permeable Miocene rocks at the base of the section may also be part of 

 the aquifer locally, but stratigraphic details of the system are not well 

 known (Bermes , 1958; Lichtler, 1960; Brown, et al . , 1962). 



(3) Miocene Strata . Overlying Oligocene rocks where present 

 (elsewhere directly on the Eocene) is a thick Miocene section of varie- 

 gated (dark green, brown, and white) phosphatic marine clays, silt, sand 

 and shells. These sediments comprise the Hawthorn Formation and the 

 Tamiami Formation as defined by Parker (1951). Along the coast, the top 

 of Miocene strata lies at approximately -60 feet MLW in the northern part 

 of the study area, and drops to around -200 feet MLW at the south end. 



A discontinuity exists between the top of the Miocene and a time trans - 

 gressive formation below. The pre-Miocene surface in the coastal part 

 of the study area dips southeast about 8 feet or more per mile, while 

 the top of the Miocene dips eastward at a much lower rate. 



(4) Post-Miocene Strata . Miocene sediments under the coastal 

 area are unconformably overlain by Pleistocene sediments of the Anastasia 

 formation, a highly variable series of coquina, sand, and biogenic lime- 

 stone deposits possibly representing depositional episodes throughout 

 Pleistocene time (Puri and Vernon, 1964). The Caloosahatchee marl con- 

 sidered by early workers as Pliocene, but more recently as Pleistocene 



in age (Puri and Vernon, 1964; Du Bar, 1958, 1962), may occur in places 

 as the basal Pleistocene unit. Along the coastal ridge, Anastasia rocks 

 are overlain by quartzose sand of the Pamlico Formation which locally 

 attains a thickness of 40 feet, but is usually much thinner. 



Hoiocene and modem deposits occur on the Continental Shelf, in 

 beaches and dunes of the coastal zone and in lagoons behind the barrier 

 islands. Miocene and Pleistocene rocks are likely contributors to sedi- 

 ments comprising the Holocene littoral system, either at natural or man- 

 made exposures at the coastline or from presumed outcrops on the nearshore 

 Continental Shelf. Pre-Miocene sediments in the study area are too deep 

 to be exposed, and do not contribute directly to the present littoral 

 supply. 



(5) Geologic History . The Eocene and post-Eocene history of 

 the study area is one of repeated invasions and retreats of the sea. 

 Erosional unconformaties and hiatuses in the Eocene column point to 

 tectonic instability throughout that period. A structural movement 

 dated by Vernon (1951) as post-Oligocene and pre-Miocene resulted in the 

 Ocala uplift - centered in western and central Florida - and associated 

 structural flexures and faults affecting a larger part of the central 

 Florida peninsula. A coastal fault or fault zone in pre-Miocene rocks 

 stretching north-northwest through the study area is probably related 



to the Ocala movement. The down thrown blocks on these faults are to 

 the east and plunge southward from a probable hinge line in the northern 

 part of the study area. Seismic reflection records collected for this 

 study show an abrupt steepening of dip of some deep reflections, an appar- 

 ent effect of a near- coast fault between Canaveral Bight and Fort Pierce 

 (Meisburger and Duane, 1969). 



10 



