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Sediment Deposition in Apalachicola Bay, Florida: A 200 Year Chronicle

W. C. Isphording1 and M. E. Bundy2
1Department of Earth Sciences, University of South Alabama, Mobile, AL
2Severn-Trent Laboratories, Mobile, AL

The northern margin of the Gulf of Mexico between the Florida Keys and Brownsville, Texas is fringed with a series of barrier islands and drowned river valleys that have formed 19 major bays and estuaries. These water bodies are of significant economic importance and serve not only as the locations of major seaports (Galveston, Mobile, Tampa, etc.) but are also the nursery areas for important commercial fish and game fish. Hence, any and all events that cause modifications to these sites are viewed closely and the causes must be documented and the magnitude of change assessed.

One such estuary that has received particular study is Apalachicola Bay, Florida. This water body serves as the terminus for the State’s largest stream system and has undergone more documented changes over the past 200 years than any other estuary in the northern Gulf. The causes of the changes are clearly imprinted in its bottom sediments. Deep core samples and radioactive age dating have been used to compile bottom sediment maps for time periods in the early 1800’s and 1900’s. Detailed bottom sediment sampling investigations were subsequently carried out in 1959, 1984, 1986, and 1999. Using the GIS program Arc View, the magnitude and locations of major changes in the types of bottom sediment deposited during these intervals have been mapped and the causes of the changes identified. Hurricanes and the construction of a number of dams along contributory rivers are most responsible for the changes observed.

AAPG Search and Discovery Article #90901©2001 GCAGS, Annual Meeting, Shreveport, Louisiana