49 
had so dissected the clays that they exposed the more permeable sandy 
layers beneath. The action of the prairie vegetation, increasing the water- 
holding capacity of the soil and opening the upper layers to seepage, 
together with the facilities presented by the sands for carrying away the 
now decreased run-off, have entirely eliminated running water and exposed 
the sandy bottoms as the most xerophytic habitat in the vicinity. The 
abundance of ant hills is further evidence of the dryness of the soil. The 
depth to which the permeable layer goes is not known. A creek bed 6 or 
8 feet deep was observed to be in a ponded condition with wet meadow 
vegetation, indicating that in its locality the layer is not a thick one. The 
same type of topography has been observed in the prairies north of Pine 
lake and in those near Salt river, south of Heart lake. 
Although no detailed collections have been made by the writer in the 
prairies in the Grassy Slough district or from their extensions northwest- 
ward, descriptions given by other travellers indicate that the flora is quite 
similar to that just described (33, 63, 65). Some small prairie openings a 
short distance north of Pine lake were studied in 1928, and appeared to be 
small outliers of the larger ones farther northward. They were much modi- 
fied, however, by local fires and from being used extensively as buffalo 
wallows. Some of these openings have sandy soils and but few elements of 
the prairie vegetation, and may be the result of long-continued wallowing 
by the buffalo. Wallow areas on jackpine ridges, where the trees are being 
killed off, have already been described, but further study is needed before 
such a correlation can be verified. The herbaceous and shrubby species in 
some of the open spaces are derived almost wholly from the neighbouring 
woods. 
PRAIRIES AT PEACE POINT 
As the trail approaches Peace point from the north it leaves the last 
sand ridges at about 5 or 6 miles north of the river and descends to the 
present w;ater level by three bluffs, or escarpments. The uppermost one is 
not prominent, but is said to be more so farther to the eastward. The middle 
one, about 50 feet high, is abrupt and subtends the present “ point ”, appear- 
ing at the bank of the river above and below. The sketch map (Figure 5) 
shows the general topography of the area. The third bluff is at the present 
bank of Peace river, where it is formed of a broken cliff of gypsiferous 
limestone that stands about 50 feet above the stream. The prairie open- 
ings are on the plain of the top of the third bluff, where their distribution is 
shown by the map. The vegetation on the upper levels is composed of 
willow clumps, mainly Salix Behbiana, scattered stands of aspen, and local 
muskegs. 
The soil of the prairie is a clayey loam about 2 feet deep, with some 
Glacial boulders in it. The upper part is black from humus materials, shad- 
ing off so that the lower third is reddish brown. The upper part is en- 
meshed with a tangle of roots, mainly those of grasses. In a recently 
formed sink-hole about 6 feet deep, the lower 4 feet was in nearly horizontal 
layers of soft, much-broken, gypsiferous limestone. Sink-holes are abun- 
dant throughout, some with water and slough vegetation in them and some 
quite dry. 
