GEOARCHAEOLOGICAL INVESTIGATIONS AT MOUND Z, MOUNDVILLE, ALABAMA (1TU500)

Earthen mounds are usually conspicuous archaeological features on the landscape in the southeastern United States. Many of these monumental constructions, built during the Mississippian period (an archaeological period dating to approximately A.D. 1000–1400), can reach heights of up to 20 m or more. Moundville (ITU500), in west central Alabama, is a Mississippian mound complex consisting of at least 32 mounds, constructed around a large plaza area. In addition to the major, plaza-periphery mounds, LiDAR data and a 1930’s topographic map of Moundville indicate the presence of a number of possible minor mounds located across the site. Here we discuss one of these, Mound Z, located along the eroding riverbank of the Black Warrior River, and use geoarchaeological methods to determine whether it is a natural landform or an intentionally constructed minor mound.

Using a combination of auger test units, shallow geophysics, and micromorphology we examined the internal structure of this landform. Archaeological excavations on the flank revealed a clay layer beneath the sandy soils of the mound. Auger tests indicate that this clay layer is a flat-lying deposit underlying the full extent of the mound. Ground penetrating radar surveys revealed that this clay layer was confined to the areas immediately surrounding Mound Z, and micromorphology analysis suggest that this layer was not naturally deposited. Together these data suggest that this clay layer was a prepared surface, intentionally deposited prior to the construction of the mound. Ceramic pottery recovered from the excavation units spanned the Moundville I – late Moundville III phases (A.D. 1120 – 1520).

This geoarchaeological approach, which combined shallow geophysical prospection, macro-and micro-stratigraphic descriptions, as well as archaeological data on ceramic material, supports the hypothesis that Mound Z was an intentionally constructed mound—one of the minor mounds located away from the plaza-periphery core of the site.