GENERAL FOREST ASPECTS 



87 



higher here than in the preceding sections, a fact correlated with 

 the dryness of the region. The floor of the valley is almost de- 

 void of the species cited and the foothills are mostly bare, rising 

 to the scattering pines at about 3500 feet. The whole section 

 is distinctly in contrast to the northern portion of Number 3 

 on the opposite side of the Bitter Root Range. 



The Hellgate Section is the seventh of the series. It em- 

 braces the drainage basins of the upper Clark's Fork (formerly 

 called the Hellgate) and the Blackfoot. On the east and south 

 it reaches to the Continental Divide, which forms a huge arc 

 about the heads of these streams and their principal tributaries. 

 The western limit of this section is the Bitter Root Valley. The 

 whole area is nearly 8000 square miles. It rises gradually to 

 the eastward for about 80 miles, from an altitude of 3200 feet 

 near Missoula to 6000 to 8000 on the crest of the Divide. It is 

 a region of comparatively light rainfall and moderate tempera- 

 tures. Prairie and forest alternate according to slope and ex- 

 posure and the forest is often open and the trees of medium size. 

 The upper valley of the Blackfoot widens out at 4000 feet into 

 a broad basin twenty miles or more across, treeless and rela- 

 tively arid. The upper Hellgate valley presents much the 

 same appearance. Much of both basins is covered with 

 glacial gravels, and drumlins are common especially in 

 the valley of the Blackfoot. The grass range is extensive, and 

 the rolling foothills gradually merge into the wooded slopes 

 which extend from 4000 or 5000 feet to many of the high sum- 

 mits. 



Table 15. Forests of the Hellgate Section. 



