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

Holocene Sea Level
Over 900 Holocene sea-level curves have been published (Dorsey, 1997). The earliest
known examples of Holocene sea-level histories were published in Great Britain using pollen
analyses (Granlund, 1932; Liden, 1938). Approximately 20,000 years ago sea level was 130 m
lower than at present (Stapor and Tanner, 1977). It rose rapidly until about 5,000 to 6,000 years
ago, at which point the rate of rise slowed drastically (Stapor and Tanner, 1977). The history of
sea-level change over the past 5,000 years is much debated. There are two main schools of
thought. The first is that sea level rose steadily from a low position during the Wisconsinan and
approached its present level without significant variations (Kidson, 1982). The second is that
there have been various short-lived sea-level oscillations superimposed on the general rise.
A cooling event between 8,250 and 8,150 years ago was a result of meltwater release into
the North Atlantic (Rohling and Palike, 2005). This stopped North Atlantic Deep Water
(NADW) formation and its associated northward heat transport (Rohling and Palike, 2005).
NADW is a water mass found in the Atlantic at depths between 1,000 and 4,000 m. It can be
traced from there into most other ocean basins. It is formed in the North Atlantic from Atlantic
bottom water entering through the Denmark Strait and across the Scotland-Faeroe-Iceland Ridge.
Water flows towards the Labrador Sea and joins with bottom water from the eastern North
Atlantic. NADW supplies heat and moisture to high northern latitudes and therefore affects the
stability of ice sheets in the northern hemisphere (Lear et al., 2003). The formation of NADW is
one of the most important processes influencing today’s climate (Lear et al., 2003).
The oscillating sea-level curve of Fairbridge (1961) showed a rapid rise in sea level from
the early Holocene to about 6,000 years B.P. after which it fluctuated about current mean sea
level. Shepard (1963, 1964) published a smooth curve that showed sea level rising continuously
to its present level. There have been two periods of rapid and sustained sea-level rise from
16,000-12,500 years ago and from 11,500-8000 years ago (Lambeck and Chappell, 2001). In
general, global sea level has been rising throughout the Holocene- an event termed the
“Holocene Marine Transgression”.
The oscillating model is the most widely accepted model and is believed to accurately
represent how sea level has behaved throughout the mid to late Holocene. For this reason, this
investigation is based on the oscillating model of sea-level change.
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