Quaternary eolian dunes in the Savannah River Valley, Jasper County, South Carolina, USA

Abstract

Sand hills in the Savannah River valley in Jasper County (South Carolina, USA) are interpreted as the remnants of parabolic eolian dunes composed of sand derived from the Savannah River and stabilized by vegetation under prevailing climate conditions. Optically stimulated luminescence ages reveal that most of the dunes were active ca. 40 to 19 ka ago, coincident with the last glacial maximum (LGM) through early deglaciation. Modern surface winds are not sufficient for sustained eolian sand transport. When the dunes were active, winds blew at velocities of at least 4 m/s from west to east, and some vegetation was present. The ratio of annual precipitation to potential evapotranspiration (P:PE) was less than the modern ratio of 1.23 and may have been < 0.30, caused by stronger winds (which would have resulted in greater evaporation) and/or reduced precipitation. The Savannah River dunes are part of a larger assemblage of eolian dunes that were active in the eastern United States during and immediately after the LGM, suggesting that eolian sediment behavior in this region has been controlled by regional forcing mechanisms during the Quaternary.

Synthesis on Quaternary aeolian research in the unglaciated eastern United States

“…7a, 12a and 13a). In these valleys, dunefield age increases with distance from the modern drainage (Ivester et al, 2001;Swezey et al, 2013;Fig. 7a in this article).…”

“…availability of aerial photographs and satellite imagery, identification and investigation of aeolian sand deposits in the unglaciated eastern USA increased (e.g., Hack, 1955;Hurst et al, 1966a,b;Daniels et al, 1969;Thom, 1970;Otvos, 1971;Pickering and Jones, 1974;Saucier, 1977;Thames, 1982). Continued advancements in radiocarbon, luminescence, and isotopic dating techniques, as well as increased availability of remotely-sensed imagery and high datadensity digital elevation datasets facilitated more-recent geologic, geochronologic, archaeologic, and paleoclimatic investigations of these deposits (Carver and Brook, 1989;Markewich and Markewich, 1994;Leigh and Ivester, 1998;Brooks et al, 2001Brooks et al, , 2010Ivester et al, 2001Ivester et al, , 2002Ivester et al, , 2004aIvester et al, ,b, 2007Ivester et al, , 2009Otvos and Price, 2001;Ivester and Leigh, 2003;Otvos, 2004;Wagner and McAvoy, 2004;Feathers et al, 2006;Markewich et al, 2009aMarkewich et al, ,b, 2010bMarkewich et al, , 2011aMarkewich et al, , 2012Markewich et al, , 2013Lowery et al, 2010;Pavich et al, 2010;Wysocki et al, 2010;Moore and Brooks, 2011;Moore and Daniel, 2011;Swezey et al, 2013;Moore et al, 2014).…”

“…(a) 27-11-ka dunes adjacent on the east to the Savannah River, Jasper County, SC (Schultz et al, 2011;Fig. 2 and Table 1 in Swezey et al, 2013; dunefield area 6 on Figs. 1a, d and 6 in this article): Black arrows indicate paleowind direction.…”

“…1d and 6). ACP dunes primarily consist of medium sand (0.25-0.5 mm) (Thames, 1982;Markewich and Markewich, 1994;Leigh and Ivester, 1998;Ivester and Leigh, 2003;Markewich et al, 2009a,b) or fine (0.125-0.25 mm) and medium sand Swezey et al, 2013). In dune fields along drainages entirely within the ACP, fine sand (0.1-0.25 mm) is dominant .…”

“…They showed that the present-day MAP:MAE ratios of 0.6:1.0 and 0.5:1.0 are similar to those of semiarid and arid regions. Swezey et al (2013) studied late Pleistocene dunes in the Savannah River valley (dunefield area 6 on Figs. 1a, d, and 6 and 9) and suggested that dune formation occurred during climate intervals when MAP:MAE was as low as 0.3.…”