ILLUSTRATIONS (Continued) 



ure Page 



L'7. South exposure iii upper Hitter Root Mountains 138 



:>. Yellow pine mi \Yildhorse Island in Flathead Lake 140 



In tli.- valley of the Swan River 142 



:'.i' In tin- Priest River Valh-y in northern Idaho 144 



Lan-h and pine on the east shore of Flathead Lake 



Frontispiece 

 :'<_ A mountain valley in the upper Bitter Root 146 



Distribution <>f larch along snow drifts 148 



'24. A north mountain slope near Missoula 150 



KnenistiiiLr lichen vegetation on the talus 152 



36. A "slide-rock" slope in the upper P.ittcr Root 154 



37. I'uiv stand of Kiiirelmann spruce in Avalanche Basin.... 156 



38. AVrst.-m slope of the Mission Range overlooking Flat- 



head Lake 158 



39. A burn heiuir reoeeupied by lodgepole pine 160 



40. Lnd-epole forest at top of Continental Divide 162 



41 Summit of the Bitter Root Mountains 164 



41'. A typical sub-alpine park in the Swan Range in July.... 166 



At an altitude of 6200 feet in the Swan Ran-e 168 



il A cinpir lake in tin- Swan Range 170 



45. Section of stem of small fir showing rate of growth... . 172 



