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In the following notes the writer has tried to give a brief uccount of the geology of this island from notes of his professional work as Inspector of Mines and from other available sources. ^Ir. li. Brown, of the Sydney mines, lived for many years on the island when it was, geologically speaking, an unexplored region. The Transactions of the Society contain several valuable ])a])ers of his, giving many details of the Carboniferous sj'stem. Sir J. W. Dawson, in his 'Acadian Geology,' indicated the outlines of the principal geological divisions, and devoted much attention to the Carboni- ferous Hora. During the past fifteen years Mr. H. Fletcher, of the Canadian Geological Survey, has explored and mapped the island, and the map accompanying these i otes has b(!en reduced from the large scale-plans accompanying his annual reports, from v.hich I have taken several sections. Valuable reports were made by Pro- fessor Lesley, Mr. Lyman, and others on several districts considered of economic importance ; but the list of writers is a scautj' one. The geology of Cape Breton is notable on account of the de^ elop- ment of two great rock series — the Car])oniferous and the Tro- Cambrian. Thi re are no measures known later than the upper portion of the productive Coal-Moasures, and between the basal conglomerate of this period and the Pre-Cainbvian there intervene only a few areas referred to the Devonian and the Lower Silurian. The following formations have been recognized in Cape Breton by the officers of the Geological SuiTey : — Pue-Cambuian (Laurentian) : T , ,. J The Felsite series, iuciucung I .j,,|g c,.j-8talliiie Limestone series. LOWEII SlLlUIAN. j^kvunian. Cakbonu'ekous: ^Middle Coal-foriuation, Millstone Grit, liicluJing^ I G} psil'erous series, I I Limestones, &e. (Lower Coal-1'oruiatioii, PRE-CAMHurAN, Felsii'e Skries. The exact age of the strata included under this term has been a matter of doubt, and many have called them Ijaurentian. Their isolated position has precluded the chance of following them into regions whore convincing .^'tratigraphical relations can be found. The auriferous rocks of the Atlantic coast ot Nova Scotia do not extend into the island, but they supply an important link in the geological se(iuence. They are considered to bo Lower Camljrian, the equivalents of the Longniynd s(?ries, and appcnir with the Acadian series of St. John, New Brunswick, to belong to the gap If) MR. E. (;H,ri\ o:; the geology of bi'twccn the Lower Silurian or Upper Cambrian of Capo Breton, to be alluded to as probable e(iuivalents of the Lower I'otsdani or Linjjula Flags, and the series under consideration. This formation occupies more than one half of the island. North of the Ih'as d'Or lake it stretches in a wide belt to Cape St. Law- rence, interrupted only by the Carboniferous of Margaree Uiver and Lake Aiiislie, and by nai-row fringes of the same strata around the shore and along the valleys of some of the larger s<^reanis rising in the centre of the island. Other large areas are occupied by these strata at Cape ^Mabou, Washabak, Judique, ^[ira, lioisdale, Cox- heath, and St. Anns, Avhere they rise prominent among the low- lying hills and valleys of the Carboniferous. Two divisions have been recognized in these measures. The lower consists of laminated felsites and of interstratitied ])orphyry and syenitic* and gneissoid rocks ; the ui)per is characterized by the addition of great beds of limestone. Mr. Fletcher, speaking of the lower division, gives it as th(^ result of his experience that both tho felsitic and sj'enitic strata are intimately associated as part of the same group of crystalline rocks, differing not so much in compo- sition as in the degree of crystallization they have been subjected to, and that as no evidence has been found proving the higher posi- tion of the felsites, they may at present be considered together. Tho Washabak hills consist of gneiss, mica-schist, syenite, diorite, hornblende rock, quartzite, and felsite ; all are more or less foliated, and sometimes in exceedingly