Everglades National Park 

Geologic Resource Evaluation Report 

Natural Resource Report NPS/NRPC/GRD/NRR—2008/047 

National Park Service 

U.S. Department of the Interior 

Natural Resource Program Center 
THIS PAGE: 

Mangroves, Everglades NP 

ON THE COVER: 

Aerial view of Everglades NP 

NPS Photos 
Everglades National Park 

Geologic Resource Evaluation Report 

Natural Resource Report NPS/NRPC/GRD/NRR—2008/047 

Geologic Resources Division 

Natural Resource Program Center 

P.O. Box 25287 

Denver, Colorado 80225 

September 2008 

U.S. Department of the Interior 

Washington, D.C.
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Please cite this publication as: 

Thornberry-Ehrlich, T. 2008. Everglades National Park Geologic Resource Evaluation Report. Natural 

Resource Report NPS/NRPC/GRD/NRR—2008/047. National Park Service, Denver, Colorado. 

NPS D-345, September 2008 
 EVER Geologic Resource Evaluation Report iii 

Table of Contents 

List of Figures .............................................................................................................. iv

Executive Summary ...................................................................................................... 1

Introduction ................................................................................................................... 2

Purpose of the Geologic Resource Evaluation Program ............................................................................................2

Geologic Setting .........................................................................................................................................................2

Geologic Issues............................................................................................................. 6

Anthropogenic Impacts...............................................................................................................................................6

Aquifer Characteristics and Groundwater Flow Dynamics..........................................................................................7

Storm-influenced Sediment Transport Dynamics .......................................................................................................7

Near Coastal Response to Sea Level Rise ................................................................................................................8

Atmospheric Deposition of African Dust .....................................................................................................................9

Miscellaneous Issues and General Geologic Research Potential...............................................................................9

Geologic Features and Processes............................................................................. 12

Karst Landscape.......................................................................................................................................................12

Florida Bay ...............................................................................................................................................................12

Tree Islands, Hardwood Hammocks, and Rock Ridges ...........................................................................................13

Hydrogeology ...........................................................................................................................................................14

Map Unit Properties .................................................................................................... 20

Everglades National Park Geologic Map Unit Notes ................................................................................................21 

Map Unit Properties Table........................................................................................................................................22

Geologic History.......................................................................................................... 25

Glossary....................................................................................................................... 30

References................................................................................................................... 33

Appendix A: Geologic Map Graphic .......................................................................... 35

Appendix B: Scoping Summary................................................................................. 37

Attachment 1: Geologic Resource Evaluation Products CD 
iv NPS Geologic Resources Division 

List of Figures 

Figure 1: Everglades National Park Location and Ecosystem Map................................................................................4

Figure 2: Map of physiographic subsections in South Florida. .......................................................................................5

Figure 3: Trench dug through surficial geologic units...................................................................................................10

Figure 4: Reddish layer of African dust deposition in bedrock .....................................................................................11

Figure 5: Development of a karst landscape................................................................................................................16

Figure 7: Map of bottom types of Florida Bay ..............................................................................................................17

Figure 8: View of a rock ridge.......................................................................................................................................18

Figure 9: Cross sectional view of South Florida subsurface.........................................................................................19

Figure 10: Geologic time scale.....................................................................................................................................27

Figure 11: Evolution of the landscape in the Florida Platform area..............................................................................28

Figure 12: Freshwater limestone marl..........................................................................................................................30
 EVER Geologic Resource Evaluation Report 1 

Executive Summary 

This report accompanies the digital geologic map for Everglades National Park in Florida, 

which the Geologic Resources Division produced in collaboration with its partners. It 

contains information relevant to resource management and scientific research. 

The environment of south Florida including the 

Everglades is among the most unique on earth. Habitats 

at Everglades National Park include open marine areas, 

estuaries, mangrove zones, buttonwood ridges, coastal 

prairies, freshwater sloughs, freshwater marl prairies, 

cypress groves, tree islands, hardwood hammocks, and 

pinelands. Geology has a profound influence on these 

environments. It affects surface water flow and 

contributes to climate, hydrology, and topography in 

Florida. Geologic units and structures provide the 

foundation for the development of all ecosystems. 

With its low-lying topography, south Florida has been 

alternately submerged and exposed with variations in sea 

level for the past 50,000 years. The Everglades area is one 

of the lowest, youngest, and most geologically stable 

platforms of North America. This overall stability belies 

incredibly dynamic geologic processes at work on the 

landscape of south Florida. Beneath the surface at 

Everglades National Park, there are thousands of meters 

of roughly horizontal geologic units rich in carbonate 

minerals. These minerals dissolve in acidic solution. 

Rainwater and groundwater rich in decaying organic 

materials have dissolved interconnected void networks 

in the subsurface of south Florida. This dissolution 

ultimately results in a karst landscape characterized by 

solution holes, sinkholes, disappearing streams, springs, 

and incredible water storage capacity. 

The storage capacity of the rocks underlying Everglades 

National Park is the reason the unique ecosystems have 

flourished there through inhospitable drought seasons, 

fire danger, and seasonal hurricanes. Aquifers at various 

stratigraphic levels including the Biscayne unconfined 

surficial aquifer support the habitats at Everglades. These 

vast water resources attracted human populations to the 

area as well. 

From the late 1800s, human development has steadily 

increased in south Florida. Drastic measures were taken 

to drain swamps for agriculture and urban development. 

Canals, ditches, dams, and levees forever altered the 

once steady, slow flow of fresh water from Lake 

Okeechobee south to Florida Bay along the “River of 

Grass” – the Everglades. An intense, multiagency 

cooperative research effort is underway to restore the 

Everglades and preserve what remains of the once vast 

wetland environment of South Florida. An increased 

understanding of geologic resources must play a key role 

in these efforts at Everglades National Park. 

The following selected geologic issues (listed in detail 

with others identified by GRE scoping meeting 

participants, plus suggestions for inventory, monitoring, 

and research in the Geologic Issues section) have 

geological importance and a high level of resource 

management significance within the park: 

• Anthropogenic Impacts, 

• Aquifer Characteristics and Groundwater Flow 

Dynamics, 

• Storm-influenced Sediment Transport Dynamics, and 

• Near Coastal Response to Sea Level Rise. 
2 NPS Geologic Resources Division 

Introduction 

The following section briefly describes the National Park Service Geologic Resource 

Evaluation Program and the regional geologic setting of Everglades National Park. 

Purpose of the Geologic Resource Evaluation Program 

The Geologic Resource Evaluation (GRE) Program is 

one of 12 inventories funded under the NPS Natural 

Resource Challenge designed to enhance baseline 

information available to park managers. The program 

carries out the geologic component of the inventory 

effort from the development of digital geologic maps to 

providing park staff with a geologic report tailored to a 

park’s specific geologic resource issues. The Geologic 

Resources Division of the Natural Resource Program 

Center administers this program. The GRE team relies 

heavily on partnerships with the U.S. Geological Survey, 

Colorado State University, state surveys, and others in 

developing GRE products. 

The goal of the GRE Program is to increase 

understanding of the geologic processes at work in parks 

and provide sound geologic information for use in park 

decision making. Sound park stewardship relies on 

understanding natural resources and their role in the 

ecosystem. Geology is the foundation of park 

ecosystems. The compilation and use of natural resource 

information by park managers is called for in section 204 

of the National Parks Omnibus Management Act of 1998 

and in NPS-75, Natural Resources Inventory and 

Monitoring Guideline. 

To realize this goal, the GRE team is systematically 

working towards providing each of the identified 270 

natural area parks with a geologic scoping meeting, a 

digital geologic map, and a geologic report. These 

products support the stewardship of park resources and 

are designed for non-geoscientists. During scoping 

meetings the GRE team brings together park staff and 

geologic experts to review available geologic maps and 

discuss specific geologic issues, features, and processes. 

The GRE mapping team converts the geologic maps 

identified for park use at the scoping meeting into digital 

geologic data in accordance with their innovative 

Geographic Information Systems (GIS) Data Model. 

These digital data sets bring an exciting interactive 

dimension to traditional paper maps by providing 

geologic data for use in park GIS and facilitating the 

incorporation of geologic considerations into a wide 

range of resource management applications. The newest 

maps come complete with interactive help files. As a 

companion to the digital geologic maps, the GRE team 

prepares a park-specific geologic report that aids in use 

of the maps and provides park managers with an 

overview of park geology and geologic resource 

management issues. 

For additional information regarding the content of this 

report and up to date GRE contact information please 

refer to the Geologic Resource Evaluation Web site 

(http://www.nature.nps.gov/geology/inventory/). 

Geologic Setting 

Everglades National Park protects over 1,508,537 acres 

(fig. 1). The park contains some of the most pristine and 

unique marshland habitat in the continental United 

States and is the only subtropical preserve in North 

America. Everglades National Park was established 

under Harry S. Truman’s administration on December 6, 

1947. On October 26, 1976, the park became an 

International Biosphere Reserve and it attained 

Wilderness Designation on November 10, 1978. The 

park was made a world heritage site on October 24, 1979, 

and named a Wetland of International Importance on 

June 4, 1987. 

This vast park spans the southern tip of the Florida 

peninsula and most of Florida Bay between the peninsula 

and the Florida Keys. The environments at the park vary 

from mangrove and cypress swamps, marine and 

estuarine environments, pinelands and hardwood 

hammocks, to sawgrass prairies and rock ridges. The 

area covers a large portion of the Florida Bay, a large 

carbonate mud bank. 

South Florida lies within the Atlantic Coastal Plain 

physiographic province, one of 5 major physiographic 

provinces in the eastern United States (fig. 2). In the area 

of the Everglades, it is divided into several physiographic 

subprovinces – Everglades, Atlantic Coastal Ridge, Big 

Cypress Swamp, and Sandy Flatlands. The Everglades 

subprovince forms a south dipping, spoon-shaped lowlying area between the Atlantic Coastal Ridge to the east, 

the Big Cypress Swamp to the west, and the Sandy 

Flatlands area to the north. The basin has very low relief. 

The elevation change is only 3.6–4.3 m (12–14 ft) from 

the maximum near Lake Okeechobee to sea level at 

Florida Bay. Prior to anthropogenic alteration in the 

form of canals, ditches, and dams, this drainage system 

flowed slowly and steadily from north to south. 

