Progress in the Geophysical Delimitation of Fort St. Joseph, Niles, MI

Abstract

Fort St. Joseph was a French trading post built in 1691, later conquered by the English, and used until 1781. The exact location of the Fort was unknown for over a century, until archaeological investigations in 1998 recovered 18th Century artifacts along the southeast bank of the St. Joseph River. The site is located between a mid‐20th Century landfill and a reservoir on the Saint Joseph River. Strata overlying the remains include a 0.3m organic surface layer and a 19th century silty gray plow zone approximately 0.25m thick. Cesium‐vapor magnetometer/gradiometer, GPR, electrical resistivity, and EM induction surveys were employed in 2002 to guide archaeological excavations. All but one of the excavations oriented by the geophysical surveys yielded evidence of the Fort, as reported in SAGEEP 2003. Deposits associated with the geophysical anomalies include burnt pit features, building stones, and a charcoal layer derived from a burnt structure. The magnetometer survey was greatly expanded over the last two years, and additional excavations were made in 2004. At this time, only the boundary of the Fort facing the river has been defined. The surveys can be expanded in the up‐river direction, but the landfill likely covers a significant area of the Fort.