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 Reprinted from The Journal of Geology, Vol. II., No. i 
 January-February, 1894 
 
 THE DISTRIBUTION OF 
 
 Ancient Volcanic Rocks 
 
 ALONG THE EASTERN 
 BORDER OF 
 
 A^ORTH America 
 
 1 
 
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 \ 
 
 GEORGE HF WILLIAMS 
 
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 CHICAGO 
 D. C. HEATH & CO., Directors 
 
 01 
 
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I'l.ATK I. 
 
 [ 
 
 !.»»* 
 
 THE 
 ROBABLB 
 
 ES OF 
 
 NIC ROCKS 
 rH AMEBICA 
 
 ON WILLIAMS 
 
 I PROBABLE 
 
 Bntdirl i Co.. Engr>; Chi, 
 
 With the campltments at 
 
 George Huntindtdn Williams, 
 
 Johns Hopkins University, 
 
 UALTIMHRE, MIJ. 
 
 JOURNAL OF GEOLOGY 
 
 JANUARY-FEBRUARY, 1894. 
 
 THE DISTRIBUTION OF ANCIENT VOLCANIC ROCKS 
 
 ALONG THE EASTERN BORDER OF 
 
 NORTH AMERICA.' 
 
 CONTENTS. 
 
 Introduction. 
 
 Diversity of Opinion regarding Ancient Volcanic Rocks, 
 
 Great Britain. 
 
 Germany. 
 
 Belgium and France. 
 
 Scandinavia. 
 
 Russia. 
 
 America. 
 Criteria for the recognition of Ancient Volcanic Rocks. 
 Distribution of Volcanic Areas in Eastern North America. 
 
 Eastern Canada (Newfoundland, Cape Breton, Nova Scotia, Gasp^, New 
 Brunswick, Eastern Townships). 
 
 New England States (Maine, New Hampshire, Massachusetts). 
 
 Middle Atlantic States (New York, Pennsylvania, Maryland, Virginia). 
 
 Southern States (North Carolina, South Carolina, Georgia, Alabama). 
 General Conclusions. 
 
 The great crystalline belt of the Eastern United States and 
 Canada, in spite of all the attention it has received, is probably 
 still the least understood geological province of our continent. 
 Here, alniost more than anywhere else, personal adherence to 
 some preconceived theory of the origin and relationships of rocks 
 has biased observation and led to contradictory or unsatisfactory 
 
 • This paper was outlined at the International Geological Congress in Chicago, 
 August, 1893, »nd read in full before the Geological Society of America at its Boston 
 Meeting, December 28, 1893. 
 Vol. II., No. I. i 
 
THE JOURNAL OF GEOLOGY. 
 
 interpretations of the facts. Only within recent years has 
 detailed and independent work been undertaken in, widely sepa- 
 rated parts of this vast area, and as yet no sufficient data is at 
 hand for stru tural, or even for petrographical correlation 
 throughout the whole. 
 
 Complete geological maps, showing the structural relations 
 and chronological sequence of all the crystalline formations, are 
 undoubtedly what must be looked forward to as the ultimate aim 
 of work within this region, but the most sanguine will surely 
 admit that we are at present a long way from any such reality. 
 Meanwhile, in the absence of paleontological evidence, the study 
 of the rocks from the point of view of genesis and the establish- 
 ment of petrographic correlations will do much toward furnish- 
 ing the positive basis of knowledge upon which final solution of 
 complex structure must rest. 
 
 Some of the notions regarding petrographic sequence and 
 the origin of foliation, enforced by masters of geology high in 
 authority, have obscured rather than advanced the problems pre- 
 sented by the crystalline rocks in eastern North America. Not 
 only have we been taught that the mineralogical and structural 
 characters of these rocks are safe indices of their superposition 
 and relative age, but the interpretation of all parallel structures 
 as proofs of sedimentation has led to the conclusion that igneous 
 rocks are rare, if not altogether absent, in these oldest and gen- 
 erally foliated formations of the earth's crust. Now, however, 
 better conceptions are beginning to prevail. No longer do we 
 regard the petrographic character of a crystalline rock as any 
 criterion of its age, while modern methods have enabled us to 
 identify the abundant igneous rocks of ancient times in spite 
 of the misleading structures imparted to them by secondary 
 causes. 
 
 Object of this paper. — The present writer has had frequent 
 occasion to insist on the presence of such disguised igneous 
 masses in the oldest geological formations, and to dwell upon 
 the methods by which their origin may be established. In the 
 present paper it is his object to show that not only igneous, but 
 
 11 
 
THE D/STRinUT/OX OF ANCIENT VOLCANIC ROCK'S. 3 
 
 also volcanic' rocks arc widely distributed tiirough the crystalline 
 belt of eastern North America, and to direct attention to them as 
 offering a new and promising field for work in crystalline geol- 
 ogy. For tho accomplishment of this purpose it will be neces- 
 sary ''i) to consider the general attitude of geologists in differ- 
 ent countries toward ancient volcanic rocks; (2) to specify the 
 criteria c-vailable fpr their identification ; and (3) to summarize 
 our present knowledge of where such rocks certainly or probably 
 exist in the eastern crystalline belt. The material embraced 
 under the third of these heads has been obtained from personal 
 work in th'-' field, from a careful study of existing literature, and 
 from unpublished observations and hints furnished by friends.* 
 
 It is hoped that the bringing together of what is now known 
 of the distribution of ancient volcanic rocks in eastern North 
 America, with the addition of new areas and indication of locali- 
 ties where they may be looked for, will stimulate further work 
 in widely separated portions of this interesting field. These 
 rocks have, it is true, already been correctly described at a few 
 isolated points, but no attempt has before been made to connect 
 such areas or to show their probably widespread distribution. 
 The recent identification by the writer of a very extensive devel- 
 opment of pre-Cambrian lavas and volcanic tuffs and breccias in 
 the South Mountain of southern Pennsylvania and MarylandJ 
 
 » The term volcanic might, perhaps be applied with propriety to all rocks pro- 
 duced in or on a volcano, without regard to their structure or coarseness of grain. It 
 is, however, here employed only for effusive or surface igneous rocks, in contrast to 
 such as have so'!.;ified beneath the surface, either as the basal portions of volcanoes, 
 or as dykes, -,! - laccolites, or stocks (bathylites). 
 
 » The writer especially indebted for help to Professor Eugene Smith of Ala- 
 bama ; Professor W. S. Bayley, of Waterville, Me.; Professor J. A. Holmes, of North 
 Carolina ; Professor H. D. Campbell, of Lexington, Va.; Dr. A. C. R. Selwyn of 
 Ottawa ; Mr. L. V. Pirsson, of New Haven ; Professor S. L. Powell, of Newberry 
 South Carolina, and Mr. Arthur Keith, of Washington. The " Azoic System" of 
 Whitney and Wadsworth. and Professor Van Hise's Correlation Essay on the Algon- 
 kian have also proved of much service. 
 
 3 Am. Jour, of Science (3d sen). Vol. 44, p. 495, Dec. 1892. These rocks have 
 been thoroughly studied by Miss Florence Bascom, whose results may be expected soon 
 to appear in full and adequately illustrated form. See also this Journal, Vol. I No 8 
 Dec, 1893. ■ ' 
 
 \ 
 
 , I 
 
 w^??s^»^-f «-i wsf ?<! »i r^/!gj * ?*: wr l; -j r aMt ^' 
 

 4 THE JOURNAL OF GEOLOGY. 
 
 naturally suggested a comparison of these rocks with those of 
 similar character in the Boston basin and eastern Canada, as well 
 as a further search for other regions of the same kind. This 
 search has already proved successful in North Carolina and 
 Maine, while an examination of the older literature indicates 
 many other places where a recurrence of like conditions may be 
 confidently expected. 
 
 The proper interpretation and areal mapping of all the 
 demonstrably volcanic regions in the Appalachian crystallines 
 will not only afford much material of interest in the study of 
 petrography and dynamometamorphism, but will also contribute 
 to the differentiation and final understanding of the vast belt of 
 diverse crystalline rocks to which they belong. 
 
 DIVERSITY OF OPINION REGARDING ANCIENT VOLCANIC ROCKS. 
 
 There is notable in the different countries where geology 
 is cultivated a wide diversity of opinion regarding ancient vol- 
 canic rocks. In some regions such rocks have been entirely 
 overlooked or else misinterpreted ; in others they are recognized, 
 but are conceived as having been formed under circumstances so 
 different from those which now obtain that they are genetically 
 and inherently distinct from the products of modern volcanoes ; 
 in a few only are they considered as having been origin- 
 ally identical with recent effusive rocks, and as differing from 
 them only in alterations due to subsequent causes. This diver- 
 sity of opinion may be accounted for in part by the varying state 
 of preservation of ancient volcanic material in different parts of 
 the earth's surface or by the lack of experience of field geolo- 
 gists with the characteristic features of modern lavas. It is, 
 however, also due in a measure to the persistence of certain 
 ideas promulgated by early masters of the science in their 
 respective lands. 
 