Bounding the Everglades province on the east is the 

Atlantic Coastal Ridge subprovince. It is comprised of 

Pleistocene marine limestones covered by thin quartz 

sand sheets. The marine limestone is composed of tiny 

ooids of carbonate that were pushed into a linear ridge 

by long shore currents during the Pleistocene Epoch (1.8 

Ma to 10,000 years ago). The province ranges in 

elevation from 1.5–6 m (5–20 ft) in the southernmost 

portions. The width of the ridge ranges from 16 km (10 

mi) in southern Miami-Dade County and narrows to 5–8 

km (3–5 mi) further north. Periodically breaching the 

southern portions of the ridge are sloughs (transverse 

marshes) oriented perpendicular to the trend of the 

ridge. 

The southern reaches of the Everglades and Big Cypress 

Swamp subprovinces transition into the Coastal Marshes 

and Mangrove Swamp subsection. The subsection covers 
 EVER Geologic Resource Evaluation Report 3 

an area from the northeastern part of Florida Bay, 

around the southern Florida peninsula, and west, into 

the Gulf of Mexico up to the Ten Thousand Island 

region near Everglades City. Bands of swamps and 

brackish marshes sitting just above sea level characterize 

this subprovince. Freshwater runoff and tidal fluxes 

cause the salinity to change dramatically. This is why the 

mangrove, capable of enduring such salinity changes, 

thrives in this area. 

The Big Cypress Swamp subprovince defines the western 

boundary of the Everglades. The rocks underlying this 

area are among the oldest in South Florida composed of 

silts, sands, and carbonates. This area is slightly higher in 

elevation than the Everglades basin because it is 

underlain primarily by the coral-rich limestones of the 

Pliocene Tamiami Formation (3–4 Ma). This formation is 

exposed in large areas of Big Cypress National Preserve 

and in the northwest corner of Everglades National Park. 

Drainage in the subprovince is primarily to the south and 

southwest. 

 EVER Geologic Resource Evaluation Report 5 

Figure 2: Map of physiographic subsections in South Florida as defined by Brooks (1981). This map delineates subsections of larger 

physiographic subprovinces in South Florida. The Southern Atlantic Coastal Strip roughly corresponds to the Atlantic Coastal Ridge 

subprovince in the eastern areas and in southern reaches along with the Ten Thousand Islands area it corresponds to the Coastal

Marshes and Mangroves subprovince described in the text. The Devils Garden and areas north correspond approximately to the Sandy 

Flatlands subprovince. Data provided by St. Johns River Water Management District www.sjrwmd.com (accessed February 21, 2006). 

Graphic is by Trista L. Thornberry-Ehrlich (Colorado State University). . 
6 NPS Geologic Resources Division 

Geologic Issues 

A Geologic Resource Evaluation scoping session was held for Everglades National Park 

on January 24–25, 2005, to discuss geologic resources, address the status of geologic 

mapping, and assess resource management issues and needs. This section synthesizes the 

scoping results, in particular those issues that may require attention from resource 

managers. 

This section discusses the management of natural 

resources and lists the most critical topics first. Potential 

research projects and other topics of scientific interest 

are presented at the end of this section. 

Anthropogenic Impacts 

Since the late 1800s, humans have been the single most 

significant force of landscape change in the Everglades. 

Drainage of the vast wetlands was once considered 

necessary for safety, commerce, and inhabitation. The 

gently flowing water of south Florida was manipulated 

into 1,600 km (1,000 mi) of canals and 1,200 km (720 mi) 

of levees as part of the Central and South Florida Project 

authorized by Congress in 1948 (fig. 3). Overall flow is 

now controlled by 16 pump stations and over 200 gates 

and other structures. Approximately half of the 

Everglades' “River of Grass” has been developed for 

agricultural and urban use. Rivers and sloughs, such as, 

the Kissimmee River have been destroyed or converted 

to canal systems (FDEP 2005). 

A comprehensive study of the impacts of water flow 

manipulation is beyond the scope of this report; 

however, a short summary appears below. For more 

information, the Water Resource Division of the 

National Park Service has prepared a baseline inventory 

of water quality data for Everglades National Park which 

is available online (http://nrdata.nps.gov/EVER/nrdata/ 

water/baseline_wq/docs/EVERWQAA.pdf, Accessed 

July 15, 2008). Numerous interagency, cooperative 

programs such as the Everglades Program, the 

Everglades Construction Project, the Everglades Forever 

Act, and CERP are vital to the restoration and ecosystem 

health of the Everglades. Everglades National Park needs 

to continue to support and engage in efforts that affect 

the entire south Florida ecosystem. 

The results of anthropogenic water flow manipulation to 

the environment are dramatic and not well understood. 

The complex ecosystem is now largely engineered and is 

no longer buffered by the long-term water storage once 

inherent to south Florida. An average of 1.7 billion 

gallons of water discharges daily to the ocean and water 

flow to the Everglades has declined by approximately 

70%. Low freshwater input to Florida Bay is causing 

hypersaline conditions, seagrass decline, fish 

depopulation, and algal blooms. Low water levels 

(drought) cause fire danger whereas flooding threatens 

tree island and hardwood hammock ecosystems. 

Estimates are that 90–95% of the wading bird population 

has been lost and 68 plant and animal species are 

threatened or endangered in south Florida (FDEP 2005). 

Hydraulic gradients in Florida naturally push water from 

north to south causing dissolved toxins to accumulate in 

south Florida. Lake Okeechobee is eutrophied meaning 

it is so rich in mineral and organic nutrients that a 

proliferation of plant life, especially algae is reducing the 

overall dissolved oxygen content causing harm to other 

organisms. This lack of oxygen combined with increases 

in dissolved toxins pose serious threats to the aquatic 

ecosystems in the Everglades. In addition, many 

thousands of acres of Everglades marsh have been 

invaded by cattails and other opportunistic species 

(FDEP 2005). 

In 2007, Everglades National Park hosted 1,074,764 

visitors, placing increasing demands on the limited 

resources and fragile ecosystem of the park. Motorized 

boat access and fishing are restricted in the wilderness 

areas of the park. Concerns range from overuse of 

backcountry facilities, waste and pollution, and effects 

on the hydrologic system at the park due to visitor use. 

Water quality is a constant problem at Everglades 

National Park. Problems range from reductions in 

dissolved oxygen, pH, alkalinity and salinity changes, to 

high levels of pollutants such as nitrate, phosphorous, 

bacteria, mercury, and pesticides (SFWMD 2002). 

Mercury contamination of the surface water is affecting 

fish and bird of prey populations. There is a need to 

quantitatively study the interaction between 

groundwater flow and the overall fresh water and marine 

ecological quality in the Everglades. 

Earthen and Failed Dams, Canals, and Sheet Piling 

Dams and other earth works in the park pose a serious 

threat to the safety of visitors and park resources. During 

the 1930’s, a series of canals and levees were constructed 

(including East Cape canal, Homestead canal, Slegel’s 

ditch, Houseman’s ditch, and Middle Cape canal) to 

divert the water away from the “prime” real estate 

around Cape Sable. The real estate venture failed and the 

land was later included in the Everglades National Park 

boundaries. The remediation and management of the 

canals and earth works is a park responsibility. 

Canals, dams, and ditches throughout south Florida 

divert water away from the natural flow between Lake 

Okeechobee and the Everglades. Locally, near Cape 

Sable and Lake Ingraham, the flow is disrupted and 

sediment transport patterns have changed. Fresh water 

marshes behind the cape are being salinated due to the 

overall lack of fresh water input. 
 EVER Geologic Resource Evaluation Report 7 

In 2005, as a response to a technical assistance request, 

hydrologists and geomorphologists from the Water 

Resources Division, Geologic Resources Division, and 

Southeast Region of the NPS prepared a report 

evaluating the restoration alternatives for the Cape Sable 

area canals at Everglades National Park. These canals 

have caused visitor safety problems and substantially 

affected coastal morphology, sediment transport and 

deposition, and fresh–salt water exchange dynamics. 

Alternatives ranged from no action to active remediation 

such as concrete structures and plugs (Crisfield et al., 

2005). The report, available from the Geologic Resources 

Division, includes detailed descriptions of the area, the 

history of human modifications there, and remediation 

suggestions. 

Aquifer Characteristics and Groundwater Flow 

Dynamics 

The karst aquifer system of south Florida is open to 

numerous inputs of water from precipitation, surface 

flow, and artificial diversions (canals, ditches, ponds, 

etc.). The underlying Miami Limestone and Fort 

Thompson Formation form the Biscayne aquifer in the 

upper part of the surficial aquifer beneath Everglades 

National Park. The Fort Thompson Formation, 

underlying the Miami Limestone, is riddled with welldeveloped solution cavities and conduit networks 

rendering it highly permeable. The Miami Limestone is 

less permeable, lacking the same degree of connectivity 

between cavities (Bruno et al. 2003). 

Understanding the nature of the hydrologic exchange 

between surface and ground waters is critical to 

understanding the movement of water and dissolved 

nutrients, wastes, metals, etc. in the Everglades 

ecosystem (Bruno et al. 2003). Knowledge of this 

exchange has direct ties to understanding the 

hydrogeologic system of the unconfined Biscayne aquifer 

beneath the park. 

Inventory, Monitoring, and Research Suggestions for Aquifer 

Characteristics and Groundwater Flow Dynamics 

• Determine how many wells are necessary to model the 

hydrogeologic system at the park. 

• Model the porosity and permeability of the Fort 

Thompson Formation. 

• Continue studies using ground-penetrating radar, 

borehole data, and cores for characterization of the 

aquifers beneath the park (Cunningham 2004a). These 

techniques can also identify karstic characteristics of 

the subsurface. 

• Examine the salt wedge characteristics versus the 

surface water. 

• Determine if a change in hydraulic head at the 

Everglades would create positive or negative impacts 

on the overall ecosystem health. 

• Identify the extent of near-surface voids at Everglades 

National Park. 

• Survey and map fine-scale topographic variations at 

the park to apply to hydrogeologic models. Use this 

information to determine the nature of the divide 

between Taylor and Shark River Sloughs. 

• Continue studies of copepod species composition and 

distribution in the subsurface habitats at Everglades to 

better understand the exchange between surface and 

ground water (Bruno et al. 2003). 

Storm-influenced Sediment Transport Dynamics 

Because Florida sits as a peninsular boundary between 

the Gulf of Mexico and the Atlantic Ocean, it exerts a 

significant influence on climate. The peninsula marks the 

climatic zone boundary between semi-tropical and 

temperate zones. Convective heating around the Florida 

peninsula is pronounced during the summer months 

causing the development of large cumulonimbus storm 

systems and thunderstorms (Holmes and Miller 2004). 

