Results are presented from laboratory investigations of Beta horizons (clay-enriched layers found below the B 2 horizons) of selected soils in the Wisconsin-age glaciated region of northern Illinois.Stereoscopic microscopic investigations indicated the peds were microconstructional. This was interpreted to be the result of not only the arrangement of skeletal material in situ, but also the effect of colloidal material which has moved into the horizon from above and deposited on surfaces of grains, peds, and walls of pores to alter the microconfiguration and porosity. Microscopic studies of thin sections showed a rather porous fabric with a large per-Clay migration was suggested as the dominant process in the development of the Beta horizon and it was closely related to the discontinuity in moisture flow at the boundary of the coarser textured substrata and finer textured subsoil.

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Soil moisture characteristics (15 atm., 1/3 atm., etc.) were determined for 31 soil types representing the major great soil groups recognized in Illinois. In addition such physical properties as bulk density and mechanical analysis were also determined for the principal soil horizons. Available soil moisture and field capacity was shown to vary by textural classes for each soil group studied. For example it was found that silt loam soils of the Gray-Brown Podzolic averaged more available moisture in the A horizon than the Brunizems and Planosols. It was found that the available soil moisture was highly correlated with the 1/3-atm. percentage but not correlated with the 15-atm. percentage. The available moisture was controlled principally by the silt fraction.

The morphology, range in expression, and occurrence are described of a clay-enriched layer (Beta horizon) found below the B 2 horizon of selected soils in the area of Wisconsin glaciation in northern Illinois. The Beta horizon, characterized by a darker color and an abrupt, irregular lower boundary, was more pronounced in coarser textured drift, in Gray-Brown Podzolic soils, and in well-drained members of soil catenas.

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