Chapter XIX: Appendix (3)

The extent to the westward of the limestone deposit of Lake Winipeg is not well known to me; but I have traced it as far up the Saskatchewan as Carlton House, and its breadth there is at least two hundred and eighty miles. For about one hundred miles below Carlton House, the river Saskatchewan flows betwixt banks from one to two hundred feet in height, consisting of clay or sand, and the beds of limestone are exposed in very few places. The plains in the neighbourhood of Carlton abound in small lakes, some of which are salt. The country which the Saskatchewan waters for one hundred and ninety miles before it enters Lake Winipeg, is of a different kind. It is still more flat than that about Carlton, and is so little raised above the level of the river, that in the spring-floods the whole is inundated, and in several places the river sends off branches which reunite with it after a course of many miles. In this quarter the soil is generally thin, and the limestone strata are almost every where extensively exposed. To the southward of Cumberland House, the Basquiau Hill has considerable elevation. I had not an opportunity of visiting it; but in the flat limestone strata, near its foot, there are salt springs, from which the Indians sometimes procure a considerable quantity of salt by boiling; and there are several sulphureous springs within the formation.

I observed no beds of conglomerate in it, and no sandstone associated with it; but the extensive plains which lie betwixt Carlton House and the Rocky Mountains are sandy, and beds of sandstone are said to be visible in some of the ravines.

The line of contact of the limestone with the primitive rocks of Lake Winipeg, is covered with water; but at the Dog's-Head, and near the north end of Beaver Lake, they are exposed within less than a mile of each other. To the southward of the Dog's-Head in Lake Winipeg, and in a few other quarters, some schistose rocks, belonging to the transition series, are interposed between the two formations.

Before quitting the formations of Lake Winipeg, I may remark, that the height of that lake above the sea is perhaps equal to that of Lake Superior, which is eight hundred feet.

LIMESTONE OF THE ELK AND SLAVE RIVERS.

The next formation I have to mention is one which appears to possess most of the characters ascribed by German geologists to the zechstein. It extends from the north side of the Methy carrying-place down the Clearwater, Elk, and Slave Rivers, and along the south shore of Great Slave Lake to the efflux of the Mackenzie. The line I have traced was the route of the expedition, and is also very nearly that of the eastern boundary of the limestone. Primitive rocks occur in Lake Mammawee, Athabasca Lake, and on the Stony River; and on several parts of the Slave River they are separated from the limestone only by the breadth of the stream. On Great Slave Lake, the Stony Island, on the north-east side of the mouth of Slave River, is composed of granite, whilst the limestone strata are exposed at Fort Resolution on the south-west side.

[Sidenote: 1027, 1028] The limestone in this extensive tract is commonly in thin and nearly horizontal beds, and much of it exactly resembles in mineralogical characters the dolomite and chert of Lake Winipeg. It is interstratified with thin beds of soft white marl; and in a few places with a marly sandstone. Extensive beds of stinkstone also occur, and many beds of limestone containing fluid bitumen in cavities. The bitumen is in such quantity, in some quarters, as to flow in streams from fissures in the rock; and in an extensive district, around Pierre au Calumet on the Elk River, slaggy mineral pitch fills the crevices in the soil, and may be collected in large quantities by digging a well.

A calcareous breccia also exists in various places, particularly on the Slave River. Springs depositing from their waters sulphur, and sulphate of lime, slightly mixed with sulphate of magnesia, muriate of soda, and iron, are common and copious. A few miles to the westward of the Slave River, there is a ridge of hills several miles long, and about two hundred feet high, having several beds of compact, grayish gypsum exposed on its sides. From the base of this hill there issue seven or eight very copious, and many smaller springs, whose waters deposit a great quantity of very fine muriate of soda by spontaneous evaporation. The collected rivulets from these springs form a stream which is, at its junction with the Slave River, sixty yards wide and eight or ten feet deep.

