Recent Submergence of Southern Florida: A Comparison with Adjacent Coasts and Other Eustatic Data
Submergence data gathered in southern Florida indicate that approximately 4400 years ago (in terms of radiocarbon years) sea level was about 4 m lower than today9s level. Between 4400 and 3500 B.P., sea level rose at a rate close to 30 cm/100 years (1.0 foot/century). About 3500 B.P., when sea level stood 1.6 m below its contemporary position, the rate of rise diminished by a factor of five; since 1700 B.P., the rate of rise has averaged only about 3 cm/100 years (0.1 foot/century). Because a considerable body of evidence points to the probable tectonic stability of southern Florida in Recent time, the recorded submergence is regarded as a measure of an eustatic change in sea level. The Florida submergence curve shows that sea level has risen more or less steadily to its present level during the last 4400 years. This differs significantly from the hypothesis that sea level rose 2–4 m above its present position during this time. The Florida submergence data also do not support a strict interpretation of the stable sea-level hypothesis, i.e., that sea level reached its present position (and maintained it) sometime between 3000 and 5000 years ago.