thin laminjo. Tlic Boisdale and ^lira hi'ls arc made \ip chietiy of obscurely bedded syenite, with limited areas of other rocks ; the Coxheatli hills of alternations of syenite, (juartzite, and compact felsite ; and the East Bay hills of felsite, syenite, and granite, in every gradation of colour and texture. In tlie Boisdale hills this series is represented principally by bluish and grey syenite. The syenite contains seams of a serpentinous mineral, and passes frc(juently into granite, quartzite, felsite, and a fine- grained porphyry, with interspaced flakes of hornblende, felspar, and mica. In the districts oi Gabarus and Lnuisberg felsites predominate, and at the former place include beds of felspathic sandstone. Pos- sibly further examination may assign these rocks to a horizon higher than that represented by the East Bay section (to be given below), or thej' may prove to be later than the crystalline limestone series. At Cape Porcupine, on the Strait of Canso, slates occur with coarse syenite, and felsites resembling those of Louisberg and Gabarus. In the Sporting Mountains the felsites occur with red syenite, whereas the Craignish mountains are co^nposed principally of reddish sjenite, overlain by the limestone series. In the northern part of the island the exposures of the great expanse of these rocks present the same general featiiref,. It may be assumed that a more minute and extended study must be devoted to this interesting series of measures before it can be decided what subdivisions, if any, can be determined on. * The term " syenite " is applied by the Canadian Geological Survey to a mixture of quartz, soda or potash felspar, and hornblende. I Q. J. a. S. viil. ilii.| u [To fact p. 52G. dipt St t.,nirfiiif rape North ...^.^ir""""" ATLANTIC OCEAN I Sydney AfintJ ) l^iitori.t Mines 3 Lingiin Mines 4 Briit^ffort Mines J Glace Biiy Minis 6 Reserve Mines J CaleJonia Mines 5 ni.'ck House Mini 9 Gowrie Mini ^^^^.uteriels. <-' Sreton Raihuays IHt**"" Iv V V Pre Cambrian fctsitesH-iS V V do limestones &" Lower Siiurian Devonian fegg Lower Carboniferous S S I Marine Limestoni 1 Millstone Grit . Productive Measures ipm i H ) CAPE nilKTON ISLAND, NOVA HCOTI.V. 517 The ft.llowing sectioi it Irish Cove, V.iiai Buy, inny sorvo to convey a general Idea of the olmracter of these measures, "mid of the asso- ciation of the felsites witli tlio red and grey syenites: — (Irconisli, wliitp, and rwl laminated and granitoid folsito 4S(» (Irt'oiii.sli I't'lsiti" and red .lyoiiilo |0II liliii.-(li Hnfl |M)r|)li_vry ,S,"i I'lirplc and bliiisli iMiniiiatcd Cclsito 2.'».'l Kcil sycuito and rcddisli mdI'i i,'r;init()id rock 1,M7 Ort'cnisli and rcddisli f^raniloid rocks, oi'lon nearly |»uro rcisj)ar I'Ci!) Fi'lsiio and .syenite of viirialile conii)asiliuii, witli voins of t'alcito I.'IO Kod ^^raiiitoid reisitc, vviili dioritc liK) Kimilar all ern;it ions of rod and greenish fclsitos and syenites make up a thickness of ', ,S(MM) Tied and f,'rey syenite, coarse and (ine '2'SM Similar measures, composed of alternations of felsites, .syenites, and aluminous nacreous sliales, greenish and grey in colour, nuike u|) a section not less than H\)M feet in tliicknes.s. At ntuncroiis jioiiits throiigliout the island these raeasurcs are cut by dioritic dykes, some of which are as late as tln^ Lower Ciirho- niferous, but they have not yet been described in any detail. Crystallini; Limestom: Series. Unconforraably resting on these strata, l)nt agreeing with them in their general development and position, is an interesting series of felsites, syenites, dioritcs, niica-scbist, (|uartzite, and (|nartzose con- glomerate, interstratilii'd with crystalline limestone and dolomite. These measures are locally known as the (jleorge's River Limestones of St, Andrew's ChamicL tlie locality in which they are typically develoijcd and were tirst refcr'-od.to their true position. The altenuition of the limes;- nn with the gneissoid atid related rocks brings them into close connection with the felspathic group, from which, however, they are Jipparently separated, owing to the presence of red syenite