[Sidenote: 1020 to 1026] The organic remains, in this deposit, according a list kindly furnished by Mr. Sowerby, consist of _spirifers_, [Sidenote: 1029 to 1032] one of which is the _spirifer acuta_; several new _terebratulae_, of which one resembles the _T. resupinata_, a _cirrus_, some crinoidal remains, and corals.

At the union of Clearwater and Elk Rivers, the limestone beds are covered to the depth of one hundred and fifty feet with bituminous shale.

I have stated, that on Slave River this limestone formation succeeds immediately to primitive rocks, but I am not acquainted with the rocks that lie to the eastward of it on the Elk River. The traders report that there are extensive deposits of sandstone on the eastern arm of the Athabasca Lake, and, perhaps, these sandstones extend nearly to Clearwater River. Sand covers the limestone on that river to the depth of eight or nine hundred feet, and the fragments of sandstone in it are large, numerous, and not worn.

The quantity of gypsum in immediate connection with extremely copious and rich salt springs, and the great abundance of petroleum in this formation, together with the arenacious, soft, marly, and brecciated beds interstratified with the dolomite, and above all, the circumstance of the latter being by far the most common and extensive rock in the deposit, led me to think that the limestone of the Elk and Slave Rivers was equivalent to the zechstein of the continental geologists. My opinion, however, on this subject is, from a total want of practical acquaintance with the European rock formations, of little weight; and several eminent geologists are, after an examination of the organic remains and mineralogical characters of the specimens brought home, inclined to consider the formation as analogous to the carboniferous or mountain-limestone of England.

As to the limestone formation of Lake Winipeg, I have no doubt of its identity with that occurring in the islands at the passage of La Cloche, in Lake Huron, and also with that at Cape Parry and at Cape Krusenstern, on the coast of the Arctic Sea. It is probable, also, that these four deposits belong to the same epoch with the limestone of Elk and Slave Rivers, although they differ in containing little or no petroleum. It is proper to mention, however adverse it may be to the opinion I have ventured to hint at above, of these extensive horizontal deposits of limestone being referable to the zechstein, that the limestone of Lake Huron is generally considered as belonging to the mountain-limestone; and Professor Jameson, from a review of the organic remains occurring in the Lake Winipeg deposit, considered that it also belonged to that formation. The formation of Cape Lyon may be, with less danger of a mistake, referred to the transition or mountain-limestone.

THE END.

FOOTNOTES:

[20] This was estimated by allowing one foot descent per mile for Bear Lake River, whose length is seventy miles; and three inches per mile for the descent of Mackenzie River, from the junction of the former river to the sea, being a distance of five hundred miles.

[21] In our former journey, we sounded near the Rein-Deer Islands in Slave Lake, with sixty-five fathoms line, without reaching the bottom.

[22] Section of the cliffs at Limestone Point--strata dipping to the N.N.W.

In the section the strata are represented much more inclined than they really are.

231 Fine-grained, nearly compact, yellowish-gray dolomite, forming the summit of the hill, but the first, or lowest stratum, in the language of geologists.

232 Compact, splintery dolomite, with a conchoidal fracture, and wax-yellow colour--second stratum.

233 A cherty dolomite; containing calc-spar--third stratum.

234 Bluish-gray dolomite, traversed by calc-spar--is nearly compact, and has an uneven, splintery fracture--forms the uppermost portion of the fourth stratum.

235 Talcose? limestone, having a curved slaty structure, and containing cherty portions--from the lower part of the fourth stratum.

236, 237 Earthy greenstone? forms the fifth stratum.

238 Brownish-red dolomite, with an uneven fracture; scarcely splintery. It has a compact structure, and is intersected by veins of calc-spar--from the sixth stratum.

239 Light yellowish gray dolomite, passing into chert--seventh stratum.

240, 241 Thin slaty beds of brownish-red dolomite, like 238--eighth stratum.

242 Bluish-white porcelain chert, sometimes mixed with red dolomite--243--ninth stratum.

[23] _List of boulders gathered on the beach at Fort Franklin._

261 Coarse crystalline granite; felspar flesh-red in large crystals; quartz gray; mica black.

262 Granite; felspar paler, and less distinctly crystallized; quartz in small quantity, gray; mica blackish, and rather abundant.

