A survey report recently posted by the Office of the State Archaeologist details the results of an archaeological and geomorphological study of the Minnesota River valley, The Minnesota River Trench: An Archeological and Geomorphological Study of its Prehistory and Settlement by Austin A. Buhta, Rolfe D. Mandel, Michael G. Michlovic, Eric C. Grimm, and L. Adrian Hannus. The primary goal of the study was to determine where prehistoric archaeological sites are located within the valley and to determine whether there are settlement patterns present among the primary prehistoric cultural traditions that are present in the valley. The second focus was to evaluate a known, possible, paleoindian site (21LP0011) in the river trench. Excavation at an intact paleoindian site within the valley could help understand some of Minnesota’s earliest occupants and would also provide information on the timing and character of Glacial River Warren, which formed the Minnesota River valley as Glacial Lake Agassiz’s southernmost outlet.
The geomorphological study helped to determine what landforms within the river trench would have been available for habitation at a given period in time and also explained how erosion and channel migration would have modified or destroyed any archaeological sites present.
The archaeological study used information from previously recorded sites along with field survey of 1,446 acres to ascertain site locations within the river valley. Erosion and sedimentation have resulted in a low probability of surficial sites within the valley. Recent work has documented that colluvial and alluvial processes have buried sites in the lower Minnesota River valley under meters of sediment.
This technical report will likely be of more interest to professional archaeologists rather than avocational archaeologists, however the section regarding the excavations at site 21LP0011 is an interesting read. At this site the archaeologists try to determine the age of the major component of the site without the advantage of diagnostic artifacts or datable material recovered from their excavations.
Follow this link to download the report (it is a 13 MB file): http://mn.gov/admin/assets/minnesota-river-report-public-b_tcm36-247477.pdf