pages 194-200. The relations there pointed out, on pages 192 and 208, be- tween granitic, calcareous and metalliferous quart/ vein- stones, are well shov^ in Northbridge, near Worcester, Massac^husotts, where the gray fine-grained gneisses of the Montalban series, dipping to the soutlieast, are travf^rsed at right angles by several vertical ])arallel veins, which may be traced for considerable distances, and are ordiiiarilv but a few inciies in thickness. The veinstone in these is gener- ally a vitreous quartz, which in sr)me parts exhibits sel- vages, and in others, bands of white orthoclase, by an ad- mixture of whicli it elsewhere passes into a well characterized granitic vein. Tlie ipiartz veins, in phices, hold cubic crys- THICKNESS OF THE HURONIAN SERIES, E. 247 tals of pyrite, together with clialcopyrite and pyrrliotine, the latter in considerable masses, sometimes accompanied by crystals of greenish epidote, embedded in the quartz, and occasionally associated with red garnet. In one part, tliere is found enclosed in the wider part of a vein, between walls of vitreous quartz, a lenticular mass, three inches thick, of coarsely cleavable pink calcite, with imbedded grains of dark green amphibole, and, on one side, small crystals of olive-green epidote and red garnet ; the whole mass closely resembling some crystalline limestones from the Laurentlan. §478. In the account previously given of the Iluronian and Montalban rocks, as observed by Brooks to the south of Lake Superior, a notice of his latest publication on the subjei t, which appeared in September, 187G, (Amer. Jour. Sviience III, xii, jiage 194, ) was inadvertently omitted. In the tabular view there printed, the crystalline rocks, by Brooks called Iluronian, are divided into twenty groups. The granitoid gneisses, already referred to, (^ 4:}G-4;}8) as associated with the "great hornblendic and mica-schist series," XIX, previously regarded as forming the summit of the system, are now described as still newer than this, and are spoken of as "the youngest observed member, the granitic bed, XX, — only recently made out." It is these two divisions, XIX and XX, which the wi-iter has already referred to the Montalban, and which, according to Brooks, 0(Hui])y large areas both in the Menomenee and the Penokie regions. § 479. The observed thickness of the Iluronian in this region, exclusive of the overlying gneissic series, is esti- nuited by Brooks at not over GOOO feet for the Marquette district, and for those lying further west, on Black River, in Michigan, and where the Bad River crosses the Penoki«> I'ange, in Wisconsin. To the south of Marcpiette, in the J.Ienomenee district, it is said, the exposures may exceed 12,000 feet. We have however seen that in Wisconsin, according to Irving, the quartzites alone, of the Iluronian, in one section, measure over 4000 feet, and the petrosilex- porphyries. in another, not less than 3200 feet (§ 451). If 248 E. SPECIAL REPOET, T. STERRY HUNT, 1875. these rocks be comprehended, the estimates of 18,000 and 20,000 feet of aggregate thickness, made by Murray, and by Credner, (§ 430) do not seem excessive. Although the petrosilcxes were not noticed by the former, tlie presence; of them, lately detectetl by the writer in the collections made by Murray, twenty years since on Lake Huron, show that these rocks were, by that observer, probably included under the head of cherts and jasi)ers. The Iluronian series in New Hampshire, excluding the petrosilex-porphyries, called by him Lower Huronian, (§371) is, according to C. H. Hitchcock, a little over 12,000 feet in thickness. § 48(>. The thickness of the Montalban, as seen through- out the Atlantic belt, appears to be very greii t. Hitchcock, in his Geology of New ILimpshire, jiublished in 1877, (Vol. II, page 074) includes under this name a series described as gneisses and feldspathic mica-schists, librolite-schists, and "Concord granites," — the local designation of the fine- grained grayish micaceous gneisses of the Montalban. This series has, according to him, an aggregate thickness of 11,370 feet. Beneath this, he places 34,900 feet of rocks desig- nated as Laurentian, of which however the upper portion, called the Lake gneiss, and estimated at 18,000 feet, is in the writers opinion, probably, Montalban. Notwith- standing the a]iparent absence of the Huronian beneath the Montalban in I he sections given l)y Hitchcock, the writer has already set forth his reasons for believing the latter to be the younger series. It is probable that a portion of the crystalline scliists which, in certain sections, overlie, ac- cording to Hitchcock, the Huronian, may also belong to the Montalbjui terrane. § 481. As we have already seen, the hypothesis put for- ward by Matlier, n 1843, that the whole of the crystalline rocks of western New England are but altered paleozoic strata of th(^ Cliamplain division, (^81) has lately been re- vived by Prof. Bradley, who has extended it to the similar rocks of the Blue Bidge, and of the vicinity of Lake Su- perior (§404, 456). In a Handbook of Georgia, published by the Commissioner of Agriculture for tliat State, in THE BLUE RIDGE IN GEORGIA. E249 1876, and accompanied by a geological map, is a sketch of the geology of Georgia, which is understood to embody the opinions of Bradley with regard to the crystalline rocks of that State. It is therein declared that Fulton county exhibits both "the Cincinnati gneisses," and "the reddish and gray