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GEOREF RECORD

Fair- and foul-weather shell accumulations on a Georgia beach

Robert W. Frey and Juergen Doerjes
Fair- and foul-weather shell accumulations on a Georgia beach
Palaios (1988) 3 (6): 561-576

Abstract

Wrack-line accumulations of beach shells are governed primarily by longshore drift and secondarily by local geomorphic variations along the strand. During low-energy conditions of summer on Sapelo Island beaches, most shells move in the direction of prevalent wave incidence and accumulate in beach re-entrants. Very few shells accumulate on beach protrusions, which are focal points for refracting waves, or on estuary-inlet beaches, where ebb-tidal currents predominate over longshore currents. During high-energy conditions associated with a minor tropical storm, virtually all trends in shell accumulation were reversed. Most shells were removed from the beach; yet more shells remained along relatively straight beach segments than within beach re-entrants, at a point midway between major northward and southward components of longshore drift. These contrasting assemblages thus help demonstrate the importance of comparative taphonomy as (1) a measure of fluctuating coastal conditions--especially the shift from "background" to "episodic" stratinomy--and (2) a prerequisite to paleoecological and paleoenvironmental reconstructions. Most beach shells, storm and nonstorm, were derived originally from the nearshore shelf. Major differences between the structure of nearshore populations and that of beach-shell assemblages, aside from physical stratinomic effects, are attributable to hermit crab utilization of select gastropod valves and to differential rates of productivity among standing crops of mollusks.


ISSN: 0883-1351
Serial Title: Palaios
Serial Volume: 3
Serial Issue: 6
Title: Fair- and foul-weather shell accumulations on a Georgia beach
Affiliation: University of Georgia, Department of Geology, Athens, GA, United States
Pages: 561-576
Published: 1988
Text Language: English
Publisher: Society of Economic Paleontologists and Mineralogists, Tulsa, OK, United States
References: 35
Accession Number: 2006-026664
Categories: Invertebrate paleontology
Document Type: Serial
Bibliographic Level: Analytic
Annotation: Includes appendices
Illustration Description: illus. incl. 3 tables, strat. cols., sketch maps
N31°25'60" - N31°25'60", W81°15'00" - W81°15'00"
Secondary Affiliation: Senckenberg Institut, DEU, Federal Republic of Germany
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2017, American Geosciences Institute. Reference includes data supplied by SEPM (Society for Sedimentary Geology), Tulsa, OK, United States
Update Code: 200614
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