tuid felsite |)ebbies in the lower conglo- merates and by unconformability. Similarly the Lower Silurian congbjinoriites of St. Andrew's Channel have received witnesses from this limestone series. However conjectural tiny spocidation may be as to tlie age of those measures, it is certain that, as compared with the mctamorpliic slates and ipiartzites of the JiOwer Cambrian auri- ferous strata of Nova Scotia and the fossiliferous Lower Silurian of St. Andrew's Channel, they mark a line ctpuil to that o])sorvablo between the latter and the indurated Devonian and Carboniferous of this island. The area occupied by this limestone series is limilcd in compa- rison with that of the felsite group, but it was formerly, in all pro- bability, of much greater extent, for it presents at several points traces of having suffered severe denudation prior to the deposition of the Lower Silurian strata ; and this is borne out by the thickness of the George liiver s(iotion, viz. 0(502 feet. In the northern district a narrow band stretches between Dundas and Ingonish rivers. Excepting a small patch on Middle liiver, it is not met with again until the head of Whyhogomah Bay ia reached, 5lH MR. T.. OIM'IN ON TIIK OKOLOfiY OK M'hcMce it sfrotclios in ii I»riiie, on Kasl iJay, to St. Andrew's Channel. The foUowinj? soetion from the last-named distriet will Hervc txa an index to its general character in the localities alluded to: — ft. Oninpnot grnnitoid frlnito of many colours 74 lirvy iiiiii ),'ri'('iiifili fVi;il)l(' ^'iiciss 'J'.l llliick and iinilicr-coluurt'd vitreous (jiiiirlzite I !.'> W'liito and Ki'i'y sycnito lit) MiissivK wliilc vitreous quartzitc 400 lUuisii ^;raiiit()i(l rtx'k ,'! Colourless laiiiiimtcd (|uai-tzil(' ami red Hvpuito (\S (Ireeiusli lliiely cryhtalliiie 'lonibleiidc roek 141 lied Hyeiiile H Wliite and bhiisb crystuUino limestone I.T ]{ed sye-iite S (ircenish-gvey ^'raiiitoid felsite lj!> ^Vili!e and bliiisli linie.itone and dolomite K ]{ed sy."iite. lelsile, and porpliyy 7 Limestone, blui.-li and sacelniroidul ](» Eed syenite 2 Wliile limestone and dolomite 378 (Jreenisli iiiie-^rained felsito H7 Greenish pyritons granite and felsito 1 ]2 Granitoid rock 18 Red syenite .'57 Granite, quartaite, and bluish ielsite 473 White, bhiisb, and grey quartz, bluish granite, and icd syenite . 3794 The above, with some concealed intervals, make up a thiekuesa of (;()(»2 feet. These strata resemble in many points the Limestone scries over- lyinj? the syenitic and felsitic group of Newfoundland and New lU-nnswick, iind form the principal nrpument in tavour of rcferrinp; both series to the Jiaurentian. JWineralogictilly there is tilso u resemblance, for in Cape lireton, asbestos, mica, plumbaji-o, tmd bedded iron-ores are frctjuently met among the limestone series, and the discovery of a])atite would render the comparison with the Quebec I.aurcntian limestone complete. Lower Silurian. The area of this formation is limited. Its principal exposure ex- tends along the southern side of the ^fira River for about 30 miles, and hits im avertige width of about 7 miles. A narrow, irregular band stretches from Escasonie, on East liay, nearly to the mouth of the St. (jteorge's River, its width, however, never exceeds one mile. A small patch is also exposed at Shenacadic, on the Little Bras d'Or Lake. The thickness of these measures has not been determined, as thev h; CAIM; IlllKTON ISLAND, NOVA SCOTIA. • 1!» nro <;r('(iny folded unci rcpoatod Ity fiiiiltH. Tlicy nrc diHtitifjuislicd by iiiiincrous licds of coii^lonu'riitc, mid of tine and roarso f^rits, jtlaiiily derived I'loin the I'ro-Ciinihriaii Hlrala. A> numerous jKtints iiro found beds Hlli'd with ppoi'ies of Linifnla, Trilohitep ( Aijnoxtds and (Hums) OiI/iIh, ()/iii/,II(i, tJic., coinpamlile with tin* fossils of iho Lower Potsdam of tho proviiiee of (iiiehee. At several ])oints lher(f are l)eds containing nodules of phosphate of liiiio, rosolvahle under tho microscope into a hitumiiious paste holdinf? siliceous mattiT and fra<;mentH of Llininhi »!;■(•.,— cnprol it es, presunial)ly of some of the larf,'er species of 'riili>hiteH. Mr. Fletcher further draws at toiition to tho };eneral similarity of thoso moasuroH to the |)rimordial rocks of Newfoundland, and to those found hy Mr. Richardson on the Strait of Jlelhisle. 