UNDIFFERENTIATED
OLIGOCENE RESIDUUM
Overlying the Ocala Limestone and its residuum in the Dougherty Plain is a lighter colored residuum which contains abundant fragments of chert, a replacement of the original limestone by silica. The chert occurs in sizes ranging from small pebbles to huge boulders several meters in size. In many fragments the silica replacement has obliterated the original texture, but in a sizeable proportion early Oligocene fossils are preserved.
The original limestone composition and the character of the fossils suggest deposition on an open marine shelf, probably a shelf landward of the 'reefs' of the Bridgeboro Limestone.
Characteristic fossils include:
KINGDOM PROTISTA
PHYLUM PROTOZOA
CLASS SARCODINA
ORDER FORAMINIFERA
KINGDOM ANIMALIA
PHYLUM MOLLUSCA
CLASS BIVALVIA
PHYLUM ECHINODERMATA
CLASS ECHINOIDEA
ORDER CLYPEASTEROIDA
ORDER CASSIDULOIDA