Abstract: High-level Plio-Pleistocene Shoreline in South Florida

William F. Tanner, M. Hajishafie

A sharply defined wave-cut scarp and platform, between the towns of Sebring and Venus, Florida, in the southern part of the state, records a late Cenozoic high stand of mean sea level. The scarp faces east, and hence was shaped by Atlantic wave activity. Local relief on the scarp is commonly in the 5 to 15-m range. The wave-cut platform, to the east, slopes eastward at about 1.3 m/km, and a dune field 4 or 5 km wide lies to the west. The scarp has been warped and perhaps faulted, with a north-south variation in elevation of the toe. If the main bifurcation in the scarp was the result of faulting, the west side moved up relative to the east side.

Granulometric analysis of sand samples shows mostly eolian activity, but also reasonably clear evidence of high-energy surf.

North of Sebring, the scarp can be traced to a position west of Orlando, where it is much less distinct. The upland west and southwest of Orlando is marked by a beach ridgelike pattern, clearly visible on false-color satellite imagery of Florida. Each ridge appears to be a coalesced set of beach ridges which are no longer individually distinguishable.

The upland ridges are tentatively assigned a Miocene-Pliocene age, and the scarp is thought to have formed in late Pliocene or perhaps earliest Pleistocene time. The inferred faulting would have been Pleistocene in age. The scarp is here named "the Highlands scarp," after Highlands County, where Sebring and Venus are located.

AAPG Search and Discovery Article #90965©1978 GCAGS and GC Section SEPM, New Orleans, Louisiana