Genesis of Layer Silicates in Representative Soils in a Glacial Landscape of Southeastern Wisconsin

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Abstract
Quantitative mineralogical analysis of the clays and silts of two representative soil profiles of a glacial landscape indicated the relative extent of depositional influence as well as the effect of mineral weathering. The more intensely leached upland Lapeer loam of about pH 5 has a clay mineralogical content of 20% mica and 12% kaolinite. Clay in the less leached, neutral Saylesville silt loam occurring on a plain at a lower topographic position contains 40% mica and 6% kaolinite, as does the calcareous till under the Lapeer solum. A direct relationship exists between the pH of the horizon and content of mica in soil clay (r = 0.97) for 13 horizons of these and related soils. Variable total sand contents of the different horizons demonstrated the variable origin of the material from which the horizons developed.About 20 cm of loess was incorporated into the Lapeer loam. The Lapeer solum and weathered Peorian loess of Illinois are similar with respect to (i) content of about 2% K2O in the clay fractions, and (ii) a coarse silt/fine silt ratio of about 0.7. The dolomitic lacustrine deposits of the C2 and C4 horizons of the Saylesville soil had a vermiculite/mica ratio in the clay of 0.18. These horizons contain no sand and have clay mineral components nearly identical to those of the sandy loam till of the Lapeer, which has a vermiculite/mica ratio of 0.19.
Funding Information
  • National Science Foundation (GP‐4144)