IMAGE EVALUATION TEST TARGET (MT-3) / J/ V V / o signifie "A SUIVRE", le symbole V signifie "FIN". Maps, plates charts, etc., may be filmed at different reduction ratios. Those too large to be entirely included in one exposure are filmed beginning in the upper left hand corner, left to right and top to bottom, as many frames as required. The following diagrams illustrate the method: Les cartes, planches, tableaux, etc., peuvent dtre film6s A des taux de reduction diffdrents. Lorsque le document est trop grand pour dtre reproduit en un &aul cliche, il est film6 d partir de Tangle sup6rieur gauche, de {nauche k droite, et de haut en bas, en prenant le nombre d'images ndcessaire. Les diagrammes suivants illustrent la mdthode. 1 2 3 1 2 3 4 5 6 PLATE m . t' diBaaquel. 'iehaujePt THE D EVONI AN CAPE BRETON, N.5. PROM SURVKYB B>r H. FlCTKHIR, CANADIAN sea. »URVKY. Scale to S milts to an inch. CARBaHIFEROUS V.'.OV.XVAW Laukentian J&>>I\*>>>>jC nitniOrae Sim»m Urh.C'VSlJa/m l^H^invt. Trans. N.S.Inst. Nat. Sci.. Vol. VII, Part 4 .'.'; ^ /■j*-* / C-^ V) PLATE m . Cape Kei G*»rg»^ ..^ irrr:- -I, aaque I. ,^' RedH^ THE D EVONI AN t->rT^ ow ' CAPE BRETON, N.5. FROM SuRVKYi my H. Flctkhkr, CAMADIAN sea. aURVKY. Sc ' to 5 miUs to an ine h . ^PeUtdeqrat Inlei Devonian ■^:i-}^mimim LBiL0iii.Jm. Mmttima Htm mm IMt.CHSiJahix Ht tail flu. iTifniintrtiom of the Nova Scoiimi Imtitutc of Natunil Srieme, Vol. T//., Part 4, (ISS'J-'.m.) IT. VII.— The Devonian of (Jape Bueton. By E. Gilpin, Jr., a. M., F. G. S, Inspector of Mines. (Head Uth A/n-il, 1890.) In my last paper on the Geology of this Island, I described njirHM'als of the Carbonifeious Division, and have now to ch iipoji the horizon next in descending order. The exact lliinitation of this horizon palccontologically speaking may yet among the unsettled prol)lems, and the knowledge so far rned of its relations in Cape Breton may perhaps be summed l»y saying that it carries back a step the conditions so widely ivailin^^ here at the opening of the Carboniferous. No dis- ctive harvest of tl)e flora permits tlie correllation of its divi- ns It may however be a.sserted that the position is of more portance than the name, and that here it fills a gap, more or s completely, between the Silurian and Carboniferous. As posed here it is a formation not of special interest from a ©logical or mineralogical point of view, and at present the most cresting field for study offered by it are the numerous dykes d their metamorphic powers. Geo;,'raphically speaking it begins at Loch Lomond, near the nnty line, and runs toward MacNab's Cove, having a selvage Carboniferous between it and the Pre- Cambrian felsites of st Bay. From MacNab's Cove it runs to St. Peter's, shewing elf at the head of the various coves and indentations, the ands and points of land being covered by the Carboniferous, om St. Peter's it fills the shore eastward as far as Lower Ardoise, where it meets the Pre-Cambrian, and skirting these easures runs north-easterly to the Grand River which it Hows to the place of commencement. Several outliers of are met on the east bank of the river, resting on the tel- es which occupy almost all the shore as far east as 3K2 THK DEVONIAN OF TAPE HHKTON— OILPIN. Mira Hay. All IsIh Madame (Arichat Island) is occupied by it, except a narrow fringe of carboniferous extending from Gran dique westward ly along the north shore, and a few patches of felsites, etc. near Arichat town and Petit do Qras Harbor. It is met again on the Guysboro' shore, and extends nearly to the mouth of the Strait of Canso where it crosses into Cape Breton again. Here it sttetches along the shore from Port Hastings to Low Point, and extends inland about six miles, among the spurs of the band of crystalline limestones, gneisses, etc., which is best known by its exposure at Whycocomah. From this it will he seen that the extent of these measures in Cape Breton is limited, and that they do not form mining or agricultural dis- tricts. They are most particularly presented to the traveller passing through Lennox Passage, where he sees the low, mon- otonous, spruce-covered hills of Arichat Island, broken by few clearings and animated only by the huts and stages of the fishermen. In the district lying e ist of St. Peter's, the presence of great masses of igneous rocks, has permitted of bolder outlines, and the Devoninn is presented in rolling hills, with narrow irregular valleys. Prior to the surveys made by Mr. Fletcher, of the Geo- logical Surve}, these measures were generally referred, without much comment, to the lower Carboniferous. In reporting on the field work of 1877, he says of the two basins of metamorphic rock running parallel to the great felsite series, that the fiist, stretching from Mira River to Upper Marie Jo.seph, is character- ized by primordial fossils. The second, probably Devonian, is characterized by more recent shells end plants. It contains mu.sses of j^ranitoid and trappenn rock, and the associated strata bear a elos(( lithological resemblance to the Cordaite shales and DadoxyloPi sandstones of St. John, New Brunswick. These .strata, in the St. Peter's district, present numerous out- crops, but are .so contorted that no continuous section can be give-^ • 'lor can any reliable estimate be formed of their thickness. The various sections are compo.sed chiefly of coherent grits, sandiif nes, areno-argillav^eous shales, .sometimes quartzo-felspa- thic, greenish, blueish, reddish, purple, gray or whitish. Car- •vt I t. .1 ^. V \ (I •i' V / * '(t * ♦ '<• ■J •ft i l> .' it '.,i .V I ,ii ,> THE DEVONIAN OF CAPE BRETON — GILPIN. 