due to a scarcity of outcrops. Major structural features occur near the Georgia border and in 

 the vicinity of Daytona Beach. Eocene rocks underlying the coast are principally Umestones. 

 Overlying the Eocene rocks are clastic sediments of heterogeneous lithologic character 

 representing deposits of Miocene, Phocene-Pleistocene and Holocene ages. The principal 

 artesian aquifer of Florida is largely contained in the permeable Eocene limestones and 

 confined by relatively impermeable Miocene strata. 



Beneath the inner shelf floor seismic reflection, profiles show reflectors as deep as —450 

 feet MLW. Based on primary and secondary reflector patterns the visible section was divided 

 into five reflection units. In the lower part of the section witli the two lowermost reflection 

 units, reflectors indicate that the strata are mutually parallel or nearly so. Dip is northward 

 in the northern third of tlie study area and east to soutlieast elsewhere. In the upper section 

 primary reflectors dip gently eastward throughout the study area. Numerous secondary 

 reflectors indicate that upper section strata contain internal bedding features and are 

 apparentiy more heterogeneous and complex than in the lower section. Filled channels 

 incised into the upper section strata are common, especially in the north. 



A broad structural high affecting the lower stratigraphic section is centered off Daytona 

 Beach where the crest of the high has been truncated by erosion. Broad gentle undulations 

 and occasional sharp folding can be seen in both lower and upper section strata throughout 

 the study area. Five widespread subbottom reflectors are judged to be erosional surfaces 

 because they truncate internal bedding and structural features, and are time transgressive. 

 These surfaces record episodes of lower relative sea level or subsidence occurring from 

 probable late Eocene to Pleistocene time. Two of these surfaces can be traced throughout 

 the study area. 



Correlation of the five reflection units underlying the inner shelf with sparse coastal well 

 data indicates that the lowest unit is probably the subsea extension of the Floridan aquifer 

 and is comprised largely of Ocala Group Umestones. The three units overlying the lowermost 

 unit are believed to be of Miocene age. On the basis of core data the uppermost unit is 

 considered to be composed of various beds, lenses, erosional remnants, and channel fill of 

 Pliocene, Pleistocene, and Holocene ages. 



Cores penetrating up to 15.5 feet into shallow subbottom strata show that the shelf is 

 covered by thinly bedded sediments ranging in age from late Tertiary to Holocene. The 

 older relict sediments are exposed at the surface where younger layers have been eroded. 

 These sediments are predominantly quartz sands; silt and clay are common in places but are 

 minor hthologies in the regional context. Most of the sediments encountered are classifiable 

 into five broadly defined lithologic types. These lithologics can be related to the 

 morphology and structure of the inner shelf. 



The shoreface zone contains a fine to very fine quartz sand. Seaward of the shoreface the 

 inner shelf is mantled by a fine to medium (0.125 to 0.5 millimeters; 2 to 1 phi), well-sorted 

 sand that is well suited for use in beach restoration and nourishment. The sand is 



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