STATE OF FLORIDA

DEPARTMENT OF ENVIRONMENTAL PROTECTION David B. Struhs, Secretary

DIVISION OF RESOURCE ASSESSMENT AND MANAGEMENT Edwin J. Conklin, Director

FLORIDA GEOLOGICAL SURVEY Walter Schmidt, State Geologist and Chief

OPEN-FILE REPORT 80

TEXT TO ACCOMPANY THE

GEOLOGIC MAP OF FLORIDA

By

Thomas M. Scott, P.G. #99

FLORIDA GEOLOGICAL SURVEY Tallahassee, Florida
2001
ISSN 1058-1391FLORIDA GEOLOGICAL SURVEY

1 TEXT TO ACCOMPANY

THE GEOLOGIC MAP OF FLORIDA By Thomas M. Scott, P.G. 99

INTRODUCTION

The Florida Platform lies on the south-centr al part of the North American Plate, extending to the southeast from the North Ameri can continent separating the Gulf of Mexico

from the Atlantic Ocean. The Florida Platfo rm, as measured above the 300 foot (91 meter) isobath, spans more than 350 miles (565 kilometers ) at its greatest width and extends southward more than 450 miles (725 kilometers) at its greates t length. The modern Florida peninsula is the exposed part of the platform and lies predominantly east of the axis of the platform. Most of the State of Florida lies on the Florida Platform; the western panhandle is part of the Gulf Coastal

Plain.

The basement rocks of the Florida Plat form include Precambrian-Cambrian igneous rocks, Ordovician-Devonian sedimentary rocks, and Triassic-Jurassic volcanic rocks (Arthur, 1988). Florida’s igneous and sedimentary foundati on separated from what is now the African Plate when the super-continent Pangea rifted ap art in the Triassic (pre-Middle Jurassic?) and sutured to the North American craton (Smith, 1982). A thick sequence of mid-Jurassic to Holocene sediments (unlithified to well lithified) lies unconformably upon the eroded surface of the basement rocks. Carbonate sedimentation predominated from mid-Jurassic until at least mid- Oligocene on most of the Florida Platform. In response to renewed uplift and erosion in the A ppalachian highlands to the north and sea-level fluctuations, siliciclastic sediments began to encroach upon the carbonate-depositing

environments of the Florida Platform. De position of siliciclastic-bearing carbonates and siliciclastic sediments predominated from mi d-Oligocene to the Holocene over much of the platform. Numerous disconformities that fo rmed in response to nondeposition and erosion resulting from sea-level fluctuations occur within the stratigraphic section. The oldest sediments exposed at the m odern land surface are Middle Eocene carbonates of the Avon Park Formation which crop out on the crest of the Ocala Platform in west-central Florida. The pattern of exposures of younger sediments is obvious on the geologic map. Much of the state is blanketed by Pliocene to Holocene siliciclastic and siliciclastic-bearing sediments that were deposited in response to late Tertiary and Quaternary sea-level fluctuations. The characteristic landscape of Florida is re latively to extremely flat. There are few large, natural exposures and limited smaller exposures that geologists can investigate. The result is that geologists must rely primarily on de-watered or dry pits and quarries for exposures and must make use of subsurface data in studying the geology of Florida. Subsurface data, in the form of well cuttings and cores, were utilized extensively in the development of this map. Formational tops recognized in the subsurface ha ve been extrapolated to the surface where exposures are limited.

PREVIOUS INVESTIGATIONS Previously published geological maps of Fl orida include Smith (1881), Dall and Harris (1892), Matson et al. (1909), Sellards, Gunter and Cooke (1922), Cooke and Mossom (1929), Cooke (1945), Vernon (1951), Vernon a nd Puri (1964) and Brooks (1982).OPEN FILE REPORT NO. 80

2 Groundwork for a new geologic map of Florida began in the 1980s with a county-level mapping effort as part of a statewide radon inve stigation. The county maps created for the radon project were merged and modified to produce a new State map. The geologists from the Florida Geological Survey (FGS) involved in the proj ect included Jon Arthur, Ken Campbell, Joel Duncan, Frank Rupert, and Tom Scott. Tom Mi ssimer, Missimer International, Ft. Myers, Florida was part of the mapping team for Ch arlotte and Lee Counties. Previous mapping provided a basis for this proj ect. Geologists involved in the preliminary mapping included Paulette Bond, Richard Johnson, Ed Lane, Walt Schmidt and Bill Yon.

METHODS Much of Florida is covered by a blanke t of Pliocene to Holocene, undifferentiated siliciclastics that range in thickness from less than one foot to greater than 100 feet. As a result, in developing the criteria for producing this map, FGS geologists decided to map the first recognizable lithostratigraphic unit occurring within 20 feet (6.1 meters) of the land surface. In areas where highly karstic limestones underlie th e undifferentiated siliciclastics, paleosinkholes may be infilled with significantly thicker sequen ces of siliciclastics. If the shallowest

occurrences of the karstic carbonates were 20 fe et (6.1 meters) or less below land surface, the carbonate lithostratigraphic unit was mapped. If the carbonates lie more than 20 feet (6.1 meters) below land surface, an undifferentiated siliciclastic unit was mapped.

Undifferentiated siliciclastic sediments occur in significant thickness (>20 feet [6.1 meters]) over much of the Gulf Coastal Lowlands (White, 1970; Scott, in preparation) and the eastern part of the Florida peninsula. Where th ese sediments were mapped, efforts were made to determine if beach-ridge or dune topography was present in order to subdivide the siliciclastic

sediments. Lithostratigraphic terminology applied in this mapping effort followed, with limited changes, the lithostratigraphic framework delineat ed for the Gulf Coast Region chart from the Correlation of Stratigraphic Units of Nort h America Project (COSUNA) (Braunstein et al

., 1988). Although some of the units depicted on the COSUNA chart have a significant biostratigraphic basis, the COSUNA chart represents the best effort to date to provide an accurate stratigraphic framework for the Florida Platform and surrounding regions. A peer review of the geologic map and this text by members of the geologic community outside the FGS was done by S. Upchurch, R. Port ell, T. Missimer, J. Bryan, J. Vecchioli, A. Tihansky, K. Cunningham, G. L. Barr and R. Spechle r. The FGS greatly appreciates the efforts of these geologists. FGS cartographers Jim Jones and Ted Kiper wo rked on the initial phase of this project. CAD analyst Amy Graves assisted in the map pr eparation. Lou Cross and Peter Krafft from Florida Resources and Environmental Analysis Ce nter, Florida State University, finalized the map in preparation for publication.

STRATIGRAPHIC COLUMN AND CROSS SECTIONS Lithostratigraphic units expressed on the St ate geological map range from Middle Eocene to Holocene. The stratigraphic column showi ng the lithostratigraphic units utilized on the map delineates only the formations occurring at or n ear the surface (Figure 1). Table 1 lists the stratigraphic units and provides a brief lithologic co mponents list. Cross sections (Figures 2 and 3) were constructed utilizing cores and well cuttings from the FGS well cuttings and core repository. By necessity, the cross sections s how some lithostratigraphic units that do not cropFLORIDA GEOLOGICAL SURVEY

3 out. These include the Pensacola Clay, Coarse Clastics, Bruce Creek Limestone, and the Long Key Formation. Table 2 lists information for the wells used in the cross sections.