Hurricanes are common between the months of May and 

October in the Caribbean Sea. These storms and seasonal 

hurricanes, influenced by Florida’s geologic setting, send 

torrents of rain to south Florida and are a vital 

component of the Everglades ecosystem with a 

pronounced effect on the landscape. Storm events have 

the potential to damage facilities and release toxins 

trapped in deep sediments and muds. With high-energy 

erosive events followed by flooding, these pollutants may 

be redistributed within the ecosystem. 

Determining baseline conditions would benefit resource 

management in predicting and understanding the 

environmental response to storm events. Hurricane 

Donna in 1960 evacuated water from Florida Bay by 

about 1 m (3 ft), before the water rushed back in to a 

depth of 2.1 m (7 ft). This resulted in mud deposition on 

the south side of the mud ridges and a high-energy shell 

layer deposit on the north side. In 1992, Hurricane 

Andrew caused extreme erosion that completely 

removed the highland beach area near the Ross River. 

Geochemical changes resulting from the influx of storm 

water went unmeasured during cleanup and restoration 

operations by local agencies. In 2005, many park facilities 

were damaged by hurricanes Katrina and Wilma at 

Everglades National Park. The Flamingo area suffered 

storm surges and flooding. Marinas and other areas were 

filled with mud and storm debris. These events also 

affected the natural environment at Everglades National 

Park. 

The very nature of the landscape at the Everglades is one 

of relatively rapid change. Shifting muds and sands 

continually alter the shape and profile of the shoreline. 

Sand and mud erode from one beach and are deposited 

elsewhere in the course of a single storm event. 

Understanding the sediment transport dynamics at the 

park, especially within Florida Bay and the coastal areas 

such as Cape Sable, would provide important 

information to park resource managers. 

Cape Sable is located along the southwestern coast of 

Everglades National Park. It contains a variety of features 

including Lake Ingraham, Bear Lake, Little Fox, Middle 

Fox, and East Fox Lakes, Coot Bay, Mud Bay, and many 

wave swept beach areas such as Northwest Cape, Middle 

Cape, East Cape, and Clubhouse Beach. It also contains 

remnants of manufactured canals, levees, and ditches 
8 NPS Geologic Resources Division 

created in an attempt to render the area viable real estate 

during the 1930s. Cape Sable is host to numerous rare 

species including the Cape Sable seaside sparrow, 

diamondback terrapin (Malaclemys terrapin), loggerhead 

(Caretta caretta), Indopacific gecko (Hemidactylus 

garnotii), and eastern hog nose snake (Heterodon 

platyrhinos). Cape Sable is separated from the mainland 

by Whitewater Bay. This brackish environment is fed by 

the Shark, Broad, and Harney Rivers and is bounded by a 

buttonwood embankment growing as a natural berm on 

a mud storm beach. 

The hydrogeologic system in the area around Lake 

Ingraham was altered with the construction of canals, 

roads, and levees. As a result, sediments scouring 

through the canals are being deposited in the lake basin 

(6–30 cm/year [2.4–11.8 in/year]). Lake levels are very 

low and the lake basin sediments are often exposed at 

low tide. The delta emanating from the Middle Cape 

Canal is expanding and increasing the sediment influx 

for the Florida Bay. Salinity is increasing as 80 high tides 

a year crest the low marl ridges. This erodes the ridges, 

transporting their material into the basins behind them. 

With local sea level rise, higher salinity waters are 

encroaching on the fresh water areas. This leads to a 

decline in marsh, mangrove, and prairie areas. 

Inventory, Monitoring, and Research Suggestions for Storminfluenced Sediment Transport Dynamics 

• Use sediment transport models and vegetation maps in 

a GIS to study declines in mangrove, marsh, and 

prairie areas. This decline may be related to the canal 

system or due to sea level rise around Lake Ingraham, 

or both. Sediment transport models may also be useful 

in determining if artificial structures should be 

destroyed or reestablished based on predicted 

ecosystem response. 

• Identify potential remediation efforts for eroded canal 

openings (erosion rate is 0.6–1.2 m/year, [2–4 ft/year]). 

• Determine the nature of the relationship between the 

diversion of water through canals and the buttonwood 

ridge distribution. 

• Develop a response protocol in cooperation with 

other local agencies to determine the geochemical 

effects of storm surges. 

• Perform a local inventory of selected sites to determine 

the recovery rates of mangrove zones and buttonwood 

ridges after large storm events. 

• Establish baselines of topography, mud composition 

and distribution, etc. for comparison and prediction of 

response to future events. 

Near Coastal Response to Sea Level Rise 

Sea level rise is affecting all of South Florida. While 

slowing the rate of sea level rise is beyond the resources 

of the park, monitoring sea level change, evaluating, and 

predicting impacts on the park’s landscape and 

ecosystem is an important management issue. 

Topography is among the controlling factors in 

ecosystem development at Everglades National Park. 

Topographic variations in part define the extent of 

habitats such as marine-estuary, coastal prairie, 

mangrove zones, sloughs, marl prairies, hammocks, 

pinelands, and cypress swamps. The scale of inches is 

important for the low banks and ridges where the tides 

and wind expose the entire western basins. 

Because of the low elevation and small topographic 

relief, a small change in sea level has the ability to affect 

millions of acres of Everglades. Already, saline water is 

inundating low-lying areas, especially during storm 

events. The fresh water marshes and brackish estuaries 

are under constant threat of inundation by the sea. Given 

the low relief of the park, continued rise will destroy 

much of the marsh landscape protected at the park 

including the mangrove zones, mud ridges and other 

coastal features, which normally buffer the freshwater 

wetlands from marine inundation. 

Mangrove zones and buttonwood ridges skirt the 

southern Florida coast where oscillating fresh and saline 

water conditions dominate. Here red (Rhizophora 

mangle), black (Avicennia germinans), and white 

mangroves (Laguncularia racemosa) thrive. In a sense, 

these zones define the water level and anchor shorelines. 

They form a buffering zone between the open waters of 

the coast and the freshwater uplands and wetlands. They 

also provide a nursery for shrimp and fish, and vital 

nutrients as well as shelter and nesting areas for openwater predators and several species of birds (SFWMD 

2002). A baseline needs to be established regarding sea 

level rise to determine its effect on the mangrove areas. 

Detailed topographic data would help manage this 

resource. 

In Florida Bay, sea level rise is 23 cm (9 in) in 70 years of 

recorded measurements. The Florida Bay is covered by 

an extensive system of supra- and subtidal carbonate 

mud banks, seagrass beds, coastal marl ridges, coastal 

carbonate mud ridges, mangrove peat deposits, and 

mollusk deposits. The bay stretches from the southern 

coast of Florida to the Florida Keys island reef tract over 

an area of 2,850 km2

 (1,100 mi2) (NOAA 2006). This 

environment is incredibly dynamic and unique. The 

features in the bay are strongly related to minute changes 

in elevation. Environments within the bay can change 

within centimeters of topographic relief. Understanding 

the movement of water around Florida Bay and what 

buttressing effect, if any, the mud and marl ridges have 

on water flow patterns is essential for resource 

management. Many of the freshwater marshes behind 

the ridges are changing to super saline marine lagoons 

because of sea level rise. 

Given the topographic control on the distribution of the 

various environments in Florida Bay and the coverage of 

mapping at the park, normal surficial maps are not 

sufficient for complex management decisions at the 

Everglades. An interdisciplinary approach to mapping is 

critical to producing a useful product for resource 

management. Anthropogenic, supratidal, intertidal, 

subtidal, and coastal features would all be helpful. This 

holistic ecosystem approach integrates biological, 

physical, cultural, and oceanographic parameters. Lidar 

surveys in addition to satellite imagery, multibeam 

mapping, bathymetry data, water quality and circulation, 
 EVER Geologic Resource Evaluation Report 9 

shoreline change data, pre- and post-storm comparisons, 

oceanographic data (waves, tides, currents, turbidity, 

temperature salinity, sediment transport patterns, coral 

larvae and other species distributions), etc. are essential 

for resource management at Everglades National Park. 

Sea level rise is also causing beach erosion near Cape 

Sable and Lake Ingraham. Increases in turbidity and 

changing currents with rising seas are causing large 

seagrass dieoffs and increased carbonate material 

suspension. 

Inventory, Monitoring, and Research Suggestions for Near 

Coastal Response to Sea Level Rise 

• Quantitatively correlate the relationship between 

coastal marl and carbonate mud ridges and the 

buttonwood distribution using new mapping and GIS. 

• Determine the minimum mapping unit for Florida Bay 

relevant to resource management. 

• Using new topographic mapping and current data, 

determine the flow dynamics (especially related to 

salinity patterns) in the bay. 

• Research potential remediation procedures for the 

hypersaline environments in the central portion of 

Florida Bay. 

• Research potential methods to protect the subaerial 

habitat in the coastal areas from rising sea level. 

• Continue monitoring the local rate of sea level rise. 

• Using storm surge data and information, model 

buttonwood and mangrove zone response to rising 

seas. 

• Monitor and measure the relationship between water 

level flux and elevations to determine an 

exposure/submergence index (i.e. 100% of the time 

exposed versus 0% of the time exposed). 

• Establish the height of buttonwood ridges and 

correlate this spatially with their distribution. 

• Identify the minimum mapping unit for buttonwood 

ridge and mangrove zone topographic mapping. 

• Perform fine-scale topographic mapping of the 

southern coastal areas to monitor and predict 

ecosystem response to fluctuating water levels and 

freshwater vs. saline water input. 

Atmospheric Deposition of African Dust 

Fine dust has been blowing across the Atlantic Ocean 

and deposited in south Florida for thousands of years. 

The dust is an aggregate of clay and quartz particles 

cemented with iron oxides (Holmes and Miller 2004). 

This dust is derived from the deserts, dry lake and 

streambeds, and plains of Africa. Paleosols and reddish 

(oxidized) layers atop the Miami Limestone attest to 

these airborne inputs (fig. 4). The process continues 

today, but human occupation and modern development 

on the African continent has introduced nutrients, 

elements, microbes, pesticides, soot, organics, bacteria, 

viruses, and other contaminants to the dust. 

Microbes and bacteria in the dust could pose biological 

threats to plant and animal species, not to mention 

humans. The fine dust diminishes air and water visibility. 

