730 ABSTRACTS OF PAPERS 



With reference to the attitude toward the lowaii drift assumed in the other 

 two papers, facts from the field are presented to show : 



1. The lowan drift is. 



2. The lowan drift is young as compared with the Kansan. 



3. The lowan drift is not a phase of the Kansan. 



4. The lowan drift has certain very intimate relations to certain bodies of 

 loess. 



5. The lowan drift has no close relations to the Illinoisan. 



PLEISTOCENE OF THE VICINITY OF SIOUX FALLS, SOUTH DAKOTA 



BY B. SHIMEK 



(Abstract) 



A discussion of the Pleistocene, including the Nebraskan drift (in some places 

 more than 60 feet thick), the Aftonian silts and sand and gravel, the Kansan 

 drift, a bluish post-Kausan loess, and a later yellow loess. The so-called 

 Altamont moraine east of Sioux Falls is Kansan, and no Wisconsin drift was 

 found in the region in question, either in South Dakota or in the western part 

 of Lyon County, Iowa. There is no evidence of Wisconsin gravel trains along 

 the valley of the Big Sioux, the gravels of the terraces being Aftonian. The 

 buried gravel and silt near Sioux Falls, which have been referred with some 

 doubt to the Buchanan, are Aftonian. The mammalian and molluscan Aftonian 

 fossils of the region are discussed. 



PLEISTOCENE OF THE VICINITY OF OMAHA, NEBRASKA, AND COUNCIL 



BLUFFS, IOWA 



BY B. SHIMEK 



(Abstract) 



A discussion of the Pleistocene of the region, including the Nebraskan drift, 

 the Aftonian, the Kansan drift, the post-Kansan loess, and a later yellow loess. 

 A weathered form of the Nebraskan drift is described. The Loveland in 

 places fully 50 feet deep. A comparison of the loess fossils from opposite 

 sides of the Missouri. 



LESSONS OF THE LITTLE YOSEMITE VALLEY 

 BY F. E. MATHES^ 



(Abstract) 



Much of the diversity of opinion as to the eroding power of valley glaciers 

 springs from a lack of definite knowledge regarding the exact manner in which 

 ice excavates. There is still doubt as to which is the dominating process, 

 plucking or abrasion. The Little Yosemite Valley affords unusual opportuni- 

 ties for studies bearing on this point. It is laid in granites of exceedingly 

 varied structure, absolutely massive over large areas, but strongly jointed else- 

 where. The Merced River being a superposed stream, the valley lies athwart 



3 Introduced by W. H. Hobbs. 



