gical notices follow in the order of
the route of the Expedition.

BEAR LAKE RIVER--SANDSTONE, LIMESTONE.

Bear Lake River is about seventy miles long, from its origin in the lake
till it falls into the Mackenzie, and throughout its whole length, its
breadth is never less than one hundred and fifty yards, except at the
_Rapid_, a remarkable place, about the middle of its course. It is from
one to three fathoms deep, and very rapid, its velocity being estimated
at six miles in the hour. Its waters are clear as they issue from the
lake, but several branches of considerable size bring down muddy water,
particularly one which flows from the north, and falls in below the
rapid.

Above the rapid, the valley of the river is very narrow, the banks every
where sloping steeply from the level of the country. Their summit line,
which is nearly straight, is about one hundred and fifty feet above the
bed of the river. In some places they have an even face elevated at an
angle of about forty-five degrees, and they are not unfrequently cut by
ravines into pretty regular figures, resembling hay-ricks, or the
parapet of a fort, the ravines representing the embrasures. Sections
made by the river presented generally sand or clay; the sand probably
proceeding from the disintegration of a friable, gray sandstone, which
showed itself occasionally in a more solid form. The rapidity of our
voyage, however, afforded us little opportunity of searching for the
solid strata which are generally hid by the debris of the bank. About
twelve miles above the rapid, a small-grained, friable sandstone, of a
yellowish gray colour, and irregular earthy fracture, is associated with
beds of bluish-gray slate-clay. These beds consist of concretions of
various sizes and irregular shapes, but which may be said to approach in
general to a depressed orbicular form; their surfaces are coloured
purplish-brown by iron, and studded with crystals of sulphate of lime.
This slate-clay contains many small round grains of quartz, and is
exactly similar to that which occurs at the rapid, and which will be
afterwards noticed. In other places the banks are covered by the debris
of a slate-clay slightly bituminous, resembling wacke in its mode of
disintegrating.

The _Rapid_ is caused by the river struggling through a chasm bounded by
two perpendicular walls of sandstone, over an uneven bed of the same
material. On escaping from this narrow passage, it winds round the end