A peak of dust fall in the 1980s coincided with a sea 

urchin disease and other benthic die-offs in south 

Florida. Lead, arsenic, phosphate, copper, iron, and 

mercury concentrations in the surface sediments in the 

middle of Florida Bay are highest in low tidal flux areas. 

Toxic concentrations may be liberated to exposure 

during high tide, hurricane, and other storm surge 

events. Mercury, arsenic and other metals are 

significantly higher in samples collected throughout 

south Florida than average crustal rocks. African dust 

supplies close to 25% of the arsenic deposited in soils in 

the southeastern United States (Holmes and Miller 

2004). Awareness of this potential issue may help 

resource management anticipate environmental response 

to the contaminants in airborne dust. 

Inventory, Monitoring, and Research Suggestions for 

Atmospheric Deposition of African Dust 

• Expand and utilize the many 9.1 m (30 ft) monitoring 

wells in Florida Bay to identify and measure 

contaminant concentrations in dust, monitor rate of 

dust deposition, etc. (Gene Shinn, personal 

communication 2005). 

• Spatially monitor dust levels and study potential 

correlations with environmental responses such as 

hypersalinity and dieoffs. 

Miscellaneous Issues and General Geologic Research 

Potential 

Major ongoing research and restoration efforts 

Everglades National Park has been the site of intense 

scientific interest and ecosystem restoration efforts for 

decades. Multiple research studies are ongoing. A wealth 

of information exists on the ecosystem at the park and a 

major multi-agency effort is underway with the goals of 

understanding the controls on this ecosystem, 

determining the best ways to restore it, and finding ways 

for humans to coexist with the natural Everglades. 

Agencies such as the National Park Service, the U.S. 

Geological Survey, the National Oceanic and 

Atmospheric Administration, the U.S. Army Corps of 

Engineers, the Florida Geological Survey, and the South 

Florida Water Management District among many others 

are making strides to accomplish these goals. 

Useful resources for up-to-date information on research 

and restoration efforts for Everglades National Park 

include the South Florida Water Management District’s 

Living Everglades website 

(http://glades.sfwmd.gov/empact/home/index.shtml), 

the website for the Comprehensive Everglades 

Restoration Plan (CERP) 

(http://fl.water.usgs.gov/CERP/cerp.html), and the U.S. 

Geological Survey’s South Florida Information Access 

(SOFIA) integrated science website 

(http://sofia.usgs.gov/). 

Paleoclimates 

Cores from Florida and Biscayne Bays, and numerous 

sloughs in the park contain peat and pollen which can 

serve as representative indicators of past climates. 
10 NPS Geologic Resources Division 

Pleistocene and Holocene climatic shifts are relevant to 

establish baseline data for future predictions and to 

interpret modern patterns. Increasing the spatial density 

of cores would improve efforts to determine the 

temporal relationships of climate shifts and to make 

accurate interpolations between points for recreating 

past landscapes. 

Bioturbation, agriculture, quarrying, and other ground 

disturbances (e.g., railroad infill effects) distort the 

subsurface features. More unconsolidated sediment core 

studies would increase coverage and understanding of 

paleoclimates at the Everglades. Further identification of 

pollen species is vital to this goal. 

Archaeological Sites 

There are several sites, approximately 12,000 years old, 

along ancient coastlines and within hardwood 

hammocks and tree islands that contain artifacts from 

local indigenous populations. Artifacts include pottery 

fragments, tools made of material obtained through 

trading with northern indigenous groups, and other 

implements. Mapping and/or reconstructing these sites 

would add to the cultural value of the park. An 

interesting interpretive story may describe how people 

lived in this wetland environment before roads, trails and 

other facilities were in place. These studies may 

additionally help reconstruct the location and pattern of 

change of the paleoshoreline in the Ten Thousand Lakes, 

and Cape Sable areas. 

“Lake Belt” Management 

The term “Lake Belt” refers to a series of quarries near 

the park. These features are intended to supply water to 

the park as part of a restoration effort. There is some 

concern about how these features are affecting 

groundwater movement. Some USGS monitoring wells 

are located near levees, but more wells would increase 

understanding of the local hydrogeologic system. 

Local agriculture introduces sulphates, phosphorus, and 

other contaminants into the groundwater near these 

lakes that, given the permeable, conduit-rich bedrock, 

could easily contaminate the water in the quarries and 

affect the ecosystem of the park.

Figure 3: Trench dug through surficial geologic units near Rock Reef Pass at Everglades National Park. Photograph is by Trista L. 

Thornberry-Ehrlich (Colorado State University). 
 EVER Geologic Resource Evaluation Report 11 

Figure 4: Reddish layer of African dust deposition in bedrock at Elliot Key of nearby Biscayne National Park. Photograph by Trista L. 

Thornberry-Ehrlich (Colorado State University). 
12 NPS Geologic Resources Division 

Geologic Features and Processes 

This section describes the most prominent and distinctive geologic features and processes 

in Everglades National Park. 

Karst Landscape 

Karstic landforms are nearly synonymous with south 

Florida. Karst is a term that refers to a characteristic 

terrain produced by the chemical erosion of limestone or 

dolomite (carbonate rocks). Dissolution occurs when 

acidic meteoric water and groundwater undersaturated 

with respect to calcium carbonate react with carbonate 

rock surfaces along cracks and fractures slowly 

dissolving the rocks. Most meteoric water is of relatively 

low pH in the form of acid rain and becomes more acidic 

as it flows through decaying plant debris and soils (FGS 

2005). Most of the limestones and dolomites in the 

Everglades are inherently porous. 

At Everglades National Park, the dominant surficial 

geologic units include the Miami Limestone and the 

underlying shallow water limestone of the Fort 

Thompson Formation. These units comprise the 

uppermost 17 m of cored section in the Everglades. The 

Miami Limestone is ~125 – 130 thousand years old and 

contains two facies, the oolitic facies and the bryozoan 

facies, which intermingle in most of the outcrops at 

Everglades National Park (Cunningham 2005). These 

carbonate units are susceptible to dissolution. 

Over hundreds of thousands of years since the last 

significant interglacial period led to the flooding of the 

Florida platform (approximately 130 thousand years 

ago), dissolution has occurred between the intergranular 

pores and along fractures altering the rock and creating 

larger and larger voids (fig. 5). The system of 

underground voids and conduits in south Florida is 

extensive. Collapse of overlying rock and soil into a void 

produces a solution hole (also referred to as a sinkhole), 

which may be connected to an underground conduit (fig. 

6). If the solution hole occurs in a streambed, it may 

capture the water flow creating a disappearing stream. 

When groundwater, under hydraulic pressure, 

discharges from an underground drainage system, a 

spring is formed (FGS 2005). 

Solution holes are an obvious element of the karst 

topography at the park. Large solution holes formed in 

the Miami Limestone when sea level and the water table 

were lower than present levels. As sea level has increased 

during the Holocene (a trend that continues in south 

Florida), many of the lower elevation solution holes have 

filled with organic material and marl. As organic material 

continues to decay, lowering the pH of the groundwater 

with inputs of carbonic acid, further dissolution of the 

near surface limestones continues at Everglades National 

Park. Many of the larger solution holes found in the 

pinelands are likely due to the collapse of small 

subsurface caves (fig. 6) (Cunningham 2005). Open 

cavities or threat of future collapse may compromise 

visitor safety; however, they are a vital component to the 

ecosystem providing essential habitat for fish and other 

wildlife especially during the dry winter months at 

Everglades National Park. Solution holes often fill with 

peat and other organic material that support larger tree 

species. If build up of peat continues, in time, a tree 

island or hardwood hammock may develop. 

Solution holes (approximately 50) occur throughout the 

park (especially in the eastern half) and need to be 

systematically located, mapped, and described in terms 

of distribution, depth, interconnectedness, and other 

characteristics for resource management decision 

making. It is unknown how these solution holes impact 

the hydrogeologic regime including retention time, 

hydraulic head, and water storage. Potential data sources 

include aerial photography and field surveys. Continued 

research would be necessary to determine the degree of 

active dissolution, and the connectivity between 

subsurface conduits. 

Borrow pits and canals intersect the permeable geologic 

units in many locations of the park, affecting local water 

flow (fig. 3). A hydrogeologic model detailing how water 

flows in the park with respect to karst features and 

artificial features such as canals and ditches would be a 

valuable resource management tool. 

Florida Bay 

Simply defined, Florida Bay is a shallow inner-shelf 

lagoon located between the mainland and the Florida 

Keys island reef tract. It is the southern terminus of the 

south Florida watershed. However, Florida Bay is 

anything but simple. Freshwater, flowing from the 

Everglades, mixes with salt water from the Gulf of 

Mexico in this shallow basin forming a vast estuary. The 

bay is approximately 2,850 km2 (1,100 mi2) of mangrove 

islands and peat deposits, interconnected basins, grassy 

supra- and subtidal carbonate mud banks, mud-mounds, 

coastal marl and carbonate mud ridges, and open shallow 

water. The average water depth of the bay is only 1 m (3 

ft); thus the features in the bay and the corresponding 

ecosystem are strongly related to minute changes in 

elevation on the order of centimeters of relief (FLMNH 

2006; NOAA 2006) 

A bottom type survey of Florida Bay was conducted by 

the U.S. Geological Survey in 1996–1997. The bottom 

types surveyed did not include mangrove islands. Bottom 

types were primarily defined on the basis of seagrass 

density and sediment texture as well as overall structure. 

Bottom types included bank top suite, open mud, 

hardbottom, sparse seagrass cover, intermediate seagrass 

cover, dense seagrass cover, mixed bottom suite, and 

open sandy areas (fig. 7) (Prager and Halley 1997). Bank 

top suite refers to bottom types including mud banks at 

depths typically less than 0.6 m (2 ft) dominated by 

carbonate mud, sand, and locally, gravel in a series of 

linear sedimentary facies (Bosence 1995; Prager and 
 EVER Geologic Resource Evaluation Report 13 

Halley 1997). Open mud is used to describe areas where 

little to no seagrass cover (or other benthic fauna except 

algal mats) is present. These may be areas of former 

seagrass dieoff (Prager and Halley 1997). 

Hardbottom is the term used to describe areas with little 

to no benthic fauna cover as in open mud; however, 

unconsolidated sediment thickness in hardbottom is 5 

cm (2 in) or less. Sparse to dense seagrass cover refers to 

areas in which 50 to 100% of the bottom is exposed. 