### Table 1. Stratigraphic units and lithologies.

Unit Lithologies

TERTIARY

Middle Eocene Tap Avon Park Formation limestone, dolostone

Upper Eocene To Ocala Limestone limestone, dolostone

Lower Oligocene

Ts Suwannee Limestone limestone

Tsm Suwannee-Marianna Limestones Undif. limestone

Upper Oligocene to Middle Miocene Tha Hawthorn Group, Arcadia Formation dolostone, limestone, sand, clay, phosphate That Hawthorn Group, Tampa Member limestone, dolostone, sand, clay

Miocene Tsmk St. Marks Formation limestone, sand Tch Chattahoochee Formation dolostone, limestone, sand, clay, Th Hawthorn Group dolostone, limestone, sand, clay, phosphate Tht Hawthorn Group, Torreya Formation clay, sand, limestone Ths Hawthorn Group, Statenville Formation dolostone, sand, clay, phosphate Thc Hawthorn Group, Coosawhatchie Formation sand, clay limestone, dolostone, phosphate Tab Alum Bluff Group clay, sand

Miocene-Pliocene Thp Hawthorn Group, Peace River Formation sand, clay, dolostone, phosphate Thpb Hawthorn Group, Peace River Formation, sand, clay, phosphate, Bone Valley Member dolostone Thcc Hawthorn Group, Coosawhatchie Formation, clay, sand, limestone

Charlton MemberOPEN FILE REPORT NO. 80

4 TABLE 1 (CONTINUED)

TERTIARY/QUATERNARY

Unit Lithologies

Pliocene Tt Tamiami Formation limestone, sand, clay Tjb Jackson Bluff Formation clay, sand Tic Intracoastal Formation limestone, sand, clay Tmc Miccosukee Formation sand, clay Tci Citronelle Formation sand, clay Tc Cypresshead Formation sand, clay TQuc Reworked Cypresshead Formation sand, clay TQd Dunes sand TQu Undifferentiated sediments sand, clay TQsu Shell-bearing sediments shells, sand, clay

QUATERNARY

Pleistocene Qtr Trail Ridge sands sand, heavy minerals Qm Miami Limestone limestone, sand Qk Key Largo Limestone limestone Qa Anastasia Formation limestone, coquina, sand

Pleistocene/Holocene Qu Undifferentiated sand, clay, organics Qbd Beach Ridge and Dune sand Qal Alluvium sand, clay, organics

Holocene Qh Holocene sediments sand, clay, organicsFLORIDA GEOLOGICAL SURVEY

5 

### Table 2. Wells used in cross sections.

W # County Section Town

ship Range Elevation

(msl) Composite

with W# Cross Section

& Well #

148 Walton 12 1N 19W 200 7951 4 A-A'

275 Lake se/se 17 24S 25E 113 5 B-B'

935 Dade sw/sw 31 53S 35E 18 9 B-B'

1345 Okaloosa sw/ne 1 3N 25W 189 3 A-A'

1465 Alachua ne/se/sw 23 8S 18E 102 3 B-B'

1482 Marion sw/nw 16 16S 23E 74 4 B-B'

1596 Madison sw/se 6 1S 10E 107 15803 9 A-A'

1610 Calhoun nw/se 31 2N 9W 217 11270 6 A-A'

1754 Polk sw/sw 18 30S 28E 147 6 B-B'
1758 Washington sw/sw 31 2N 13W 125 10954 5 A-A'

1768 Gadsden ne/nw 35 2N 3W 200 15795 7 A-A'

1789 Columbia se 22 1N 17E 129 1 B-B'

1832 Columbia ne/ne 24 2S 16E 138 15162 10 A-A' 2 B-B'

1854 Jefferson 1 2S 3E 51 6931 8 A-A'

3455 Santa Rosa ne/ne 10 2N 27W 35 2 A-A'

4597 Escambia nw/nw 2 1N 31W 110 1 A-A'

6931 Jefferson se/ne 29 1S 4E 200 1854 8 A-A'

7971 Walton se/sw 9 1N 18W 195 148 4 A-A'

8736 Duval ne/ne 23 1S 24E 82 8881 11 A-A'

8881 Duval ne/ne 23 1S 24E 81 8736 11 A-A'
10954 Washington ne 16 1N 14W 125 1758 5 A-A'

11270 Calhoun nw/ne 13 1N 10W 125 1610 6 A-A'

15162 Columbia se/sw 23 2S 17E 140 1832 2 B-B'
15644 Highlands 17 37S 30E 104 7 B-B'

15795 Gadsden ne/ne 6 1N 2W 200 1768 7 A-A'

15803 Madison ne/se 34 1N 9E 161 1596 9 A-A'
16058 Hendry se/sw 27 45S 34E 18 8 B-B'

17156 Monroe sw 26 64S 35E 1 11 B-B'

17273 Dade sw 36 58S 36E 5 10 B-B'

ODAW#1 Duval 4 2S 29E 15 12 A-A'OPEN FILE REPORT NO. 80

6 Figure 1. Stratigraphic column showing the lithostratigraphic units used on the map.FLORIDA GEOLOGICAL SURVEY

7 Figure 2. Geological cross section locations.OPEN FILE REPORT NO. 80

8Figure 3. Geologic cross sections.FLORIDA GEOLOGICAL SURVEY

9 Figure 4. Geologic structures in Florida (modified from Scott, 1988).OPEN FILE REPORT NO. 80

10 GEOLOGIC STRUCTURES The geologic structures (Fi gure 4) that have affected shallow Tertiary and Quaternary

sediments of the Florida Platform have been defined by numerous au thors (Puri and Vernon, 1964; Miller, 1986; Scott, 1988; Scott, 1991). The majority of the structures recognized as influencing the deposition, erosion and alteration of the Cenozoic sediments in Florida do not appear to have had a significant effect on the surface expression of the lithostratigraphic units. These geologic structures include the Gulf Basin, Jacksonville Basin, St. Johns Platform, Sanford High, Brevard Platform, Osceola Low and the Okeechobee Basin (Scott, 1992). Those

structural features that exerted an influence on the surficial or very near surface distribution of the Cenozoic sediments, or mark areas of si gnificant facies changes, include the Gulf Trough/Apalachicola Embayment, Chattahoochee “Anticline” and the Ocala Platform. Eocene sediments crop out on the Chattahoochee Anticline and the Ocala Platform. The Gulf Trough/ Apalachicola Embayment formed an important ba thymetric and environmental barrier from the latest Eocene or earliest Oligocene into the Miocen e. As a result, the Oligocene carbonate facies east and south of the Gulf Trough/Apalachicola Em bayment are distinctly different from those occurring to the west and north (see Schmidt [1984] and Bryan [1991] for discussion).

LITHOSTRATIGRAPHIC UNITS

TERTIARY SYSTEM

Eocene Series Middle Eocene - Bartonian Stage

Tap - Avon Park Formation - Middle Eocene carbona te sediments of peninsular Florida, as originally described by Applin and Applin (1944), were subdivided, in ascending order, into the Lake City Limestone and the Avon Park Limestone. Miller (1986) recommended combining the Lake City Limestone with the Avon Park Limestone and, due to the common occurrence of dolostone, referred to the unit as the Avon Park Formation. Carbonates of the Avon Park Formation are the oldest sediments exposed in th e state. The Avon Park Formation crops out in a limited area in west-central peninsular Florida in Levy and Citrus Counties on the crest of the

Ocala Platform.

