2006 Philadelphia Annual Meeting (22–25 October 2006)

Paper No. 1
Presentation Time: 8:00 AM-12:00 PM


DIDLAKE, Timothy J., Geoscience, Pennsylvania State University, University Park, PA 16802 and GUERTIN, Laura A., Earth Science, Penn State Delaware County, 25 Yearsley Mill Road, Media, PA 19063, tjd181@psu.edu

Scalloped beaches can result from natural coastal variation as well as from anthropogenic construction. This study examines grain-size distributions and beach profiles for two morphologically similar beach sites in Ocean City, MD: the northern site at 9th Street, where a visible, anthropogenic groin has created a scalloped beach, and the southern site near 1st Street, where a groin is not visible yet a scalloped beach occurs. For both sites, beach elevation profiles were recorded at distances of 10, 25 and 50 feet from both the north and south sides of the groin/scallop headlands. Sediment samples were collected along the 10- and 50-foot profiles from above the high-tide mark, at the high- tide/intertidal boundary, along the intertidal zone and at the intertidal/low-tide boundary. By comparing trends in grain-size distribution and elevation between these two sites, this research compares beach scallops resulting from artificial construction and scallops from natural variation. Because not all groins have been marked on maps or are currently exposed, the possibility that the 1st Street scallops result from a buried groin instead of natural variation is also being considered.

Initial findings have identified similarities and differences between these two scalloped beaches. Profile data indicated that the 9th Street beach has a slightly greater slope than 1st Street. Additionally, the profiles corresponding to similar locations between both sites appeared of the same general shape: concave-up just north, concave-down just south and roughly linear farther from the groin/scallop headlands. Regarding grain-size distribution, nearly all samples from 9th Street were finer than their 1st Street counterparts. At both locations, samples recovered at the high-tide/intertidal boundary were coarser than samples taken closer to the ocean, and nearly all samples from above the high-tide mark had similar grain-size distribution curves, regardless of location. Although preliminary analyses have uncovered indicators suggesting a buried groin at 1st Street, further research is needed to confirm or refute its presence.