62 
VEGETATION OF THE PEACE-ATHABASKA DELTA REGION 
Description of the Area 
Wood Buffalo park ^embraces the larger part of the vast delta deposits 
of Athabaska, Birch, and Peace rivers. These marshy lowlands lie around 
the western end of Athabaska lake and enclose the shallow depressions in 
which are lakes Claire, Mamawi, and Baril (locally known as Deep lake), 
as well as innumerable smaller bodies of water. Although no contour lines 
have been drawn below 800 feet, the data compiled from land surveys and 
aerial photographs indicate that the boundary of the plain is near the 750- 
or 760-foot levels (24, 12). This line' skirts the northern base of Birch 
mountains, and extends northeastward from a point at Birch river, near 
longitude 112° 45", to Peace river in the vicinity of point Providence, near 
longitude 112°. The eastern boundaries are the rocky, Precambrian plateau 
north of Athabaska lake and the uplands that lie southeast of the Atha- 
baska delta. Long extensions of the lowland are to be found in the lower 
valleys of the Athabaska, Peace, and Birch, and along upper Slave river. 
Several earlier descriptions of the region have already been mentioned, 
the best of which are by E. M. Kindle (33), John Macoun (40, 41), and 
Emile Petitot (47). That of Macoun contains excellent notes on the 
vegetation. 
The shallow basin of lakes Claire and Mamawi contains three main 
delta plains, those of Athabaska and Peace rivers being the largest and 
entering from the southeast and north, respectively. Birch river deposits 
its alluvium in the southwestern part. Each of the deltas contains several 
channels now in use, and many others that carry current in flood time or not 
at all. The presence of the large lake, Athabaska, with its relatively stable 
water-level, so near the embouchure of the Peace, causes the current in 
such channels as the Quatre Fourches, Revillon Coupe, and Rocher to change 
direction according to whether the Peace is in flood or not. The channels 
of the two great rivers that are at present most important in the filling of 
the Lake Claire-Lake Mamawi basin are the Embarras from the Athabaska 
and the Quatre Fourches from the Peace. 
The only relief in the plain is afforded by granite outliers of the Pre- 
cambrian rocks to the eastward. These are rounded hills standing like 
islands in the flats, for the most part having very little soil on them, and 
disappearing a short distance west of the Quatre Fourches. They decrease 
in height to the westward, those on the eastern shore of lake Mamawi being 
only a few feet above the general level. The lakes, although of large area, 
average only 4 to 5 feet in depth. As a rule their shores are very marshy, 
but in places where they are exposed to the action of storm waves they are 
cut back and comparatively dry. The abandoned channels of the streams, 
and the ponds formed by the cutting off of sections of the lakes are in all 
stages of filling, in general being drier toward the outer margins of the basin. 
In the valleys of the main rivers are to be found the normal effects of 
meandering; local deposits of alluvium in the form of shore bars and islands, 
and the abandonment of channels. Several small streams, such as Murdock 
creek, flow through the lowlands before entering the main rivers, and have 
their owm systems of alluvial deposits and erosion. 
