Genetic Implications of B Horizons in Aqualfs of Northeastern Ohio
1974
Ritchie, A. | Wilding, L. P. | Hall, G. F. | Stahnke, C. R.
A sequence of five Aqualfs with B horizons ranging from moderately expressed argillic horizons to moderately expressed fragipans was contrasted by physical, chemical, mineralogical, and morphological means. These soils have developed from illitic-rich parent till deposits of Late Wisconsin-age; they range in clay content from 25 to 47% and in carbonates from 3 to 15%. A noncarbonate clay content of 30% appears to represent a delicate boundary governing the direction of B horizon genesis in these soils. The genesis of the fragipan appears to be primarily a physical phenomenon; micromorphological and structural properties of the fragipan closely resemble those of the parent till. In contrast, volume changes and fabric rearrangement associated with argillic horizon genesis have largely obliterated traces of rock structure present in the parent till. A dual nomenclature is proposed for fragipan-like zones which do not meet the current minimum root-spacing criteria for fragipans. A large part of the in situ clay gain in argillic horizons, cambic horizons, and the upper portions of fragipan zones is attributed to the disintegration of shale lithorelics.
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