'I'he i'ollowin^ abstract of the section of these rocks, as exposed on Tion^ Island, will show their genurul character in St. Andrew's Channel: — 1. Gri'cniHli-groy, CdiirHC, calcari'oiis cuiftloincratc, pinitiiiiiiin,' nnl syfiiilo, IVlsitt's, 1111(1 ([iiioMzitiM of many colours, intcrsfratitlcil with coiirtu), iiiicact'oiis, hii'iiiiitilic sandMtdiu's, niid blue, piir])lc, and red lulsites. 2. liluirili, ftlaty li'lsitc, with inucli cal(Ni)ar and liii'nmtito. •">. (Iri'cnisli, calcart'iiiiti, |icl)l)ly and slialy sandstones. 4. |)arlv t)ln(', {.'rccnisli, and red I'clsitcs, with pel)!)! ^ and veins of ciilcs|)ap. o. Sca-^ri'((n anil t)lnisli (MMgluniurates, with pebbles o^ I'ldrfilo, culcspar, ([uartzite. and arf;illite. (5. niuisli lelsit(>, vvilli niLicli calcs)wr. 7. IMnisli limestone. H. Ked coniilomerale. y. JUuisli lonestune, fel»ito, and contortod argillite, with voiiis of hii'matito and calcspar. 1<). I51uisli fjnart/oso f;rit, jjassini; into a red congloinerato. 11. Liinestom* and t'elsito alternating in tliin beds. 12. JJluisii-groy felspallii(! sandstone. l.'J. AUernatioiifl of t'elsito limestone, quartzite, niid argillito. 14. Indian red sandy m in, with calcareous sandstone. 15. Uluish i'elsitp, with bens of limestone and quartzito. In tho !Mira Kiver district, on tho Sydney road, arc met jyroenish, })urj)le and reddish, soft, felspathic, micaceous, arenaceous shales and sandstones, quartzite, grit, and conglomerate, with p(d)l)les of lime- stone and greenish argillite. On Kelvin's Jirook are conglomerates containing pebbles of the Pre-Cambrian Measures, succeeded by pur])le, grey, and red ([uartzose and felspathic sandstone and grit, and by Indian red argillites; and on Salmon Kiver aro beds of whitish sandstone, with impressions of Obohlhi, &c., with red sand- stone, marl, conglomerate, etc. It may be remarked that those measures are, as a rule, free from the eruptive rocks which charac- terize the succeeding formation at many points. Dkvonian. These measures occupy an irregular tract, extending from Loch Lomond to St. Peters, and reappear in Isle Madame. They are met with again in that ])art of Guysboro Co., in Nova Scotia proper, lying between Chebucto Pay and the Strait of Canso, and, rccrossing the Strait, extend irregularly from Plaster Cove towards the head waters 520 MR. E. GILPIN ON THE GKOLOGY OF of lliver Inhabitants. The avaihihlo ovidenco points to the Devonian a^'c of these measures, as laid down by Mr. lletcher ; but Sir J. W. Dawson is inclined to refer ])art, at least, to the Silurian. Further search may provide more fossil evidence, a'tliough, as ^Mr. Fletcher remarks, the t ^cks consist generally of shallow-water deposits. The unconforniability between this foruiatiou and the preceding is much more marked than between it and the Carboniferous ; but the unconformable junctions with the latter are strongly marked at Arichat, Lennox Passage, OA\d (juysboro Harbour by degrees of me- taraorphism. included pebbles, and stratigraphical position. The total thickness of the formation has not been ascertained, but the dimensions of various sections would corroborate that of Lennox Passage, where a vertical thickness of 10,000 feet has been measured. The measures, as described by Mr. Fletcher, are arenaceous, argillaceous, and nacreous shales and sandstones, passing into grits of grey, red, and purplish shades, with beds of conglomerate holding quartzite and felsito pebbles. Limestones are met with at several points, and, as at St. Peters, Pirates' Cove, &c., appear to mark an upper he rizon. At numerous localities masses of diorite and trap ore protruded among these measures. This is especially noticeable in the vicinity of St. Peter's Canal. The canal itself is cut in a rock con- sisting essentially of a greenish-grey and bluish mixture of horn- blende and felspars, intersected by veins of quartz and felspar. In the Indian Ileserve, in