Soils and morphology of Carolina bays, Eastern Shore, Virginia

Abstract

Carolina bay landforms were studied on the Eastern Shore of Virginia using aerial infrared imagery provided by the National Aeronautics and Space Administration. Bays were delineated mainly by contrasting soil and vegetation which was enhanced on the imagery and further verified by field investigations.

Typical bay morphology was found in general to be similar to descriptions from other areas. However it was observed that many bays in the study area were more nearly round, and had a more westerly orientation. Consistent strongly developed southeastern rims were not observed as have been reported from other areas.

Bays were determined to be non-randomly distributed within the study area. The majority occur along the central backbone of the peninsula in a generally linear fashion and are apparently associated with larger less distinct depressions. The restriction of bay size by associated land surface may be evidenced by a number of small bays occurring on the narrow peninsula south of Wachapreague and the lack of large bays (over 2 miles in length) in the study area.

Truncation of bays above elevations of 7 ft. by a Pleistocene scarp indicated that they were older than bays occurring at lower elevations near sea level. Examination of bay soils below the scarp also suggested a younger age than those above the scarp as evidenced by lighter textures, thinner solum depths and paler colors. Clay mineralogical determinations also revealed that soils of bays below the scarp were less weathered as evidenced by less gibbsite and greater amounts of weatherable minerals in subsurface horizons.

All soils examined had sandy subsurface horizons indicating a sandy environment of bay formation. Size distribution of sandy fractions revealed that differential sorting probably occurred between bay rims and depressions.