AEOLIAN AND FLUVIAL INTERACTION IN THE MIDDLE OHIO RIVER VALLEY: NEW GEOMORPHIC, STRATIGRAPHIC, AND SEDIMENTOLOGICAL EVIDENCE FROM SANDY SPRINGS, ADAMS COUNTY, OHIO

Aeolian landforms in alluvial settings represent a distinct landscape often constructed through a complex interplay of Aeolian, lacustrine, fluvial, and glacial processes. Geomorphological interest in such settings has increased in the humid Eastern U.S. where recent work has studied landscape evolution histories to reconstruct past environments. Sandy Springs is a broad, valley-bottom, landscape of the Ohio River near Vanceburg, Kentucky. Sandy Springs contains three geomorphic surfaces (S1–S3) above a modern floodplain (S0). The lowest surface (S1) contains pronounced ridge-and-swale topography. A broad, sloping, mid-level surface (S2) contains low-relief ridge-and-swale topography and a hummocky terrain that represents relict sand dunes. The highest surface (S3) is discontinuous in distribution, gently sloping, and deeply incised.

The Kentucky Geological Survey (KGS) has mapped the S2 hummocky terrain and S3 surface as sand- and silt-dominated Aeolian deposits. Ongoing geoarchaeological work at Sandy Springs is generating new geomorphic, stratigraphic, and sedimentological data and provides opportunity to re-evaluate initial KGS interpretations. Key to this re-evaluation is the definition of six informal lithostratigraphic units (Aeolian-sand, Aeolian-silt, Aeolian-colluvium, Ohio River alluvium fine-grained, Ohio River alluvium swale, and tributary alluvium) through field inspection and Principal Components Analysis of particle-size parameters. The following preliminary findings are advanced. First, true Aeolian-derived sand dunes exist in the eastern section of the S2 hummocky area. This includes a compound barchan dune, a sand sheet, a complex linear dune, and a potential climbing dune. Second, sandy deposits on the western end of the S2 surface, initially mapped as Aeolian by KGS, represent a thin (<1 m) sand deposit that mantles a pre-existing alluvial terrace ridge. Sedimentological data also suggest a fluvial origin for most of these sediments, perhaps reflecting a relict levee landform. Evidence for minor Aeolian reworking of eastern S2 sediments was documented. Finally, the S3 surface consists of fluvial overbank, not Aeolian, sediments. A noticeable peak in 4-6 φ sediments, however, suggests some amount of loess deposition for sections of the S3 surface.