The Avon Park Formation consists of cream to light-brown or tan, poorly indurated to well indurated, variably fossiliferous, limestone (grainstone, packstone and wackestone, with rare mudstone). These limestones are interbedde d with tan to brown, very poorly indurated to well indurated, very fine to medium crys talline, fossiliferous (molds and casts), vuggy dolostones. The fossils present include mollusks, foraminifers, echinoids, algae and carbonized plant remains. Molds and casts of gypsum crystals occur locally. The Avon Park Formation is part of the Flor idan aquifer system (FAS). Parts of the Avon Park Formation comprise important, subreg ional confining units within the FAS (Miller, 1986).FLORIDA GEOLOGICAL SURVEY

11 Upper Eocene - Priabonian Stage

To - Ocala Limestone - Dall and Harris (1892) referred to the limestones exposed near Ocala, Marion County, in central peninsular Fl orida as the Ocala Limestone. Puri (1953, 1957) elevated the Ocala Limestone to group status r ecognizing its component formations on the basis of foraminiferal faunas (biozones). Scott (1991) reduced the Ocala Group to formational status

in accordance with the North American Stra tigraphic Code (North American Commission on Stratigraphic Nomenclature, 1983). The Ocala Limestone consists of nearly pure limestones and occasional dolostones. It can be subdivided into lower and upper facies on the basis of lithology. The lower member is composed of a white to cream-colored, fine to medium grained, poorly to moderately indurated, very fossiliferous limestone (grainstone and pack stone). The lower facies may not be present throughout the areal extent of the Ocala Lime stone and may be partially to completely dolomitized in some regions (Miller, 1986). The upper facies is a white, poorly to well indurated, poorly sorted, very fossiliferous limest one (grainstone, packstone and wackestone). Silicified limestone (chert) is common in the upper facies. Fossils present in the Ocala Limestone include abundant large and smaller fora minifers, echinoids, bryozoans and mollusks. The large foraminifera Lepidocyclina sp

. is abundant in the upper faci es and extremely limited in the lower facies. The presence of these large forami nifers in the upper facies is quite distinctive.

The Ocala Limestone is at or near the surface within the Ocala Karst District in the westcentral to northwestern peninsula and within th e Dougherty Plain District in the north-central panhandle (Scott, in preparation). In these areas, the Ocala Limestone exhibits extensive

karstification. These karst features often have te ns of feet (meters) of relief, dramatically influencing the topography of the Ocala Karst Distri ct and the Dougherty Plain District (Scott, in preparation). Numerous disappearing streams and springs occur within these areas. The permeable, highly transmissive carbonates of the Ocala Limestone form an important part of the FAS. It is one of the most permeable rock units in the FAS (Miller, 1986).

Tre - Residuum on Eocene sediments - The post-Eocene residuum lying on Eocene sediments in the panhandle consists of reddi sh brown, sandy clays and clayey sands with

inclusions of weathered Eocene limestones. Some of the inclusions are silicified carbonates.

Oligocene Series Lower Oligocene - Rupelian Stage

Previous geologic maps of Florida presente d the Lower Oligocene sediments exposed at

the surface or in the shallow subsurface in a variety of ways. Cooke (1945) mapped, in ascending order, the Marianna Limestone, Byra m Formation, Suwannee Limestone and the Flint River Formation. Vernon and Puri (1964) id entified the Marianna Limestone, “Byram” Formation, Duncan Church beds and the Suwa nnee Limestone. Brooks (1982) recognized the Marianna Limestone, Suwannee Limestone and th e Duncan Church facies of the Suwannee Limestone. The variations in the stratigraphic units are indicative of the confusion over the lithologic recognition and subdivision of the Lower Oligocene sediments. The confusion is at least partially due to the use of biostratigraphic data to subdivide the lithostratigraphic units.OPEN FILE REPORT NO. 80

12 Huddlestun (1993) recognized a tripartite s ubdivision in the type area of the Suwannee Limestone in northwestern peninsular Flor ida and proposed the Ellaville Limestone,

Suwannacoochee Dolostone and Suwannee Limestone . In the panhandle, west of the Gulf Trough, Huddlestun (1993) recognized the Mari anna Limestone and an undifferentiated residuum as the Oligocene sediments extending into Florida’s panhandle from Georgia. Huddlestun (1993) also recognized Bucatunna Formation, Florala Limestone, Bridgeboro

Limestone and an unnamed marl in Okaloosa and Walton Counties. Bryan (1991, 1993) provides a better framework for the recognition of the various facies within the Lower Oligocene sediments. With in this framework, the Ellaville Limestone,

Suwannacoochee Dolostone and Suwannee Limest one occur within his Florida Platform Association east and south of the Gulf Trough. West of the Gulf Trough in the Florida panhandle (Bryan’s Eastern Gulf Shelf Associ ation), Bryan (1991) recognized the Bumpnose Limestone, Marianna Limestone, Bridgebor o Limestone, Florala Limestone, Suwannee Limestone, Byram Marl and Bucatunna Formation. The limited data available, the occurrence of thin beds of some of these units and the questionable occurrence of other units made mapping the Lower Oligocene sediments in the central panhandle problematic. The approach se lected by FGS geologists was to combine the units into several mappable units appropriate fo r the scale of the present map. These mappable units include: undifferentiated Oligocene sedi ments composed of the Bumpnose Limestone, Marianna Limestone, Bridgeboro Limestone, Flor ala Limestone, Suwannee Limestone, thin beds of the Byram Marl and Bucatunna Formation and undifferentiated Oligocene residuum (see Huddlestun [1993] for a discussion of the origin of the residuum). The Lower Oligocene sediments of penins ular Florida are mapped as the Suwannee

Limestone and are not subdivided into the Ella ville Limestone, Suwannacoochee Dolostone and Suwannee Limestone. This mapping convention was adopted by FGS geologists due to the

limited data on the areal distribution of the Ellaville Limestone and Suwannacoochee Dolostone.

Ts - Suwannee Limestone - Peninsular Lo wer Oligocene carbonates crop out on the northwestern, northeastern and southwestern fl anks of the Ocala Platform. The Suwannee

Limestone is absent from the eastern side of the Ocala Platform due to erosion, nondeposition or both, an area referred to as Orange Island (Bryan, 1991). The Suwannee Limestone, originally named by Cooke and Mansfield (1936), consists of a white to cream, poorly to well indurated, foss iliferous, vuggy to moldic limestone (grainstone and packstone). The dolomitized parts of the Su wannee Limestone are gray, tan, light brown to moderate brown, moderately to well indurated, fi nely to coarsely crystalline, dolostone with limited occurrences of fossiliferous (molds and cas ts) beds. Silicified limestone is common in Suwannee Limestone. Fossils present in the Suwannee Limestone include mollusks, foraminifers, corals and echinoids.

Tsm - Undifferentiated Lower Oligocene Sediments - The undifferentiated Lower Oligocene sediments of the central panhandle cons ist of white to cream-colored, poorly to well indurated, variably fossiliferous limestones (grain stone, packstone, wackestone and mudstone). Glauconite occurs in some sediments. Siliciclastics form a minor component in some sediments. Thin beds of siliciclastics (Byram Marl and Buccatuna Formation) are included in theFLORIDA GEOLOGICAL SURVEY

13 undifferentiated Lower Oligocene sediments. The Lower Oligocene carbonates form important parts of the upper FAS (Miller, 1986).

Tro - Residuum on Oligocene sediments - The undifferentiated Oligocene residuum, mapped on parts of the Chattahoochee “Anticline”, characteristically consists of reddish brown, variably sandy clay with inclusions of variab ly fossiliferous, silicified limestone (Huddlestun, 1993). The residuum includes Lower and Upper Oligocene weathered sediments (Huddlestun, 1993).

Oligocene - Miocene Series Upper Oligocene - Middle Miocene - Chattian - Serravalian Stage

PENINSULA

Lower Hawthorn Group Recent investigations into the Oligocene of southern Florida documented the existence of a thick (>330 feet [100 meters]) Upper Oligocene section previously considered Miocene (Scott

et al ., 1994; Missimer and Scott, 1995; Brewster-Wingard et al ., 1997). The Arcadia Formation, Hawthorn Group, previously thought to be predom inantly Early Miocene (Scott, 1988), is now known to be late Early Oligocene to Middle Miocene (Brewster-Wingard et al ., 1997; Missimer, 1997). The Tampa Limestone (or Formation of previous usage [Puri and Vernon, 1964]) is a member of the Arcadia Formation, Hawthorn Group (Scott, 1988). The Tampa Member’s previous age assignment was latest Oligocen e to Early Miocene (Scott, 1988). BrewsterWingard et al . (1997) recognized the Tampa Member as being Late Oligocene to Early Miocene.

