INDIAN MOUNDS IN LOUISIANA: APPLICATIONS OF MAGNETIC SUSCEPTIBILITY AND ELECTRICAL RESISTIVITY TO GEOARCHAEOLOGY

The Mississippi River Valley floodplain contains some of the earliest records of Native American inhabitance, extending back at least ~6200 years B.P. The state of Louisiana contains over 7,000 mounds of cultural significance, many of which have not been fully examined or described. The Richland (16WF183) and Holloway (16TA32) Mounds were examined using magnetic susceptibility (MS) of sediment cores and electrical resistivity profiles across the surface to determine the composition, methods of mound construction, and to potentially identify anomalous features in the subsurface. Two cores were taken from each mound, extending to ~3m depth, and two electrical resistivity pseudosections were made extending from off-mound to on-mound areas, providing resistivity pseudosections extending to ~4m depth. Within each mound, MS and resistivity data correlated well, and anomalous MS zones were visible in pseudosections. The Richland and Holloway Mounds differ markedly in the preserved magnetic features: the Richland Mound contained an extensive anomalous area, while Holloway Mound contained two distinct and isolated anomalies. The overall morphology and mound preservation, combined with resistivity and susceptibility data support the hypothesis that mound construction was conducted by two different mound-building cultures, each with different uses for these mounds, with different methods of construction and with different sediment sources. Analysis of the data reveals potential fired horizons within the Richland Mound, and possible burials within the Holloway Mound. Applying a combination of minimally destructive and non-invasive geoarchaeological techniques to these mounds has allowed us to characterize these previously poorly defined historical sites without significantly altering the site context.