Clay Mineral Distribution in the Hiawatha Sandy Soils of Northern Wisconsin1

B. E. Brown and M. L. Jackson
Department of Soils, University of Wisconsin, Madison
1 This work was supported in part by the University Research Committee through a grant of funds from the Wisconsin Alumni Research Foundation.

Abstract: Mineralogical analyses were made of the day, silt, and sand fractions of the Podzols Hiawatha loamy sand and Hiawatha sand. The layer silicates show chemical weathering as a function of depth in both soils. A high charge dioctahedral montmorillonite was dominant in all fractions (−5µ) of the A2 horizon and its origin was attributed to weathering of an interstratified vermiculite-chlorite similar to that in the B2 horizon. The 2 to 0.2µ fraction of the Hiawatha loamy sand B2 horizon contains 14 percent chlorite and 18 percent vermiculite with no montmorillonite, and the Hiawatha loamy sand A2 horizon contains 33 percent montmorillonite with little interstratified chlorite-vermiculite. Quartz also showed a soil depth function in the fine silt. It is higher in amount in the A2 than the B2 horizon, attributable to its relative stability in the Podzol A2. Below the B2 it drops markedly in amount, attributable to a difference in silt deposition.

The similarity of ratios of resistant heavy minerals (greater than 2.95 sp. gr.) in different horizons indicates uniform origin of the sand fractions of these soils. Light mineral contents in the sand fractions for all analyzed horizons are also similar. However, particle size data indicate silt and possible clay addition to both the A2 and B2 horizons.

Depth functions in these soils are developed to a marked extent, apparently owing to (1) low amount of fine fraction originally present for weathering, (2) greater amount of water cycled through the A2 than the B2 horizon, (3) rapid and frequent cycling of available water owing to coarse texture, and possibly (4) effects of podzolization. The Omega, Ahmeek, and Iron River soils of northern Wisconsin also showed a similar though not so marked tendency to accumulate montmorillonite in the A2 horizon.

Clays and Clay Minerals; 1956 v. 5; no. 1; p. 213-266; DOI: 10.1346/CCMN.1956.0050118
© 1956, The Clay Minerals Society
Clay Minerals Society (www.clays.org)