 It was in Great Britain that the real nature of ancient volcanic 
 products received its earliest and fullest recognition. In spite 
 of the absence of active volcanoes from the islands, these rocks 
 have from the earliest days of geological inquiry been favorite 
 
THE DISTRIBUTION OF ANCIENT VOLCANIC ROCKS. 5 
 
 subjects of investigation. From the first, their essential identity 
 with modern volcanic products has been clearly recognized and 
 repeatedly insisted upon — something which wc may attribute to 
 the doctrines of Mutton and to the uniformitarian principles of 
 Lyell. Such geologists as Scrope, de la Beche, Sedgv/ick, 
 Murchison, Jukes, Lyell and Ramsay, speak continually of lava- 
 flows, tuffs, breccias and ash-beds in a way that implies no doubt 
 in their minds as to the existence of volcanoes like those now 
 active, in Paleozoic and pre-Paleozoic times. And more 
 recently the delicate methods of modern petrography have in the 
 same country been first made to establish the identity between 
 ancient volcanic rocks and those of the present. The world is 
 now but beginning to follow in this respect the lead set by 
 Allport, J, A. Phillips, Judd, Bonney, Rutley, Marker, Cole and 
 others in Great Britain. A few Englishmen, like Mallet or 
 Hicks, have considered the oldest volcanic rocks either as orig- 
 inally different from those now produced, or as characteristic of 
 some definite geological horizon, but, on the whole, the British 
 school of geology, more than any other, recognizes a practical 
 uniformity in the nature of volcanic action and products fi i n the 
 Archean to the present.' 
 
 In Germany and France volcanic rocks {Ergussgesteine) are 
 recognized as abundant in certain of the earlier geological form- 
 ations. Nevertheless there is in these countries a prevailing ten- 
 dency to separate Tertiary from pre-Tertiary rocks of this class 
 as things originally and genetically distinct." It is noticeable 
 that the earlier schemes of rock-classifici»lion, like those of 
 Brongniart, Haiiy, Cordier and K. C. von Leonhard, are quite 
 purely mineralogical. The division of older and younger, or 
 paleo- and neo-volcanic rocks is to be in part accounted for by 
 the concentration of these masses in central Europe within the 
 Permo-Carboniferous and Tertiary periods and their comparative 
 
 ' See "The History of Volcanic Action in the Area of the British Isles," Presiden- 
 tial Address by Sir Archibali Geikie, F.R.S., etc. Quart. Jour. Geol. Soc, Vols. 47 
 and 48, 1891-2. 
 
 'Roth: Sitzber. Berl. Ak. 1869, p. 72, et stq. Zirkel: Lehrbuch der Petro- 
 graphie, 2d. ed., Vol. I., p. 838, 1893. 
 
 1 
 
 ^■:A' I ^Jtj ' J J ^L-,'.lHJii^l) i y 
 
«j t-[»V'fcJ: f i» *S "^l « 
 
 ' 
 
 ^. 
 
 6 THE JOURNAL OF GEOLOGY. 
 
 rarity in Mcsozoic times. It is, however, also connected with 
 thcWcrncrian tloctrine of the non-recurrence of certain physical 
 conditions in the earth's tlcvelopnient, as contrasted with the 
 uniformitarianism of Hutton and Lyell. The absence of vol- 
 canic types in Europe which serve to bridge over the sharp 
 contrast between those of the Carboniferous and Tertiary, 
 is being rapidly compensated Iv the discovery of such rocks in 
 other regions. Fortunate finds .f even pre-Cambrian lavas so 
 perfectly preserved as to demonstrate their practical identity, 
 both chemically and structurally, with recent products is tending 
 to weaken the old distinction on the continent. There are now 
 many signs of j)rogress toward the idea that the characters 
 regarded as belonging peculiarly to the older effusive rocks arc 
 better explained through changes subsequent to their solidifica- 
 tion. 
 
 Thus Ludwig in 1861,' Vogelsang in 1867,' »"'^ Lossen in 
 1869,3 regard some quartz-porphyries as only devitrified glasses, 
 identical with those of modern volcanic regions; Kalkowsky,* 
 and recently Sauer' and Vogel,* have also brought convincing 
 proof that such is often the case. 
 
 Gllmbel says : " Es scheint in dieser Bezichung denn doch eher gerecht- 
 fertigt, zunachst das petrographisch Gleiche auch gleich zu bezeichnen, als in 
 einzelnen FSllen ein neues Princip, das des Alters, in die Petrographie einzu- 
 ftlhren, welches bei den meisten Ubrigen Fallen nicht verglichen und berlick- 
 sicht werden kann ; " ' 
 
 And Rosenbusch also remarks : 
 
 " Man hat den geologischen Alter der Eruptivgesteine bisher ein hSheres 
 bestimmendes Moment fUr die structurelle und mineralogische Ausbildung 
 dieser zugeschrieben als demselben in Wirklichkeit zukommt."' 
 
 ■ Erl. z. geol. Karte Hessens, Bl. Dieburg, p. 56, 1861. 
 
 'Philosophie der Geologie, pp. 144-146, 1867. 
 
 3Abh. Berl. Ak., 1869, p. 85. 
 
 ^ TscHERMAK's Min. Mitth, pp. 31 and 58, 1874. 
 
 ^Erl. zur geol. Specialkarte Sachsens, Bl. Meissen, pp. 81-91, 1889 
 
 ' Abh. geol. Landesanstalt von Hessen, vol. ii., p. 38, 1892. 
 
 ' GrundzUge der Geologie, 1888, p. 85. 
 
 'Die massigen Gesteine, 2d. ed., 1887, p. 4. 
 
■^ 
 
 THE DISTRllWriON OF ANCIENT VOLCANIC ROCKS, 7 
 
 lie nevertheless adheres to the division between paleo- and 
 nco-volcanic rocks, although he says that about llieir only differ- 
 ence iu that the latter can often be found to belong to volcanoes 
 (i. e., volcanic mountains) which are themselves so extremely 
 subject to removal by erosion.' 
 
 Admirable observations on the use of age in rock-classifica- 
 tion are made by M. Neumayr. He says: 
 
 " Wohl IUUS8 dcr Geolog dem Alter der Gesteine Rechnunx traKeii, aber 
 diese HerlU ksichtigung ist eine von der Heschreibung uiid Eintheilung der 
 Gesteine durchaus unabhilngige Sache. Wie schon oft betont worden ist, ist 
 uriter den Sedimentargesteinen das richtige Prinzip schon durchgeflihrt, 
 dass man von Kalken, von Dolomiten, Sandsteinen, etc., des Silur, des Jura, 
 des TertiSr spricht, ohne die verschiedenalterigen Gesteine von gleicher 
 lieschafifenheit init eigneii Namen zu belegen ; genau in derselben Wcise 
 wird man auch mit den Miissengesteinen verfahren mlissen. Auf einen 
 solchen Standpunkt wird und muss die Gesteinslehre ebenfalls gelangen ; sie 
 wird ihre Unterscheiduri'- ler Felsarten nur nach petrographischen Merk- 
 malen und petrographischcr Methodc vornehmen, und die Altersbestimmung 
 derGeologieliberlassen, was natUrlichnicht ausschliesst.dassbeide Forschungs- 
 gebiete von einer und derselben Person beherrscht werden."' 
 
 In Belgium we see de la ValleSe Poussin in 1885 writing of 
 " Les anciennes Rhyolites dites Eurites," ^ just as they would in 
 England ; while in France the recognized leader in petrograph- 
 ical usage, Michel-L6vy, although he still distinguishes " roches 
 porphyriques ante-tcrtiaires," from "roches trachytoides tertiaires et 
 post-tertiaires," expresses himself in regard to the futility of the 
 age distinction in rock nomenclature as follows : 
 
 "On voit, par tout ce qui pr^c^de, qu'il est n^cessaire d'asseoir une classi- 
 fication p^trograjihique rationnelle sur des faits contingents, independents 
 d 'hypotheses g^ogdn^tiques, et que la consideration de I'ftge des roches, k ce 
 point de vue, est aussi hypoth^tique que celle de leurs conditions degisement 
 dans les profondeurs ou k la surface. Etant donn6 un ^chantillon de pro- 
 venance inconnue, il est indispensible et il est possible de le nommer et de le 
 d^crire sans amphibologie. II n'est possible d'en determiner, avec certitude 
 et precision ni le gisement ni I'ftge geologique."* 
 
 •lb., p. 6. 
 
 'Erdgeschichte, Vol. I, p. 599. 
 
 sBull. de I'Acad. roy. de Belgique (3) Vol. 10, No. 8, 1885. 
 
 < Structures et Classification des Roches Erupt! ves, p. 34, 1889. 
 
 .'.a^^^^aygi^' ^M ^ Ljj^ ^w^^ M ^^ ^^u^^ig grg 
 
8 THE JOURNAL OF GEOLOGY. 
 
 In Scandinavia, if we judge from the most recent publica- 
 tions, there is, in spite of the general adherence to German 
 nomenclature, a fuller recognition of the similarity between 
 ancient and modern volcanic rocks than is to be found in any 
 other part of Europe except England. 
 
