560 



PROCEEDINGS OP THE ALBUQUERQUE MEETING 



the latter's study and revision of the geology of the region, the completion of 

 investigations begun some years earlier. Mr II. B. Merwin also .accompanied 

 Professor Wolff as assistant, and was associated with the writer in much of 

 the latter's work on the glacial features of the mountains. 



Previous accounts of the Crazy mountains have given little attention to the 

 glaciation of the region. A brief general statement is made in one of Pro- 

 fessor Wolff's papers,' and mention of glacial action is made in the Livingston 

 and Little Belt Folios, United States Geological Survey, by Messrs Iddings, 

 Weed, and Pirsson, who mapped some of the glacial deposits. Mr J. H. Ropes, 

 who accompanied Professor Wolff on one of his earlier expeditions, studied the 

 effects of glaeiation in these mountains, but his unpublished report is not now 

 available. 



In the expedition of 1907, members of the party visited each of the main 

 canyons and many of the smaller ones. Some of the larger branches of the 

 main canyons were followed to their very heads, and studied in detail, but 

 others were observed more distantly, from ridges or peaks that afforded good 

 views into the heads of the major and minor canyons. 



Character of Glaciation 



The continental ice-sheets, which invaded northern Montana, did not extend 

 to the Crazy mountains. The terminal moraine, according to recent studies,^ 

 passes near Great falls and along the north side of the Highwood mountains 

 60 or 80 miles to the north, and stretches away eastward 50 or GO miles north 

 of the latitude of the Crazy mountains to the border of the state. These 

 mountains were, however, locally glaciated and contain numerous examples 

 of the cliff and valley types, and even two or three piedmont glaciers. 



Number and Dimensions of Glaciers 



All the valleys that head well up in the mountains formerly supported 

 glaciers, large or small. In many cases these were comparable in size to the 

 Swiss glaciers of today. The largest were on the south and east sides of t'ue 

 mountains. Cottonwood (Pine) creek^ on the southwest and Big Timber, 

 Sweetgrass, American Fork, and Big Elk creeks on the southeast and east 

 must have had glaciers approximating 10 to 18 miles in length, as indicated by 

 the position of morainic deposits. 



The glaciers of Sweetgrass and American Fork creeks on the east side of 

 the mountains apparently combined to form a piedmont glacier that had an 

 irregularly oval o^ltline, approximately 7 or 8 miles in length from northwest 

 to southeast, and 3 or 4 miles in width, according to the morainic deposits 

 mapped by Messrs Weed and Pirsson.' There seems to have been also a 

 smaller piedmont glacier produced by glaciers from the south fork of Big Tim- 



1 The Geology of the Crazy mountains, Montana. Bulletin of the Geological Society of 

 America, vol. 3, 1892, pp. 445-452. 



2 F. H. H. Calhoun : The Montana lobe of the Keewatin ice-sheet. Trofessional Paper 

 no. 50, V. S. Geological Survey, 1906. 



3 Names in parentheses are those given on the topographic map, when the latter differ 

 from those locally used. 



* Little Belt folio, U. S, Geological Survey. 