the same district, the sedimentary rocks are broken through by grey and greenish compact and granular diorite, and pyritous epidotic felsite, traversed by veins of calcspar. At Jerome Point &c. are found exposures of black, greenish, and purplish compact or granular rusty- weathering trap, which is sometimes porphyritic or globuiar. and charged with zeolites, hematite, and chlorite. At several ])oints near St. Peter's and (iuysbcro, impor- tant deposits of specular ore are met with, apparently associated with these eruptive rocks. CARBONIFKROrS. This formation is conspicuously developed in Cape Ereton ; Uiid, apart from the fisheries, to its coal and fertile limestone and gypsum soils arc due what measure of prosperity the island enjoys. Sir J. W. Dawson, in his ' Acadian Geology,' has arranged th ) Carbo- niferous of the Lower Provinces in the following subordinate for- mations : — 1. TJie Upper Coal Formation, containing coal-formation plants, but only thin coal-seams. 2. The Middle or Productive Coal Formation. 3. The Milhtone Grit. 4. The Carboniferous Limestone, with marls, gypsum, &c. 5. The Lotrer Coal-measures, holding some of the middle coal- formation fossils and thin cosd-beds. Some districts do not present all these divisions, the lowest one being frequently wanting or sparingly represented. And in many CAPE BUKTOX ISLAND, NOVA scon A. 521 cases no divisional line can be drawn separatin^ '^ Striita oOC) 2 Carr seam <> •'"» Strata 15)1 <» Barasois seam 1- t) Strata 379 5J David Head seam H Strata 2,'5.") SeainD 3 Stiatx 78 North Head seam 4 Strata 7(> Liugan Main seam 8 Strata 95 '.^ Seam G 2 (> Strata 340 5 SeamH 1 This section does not embrace lower coal-seams of workable di- mensions included in the Millstcno Grit of tho Geological Survey. Shales, arenaceous and argillaceous, with red and green marls, make up one half of the strata. The shales ;)as8 into sandstones, and frequently carry ironstone nodules ; and the more argillaceous beds are crowded with fossils, chiefly ferns. Many trunks of erect ^99 MB. E. GILPIN ON Till: GEOLOGY OF and prostrate Si;/iUarice, with roots attached and growing into the coal, are seen in these shales. Trunks have heen observed nearly five feet in diameter, but they do not usually exceed two feet. The term '* marl " is here applied, not to beds necessarily calcareous, but to red and green shales which crumble on exposure. Sandstone-beds, grey and white in colour, and often fifty feet in thickness, are met at frequent intervals, and nearly always occur a few feet above the coal-beds. Many of the beds are calcareous, and are then flaggy, micaceous, and sometimes ripple-marked. Almost invariably under- clays, highly charged with roots and rootlets, occur under the coal- beds, but in a few cases the coal-seams rest directly on thin beds of fossiliferous limestone, and, in one case, the floor is sandstone. The coal-b(!ds do not merit any particular notice, being similar in many points to those of the Durham coal-field. Millstone Grit. The division-line between this formation and the Productive Measures is entirely an arbitrary one, and, as marked on the Geo- logical Survey maps, is regarded by many as encroaching on mea- sures that may fairly, so far as their coal contents are concerned, be considered productive. This is borne out by the fact that a col- lection of fossil plants, from a point apparently low down in this horizon, about two miles east of Sydney, shows s]wcies, according to Sir J. W. Dawson, occurring only in the Productive Measures, and especially in its higher beds. As coni])ared with the higher division, these strata show a much larger percentage of sandstones, fre(]uently coarse and sometimes felspathic, fewer argillaceous beds, and much fake stratification ; and this formation is specially distinguished from those lying above and below it by the absence of calcareous matter. Near the old syenitic and felsitic rocks the prevailing colour is red ; further away, where the material has been derived from the preceding Car- boniferous horizons, grey shales are met with. The maximum thick- ness