Nebraska Soils Field Trip - Virginia Tech

4th IUSS Soil Classification Conference Field Tour Guidebook
Glacial till derived soils in MLRA 107B
by: Patrick Cowsert, RSS, Stanton Nebraska
The landscape in MLRA 107B is dominated by a thick deposits of Wisconsin age loess which overlays
pre-Illinoisan glacial till. The pre-Illinoisan glacial period was between 500,000 and 2.5 million years
ago during the early to middle Pleistocene Era. The pre-Illinoisan period was once thought to consist of
two distinct glacial events, however it has had 11 distinct glacial stages identified during that time.
During the post glacial period, a till paleosol developed which was later exposed in some places. The
landscape that developed in the glacial till dictated the larger 1 st order stream valleys prior to, and after,
loess deposition. As the loess landscape developed and the loess blanket was eroded and the secondary
drainage systems developed, the glacial till was re-exposed. In some locations the till is exposed in
isolated areas in the upland sideslopes and in others the drainageways are so entrenched and the degree of
erosion on the side slopes is so great that little or no loess can be found over the till. The exposed till in
some areas has been truncated and the paleo-surface eroded away.
The exposed till is characterized by generally little
sorting with a variety of rock fragment sizes throughout
the soil profile. Many hillsides of glacial derived soils
are scattered with glacial erratics . The till is well
drained, but relict redoximorphic concentrations and
depletions from a previous climatic period are common
with coarse to extremely coarse features visible.
Manganese is associated with the iron in the
concentrations. Calcium carbonate is common and
ranges from free calcium carbonate to soft masses and
nodules to concretions which can be quite large. Many
stones have a rind of calcium carbonate on the lower
side. Some pedogenic development has begun on these
till exposures and soil structure and clay films are present
in some soils.
Pre-Illinoian glacial till is calcareous and it has an
average clay content of 24 to 35% clay and an average
sand content of 20-40% with some pedons as high as
52%. The typical soil texture is clay loam or loam with
loam, silt loam or silty clay loam at the surface. Rock
fragments are generally less than 10% of mixed origin.
Mean annual temperature ranges from 10 to 13 degrees C, and mean annual precipitation ranges from 71
to 86 centimeters with some areas as high as 94 centimeters. Average frost-free period ranges between
130 to 180 days with some areas 200 days.
The glacial derived soils of this area, in order from least to most developed are: Steinauer, Liston,
Burchard, and Shelby. The Steinauer and Liston soils are usually found on more eroded landscape
positions on steeper side slopes and exposed nose slopes (see figure 4). The slope range here is from 5 to
75% slope. Steinauer soils are an AC profile with non-pedogenic free calcium carbonate to the surface.
Liston soils have a B horizon. Next are the Burchard and Shelby soils (see figure 2 and 4). The slope
range is 2 to 40 % slope. Burchard soils have a mollic epipedon and are leached of carbonates in the
upper part. Shelby soils have a thicker mollic epipedon and are leached to a greater depth.
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