800 Wisconsin Academy of Sciences, Arts, and Letters. 
hills and ridges are miniature lakes, swamps and kettle holes,, 
conclusive evidence of the presence of the great ice sheet. East 
of these hills and extending to Lake Michigan, the surface of 
the counties varies from level to gently rolling. 
The Soil Survey above quoted recognizes soils belonging to 
three series: the light-colored drift soils belonging in the Miami 
series, the dark;-colored drift soils belonging in the Marshall 
series, and the glacial lacustrine deposits belonging in the 
Clyde series. Twelve soil types are recognized and mapped. 
The Marshall clay loam, occupying 33.8% of the land sur¬ 
face, is the predominating soil type of Racine Co., and is found 
throughout the eastern two-thirds of the county. This soil is 
derived primarily from glacial till which at some former time 
was in a wet or swampy condition, thus favoring the growth 
and decay of Water-loving vegetation and giving the soil its 
high organic matter content. 
The predominating soil in the western townships is the Miami 
loam, occupying T9.3% of the land surface of Racine Co. This 
loam is a glacial till formed by the weathering of the till. The 
drainage is very good, and on the ridges and steep slopes, where 
it is excessive, the soil has been removed and the underlying 
clay or gravel exposed. 
The Miami gravel is found only in the western part of the 
county, occurring as well-rounded hills and knolls, and also as 
narrow, choppy ridges. It is especially in evidence around 
Burlington. The surface soil is often lacking, the knolls or 
ridges forming a huge heap of unsorted gravel and bowlders. 
It is of glacial origin, and consists almost wholly of morainic 
material. 
Nearest Lake Michigan, and occupying the bluff rising 20 to 
40 ft. above the surface, lies the Dunkirk fine sandy loam. It 
is of course lacustrine in origin. Next farther back from the 
Lake is the Clyde fine sandy loam, its origin being the same as 
the Dunkirk. The fine sands composing these soils were de¬ 
posited upon the ancient lake floor at the same time, but the 
material constituting the Clyde remained in a swampy condi¬ 
tion for a greater period and more organic matter was incor¬ 
porated with the soil. 
