Characteristics of Wisconsinan Glacial Tills in Indiana and Their Influence on Argillic Horizon Development
1985
Franzmeier, D. P. | Bryant, R. B. | Steinhardt, G. C.
In relatively young soil landscapes the parent material largely controls the properties of soils formed on it. Glaciers of the Tazewell subage (15 000–21 000 yr ago) covered the northern two-thirds of Indiana and glaciers of the Cary subage (15 000–12 000 yr ago) covered the northern third. Particle size distribution, calcium carbonate equivalent (CCE), and calcite-dolomite ratio were determined by standard soil characterization procedures on pedons sampled mainly during the course of the soil survey to represent till-derived soils. These data were grouped into classes according to geographic areas defined by major end moraines and recognized ice-margin positions and by new boundaries that separate areas shown to have different kinds of till in this study. Tazewell-age till is mainly loam in texture and has a CCE between 200 and 300 g kg⁻¹ (20 and 30%), but some in the eastern part of the state has CCE around 350 to 400 g kg⁻¹. The Cary-age till in the north-central part of the state also has loam (to sandy loam) texture and CCE around 200 to 250 g kg⁻¹. In a series of concentric Cary-age moraines in the northeast, average clay content increases from 27 to 37% and CCE decreases from 310 to 170 g kg⁻¹ northeastward, reflecting increasing lacustrine influence in the younger tills. The clay content of the B horizon of till-derived soils is a function of the clay content, CCE, and age of the glacial till parent material.
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