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Apalachicola Bay interpreted seismic horizons and updated IRIS chirp seismic-reflection data

June 11, 2012

Apalachicola Bay and St. George Sound contain the largest oyster fishery in Florida, and the growth and distribution of the numerous oyster reefs here are the combined product of modern estuarine conditions and the late Holocene evolution of the bay. A suite of geophysical data and cores were collected during a cooperative study by the U.S. Geological Survey, the National Oceanic and Atmospheric Administration Coastal Services Center, and the Apalachicola National Estuarine Research Reserve to refine the geology of the bay floor as well as the bay's Holocene stratigraphy. Sidescan-sonar imagery, bathymetry, high-resolution seismic profiles, and cores show that oyster reefs occupy the crests of sandy shoals that range from 1 to 7 kilometers in length, while most of the remainder of the bay floor is covered by mud. The sandy shoals are the surficial expression of broader sand deposits associated with deltas that advanced southward into the bay between 6,400 and 4,400 years before present. The seismic and core data indicate that the extent of oyster reefs was greatest between 2,400 and 1,200 years before present and has decreased since then due to the continued input of mud to the bay by the Apalachicola River. The association of oyster reefs with the middle to late Holocene sandy delta deposits indicates that the present distribution of oyster beds is controlled in part by the geologic evolution of the estuary.

Publication Year 2012
Title Apalachicola Bay interpreted seismic horizons and updated IRIS chirp seismic-reflection data
DOI 10.3133/ofr20121003
Authors V.A. Cross, D. C. Twichell, D. S. Foster, T. F. O'Brien
Publication Type Report
Publication Subtype USGS Numbered Series
Series Title Open-File Report
Series Number 2012-1003
Index ID ofr20121003
Record Source USGS Publications Warehouse
USGS Organization Woods Hole Coastal and Marine Science Center