Tha - Hawthorn Group, Arcadia Formation - The undifferentiated Arcadia Formation and the Tampa Member crop out on the southweste rn flank of the Ocala Platform from Pasco County southward to Sarasota County. Although ages of the outcropping sediments have not been accurately determined, stratigraphic position s uggests that the Upper Oligocene parts of the Arcadia Formation and Tampa Member are e xposed in this region, particularly from Hillsborough County northward to Pasco County. The Arcadia Formation, named by Scott (1988) , is predominantly a carbonate unit with a variable siliciclastic component, including thin be ds of siliciclastics. Within the outcrop area, the Arcadia Formation, with the exception of the Tampa Member, is composed of yellowish gray to light olive gray to light brown, micro to finely crystalline, variably sandy, clayey, and phosphatic, fossiliferous limestones and dolostones. Thin beds of sand and clay are common. The sands are yellowish gray, very fine to me dium grained, poorly to moderately indurated, clayey, dolomitic and phosphatic. The clays are yellowish gray to light olive gray, poorly to moderately indurated, sandy, silty, phosphatic and dolomitic. Molds and casts of mollusks are

common in the dolostones. Silicified carbonates and opalized claystone are found in the Arcadia

Formation.

That - Arcadia Formation, Tampa Member - The Tampa Member consists predominantly of limestone with subordinate dolostone, sa nd and clay (Scott, 1988). The lithology of the Tampa Member is very similar to that of the s ubsurface limestone part of the Arcadia FormationOPEN FILE REPORT NO. 80

14 except that the Tampa Member contains noticeab ly less phosphate (Scott, 1988). The limestone in the Tampa is white to yellowish gray, fossiliferous and variably sandy and clayey mudstone, wackestone and packstone with minor to no phospha te grains. Sand and clay beds are like those

in the undifferentiated Arcadia Formation. Mo llusks and corals are common in the Tampa Member as molds and casts, silicified pseudomor phs and original shell material. The Tampa Member and the lower part of the Arcadia Forma tion form the upper part of the Floridan aquifer system (FAS) in parts of southern Florida (Miller, 1986; Scott, 1991).

PANHANDLE

Upper Oligocene sediments are not known to crop out in the Florida panhandle. The Chickasawhay Formation of Alabama has been traced in the subsurface into the central panhandle but is not exposed on the Chattahoochee Anticline (Miller, 1986).

Miocene Series Lower Miocene to Upper Miocene - Aquitanian to Messinian Stage

Sediments of the Miocene Series have been the focus of numerous investigations due to their complex nature and widespread occurre nce in Florida (see Schmidt and Clark [1980], Huddlestun [1988] and Scott [1988] for a review of previous investigations). The Miocene sediments consist of siliciclastics, carbonates and mixed siliciclastic-carbonate lithologies with numerous lateral and vertical facies changes. Exposures are limited and most investigations

dealt with these sediments in the subsurface. Miocene sediments crop out or occur in th e shallow subsurface on the northwestern flank

of the Ocala Platform in the eas tern panhandle to the flanks of the Chattahoochee “Anticline” in the central panhandle then into the western panha ndle to Okaloosa County. In the peninsula, the Miocene sediments crop out or are in the sha llow subsurface from the northern flank of the Ocala Platform in Hamilton, Columbia and Ba ker Counties southward to Charlotte County. Some of the most beautiful landscapes in th e State occur where the Miocene sediments are exposed, eroded and often affected by karstif ication of underlying Paleogene carbonates. The importance of the Miocene sediments in Florida is twofold - first, these sediments contain valuable mineral resources, primarily phosphate and adsorptive clays; and, second, the Miocene sediments comprise the intermediate c onfining unit and aquifer system. Whereas the principle geological hazard associated with Pa leogene carbonates is karst development, the hazards associated with the Miocene sediments are radon gas and swelling clays. Significant changes in age determinations or interpretations have occurred for the sediments traditionally considered as Miocene in the peninsula. Puri and Vernon (1964) recognized a simple three-fold subdivision of the Miocene in peninsular Florida. Their

subdivision of the Miocene was that all Lower Miocene sediments were St. Marks Formation (Tampa [Note that they used Tampa as a stage na me so all sediments that had been called Tampa were placed in the St. Marks Formation statew ide]), Middle Miocene sediments were Hawthorn Formation and Upper Miocene sediments were Tamiami Formation. Poag (1972) placed the lower portion of the Chattahochee Formation in the Upper Oligocene. Currently, geologists recognize that the Hawthorn Group spans from th e mid-Oligocene to Early Pliocene (Brewster-FLORIDA GEOLOGICAL SURVEY

15 Wingard et al. , 1997; Missimer, 1997). The Tamiami Formation is Early to Late Pliocene (Missimer, 1997). The Miocene lithostratigraphic units recogni zed by this study in the panhandle include the Chattahoochee Formation, St. Marks Form ation, Alum Bluff Group, Torreya Formation (Hawthorn Group) and residuum. In the peninsula, the Miocene units mapped include the undifferentiated Hawthorn Group, Coosawhatchie Formation, Charlton Member, and the Peace River Formation and its Bone Valley Member.

Tch - Chattahoochee Formation - The Chattahoochee Formation, originally named by Dall and Stanley-Brown (1894), is predominantly a yellowish gray, poorly to moderately indurated, fine-grained, often fossiliferous (molds and casts), silty to finely sandy dolostone (Huddlestun, 1988). Siliciclastic beds and limestones may be present. The Chattahoochee Formation is exposed in Jackson County, central panhandle, on the Chattahoochee “Anticline”. It grades latera lly across the Gulf Trough into the St. Marks Formation through a broad transition area (Sco tt, 1986). The Chattahoochee Formation forms the upper part of the FAS in the central panhandle.

Tsmk - St. Marks Formation - The Lower Miocene St. Marks Formation, named by Finch (1823), is exposed in Wakulla, Leon and Jefferson Counties on the northwestern flank of the Ocala Platform. It is a white to yellowi sh gray, poorly to moderately indurated, sandy, fossiliferous (molds and casts) limestone (packstone to wackestone). Mollusk molds and casts

are often abundant. The St. Marks Formation make s up the upper part of the FAS in part of the eastern panhandle.

Hawthorn Group The Hawthorn Group in Florida is composed of a number of different formations and members (Scott, 1988; Huddlestun, 1988). Most of the formations are defined from subsurface evaluations. As a result, for mapping purposes, all the component formations are not recognized on the geologic map. In the eastern panhandle, the upper Lower Miocene Torreya Formation, including the Dogtown and Sopchoppy Members (Huddlestun and Hunter, 1982), comprises the entire Hawthorn Group (Scott, 1988). The Dogtown and Sopchoppy Members are not delineated on the map. In northern peninsular Florida, the Hawthor n Group consists of the lower Lower Miocene Penney Farms Formation and, rarely, the Par achucla Formation; the upper Lower Miocene Marks Head Formation; the Middle Miocene C oosawhatchie Formation and the Statenville Formation (Scott, 1988; Huddlestun, 1988). Th e Charlton Member of the Coosawhatchie Formation is recognized in a limited area. Th e Penney Farms and Marks Head Formations are not recognized cropping out in significant expos ures. The undifferentia ted Hawthorn Group was mapped where component formations were questiona ble or difficult to differentiate due to very

limited data. In southern peninsular Florida, the Hawthorn Group formations include the Upper Oligocene to Middle Miocene Arcadia Forma tion including the Tampa and Nocatee Members and the Middle Miocene to Early Pliocene Peace Ri ver Formation with its Bone Valley Member and Wabasso beds (Scott, 1988). The Nocatee Me mber of the Arcadia Formation and theOPEN FILE REPORT NO. 80

16 Wabasso beds of the Peace River Formation were not recognized at or near land surface and do not appear on the geologic map.