Penincilus, Batophora, and scattered sponges occur in 

these areas. Sediments are muddy carbonate sands, sandy 

mud, or sand and are often up to 2 m (6 ft) thick. Seagrass 

tends to trap sediments in these areas. Mixed bottom 

suite as the name suggests, describes highly variable 

bottom areas. Variations in sea grass density, open mud 

areas, and sediment type are spatially extreme. Open 

sandy areas generally occur in the boundary areas 

between the Gulf of Mexico and Florida Bay. No 

significant life is present in these areas of coarse shelly 

carbonate sands (Prager and Halley 1997). 

Much study has been devoted to understanding the 

origin and anatomy of biodetrital mud-mounds. Early 

study suggested these features were biogenic structures 

formed by trapping and binding of algal aragonitic mud. 

Later research indicated the mud was both calcite and 

aragonite derived from the in situ breakdown of shell 

material in the bay. Current studies indicate these 

mounds initiate as aggradational grass-bed deposits and 

packstones, which are overlain with layered mudstones 

and erosional (winnowed) surfaces. Wind-driven (storm) 

currents flow from the northeast to the southwest 

scouring winnowed grainstones and mud-pebble 

conglomerates from the mounds to deposit on the 

leeward side. Currents from the southeast represent fairweather flow. Thus, the morphology and distribution of 

the mounds and other depositional features in Florida 

Bay are a complex response to storm influenced physical 

erosion and redeposition of sediments and fair-weather 

biogenic and physical deposition processes (Bosence 

1995). 

South Florida has predominantly been a site of carbonate 

accumulation since the Mesozoic Era. These sediments 

are thousands of meters thick. Beneath the Florida Bay 

lime muds accumulated and slowly turned to rock 

forming Pleistocene-age limestones. Much of this mud is 

biogenic and forms slowly. Other deposits within Florida 

bay come from the breaking down of shell material and 

storm driven deposition (Shinn et al. 1997). 

Understanding landscape evolution during late 

Holocene sea level rise (a 23 cm [9 in] rise in sea level in 

70 years) may prove critical to predicting future response 

to sea level changes. Because Florida Bay is such a broad, 

shallow basin, even moderate sea level rise is expected to 

have significant impacts to the biota and environments 

found there. This response is poorly understood and 

change is occurring at alarming rates. Many of the 

freshwater marshes behind the mud ridges are changing 

to super saline marine lagoons as less freshwater (50% 

reduction over the past century) infiltrates the bay from 

the northern watershed (FLNHM 2006). As sea level 

rises, many of the low-lying mangrove forest areas may 

be flooded. Florida Bay has experienced seagrass dieoffs, algal blooms, and declining populations in 

indigenous sponges, shellfish, and other species 

(Brewster-Wingard 2001). How these symptoms relate to 

sea level rise and human activities is a significant 

question for future research at Everglades National Park. 

Tree Islands, Hardwood Hammocks, and Rock Ridges 

Tree islands and larger hardwood hammocks are unique 

and prevalent features at Everglades National Park. Their 

elevated forests dot the sawgrass prairies throughout the 

park. Bay heads, precursors to hammocks, are tree 

islands dominated by broad-leaved, evergreen and 

swamp hardwood species. These areas exist on high peat 

benches above the surrounding marsh and often develop 

at solution holes or relative depressions in the solid 

bedrock. Peat and other organic material accumulate in 

the depression and nurture the development of larger 

trees and forests. Peat continues to accumulate until a 

topographic high is created (fig. 8). If this peat creation 

continues without loss to fires, hardwood hammocks 

ultimately develop. 

Hardwood Hammocks are a climax community of dense 

vegetation developed in a long-standing absence of fire. 

The presence of deeper water and/or high humidity 

dense vegetation shelters the hammocks from fire danger 

whereas temperature and salinity changes may limit the 

development of hardwood hammocks (McPherson et al. 

1976). At Everglades National Park, the hammock areas 

contain some of the rarest and most unusual plant and 

animal species. Over 100 species of trees and shrubs 

occur, ranging from red maple and laurel oak trees in the 

lower hammock areas to live oak and cabbage palm in 

high parts of the northern hammock areas. To the south, 

tropical species such as strangler fig, wild tamarind, 

pigeon plumb, gumbo limbo, poisonwood, coco plum, 

redbay, and other broad-leaved tropical trees and shrubs 

dominate the hammocks (McPherson et al. 1976). 

The existence and origin of hammocks is dependent 

upon the underlying geology and geologic processes. 

Hammock development depends upon having land 

slightly higher than that of the surrounding marshes and 

prairies. This higher land supported ancient human 

occupations as evidenced by pottery fragments, metal 

containers, and planted exotic species. In south Florida, 

this elevation difference is usually less than a meter. 

Hammock development is slow because organic material 

must build up over many years to create a topographic 

high (McPherson et al. 1976). Bedrock units may provide 

a source of phosphorous for the hardwood forests of 

hammocks, tree islands, and rock ridges, described 

below. Hydrogeochemical studies are necessary to 

identify or quantify this relationship. 

Spatially, tree islands and hardwood hammocks are 

oriented in linear trends. The islands and hammocks may 

be located in bedrock highs or lows. Some believe they 

develop in peat depressions caused by organic 

deposition into solution holes, or perhaps on a laminated 

duracrust formed by phosphorus from evaporites pulled 

up by the trees in the groundwater. 
14 NPS Geologic Resources Division 

Locally referred to as rock reefs, rock ridges, such as that 

at Rock Reef Pass, are subtle, enigmatic linear features on 

the Everglades landscape. There are approximately 20 

rock ridges in south Florida most of which are oriented 

perpendicular to the prevailing direction of water flow 

(Hickey personal communication 2005). These ridges 

trend northwest-southeast and are typically 10–20 km 

(6–12 mi) long and usually less than 100 m (330 ft) wide. 

The amount of relief associated with these ridges is small, 

approximately 0.9–1.5 m (3–5 ft). However, topographic 

relief is significant in south Florida on the scale of 

centimeters and the vegetation changes across these 

ridges and makes them appear more pronounced (fig. 7). 

The elevated ridges slow the southward flow of surface 

water, ponding water on their northern sides, and are 

responsible for significant changes in vegetation on 

either side of the ridge axis. These features, eight of 

which are named on USGS topographic maps, are 

especially evident on aerial photographs of the 

Everglades (Hickey 2005). 

Many theories abound regarding the existence of these 

features. They may be paleoshores, results of Pleistocene 

wrench faulting, developed fractures, concentrations of 

shells in oolite, paleo mudbanks, or the result of 

differential compaction and fracturing. The uniqueness 

of these environments makes understanding the origin 

and nature of their existence important to resource 

management at Everglades National Park. Studies such 

as rotary core drilling, well monitoring (for groundwater 

geochemistry), and subsurface ground penetrating radar 

surveys (to determine subsurface geologic structures) 

may shed light on the origin and distribution of these 

features as well as provide more information about their 

effects on the hydrogeologic system at Everglades 

National Park (Hickey 2005). 

Hydrogeology 

As peat and marl were deposited in a karstic limestone 

depression during the past 5,000 years, an extensive 

subtropical wetland ecosystem developed into the 

current Florida Everglades (Bruno et al. 2003). Until the 

late 1800s, interconnected wetlands covered 

approximately 8.9 million acres of south Florida. Of this 

expanse, over 4 million acres were known as the “River 

of Grass”—the Everglades. Perhaps the most critical 

feature of this ecosystem was the gently sloping 

landscape and its large capacity of long-term water 

storage. The water flowed very slowly through the 

system, buffering extreme changes caused by droughts 

and floods. Understanding this system means 

understanding the relationship between geology and 

water flow (FDEP 2005). 

Hydrogeology refers to the study of groundwater 

movement with specific emphasis on its relation to the 

surrounding geology, modes of movement, and water 

chemistry (FGS 2005). This study is multifaceted and 

interdisciplinary combining hydrology, geology, 

chemistry, physics, biology, mathematics (modeling), and 

engineering to understand the characteristics of 

groundwater movement in the complex subsurface. 

Groundwater is the most available source of potable 

water in south Florida. Water-bearing rocks at 

Everglades National Park include carbonate limestone 

and dolostone (a rock rich in dolomite). As described 

above in the karst description, these rocks are heavily 

dissolved in the subsurface and are highly permeable. 

Permeability refers to the degree to which water is able to 

flow freely through a rock (FGS 2005). 

When groundwater collects in subsurface zones, it is 

referred to as an aquifer. A viable aquifer typically yields 

water in sufficient quantities to support human activities 

such as agriculture and domestic use. Aquifers are 

classified as unconfined, semi-confined, or confined 

based on the physical parameters by which the water is 

contained in the aquifer. Unconfined aquifers are 

defined as having the general water table as an upper 

boundary. These are open to meteoric water filtering 

through the soil and subsurface and are thus susceptible 

to pollution from agricultural and domestic use. 

A confined aquifer is any water bearing layer that is 

sandwiched between two aquitards. An aquitard is a 

layer of rock that is so impermeable it cannot transmit 

useful amounts of groundwater (IGS 2006). Semiconfined aquifers share characteristics of confined and 

unconfined aquifers that vary spatially. 

The Florida aquifer system contains all three types of 

aquifers described above. This system underlies all of 

Florida and is the main source of water for most human 

use (FGS 2005). This system resides at different 

stratigraphic levels below the surface. The unconfined 

Biscayne aquifer, prominent in the Everglades, is 

comprised of karstic Pleistocene platform carbonates of 

the Miami Limestone and Fort Thompson Formation 

(fig. 9) (Cunningham 2004a; Cunningham 2004b)). The 

high porosity and permeability of these units allows 

considerable exchange between surface and ground 

waters (Bruno et al. 2003). Over portions of south 

Florida, a cap rock cover on the porous limestone exerts 

control on the surface flow of water and its subsequent 

infiltration into the groundwater. Cap rock, bedrock 

structures (pinnacles) and dissolution features such as 

solution cavities, buried sinkholes, and conduit networks 

create significant issues for hydrogeologic modeling at 

the Everglades (Kruse et al. 2000). 

With the recent funding of the Comprehensive 

Everglades Restoration Plan (CERP), innovative and vital 

research and studies are underway to understand the 

changes in the natural habitats of the Everglades as a 

result of human activities. CERP intends to restore 

natural patterns of water flow and all data related to the 

hydrogeologic system at Everglades National Park is 

critical to this goal. This cooperative effort is multiagency with involvement from the National Park Service, 

National Oceanic and Atmospheric Association, U.S. 

