SEDIMENTOLOGICAL INTERPRETATIONS OF LANDSCAPE DEVELOPMENT IN THE BUFFALO RIVER VALLEY: MSUM REGIONAL SCIENCE CENTER IN WEST-CENTRAL MINNESOTA

This collaborative study completed in conjunction with Archaeologists at MSUM, Geomorphologists at Wisconsin Eau Claire, and Geologists at North Dakota State University focuses on landscape evolution in the area now occupied by the MSUM Regional Science Center (“RSC”), 13 miles east of Moorhead, MN. Analysis thus far has included sedimentological analyses of pit excavations, description of river cuts, examination of sediment cores, and sieve analysis of bulk sediment samples.

Study sites occur primarily in the incised valley margin of a glacio/deltaic complex developed on the eastern margin of glacial Lake Agassiz. Modern soils developed on aeolian sheet sands directly overlying fluvial gravels, which are underlain by sediments interpreted as offshore bar forms. These deposits lie west of a major shoreline of glacial Lake Agassiz. Understanding paleotopography in relation to geomorphic history may enhance the ability to predict the location of archeological sites. Buried and partially developed soil horizons have been identified by field examination of excavated profiles, and these may be important for the recovery of artifacts that date back to the Early Archaic. Proximity of fluvial gravels appear to act as an erosional barrier allowing for the preservation of paleo-topographic highs (offshore bars). Thicker aeolian sands accumulate in close proximity to these preserved bar forms and appear to favor the development of buried horizons. Both OSL and 14C dates are being analyzed to build a chronology for correlation of buried soil horizons. The offshore bars are a key factor in predicting the location of archaeological sites and understanding how the landscape has changed over time.