The Vegetation of North America 



33^ 



W.S. Cooper 



FlG.^ 203. Forests on a high mountain (Mt. Robson, British Columbia), showing timber 

 on ridges and absent from valleys where the snow accumulates to great depths. On the 

 talus cone are numerous avalanche tracks where the trees have been destroyed. The white 

 line crossing the talus cone near the base is a trail. 