 On the western coast of Norway, Reusch describes old lava 
 flows of quartz-porphyry and more basic diabase amygdaloids 
 which show spheroidal parting on a large scale due to cooling. 
 These rocks are accompanied by tuffs and breccias which, in 
 spite of subsequent dynamic action, still show their original 
 characters. In one case, on the island of Gjeitung, occurs a 
 deposit of pumice bombs cemented by what is now a chlorite 
 schist.' 
 
 In Sweden Hogbom describes the general distribution of 
 post-Archean (Algonkian) eruptive rocks, many of which bear 
 unmistakable evidence of volcanic character.' Otto Norden- 
 skjold assigns the beautiful flow-porphyries and amygdaloids of 
 the Elfdalen region to the same horizon, while he concludes that 
 most of the Halleflintas of southeastern Sweden (Smiland) are 
 surface lavas. He finds in them such well-developed fluidal, 
 eUtaxitic, rhyolitic and perlitic structures that they may be 
 regarded as old rhyoHtes or devitrified obsidians.^ The probably 
 much younger and still glassy rhyolites of the gneiss area of 
 Lake Mien are described by N. O. Hoist.* 
 
 In Russia Tschernyschew describes from the central Urals, 
 many types of eruptive rocks, and among them both acid and 
 basic volcanics of great antiquity, accompanied by their agglom- 
 erates, breccias and tuffs.' 
 
 In America the recognition of the true character and relation- 
 ships of ancient volcanic rocks has been greatly retarded both 
 
 'Bdmmeloen og Kannoen, pp. 109, 122, and 403, 1888. 
 "Geologiska Foren. i Stock. Forh., Vol. 15, p. 209, 1893. 
 3 Bull. geol. See. Upsala, Vol. I, Nos. I and 2, 1893. 
 * Afhandl. Sverig. geol. Undersok. Ser. C, No. no, 1890. 
 SAllgemeine geologische Karte von Russland, Bl. 139, Central UraU. Text 4° 
 pp. 323 and 333, 1889. 
 
"Sft-itjS.'^P 
 
 THE DISTRIBUTION OF ANCIENT VOLCANIC ROCKS. 9 
 
 by the adherents to the so-called metamorphic school, like Dana, 
 Logan, Rogers, Lesley and Winchell, who fail to find among 
 the ancient foliated crystallines anything beside altered sedi- 
 ments, but perhaps even more by the influence of that most 
 extreme of all Wernerians, Dr. T. Sterry Hunt. While antithet- 
 ically opposed to the members of the metamorphic school in his 
 notions of lithological character as an index of geological posi- 
 tion, Dr. Hunt had in common with them the conviction that the 
 ancient lavas and volcanic breccias, tuffs and ash-beds were 
 normal aqueous deposits. The basic volcanics of eastern North 
 America enter so argely into his " Huronian," and the acid 
 types so largely into his " Arvonian," that his writings may still 
 be used as suggestive of localities where ancient effusive rocks 
 may be sought for.' 
 
 But there have not been wanting those among the earlier 
 American geologists who have clearly recognized the igneous 
 members of the ancient crystalline formations, in spite of their 
 disguised character. Prominent among them are E. Hitchcock, 
 Emmons, Lieber, Foster and Whitney. Not only the igneous, 
 but the volcanic (surface) character of the Lake Superior lavas 
 has been maintained by Pumpelly,' Wadsworth,3 Irving,* Van Hise^ 
 and the present writer.* In Canada igneous rocks have always 
 been regarded abundant in the oldest formations, while the 
 volcanic character of some of them has been insisted on by 
 Selwyn ? and mentioned by other members of the Canadian Geo- 
 logical Survey. A looseness of usage is, however, observable in 
 some of these reports, where " volcanic " is made synonymous . 
 
 'See: Presidential Address, Am. Assn. Adv. Sci., 1871 ; Proc. Am. Assn. Adv. 
 Sci., 1876, p. 211-211; Azoic Rocks, 1878; Am. Jour. Science, May, 1880; Mineral 
 Physiology and Physiography, Chaw IX., 1886. 
 
 "Geology of Michigan, Vol. I, 1873. 
 
 3Bull.Mus. Comp. Zool,, Vol. 7, p. iii, 1880. 
 
 « Monograph v., U. S. Geological Survey, 1883. 
 
 5 Bull. Geol. Soc. Am., Vol. 4, p. 435, 1893. 
 
 *Bull. U. S. Geol. Surv., No. 62, p. 192, et seq., 1890. 
 
 'Report of the Geol. Survey of Canada for 1877-78. A, p. 5. Trans. Roy. Soc. 
 of Canada, Vol. i, p. 10, 1882. 
 
 
 i 
 
 '4 
 
 I 
 
lfMft«MMHM%iM 
 
 10 
 
 THE JOURNAL OF GEOLOGY. 
 
 with " igneous." ' In the eastern United States Wadsworth was 
 the first to declare for the volcanic origin of the felsites and 
 tuffs in the Boston basin which, through the influence of Hunt's 
 doctrine had, after Hitchcock's time, come to be explained as 
 sediments. To Dr. Wadsworth also belongs the honor of having , 
 been the first geologist on this continent to insist on the original 
 identity of these old lavas and pyroclastics with the recent vol- 
 canic rocks of the Cordilleras.' There is little doubt that the 
 finely preserved ancient volcanic material in the eastern crystalline 
 belt and elsewhere will, when it is adequately studied, finally 
 bring to this opinion most American geologists. If we as yet 
 know little of the extent and distribution of our ancient volcan- 
 ics, we are at least bound by no traditions to artificial and useless 
 age distinctions, and may freely follow the lead of our English 
 colleagues. 
 
 CRITERIA FOR THE RECOGNITION OF ANCIENT VOLCANIC ROCKS. 
 
 It is a self-evident proposition that the identification of 
 certain rocks as volcanic products is in no way dependent upon 
 their present association with a recognizable crater or volcanic 
 mountain. By volcanic rocks we understand igneous or pyro- 
 clastic material which has solidified or been deposited at, or very 
 near the earth's surface. It is of little moment whether or not 
 it was ever piled into conical mountains. That the rocks them- 
 selves bear witness to their origin and conditions of formation is 
 sufficient. The successive effects of erosion on the easily removed 
 . volcanic mountains has been so often graphically 'iescribeda that 
 no further reference to the subject is here necessary. If the 
 Eocene or Triassic volcanoes have so disappeared as to leave 
 
 "For instance, Ells in his "Geology of the Eastern Townships " (Can. Kept, for 
 1886, J.) speaks of pre-Cambrian rocks as "volcanic" and "plutonic," but enumerates 
 only granite, diorite and serpentine. 
 
 -Bull. Mus. Comp. Zool., Vol. S, i879, P- 277 't ^'9; and Azoic System, ib.. Vol. 7, 
 1884, p. 429- 
 
 3 See DE LA Beche: Geological Observer, pp. 526-537. i8Si- M. Neumayr : 
 Erdgesch'ichte, Vol. I, pp. 202-204, 1887. W. M. Davis: "The Lost Volcanoes of 
 Connecticut," Popular Science Monthly, Dec, 1891. 
 
 J!i 
 
 •h 
 
n 
 
 THE DISTRIBUTION OF ANCIENT VOLCANIC ROCKS. 1 1 
 
 only traces of their original forms, what may we expect of those 
 of Paleozoic or Archean times? 
 
 On the other hand, the association in dissected volcanic 
 regions of the effusive rocks with correspondingly abyssal types 
 naturally suggests that volcanoes may have once surmounted 
 many areas of coarsely granular ancient igneous rocks. As this, 
 however, cannot be proved, only such regions are here con- 
 sidered as yield rocks of unmistakably surface origin. 
 
 Again, ancient volcanic rocks may have been subjected to 
 metamorphosing processes severe enough to have destroyed 
 most of their original characters. In such cases, patient study 
 and a careful weighing of all evidence is necessary to decide 
 their origin, and even that may not avail. Igneous rocks may 
 be so altered as to be indistinguishable from metamorphosed 
 sediments, but it many cases where this at first appears to be the 
 fact, some decisive clue may be discovered. 
 
 In establishing the volcanic nature of rocks occurring in 
 ancient and more or less crystalline terrains, attention must be 
 given to several different sets of characters. The field relations 
 must be carefully studied and the material collected on the spot 
 and afterward studied in the laboratory. The criteria for decid- 
 ing on their igneous and volcanic origin may be arranged as 
 follows : 
 
 I. If the rocks are igneous, whether abyssal or surface, they 
 will: 
 
 composition to certain well 
 
 2. 
 
 Conform in chemical 
 established types ; 
 
 Show an association of petrographical types which, 
 both chemically and mineralogically, follow the laws 
 of consanguinity. 
 II. If they are volcanic : 
 
 I. They may be found in the field to occur in distinct 
 sheets, flows or necks ; 
 
 They will have produced very little or no contact 
 action in the adjoining rocks ; 
 They may include irregular fragments of other rocks. 
 
 2. 
 
 3- 
 
 •I- 
 
 II 
 
 
 X-i 
 
 II 
 
 -•^Mt^ 
 
7 
 
 It THE JOURNAL OF GEOLOGY. 
 