Tht - Torreya Formation - The Torreya Formati on is exposed or near the surface from western Gadsden County eastward to western- most Hamilton County. It is informally subdivided into a lower carbonate unit and an upper siliciclastic unit (Scott, 1988). The majority of Torreya Formation outcrops expose the siliciclastic part of the unit. The carbonate sediments are white to light olive gray, generally poorly indurated, variably sandy and clayey, fossiliferous (molds and casts) limestone (mudstone and wack estone). The limestones often grade into calcareous-cemented sands. Phosphate is present in the carbonate sediments, particularly in the Sopchoppy Member. The siliciclastics vary from white to light olive gray, unconsolidated to poorly indurated, slightly clayey sands with minor phosphate to light gray to bluish gray, poorly consolidated, variably silty clay (Dogtown Me mber). The siliciclastics are sporadically fossiliferous. The Torreya Formation overlies the FAS and forms part of the intermediate confining unit/aquifer system.

Thc - Coosawhatchie Formation - The Coosaw hatchie Formation is exposed or lies

beneath a thin overburden on the eastern flank of the Ocala Platform from southern Columbia County to southern Marion County. Within th e outcrop region, the Coosawhatchie Formation varies from a light gray to olive gray, poorly consolidated, variably clayey and phosphatic sand with few fossils, to an olive gray, poorly to m oderately consolidated, slightly sandy, silty clay with few to no fossils. Occasionally the sands will contain a dolomitic component and, rarely, the dominant lithology will be dolostone or limestone . Silicified nodules are often present in the

Coosawhatchie Formation sediments in the outcrop region. The sediment may contain 20 percent or more phosphate (Scott, 1988). Perm eability of the Coosawhatchie sediments is generally low, forming part of the intermediate confining unit/aquifer system.

Thcc - Coosawhatchie Formation, Charlton Memb er - The Charlton Member (originally the Charlton formation, Veatch and Stevenson, 1911), crops out only in northern Nassau County near and along the St. Marys River. The Charlton Me mber in this area consists primarily of light gray to greenish gray, poorly to moderately consolidated, dolomitic to calcareous, silty, sandy, locally fossiliferous clays. Few carbonate beds occur.

Ths - Statenville Formation - The Statenville Fo rmation occurs at or near the surface in a limited area of Hamilton, Columbia and Baker C ounties on the northeastern flank of the Ocala

Platform. The formation consists of interbe dded sands, clays and dolostones with common to very abundant phosphate grains. The sands predom inate and are light gray to light olive gray, poorly indurated, phosphatic, fine to coarse grai ned with scattered gravel and with minor occurrences of fossils. Clays are yellowish gray to olive gray, poorly consolidated, variably sandy and phosphatic, and variably dolomitic. The dolostones, which occur as thin beds, are yellowish gray to light orange, poorly to well indurated, sandy, clayey and phosphatic with scattered mollusk molds and casts. Phosphate occurs in the Statenville Formation in economically important amounts. Silicified fossils and opalized claystones are found in the Statenville Formation. Permeability of these sedi ments is generally low, forming part of the intermediate confining unit/aquifer system.FLORIDA GEOLOGICAL SURVEY

17 Th - Undifferentiated Hawthorn Group - The undifferentiated Hawthorn Group occurs at

or near the surface near the southern flank of the Ocala Platform from Gilchrist County southward to Pasco County with isolated occurre nces in Pinellas County. Correlation of these sediments to the formations of the Hawthorn Group exposed to the east and in the subsurface is uncertain. There is little to no phosphate present in these sediments and fossils are rare. Ages have not been documented but stratigraphic pos ition suggests inclusion in the Hawthorn Group. These sediments may be residual from the weat hering and erosion of the Hawthorn Group. The Hawthorn Group sediments on the Brooksville Ridge are deeply weathered and in some outcrops look like Cypresshead Formation siliciclastics. The undifferentiated Hawthorn Group sediments are light olive gray and blue gray in unweathered sections to reddish brown in deep ly weathered sections, poorly to moderately consolidated, clayey sands to silty clays and rela tively pure clays. These sediments are part of the intermediate confining unit/aquifer system a nd provide an effective aquitard for the FAS, except where perforated by karst features. Hard-rock phosphate deposits are associated with the undifferentiated Hawthorn Group

sediments on the eastern flank of the Brooksville Ridge. The hard rock phosphate deposits were formed by the dissolution of phosphate in the Hawthorn sediments and redeposition in karst

features.

Tab - Alum Bluff Group - West of the Ap alachicola River, the Hawthorn Group is replaced by the Alum Bluff Group. The Alum Bl uff Group includes the Chipola Formation, Oak Grove Sand, Shoal River Formation, Choctawh atchee Formation and the Jackson Bluff Formation (Huddlestun, 1984; Braunstein et al ., 1988). The formations included in this group are generally defined on the basis of their mo lluscan faunas and stratigraphic position (Schmidt and Clark, 1980). Puri (1953) described sediment faci es as they relate to the formations of the Alum Bluff Group These sedi ments are lithologically distinct as a group, not as individual units. Brooks (1982) mapped much of the Alum Bluff Group as the Shoal River Formation. The Alum Bluff Group crops out or is beneath a thin overburden in the western panhandle from river valleys in Okaloosa County eastward to western Jackson County. The Alum Bluff Group consists of clays, sands and shell beds which may vary from fossiliferous, sandy clays to unfossiliferous sa nds and clays and occasional carbonate beds (Huddlestun, 1984). Mica is a common constitu ent and glauconite and phosphate occur sporadically. Induration varies from essentia lly nonindurated in sands to well indurated in carbonate lenses. Colors range from cream to olive gray with mottled reddish brown in weathered sections. Sand grain size varies from very fine to very coarse with sporadic occurrences of gravel. These sediments genera lly have low permeabilities and are part of the intermediate confining unit/aquifer system.

Trm - Residuum on Miocene sediments - The undifferentiated Miocene residuum, mapped on parts of the Chattahoochee “Anticline”, characteristically consists of reddish brown, variably sandy clay with inclusions of variably fossiliferous, silicified limestone. The residuum includes Lower to Upper Miocene and younger weathered sediments.

Miocene - Pliocene SeriesOPEN FILE REPORT NO. 80

18 Middle Miocene-Lower Pliocene, Serravalian - Zanclean Stage

Thp - Peace River Formation - The Peace River Formation crops out or is beneath a thin overburden on the southern part of the Ocala Platform extending into the Okeechobee Basin. These sediments were mapped from Hillsbor ough County southward to Charlotte County. Within this area, the Peace River Formation is composed of interbedded sands, clays and carbonates. The sands are generally light gray to olive gray, poorly consolidated, clayey, variably dolomitic, very fine to medium grained and phosphatic. The clays are yellowish gray to olive gray, poorly to moderately consolidated, sandy, silty, phosphatic and dolomitic. The carbonates are usually dolostone in the outcrop area. The dolostones are light gray to yellowish gray, poorly to well indurated, variably sandy and clayey, and phosphatic. Opaline chert is often found in these sediments. The phosphate cont ent of the Peace River Formation sands is frequently high enough to be economically mined. Fossil mollusks occur as reworked casts, molds, and limited original shell material. Silic ified corals and wood, and vertebrate fossils are also present. The Peace River Formation is widespr ead in southern Florida. It is part of the intermediate confining unit/aquifer system.

