Testing the Effectiveness of Ground-Penetrating Radar at Three Dragoon Forts in Iowa and Wisconsin

Abstract

Dragoon fortifications of the 1830s through the 1850s are some of the most important historic sites of the Midwest, built for the supervision of the removal of Indians and the arrival of European American settlers. Ground-penetrating radar (Gpr) surveys at three dragoon forts demonstrate that Gpr varies greatly in its ability to detect fort-era features. The forts surveyed were Fort Atkinson in Iowa, Second Fort Crawford in Wisconsin, and Fort Des Moines No. 2 in Iowa. Fort Atkinson contained numerous early historic features detected by extensive Gpr survey and confirmed by excavation. A Gpr survey at Second Fort Crawford revealed features that correspond well with an historic map of the fort. Extensive Gpr survey of Fort Des Moines determined there is little correspondence between expected fort structure locations and Gpr features; archaeological excavation revealed that fort-era deposits are very ephemeral and buried beneath deep layers of later historic fill. Based on these tests, Gpr appears to be well suited for survey of substantial military fortifications, provided the site has not been extensively disturbed or covered by dense layers of later fill.