Large-scale geophysical reconstruction of man-made ground at former industrial iron-furnace plantations

Abstract

Blast-iron-furnace plantations were widespread throughout colonial and postcolonial America and therefore represent sites of specific archaeological interest. Because such plantations often were a really extensive, historical reconstruction of a site is challenging using conventional archaeological field techniques alone. Therefore, we appraise the usefulness of integrating magnetic gradiometer, electrical-resistivity tomography ͑ERT͒, and electromagnetic ͑EM31͒ data in detecting and delineating buried structures related to former operation of the Shade furnace, a typical industrial plantation in 19th-century Pennsylvania. The geophysical results were ground-truthed in seven locations by archaeological excavation. Geophysical results demonstrated that ͑1͒ the distribution of remaining original soils could be mapped; ͑2͒ waste materials ͑e.g., slag, used brick, burned charcoal, iron ore, and broken-up sandstone or limestone͒ within or above the original soils could be detected and delineated, whether the material occurred in pits or lenses or was dispersed across the ground surface; and ͑3͒ the location and spatial extent of many former structures related to furnace operation could be identified, such as building or bridge foundations and casting-related structures ͑e.g., the tapping channel or the casting floor, and the former courses of a water canal ͑raceway͒ and a supply road͒. We conclude that geophysical techniques can play a key role in reconstructing man-made ground at former industrial furnace sites in North America.

An assessment of lithostratigraphy for anthropogenic deposits

“…A range of techniques including resistivity imaging, ground penetrating radar (GPR) and gravity surveys are used in archaeological, engineering and environmental studies to delimit and characterize anthropogenic deposits (Fenning & Williams 1997;Guerin et al 2004;Kulessa et al 2006;Boyce et al 2009;Boudreault et al 2010). GPR, in particular, is used extensively by archaeologists to characterize anthropogenic deposits on a site scale (Bladon et al 2011).…”