Thpb - Bone Valley Member, Peace River Fo rmation - The Bone Valley Member (originally the Bone Valley Formation of Matson and Clapp, 1909), Peace River Formation occurs in a limited area on the southern part of the Ocala Platform in Hillsborough, Polk and Hardee Counties. Throughout its extent, the Bone Valley Member is a clastic unit consisting of sand-sized and larger phosphate grains in a matr ix of quartz sand, silt and clay. The lithology is highly variable, ranging from sandy, silty, phosphatic clays and relatively pure clays to clayey, phosphatic sands to sandy, clayey phosphorites (Webb and Crissinger, 1983). In general, consolidation is poor and colors range from white , light brown and yellowish gray to olive gray and blue green. Mollusks are found as reworke d, often phosphatized casts. Vertebrate fossils occur in many of the beds within the Bone Va lley Member. Shark’s teeth are often abundant. Silicified corals and wood are occasionally present as well. The Bone Valley Member is an extremel y important, unique phosphate deposit and has provided much of the phosphate production in the United States during the twentieth century. Mining of phosphate in the outcrop area began in 1888 (Cathcart, 1985) and continues to the
present.

Pliocene Series Lower Pliocene to Upper Pliocene - Zanclean to Piacenzian Stage

Florida’s Pliocene sediments have been th e focus of numerous, primarily paleontologic, investigations due to abundant and diverse mo lluscan faunas. Although the majority of the

Pliocene sediments are unfossiliferous siliciclas tics, well preserved shell beds in southern Florida have attracted much attention (s ee papers in Scott and Allmon [1992]; Zullo et al .[1993]; Missimer [1997]). Despite the attention to these units, the lithostratigraphy of the Pliocene units remains poorly understood. Pliocene sediments are distributed widely inFlorida. In the panhandle and northern twothirds of the peninsula the Pliocene sediments are predominantly unfossiliferous siliciclastics. In the southern one-third of the peninsula, the Pliocene sediments are often fossiliferousFLORIDA GEOLOGICAL SURVEY

19 siliciclastics with carbonates becoming more abunda nt in southwestern Florida. The facies relationships within the marine Pliocene sediments of southern Florida are quite complex.

Tt - Tamiami Formation - The Tamiami Forma tion (Mansfield, 1939) is a poorly defined lithostratigraphic unit containing a wide range of mixed carbonate-siliciclastic lithologies and associated faunas (Missimer, 1992). It occurs at or near the land surface in Charlotte, Lee, Hendry, Collier and Monroe Counties in the sout hern peninsula. A number of named and unnamed members are recognized within the Tamiami Formation. These include: the Buckingham Limestone Member; an unnamed tan clay and sand; an oyster ( Hyotissa ) facies, a sand facies, the Ochopee Limestone Member, th e Bonita Springs Marl Member; an unnamed limestone facies; the Golden Gate Reef Memb er; and the Pinecrest Sand Member (Missimer, 1992). The individual members of the Tamiami Formation were not separately mapped on the geological map. Lithologies of the Tamiami Formation in th e mapped area include: 1) light gray to tan, unconsolidated, fine to coarse grained, fossilif erous sand; 2) light gray to green, poorly consolidated, fossiliferous sandy clay to clayey sand; 3) light gray, poorly consolidated, very fine to medium grained, calcareous, fossiliferous sand; 4) white to light gray, poorly consolidated, sandy, fossiliferous limestone; and 5) white to li ght gray, moderately to well indurated, sandy, fossiliferous limestone. Phosphate is present in virtually all lithologies as limited quantities of sand- to gravel-sized grains. Fossils present in the Tamiami occur as molds, casts and original material. The fossils present include barnacles , mollusks, corals, echinoids, foraminifers and calcareous nannoplankton. The Tamiami Formation has highly permeable to impermeable lithologies that form a complex aquifer. Locally, it is part of the surfic ial aquifer system. In other areas, it forms a part of the intermediate confining unit/aquifer system.

Tjb - Jackson Bluff Formation - The Jack son Bluff Formation, named by Vernon and Puri (1964), occurs at or near the surface in a limited area of the panhandle in Leon, Liberty and

Wakulla Counties. It has attracted much atte ntion due to its abundant fossil molluscan fauna (Huddlestun, 1984; Schmidt, 1984). In the outcrop area, the Jackson Bluff Forma tion is described as a sandy, clayey shell bed (Schmidt, 1984). It is composed of tan to or ange-brown to gray green, poorly consolidated, fossiliferous, sandy clays to clayey sands. Foss ils present include abundant mollusks, corals,

foraminifers and occasional vertebrate remains.

Tic - Intracoastal Formation - Limited exposures and shallow subsurface occurrences of the Intracoastal Formation have been reported in northwestern Florida (B ay, Franklin, Liberty and Wakulla Counties) (Schmidt, 1984). In the subsurface, it occurs to the west across the Apalachicola Embayment (Huddlestun, 1984; Schmidt, 1984). The Intracoastal Formation is composed of light gray to olive gray, poorly indurated, sandy, clayey, highly fossiliferous limestone (grain stone and packstone). The fossils present include foraminifers, mollusks, barnacles, echinoi ds and ostracods. Quartz sand varies from very fine to coarse grained (Huddlestun, 1984).OPEN FILE REPORT NO. 80

20 Tci - Citronelle Formation - The Citronelle Formation is widespread in the Gulf Coastal Plain. The type section for the Citronelle Formation, named by Matson (1916), is near Citronelle, Alabama. The Citronelle Formation grades laterally, through a broad facies transition, into the Miccosukee Formation of the eastern Florida panhandle. Coe (1979) investigated the Citronelle Formation in porti ons of the western Florida panhandle. The Citronelle Formation is a siliciclastic, deltaic deposit that is lithologically similar to, and time equivalent with, the Cypresshead Formation a nd, at least in part, the Long Key Formation (Cunningham et al ., 1998) of the peninsula. In the west ern panhandle, some of the sediments mapped as Citronelle Formation may be reworked Citronelle. The lithologies are the same and there are few fossils present to document a possible younger age. The Citronelle Formation consists of gray to orange, often mottled, unconsolidated to poorly consolidated, very fine to very coarse, poor ly sorted, clean to clayey sands. It contains significant amounts of clay, silt and gravel which may occur as beds and lenses and may vary considerably over short distances. Limonite nodules and limonite-cemented beds are common. Marine fossils are rare but fossil pollen, plant remains and occasional vertebrates are found. Much of the Citronelle Formation is highly permeable. It forms the Sand and Gravel Aquifer of the surficial aquifer system.

Tmc - Miccosukee Formation - The Miccos ukee Formation, named by Hendry and Yon (1967), is a siliciclastic unit with a limited distribu tion in the eastern panhandle. It occurs in the Tallahassee Hills from central Gadsden County to eastern Madison County, often capping hills. The Miccosukee Formation grades to the west, through a broad facies transition, in central Gadsden County into the Citronelle Formation. The Miccosukee Formation is a prodeltaic deposit. The Miccosukee Formation is composed of grayish orange to grayish red, mottled, poorly to moderately consolidated, interbedded cla y, sand and gravel of varying coarseness and admixtures (Hendry and Yon, 1967). The unit is re latively impermeable but is considered a part of the surficial aquifer system (Southeastern Geological Society, 1986).