 III. If they are volcanic : 
 
 1. They may appear to be striped, banded, or pseudo- 
 '• stratified" conformably to adjoining sedimentary 
 deposits ; 
 
 2. They will probably be accompanied by fragmental 
 (pyroclastic) material, which may or may not itself 
 be really stratified. Such material will vary greatly 
 in coarseness, containing bombs, agglomerates, brec- 
 cias, tuffs, sands and ashes. The characteristics of 
 
 these are : 
 
 i) indiscriminate mixture of all sizes and shapes of 
 
 fragments ; 
 
 2) material of same kind as the igneous rocks; 
 
 3) cement, either finer fragmental material (tuff- 
 breccia) or lava (flow-breccia); 
 
 4) very angular shape of smallest fragments (micro- 
 scopic glass sherds). 
 
 5) if ancient volcanoes were on the shore-line, such 
 material may have been immediately worked over 
 by water and interbedded with more or less 
 normal aqueous sediments. 
 
 IV. Most important of all, however, is the identification of 
 those characteristic structures known to originate only 
 in glassy, half-glassy or very fine grained porphyritic 
 rocks, solidifying at the surface, or in very narrow dykes 
 where solidification has been rapid. These will be found 
 to be very persistent and can usually be identified under 
 the microscope in spite of devitrification, alteration, or 
 even a considerable degree of dynamometamorphism. 
 The most common of these structures are : 
 
 1. a vesicular, scoriaceous, pumiceous or amygdaloidal 
 
 structure ; 
 
 2. a sharply defined, small porphyritic structure with a 
 glassy, half-glassy or felsitic (cryptocrystalline) base ; 
 
 3. a spherulitic structure, due to either large or small 
 lithopysae, hollow spherulites, or compact spherulites. 
 
 
THE DISTRIBUTION OF ANCIENT VOLCANIC ROCKS. 1 3 
 
 arranged either irregularly, or in more or less discon- 
 tinuous bands or layers ; 
 
 4. a flow structure, produced either by the elongation of 
 vesicles or the parallel arrangement of constituents 
 or crystallites. It may also be produced by the 
 interlacing of different colored magmas (eutaxitic 
 structure) ; ^ 
 
 5. corroded phenocrysts, quartz with embayments, or 
 skeleton crystals due to rapid and imperfect growth ; 
 
 6. microscopic spherulites, globulites, trichites, crystal- 
 lites, real or devitnfied glass inclusions, quartz with 
 orientated siliceous aureoles, axiolites, etc.; 
 
 7. perlitic structure, wholly or partly devitrified. 
 Although some of these structures may occasionally occur in 
 
 dykes or other igneous rocks which have rapidly solidified beneath 
 the surface, they are nevertheless so essentially characteristic of 
 effusive lavas, that, in lack of any evidence to the contrary, they 
 may be regarded as fairly safe guides in establishing the effusive 
 nature of rocks. This evidence is beyond doubt, if such rocks 
 are accompanied, as they generally are, by ash material. 
 
 While a single one of these characteristics may not be suffi- 
 cient to Identify a volcanic occurrence, many, if not all of them, 
 will be found to occur together, and only in rare instances will 
 it be found that some of them, at lea'st, have not survived the 
 vicissitudes of metamorphism. That many regions in the ancient 
 crystalline belt of the Appalachian system exhibit most of them 
 in great perfection is now well known. It is only a misinterpre- 
 tation of these characteristic features of volcanic rocks, due to 
 a lack of acquaintance on the part of observers with their recent 
 analogues, that has prevented their recognition long ago. Thus, 
 by those who have heretofore described these rocks as sedi- 
 ments, both secondary cleavage, and the banding due to flow or 
 parallel spherulitic layers have been mistaken for stratification ; 
 spherulites have been erroneously regarded as concretions ; and 
 the accompanying pyroclastics, as normal conglomerates or 
 slates. 
 
 if 
 
 11 
 
M 
 
 THE JOURNAL OF GEOLOGY. 
 
 It is the purpose of the writer in the present paper to main- 
 tain that in the great crystalline belt of eastern North America, large 
 areas of volcanic rocks occur, and that these, in spite of their great 
 age, are in all respects the same as modern volcanic materials, save 
 for alterations subsequent to their original formation — among which 
 alteratiom devitrification lias been one of the most important.^ 
 
 DISTRIBUTION OF VOLCANIC AREAS ALONG EASTERN NORTH 
 
 AMERICA. 
 
 I shall now proceed to summarize the present state of our 
 knowledge of these volcanic areas, as far as they belong to the 
 Eastern or Appalachian crystalline belt, omitting all reference 
 to the central Canadian, Lake Superior, Missouri, or other more 
 western regions of similar nature. In this review I shall com- 
 mence with Newfoundland and follow them southwest, parallel 
 to the coast. 
 
 Eastern Canada. — In a recent comparison between the Eozoic 
 and Paleozoic rocks of eastern America and western Europe, 
 Sir William Dawson says that the Huronian was evidently a 
 coarse marginal deposit, accompanied by abundant volcanic out- 
 breaks, similar to those which occurred about the same time in 
 Wales. He is also confident that many of the bedded Huronian 
 rocks are really of volcanic origin, being ashes in an altered state." 
 In the same paper he mentions volcanic rocks, both lavas and pyro- 
 clastics, as abundant in the Ordivician and Silurian formations 
 of eastern Canada. 
 
 The reports of the Canadian and Newfoundland surveys 
 abound in references to rocks of a volcanic character in the 
 early Paleozoic and pre- Paleozoic horizons. These references 
 are, however, always purely those of a field-geologist engaged 
 in a rapid reconnaissance. The frequent use of such field terms 
 as felsite, porphyry, trap, amygdaloid, agglomerate, breccia and 
 ash suggest a vast development of contemporaneous volcanic 
 
 ' On the nomenclature of these ancient and devitrified lavas, see Miss Florence 
 Bascom's paper, this Journal, Vol. I., No. 8, p. 825, Nov.-Dec. 1893. 
 
 » Quart. Jour. Geol. Soc, Vol. 44, p. 801, 1888. 
 
 
 ^% 
 
■ii- 
 
 THE DISTRIBUTION OF ANCIENT VOLCANIC ROCKS. I 5 
 
 materials, but thus far no petrographcr has attempted to study 
 systematically either the field or microscopical relations of any 
 area of these interesting rocks. A very broad and interesting 
 field is thus seen to be awaiting investigation in Newfoundland, 
 Gasp^, New Brunswick, Nova Scotia and the Eastern Town- 
 ships. 
 
 Professor J. B. Jukes, in his "Geology of Newfoundland," 
 describes old lava flows and accompanying pyroclastic deposits 
 as very abundant, especially on the peninsula of Avalon, which 
 forms the eastern part of the island.' His observations are con- 
 firmed by the later reports of Murray and Howley, who agree 
 that the western part of this peninsula was the scene of extraor- 
 dinary volcanic activity in very early times." 
 
 In his three reports on the eastern portion of Cape Breton, 
 Fletcher describes the Ste. Anne, Boisdale, Coxheath, East Bay 
 and Mira Hills, as composed largely of ancient (pre-Cambrian) 
 volcanic rocks, an.ong which felsites of all colors, felsite-por- 
 phyries, felsite breccias and amygdaloids abound.^ Similar 
 rocks appear also to extend up into, and to form an important 
 part of the Cambrian, Silurian and Devonian formations. In a 
 later report on the northern part of Cape Breton, Fletcher ♦ finds 
 that the greater part of the northern peninsula is also composed 
 of " felsites," but the petrographical distinctions of both Fletcher 
 and Gilpin ^ are so indefinite that a variety of coarsely crystal- 
 line rocks seem to be embraced in this general designation. In 
 describing the Mira "felsites," Fletcher mentions those of Blue 
 Mountain and Gull Cape, near Louisburg, as being "globular," 
 or "concretionary," (coarsely spherulitic?) often presenting 
 "single or united spheroids, the concentric layers of which may 
 
 ' Excursions in and about Newfoundland in 1839 and 1840, 2 vols., 1843. Geol- 
 ogy, Vol. 2, pp. 245-341. 
 
 'Reports of the Geological Survey of Newfoundland for 1868-1881. 
 
 3 Reports of the Geol. Survey of Canada, 1875-76, pp. 369-418; ib., 1876-77, 
 pp. 402-456; ib. 1877-78, pp. 1-32, F. 
 
 Mb., 1882-83-84, pp. 1-98 H. , . 
 
 s Quart. Jour. Geol. Soc, Vol. 42, p. 515, 1886. 
 
 
 
 
 ii 
 
 
 —if0r 
 
i6 
 
 THE JOURNAL OF GEOLOGY. 
 
 be removed like the coats of an onion." He also speaks of 
 them as "coarsely brecciated" and "vesicular." A point of 
 some interest is Fletcher's conclusion that "both felsite and 
 syenitic strata are intimately associated as part of the same 
 group of crystalline rocks, differing, not so much in composi- 
 tion as in the degree of crystallization they have been subjected 
 to" («V).' In greatly eroded regions we should expect to find 
 surface volcanic rocks associated with their coarser abyssal 
 equivalents. 
 