in this district is 5700 foot, but it rapidly diminishes towards the north, until at Cape Dauphin only 500 feet are found. Numerous co'il-seams are met, some of workable size and persistent for long distances. The long arm of Millstone Grit, extending up the Salmon and Gasijereau rivers, contains several thin seams of coal, and may represent the formation as developed east of Sydney. The Carboniferous Limestone. In the Sydney district this formation occupies a triangular tract of country between the two arms of Sydney Harbour, and attains a thickness of about 2000 feet. It is composed principally of red and grey shales, sometimes approaching marls in aggregation, argillaceous and calcareous, and frequently carrying nodules of ironstone and limestone. Numerous beds of limestone are met, compact, lami- nated, or concretionary, usually grey and blue in colour, but some- times black and bituminous ; these are frequently associated Avith beds of gypsum and atdiydrite, in some ])arts of the island over CAPK imETOK ISLAND, NOVA SCOTIA. 523 200 feet in thickness. Beds of red and grey sandstone, usually Liminated, often luieuceous and rii)ple-marked, arc freiiuontly met with. The limestones fjenerally contain the fossils characlerizing this horizon, and are frequently charged with galena and co[)i)er pyrites, celestine and manganese ores. The following section, from the 'Geological Survey lleport,' 1875-7(5, p. 407, gives a good idea of the condiiions under which the gypsum and limestone are usually presented : — ft. in. Bhiish-grey cohiinnar limestone l^t) Oi-wii iimrl y Black biliiiiiMious Udilular limestone, mottled greeiiisli auil red compact limestone •••' " Gray, compact, green, and mottled limestone -10 Wliite crurabliag gypsmn ...: l-' Greou gypseous Miarl t) 7 Pink gypsum ^^ t>.* Greenish gypseous marl • 1() Pink gypsum and greenish marl t) (> Bed mieaceous marl with gypsum 7 White gypsum 1 AVhiie gypsum and marl, with veins of gypsum 1 <» Nodular gypsum marl, and limestone 4 The gypsum varies greatly, and tlie following description of an immense' clitf, over one hundred feet in height, on the Bras dX)r Lake, will serve to show its characteristic features. It is essentially white, hut spotted and tinted with many colours. It lies in heds often massive, but frecjuently pointed in every direction. It is usuiilly compact, but often granular, minutely crystalline, or fibrous and radiating. Crystals of selenite, of a brov/uish colour, frcijuently occur in \l ; they are isolated or arranged in radiating groups, and sometimes give the rock a porphyritic appearance. The rock is ho- (juently traversed by veins tilled with fibrous gypsum of various colours, or with large jjlates of transparent selenite. Layers and nodules of anhydrite and of limestone freciuently occur in the beds or divide them' Long-continued weathering roughens the surface of the gypsum, owing to the presence of silica as sand. Glauber's salt, common salt, and carbonates of magnesia and calcium, sidphur, and several varieties of silico-borate minerals are not uncommon. Lower Coal-Meastjres. (Lower Carboniferous Conr/Iomerate.) This, the lowest member of the Carboniferous division, cor- respomiing with the Bonaventure formation of Gaspe, and the basal conglomerate of New Brunswick and ISTcwfoundland, ^j of variable volume, and cannot in this district be separated by any strict line from the overlying limestone formation ; and it is the opinion of Mr. Fletcher that,' in the districts surrounding the Bras d'Or Lake, much of it may be considered contemporaneous with the Limestone series. In the Sydney district, near the Coxheath Hills, it haa a thick- ness of 2525 feet, which rapidly diminishes as its strike is followed 624 MR. E. GILPIN ON THE GEOLOGI OP to the north and south. This formation generally presents the aspect of a friable, reddish conglomerate, the pebbles varying in size up to a diameter of three feet. The masses are frequently of little coherence ; in some casos the matrix is calcspar, haematite, or quartz. The conglomerates, the distinguishing feature of the formation, alternate