ABSTRACTS OF PAPERS 49 



Tibet. But we suspend judgment on this point until fresh specimens arrive, 

 which are promised. 



II 



The loess is almost everywhere distributed around the margin of glaciated 

 areas where it would be naturally brought by the floods of the waning ice- 

 sheets. 



1. This is clearly shown in the publication of the twenty-sixth volume of the 

 Iowa Geological Survey, where it appears that while the area occupied by the 

 Wisconsin ice lobe is free from loess, it is accumulated over sharply defined 

 areas to the east, to the south, and to the west. Such a distribution could not 

 have been produced by the prevailing winds. 



2. My own observations indicate a similar relation to glaciated areas both 

 in Europe and in Asia. The southern plains of Russia are covered with loess 

 related to the advance of the great Scandinavian ice-sheet very much as those 

 of Iowa are to the Wisconsin ice-sheet. This I had noted especially at Kiev, 

 on the Dnieper, and at Rostov, on the Don. In Asia the evidence is specially 

 convincing at Samarkand, where the Zerafshan debouches from the Ali Tagh 

 mountain range, which still supports glaciers, and at Tashkent, where the 

 Chircik and the Keles, branches of the Syrdaria, come down from the north- 

 western projection of the Ala-tau range. The Chinese deposits are, on the 

 original theory of Pumpelly, similarly related to the glaciated area of Tibet. 



3. Extensive and minute studies, by Miss Luella A. Owen, of the snail shells 

 distributed through the loess at Saint Joseph, Missouri, show that they are 

 species of snail which delight in moisture and are favored by a cold climate. 

 Moreover, these species are still living in the small streams at the base of the 

 loess cliffs at Saint Joseph. 



4. The distribution of the loess in these localities by water is made conceiv- 

 able and reasonable by the facts which have accumulated, which indicate 

 enormous floods during the closing stages of the Glacial epoch and also exten- 

 sive variations in land levels connected with the period. 



Presented by title in the absence of the author. 



VALLEY GRAVELS OF NORTHWESTERN lOWA^ 

 BY JAMES H. LEES 



(Abstract) 



An extension and continuation of studies on gravel deposits of Crawford 

 County, Iowa, begun by the writer ten years ago. These gravels were origi- 

 nally thought to be Aftonian, but showed no features supporting such a hy- 

 pothesis, and the writer reached the conclusion that they were Buchanan or 

 Yarmouth or later. More recently Carman has studied these gravels in con- 

 nection with his studies on the Pleistocene Geology of northwestern Iowa, and 

 has discussed them in Iowa Geological Survey, volume XXVI, pages 380-414. 

 The present study extends the investigation farther south and east than was 



^ Printed with pei-mission of the State Geologist. 

 IV — P>uM,. Geol. Soc. Am., Vol. .32, 1920 