 In Nova Scotia proper the best known area of ancient vol- 
 canic rocks is in the northeastern corner of the province, near 
 Arisaig, in Antigonish county. These were considered by Sir 
 William Dawson in 1850 as "metamorphic."' In 1864, Dr. 
 Honeyman described them as vesicular traps, amygdaloids and 
 porphyries, associated with tufa and tufaceous conglomerate.^ 
 In his first report on eastern Nova Scotia, Fletcher describes 
 variegated, vesicular and amygdaloidal "felsites" and "frag- 
 mentary felsites," like those of Coxheath and Louisburg, asso- 
 ciated with "syenite" (hornblende granite) and diorite.* These 
 rocks are regarded as pre-Cambrian, and are particularly devel- 
 oped at Arichat, Cape Porcupine on the Straits of Canso, and in 
 the Sporting, North and Craignish mountains. In the North 
 Mountains the felsites are said to pass gradually into syenite 
 (1. c. p. 14). The gradual blending of the felsite and overlying 
 George River limestone is attributed to "common metamorph- 
 ism," rather than "to contemporaneous volcanic origin or sub- 
 sequent intrusion" (1. c. p. 17). Nevertheless, at Cape Porcu- 
 pine the felsite is regarded as possibly an igneous rock, since 
 "the apparent lines of bedding are like those of a furnace slag" 
 (1. c. p. 25). In the subsequent report of the extension of his 
 explorations southward and westward in Nova Scotia, Fletcher 
 admits the volcanic origin of the felsitic rocks of Arisaig, Doc- 
 
 ' Quoted by Gilpin : Quart. Jour. Geol. See, Vol. 42, p. lib. 
 
 "Quart. Jour. Geol. Soc, Vol. 6, p. 347, 1850. 
 
 3 lb., Vol. 20, p. 333, 1864. 
 
 « Report of the Geol. Sun/ey of Canada, 1879-80, F. 
 
TJfE niSTRlRUTION OF ANCIENT VOLCAX/C ROCKS. 1/ 
 
 tor's Brook, Georpeville, Blue Mountain and Kast River of St. 
 Mary's. These arc quite like the Cape Breton and Cape I'orcu- 
 pine rocks, and carry copper, as they do in South Mountain, Pa., 
 and on Lake Superior. He gives the age of these eruptions as 
 probably pre-Cambrian, although at Arisaig they may be of any 
 age older than Medina. Similar volcanic eruptions occur in all 
 strata up to the base of the Carboniferous.' In his last report 
 covering Pictou and Colchester counties, the same author 
 describes Cambro-Silurian porphyries, agglomerates, fragmental 
 felsites, breccias and amygdaloids from Moose and Sutherland 
 rivew. A dyke-like mass of volcanic breccia occurs on Sam 
 Cameron's brook. Similar volcanic products arc also very 
 apparent in the Devonian of these two counties, among the most 
 interesting of which are the syenitic granites overlaid by thick 
 volcanic deposits at the east end of the Cobequid Hills, as 
 described by Dawson.' The well-known traps of northwestern 
 Nova Scotia, along the Bay of Fundy, which furnish the beauti- 
 ful zeolites and other minerals, are of Triassic age. 
 
 In New Brunswick and the Gaspe Peninsula, old volcanic 
 rocks, like those of Newfoundland and Nova Scotia, are exten- 
 sively developed. Ells and Low mention amygdaloidal traps and 
 porphyries cutting various strata of Gaspe, up to and including 
 the Devonian.3 Felsitic rocks, similar to those which are better 
 known further to the south, are rather vaguely mentioned by 
 Robb in northern New Brunswick.* Ells, in his report on the 
 same region in 1879-80, clearly describes as volcanic both acid 
 and basic rocks. A vast area of felsite, petrosilex, porphyry 
 and breccia, like that near St. Johns, is developed in the upper 
 Nipisiguet river and lake Nictor. Another like it extends 
 from the upper Upsalquitch river along Jacket river to the 
 bay of Chaleur, while great masses of basic volcanics (amyg- 
 
 'Ib., 1886, p. 
 
 •Acadian Geology, 1878, suppl., p. 79. 
 
 Report of the Geol. Survey of Canada, new ser., Vol. 5, 1890-qi, P. pp. 147-166. 
 »lb., 1882-83-84, E, and F. 
 *lb., 1870-71, p. 245. 
 
 .H 
 
i8 
 
 THE JOURNAL OF GEOLOGY. 
 
 daloids, aphanitcs, etc.) occur around the head of the Bay ol 
 Chaleur and Dalhousie, as well as on the upper Upsalquitch and 
 Klni Tree rivers. Many of these rocks are pre-Cambrian, while 
 others cut the Silurian strata.' Great sheets of contemporane- 
 ous trap arc also found by Ells in the Silurian, and to a very 
 small extent in the Devonian, along .he north shore of the Bay 
 of Chaleur. Bailey explored parts of northern and western New 
 Brunswick, especially in Carolton, York and Victoria counties, 
 and found porphyries, felsites and amygdaloids, intrusive in the 
 Silurian and older formations in Canterbury, Woodstock and 
 Kent townships, near the St. Johns river.* Still later Bailey 
 and Mclnnes continued similar explorations, and found signs of 
 intense volcanic action in the Niagara limestone at Pointe aux 
 Trembles, and a great development of acid and basic surface 
 rocks near the Aroostook river and at Presqu'ile and Haystack 
 mountain in Maine.' The same is true near Tobique lake, 
 farther to the northeast. 
 
 As early as 1839, Gesner describes the volcanic rocks along 
 the Bay of Fundy, in southern New Brunswick, as belonging 
 to several distinct horizons." In 1865, Bailey, Matthew and 
 Hartt distinguished two groups mainly of volcanic origin, to one 
 of which, the "Coldbrook," they assigned a Huronian, and to 
 the other, the " Bloomsbury," a Devonian age.* In 1872, 
 Bailey and Matthew, after a season's field-work with Dr. T. 
 Sterry Hunt, united the Coldbrook and Bloomsbury groups on 
 purely lithological grounds, and for the same reason joined with 
 them two other volcanic series — the Coastal and Kingston 
 groups— exposed at other localities in southern New Bruns- 
 wick.* The petrographical characters of these rocks were those 
 regarded by Hunt as sufficient demonstration oi Huronian age. 
 The acceptance of this fallacious principle exercised a distinctly 
 
 • lb., 1879-80, pp. 35 to 42. 
 
 «Ib., 2882-83-84, G. pp. 15 and 20; ib., 1885, G. pp. 22 and 28. 
 
 3 lb., 1886, N. pp. 14-1S ; and ib., 1887-88, M. pp. 32 and 47. 
 
 4 First Report on the Geological Survey of the Province of New Brunswick, by 
 Abraham Gesner. 87 pp. 1839. 
 
 5 Observations on the Geology of Southern New Brunswick. 1865. 
 « Report of the Geol. Survey of Canada, 1870-71, pp. 57-I33' 
 
 
1 
 
 THE DISTRinUTlON OF ANCIENT VOLCANIC ROCKS. 1 9 
 
 retarding effect on the deciphering of New Brunswick geology. 
 Numerous occurrences of fclsite, porphyries and aniygdaloids 
 were described between Muscpiosli Harbor and Loch Lomond, 
 near the city of St. Johns, and along the line between Kings 
 and Queens counties (Coldbrook and Bloomsbury groups). 
 Similar rocks were traced from L'Etang ILirbor, near I'assama- 
 quoddy Bay, along the edge of the Bay of Fundy to Shepody, 
 in Albert Coiinty (Coastal group); and finally, a belt of ana- 
 logous composition was described between the Long Reach of 
 the St. Jol MS river and Mace's bay (Kingston group). These 
 rocks were it this time, however, on account of Hunt's influ- 
 ence, united with their associated sediments, and nothing is said 
 about their volcanic character. These authors were forced to 
 regard similar rocks on the shores of Passamaquoddy bay as 
 Silurian, because of associated fossils, in spite of their litholog- 
 ical identity with the " Huronian." These they called the Mas- 
 carene scries,' 
 
 Four years later the same authors united the Kingston and 
 Mascarene groups and regarded both as upper Silurian." In a 
 report of the pre-Silurian rocks of Albert, eastern Kings, and 
 St. Johns counties. Ells gives some clear statements relative to 
 the volcanic rocks of southern New Brunswick. He says : 
 
 " In their lithological aspect, the rocks forming the southern metamorphic 
 belt present great diversity. Their general character is of two kinds— altered 
 sedimentary and volcanic. * * * In the latter we include the great mass 
 of petrosiliceous rocks, so called, with breccias and other ash rocks, which 
 in places show bedding, but this is often so obscurely marked as to be exceed- 
 ingly doubtful. ♦ * * Near the contact of the volcanic and sedimentary 
 rocks we find an extraordinary development of generally coarsely crystalline 
 diorites and syenites, which would seem to form the basal portion of the vol- 
 canic part of the series."' 
 
 A report on the same rocks was published at the same time 
 by Bailey, who divides them into a feldspathic, syenetic and 
 gneissic group, including limestones, serpentines, and dolomites 
 
 'lb., pp. 144-158. 
 