with beds and masses of red and grey, coarse- and fine- grained, friable sandstones, and with beds of red and green marl and an occasional bed of limestone. Usually the upper beds are finer than those at the base, but many sections are largely made up of conglomerates. Passing to the westward we meet the Carboniferous of St. Peter's Bay and the lliver Inhabitants. The marine limestone and some representatives of the division just alluded to border St. Peter's Bay and inlet and the northern shore of Isle Madame, and, passing under the higher divisions, skirt the Sporting Mountains, and passing round the head of West Bay, fill the valley of the Eiver Inhabitants, and are exposed on the shore of the Strait of Canso at Plaster Cove. In this group are included measures which resemble more closely the typical Lower Coal-formation of Sir J. W. Dawson's 'Acadian Geology ' than any met elsewhere in the island, and the tint on the map really includes both the marine limestone and the lowest division. These measures pass into the River Denny's basin and extend to the Grand Narrows. The officers of the Canadian Geological Survey have grouped the Carboniferous measures overlying these subdivisions under the term " Middle " Carboniferous, including the Millstone Grit, Productive Measures, and beds referred with doubt to the Upper Coal-forma- tion, as the dividing lines are obscure and the structure not yet fully worked out. On the map the Middle Coal-formation districts, as indicated by coal-crops, are marked by their appropriate tint, and the remainder of the debatable ground is referred to the Millstone Grit. Mr. Fletcher gives the total thickness of the Carboniferous strata at 21,960 feet, which probably embraces all the subdivisions already described in the Sydney district ; and, possibly, the 1350 feet of measures referred to by him as overlying the Little-River coal- series (8926 feet thick) may represent part of the Upper Coal-for- mation, subdivision No. 1 of Sir J. W. Dawson. The measures do not present many points of interest calling for special mention. It may be remarked that the coal-beds and their extent are imper- fectly known, and that they are not considered so valuable as those met elsewhere in the island. Some of the sandstones and shales of the River Inhabitants are little more than compact sand and mud, while at other points the rocks have the normal hardness of the Carboniferous strata. In describing the Carboniferous strata lying north of a line drawn from Baddeck through Whyhogomah Bay to Low Point, Mr. Fletcher has adopted the following classification : — r b f -o /Middle: Millstone Grit and Middle Coal-formation, ■' ' \ Lower : Conglomerate and Marine Limestone ; but I have followed the regular classification on the map. CAPE BRETON ISLAND, NOVA SCOTIA. 625 The Coal-measures now form patciies of whnt was, in all pro- bability at one time, a continuous outcrop fror^ Judique to Cheti- camp. These strata resemble those described in the Sydney district, and contain numerous beds of coal of excellent quality, which, how- ever, have not yet been worked. The Port Hood coals, in their high contents of water, from 3 to 7 per cent., resemble lignite coals, but in all other respects are excellent bituminous coals. The Millstone Grit of this district appears to be limited in extent, and may be re- presented by bome of the strata underlying the coal-beds of Port Hood. The line between these strata and the Marine Limestone is sharnly marked by unconformability and the change in the condition^ of deposition. The general characteristics of this subdivision are similar to those already noted, and its distribution may be learned from the map. Underlying the Limestone series are numerous wide-spread areas of grits, coarse sandstones, and conglomerates, with argillaceous shales and a few beds of limestone. At Judique, Mabou, Broad Cove, Forest Glen, Grand Etang, and Chcticamp these Measures are greatly altered by the intrusion of igneous rocks. In the Judique district these intrusive masses vary greatly in texture, colour, and composition, but are essentially