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mountain tribes in the Rocky and Mackenzie mountains. These and the other
native tribes live by hunting and trapping and very much in the same manner
as they did before the advent of the white people. They have, however, all
become christianized and are adherents either of the Church of England or the
Roman Catholic church.

GENERAL GEOLOGY
SUMMARY

The Mackenzie basin is underlain in part by rocks of Precambrian age,
forming the western edge of the great Canadian Shield, but to a much greater
extent by sediments of later deposition. The sediments have suffered very little
deformation and, except in the mountains on the western edge of the basin,
display only a few minor elevations.

The Precambrian rocks lie east of a line following Slave river and the
north arm of Great Slave lake and. extending northwest to Great Bear lake.
The greater part of the Precambrian area is underlain by granites and gneisses.
Small areas of older, highly metamorphosed rocks are found, such as quartzite,
slate, and sericite and chlorite schists; there are also later sandstones that have
been intruded by basic igneous rocks. The wide stretches of granite and gneiss
offer little attraction to the prospector, but the older, much altered rocks and
the later basic dykes, sills, and flows may carry metallic minerals in commercial
quantities.

The sediments lying to the west of the Precambrian area consist of
dolomites, limestones, and shales of Silurian and Devonian age, and sandstones
and shales of Cretaceous and Tertiary age. A great unconformity marks the
contact between the Precambrian and Palwozoic formations. Although uncon-
formable relations exist between the Silurian and Devonian rocks, the Devonian
and Cretaceous, and the Cretaceous and Tertiary in the north, there is no
marked discordance of dip except probably between the Tertiary series and the
underlying rocks.

The Devonian limestones and shales which are frequently bordered on the
east by a narrow band of Silurian dolomites and gypsum-bearing beds form a
broad belt stretching from lake Athabaska northward nearly to the Arctic coast.
They are concealed to the south and southwest by Cretaceous rocks, and towards
the delta of the Mackenzie also pass beneath Cretaceous sediments. These later
sediments also overlie the Devonian rocks in long stretches along the Mackenzie
above and below Great Bear river and are exposed to the west and north of Great
Bear lake. The Devonian rocks are in general nearly horizontal east of the
Rocky Mountain front, but within the Rocky Mountain system which the

Mackenzie reaches at about 90 miles below Simpson, sharp anticlinal and:

synclinal.structures prevail.

The Cretaceous sediments resting upon the Devonian rocks at the south
occupy nearly the whole of the valleys of Athabaska and Peace rivers and
probably extend in a northwest direction to Liard river; to the south they stretch
beyond the area dealt with in this report through Alberta and Saskatchewan into
the United States. They consist of a series of sandstones and shales, and are
nearly horizontal in attitude, but dip slightly to the south or southwest in the
basins of Athabaska and Peace rivers. -

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