38 



SOIL PHYSICS AND MANAGEMENT 



were filled to a greater or less height with gravel and sand. Lake 

 Agassiz, covering a large area in Minnesota, North Dakota, and 

 Canada, represents the former, while Lake Chicago (Fig. 28), an 

 extension of Lake Michigan to the south, and Maumee T.<ake, an 

 enlargement of Lake Erie, are examples of the latter (Fig. 41). 



FIQ. 29. 



Terraces of Frazier River at Lilloet, B. C. Six in number. (Chamberlain and 

 Salisbury, Courtesy Henry Holt & Co.) 



All of the Great Lakes were much more extensive then than now 

 and subsequent drainage lowered the water and exposed parts of the 

 old bed which now constitute lacustrine deposits. These give us 

 some of our best soils. Loess and adobe may be formed, in part 

 at least, in lakes. 



(c) Alluvial. The alluvial, or stream-laid deposits, include, 

 first, terraces, commonly called second bottom or bench lands, that 



Fio. 30. Terrace along Creek, near Rockford. Illinois, showing stratification. (H. W. 



Stewart.) 