883 bonized plants, cordaites, terns, calaniites, and sphenophyllum are met. Argillites of varying degrees of hardness are found, with green, black, and red colors, and are frequently nacreou^. The conglomerates are red and greenish, and compact; the peb- bles being quartzite, with sandstone and felaite, and they are frequently banded with sandstone. Limestones are met at many points and they ditt'er from those of the carboniferous, in being in all cases highly altered, in places approaching marble in texture. The limestone seen at many points between St. Poter's and Macnab's cove is bluish nnd grey, compact, cry.'-talline, concretionary or slatey. Galena is some- times observed in it, and layers of chloritic matter. At Robert- son's cove the limestone contains conularia, atrephtorynchus, and stems of plants and other organic forms. It contains veins and nests of crystalline spar, hematite, etc. Another limetone near MacNab's cove is described as blackish, bluish, grey, yellow weathering, dressed with hematite, veined with calcspar, with cone in cone concretions, and holding dark purple fluorspar. In the northern part of the district these measures are rather more compact and altered than near the shore. At numerous points they have their joints tilled with calcspar. These mea- sures are cut by numerous masses and ridges of trap and diorite. The St. Peter's Canal is excavated in a mass of greenish, grey and yellow mixtures of hornblende and felspar, etc. Dykes of coarse greenish diorite are met, slightly altering in their immedi- ate vicinity the sandstones and grits they intersect. Black, bluish and greenish trap passing into felsite or diorite occurs at Alex Island. Its caviiies contain hematite, calcspar, chlorite and zeolites. These strata cut off by the sea emerge again, and as already noted, occupy nearly all the island of Arichat. Mr. Fletcher, during the seasons of 1878 and 1879, continued the work of tracing the geological formations of Richmond and Inverness Counties. He, however, raises a question if part of the beds on this Island may not be older, and reteis to the opinion of Sir William Dawson, who is inclined, on specimens of a species of Rh} nchouella found by him at Rocky Bay, near Arichat, to 384 THE DEVONIAN OF CAPE HIIETON— GILPIN. refer some of the 8trata to the Silurian, on the analogy of other parts of Nova Scotia. To clear up these questions, which are more easily asked than answered, a much more detailed survey and study would be required. Good examples of the unconformability between the Carbon- iferous and Devonian are met here, where the former, little altered, come into contact with and hold pebbles of the uieta- morphic rocks. Between Rocky Bay and Lennox Passage there seems to be a vertical thickness of 10,000 feet of strata. In general character the rocks of this district resemble those of the same formation, as exposed about Loch Lomond and Grand River. Mr. Fletcher appears, upon more mature reflection, to question if the limestones of St. Peter's may not be at the base of the CarboniferouH, and that their alteration by the igneous rocks of the locality mark the Carboniferous date of the meta- morphic action. I do not myself recognize much resemblance between any of the St. Peter's diorites, etc., and undoubted Car- boniferous dykes whirh I have seen elsewhere. However this may be viewed, the limestone, whether placed at the top of one formation or at the bottom of the succeeding one, may be looked upon as marking a period of change, with differences in level, and the consequent change in nature of sediments. Over large parts of Arichat Island are beds of quartzite and sandstone, with reddish and purplish conglomerates, giving a rocky, rough surface, barren, and intersected by swamps. Petit de Gras Island is largely made up of conglomerates. At Rocky Bay coherent grit and fine conglomerate, with their irregular veins of quaitz, are succeeded by purple, greenish, and gray grits, Indian red, gray, flaggy, arinaceous, cleft and jointed rocks, sonjetimes friable, and pearly with quartz in fi'ms, blotches and veins con- taining much chlorite. The different varieties seem to be con- fusedly mixed, the sandstone passing on one hand into fine granu- lar quartzite.and on the other into compact sandstone, often almost replaced in the bedding and across it by veins of quartz and calcspar. The abundance of calcspai* in all the rocks on the island is noteworthy, but I am not aware that it carries any notable amounts of metallic sulphides, etc. Fossil plants are • ', '> \ /' Si ^ 'i' I s ^v K i 4 K i ^ • ', r^ \ /" THE DEVONIAN OF CAPE BRETON— GILPIN. 385 f r€(|uently founJ. The general trend of the measures appears to run lengthwise through the island and to connect naturally with the St. Peter's and the Guysboro' districts. The exposures of diorite, etc., are not as prominent a feature here as in the former district, but examples can be noticed where the dykes cut the beds and pass laterally between them, with comparatively local amounts of metaraorphism. Passing to the thiid area of Devonian rocks, we find them e'xpo.sed beneath the limentone of Plaster Cove. They consist of ' «» ' gieenish quartz, felspathic sand-stones, associated with dark \ greenish, veined, very coherent shale and sandstone, conglome- rate, and black shales. On the Victoria Road, a mile and a half from Hastings, are whitish coherent grit, and conglomerate, with many veins of quartz. Some of the exposures of grit and shale