A Geoarchaeological Overview of South Dakota and Preliminary

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clays, and high energy gravels. Gravel content increased with proximity to the valley wall. At the base of
the Holocene sediments, atop glaciofluvial outwash was a stratified organic pond deposit. Mandel
interpreted the sediments as late Holocene in age, and surmised that early sediments had been eroded
from the valley prior to the late Holocene (Mandel 1993; Fosha et al. 1994).
Level I and II surveys for the CENDAK irrigation project (Haug et al. 1983) encountered four buried
sites in the Upper and Middle James River in three geomorphic contexts: one in a small draw, two in
larger stream valleys, and one on a glacial lake shore. At 39BE115, pottery and bison bone were found
in back dirt from a farm pond excavation, and interpreted as a buried site impact by construction. The
site is on Turtle Creek, in an outwash valley in the Middle James Region. The Kuhl-Poindexter site
(39FK12) is located on a lower terrace of South Fork Snake Creek in the Upper James region. Two
meters of alluvium was exposed in cutbanks and test units. A late prehistoric component is near the
surface, but Woodland ceramics were encountered at an unspecified depth (Haug et al. 1983:72). At
39SP141, in the Upper James Region, artifacts were found at depths of 80-100 cm in a cutbank on the
east edge of Cottonwood Lake. The geomorphology and stratigraphy were not described. At the Majors
Gulch site, 39HD30, cultural material was found at depths of 45-80 cm in cutbanks of a narrow valley
deeply incised into the Wessington Hills escarpment in the Middle James Region (Haug et al. 1983).
Vermillion Basin/Yankton
Mandel (1992) identified DeForest Formation alluvium at 39CL10, on the Vermillion River upstream
from its Missouri River confluence. A cutbank and backhoe trenches exposed a vertically-stacked
sequence of the Gunder, Roberts Creek, and Camp Creek members. Two buried soils are formed in the
upper and lower parts of the Roberts Creek Member, and a soil is also developed into the upper part of
the Gunder Member. Archaeological deposits were present in both the Roberts Creek and Gunder strata.
Radiocarbon ages of 3260, 3240, and 3050 RCYBP were recovered from hearths in the upper part of the
Gunder Member, and charcoal from the Roberts Creek Member yielded radiocarbon ages of 1850 and
1260 from the lower and upper buried A horizons, respectively. The lithology and ages of the DeForest
Formation at the site are very similar to the characteristics of the DeForest Formation in Iowa and
eastern Nebraska (Bettis 1990; Mandel and Bettis 2000).
Northeast Lowlands
Messerli and Donohue (2005) describe the stratigraphy at 39RO10 and 39RO117, located on an
outwash terrace between the Minnesota River and Lake Traverse. Shovel testing to unspecified depths
did not encounter glacial outwash, suggesting that a loamy mantle of some thickness is present on the
sites. At 39RO10, mound-like features and adjacent level ground yielded prehistoric habitation evidence,
not mortuary remains or features. One of the mounds was underlain by a buried A horizon, and the
overburden was interpreted as disturbed topsoil derived from elsewhere on the site. The surface layer,
was interpreted as topsoil storage from constructing the nearby highway, or a post-occupation raising of
the land surface for an unknown purpose.
The buried soil profile is described in detail, but the geologic processes and origin of the mantle are
not discussed. Elsewhere in the report, the authors note that
“Deposits of Late Pleistocene-Holocene loess (i.e., wind-blown sediments) have been noted as thin
veneers atop some lacustrine deposits and near-level areas of glacial till in the Coteau uplands (Flint
1955: 128). These wind-blown sediments of silts and fine sands probably derived from local outwash
deposits (Flint 1955:164)” (Messerli and Donohue 2005).
Little is known of these deposits, including their age, source of sediment, thickness, and correlation with
regional lithostratigraphic units like the Oahe Formation.
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