Loess Deposits of the Eastern Shore of Maryland

Abstract

A silty mantle on the upper Eastern Shore of Maryland was studied to determine its origin and characteristics. Thickness of the silts was studied by selecting traverses in an east‐west direction from the Chesapeake Bay and also scattered borings between traverses. These deposits are believed to be loess; they are characterized by 50 to 75% silt‐sized particles. The material is also carbonatefree, nonstratified, and yellowish brown in color. In addition, the silty mantle shows a reduction in thickness and particle size with increasing distance from the Chesapeake Bay, which was the probable source area. In areas of thin loess (< 90 cm), increasing amounts of sand were apparently incorporated into the loess at the time of deposition. Based on 14C date of a 11A1b horizon of a buried paleosol below the loess, deposition of the silts took place after 10,520 ± 240 years B.P. Profile characteristics of soils developed in the loess show moderately well expressed argillic horizons with the soil in this study having an increase of 9% clay from the A to the B2t horizon or a B2t/A clay ratio of 1.65.

Synthesis on Quaternary aeolian research in the unglaciated eastern United States

“…These soil/parent-material associations have facilitated identification and mapping of both aeolian sand and loess in the unglaciated eastern USA (Wolfe, 1943;Peltier, 1949;Higbee, 1951;Tedrow and MacClintock, 1953;Wright, 1972;Carey et al 1976;Saucier, 1977;Foss et al, 1978;Lindbo et al, 1995;Rhoton et al, 1996;Feldman et al, 2000;Ivester and Leigh, 2003;Markewich et al, 2009a;this study).…”

“…Loess also occurs as small lintels capping interfluves in the Potomac River valley, (Feldman et al, 2000;FL on Fig. 1c in this article) and as interbeds with aeolian sand in raised-rim basins on the Delmarva Peninsula (Foss et al, 1978;Stolt and Rabenhorst, 1987a Hack (1955) first referred to small areas of dunes adjacent to the Potomac and Patuxent Rivers (dune fields A, B, C on Fig. 1c) and in the headwater areas of Coastal Plain streams near Brandywine, MD (BW on Fig.…”

“…1b and d) in New Jersey (NJ), Pennsylvania (PA), Delaware (DE), and Maryland (MD) (Fig. 2b) (Wolfe, 1943;Peltier, 1949;Higbee, 1951;Tedrow and MacClintock, 1953;Wright, 1972;Carey et al 1976;Foss et al, 1978;Rabenhorst et al, 1982;Simonson, 1982;Rebertus et al, 1989;Rebertus, 1998;Lowery, 2002;Wah, 2003;Lowery et al, Fig. 3 (continued) 1 Although relict coastal aeolian sand deposits are present on now-emergent Pleistocene barriers/beach-ridges in the Atlantic Coastal Plain and the Gulf Coastal Plain, we do not include a discussion of these deposits except where the morphologic expression of these coastal deposits has been modified by post-emergent inland aeolian processes.…”

Late Pleistocene upland stratigraphy of the western Delmarva Peninsula, USA

“…1; Walker, 2007;Wah, 2003) and Clovis artifacts at the Cactus Hill site in southern Virginia (Wagner and McAvoy, 2004) C BP (18243 AE 177 cal BP) are younger than the dates obtained from similar stratigraphic units on the Delmarva Peninsula. This second episode of loess deposition covers a larger areal extent than the previous Miles Point Loess (Reybold, 1970;Foss et al, 1978;Wah, 2003). We have designated this regionally recognized silt, commonly associated with modern soil horizons, as the "Paw Paw Loess" based on the original archaeological discovery made at Paw Paw Cove on Tilghman Island.…”

“…Subsequent interpretations, built on these ideas, suggest that the silts were additionally entrained and redeposited by eolian processes during sea level lowstands (e. g., Carey et al, 1976;Owens and Denny, 1979). More recent soil and sedimentological analyses indicate a broader regional expanse of these sediments and support a purely wind blown origin with parent material derived from glacial outwash from the Susquehanna River during and after the Last Glacial Maximum (Reybold, 1970;Foss et al, 1978;Lowery, 2002;Wah, 2003;NRCS, 2009). However, these studies lack the detailed geochronological data necessary to definitively support an eolian source for these upland sediments in the context of Late Pleistocene and Holocene sea level rise (see Nikitina et al, 2000).…”