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

Hypotheses
Over the course of this investigation, the following hypotheses were tested:
1) Direct luminescence dating of quartz sand grains in beach ridges can provide a high-
resolution history of barrier beach-ridge plain evolution.
2) Beach ridge progradation rates and beach ridge height are influenced primarily by the
rate and direction of sea-level change.
3) Abrupt changes in sea level can have a significant effect on the development of coastal
landforms over a geologically brief span of time.
4) Sea-level history in the northeastern Gulf of Mexico reflects global eustatic history.
5) Beach ridges hold evidence of sea level high stands during the mid- to late- Holocene.
6) Beach ridges are built primarily by swash processes, as opposed to storms.
Regional Geology
The Florida subsurface is a carbonate platform that is approximately 800 km long and
400-720 km wide (Lamont et al., 1997). The State of Florida is the emergent part of the platform
(Randazzo and Jones, 1997). Figure 1.3 shows the carbonate platform. Throughout its history,
the platform has been alternately flooded by shallow seas or exposed as dry land (Randazzo and
Jones, 1997). During times of submergence, 1,200 to 6,100 m of primarily carbonate marine
sediment was deposited on the platform. Following, or concurrent with one of the later periods
of emergence, the plateau tilted about its longitudinal axis. As a result of this, the west coast of
the platform is partially submerged relative to the east coast. Florida’s submergence rate over
the past 4,500 years has averaged 1.2 mm/yr (Scholl, 1969).
The geologic history of Florida has been strongly influenced by sea-level change. The
gentle slope and lack of surface relief on the platform means that a relatively small change in sea
level can have dramatic impacts (Randazzo and Jones, 1997). Changes in sea level can change
3