Geological Survey, Florida Department of 

Environmental Protection, South Florida Water 

Management District, U.S. Army Corps of Engineers, 

Florida Geologic Survey, South Florida Natural 

Resources Center, Florida International University, etc. 

(Loftus et al. 2001; SFWMD 2002). 
 EVER Geologic Resource Evaluation Report 15 

Figure 5: Development of a karst landscape from early dissolution of bedrock to the ultimate formation of a hardwood hammock in the 

Everglades. Graphic is by Trista L. Thornberry-Ehrlich (Colorado State University). 
16 NPS Geologic Resources Division 

Figure 6: Solution holes formed by collapse of uppermost rock layer in Everglades National Park. Photographs by Trista L. ThornberryEhrlich (Colorado State University). 
 EVER Geologic Resource Evaluation Report 17 

Figure 7: Map of bottom types of Florida Bay. Preliminary map is by the U.S. Geological Survey. 
18 NPS Geologic Resources Division 

Figure 8: View of a rock ridge (Rock Reef Pass, 1 m [3 ft] of relief) in Everglades National Park. Note vegetation pattern. Photograph is by 

Trista L. Thornberry-Ehrlich (Colorado State University). 
 EVER Geologic Resource Evaluation Report 19 

Figure 9: Cross sectional view of south Florida subsurface in the vicinity of Everglades National Park. Note the location of the different 

aquifer systems (surficial-Biscayne, intermediate, and Floridan systems) and geologic units. Graphic is by Trista L. Thornberry-Ehrlich 

(Colorado State University) using information from Cunningham (2005) and SFWMD (2002). 
20 NPS Geologic Resources Division 

Map Unit Properties 

This section identifies characteristics of map units that appear on the Geologic Resource 

Evaluation digital geologic map of Everglades National Park. The accompanying table 

is highly generalized and is provided for background purposes only. Ground-disturbing 

activities should not be permitted or denied on the basis of information in this table. 

Geologic maps facilitate an understanding of Earth, its 

processes, and the geologic history responsible for its 

formation. Hence, the geologic map for Everglades 

National Park informed the “Geologic History,” 

“Geologic Features and Processes,” and “Geologic 

Issues” sections of this report. Geologic maps are 

essentially two-dimensional representations of complex 

three-dimensional relationships. The various colors on 

geologic maps represent rocks and unconsolidated 

deposits. Bold lines that cross and separate the color 

patterns mark structural features such as faults and folds. 

Point symbols indicate features such as dipping strata, 

sample localities, mine features, wells, and cave openings. 

In serving the conservation and recreation needs of the 

nation, resource managers consider other resources—

water, soils, vegetation, and cultural—in concert with 

geology. Incorporation of geologic data into a geographic 

information system (GIS) increases the utility of geologic 

maps and clarifies spatial relationships to other natural 

resources and anthropogenic features. 

Geologic maps are indicators of water resources because 

they show which rock units are potential aquifers and are 

useful for finding seeps and springs. Geologic maps do 

not show soil types and are not soil maps, but they do 

show parent material, a key factor in soil formation. 

Furthermore, resource managers have used geologic 

maps to make correlations between geology and biology; 

for instance, geologic maps have served as tools for 

locating threatened and endangered plant species. 

Although geologic maps do not show where future 

earthquakes will occur, the presence of a fault indicates 

past movement and possible future seismic activity. 

Geologic maps will not show where the next landslide, 

rockfall, or volcanic eruption will occur, but mapped 

deposits show areas that have been susceptible to such 

geologic hazards. Geologic maps do not show 

archaeological or cultural resources, but past peoples 

may have inhabited or been influenced by various 

geomorphic features that are shown on geologic maps: 

alluvial terraces may preserve artifacts, and inhabited 

alcoves may occur at the contact between two rock units. 

The features and properties of the geologic units in the 

following table correspond to the accompanying digital 

geologic data. Map units are listed from youngest to 

oldest. Please refer to the geologic time scale (fig. 10) for 

the age associated with each time period. This table 

highlights characteristics of map units such as 

susceptibility to hazards; the occurrence of fossils, 

cultural resources, mineral resources, and caves; and the 

suitability as habitat or for recreational use. The 

following are source data for the GRE digital geologic 

map: 

Scott, T. M. 2001. Geologic Formations of Florida (digital). 

Scale 1:126,720. Open-File Report 80. Tallahassee, 

Florida: Florida Geological Survey. 

Green, R., K. Campbell, and T. Scott. 1996. Surficial and 

bedrock geology of the western portion of the USGS 

1:100,000 scale Homestead quadrangle. Scale 1:100,000. 

Open File Map Series 83/08-12. Tallahassee, Florida: 

Florida Geological Survey. 

Green, R., K. Campbell, and T. Scott. 1995. Surficial and 

bedrock geology of the eastern portion of the USGS 

1:100,000 scale Homestead quadrangle. Scale 1:100,000. 

Open File Map Series 83/01-07. Tallahassee, Florida: 

Florida Geological Survey. 

Green, R., K. Campbell, T. Scott, and G. Means. 1998. 

Surficial and bedrock geology of the eastern portion of 

the USGS 1:100,000 scale Sarasota quadrangle and the 

western portion of the Arcadia quadrangle. Scale 

1:100,000. Open File Map Series 87. Tallahassee, 

Florida: Florida Geological Survey. 

Green, R., G. Means, T. Scott, J. Arthur, and K. 

Campbell. 1999. Surficial and bedrock geology of the 

eastern portion of the USGS 1:100,000 scale Arcadia 

quadrangle, south-central Florida. Scale 1:100,000. 

Open File Map Series 88. Tallahassee, Florida: Florida 

Geological Survey. 

Green, R., Scott, T., Campbell, K., Arthur, J., and Means, 

G.H. 1997. Surficial and bedrock geology of the western 

portion of the USGS 1:100,000 scale Sarasota 

quadrangle, south-central Florida. Scale 1:100,000. 

Florida Geological Survey Open File Map Series 86. 

Tallahassee, Florida: Florida Geological Survey. 

McCartan, L. and W. Moy. 1995. Geologic maps of the 

Sarasota and Arcadia, Florida 30x60-minute 

quadrangles. Scale 1:100,000. OF-95-261. Reston, VA: 

U.S. Geological Survey. 

Causaras, C.R. 1985. Geology of the surficial aquifer 

system, Broward County, Florida. Scale 

1:134,000.Water-Resources Investigations Report 84. 

Reston, VA: U.S. Geological Survey. 

Causaras, C.R. 1986. Geology of the surficial aquifer 

system, Dade County, Florida: USGS Water-Resources 

Investigations Report 86. Reston, VA: U.S. Geological 

Survey. 

Bergendahl, M.H. 1956. Stratigraphy of parts of De Soto 

and Hardee Counties, Florida. Scale 1:158,400. Bulletin 

1030-B. Reston, VA: U.S. Geological Survey. 
 EVER Geologic Resource Evaluation Report 21 

Reese, R.S. and K.J. Cunningham. 2000. Hydrogeology of 

the gray limestone aquifer in southern Florida. Scale 

1:675,000. Water-Resources Investigations Report 99-

4213, Reston, VA: U.S. Geological Survey. 

Florida Fish and Wildlife Commission Florida Marine 

Research Center. 1999. Benthic Habitats of Florida Bay, 

FL 1991-1995, CD-ROM. Scale 1:48,000. National 

Oceanic and Atmospheric Administration Coastal 

Services Center. 

Yon, J.W., S.M. Spencer, R.W. Hoenstine, and E. Lane. 

1988. Mineral resources of Collier County, Florida.

Scale 1:126,720. Map Series 120. Tallahassee, Florida: 

Florida Geological Survey. 

Lane, E., T.M. Scott, R.W. Hoenstine, and J.W. Yon. 

1990. Mineral resources of Lee County, Florida. Scale 

1:126,720. Map Series 130. Tallahassee, Florida: 

Florida Geological Survey. 

Arthur, J.D., A.E. Baker, J.R. Cichon, A.R. Wood, and A. 

Rudin. 2005. Florida Aquifer Vulnerability Assessment 

(FAVA): Contamination potential of Florida's principal 

aquifer systems. Florida Geological Survey Bulletin [in 

review]. Tallahassee, Florida: Florida Geological 

Survey. 

Using ESRI ArcGIS software, the Geologic Resource 

Evaluation team created a digital geologic map from this 

source. GRE digital geologic-GIS map products include 

data in ESRI shapefile and coverage GIS formats, FGDC 

metadata, a Windows HelpFile that contains all of the 

ancillary map information and graphics, and an ESRI 

ArcMap map document file that easily displays the map 

with appropriate symbology. 

GRE digital geologic data are included on the attached 

CD and are available through the NPS Data Store 

(http://science.nature.nps.gov/nrdata/). 

Everglades National Park Geologic Map Unit Notes 

The topographic relief in Everglades National Park is 

slight and only a few distinct units are revealed at the 

surface. Cores such as the deep, continuous core near the 

Everglades National Park Research Center (W-17232), 

those of the South Florida Drilling Project (Florida 

Geological Survey, University of Miami, Florida 

Department of Transportation), and the USGS help 

define the stratigraphy underlying the park. This 

stratigraphy includes carbonate-clastic and evaporite 

units that have been accumulating for millions of years. 

The lowest unit penetrated by the W-17232 core in the 

park is the Arcadia Formation (top surface at 147 m [482 

ft] below the ground surface). As mapped, the Arcadia 

Formation is exposed on the southwestern flank of the 

Ocala Platform from Pasco County southward to 

Sarasota County in the northwestern portion of the park 

(Scott 2001). The Suwannee Limestone and Avon Park 

Formation (not penetrated by the W-17232 core) 

underlie this unit in Everglades National Park. 

A major disconformity marks the boundary between the 

Arcadia Formation and the overlying Peace River 

Formation. The Peace River Formation contains two 

distinct units: a lower diatomaceous mudstone, and an 

upper fine-grained quartz muddy sandstone 

(Cunningham et al. 1998). The Bone Valley Member of 

the Peace River Formation occurs in a limited area in 

Hillsborough, Polk, and Hardee Counties and contains 

unique phosphatic deposits (Scott 2001). The Peace 

River Formation unit pinches out south of Everglades 

National Park. The top of the Peace River Formation is 

98.8 m (324 ft) below the surface at W-17232 (McNeill et 

al. 1996). In the western areas of south Florida, the 

Pliocene carbonate-siliciclastic Tamiami Formation is 

exposed atop the Peace River Formation. 

