THE CLYDE SEKIES OF SOILS. 39 



CLYDE SILTY CLAY LOAM. 



During the progress of soil survey work the Clyde silty clay loam 

 has been mapped in 11 different areas located in New York, Ohio, 

 Indiana, Illinois, and Wisconsin. The total area thus far mapped 

 amounts to 401,984 acres. Additional areas of considerable extent 

 will undoubtedly be encountered in these regions during the progress 

 of soil survey work. 



The surface soil of the Clyde silty clay loam to an average depth 

 of 10 inches is a dark-brown to black sticky, silty clay loam. When 

 wet it is a dull black in color and decidedly plastic and claylike. 

 Upon becoming partially dried it assumes a lighter brown or gray 

 or grayish-brown color and usually develops a granulated or crumb- 

 like structure. Nearer the margins of the areas of this type the color 

 is usually a lighter brown, the surface soil may have a depth of only 

 5 or 6 inches, and the admixture of coarser grained material some- 

 times renders it rather more loamy than the typical area. 



The subsoil to a depth ranging from 15 to 20 inches is most fre- 

 quently a dark brown or almost black silty clay loam which becomes 

 gradually lighter colored with depth and at about 2 feet grades into 

 a drab or dark-blue sticky clay loam. This is most frequently under- 

 lain by a yellow or mottled yellow and gray plastic clay loam. 



There is a considerable variation in the depth of the brown or 

 black material overlying the deeper subsoil. In all of the smaller 

 areas of the type, comprising a few acres in a place, the darker sur- 

 face material has a depth of about 1 foot. In the larger areas, com- 

 prising tracts of several square miles in extent, the dark colored, sur- 

 face material usually has a total depth of 18 inches to 2 feet. In all 

 of these there is a tendency toward a thickening of the dark surface 

 material toward the central portion of the different areas of the 

 Clyde silty clay loam. 



Neither stone nor gravel are commonly found in either the soil 

 or subsoil of this type. In some instances small amounts of gravel 

 may be found around the margins of the different areas or under- 

 lying the deeper subsoil. 



The Clyde silty clay loam is most extensively developed in basin- 

 like depressions associated with the upland glacial soils throughout 

 western Ohio and central Indiana. It occurs in the hollows and de- 

 pressions in the rolling area occupied chiefly by the Miami silt loam 

 and the Miami clay loam. It is also found in small ponded or 

 swampy areas associated with the moraines and glacial uplands in 

 New York and Wisconsin. Considerable areas are also found 

 through the Great Lake region, where ancient glacial lakes have 

 become wholly or partially drained. In all cases the areas of the 

 Clyde silty clay loam are marked by nearly level or only slightly 



