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difficulties except those caused by shallow water and a few boulders. In this and
Long rapid, which follows and is easily navigable, the channels are on the right
side of the river.

About 5 miles below Long rapid the river makes a sharp bend, at the end of
which is Crooked rapid, where ledges of limestone project into the stream from
the right side. The channel is on the right side where the only danger is from
the large swells. Immediately below is Stony rapid where the stream flows over
a solid rock bed and is very shallow. The canoe channel follows the right shore.

At the foot of Stony rapid a crossing should be made to the left side in order
to descend Little and Big ‘Cascades which follow. These are caused by ledges of
limestone extending across the river, but they are broken down in places enabling
boats to get through. At Big Cascade a direct fall of about 4 feet occurs on the
right side, but on the other side this is resolved into a series of smaller drops and
rapids that presents no serious difficulty in ordinary high water.

At Mountain rapid, 9 miles below, the river is again obstructed by ledges of
limestone, but it is possible to avoid the rough water by descending the upper
portion on the left side, crossing in the middle over a piece of comparatively
smooth water, and descending the remainder of the rapid on the right side.

Mountain rapid is the last dangerous rapid on the river, though a riffle occurs
2 miles above McMurray at what is known as Moberly rapid.

Clearwater river, which joins the Athabaska from the east at McMurray, is
one of the largest tributaries of the Athabaska, but is navigable without inter-
ruption for only about 40 miles when strong rapids occur.

Below the mouth of Clearwater river, which has an elevation of 815 feet
above the sea, the character of the Athabaska changes. Rapids disappear, and
the Athabaska, enlarging to one-third of a mile or more in width, flows smoothly
at an average rate of 3 miles an hour with a grade as far as Athabaska lake of
about 8 inches to the mile. Islands become numerous, the valley increases in
width, and the banks gradually decrease from an elevation of about 400 feet at
McMurray to the water level at Athabaska iake. The stream enters its delta about
35 miles from the lake and divides farther down into several branches whose
channels are constantly changing as a result of the sediment and other material
carried down by the stream. The distance from McMurray to Athabaska lake js
‘about 175 miles and the only obstructions to steamboat navigation in this
distance are the sand-bars and the shifting of the channel at the outlet.

Tributaries of Athabaska Lake

With the exception of Peace and Athabaska rivers there are no streams
flowing into Athabaska lake that are navigable for more than a few miles without
interruption. On the south shore of the lake the most important streams are
Old Fort, William or Gaudet, and Grand Rapids rivers. These rivers drain a
large area of country south of the lake, but they are all shallow and so inter.
rupted by rapids that they are navigable by canoe with difficulty, and that only
in the high-water stages. :

On the north shore of the lake the streams are all short and none of them
is navigable even by canoe, the reason being that the height of land between
Athabaska lake and the streams flowing northward to Great Slave lake lies only
a few miles north of the shore of the lake.

Stone or Black river which flows into the extreme eastern end of the lake is
a large stream rising in Wollaston lake, at a height of 1,300 feet above the sea.