Cunningham et al. (1998) proposed a new unit, the Long 

Key Formation, for subsurface siliciclastics underlying 

the southernmost reaches of Florida (from core W-17156 

on Long Key). This unit is coeval with the Stock Island 

Formation of the lower Florida Keys and the 

Cypresshead Formation of the peninsula (Guertin et al. 

1999; Scott 2001). The top of the Long Key Formation in 

the park is 17.4 m (57 ft) below the surface. The 

siliciclastics of the unit were deposited in at least three 

high-energy pulses. They are present in a channelized 

morphology of coarse-grained sands (>1 mm) (Warzeski 

et al. 1996). Other Tertiary map units in the park area 

include dunes, and shell-bearing sediments (Scott 2001). 

Shallow water limestone of the Fort Thompson 

Formation comprises the uppermost 17 m (55 ft) of 

cored section in the Everglades. This limestone is locally 

combined with the capping unit of the Miami Limestone. 

The Fort Thomson Formation grades laterally into the 

Key Largo Limestone to the east and west of the park 

(Cunningham 2005). The Fort Thompson Formation is 

mostly lagoonal facies carbonate with abundant bivalve 

fossils and some quartz sand. The Miami Limestone is 

125–130 thousand years old and records interglacial 

deposition. 

Overlying the Miami Limestone bedrock are surficial 

units of beach ridge and dunes, freshwater peat and 

organic muck, freshwater and marine marls, thin soils, 

and cyanobacteria mats (Scott 2001: Cunningham 2005). 

The peat and muck typically occur in low-lying sloughs 

and solution holes and are dark and fine-grained. During 

the standing water phase of the wet season, extracellular 

precipitation of calcium carbonate by cyanobacteria 

forms fresh and marine limestone marls. The marine 

marls (Flamingo Marl) are dominated by aragonitic 

(calcium carbonate) mud, and shell deposits that form a 

sort of coastal levee around the southern rim of the park 

(Cunningham 2005). 

Map units for Everglades National Park also include 

benthic habitats in Florida Bay as captured by aerial 

photogrammetry. Unconsolidated units include sand 

banks, sand, mixed fine seagrass areas, mud banks, and 

dredged muds. Some habitats were also delineated based 

on the degree of submerged aquatic vegetation and 

submerged rooted vascular plant cover. This cover 

ranged from non-existent, discontinuous, and dredged 

to continuous. Other habitats surveyed include land, 

reef, seagrass, and hardbottom types (FFWC 1999). 

 EVER Geologic Resource Evaluation Report 25 

Geologic History 

This section describes the rocks and unconsolidated deposits that appear on the digital 

geologic map of Everglades National Park, the environment in which those units were 

deposited, and the timing of geologic events that created the present landscape. 

The Florida platform is among the younger additions to 

the North American continent. Thousands of meters of 

interlayered carbonates and siliciclastics represent a 

predominantly stable depositional environment 

punctuated by erosional and high-energy events. The 

rocks deep below Florida give clues to its origin and 

geologic history (fig. 10). 

Late Paleozoic Era 

During the Mississippian, the landmass that now 

underlies the grand carbonate platform of Florida was 

not attached to the North American craton. It may have 

been attached to the northwest portion of the African 

continent (Condie and Sloan 1998). In any case, marine 

carbonates were deposited over large portions of the 

area atop a Paleozoic age crystalline basement high, the 

Peninsular Arch (Pollastro et al. 2000). 

In the Pennsylvanian, a collision event, known as the 

Ouachita orogeny sutured the Florida landmass to the 

continent as Gondwanaland and North America 

collided. This plate movement eventually formed the 

supercontinent Pangaea. Many north to northeast 

trending strike-slip and thrust faults were active, as a 

result of the multi-directional tectonic stresses at this 

time (Amsbury and Haenggi 1993). South Florida was 

completely submerged and located at the junction of the 

North American, South American, and African plates 

(fig. 11). Through the Permian, Pangaea remained intact 

(Condie and Sloan 1998). Highlands to the north of the 

Florida landmass eroded quickly when compressional 

tectonic forces subsided during the Permian. 

Early Mesozoic Era 

At the beginning of the Triassic Period, Pangaea began to 

break up (~220–245 Ma). During the late Triassic–

Jurassic periods, South and Central America and Africa 

began to rift away from North America. This established 

the long-standing passive margin of the eastern seaboard 

that persists today. The Florida and Cuba blocks 

detached from northwest Africa and the Gulf of Mexico 

opened (Condie and Sloan 1998). This created large 

basins for deposition of sediments shed from the rapidly 

eroding Ouachitan highlands. In the early stages, a series 

of discontinuous rift basins developed parallel to the 

edge of the opening ocean basin. These basins extended 

from Mexico to Nova Scotia (Hentz 2001). 

Accompanying the rifting of Pangaea was the widespread 

extrusion of volcanic rocks consistent with mantle plume 

upwelling due to crustal tension (Heatherington and 

Mueller 1991). This continental rifting also opened the 

Atlantic Ocean basin. 

Middle Mesozoic Era 

Underlying the south Florida basin are igneous rhyolitic–

basaltic rocks (Thomas et al. 1989). These rocks were 

sampled from a 5.7 km (3.5 mi) deep core in Collier 

County. Geochemical composition indicates they were 

formed within a mantle plume in a continental rifting 

environment consistent with the breakup of Pangaea. 

Geologists surmise a hotspot initiated local rifting off the 

southern tip of the Florida Platform (Heatherington and 

Mueller 1991; Cunningham 2005). 

These igneous rocks were subaerially exposed and 

eroded during the late Triassic to middle Jurassic. 

Deposits of sands and silts covered local areas, which 

upon exposure formed redbeds. Accompanying the 

opening of the proto-Atlantic Ocean, the Caribbean 

basin, and the ancestral Gulf of Mexico were major 

lateral displacements along transform faults such as the 

North Bahamas fracture zone (Condie and Sloan 1998). 

During the late Jurassic the Atlantic Ocean and 

Caribbean basin continued to develop, depositing deltaic 

and shallow marine sediments over the Florida Platform. 

Restriction of marine circulation at this time resulted in 

periodic accumulations of evaporites and marine 

carbonates (Cunningham 2005). Deposition of Jurassic 

and Cretaceous sediments was controlled by the southsoutheast plunging axis of the Peninsular Arch. Basal 

sediments onlap and pinch out against the arch 

(Pollastro et al. 2000). 

Late Mesozoic Era 

As sea level rise proceeded during the early Cretaceous, 

the Florida Platform was the site of more widespread 

deposition of marine limestones and reefs. Reef 

distribution was clustered along the margin of the 

ancestral Gulf of Mexico and the edges of the Florida 

Platform (Cunningham 2005). From the Middle 

Cretaceous to the Late Paleogene, the Suwannee Strait 

(often called the Gulf Trough) separated the carbonate 

Florida Platform from a clastic shelf and slope that was 

developing along the southeastern margin of North 

America. These clastics originated from the eroding 

Appalachian Mountains. Currents running through the 

strait prevented the clastics from interrupting the 

continuous accumulation of carbonates on the Florida 

platform. As currents changed and the seaway was 

infilled, by the late Eocene, some of the siliciclastics were 

mixed with the deep carbonate sediments (Cunningham 

et al. 2003). 

Further transgression and global warming during the 

Late Cretaceous established an open marine 

accumulation of carbonates over the entire Florida 

Peninsula. Accompanying this widespread accumulation 
26 NPS Geologic Resources Division 

was the development of reefal deposition of rudistid 

bivalves around the southern margin of the Florida area. 

By the Late Cretaceous, the Gulf of Mexico was 

completely open. The new crust formed by igneous 

extrusion during extension was now the ProtoCaribbean tectonic plate. This oceanic crust separates 

the Gulf of Mexico and the Yucatan from South 

America. At this time, the Antilles arc (portions of which 

now comprise parts of Hispaniola and Puerto Rico) 

moved eastward and began subducting beneath the Cuba 

Block (Condie and Sloan 1998). 

Cenozoic Era 

Cenozoic development of the Florida Platform included 

additional deposition of marine carbonates and 

deposition of siliciclastics from northwestern highlands 

sources and long shore oceanic currents. Tertiary 

faulting occurred south of Florida as the Cuban block 

continued to collide with the Antilles arc and carbonate 

accumulation continued in Florida (Condie and Sloan 

1998). In southern Florida, the open marine depositional 

setting continued during the Paleocene as more 

restricted flow to the north resulted in deposits of mixed 

carbonates and intermittent evaporites (during restricted 

marine conditions). Eocene and Oligocene deposition is 

marked by shallow water carbonates. Intermittent with 

this deposition were subaerial exposures forming 

erosional surfaces and scant redbeds associated with 

local oceanic regressions. 

Deposition in south Florida during the Miocene changed 

with the introduction of more widespread siliciclastics 

from a fluvio-deltaic system prograding down the 

peninsula. These deposits were derived from the rapidly 

eroding southern Appalachian Mountains as the Atlantic 

Coastal Plain physiographic province continued to 

develop eastward. Phosphates and the carbonate ramp of 

the Arcadia Formation were deposited during the 

Miocene in southeastern Florida (Cunningham 2005). 

Siliciclastic deposits comprising the Peace River 

Formation then buried this carbonate ramp in the 

Miocene. Marine upwelling at this time is responsible for 

the diatomaceous mudstones and high organic 

productivity represented by the lower beds of the Peace 

River Formation (Cunningham et al. 1998). 

Some of the Miocene siliciclastic deposits of the Peace 

River Formation were eroded and reworked during a 

marine regression. This Pliocene lowstand caused a 

disconformity between the Peace River and overlying 

Long Key Formation. South of Everglades National Park, 

the Peace River Formation is absent – either never 

deposited or eroded away completely. During the 

Pliocene, the Everglades area was the focus of deposition 

of a thick pile of sand eroded from the Miocene deposits 

that was being transported south to eventually form the 

Long Key Formation (Guertin et al. 1999; Cunningham 

2005). This wedge of sand covered the area that is now 

Everglades National Park and extended as far south as 

the Florida Keys. Deposition was in fluctuating outer and 

inner shelf conditions with depths ranging from 

150–180 m (~500–600 ft) to 10–50 m (~30–150 ft), 

respectively (Guertin et al. 1999). 

