394 R. C. Hills—Extinet Glaciers of Colorado. 
nearest point on the Continental Divide. Owing to kaoliniza- 
tion and other causes the rocks bordering the lower portion of 
the district have not retained the characteristic glacial scratches, 
and the only indication of the probable thickness of the Hins- 
dale glacier is the presence of drift material which is abundant 
800 feet above the level of Lake San Cristobal. 
he Uncompahgre glacier was eighteen miles long, extend: 
ing to the foot of Uncompahgre Park and to within a short 
distance of the mouth of Dallas Creek. It deposited the huge 
On the San Juan, Navajo, Los Pifios, Piedra, Florida and 
Dolores, all of which streams I have visited, local glaciers ob 
greater or less extent once existed; but those I have deseribe@ 
were probably the most important, at least their history 1s the | 
best preserved. eae 
uring the period of the extension of the ice sheet the Up 
per and Middle Cretaceous rocks were eroded from 200 to 500 — 
feet, in some places more, the amount of erosion being greater 
where shales Po as for instance, in the section of 
country immediately north of Animas City. a 
That a long period of time elapsed between the retreat of the — 
ice sheet and the final retreat of the local glaciers is show? hf 
