T188 Eolian Processes and Landscape Evolution (Posters)

Tuesday, 24 September 2019
9:00 AM - 6:30 PM
Hall AB, North Building

EVIDENCE FOR EOLIAN STRATIGRAPHY AT BURIED ARCHAEOLOGY SITES IN SANDHILLS, NORTH CAROLINA

Paper number: T188-12
Program: Technical Sessions
Time: 9:00 AM – 6:30 PM

Authors

Abstract

Archaeology sites in the Sandhills of North Carolina have evidence of stratified Woodland and Archaic cultural horizons. These sites are located in environments conducive to the accumulation of eolian sediment such as the lee-side of dunes and on sand rims of blowouts. Additionally, these landforms are favorable to occupation as elevated sites that are proximal to a water resource. Archaeological test units show buried cultural horizons to depths of 50 – 60 cm. Sediment samples were collected at 5 – 10 cm spacing to investigate site burial processes. Each sand sample was sieved and grain size statistics were calculated. Twenty five quartz sand grains were imaged from the medium sand fraction on the JEOL JSM-IT300 scanning electron microscope to analyze surface microtextures. Samples were collected from presently active depositional environments including a stream channel, coastal dune, berm and beach face for comparison with the profile samples.

Three stratigraphic units are identified using grain size distribution statistics showing separate populations based on sorting, mean grain size and skewness. In general, the upper stratigraphic units have a finer grain size and are slightly better sorted. Stratum I (0-30 cm) buries the Woodland cultural deposits (1-3 ka BP), stratum II buries (30-60 cm) Archaic deposits (4-10 ka BP). Stratum III ( >60 cm) is interpreted as the Pleistocene Pinehurst Formation. Coarsest 1%, used as a proxy for transport competence, shows an increase in grain size and distinguishes the Pinehurst Formation from younger deposits. OSL dating shows multiple episodes of deposition. Comparisons made between modern environments and sites where archaeology is found demonstrate strong similarities in sorting, skewness and grain micromorphology between dunes and test unit samples. Test unit samples and eolian transported grains from the dunes are generally sub-rounded and exhibit bulbous forms with high relief resulting from irregular depressions caused by multiple mechanical fractures. Conchoidal fractures, v-shaped percussion scars and linear steps are also present throughout.

This stratigraphy shows that cultural deposits of different ages are buried by eolian processes during the Holocene. Therefore, periodic climate conditions supported eolian transport in favorable settings.

Geological Society of America Abstracts with Programs. Vol. 51, No. 5

doi: 10.1130/abs/2019AM-338568

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