PLEISTOCENE GEOLOGY OF THE SAWATCH RANGE, 

 NEAR LEADVILLE, COLO. 



The writers, as students of geology in the University of Chicago, 

 spent two months of the past summer in studying the glacial geology 

 about Leadville, Colo. It is their plan to continue the work next 

 summer. The work was carried on under the direction of Professor 

 R. D. Sahsbury, who was with the writers for a week toward the close 

 of the season's work. 



So far as known, little detailed work on the Pleistocene geology 

 of the region had been done. The maps of the Hayden Survey 

 mark certain areas as being morainic, and Mr. S. F. Emmons, in 

 his monograph,' mentions briefly the effects of glaciation in this 

 area; but otherwise little seems to have been published. 



The work of the past summer was mainly on the east slope of the 

 Sawatch Range. It covered all the area on the Leadville quadrangle 

 of the U. S. Geological Survey, which lay to the west of the Arkansas 

 River, the Tennessee Fork, and the Eagle River. 



TOPOGRAPHY 



The chief topographic features of the region are the two great 

 parallel north-south mountain ranges, the Sawatch Range on the 

 west, and the Park Range on the east. The higher peaks of both 

 rise to heights of more than 14,000 feet. In the trough between 

 these ranges are the Arkansas and Eagle Rivers. The former flows 

 south, and the latter north. These rivers are fed by large numbers 

 of tributaries from the slopes to the east and west, most of the tribu- 

 tary valleys being almost at right anglesto the valley of the main 

 stream. 



GLACIATION 



The area studied is about 350 square miles in extent. Of this, 

 275 square miles show definite effects of glaciation. It is probable 

 that, at the maximum, the ice covered a somewhat larger area. The 

 drift is referable to at least two distinct epochs of markedly different 



^Monograph XV, U. S. Geological Survey, pp. 41-44. 



