71 
The maps indicate the way in which the willow ridges reach out into 
the delta along the watercourses, appearing in large, continuous areas only 
on higher ground where they gradually give way to poplar and spruce. 
On the low delta flats adjacent to the Dog Camp (Figure 10) nearly 
all of the land is still in the meadow and slough condition, and the willows 
are limited to the levees near the mouth of the present Quatre Fourches 
channel, a strip along the lake margin in discontinuous lines, and to the 
slightly raised levees at the former mouths of the little creek that exists 
now only as a Carex slough. This small creek appears to have had at least 
three openings into the lake along this shore, each of which is indicated 
now only by the low levees and the remains of the slough channels. The 
only one of these mouths at which willow groves of any size have formed 
is the one at the Dog Camp. The granite hills in this vicinity seem to have 
caused, probably by eddy currents in the former outwash, higher ridges than 
occur elsewhere, resulting in the greater prominence of the willows. The 
activities of the present Quatre Fourches, along with those of the small 
stream that originally had its beginning farther eastward in another branch 
of the Quatre Fourches, have cut off the shallow ponds from the main lake 
by the coalition of their lakeward deposits. Similar coalitions are shown 
in the delta of Cree creek, now in a state of arrested development due to 
the alteration of the main channels of the Athabaska. Branches at the 
mouth of this creek (Figure 9) show ponds in process of being cut 
off and others not far back from the shore. The second eastern branch of 
the creek above the mouth shows clearly the way in which willow-covered 
levees were left stranded when the channel ceased to function. The willow 
clumps at the Dog Camp must have had the same origin. 
Higher in the delta the last areas to be overgrown by willows are the 
sloughs that have arisen as the ponds above mentioned. A treatment of 
this process will be found in the discussion of slough vegetations. 
Where larger and more active streams are building levees far out into 
the lakes, as at the Quatre Fourches and Embarras, the pioneering willow 
listed above, Salix planifolia , is replaced wholly or in part by the sand-bar 
willow Salix interior var. pedicellata. This species is the commonest 
throughout the more actively developing flood-plains of the region. 
TREE ASSOCIATIONS 
As shown by the map, the first tree growth in the delta occurs as iso- 
lated patches of balsam poplar Populus tacamahacca along the hanks of the 
streams in the upper parts of the willow area. Alders Alnus incana appear 
among the willows before the poplars and form a transition species between 
the two types of vegetation. The poplar association is widespread through- 
out the flood-plains, and is merged with spruce forest in all sorts of com- 
binations. 
Primary spp.: Populus tacamahacca 
E guise turn pratense 
Salix Bebbiana 
Secondary spp.: Picea glauca (young trees) 
Salix arbusculoides 
Alnus incana 
Actaea rubra 
Rosa acicularis 
