COMPARISON OF GRAIN SIZE ANALYSIS TECHNIQUES FOR CLASSIFICATION OF RIM SANDS FROM THE JONES LAKE CAROLINA BAY

Grain size analysis is essential to the understanding of grain size distribution and interpretation of sedimentary environments. This phase of our research is focused on describing the grain size characteristics of Carolina Bay rim sands from Jones Lake in Bladen County North Carolina and comparing four techniques for assessing variations of their textural characteristics. Jones Lake is a prominent Carolina Bay that continues to support a bay lake near its center. Rim sands are most pervasive along the eastern margin and have been sculpted by lacustrine and eolian processes. Three pits were excavated within the eastern rim of the Jones Lake Carolina Bay, which lies within the Bladen Lakes State Forest. Samples were collected at regular intervals from each pit and splits were taken for grain size determination by each of the following procedures: 1) standard sieve analysis at 1 f interval as agitated by hand; 2) standard sieve analysis at .5 f interval as agitated by a sieve shaker; 3) unprocessed sample splits were analyzed using a Beckman Coulter Counter System; and 4) reanalysis using the Beckman Coulter Counter System after the sample splits were processed using a bleach bath to remove organic materials. Raw data were processed using GRADISTAT, which rapidly calculates grain size statistics using Folk and Ward graphical methods. A comparison of results allows us to determine protocol for grain size assessment of rim sands in the Jones Lake Carolina Bay study area and, possibly, most Carolina Bays within the region.