dark, massive, granular, and com- pact, chloritic, dioritic, and felsitic rocks. At many places little change has been produced in the sedimentary rocks at the point of contact, but frequently the metamorphism has been so great that no line of contact can be observed, ^t otlier points these strata are comparatively unaltered, and at Hunter's Mountain, Whyhogomah, and Lake Ainslie they hold bituminous shales with impure coal- beds, show signs of petroleum, and resemble the Lower Coal-Mea- sures of Plaster Cove. Superficial Geology. The superficial geology of Cape Breton does not present many points of interest. There are, I believe, no moraines to mark glacial action. The earth-covering varies according to the age and nature of the underlying strata. The Pre-Cambrian rocks are fre- quently almost bare, and their rugged and steep hill-sides afford soil only for the growth of timber ; and rains following forest-fires have frequently denuded large tracts of almost every trace of earth. The more level tracts of the Pre-Cambrian, Silurian, and Devonian measures are diversified by numerous lakes, with slow streams and swamps. The soil is usually thin, clayey, or sandy, with boulders of the subjacent rocks. In the brooks and intervals sands and gravels are met with of recent derivation from the adjacent hills. In the Carboniferous districts the soils are deeper and often of great fertility. The erratic boulders found over these measures are derived from the neighbouring subdivisions of the felsitic and syenitic series, and have seldom travelled far. In several localities peat and carbonized tree-trunks have been found under these clays, with remains apparently of Mastodon r/igantei(s (?). There is a total 526 ON THE GEOLOGY OF CAPE BRETON ISLAND. absence in Cape Breton of the fossiliferous marine clay characterizing the rost-Plioceno days of the Lower St. Lawrence, and this may be duo to rapid elevation of the land. At present it is thoii-ht by some that a slow subsidence is taking place. The Carboniferous measures of the Sydney district have sufFered greatly by the action of the ocean, which is rapidly wearing them away. At some points, according to Mr. ]l. Brown, the shore recedes at an aveidge rate of live inches per annum. This waste of the softer measures has furnished material for the sand-beaches which are numerous around the Bras d'Or Lake and along the south coast of the island. The older rocks are often rounded, but seldom show stria). Around Sydney Harbour and to the east and south of Sydney the striic are observed chiefly on the :Millstone Grit, and vary between S. 45^ W. and S. 78" W. magnetic. Similar courses are met with at East Bay, Gabarus Bay, Framboise, and other points on the south shore. It is perhaps probable that the courses of the compact ridges of the I're-Cambrian strata have determined much of the denudation, and that the Bras d'Or Lake and the principal river-valleys owe their form to the cutting-out of the softer shales and sandstones, which are now frequently presented as fringing the harder and older measures. Some of the lakes present interesting marks of the action of ice. The winter's ice, when melted around the shores of the lakes and moved by the wind, frequently drives large boulders for yards before it ; these leave long furrows in the mud, and remain, wdth a mass of small stones and earth, in front of them. In other cases, lakes are in this manner surrounded by dyke-like walls of stones and earth. ictcrizing this may ht by lOU D RufFored •injj: tliem tho shore s waste of fl-boaches alon^ the 111 (led, but ) east and tone Grit, Similar and other > 1 ■ ; ridi2;e.s of eniidation, illeys owe andstones, ardor and ion of ice. lakes and for yards nain, with ther cases, i of stones I I , \ Q. J. G. 8. vol. xlii.] 4 [To face i\ 52G. Citff St l.a:vrin(f Caftt^'orlh tBi^' •mcf I SyiiHi-y .l/iii,T I I^Morii Mines 3 Lingtin Mittci 4 Briiiofort ,\fiius 5 Glttcf Bay Mint! 6 Rtstrvi Mints 7 CaMi)iiitt Mines S /Uo(k House Mi Lo7uer Silurian V ••■.■•. • :':•.■;■:;.■ Devonian t^»~^ I-ovier Carboniferous f MiUstont Grit » I Productive Measures