2008 Joint Meeting of The Geological Society of America, Soil Science Society of America, American Society of Agronomy, Crop Science Society of America, Gulf Coast Association of Geological Societies with the Gulf Coast Section of SEPM

Paper No. 11
Presentation Time: 4:20 PM

Late Pliocene (?) Landforms in the Subsurface, Sussex County Delaware

STEPHENS Jr, William E., Stephens Environmental Consulting, Inc, 11 Ailsa Court, Rising Sun, MD 21911 and LOSCO, Russell, West Grove, PA 19390, bstephens@stephensenv.com

Site specific detailed soil and hydrogeologic studies coupled with precise surveying permit the identification and mapping of an ancient land surface in the subsurface at a site in Sussex County, Delaware. Detailed mapping included test pits to 12 feet below grade, Geoprobe probe-holes to 40 feet and hand auger borings on a 75' grid. Investigators were able to differentiate this land surface based on characteristics that included: increased stiffness/density (difficulty, advancing the auger); change to reddish from yellowish hues, evidence of induration, cementation, and deep chemical weathering of lithic and feldspathic grains, relict fluvial versus aeolian sedimentary structures, secondary structures associated with permafrost, and fossil roots and animal burrows. As observed in the test pits, partially lignitized roots, roots channels, animal burrows and secondary sedimentary structures associated with sub-aerial exposure and soil forming processes truncate abruptly at the contact between this surface and the overlying massive, loose aeolian sand.

The Paleosol is interpreted to have formed in fluvial beds of the Beaverdam Formation during a lengthy period a sub-aerial exposure. Primary sedmentiary structures, including graded beds, cross bedding and pebbly horizons can be recognized, with some difficulty, in this Paleosol. Topography and secondary sedimentary structure exert considerable influence on drainage through this paleosol.