21 south along the valleys of Peace, Slave, and Liard rivers and the Mackenzie above the mouth of the Liard, is the land sufficiently well drained to be suitable for agricultural purposes. North of this, except on the islands and banks of streams, the surface is generally covered with a thick moss which prevents the ground beneath from ever thawing out beyond a depth varying from 6 inches to 6 feet, A thick forest of small spruce, tamarack, and willows extends over the whole of the lowland to the newly formed land at the seaward edge of the delta. — The southernmost of the ranges which rise out of the Mackenzie lowland is Horn mountain situated north of the Mackenzie between Providence and Simp- son. The mountain is visible from the river all the way between these two points, at a distance of about 20 miles from the river. It has the character of a simple escarpment with a steep face to the south and a very gentle slope to the north.* Its summit stands about 1,000 feet above the sea. The Franklin range, which extends along the east side of Mackenzie river from old Fort Wrigley northward beyond Great Bear river, is considered by McConnell to be an outlier from Mackenzie mountains which does not actually cross the river but marks an entirely new line of disturbance. The Rock-by-the- river-side, however, near the present site of Wrigley, forms part of a small range which strikes in a direction diagonal to the main ranges and connects the Frank- lin range with the main portion of Mackenzie mountains. The Franklin range at its south end rises easily out of the lowland as a narrow wooded ridge. It continues northward in a series of* round-topped eminences flanked in places by plateaus, and, gradually increasing in heighi, culminates in the highest of them all, mount Olark. Mount Clark is a flat- topped mountain situated 8 or 10 miles back from Mackenzie river north of Blackwater river and is estimated by McConnell to be between 3,000 and 4,000 feet in height. From the northern shoulder of this mountain a line of lower elevations extends northward to Great Bear river and crossing it continues in a northerly direction for an unknown distance. A wide gap is cut in the range by Bear river at a point where the highest mountain, mount Charles, is 1,500 feet in height. Several other streams, the most important of which is Black- water river, have their sources on the eastern side of the range and flow west- ward through gaps in it to join the master stream of the Mackenzie. Another of the higher tracts that break the monotonous level of the low- land is Grizzly Bear mountain which occupies the peninsula between Keith and MeVicar bays. The mountain is estimated by Sir John Richardson? to be 900 feet in height, but since many of Richardson’s estimates have been proved to be too low it is probably somewhat higher. Preble® considers it to be- higher than mount Charles which Bell* gives as 1,500 feet. It is a massive, round-topped ridge quite devoid of trees for several hundred feet of its upper portion. Scented Grass hills, on the north shore of Great Bear lake, form the penin- sula between Smith bay and the northern indentation of Keith bay known as Richardson bay. They are a round-topped ridge similar to Grizzly Bear moun- tain in general character and height and terminating to the east in a prominent point known as Gros Cap. | Between the Franklin range and Mackenzie mountains, Mackenzie river flows through a forested plain 20 to 80 miles in width, which, however, is broken 1McConnell, R. G., Geol. Surv., Can., vol. IV, 1888-89, p. 84 D. 2 Narrative, second expedition to polar sea, Appendix, p. ii, 1828. 3 North American fauna No. 27, U.S. Dept. of Agric., 1908, p. -43. #Geol. Surv., Can., vol. XII, 1899, p. 8 C.