112 UNIVERSITY OF COLORADO STUDIES 



hydrogen, with 9 . 69 per cent, unaccounted for, which may increase the 

 total amount of carbon somewhat. The Blythe specimens contain 

 about 3 per cent, less of carbon and 1 per cent, more of hydrogen. Some 

 "brown gilsonite" from the same place presented by Mr. Riland is 

 found to be very impure material, containing 15.29 per cent silica and 

 7 . 33 per cent, calcium carbonate. 



The agricultural possibilities of the country vastly exceed the present 

 development. 



The region traversed ranges from 5,000 to 12,000 feet above sea- 

 level, sloping from the mountains above Trapper's and Marvine Lakes 

 westward, and draining ultimately into the Pacific Ocean. 



A partial bibliography appended to this report cites the more impor- 

 tant works relating to the region and its biological and geological phe- 

 nomena. Up to the present time the geology has received much 

 more attention than the biology. 



Remarks on the Climatology of Northwestern Colorado 

 By W. W. Robbins 



General account. — As the area visited by the expedition ranges in 

 altitude from 5,000 feet to 12,000 feet, there are, of course, varied 

 climatic conditions. Climatological data are available for Meeker 

 and Rangely. * These data represent very accurately climatic condi- 

 tions existing over the greater part of northwestern Colorado, exclusive 

 of altitudes above 7,000 feet, for which no data are available. Local- 

 ities below this altitude are dominated by pinyon pine (Pinus edulis), 

 Utah cedar (Sabina utahensis) sage-brush (Artemisia tridentata) and 

 associated plant forms. Even without climatological data, such xero- 

 phytic vegetative types as these indicate semi-arid conditions. Western 

 Colorado in general has a semi-arid climate. It belongs to that great 

 arid district which embraces Nevada and Utah. 



Precipitation. — Meeker has a mean annual precipitation of 16 inches; 

 Rangely 8.8 inches. This difference is due partially at least to the 

 difference in altitude between the two stations. Meeker is 6,182 feet 



1 Annual Summary Colorado Section of the Climatological Service. 



