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1905] WHITFORD—FORESTS OF FLATHEAD VALLEY 277 
a low terrace has been formed. Dry ravines extending back from 
this lake also have a woody vegetation. The difficulties which trees 
meet in getting a start in a prairie region should be recognized. A 
very large majority of the seeds never germinate, and many that do 
germinate dry out before they have made a good start; and the sod 
also in many instances prevents the seeds from reaching the soil. 
The head of a ravine works back during freshets, undermines the 
prairie sod, and thus disturbs the vegetative equilibrium that had 
been established, offering a place more or less free from competition. 
If seeds fall on one of these bare places and do not dry out before the 
next rain which disturbs more of the soil, they may be buried by the 
moving soil; the seeds thus having the advantage of being planted 
- and supplied with moisture at the same time. If the conditions 
remain stable long enough for the plant thus started to establish 
itself, it may hold its own even though there is considerable movement 
of the soil in the erosive process. Of course only a few plants out of 
the number thus established can exist long in the severe conditions 
_ of drouth that prevail in these regions. 
The large moraine at the foot of the lake is almost destitute of 
trees (jig. 5), but isolated trees of Douglas spruce and bull pine were 
observed on its northern slope, and around them were a large number 
of seedlings, nearly all of which, in spite of their needle-like leaves, 
Were nipped off by the cattle. It is very possible that if it were not 
for the cattle more of the trees would reach maturity, though it is 
doubtful if the increase would be very appreciable. However, if 
a slope was slightly more protected from the drying winds and the 
cattle did not interfere, open stands of both Douglas spruce and bull 
pine might exist. The hillside near the region shown in fig. 6 illus- 
trates the point; it slopes to the north, and the part of it under dis- 
cussion is too high up the cafion of the Pend d’Oreille River to be 
influenced by proximity to the river, though probably trees near the 
"ver are the source of supply for the seeds that stocked the hillsides 
higher up. The bank is too steep for cattle to maintain a foothold 
easily, and except along paths young trees are not eaten by them. 
As one approaches the forest formation to the north and east 
from the south end of Flathead Lake, trees become more prevalent, 
& number of hilly islands (fig. 5) in the lake showing an interesting 
