1907] 



YOUNG— FOREST FORMATIONS OF COLORADO 



339 



as a part of one or both of the two just named. Since, however, they 



occupy a definite zone, between 2400 and 



3000 



tn 



, only occasionally 



straying up to 3300™, which zone is not coincident with that of either 

 of the two others, I have decided so to consider them. 



t 



I 



Fig, 7. — Piniis Mtirrayana and Pseudotsuga timber near Nederland, Colorado; 

 approximate altitude 2550^. 



This formation occupies the dry mountain sides and is absent 

 from the canon bottoms. In the former situations it frequently 



mingles with the Pseudotsuga -Picea and 



Picea- Abies formations. 



Its habitat, ho\vever, is distinct from that of either of these. While 

 this formation is much broken, alternating with the Carex-grass-shrub 



