Nebraska Soils Field Trip - Virginia Tech

4th IUSS Soil Classification Conference Field Tour Guidebook
Stratigraphic, Pedologic, and Paleo-Topographic Relationships on a Glaciated Upland Interfluve Near Lincoln, Nebraska
Philip JJ. Schoeneberger* Schoeneberger and Douglas AA. Wysocki Wysocki, National Soil Survey Center Center, USDA - NRCS NRCS, Lincoln Lincoln, NE
Introduction
Soils are a synthograph, a record of earth system processes that can lead to an
understanding of landscape history, soil geography, and the dynamic processes
that formed them. These insights substantively explain what otherwise
appears to be random soil variability, and can be applied to better manage soil
Methods
Fi Figure 22.
Summary & Landscape History
Site morphology and sediment body composition and configuration detail a
dynamic, varied landscape history. The sequence of layers (from the surface
down; Figure 5) are interpreted as:
and water resources. 0) Anthropogenic land surface modification by removal of most of the
modern mollic surface and exposure of headwalls (borrow-pit activities).
Primary field observations were made along headwalls of an extensive borrowpit
site cut through an interfluve of dissected till plains adjacent to Lincoln,
Nebraska (Figure 1). Cross-sectional documentation is shown (Figure 2).
Standard laboratory analyses were conducted on soil horizons (Burt, 2004).
Results
An upland interfluve was investigated in a loess-mantled, pre-Illinoian glaciated
landscape near Lincoln, NE. The site retains a record of the stratigraphic,
pedologic and paleo-topographic paleo topographic relationships of multiple depositional and soil
development episodes over the last several hundred thousand years. The
sequence of layers (from the surface down; Figure 3) are:
1) Greyish-brown loess [locally colluviated, homogeneous eolian-derived silt
with scattered till-derived gravels, and an oxidized upper portion (including
a black, modern mollic surface) and an intermittent, deoxidized lower
portion].
2) Brown loess (locally colluviated with scattered, till-derived gravels).
3) Pedisediment unit including a reddish-brown paleosol (reworked, loessderived
slope alluvium, including scattered gravels and channel-fills, rather
than primary air-fall loess deposits).
4) Stone line (erosional lag concentration of gravels and stones)
5) Glacial till (3 zones):
a) A truncated, red paleosol developed in the uppermost portion of the
leached, oxidized till. (weathered, reddish, strong pedogenic structure,
leached, in an oxidized, till – derived matrix).
b) Oxidized, leached till (weathered, weak pedo-geogenic structure,
oxidized till matrix).
c) Unoxidized, unleached till (Figure 4) (weathered, with strong geogenic
structure, grey till matrix. The upper 5-10m of the till is dominated by
prominent, deep polygonal fractures. The fractures are lined with a
thin, black Mn / Fe-Mn film along the primary fracture face which is
surrounded by white secondary CaCO3 , which is bounded by a thick
yellow halo (hypocoats) of Fe and Mn oxides. These polygonal seams
are nearly vertical at depth (>5-10m). Near the upper limit of the till
the seams are vertical in proximity to the interfluve axis, but bend
obliquely in a down-slope direction on sideslopes.
Pit 6 Profile Description and Lab Data 1
Figure 1. Figure 4.
Relative Horiz. Soil Co. Matrix Soil Structure Efferv.
Depth (cm) (top 40 cm
Texture Frags Frags. % Color (m) Class
removed) -- -- -- -- -- --
0-10 A sicl 1 10YR 3/1 3,f -m, abk NE
10-40 Bt1 sicl 0 10YR 4/3
& 5/3
2, m-c, sbk NE
DEM of NW 27th & 5/3
40-70 Bt2 sicl 1 10YR 4/3 2, m, pr parts
to 2, m, sbk
NE
70-100 Bt3 sicl 2 7.5YR 4/3 1, co, pr parts
to 1, m,sbk
NE
DEM of NW 27 St. Area 100-130 100 130 Bt4 sicl 2 5YR 3/3 11, mm-cc, pr prparts parts NE
& 4/3 to 2, m, sbk
130-145 2Bt1 extr. gr. l 85 7.5YR 4/6 1, m NE
Figure 3. Pit 6. 145-160 2Bt2 cl 7 7.5YR 4/6 2, m, sbk NE
Figure 5.
160-210 3Bt cl 2 7.5YR 4/4 3 co-v.co pr parts
to o 3, f-m, , sbk sb
NE
210-230 3BC c 2 2.5Y 5/2 3 co-v.co pr parts
to 3, f-m, sbk
NE
230-260 3C c 2 2.5Y 5/2 3 co-v.co pr parts
to 3, f-m, abk
SL
260+
1 Burt, 2004.
-- c 2 2.5Y 5/2 3 co-v.co pr p parts p
to 3, f-m, abk
SL
References
Burt, R. 2004. Soil Survey Laboratory Methods Manual, ver. 4.0. USDA- NRCS, SSIR 42.
Mason, J.A., Joeckle, R.M., Bettis, E.A. III. 2007. Middle to late Pleistocence loess record in eastern Nebraska, USA, and implications for the unique nature of
Oxygen isotope Stage 2. Quaternary Science Reviews: 26 pp. 773-792.
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1) Peoria-aged* loess (>11 to 20 to 50 to 640 ka (Lava Creek –B tephra) to