FOR1.ST 



The third uroup remains to be considered. From the Snowy 



ill,- .Missouri 1o tin- north, about 100 miles from 



summit to summit, lie tin- Bearpaw Mountains. These are of 



comparatively low altitude yet of sufficient elevation to support 



growth. They practically constitute a culmination of the 



divide between the Milk River and the Missouri. They reach 



an altitude of (iOOO feet and with the Sweet Grass Hills and a 



few other low elevations represent almost the only forested slopes 



within loo miles of the main front of the Rockies in a strip 100 



miles wide below the Canadian Boundary. 



Geologically, of course, the State presents a -reat variety 

 of formations. The eastern half is mainly Tpper Cretaceous 

 (with an extensive coal bearing portion) and Karlv Tertiary. 

 Later Tertiary formations appear in several isolated tracts in 

 the \\vstrrn part, occupying portions of the Flathead. Bitter 

 Root, Blaekfoot. Biir Hole, and other valleys, alternating in the 

 southwest and center with larger areas of the Paleo/oic. The 

 nortliwi-vtern portion from the Continental Divide to the boun- 

 dary and from the British possessions to the head of the Bitter 

 Root Valley is mainly Protcrozoic (AI<ronkiaii > >. The Bitter 

 Root Ranue ;:nd the hi.ijh mountains of the main divide about 

 Butte ;md southeastward through the Absarokas are chiefly 

 trranitir. but the northern ranges are sedimentary. Volcanic 

 I and lavas form a very small portion of the State. 

 The soils derived from these sources are necessarily varied. 

 both lo'-ally and regionally. Over mm-h <f the eastern part of 

 State the vi, il is of that comminuted variety known as loess 

 (18). in many places overlying ulacial drift and now supporting 

 a typical prairie ve^etat ion. mostly Brasses. It is a fertile soil 

 and \\lien broken up and sown to grains yields heavy crops. 

 L'la iation chai-acteri/cs the greater portion of the 

 i morainic deposits are common (9). Many of these 

 I \\ith soil and. while fertile enough when pro- 

 wit h water, aiv usually dry and vei-y difficult situations 

 i-iut life. Deltas at the mouths of canyons, river bottoms of 

 silt, sand OF- heavj Clay, and in varyin_r areas and depths, form. 

 weat ff the divide, a limited part of the vegetal ion-bearin.Lr land. 

 ed "!' transported materials. The sloju-s which, in the 

 f the State support nearly all the coniferous 