 Mb., 1874-7S, pp. 85-89. 
 
 3lb., i877-78,D. p. 3. 
 
 
THE JOURNAL OF GEOLOGY. 
 
 (Laurcntian); a felsitc-pctrosilcx group (Lower Huronian or 
 Coldbrook;; and a schistose, chloritic micaceous group (Upper 
 Huronian or Coastal).' The results of all their work on the 
 rocks of southern New Brunswick is summarized by Bailey, 
 Matthew and Ells, with a general geological map in three 
 sheets." 
 
 That portion of the Province of Quebec lying south and 
 east of the St. Lawrence is called the Eastern Townships. We 
 have already considered that portion of it composing the Gasp* 
 peninsula. The portion lying west of Maine and north of New 
 Hampshire and Vermont was supposed by Logan to be wholly 
 occupied by rocks of the Quebec Group. In 1879, Dr. Selwyn 
 divided the rocks of this zone into three groups, which he 
 defined as lower Silurian; volcanic (probably lower Cambrian); 
 and crystalline (probably Huronian). The lower of these divis- 
 ions forms an anticlinal axis extending from Lake Memphrema- 
 gog to L'Islet County, 150 miles. It contains a great variety 
 of altered sedimentary beds, associated with "diorites, doler- 
 ites, serpentines, amygdaloids, and volcanic agglomerates," 
 regarded by Hunt as altered sedimentaries. The second divis- 
 ion, said to be intimately related to the last, is largely composed 
 " especially on the southeastern side of the axis, of altered volcanic products 
 both intrusive and interstratified, the latter being clearly of contemporaneous 
 origin with the associated sandstones and slates." 
 
 These rocks are designated as 
 "dioritic, epidotic, and serpentinous breccias and agglomerates; diorites, 
 dolerites and amygdaloids holding copper ore; serpentines, felsites and 
 some fine grained granitic and gneissic rocks." 
 
 They are especially developed along the contact of the last- 
 mentioned group, of which they "may be merely the upward 
 extension." 3 In a later paper on the Quebec Group, Dr. Sel- 
 wyn considers these volcanic rocks thoroughly from the English 
 point of view. He says : 
 
 • lb., DD. p. 2. 
 
 » lb., 1878-79, D. p. 26. 
 
 3 lb., 1877-78, A. pp. 5-9. 
 
 "^ 
 
THE DISTRIIiVriON OF ANCIENT VOLCANIC ROCK'S. 21 
 
 " I would alsi> Buhmit that neither a RchiiitiiRe nor a bedded utructure can he 
 accepted as proof of a non-i>(neouH or volcanic «)rif(in, and that a once mas- 
 sive lava-flow, whether auKitic or feldspathic, is as likely, through presiure 
 and metaniorphism, to assume a schistose structure as are ordinary sedi- 
 mentary slriJta. It is, I am aware, not in accordance with generally receiveil 
 ideas on the nature of ancient igneous rocks to supjiose they can be schistose 
 and stratified, especially so in America, where volcanic agency in the earlier 
 geological periods has been almost entirely ignored, and all those rocks 
 which by their microscopic characters and chemical conifiosition, and by 
 their geological associations and relations, point to volcanic agency as the 
 cause of their formation, have been said to be ' not if^'tteoiis, bitf tnelumorfihic 
 in origin; a description which, it seems to me, is decidedly self-cimtradic- 
 tory." • 
 
 Sclwyn later again maintained his volcanic group, and pub- 
 lished microscopic descriptions of some of its rocks (cjuartz- 
 porphyry and porphyrite) by Adams.» Little or nothing is added 
 to our knowledge of the strictly volcanic rocks by the two sub- 
 sequent reports on the geology of the Eastern Townships by 
 Ells.3 
 
 The recognition of ancient volcanic rocks in the United 
 States is far behind that which prevails in Canada. This, as 
 has already been pointed out, is due to the influence of so-called 
 "metamorphic" ideas, or more properly to the Wernerian doc- 
 trine, that every rock showing any foliated or parallel structure 
 is sedimentary. 
 
 Nexv England. — Very little definite information can be gath- 
 ered from the earlier reports on the geology of Maine, by Jack- 
 son and C. H. Hitchcock, regarding the old volcanic deposits. 
 Jackson frequently uses such petrographical terms as "amygda- 
 loidal trap, ribbon jasper, clinkstone porphyry, and breccia com- 
 posed of an infinity of fragments of jasper," in describing the 
 rocks near Eastport and Machiasport, on the Maine coast. He 
 regarded the basic rocks (trap) as eruptive, but the "jasper" as 
 semifused sediments whose lines of stratification weie still pre- 
 
 ' Trans. Roy. See. Canada, Vol. i, p. lo, 1882. 
 
 " Report of the Geol. Survey of Canada, 1880-82, A. p. 2 and pp. 10-14. 
 
 3 lb., 1886, J., and ib., 1887-88, K. 
 
 -.or 
 
22 
 
 THE JOURNAL OF GEOLOGY. 
 
 served.' His descriptions are, however, very suggestive, espe- 
 cially in light of the truly volcanic rocks which have been 
 recently discovered in the older strata of Maine. C. H. Hitch- 
 cock, in his Maine reports, regards the acid volcanic rocks near 
 Machiasport as altered slates, and mentions extensive areas of 
 similar rocks on Mooseh< ad, Portage, Long, and Chamberlain 
 lakes, as well as along the Aroostook and Penobscot rivers, in the 
 interior of the state.* Goodale gives four patches of analogous 
 "siliceous slates" in York county, and five in Oxford county, 
 and J. H. Huntington describes the summit of the diorite south- 
 east of Kennebago lake, in western Maine, as composed of com- 
 pact felsite, which he regards as an eruptive rock.3 The first 
 definite descriptions of ancient volcanic rocks in Maine was 
 given by Professor Shaler, who examined the regions about 
 Eastport and Mount Desert. Near Eastport, and especially on 
 McMaster's island, three types of volcanic material are largely 
 developed : i ) detrital accumulations which have fallen through 
 the air; 2) true lava flows; 3) dykes. They seem to belong to 
 various horizons of Silurian age.* A similar series of interstrati- 
 fied volcanic breccias, lava flows and ash beds are described as 
 forming a large part of Mt. Desert island south of Southwest 
 Harbor, and the Cranberry Isles.' 
 
 The writer has had the opportunity to personally examine 
 the volcanic rocks of the Mt. Desert region, and he is indebted 
 to Professor W. S. Bayley of Waterville, Me., for specimens and 
 slides of the beautiful lavas of Vinal Haven, and to Mr. E. B. 
 Mathews for notes and specim.ens of similar rocks from Mt. 
 Kineo on Moosehead Lake. 
 
 Along the shores of Cranberry Island occur hard jaspery 
 felsites, often porphyritic, and exhibiting such characteristic 
 features of glassy rocks as spherulites, single and in bands, flow- 
 
 ' First Report on the Geology of the State of Maine, 1837, p. 12 and pp. 36-42. 
 
 'Geological Report, 1 86 1, p. 190, and p. 432; also ib., 1863. p. 330. 
 
 sPrpc. Am. Assn. Adv. Sci., Vol. 26, p. 286, 1877. 
 
 ♦Am. Jour, of Science (3d ser.). Vol. 32, pp. 40-43, 1886. 
 
 sEighth Ann. Report U. S. Geol. Survey, pp. 1037, 1043, 1054. 1889. 
 
PHm 
 
 THE DISTRIBUTION OF ANCIENT VOLCANIC ROCKS. 23 
 
 structure, etc., in great perfection, although all trace of the 
 original glass has long since disappeared. The rocks collected 
 by Professor Bayley on the north side of Vinal Haven and on 
 the opposite shore west of North Haven are, according to his 
 field observations, all surface flows or tuffs. Of the nine speci- 
 mens kindly submitted to me for examination by Professor 
 Bayley, one is a medium grained microgranite and all the others 
 
 tiu. I. 
 
 Fig. I. Devitrified glass-breccia from north side of Vinal Haven, Penobscot Bay, 
 Me. Magnified six times. 
 
 are devitrified glassy rocks, which were once either obsidians, 
 glass breccias, or tuffs. No. 94 is a banded flow-felsite, a devit- 
 rified glass with narrow chains of spherulites. No. 100 is a 
 devitrified obsidian containing delicate flow-lines produced by 
 trichites, some zircon crystals, and spherulitic bands in which 
 epidote has been secondarily produced. No. 1 26 is a pale gray 
 felsite containing large round nodules which may be spherulites. 
 Under the microscope it shows a pronounced perlitic structure. 
 These rocks contain spherulitic structures which are not devitri- 
 fication products but original, if we may judge from their abso- 
 lute identity with similar structures in the glassy rocks from 
 Obsidian Cliff. The other five specimens are fine grained vol- 
 
THE JOURNAL OF GEOLOGY. 
 
 canic ashes, most of them composed of very sharply angular 
 fragments of devitrified glass or pumice with beautiful flow 
 structures. The delicate detail produced by trichites in one of 
 these is rather roughly represented in Fig. i. It is not unlike 
 the devitrified glass-breccia described by the writer from Onap- 
 ing river in the Sudbury district.' 
 
