Characterization and Genesis of Pawnee and Adair Soils in Southeastern Nebraska1
- John L. Millet and
- James V. Drew2
Pawnee and Adair soils occur on gently sloping to rolling uplands in southeastern Nebraska. They have clay-textured subsoils and are somewhat similar morphologically except that Pawnee soil has a yellowish-brown subsoil, whereas Adair soil has a reddish-brown subsoil. Montmorillonite and illite are important minerals in the clay fraction of these soils.
Field studies indicate that Pawnee soil has formed in Kansan glacial till whereas Adair soil has formed in poorly sorted and clayey material derived from Kansan till. This poorly sorted material overlies Kansan till and is identified in Nebraska as the colluvial phase of the Loveland formation. The Loveland formation often has a reddish-brown color which is thought to be the result of weathering and soil formation during Sangamon time.
Petrographic data indicate that the subsoil of Adair soil is more weathered than the subsoil of Pawnee soil. These data suggest that Kansan till was protected from weathering during Sangamon time by colluvial and upland (eolian) phases of the Loveland formation. Pawnee soil occurs in places where Kansan till was exposed by subsequent geologic erosion whereas Adair soil occurs in clayey remnants of colluvial-phase Loveland.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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