the florida state university college of arts and sciences evolution of ...

first is that sea level rose steadily from a low position in Wisconsin time to its present level
without variations (Tanner et al., 1989). The second is that there have been various short-lived
cycles of sea level, including at least one position 1.0 m above present level 4,000-6,000 years
ago (Tanner et al., 1989). The third is that the noise in the sea-level data is so great that no
meaningful information can be obtained.
The most recent comprehensive Gulf of Mexico sea-level history was presented by
Balsillie and Donoghue (2004). Published and unpublished Pleistocene and Holocene sea-level
data for the northern and eastern Gulf of Mexico coast were collected. All of the data collected
were based on the radiocarbon dating of shoreline indicators. A total of 342 dated sea-level
indicators were assessed, covering the past 20,000 years of geologic time. Each date was
analyzed to determine if it represented a stable (i.e. unaffected by tectonic processes, such as
subsidence) vertical sea-level indicator. Any questionable data were discarded. Figure 1.5 is a
compilation of all available radiocarbon dated sea-level indicators for the northern Gulf of
Mexico. The upper panel of Figure 1.5 reveals that several abrupt sea-level changes of 1 to 2 m
are recorded in the Gulf of Mexico chronology. Such changes occurred at approximately 2,200
years B.P., 4,000 years B.P., 5,400 years B.P. and 6,800 years B.P. There are few details beyond
3,500 years B.P. along the Gulf of Mexico coast because beach ridge history extends only to
approximately 3,500 years B.P. (Tanner, 1991a). The Balsillie and Donoghue (2004) curve is
the most recent and well-defined sea-level curve for the northern Gulf of Mexico.
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