Five small prehistoric burial mounds located near Birch Lake on Prairie Island in Goodhue county of southeastern Minnesota were excavated in 1968. The secondary burial of adults in shallow pits and unaccompanied by mortuary offerings follows widespread prehistoric patterns in the upper Mississippi valley. The mortuary pottery vessel buried with the single primary burial suggests construction of the mounds during the period of initial Mississippian cultural intrusion, perhaps shortly after 1,000 A.D