hydro- mica schists, with some outcrops of the steatite and itacol- undte, of Quebec age." In Habersham county, the rocks are referred to the same two divisicms ; those of the Blue Ridge jH'oper, like those of the Chattahoochee Ridge, being- said to consist of "hard horublendic gneiss of Cincinnati age," while the softer schists of (he intermediate valleys are supposed to belong to t' Quebec period, (loc. cit., pages 40, 49, 59.) § 482. These same views are set forth, with further detail, in the exi)lanations accompanying the catalogue of a col- lection of the rocks and minerals of Geoi-gia, sent to the Paris exhibition of 1878 ; the catalogue having been prepared by Dr. George Little, the State geologist. It is theicin said of the crystalline rocks of the State, that, altiiough without fossils, they "apx)arently are all stratigraphical ecpiivalents of the Lower Silurian : "in which however the only divisions recognized are the following, in ascending order : 1 . Acadian or Lower Potsdam ; 2. Upper Potsdam ; 3. Quebec grouj), and 4. Cincinnati group. The thicknesses there severally assigned to tliese are given vvitli a qu(My. The first, or Acadian, estimated at 13,000 feet, is said to consist of micaceous and livdro-micaceous schists, witli bands of gneiss, having but little hornbh:'nde. It also in- cludes rooiing-slates. The second, or Upper Potsdain, of 2,000 feet, is made up of heavy-l)edded gneisses, with little hornblende, as before, and with few schists. The thiid, or Quebec group. 12.000 feet thick, consists, in its lower ])ai't, chiefly of hydro-mica schists, with Ix^dsof honiblende-schist, gneiss, and quartzite, with much gai'Utit, cyaniteaiid rutile ; and in its upper i)art includes limestone and dolomites, with beds of chrysolite-rock or dunite, associated with serpentine and other niagnesian ndnerals, and with corundum. The fourth, or Cincinnati group, 15,000 feet thick, is chiefly 2oO E. SPECIAL REPORT. T. STERRY HUNT, 1875. gneiss, in great part hornblendic, with but few liydro-mica Rchists, "It probably includes the flexible sandstones of the npper part of the Itacolumite series of Lieber," the lower part of whic^h is said to be embraced in the Quebec group. All of these divisions are declared to be more or less auriferous, with the exception of the Acadian ; bat the rocks holding the chief part of the gold of the region are placed in the lower portion of the Quebec group. § 483. The vvuiter has very recently had the advantage of examininti:, in some detail, the crystalline rocks of the region in qnestion, in company with Br. Little. The roc^ks of the so- called Cincinnati group, whether seen in the vicinity of Atlanta, Fulton county, at Mount Airy, Habersham county, or at various p'^ints intermediate, along the line of the con- necting railway, are the characteristic hornblendic; gneisses and mica-schists of the Montalban. The same is true of the greater part of the rocks exposed in the se('tionfrom Mount Airy, by the base of INlount Yonah, to the Unaka Gap in the Blue liidge, in AVhite county ; nor was there met with in this section across the whole mountain-belt anything represent- ing the Iluronian, or so-called altered Quebec group; as seen in the Green-Mountain range in Canada. In the valley on the northwest of the Chattahoochee Ridge, near Clarksville, in Habersham county, there were found outcrops of unctuous slates, which resemble those of the Taconian, and mav be associated with the limestones, said by Prof. Bradley, to be quarried in the vicinity. The whole section, including the gold-bearing strata of the Nacoochee valley, bears a close resemblance to that already described across the same mountain-belt to the southeast of Roan Mountain, in North Carolina (§ 207.) Stcme Mountain, near Atlanta, ic a good example of the micaceoi s granitoid gneiss of the Montalban, so well known in New England ; — the Concord granite of Hitchcock. § 484. The Montalban rocks throughout this region are, with local exceptions, (as in the mountain just named,) more or less completely decayed, often to a depth of lifty feet. The liornblendic gneisses, though still retaining con ■ sidei-able coherence, have lost the greater part of their THE CAMBRIAN SERIES IN GEORGIA. E251 weight intlie process ; their specific gravity liaving been re- duced from 2.97-3.08 to 1.20, and, for some varieties, to less than 1.00. These decayed hornblendic rocks, by the action of the weather, yield a strong red soil. The de- cayed mica-schists, which still retain their micaceous character, liave there been called hydro-mica schists, though distinct from those of the Taconian, with which they have been confounded. § 485. The uncrystalline formations of Cambrian and Siluro-Cambrian age, as displayed in norchwestern Georgia, present, according to the catalogue just cited, the folio Aving characters. Above the Ococe slates and conglomerates, which are of great but uncertain thickness, is found the Potsdam or Chilhowee sandstone, estimated at 2,000 feet, followed by the Knox group of limestones, sandstones and shales, (regarded as the representatives of tlie < 'alciferous sandrock and the Quebec group,) witli an aggregate thick- ness of 4,400 feet. To these succeed thf Cliazy limestone, GOO feet ; the Trenton limestones and shales. 