Paleoenvironmental analysis of a late Holocene deposit : Stanton site, west-central North Dakota

The Stanton Site (W1/2NE1/4 sec. 16, T. 144 N., R. 85W.), eastern Mercer County, North Dakota, contains a late Holocene organic deposit in the cutbank of an ephemeral stream on the Missouri Plateau. Strati graphic units of the 104-cm section are, in ascending order: (l) gravel; (2) silty, organic, sandy clay; (3) organic silt; (4) silty, sandy, organic clay; (5) organic silt; (6) sandy, silt, organic clay; and (7) sand. A radiocarbon date of wood from the base of unit 2 indicates initiation of deposition at 325±_115 radiocarbon years B.P. Abundant well-preserved fossils are present in the organic sediments of the Stanton Site, A molluscan assemblage from a measured section consists of 2 species of sphaeriid bivalves, 6 species of aquatic snails, and 8 species of terrestrial snails, including Stagnicola caperata (Say), Aplexa hypnorum Haldeman, Gyraulus parvus (Say), Armiger crista (Linnaeus), Euconulus fulvus {Muller), and Hawaiia miniscula (Binney). A,;:oleopteran assemblage of 43 taxa includes 22 identified species, primarily ground beetles, including Dyschirius setosus Leconte, Elaphrus olivaceus Leconte, Pasimachus elongatus Leconte, Pterostichus leconteianus Lutshnik, and Patrobus stygicus Chaudoir. Interpretation of the fossil assemblages indicates a thickly vegetated, ephemeral, prairie stream. The similarity of faunal components throughout the section, suggests envirornnental stability, including the climatic parameters