hundred and
twenty miles in length. M'Vicar Bay, the fifth arm of the lake, is
narrower than the others, and being a little curved at its mouth,
appears less connected with the main body of water. The light
bluish-coloured water of Great Bear Lake is every where transparent, and
is particularly clear near some primitive mountains, which exist in
M'Tavish Bay. A piece of white rag, let down there, did not disappear
until it descended fifteen fathoms. The depth of water, in the centre of
the lake was not ascertained; but it is known to be very considerable.
Near the shore, in M'Tavish Bay, forty-five fathoms of line did not
reach the bottom. Owing to the barometers supplied to the expedition
having been broken in an early period of its progress, the height of the
surface of Bear Lake above the Arctic Sea could not be ascertained; but
it is, probably, short of two hundred feet.[20] If this supposition
comes near the truth, the bottom of M'Tavish Bay is below the level of
the sea, and towards the centre of the basin of the lake the depression
is probably still greater. The great lakes, Huron, Michigan, and
Superior, which discharge their waters into the St. Lawrence, are
reported to sink three hundred feet below the level of the ocean; and
the Lake of the Mountains, or Chipewyan Lake and Great Slave Lake,[21]
through which the Mackenzie flows, have, it is highly probable, some
portions of their beds below the sea level.

In the autumn of 1825, I coasted the western and northern shores of the
Great Bear Lake; and in the spring of 1826, travelled on the ice along
its eastern and southern arms, leaving no part of its shores unexamined
on these two surveys, except the north side of M'Tavish Bay. I did not,
however, on these occasions, make excursions inland.

PRIMITIVE ROCKS.--GREAT BEAR LAKE.

At the south-east corner of M'Tavish Bay, primitive rocks form a hilly
range which, at the distance of a mile or two from the shore, attains
an elevation of eight hundred or one thousand feet. The steep face of
the range forms the shore of the lake for fifteen miles, and perhaps
further, on a direction from N.W. by W. to S.E. by E., and is prolonged
on the latter bearing, at the back of the lower country lying towards
Point Leith. The general form of the hills is obtuse-conical, in some
instances approaching to dome-shaped. None of them rise much above the
others, and the vallies between them are seldom wide or deep. At a
distance,