Paper No. 8
Presentation Time: 9:00 AM-6:30 PM


MONAGHAN, G. William, Indiana Gelogical Survey, Indiana University, 611 N. Walnut Grove Ave, Bloomington, IN 47405, WILSON, Jeremy J., Anthropology, Indiana University-Purdue University, Indianapolis, Indianapolis, IN 46202, SWARTZ, Sarah M., Athropology, University of Missouri, Columbia, MO 65211, PIKE, Mathew, Anthropology, Purdue University, West Lafayette, IN 47907, DURBIN, James M., Department of Geology and Physics, University of Southern Indiana, 8600 University Blvd, Evansville, IN 47712, COUNTS, Ronald C., Department of Geology, University of Cincinnati, Cincinnati, OH 45221, HERRMANN, Edward W., Anthropology, Indiana University, 2420 Canada Dr, Bloomington, IN 47401 and THOMPSON, Ashleigh, Athropology, University of Minnesota, Morris, MN 56267,

Angel Mounds (AD 1050-1450) is a late prehistoric town on the Ohio River near Evansville, Indiana, and includes eleven earthen mounds. Chronologies for the largest mounds (A, F) show that they were constructed in stages between AD 1050-1400. A recent NSF-sponsored study at the site provides more details related to mound construction chronologies and methods, and offers new insights about mound use, mound failure/erosion/rebuilding, and late Holocene seismic activity in the midcontinent.

Mound A, studied in 1955, 2008-2010, and 2013, is the largest mound and includes two platforms (upper and lower). The upper platform was built rapidly at ~900 BP by stacking >60,000 m3of overturned turf blocks and basket loads in <10 years. When and how the lower platform was constructed remained unknown until now. Closely spaced, solid-earth cores and geophysical profiles demonstrate that the upper platform was built earlier but underwent significant slumping and sheetwashing on its perimeter before the lower platform was constructed. Additionally, the 2013 work shows that the lower platform was expanded at least twice and also underwent major episodes of erosion and repairs along its perimeter during use and after site abandonment. Forthcoming OSL/AMS ages will provide a detailed chronology for these events.

Mound F, extensively excavated in 1939-42, 1964-65, and 2013, includes two sequentially buried platforms. The initial “Inner Mound” was smaller (~1m high) and built slightly earlier than Mound A. 14C ages show it was in use by ~900 BP. Other 14C ages show that the Inner Mound was buried by a younger, ~2 m high platform (“Primary Mound”) at ~750 BP. Ages from cultural features on its surface suggest it was then buried by ~3-4 m thick fill (“Secondary Mound”) after 530 BP. A profile of Mound F left intact after the 1965 excavations was exhumed during our 2013 NSF-sponsored work and revealed details about the Inner Mound and human activity on the premound ground surface. Additionally, anomalous sand units in the Inner Mound probably represent liquefaction related to a significant earthquake after AD 1100. Forthcoming OSL/AMS ages of the Inner Mound surface and a submound building will improve our understanding of the chronology for premound building activity, initial mound construction, and seismic activity at the site.