38

= The water of Great Slave oo in the east and north arms is clear and prob-
ably deep. In the west arm, however, it is shallow and never entirely clear, as
some of the sediment brought down by Slave river remains in suspension and
drifts slowly westward towards the head of Mackenzie river:

Ice forms in the lake along the shores about the middle of October, but the
middle of the lake frequently remains open until the end of November. In the
spring, channels open along the shore early in June, but in the main body of the
lake ice often remains until July 1 and in the east arm until somewhat later.

Great Bear Lake

Great Bear lake is the next largest of the great lakes of the Mackenzie basin,
having an area of about 11,400 square miles. Its shores chave never been
completely or accurately surveyed and for its delineation we are indebted mainly
to Sir John Richardson* in 1825 and 1826 and to J. M. Bell? in 1900. I is very
irregular in shape and is formed by the union of five arms in a common centre.
Its greatest diameter from east to west is about 170 miles, and in a northeasterly
direction from the bottom of Keith bay to the end of Dease bay is about the same
distance. The greatest depth of water in the lake has never been ascertained, —
but in Smith bay a sounding by Bell? with 281 feet of cord did not reach bottom,
and Richardson‘ states that 45 fathoms of line did not reach bottom in McTavish }
bay.

The shores of the lake are in general low. Ranges of hills approaching
1,000 feet in height, however, occupy the peninsula between MeVicar and
Keith bays and that between Richardson bay and Smith bay. The’ shores of
McTavish bay too are bold and rocky, often rising sheer out ‘of the water for
hundreds of feet. “The southern and western shores are well wooded, while its
northern and eastern borders are more thinly forested. The immediate shores are
mainly of sand and gravel and are usually devoid of trees, but are well clothed
with willows and various ericaceous shrubs and herbaceous plants. In most places 4
along the south shore this treeless stretch is only a few hundred yards in Width: 4m
and in the bays the forest extends to the water’s edge.” i

The drainage basin of the lake is small in comparison with the size of the
lake itself and there are consequently few streams flowing into it, all of which
are short and rapid. Dease river at the extremity of Dease bay and Camsell
river at the southeast corner of McTavish bay are the best known tributaries.

The water of Great Bear lake is light bluish in colour and so clear and trans-
parent that Richardson states a white rag dropped into the water was visible until
it reached a depth of 90 feet.® ae

Ice forms along the shores of the lake and in the bays early in October, but.
the centre of the lake is not frozen over until the beginning of December. .The
outlet of the lake, however, frequently remains open throughout the winter. By
the middle of June the ice begins to break up along the shores, but drift ice some-
times obstructs navigation in the main body of the lake until the end of July.

1 Narrative second expedition to polar sea, Appendix, 1828.

2Geol. Surv., Can., vol. XII, pt. C, 1899. j

3 Geol. Surv., Can., vol, XIII, 1900, p. 99 A.

4 Op..cit., p. ti. : es :

5 Preble, E. A., North American fauna, No. 27, U.S. Dept. of Agric., 1908 p. 43
6Narrative second expedition to polar sea, Appendix, p, ii, 1828. eae 4