263 Granite; felspar partly reddish, partly yellowish-white, quartz in small grains; mica equalling the quartz in quantity, black.

264 Granite, fine-grained: quartz and felspar, white, the former nearly transparent, black mica in small specks, garnets.

265, 268 Granite; quartz in regular crystals; mica blackish, in small quantity.

266 Granite? red felspar in large crystals; quartz gray; mica replaced by chlorite?

267 Granite; felspar gray; chlorite? in small quantity.

269 Granite, small grained, passing into gneiss; reddish-brown felspar and gray quartz, intimately mixed, and having in the aggregate, a vitreous lustre; mica in layers.

270 Granite coarser grained than the preceding, containing more quartz; the mica disseminated.

271, 273 Granite with little mica, some portions of the felspar tinged green.

272, 274, 275, 277, 278, 279, 280, Granite grayish and small grained mica black.

276 Granite; brick-red felspar; quartz; and augite?--no mica.

The mica is mostly black in all the granite boulders that occur here, the felspar most frequently reddish.

281 Porphyritic granite? felspar imperfectly crystallized, containing large, imbedded crystals; quartz; and chlorite?

282 Granite? composed of felspar, of quartz, with, perhaps, a few minute grains of chlorite?

283 Granite? contains little quartz, and a few scales of mica, with some chlorite?

284 Sienite; felspar somewhat granular, a little quartz and chlorite?

285 Porphyritic sienite? having a basis of slightly granular felspar, with light-coloured crystals of felspar, some quartz and disseminated grains of chlorite?

286 Reddish-brown hornstone porphyry.

287 Crystalline greenstone.

288 Fine-grained greenstone.

289 Porphyritic greenstone.

290 Pitchstone porphyry.

291 Greenstone slate with pyrites.

292 Amygdaloidal claystone porphyry.

293 Compact grayish-blue dolomite.

294 Splintery dolomite.

295 Cellular dolomite.

296 Swinestone.

297 Limestone with corallines.

298 Chert.

299 White quartz.

300 Quartz-rock.

301 Coarse sandstone.

302 Fine-grained white sandstone.

303 Fine-grained red sandstone.

304 Fine-grained striped sandstone.

305 Fine-grained spotted sandstone.

306 Slaty sandstone verging towards slate-clay.

307 Dark-red claystone.

308 Light-coloured claystone.

[24] _List of Specimens from Diluvial Gravel, Fort Franklin._

1 Amphibolic granite, rather coarse crystalline, felspar flesh-red.

2 Ditto, approaching to gneiss.

3 Gneiss approaching to mica-slate, felspar white, and in small quantity.

4 Greenstone with much felspar and minute disseminated pyrites.

5 Quartz rock? having brownish and imperfect crystals, and a reddish disintegrated mineral disseminated.

6 Brownish-red and fine granular quartz-rock, with a somewhat splintery fracture. It has the aspect of compact felspar.

7 Quartz rock, reddish crystalline texture, and vitreous lustre, but with small rounded grains imbedded in it, bringing it near to sandstone.

8 Coarse sandstone; rounded grains of quartz united by a clayey basis.

9 Fine-grained purplish sandstone, with grayish spots. This sandstone occurs _in situ_ near the Copper Mountains, between Dease Bay and the Coppermine River.

10 Fine-grained yellowish-white sandstone.

11 Yellowish-gray sandstone, composed of small rounded grains of quartz united by a powdery white basis.

12 Yellowish-gray sandstone, composed of fine grains of vitreous quartz.

13 Sandstone, having different shades of brownish-red colour, in layers.

14 Lydian stone.

[25] Mr. Sowerby, who inspected all the specimens containing organic remains, says of this species of ammonite, "it is, as far as I can discover, new. It contains sulphate of barytes, and is probably referrible to some of the Oolites near the Oxford clay." Although it was found lying on the beach, I have no doubt of its having fallen from some of the beds of clayey sandstone, which form the walls of the rapid.

