4. Geology of the Survey Area. 



a. Regional Stratigraphy and Geologic History. Peninsular Florida is underlain by thick 

 sedimentary rock sequences of Tertiary and Quaternary age; tlie oldest of the exposed rocks 

 belongs to the Eocene-Ocala Group. (See Table 1.) In coastal Brevard County, the Ocala 

 Group lies between —160 to —200 feet MLW and dips southward and eastward to —380 feet 

 MLW along the southern line of Brevard County and to —600 feet MLW in Indian River 

 County. (Brown, et al., 1962.) Overlying the Eocene rocks is a thick section of Miocene, 

 Pleistocene and Holocene marine clays, silts, sands, and shell deposits. Formation names, 

 relative ages and surface occurrences have been compiled by Puri and Vernon (1964), for 

 the entire state and is a useful guide to major rock types and locations. 



Table 1. Stratigraphic Column; Upper Eocene to Recent: Atlantic Central Florida 



Age 



Group 



Formation 



Depth to Top of Formation* 

 Brevard and Indian River Counties 



Age 

 (yrs. ea.) 



Holocene 







to 30 



11 X 10^ 



1 X 10^ 

 10 X 10^ 



25 X 10* 

 40 X 10* 



60 X 10* 



Pleistocene 





Pamhco 



Around + 30 



Anastasia 







Caloosaliatchee 



May occur locally 



Pliocene 









Miocene 





Tamiami 



60 to 230 



Hawthorn 



100 to 400 



Ohgocene 





Suwanee 



Around 400 



Eocene 



Ocala 



Crystal River 



160 to 600 



Williston 





Ingles 













*In feet below MSL 



Modified from Meisburger and Duane (1971) 



A detailed summary of pre-Pleistocene formations of central Florida coastal counties has 

 been presented by Meisburger and Duane (1971). Supporting evidence for their summary of 

 the subsurface geology of Brevard County (based on the work of Brown, et al., 1962) has 

 been obtained from core borings on Cape Canaveral collected by the U.S. Army, Corps of 

 Engineers, Jacksonville District. The boring logs detail depth and nature of the major 

 formations in that area, and agree with results presented by Brown, et al., (1962). An 

 ICONS study (in progress) of northern Florida wiU describe the subsurface geology of that 

 region. 



Significant aspects of Brevard County subsurface geology are summarized as follows: 

 Eocene strata lie beneath Cape Canaveral at about —210 feet MLW; Oligocene rocks are 

 absent from the region; Miocene marine phosphatic clays and sands dipping eastward at a 

 low angle He at about —50 feet MLW, and above this depth upper Miocene or Pliocene 

 unconsolidated sediments rest on a lower Miocene surface (Hawthorn Formation). Also, 

 there is no clear evidence of major faulting in Brevard County subsequent to the close of the 

 Eocene. 



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