60 NATURE AND PROPERTIES OF SOILS 



but also from the unconsolidated till sheet over which it 

 flowed. As a consequence there were in the glacial lakes 

 deposits ranging from coarse delta materials near the shore to 

 fine silts and clay in the deeper and stiller waters. Such 

 materials now cover large areas, not only in New York state 

 and along the Great Lakes, but also in the Red River Valley 

 and in the valleys of the Rocky Mountains and the Cascades 

 and Sierra Nevadas. They make up by far the most im- 

 portant of the lacustrine soils. Glacial lake soils probably 

 present as wide a variation in physical characteristics as any 

 of the great soil provinces. Being deposited by water they 

 have been subject to much sorting and stratification, and 

 range from coarse gravels on the one hand to fine clays 

 on the other. They are generally found as the lowland soils 

 in any region, although they may occur well up on the 

 hillsides if the shores of the old lakes encroached thus far. 

 The color of such soils varies from gray to black, according 

 to the degree of organic matter present. The organic con- 

 tent of such soils, as with the glacial till, varies with climate, 

 and may be high, low, or medium according to conditions. 

 The thickness of glacial lake deposits is variable, ranging 

 from a few to many feet. In chemical composition they 

 closely approximate the soil material from which they were 

 derived. This is particularly true as regards the presence 

 of lime. The distribution of glacial lake deposits is not 

 only wide but the areas are large enough to be of great 

 agricultural influence. Extending westward from New 

 England along the Great Lakes until the broad' expanse 

 of the Red River Valley is reached these deposits have pro- 

 duced some of the most important soils of the northern 

 states. They are valuable not only for extensive cropping 

 with grain and hay, but also for fruit and trucking. 



34. Lacustrine soils — recent lake. — While the glacial 

 lake deposits were formed many thousands of years ago the 

 lake soils of the second group are still in process of construe- 