[26] 33 This limestone appears as if composed of an aggregate of small crystals, and presents many drusy cavities.

34 Is an adjoining bed of a similar colour, of a fine crystalline texture, but without the drusy cavities. It appears to be a dolomite. These two beds dip to the northward.

35, 36 Calcareous breccia. The two preceding beds (33 and 34) were from the summit of the portion of the hill which forms the cliff, but taken a little farther to the N.W. In the cliff the beds dip, as has been stated, to the S.W. The following beds occur in going to the north-westward, towards the summit of the highest peak, commencing near its base, in a valley behind the cliff.

37 A fine-grained blackish-gray dolomite, having interspersed many nodules of chert, or grayish-white quartz, not crystallized.

38 A very compact, opaque limestone, of a smoke-gray colour, having a flat and slightly splintery fracture. Effervesces briskly.

39 Blackish-gray rather compact limestone, having a flat and dull fracture, and intersected by small veins of calc-spar. This is a prevalent stone in the hill, and also occurs in quantity in other limestone ridges in the neighbourhood.

40 An ash-gray, fine-granular dolomite.

41 A conglomerate, forming the summit of the highest peak.

[27] 57 This breccia has a white calcareous basis, which incloses angular fragments of compact, yellowish-gray limestone, with smooth dull surfaces.

58 Grayish-white limestone, having a fine crystalline texture, with drusy cavities, incrusted with bitumen.

59 Limestone, apparently composed of crystalline fragments, highly charged with bitumen, cemented by a whitish carbonate of lime in minute crystals. I could not satisfy myself whether this variety of colour proceeded from partial impregnations of bitumen, or from a brecciated structure. Specimens 58 and 59 were from beds near the western part of the hill.

60 A fine-grained dolomite, approaching to compact, having a flat and somewhat splintery fracture, and a brownish-gray colour.

61, 62 Limestone in the body of the hill, resembling No. 39 in the hill at the rapid in Bear Lake River, but with larger veins of calc-spar.

63, 64 Dark blackish-brown bituminous shale, veined with calc-spar, and passing into bituminous marl-slate. It contains nodules of iron pyrites.

65 Thin bed of indurated shale, approaching to flinty-slate, lying at the foot of some beds of bituminous limestone. Their connection not clearly made out.

66, 67, 68 Bluish-gray, fine-grained sandstone, some of them passing into slate-clay, and scarcely to be distinguished from those at the rapid in Bear Lake River. Capt. Franklin took these specimens from horizontal beds at the foot of the hill facing Bear Lake River.

[28] Sir Alexander Mackenzie, in p. 95 of his Voyage to the Arctic Sea, states, that he saw several small mineral springs running from the foot of this mountain, and found lumps of iron ore on the beach.

[29] Travels in the Arkansa, p. 52-54.

[30] Section I.

The section of the bank at the mouth of the Bear Lake River
is as follows, beginning with the lowest bed:--

81 Gravel, with thin layers of sand rising from the water's
edge in a perpendicular cliff, to the height of 30 feet
Lignite (70 to 80 and 84) 1
83 Potter's clay of a bluish gray colour, alternating
with layers of sand 40
A sloping uneven brow, covered with soil, extends
to the summit of the bank 20
----
91

Lydian stone is the most abundant, and whitish quartz the least so of the pebbles mentioned in the text as entering into the composition of the gravel.

[Sidenote: 82] A little farther up the Mackenzie, this bed of gravel passes into sand, which, in some spots, has sufficient coherence to merit for it the name of sandstone. During a great part even of the summer season, all the beds of sand are frozen into a hard sandstone; but a piece having been broken off and put into the pocket, speedily thawed into sand.

[Sidenote: 83] Specimens of the clay, which I have denominated potter's clay, taken from near the beds of lignite, have a colour intermediate between yellowish-gray and clove-brown, a dull earthy fracture, and a slightly greasy feel. It is not gritty under the knife, and acquires a slightly shining smooth surface, adheres slightly to the tongue, and, when moistened with water, assumes a darker colour, and becomes plastic.