 The specimens collected by Mr. Mathews at Mount Kineo 
 on Moosehead Lake, and kindly loaned me for examination, are 
 typical quartz-porphyries or keratophyres, some of which exhibit 
 such perfect and delicate flow-lines that they can be regarded 
 only as devitrified glassy lavas. 
 
 In New Hampshire felsites and quartz-porphyries abound. 
 They were regarded as eruptive by Hitchcock and by Hawes 
 when they occur in dykes, although the latter regarded many of 
 them, especially when interstratified, as sediments fused in situ." 
 There are as yet no published descriptions which make it reason- 
 ably certain that truly volcanic, as contrasted with abyssal 
 igneous rocks, occur within this state. 
 
 The important development of ancient volcanic rocks in 
 eastern Massachusetts, in the neighborhood of Boston, has been 
 more discussed than any other similar region on this continent. 
 An excellent resume of the development of opinion regarding 
 these rocks has been given by Whitney and Wadsworth.» E. 
 Hitchcock held correct views as to the igneous character of all 
 the massive rocks, although he regarded the amygdaloids and 
 some of the apparently stratified felsites as altered sediments. 
 Later the influence of Hunt created a general impression that the 
 greater part of these rocks — even the granites — were of sedi- 
 mentary origin. Wadsworth was the first to successfully combat 
 this idea, and to show that not only were the coarsest massive 
 rocks igneous masses, but even the finer jaspery felsites and their 
 
 ■ Bull. Geol. Soc. Am., Vol. 2, p. 138, 1891. 
 Report of the Geol. Survey of Canada, 1890-91, F. p. 75. 
 
 « See Geology of New Hampshire, Vol. 2, p. 260, and Vol. 3, part IV., Mineralogy 
 and Lithology, p. i?'. '878. 
 
 3 The Azoic System, pp. 398-440, 1884. 1 
 

 THE DISTRIBUTION OF ANCIENT VOLCANIC ROCKS. 25 
 
 accompanying fragmental materials were the products of ancient 
 volcanic action. He maintained that the felsites of Marble 
 Head were merely altered rhyolites which had once been quite 
 like those of the western Cordilleras ; and their banding was flow- 
 structure ; and that they were accompanied by ash beds which 
 he cz!l\&A porodites} Two years later the detailed work of Diller 
 and Benton established the volcanic character of the felsites of 
 Mcdford, Melrose, Maiden, Sangus, Wakefield and Lynn, and of 
 the amygdaloid of Brighton.' 
 
 Other areas of similar rocks occur near Newburyport, and 
 also to the south of Boston at Needham, Dedham, Milton, Blue 
 Hill, Hingham, Nantasket and Manomet,3 but these have not as 
 yet been so carefully examined as those farther north, although 
 Crosby, in his recent " Geology of Hingham," classes the mela- 
 phyre. porphyrite, and felsite of Nantasket and Hingham as 
 effusive or volcanic rocks, and describes the latter as '• undoubt- 
 edly an ancient, devitrified obsidian."* 
 
 The Middle Atlantic States. — In New York state there are, 
 as far as the writer is aware, no remains of igneous rock which 
 have solidified at the surface. Nevertheless, the isolated and 
 
 ' The Classification of Rocks. Bull. Mus. Comp. Zool., Harvard Coll., Vol. 5, p. 
 282, 1879. It is worthy of note, in view of all the erroneous ideas 1 'at have prevailed 
 regarding the Boston felsites, that as early as 1822. Dr. Thomas Cooper, President of 
 the College of South Carolina, in an article on "Volcanoes and Volcanic Substances" 
 says : " No person accustomed to volcanic specimens can look at the porphyries from 
 the neighborhood of Boston, in my possession, and doubt of their volcanic origin." 
 (Am. Jour, of Science, 1st ser.. Vol. 4, p. 239). 
 
 ""The Felsites and Their Associated Rocks North of Boston," by J. S. Diller, 
 Bull. Mus. Comp. Zool., Vol. VII., p. 165, 1881; and " The Amygdaloidal Melaphyreof 
 Brighton, Mass.," by E. R. Benton, Ph.D., Proc. Bost. Soc. Nat. Hist., Vol. 20, pp. 
 416-426, 1880. The writer is indebted to Mr. Diller for the privilege of examining 
 his collection of slides of the Boston rocks which are in all essential respects identical 
 with those from the coast of Maine, from South Mountain and North Carolina. 
 
 3 E. Hitchcock : Final Report on the Geology of Massachusetts, Vol. i, p. 150, 
 1841 i W. O. Crosby : Geology of Eastern Massachusetts, pp. 79-95. 1880. 
 
 « Proc. Bost. Soc. Nat. Hist., Vol. 25, p. 502, 1892. See also by the same author : 
 The Lowell Free T.ectures on the Physical History of the Boston Basin, 1889 ; and the 
 Geology of the Boston Basin, Vol. I, Part i. Occasional Papers of the Boston Soc. 
 Nat. Hist., IV., 1893. 
 
26 
 
 THE JOURNAL OF GEOLOGY. 
 
 I 
 
 W\ 
 
 highly differentiated " Cortlandt Series," near Peekskill, presents 
 us with the deeply eroded roots of an ancient volcano, probably 
 of Cambrian or Silurian age, whose superficial parts have entirely 
 disappeared.' The eleolite-syenite area in northern New Jersey 
 is probably of the same character. 
 
 In Pennsylvania and Maryland we find in the South Moun- 
 tain or Blue Ridge, between Harrisburg and the Potomac, one 
 of the most highly diversified and perfectly preserved areas of 
 pre-Cambrian volcanic rocks in the world. Its position is estab- 
 lished as below the Olenellus sandstone ; it presents both acid 
 (rhyolitic) and basic (basaltic) types; it exhibits within limited 
 shear-zones the plainest effects of dynamic action, but its great 
 mass is nevertheless so little changed that each microscopic 
 structure of glassy rocks is clearly recognizable. Skeleton 
 crystals, minute pores and larger vesicles, protoclastic breaking 
 of the phenocrysts, fluidal structures of every kind, trichites, 
 spherulites, axiolites, lithophysal and perlitic parting have lost 
 none of their original sharpness, in spite of the complete devitri- 
 fication of the glassy base. Most of the rocks were probably 
 always wholly or mostly crystalline, but some regions, like the 
 Bigham Copper and Raccoon Creek, display the old spherulitic 
 obsidians and pumice in a manner allowing of no doubt. The 
 pyroclastic materials accompanying these old lavas are also finely 
 developed — ash-beds, coarse and fine flow- and tuff-breccias, etc. 
 The precise centers A eruption within this region have not yet been 
 definitely located, but with what has already been published 
 regarding these rocks and the further details which may be soon 
 expected, no further description of them is here necessary." The 
 entire misunderstanding of these rocks by Rogers, Hunt, Lesley 
 and Fraser, who interpreted them as altered slates and their sec- 
 ondary cleavage as bedding, has greatly retarded the solution 
 
 » Professor Dana once suggested that the Cortlandt massive rocks might have 
 been formed by the metamorphism of " volcanic debris or cinders" (Am. Jour, of 
 Science, 3d sen. Vol. 22, p. 112, Aug. 1881), but he subsequently admitted their intru- 
 sive character (ib. Vol. 28, p. 384, Nov. 1884). See also opinions of the present writer 
 (ib. Vol. 36, p. 268, Oct, 1888). 
 
 "Am. Jour, of Science (3rd ser.) Vol. 44, December, 1892, and Vol. 46, July, 1893. 
 
1 
 
 THE DISTRIBUTION OF ANCIENT VOLCANIC ROCKS. 27 
 
 of the geology of South Mountain, and has for many years 
 invested it with a reputation for complexity which it in no way 
 deserves.' 
 
 In Maryland and Virginia the acid and basic lavas and tuffs 
 of South Mountain are extended southward as an important ele- 
 ment in the composition of the Blue Ridge. They have been 
 somewhat studied by the writer in this region and have been 
 mapped and described by Keith.' This author mentions two 
 quartz-porphyry areas showing flow-structure and tuffs, the 
 larger between Catoctin and Blue mountains in Maryland,' and 
 the smaller near Front Royal in Virginia. He says that the 
 diabase shows many indications of being a surface flow, and that 
 it extends along the Blue Ridge from Maryland half way across 
 Virginia, with an average width of twenty miles. 
 
