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

likely initiated during times of lower sea level (Tanner, 1991). Increased wave action leads to
the transport of both fine and coarse-grained sediment, which is then deposited as a ridge at the
shoreline. A rise in sea level will flood the landward side of the ridge and isolate it, thus, turning
it into a barrier island.
There have been few studies of barrier island evolution along the Panhandle coast. Rizk
(1991), Tanner (1987) and Forrest (2003) have studied the St. Joseph Peninsula, a barrier spit
located on the Panhandle coast. Stapor (1973) and Tanner (1988, 1990) studied St. Vincent
Island, a barrier island also located on the Panhandle coast.
Beach Ridge Formation
Many late Holocene coastal regions are progradational and are marked by beach ridge
plains. Well-developed beach ridge plains can contain up to 200 individual beach ridges
(Tanner, 1988). The term “beach ridge” has been defined in many different ways. Stapor
(1975) defines beach ridges as linear sand bodies that parallel the modern coast. Otvos (2000)
defines them as relict, semi-parallel, multiple wave- and wind-built landforms that originate in
the intertidal and supratidal zones. Tanner (1995) identified four main categories of beach
ridges. Swash built ridges and settling-lag ridges are long, low to almost invisible and more or
less parallel. They usually occur in sets. The two ridge types can be distinguished from each
other based on their internal structure. Swash built ridges display low-angle cross-bedding while
settling-lag ridges have internal bedding that is horizontal, discontinuous and usually poorly
defined. These two types can be distinguished by trenching or sample analysis. Storm surge
ridges are usually single, isolated features, 5-10 m in height. They do not make up beach ridge
sets or systems. The fourth type of ridge is the dune ridge. Dune ridges are distinguished from
other ridge types on the basis of their internal structure, which is characterized by internal cross-
bedding and hummocky cross-stratification. Dune ridges can be found within or adjacent to a
system of swash or settling lag ridges.
Beach ridge systems are made up of multiple parallel ridges and swales, but usually lack
well-developed lagoons or marshes (Boggs, 1995). A popular idea is that beach ridges within a
set are attached to eachother at a single point. The point of attachment facilitates a determination
of the sand source (Tanner et al., 1989).
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