700; and the Cincinnati group, consisting of silicious limestojH^s and shales, with layers of red hematite, from 200 to 400 ; making in all about 8,000 feet of sedimentary strata from the base of the Potsdam. These, by the liypothesls of Prof. lUradley, become, in their extension a short distance to the south- eastward, iransformed into the 29,000 feet of crystalline rocks which he has referred to the Upper Potsdam, Quebec and Ciiicinn:»ti groups ; the intermediate divisions l)eing no longer distinguishalile. § 486. The arguments in favor of such a hypothesis, which have been urged by various writers on American geology since the times of II. J). Rogers and Mather, may be summed up under two heads: First, the ai)i)ai'ent stratigra])hi('al succession ; and second, thesu^iposed evi(hmces of ti'ansitioii from the uncrystalline to the ciystalline rormalioiis. The mode of reascming under the fii-st, as a])plie(l to the rocks of tlie Atlantic belt, may be faii'ly stated to be as fol- lows : Having assumed the possibility of such a transfor- mation in litliological characters, and liaving taken for granted that the wliole succession in question is a conform- 252 E. SPECIAL REPORT. T. STERRV HUNT, 1875. able one, without inversions or dislocations, a section is constructed from some formation in the paleozoic series, on the west side of the mountain-chain, and the crystalline rocks beneath which this formation ai)pears to pass, to the eastward, aresupy)Osed to represent the succeeding members of the paleozoic series in question. The radical faults in this reasoning are: First, that it overlooks the well-established fact that the i:)revailing structure in this mountain-chain is what may be described as a series of inverted folds, and of dislocations, as the re- sult of which (nt least in its western portions) the newer rocks dip, or seem to dip, eastward beneath the older ones ; and second, that it assumes the yjoint to be proved, namely: The possibility of the conversion of great masses of sand- stone, limestone, and shale, into feldspathic, hornblendic and ndcaceous strata. § 487. The fallacies of the method are strikingly shown in its contradictory results, as illustrated by the different paleozoic horizons to winch vai'ious theorists of this school have, in turn, assigned each terrane of the Atlantic belt. This has been abundantly shown in the i)receding pages, for the Iluronian and the Taconian. As regards to the Mont- alban, the characters of which are perfectly well-defined and jiersisteiit from New Brunswick to Alabama, we have seen that Messrs. Rogers, from a supposed parallelism with the paleozoic rocks of Pennsylvania, assigned the Montalban of the White Mountains to the lower half of the true Silu- rian, namely : the Oneida, M<'diiia and Clinton formations of the New York series. Logan subsequently referred the same crystalline terrane to the Devonian period, having successively placed the Iluronian in the Siluro-Candjrian, and in the Candirian : while Bi-adley now makes the Montalban rocks to embrace both of these latter, leaving no place in his scheme for the Iluronian. §488. As regards the secoiul argument, that from the imagined passage from crystalline to uncry stall ine rocks, we need only allude, in this place, to the existence of beds made up from the ruins of the former, which have been supposed to show the conversion of sedimentary into crystal- CHANGES FUOxM LAURENTIAN To CAMIUJIAN. E. ^^S line strata, instead of the reverse process. This point lias already been illustrated in § 184 and § 413. Distinct from such cases, are the statements ol' Mather, (§ 81) accordiiiu" to whom it is possible to trace, ou the east side of the river Hudson, a gradual passage from the rocks of the Champlaiu division, across those of the Taconic series, to the crystalline schists of New England. This supposed transition was however leased cm the false assumption that the Siluro-Cambrian and the Cambrian or Upi)er Taconic of that region, are one and the same series, and that their ap- parent lithological dilTcreuces are due to the commencement of a metam(U'phosis, which is still further seen in the marbles and schists of the Taconian, and reaches its highest i)<»int in the crystalline terranes further to the east. It will, how- ever, be evident from what has gone before, that these different types of strata are not, as was imagined l)y Mather, the result of subse(xuent and unlike changes which one and the same uncrvstalline paleozoic series has suffered in different geographical areas ; but that, on the contrary, they belong to successive periods in paleozoic ami eozoic time. The great divisions of the latter, as set foith in § 409, present, in ascending order, a progressive change in mineral characters, the nature of which has been shown in § 405, 406 ; thus constituting a veritable passage, in time, from the granitoid Ottawa gneiss at the base of the Laui-entian, through the internKxlia te Iluronian and Montal 1 )an divisions, to the less markedlv crystalline schists of the Taconian. The important question of the genesis of the crystalline rocks will be discussed in another place, but, in tlie mean time, an outline of the writer's views may be found in the preface to the second edition of his Chemical and Geological Essays, j)ages xxvii-xxxi. Second Geological Survey of PEiNnsylvania. REPORTS FOR 1874, 1875, 1876, 1877, AND 1878. The I'oUowiniif Reports ure issued for tlio State liy the Boiird of Cominia- niissioiicrs, at irarrishnru and tlie prices iiave been fixecl as foUows, in a(^ cordance witli tlie terms of die a(!t: PRICES OF REPORTS. A. 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