Nebraska Soils Field Trip - Virginia Tech

4th IUSS Soil Classification Conference Field Tour Guidebook
contains only the pre-Illinoisan glacial deposits, which overlie an irregular bedrock surface
(Boellstorff 1978a). The most recent glaciation occurred after 780 ka (Brunhes-Matuayma
paleomagnetic boundary) and before 640ka (Lava Creek B tephra deposition, Yellowstone
Caldera) (Boellstorff 1978 a, b). Subsequent, episodic erosion, however, has greatly modified
the original glacial landforms and loess burial has further muted the glacial expression.
Classically, the pre-Illinoisan glacial deposits were known as Kansan and Nebraskan
(Chamberlain, 1895). A number of studies (Boellstorff, 1978a, 1978b, 1978c; Hallberg, 1980)
identified multiple glacial deposits with intervening paleosols under stable divides in eastern NE
and Iowa. The stratigraphic complexity, lack of chronological control, and the inability to resolve
regional till correlations compelled abandonment of the terms Kansan and Nebraskan (Hallberg
1986).
Loess
Four Pleistocene loess units and one Holecene loess exist in NE. Figure WS2 presents the
general loess stratigraphy with inclusive paleosols and the undifferentiated, underlying pre-
Illinoisan glacial deposits. Youngest to oldest the loesses are Bignell (Holocene), Peoria
(Wisconsin), Gilman Canyon (Wisconsin), Loveland (Illinoisan), and the Kennard formation (pre-
Illinoisan). The Bignell Loess occurs in western NE; it is not a distinct unit in the field area. It
does influence upper soil profile characteristics in eastern NE (Jacobs and Mason 2007). Peoria
Loess is commonly the surficial loess in eastern NE. It is the most widespread and generally the
thickest loess in NE and the Midcontinent.
Figure WS2 Field area Quaternary stratigraphy including paleosols.
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