Tc - Cypresshead Formation - The Cypressh ead Formation named by Huddlestun (1988), is composed of siliciclastics and occurs only in the peninsula and eastern Georgia. It is at or near the surface from northern Nassau County southward to Highlands County forming the peninsular highlands. It appears that the Cypresshead Form ation occurs in the subsurface southward from the outcrop region and similar sediments, the L ong Key Formation, underlie the Florida Keys. The Cypresshead Formation is a shallow marine, near shore deposit equivalent to the Citronelle Formation deltaic sediments and the Miccosukee Formation prodeltaic sediments. The Cypresshead Formation consists of reddi sh brown to reddish orange, unconsolidated to poorly consolidated, fine to very coarse gr ained, clean to clayey sands. Cross bedded sands are common within the formation. Discoid quartz ite pebbles and mica are often present. Clay beds are scattered and not areally extensive. In general, the Cypresshead Formation in exposure occurs above 100 feet (30 meters) above mean sea level (msl). Original fossil material is not present in the sediments although poorly preserved molds and casts of mollusks and burrow structures are occasionally present. The presence of these fossil “ghosts” and trace fossils documents mari ne influence on deposition of the Cypresshead

sediments.FLORIDA GEOLOGICAL SURVEY

21 The permeable sands of the Cypresshead Form ation form part of the surficial aquifer
system.

TERTIARY-QUATERNARY SYSTEMS

TQu - Undifferentiated Tertiary-Quatern ary Sediments - These sediments are siliciclastics that are separated from undifferentia ted Quaternary sediments solely on the basis of elevation. Based on the suggestion that the Pl eistocene sea levels reached a maximum of approximately 100 feet (30 meters) msl (Col quhoun, 1969), these sediments, which occur above 100 feet (30 meters) msl, are predominantly olde r than Pleistocene but contain some sediemnts reworked during the Pleistocene. This unit may include fluvial and aeolian deposits. The undifferentiated Tertiary-Quaternary sediments occur in a band extending from the GeorgiaFlorida state line in Baker and Columbia Counties southward to Alachua County. These sediments are gray to blue green, unc onsolidated to poorly consolidated, fine to coarse grained, clean to clayey, unfossiliferous sa nds, sandy clays and clays. Organic debris and disseminated organics are present in these sediments. The undifferentiated Tertiary-Quaternary sedi ments are part of the surficial aquifer
system.

TQd - Tertiary-Quaternary Dunes - The dune se diments are fine to medium quartz sand with varying amounts of disseminated organic ma tter. The sands form dunes at elevations greater than 100 feet (30 meters) msl.

TQuc - Undifferentiated reworked Cypresshead Formation - This unit is the result of post depositional reworking of the Cypresshead silicic lastics. The sediments are fine to coarse quartz sands with scattered quartz gravel and varying percentages of clay matrix.

Pliocene - Pleistocene Series

TQsu - Tertiary-Quaternary Fossiliferous Sedi ments of Southern Florida - Molluskbearing sediments of southern Florida contain some of the most abundant and diverse fossil faunas in the world. The origin of these accumu lations of fossil mollusks is imprecisely known (Allmon, 1992). The shell beds have attracted much attention due to the abundance and preservation of the fossils but the biostratigraphy and lithostratigraphy of the units has not been well defined (Scott, 1992). Scott and Wingard ( 1995) discussed the problems associated with biostratigraphy and lithostratigraphy of the Plio -Pleistocene in southern Florida. These “formations” are biostratigraphic units. The “formations” previously recognized within the latest Tertiary-Quaternary section of

southern Florida include the latest Pliocene - early Pleistocene Caloosahatchee Formation, the early Pleistocene Bermont formation (informa l) and the late Pleistocene Fort Thompson

Formation. This section consists of fossilifer ous sands and carbonates. The identification of these units is problematic unless the signifi cant molluscan species are recognized. Often exposures are not extensive enough to facilitate th e collection of representative faunal samples to properly discern the biostratigraphic identification of the formation. In an attempt to alleviate the inherent problems in the biostratigraphic r ecognition of lithostratigraphic units, Scott (1992)OPEN FILE REPORT NO. 80

22 suggested grouping the latest Pliocene through la te Pleistocene Caloosahatchee, Bermont and Fort Thompson Formations in to a single lit hostratigraphic entity, the Okeechobee formation (informal). In mapping the shelly sands and carbonates, a generalized grouping as TertiaryQuaternary shell units (TQsu) was utilized. Th is is equivalent to the informal Okeechobee

formation. The distribution of the Caloosahat chee and Fort Thompson Formation are shown on previous geologic maps by Cooke (1945), Vernon and Puri (1964) and Brooks (1982).

The Nashua Formation occurs within the P liocene - Pleistocene in northern Florida. However, it crops out or is near the surface is an area too small to be shown on a map of this

scale. Lithologically these sediments are comple x, varying from unconsolidated, variably calcareous and fossiliferous quartz sands to we ll indurated, sandy, fossiliferous limestones (both marine and freshwater). Clayey sands and sandy clays are present. These sediments form part of the surficial aquifer system

Pleistocene Series

Qa - Anastasia Formation - The Atlantic Co astal Ridge is underlain by the Anastasia Formation from St. Johns County southward to Palm Beach County. Excellent exposures occur in Flagler County in Washington Oaks State Par k, in Martin County at the House of Refuge on Hutchinson Island and at Blowing Rocks in Palm Beach County. An impressive exposure of Anastasia Formation sediments occurs along Country Club Road in Palm Beach County (Lovejoy, 1992). The Anastasia Formation generally is recognized near the coast but extends inland as much as 20 miles (32 kilometers) in St. Lucie and Martin Counties. The Anastasia Formation, named by Sellards (1912),is composed of interbedded sands and coquinoid limestones. The most recognized facies of the Anastasia sediments is an orangish brown, unindurated to moderately indurated, coquina of whole and fragmented mollusk shells in a matrix of sand often cemented by sparry calcite. Sands occur as light gray to tan and orangish brown, unconsolidated to moderately indurated, unf ossiliferous to very fossiliferous beds. The Anastasia Formation forms part of the surficial aquifer system.

Qk - Key Largo Limestone - The Key Lar go Limestone, named by Sanford (1909), is exposed at the surface in the Florida Keys from Soldier Key on the northeast to Newfound Harbor Keys near Big Pine Key on the southwest (Hoffmeister, 1974). This unit is a fossil coral reef much like the present day reefs offshore fr om the Keys. An exceptional exposure of the Key Largo Limestone occurs in the Windley Ke y Quarry State Geological Site in the upper Florida Keys. Exposures of the limestone containing large coral heads are in a series of old quarries. The Key Largo Limestone is a white to light gray, moderately to well indurated, fossiliferous, coralline limestone composed of coral heads encased in a calcarenitic matrix. Little to no siliciclastic sediment is found in these sediments. Fossils present include corals, mollusks and bryozoans. It is highly porous and permeable and is part of the Biscayne Aquifer of the surficial aquifer system

Qm - Miami Limestone - The Miami Limestone (formerly the Miami Oolite), named by Sanford (1909), occurs at or near the surface in s outheastern peninsular Florida from Palm BeachFLORIDA GEOLOGICAL SURVEY

23 County to Dade and Monroe Counties. It forms the Atlantic Coastal Ridge and extends beneath the Everglades where it is commonly covered by th in organic and freshwater sediments. The

Miami Limestone occurs on the mainland and in the southern Florida Keys from Big Pine Key to the Marquesas Keys. From Big Pine Key to the mainland, the Miami Limestone is replaced by the Key Largo Limestone. To the north, in Pa lm Beach County, the Miami Limestone grades laterally northward into the Anastasia Formation.

The Miami Limestone consists of two faci es, an oolitic facies and a bryozoan facies (Hoffmeister et al . [1967]). The oolitic facies consists of white to orangish gray, poorly to moderately indurated, sandy, oolitic limestone (gra instone) with scattered concentrations of fossils. The bryozoan facies consists of white to orangish gray, poorly to well indurated, sandy, fossiliferous limestone (grainstone and packstone). Beds of quartz sand are also present as unindurated sediments and indurated limey sands tones. Fossils present include mollusks, bryozoans, and corals. Molds and casts of fossils are common. The highly porous and permeable Miami Limestone forms much of the Biscayne Aquifer of the surficical aquifer
system.