 Southern States.— MoXc^mc rocks are largely developed in the 
 central portion of both the Carolinas, as may be gathered from 
 the old reports of Emmons and Lieber. During the past sum- 
 mer the writer had the opportunity of examining the belt in 
 Chatham and Orange counties, North Carolina, in company with 
 the State Geologist, Professor J. A. Holmes. The time at com- 
 mand was inadequate for the thorough exploration of the vol- 
 canic belt which skirts the western edge of the Triassic sandstone, 
 but in a drive from Sanford to Chapel Hill an abundance of the 
 most typical ancient lavas, mostly of the acid type, was encoun- 
 tered. On the road from Sanford to Pittsboro purple felsites 
 and porphyries showing spherulites and beautiful flow-structures, 
 and accompanied by pyroclastic breccias and tuffs, were met with 
 two miles north of Deep river and were almost continuously 
 exposed to Rocky river. Here devitrified acid glasses with 
 chains of spherulites and eutaxitic structure were collected, while 
 beyond as far as Bynum on Haw river, four miles northeast of 
 
 1892!^'*^" ^'^^^^^^- Summary Final Report, Penn. Geol. Survey, Vol. i, p. 151, 
 
 "American Geologist, Vol. 10, pp. 366-68, December, 1892. Geologic Atlas of 
 the U. S., Harper's Ferry Sheet {in press). For their distribution in Maryland see the 
 Geological Map of the State, edited by G. H. Williams, and published in the 
 World's Fair Book " Maryland," Baltimore, 1893. 
 
auM 
 
 ^•.^^ra.. 
 
 Fi 
 
 I' 
 
 r 
 
 28 
 
 THE JOURNAL OF GEOLOGY. 
 
 Pittsboro, the only rocks seen were of the same general charac- 
 ter. On the farm of Spence Taylor, Esq., in Pittsboro, a bright 
 red porphyry with flow lines is exposed in so altered a condition 
 that it can be easily cut into any form with a knife, though it 
 still preserves all the details of its structure. It looks not unhke 
 the well known pipe-stone, or Catlinite of Minnesota. Three 
 quarters of a mile beyond Pittsboro on the Bynum road there is 
 a considerable exposure of a basic amygdaloid. South of Hack- 
 ney's Cross Roads there are other excellent exposures of the 
 ancient rhyolites with finely developed spherulitic and flow- 
 structures. Numerous specimens were here collected which 
 place the character of these rocks as surface flows beyond a 
 doubt. Another locality in the volcanic belt was visited on 
 Morgan's Run, about two miles south of Chapel Hill. Here are 
 to be seen admirable exposures of volcanic flows and breccias 
 with finer tuff deposits, which have been extensively sheared into 
 slates by dynamic agency. Toward the east and north these 
 rocks pass under the transgression of Newark sandstone. The 
 accompanying sketch-map (Fig. 2) shows the relations of the 
 above mentioned localities in Chatham and Orange counties, 
 N. C. From still another locality at the cross-road near the 
 northern boundary of Chatham county, fifteen miles southwest 
 of Chapel Hill, Professor Holmes informs me specimens of 
 undoubted volcanic rocks have recently been secured ; he has 
 also sent to me within the past month a suite of similar 
 specimens from Pace's Bridge on Haw river, three miles above 
 
 Bynum. u r- 
 
 In his upper division of the Taconic System in North Caro- 
 lina, Emmons describes numerous beds of " chert or hornstone" 
 intercalated in the slates and sometimes forming isolated bosses, 
 whose origin he is at a loss to account for. He says they are 
 not metamorphic, but does not suggest for them an igneous ori- 
 gin.' The hypothesis that these rocks may also be of volcanic 
 origin is sustained by Emmons' description of "brecciated con- 
 glomerates" associated with the chert beds, which are composed 
 ■Geological Report of the Mull^.d Counties, N. C, 1856, pp. 66-68. 
 
 % 
 
charac- 
 bright 
 ndition 
 ough it 
 t unlike 
 Three 
 there is 
 f Hack- 
 of the 
 id flow- 
 1 which 
 ;yond a 
 jited on 
 I ere are 
 breccias 
 ired into 
 th these 
 le. The 
 s of the 
 counties, 
 near the 
 outhwest 
 imens of 
 ; he has 
 [ similar 
 les above 
 
 rth Caro- 
 irnstone" 
 :d bosses, 
 
 they are 
 leous ori- 
 
 volcanic 
 ated con- 
 :omposed 
 
 THE DISTRIBUTION OF ANCIENT VOLCANIC ROCKS. 29 
 
 of an argillaceous or chloritic base, containing angular chert frag- 
 ments of all sizes up to two feet. He mentions many localities 
 
 ScoU of Miles • 
 
 Fig. 2. 
 Fig. 2. Sketch map of parts of Chatham and Orange counties, N. C, showing locali- 
 ties for ancient volcanic rocks. 
 
 for these rocks, most of which are near the Yadkin river in 
 Davidson, Rowan and Montgomery counties. 
 
 I am informed by Mr. Arthur Keith that he discovered a 
 
ir-mfc; 
 
 30 
 
 THE JOURNAL OF GEOLOGY. 
 
 i! I 
 
 %■' ' 
 
 large area of quartz-porphyry in the Great Smoky Mountains in 
 Yancey Co., N. C, during the past summer. 
 
 The geological reports on South Carolina, by Lieber, describe 
 a great development of igneous rocks which cross the state in 
 the continuation of the North Carolina volcanic belt and which 
 are themselves very probably in part of surface origin. His first 
 report for 1856, which treats of Chesterfield, Lancaster, Chester 
 and York counties, mentions among other more coarsely gran- 
 ular igneous rocks, eurite or quartz-porphyry, aphanitic-porphyry 
 and melaphyre.' The counties of Union and Spartanburg, dealt 
 with in Lieber's second report, are much poorer in igneous rocks, 
 though he here adds the types schistose aphanite and minette. 
 On the geological map of South Carolina, published by the 
 Department of Agriculture in 1883, the belt of aphanitic green- 
 stones and porphyries is shown to be continuous across the state 
 in a southwest direction, and the statement is made that the 
 greenstones predominate toward the north, and the porphyries 
 towrrd the south, in Abbeville county. 
 
 Upon an expedition undertaken at the instigation of the 
 writer. Prof. S. L. Powell of Newbury, S. C, found at Chester 
 abundant eruptive rocks (granites and diorites), but none of 
 unmistakably volcanic origin. At Lancaster, on the other hand, 
 he found amygdaloids and felsites, showing distinct flow-struct- 
 ures which are certainly of igneous origin and could only have 
 solidified at the surface. 
 
 In Georgia and Alabama nothing can be stated with cer- 
 tainty in regard to ancient volcanic rocks as the crystalline 
 portions of these states have not as yet been petrographically 
 investigated. The porphyry area of Abbeville county, S. C, is 
 probably continued into Georgia. One single specimen of quartz- 
 porphyry showing- a beautiful micropoikilitic structure, collected 
 in northwestern Georgia near the Tennessee line, has already 
 been mentioned by the writer.' A box of specimens kindly sent 
 
 « Report on the Survey of South Carolina for 1856, 2d ed., Columbia, 1858. p. 31. 
 Lieber had the German ideas regarding igneous rocks and their nomenclature. His 
 " trachyte," " domite " and " phonolite " are probably fine grained varieties of the 
 acid volcanic types. 
 
 k 
 
IL 
 
 THE DISTRIBUTION OF ANCIENT VOLCANIC ROCKS. 3 I 
 
 to me for examinativ-ij by Professor Eugene Smith of Alabama, 
 proved to contain nothing which could be identified as ancient 
 volcanic material. 
 
 OENERAL CONCLUSIONS. 
 
 The above rapid survey of the now known and probable areas 
 of ancient volcanic rocks in the crystalline portion of the Appa- 
 lachian system reveals the fact that this cla.ss of material is 
 both abundant and widely distributed. From Newfoundland to 
 Georgia it has been identified. For many areas the evidence of 
 surface or volcanic origin is conclusive, while in many others it 
 Ij as yet only probable. 
 
 The areas of these ancient volcanic ro'cks now known fall 
 roughly in two parallel belts (see map); of these the eastern 
 embraces the exposures of Newfoundland, Cape Breton, Nova 
 Scotia, the Bay of Fundy, Coast of Maine, Boston basin and the 
 central Carolinas ; while the western belt crosses the Eastern 
 Townships and follows the Blue Ridge through southern Penn- 
 sylvania, Maryland, Virginia, North Carolina to Georgia. 
 
 The purpose of the present communication will be accom- 
 plished if it succeeds in directing attention to this group of 
 rocks. New areas should be added ; probable areas investigated ; 
 and known areas monographed all along this old mountain range. 
 How fruitful a field is here spread out to students of geology 
 and petrography may be seen from the results of work in anal- 
 ogous regions by Harker" and Mugge.s 
 
 The identification of truly volcanic rocks in highly or partly 
 crystalline terrains possesses far more than a petrographical sig- 
 nificance, since by fixing what was the surface at the time of 
 their formation, they furnish a certain datum for tracing out the 
 sequence of later geographic changes and geological develop- 
 '"^"*- George Huntington Williams. 
 
 ' Am. Jour, of Science (3d ser.) Vol. 46, p. 47, July, 1893 ; and this Journa!, Vol. t 
 P- 179, 1893. 
 
 'The Bala Volcanic Series of Caernarvonshire, Sedgwick prize essay for 1888 by 
 A. Marker, Cambridge, 1889. ' 
 
 3 Untersuchungen uber die " Lenneporphyre " in Westfalen und den an.?renzendtn 
 GebietenbyO. Mugge. Neues Jahrbuch fUr Min., etc., Beilage Band vui dd czr- 
 721. 1893. • HH 3 5