SURVEYS BY THE UNITED STATES BUREAU 125 



their present shore lines. In some cases several distinct terraces, each one 

 marked by an old shore line, are easily discernible, and represent successive 

 stages in the lowering of the water level. The elevation above the lake varies 

 from a few feet to more than 200 feet. The surface of each terrace is usually 

 rolling to level, with a gradual slope toward the lake, but sometimes areas 

 of a rough and broken character occur. The streams which cross these terraces 

 have frequently, by their cutting, produced deep, steep-sided valleys, especially 

 near the lakes. 



The soils of this group vary from typical beach gravels to offshore deposits 

 of heavy clays. The material from which they are derived consists of glacial 

 debris reworked and redeposited in the lakes or along streams. While this 

 glacial material is made up of rocks of widely varying origin, a large proportion 

 of it often consists of the country rock. In the eastern part of the Great Lake 

 region the percentage of sandstone and shale fragments is usually very high, 

 while in the western part more of the igneous rocks are present. This fact, 

 together with differences in drainage conditions, has given rise to several series 

 of soils. 



Clyde series. Dark-colored swamp soils formed from reworked glacial 

 material deposited in glacial lakes. A special use for these soils is the pro- 

 duction of sugar beets, while general farm crops, truck and canning crops, are 

 grown extensively. 



Dunkirk series. Light-colored reworked glacial material occurring as 

 terraces around lakes and along streams. Good general farming soils and 

 especially adapted to grapes and other fruits. 



Fargo series. Black calcareous soils rich in organic matter formed by 

 deposition of material in glacial lakes. This is the most important group of 

 soils in the Red River Valley, and includes exceptional soils for the production 

 of wheat, barley, and flax. While these are the chief crops at present, the soil 

 adaptations are by no means limited to small grain production. Timothy and 

 vegetables may become more important products with the development of 

 markets. 



Hudson series. Light brown to yellowish brown soils, with drab to yellow- 

 ish subsoils. 



Merrimac series. Brown terrace soils underlain by gravel, formed prin- 

 cipally of reworked glaciated crystalline rocks. Leachy soils of low general 

 farming value, but especially adapted to trucking and apple orcharding in some 

 sections. 



Sioux series. Dark-colored soils resting on dark or light-colored subsoils, 

 with gravel beds usually within 3 feet of the surface. The crops produced on 

 soils of this series range from early short-seasoned truck crops through special 

 crops like alfalfa and sugar beets to the wide variety of general farm crops 

 produced in the Central West. 



Superior series. Gray and red soils with red subsoils, formed from reworked 

 glacial material deposited in glacial lakes. Not extensively developed, but 

 known to include fine types for clover, timothy, and small fruits. 