Qal Qbd Qtr Qu - Undifferentiated Quaternary Sedi ments - Much of Florida’s surface is covered by a varying thickness of undifferentia ted sediments consisting of siliciclastics, organics and freshwater carbonates. Where th ese sediments exceed 20 feet (6.1 meters) thick, they were mapped as discrete units. In an e ffort to subdivide the undifferentiated sediments, those sediments occurring in flood plains were mappe d as alluvial and flood plain deposits (Qal). Sediments showing surficial expression of b each ridges and dunes were mapped separately (Qbd) as were the sediments composing Trail Ridge (Qtr). Terrace sands were not mapped (refer to Healy [1975] for a discussion of the te rraces in Florida). The subdivisions of the Undifferentiated Quaternary Sediments (Qu) are not lithostratigraphic units but are utilized in order to facilitate a better understanding of the State’s geology. The siliciclastics are light gray, tan, brown to black, unconsolidated to poorly consolidated, clean to clayey, silty, unfossiliferous , variably organic-bearing sands to blue green to olive green, poorly to moderately consolidat ed, sandy, silty clays. Gravel is occasionally present in the panhandle. Organics occur as plan t debris, roots, disseminated organic matrix and beds of peat. Freshwater carbonates, often referred to as marls in the literature, are scattered over much of the State. In southern Florida, freshwater carbonates are nearly ubiquitous in the Everglades. These sediments are buff colored to tan, unconsolidated to poorly consolidated, fossiliferous carbonate muds. Sand, silt and clay may be present in limited quantities. These carbonates often contain organics. The dominan t fossils in the freshwater carbonates are

mollusks.

Holocene Series

Qh - Holocene Sediments - The Holocene sedime nts in Florida occur near the present coastline at elevations generally less than 5 f eet (1.5 meters). The sediments include quartz sands, carbonate sands and muds, and organics.OPEN FILE REPORT NO. 80

24 REFERENCES Allmon, W.D., 1992, Whence southern Florida’s Plio-Pleistocene shell beds: in Scott, T.M., and Allmon, W.D., eds., The Plio-Pleistocene stratigraphy and paleontology of southern Florida; Florida Geological Survey Special Publication 36, p. 1-20.

Applin, P. L., and Applin, E. R., 1944, Regional s ubsurface stratigraphy and structure of Florida and southern Georgia: American Associati on of Petroleum Geologists Bulletin, v. 28, p. 1673-

1753.

Arthur, J. D., 1988, Petrogenesis of Early Mesozoic tholeiite in the Florida basement and overview of Florida basement geology: Florida Geol ogical Survey Report of Investigation 97, 39

p.

Braunstein, J., Huddlestun, P., and Biel, R., 1988, Gu lf Coast region correlation of stratigraphic units

of North America: American Association of Petroleum Geologists, Correlation Chart.

Brewster-Wingard, G.L., Scott, T.M., Edward s, L.E., Weedman, S.D., and Simmons, K.R., 1997, Reinterpretation of the peninsular Florida Oligocene: An integrated stratigraphic approach: Sedimentary Geology, v. 108, p. 207-228.

Brooks, H.K., 1982, Geologic Map of Florida: Center for Environmental and Natural Resources, University of Florida.

Bryan, J.R., 1991, Stratigraphic and paleontologic studies of Paleocene and Oligocene carbonate

facies of the eastern Gulf Coastal Plain: unpublished Ph.D. dissertation, University of Tennessee, Knoxville, TN, 324 p.

Bryan, J.R., 1993, Late Eocene and Early Oligocen e carbonate facies and paleoenvironments of the eastern Gulf Coastal Plain: Geological Society of America, Southeastern Section Meeting, Tallahassee, Florida, field trip guidebook, 25 p.

Cathcart, J.B., 1985, Economic geology of the Land-Pe bble Phosphate District of Florida and its

southern extension: in Cathcart, J.B., and Scott, T.M., eds., Florida Land-Pebble Phosphate District: Geological Society of America Annual Meeting, Orlando, Florida, field trip guidebook, p. 4-27.

Coe, C. J., 1979, Geology of Plio-Pleistocene sediments in Escambia and Santa Rosa C ounties, Florida: unpublished MS thesis, Florida State University, Tallahassee, FL, 115 p.

Colquhoun, D.J., 1969, Coastal plain terraces in the Carolinas and Georgia, U.S.A.: in Wright, H.E., Jr., editor, Quaternary Geology and Climate: Volume 16 of the Proceedings of the VII Congress of the International Association for Quaternary Research, v. 16, p. 150-162.

Cooke, C. W., 1945, Geology of Florida: Fl orida Geological Survey Bulletin 29, 339 p.FLORIDA GEOLOGICAL SURVEY

25 Cooke, C. W., and Mansfield, W. C., 1936, Suwanne Limestone of Florida (abstract): Geological Society of America Proceedings, 1935, p. 71 – 72.

Cooke, C. W., and Mossom, S., 1929, Geology of Flor ida: Florida Geological Survey Twentieth Annual Report, p. 29-228, 1 plate.

Cunningham, K. J., McNeill, D. F., Guertin, L. A ., Ciesielski, P. F., Scott, T. M., and de Verteuil, L., 1998, New Tertiary stratigraphy for the Florida Keys and southern peninsula of Florida: Geological Society of America Bulletin v.110, no. 2, p. 231-258.

Dall, W.H., and Harris, G.D., 1892, Correlation pa pers - Neocene: United States Geological Survey Bulletin 84, 349 p.

________and Stanley-Brown, 1894, Cenozoi c geology along the Apalachicola River: Geological Society of America Bulletin, v. 5, p.147-170.

Finch, J., 1823, Geological essay on the Tertiary formation in America: American Journal of Science, v. 7, p. 31-43.

Healy, H.G., 1975, Terraces and shorelines of Flor ida: Florida Bureau of Geology Map Series

71.

Hendry, C. W., Jr., and Yon, J. W., Jr., 1967, Stratigraphy of Upper Miocene Miccosukee Formation, Jefferson and Leon Counties, Florid a: American Association of Petroleum Geologists Bulletin, v. 51, pp. 250-256.

Hoffmeister, J. E., 1974, Land from the sea: Univ ersity of Miami Press, Coral Gables, FL, 143 p.

_______________, Stockman, K. W., and Multer, H. G., 1967, Miami Limestone of Florida and its Recent Bahamian counterpart: Geological Society of America Bulletin 78, p. 175-190.

Huddlestun, P. F., 1984, The Neogene stratigraphy of the central Florida panhandle: U npublished Dissertation, Florida State University Depa rtment of Geology, Tallahassee, Florida, 210 p.

_________________, 1988, A revision of the lithostratigraphic units of the Coastal Plain of Georgia - The Miocene: Georgia Geological Survey Bulletin 104, 162 p.

_________________, 1993, A revision of the lithostratigraphic units of the Coastal Plain of Georgia - The Oligocene: Georgia Geological Survey Bulletin 105, 152 p.

________________, and Hunter, M. E., 1982, Stratigraphic re vision of the Torreya Formation of Florida (abstract): in Scott, T. M., and Upchurch, S. B., (eds.), Miocene of the southeasternOPEN FILE REPORT NO. 80

26 United States, Proceedings of the sympos ium: Florida Bureau of Geology, Special Publication 25, p. 210.

Lovejoy, D. W., 1992, Classic exposures of the An astasia Formation in Martin and Palm Beach Counties, Florida: Guidebook for combined Southeastern Geological Society and Miami Geological Society field trip, 31p.

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