hard when barriers of ice, during the high spring floods, often raise the river thirty feet above its ordinary level. Then the frozen earth resists the action of the water as a rock would do, and the surface yields only in proportion as it thaws, which is slowly, since the water loaded with ice is kept down to the freezing point.

I observed that the bank of the river was generally higher than the land behind it, by at least the thickness of the diluvial capping, and sometimes by a part of the sand or clay of the tertiary beds, and that the narrow elevated bank extended in the same form along the principal affluents, a marked instance of which occurs on the south side of Great Bear River. In consequence of this configuration of the surface, the spring floods of melting snow accumulate, and at length make their escape through gullies, contributing further to the ruin of the bank, and giving it a broken and hilly outline when seen from the river. Landslips are of common occurrence, and are occasioned by pressure of water collecting in fissures produced by the partial subsidence of the cliff.*

Similar tertiary coal formations occur on the flanks of the Rocky Mountains; the most southerly one of which I have any account, being in the Raton Pass, in latitude 37° 15′ N., longitude 104° 35′ W., and upwards of seven thousand feet above the level of the sea. Leaves of dicotyledonous trees, obtained in these beds by Lieutenant Abert in 1847, are figured

The Mackenzie traverses the basin in which the tertiary coal is deposited very obliquely, and the Great Bear Lake River cuts it more directly across.

in Colonel Emory's report to Congress (pp. 522. 547.). Nuttal observed lignite beds associated with the pink-coloured pipe-clay on the Arkansas, somewhere near the 48th parallel. Sir Alexander M'Kenzie states that a narrow strip of marshy, boggy, and uneven ground, producing coal and bitumen, runs along the eastern base of the Rocky Mountains, and he specifies latitude 52° N., longitude 1121° W., on the southern branch of the Saskatchewan, and latitude 56° N., longitude 116° W. (Edgecoal Creek) in the Peace River, as places where coal beds are exposed. Mr. Drummond procured me specimens of coal with its associated rocks at Edmonton (latitude 53° 45′ N., longitude 113° 20′ W.) on the north branch of the Saskatchewan, and, consequently, between the places mentioned by Sir Alexander M'Kenzie. According to Mr. Drummond the coal was in beds varying in thickness from six inches to two feet, and interstratified with clay and sandstone. The examples he selected were precisely similar to the slaty and conchoidal varieties which are found at the mouth of Great Bear River, and the resemblance between the sandstone of the two localities is equally close. He also found a black tertiary pitch coal which breaks into small conchoidal and cubical fragments, which Mr. Small, a clerk of the Hudson's Bay Company, who gave me the first information of these beds, likened well to Spanishliquorice. At Edmonton the more slaty coal-beds pass gradually into a thin, slaty, friable sandstone, which is much impregnated with carbonaceous matter, and contains fragments of fibrous lignite. Hand specimens of this cannot be distinguished from others gathered from the shale cliffs on the Athabasca River. Highly bituminised shale, considerably indurated, exists in the vicinity of the coal at Edmonton, and clay-ironstones occur in the clay beds.

Chief Factor Alexander Stewart told me that beds of coal

The hill on the north side of the last-named river rises about six or seven hundred feet above the water, every where steeply, and in some places precipitously. It is, as has been stated, part of one of the spurs of the Rocky Mountains, a gap in which furnishes a channel for the passage of the Mackenzie. Its base, measured directly across, is about three quarters of a mile. The Great Bear River flows between its south flank and the tertiary coal beds described above; but on its north flank horizontal beds of limestone and bituminous shale appear again. The strata of the hill itself are highly inclined upwards on both its flanks towards its axis, and some are vertical. I did not procure organic remains from any of the upheaved beds forming these ridges or spurs, whereby their age might be determined, but they are evidently older than the limestone and shale formation which abuts against them or covers their edges, and are

are on fire on the Smoking River, which is a southern affluent of the Peace River, and crosses the 56th parallel of latitude, and also that others exist on the borders of Lesser Slave Lake, that lies between Smoking River and Edmonton. There are coal beds on fire, also, at the present time near Dunvegan on the main stream of the Peace River. All these places are near the base of the Rocky Mountains, or the spurs issuing from that chain, and their altitude above the sea varies from 1800 to 2000 feet and upwards. The beds at Great Bear River are probably not above 250 feet above the sea level.

very probably, judging from the scarcity of fossils, of the protozoic epoch.

The Hill at the Rapid, twenty-four miles higher up Bear Lake River, is very similar to the one just noticed, and its beds have the same anticlinal arrangement. It is, as has been already stated, a member of the same spur with Clark's Hill, and from its summit the ridge may be seen extending through a comparatively level country towards the west end of Smith's Bay in Great Bear Lake. The floor of the valley lying between it and the spur at the mouth of the river is well wooded, but is much intersected by lakes, marshes, and considerable streams, some of which fall into the Mackenzie, and others into Bear Lake River. Immediately to

the westward of the Hill at the Rapid, but separated from it by a rivulet, there are horizontal beds of friable sandstone, and beyond them a thick deposit of bituminous shale, which extends northwards into the high promontory of the Scented Grass Hill, that divides Smith's Bay from Keith's Bay in Great Bear Lake. The excavation of the body of the lake terminates the shale formation in this direction, but more to the westward it can be traced onwards to the Arctic Sea.*

* Various detailed accounts of some of the tertiary coal beds, and of the elevated spurs which cross Bear Lake River, are contained in the Geological Appendix to Franklin's Second Overland Journey; and the maps on a large scale, given in that work, may be consulted with advantage by any one who wishes to become well acquainted with the topography of the country, or to trace the course of the ridges here described in the text.

The limestone which forms the body of the hill at the mouth of Great Bear Lake River is blackish grey, full of sparry veins, or brownish-grey and bituminous, associated with calcareous breccia. On the northern flank of the hill, abutting against the vertical beds, there are layers of bituminous shale, some of which effervesce with acids, while others approach in hardness to flinty slate. Underlying the shale, horizontal beds of limestone are exposed for some miles along the Mackenzie, and from them there issue springs of saline sulphureous waters and mineral pitch.

The horizontal sandstone beds, above the Hill at the Rapid, of the same river contain fossils, some of which were considered by Mr. Sowerby to belong to the same age with the English oolitic limestones; but they require re-examination, and then we may learn whether the very extensive bituminous formation belongs to the Marcellus shale or to the lias beds.