In addition to Pliocene siliciclastic deposition, local 

carbonate accumulations also occurred in south Florida. 

In the western reaches of the peninsula, was a midPliocene reef environment. Near the lower Florida Keys 

and the southwest Florida shelf, the coeval carbonates of 

the Stock Island Formation were deposited. These 

sediments were perhaps associated with currents 

originating in the Gulf of Mexico, flowing eastward 

through the Straits of Florida (Cunningham et al. 1998; 

Cunningham 2005). 

The Pleistocene Epoch is known for numerous extensive 

glacial events, which alternated with warmer interglacial 

stages. Although glacial ice never extended as far south as 

Florida, the accompanying global-scale climatic and sea 

level shifts played a major role in the formation of the 

geologic units and the overall landscape exposed today at 

Everglades National Park. The Pleistocene resulted in 

the conversion from siliciclastic deposition mixed with 

carbonate accumulation to more widespread carbonate 

sedimentation with occasional, localized siliciclastic 

contributions (Cunningham 2005). Global sea-level 

changes during the intermittent glacial/interglacial stages 

of the Pleistocene controlled the rate and distribution of 

carbonate units. 

During the last interglacial period (120–130 thousand 

years), mixed carbonate-siliciclastic sediments formed 

the Fort Thompson Formation. Deposition occurred in a 

restricted lagoonal environment (rich in marine fossil 

remains) during minor fluctuations in sea level. This unit 

interfingers with the surficial geologic units, the Miami 

and Key Largo Limestones, and the Anastasia Formation 

(~130 thousand years) (Cunningham 2005). 

The eastern areas of Everglades National Park contain 

exposures of the oolitic facies of the Miami Limestone. 

This unit is comprised of oolitic and pelloidal carbonate 

sands. These deposits grade westward into a lower 

energy, more restricted, bryozoan facies of the unit. 

Throughout the park area, the surface exposures of 

Miami Limestone contain a mixture of bryozoan 

remains, ooids, and lime peloids (Cunningham 2005). 

Sea level began to rise rapidly15–16 thousand years ago 

and by 6–7 thousand years ago southern Florida was 

extensively flooded (Shinn et al. 1997). Since that time 

sea level has continued to rise. Holocene geologic activity 

in the Everglades area consists of the pervasive 

dissolution of carbonate bedrock units, the surficial 

accumulation of carbonate muds, marine and freshwater 

marls, sands, and swamp deposits. Holocene sediment 

distribution is controlled by the geology, sea level, 

climate, and vegetation patterns (Cunningham 2005). 

In lower sloughs and solution holes, deposition of 

organic muck and peat soils dominates (Craighead 1971). 

Freshwater marl and cyanobacteria mats dominate the 

open prairies and deeper sloughs where calcium 

carbonate precipitates in situ covering the ground and 

vegetation (fig. 12). Marine marls dominate the coastal 

areas of Florida Bay. Flood events are responsible for the 

formation of these natural levees composed of aragonitic 

mud and shell fragments (Cunningham 2005). 
 EVER Geologic Resource Evaluation Report 27 

Figure 10: Geologic time scale; adapted from the U.S. Geological Survey (http://pubs.usgs.gov/fs/2007/3015/). Red lines indicate major 

unconformities between eras. Included are major events in life history and tectonic events occurring on the North American continent. 

Absolute ages shown are in millions of years. 
28 NPS Geologic Resources Division 

Figure 11: Evolution of the landscape in the Florida Platform area from the Mississippian-Pennsylvanian Ouachita orogeny through the 

Triassic-Jurassic extensional event opening the Gulf of Mexico, the Caribbean Sea, and the Atlantic Ocean. The Florida landmass sutured to 

the North American continent at this time. Diagram is not to scale. Graphic is by Trista L. Thornberry-Ehrlich (Colorado State University). 
 EVER Geologic Resource Evaluation Report 29 

Figure 12: Freshwater limestone marl coating the surface of the ground and vegetation in a open prairie area at Everglades National Park. 

Photograph is by Trista L. Thornberry-Ehrlich (Colorado State University). 
30 NPS Geologic Resources Division 

Glossary 

This glossary contains brief definitions of technical geologic terms used in this report. Not all 

geologic terms used are referenced. For more detailed definitions or to find terms not listed 

here please visit: http://wrgis.wr.usgs.gov/docs/parks/misc/glossarya.html. 

aquifer. Rock or sediment that is sufficiently porous, 

permeable, and saturated to be useful as a source of 

water. 

aragonitic. Pertaining to the mineral aragonite (CaCO3). 

asthenosphere. Weak layer in the upper mantle below 

the lithosphere where seismic waves are attenuated. 

axis (fold). A straight line approximation that when 

moved parallel to itself generates the shape of a fold 

(see and use hingeline) 

barchan dune. A crescent-shaped dune with arms or 

horns of the crescent pointing downwind. The 

crescent or barchan type is most characteristic of the 

inland desert regions. 

barrier island. A long, low, narrow island formed by a 

ridge of sand that parallels the coast. 

basement. The undifferentiated rocks, commonly 

igneous and metamorphic, that underlie the rocks of 

interest. 

basin (structural). A doubly-plunging syncline in which 

rocks dip inward from all sides. 

basin (sedimentary). Any depression, from continental 

to local scales, into which sediments are deposited. 

beach. A gently sloping shoreline covered with sediment, 

often formed by action of waves and tides. 

bed. The smallest sedimentary strata unit, commonly 

ranging in thickness from one centimeter to a meter or 

two and distinguishable from beds above. 

bedding. Depositional layering or stratification of 

sediments. 

calcareous. A rock or sediment containing calcium 

carbonate. 

cementation. Chemical precipitation of material into 

pores between grains that bind the grains into rock. 

chemical sediment. A sediment precipitated directly 

from solution (also called nonclastic). 

chemical weathering. The dissolution or chemical 

breakdown of minerals at Earth’s surface via reaction 

with water, air, or dissolved substances. 

clastic. Rock or sediment made of fragments or preexisting rocks. 

clay. Clay minerals or sedimentary fragments the size of 

clay minerals (<2 cm). 

conglomerate. A coarse-grained sedimentary rock with 

clasts larger than 2 mm in a fine-grained matrix. 

continental crust. The type of crustal rocks underlying 

the continents and continental shelves; having a 

thickness of 25–60 km (16–37 mi) and a density of 

approximately 2.7 grams per cubic centimeter. 

continental rise. Gently sloping region from the foot of 

the continental slope to the abyssal plain. 

continental shelf. The shallowly-submerged portion of a 

continental margin extending from the shoreline to the 

continental slope with water depths of less than 200 m 

(656 ft). 

continental slope. The relative steep slope from the 

outer edge of the continental shelf down to the more 

gently sloping ocean depths of the continental rise or 

abyssal plain. 

convergent boundary. A plate boundary where two 

tectonic plates are moving together (i.e., a zone of 

subduction or obduction). 

craton. The relatively old and geologically stable interior 

of a continent. 

cross-bedding. Uniform to highly-varied sets of inclined 

sedimentary beds deposited by wind or water that 

indicate distinctive flow conditions. 

cross section. A graphical interpretation of geology, 

structure, and/or stratigraphy in the third (vertical) 

dimension based on mapped and measured geological 

extents and attitudes depicted in an oriented vertical 

plane. 

crust. The outermost compositional shell of Earth, 10–40 

km (6–25 mi) thick, consisting predominantly of 

relatively low-density silicate minerals (also see 

oceanic crust and continental crust). 

crystalline. Describes the structure of a regular, orderly, 

repeating geometric arrangement of atoms 

deformation. A general term for the process of faulting, 

folding, shearing, extension, or compression of rocks 

as a result of various Earth forces. 

delta. A sediment wedge deposited at a stream’s mouth 

where it flows into a lake or sea. 

dip. The angle between a structural surface and a 

horizontal reference plane measured normal to their 

line of intersection. 

disconformity. An unconformity at which the bedding of 

the strata above and below are parallel. 

divergent boundary. A tectonic plate boundary where 

the plates are moving apart (e.g., a spreading ridge or 

continental rift zone). 

dune. A low mound or ridge of sediment, usually sand, 

deposited by wind. Common dune types include the 

barchan dune, longitudinal dune, parabolic dune, and 

transverse dune (see respective listings). 

eolian. Formed, eroded, or deposited by or related to the 

action of the wind. 

estuary. The seaward end or tidal mouth of a river where 

fresh and sea water mix. Many estuaries are drowned 

river valleys caused by sea level rise (transgression) or 

coastal subsidence. 

evaporite. Chemically precipitated mineral(s) formed by 

the evaporation of solute-rich water under restricted 

conditions. 

facies (sedimentary). The depositional or environmental 

conditions reflected in the sedimentary structures, 

textures, mineralogy, fossils, etc. of a sedimentary 

rock. 

fault. A subplanar break in rock along which relative 

movement occurs between the two sides. 
 EVER Geologic Resource Evaluation Report 31 

formation. Fundamental rock-stratigraphic unit that is 

mappable and lithologically distinct from adjoining 

strata and has definable upper and lower contacts. 

fracture. Irregular breakage of a mineral; also any break 

in a rock (e.g., crack, joint, fault) 

igneous. Refers to a rock or mineral that originated from 

molten material that is one of the three main classes or 

rocks—igneous, metamorphic, and sedimentary. 

joint. A semi-planar break in rock without relative 

movement of rocks on either side of the fracture 

surface. 

karst topography. Topography characterized by 

abundant sinkholes and caverns formed by the 

dissolution of calcareous rocks. 

lacustrine. Pertaining to, produced by, or inhabiting a 

lake or lakes. 

levees. Raised ridges lining the banks of a stream; may be 

natural or artificial. 

lineament. Any relatively straight surface feature that can 

be identified via observation, mapping, or remote 

sensing, often representing tectonic features. 

lithification. The conversion of sediment into solid rock. 

lithology. The description of a rock or rock unit, 

especially the texture, composition, and structure of 

sedimentary rocks. 

lithosphere. The relatively rigid outmost shell of Earth’s 

structure, 50 to 100 km (31 to 62 mi) thick that 

encompasses the crust and uppermost mantle. 

longitudinal dunes. Dunes elongated parallel to the 

direction of wind flow. 

longshore current. A current parallel to a coastline 

caused by waves approaching the shore at an oblique 

angle. 

mantle. The zone of the Earth’s interior between crust 

and core. 

marl. A loose earthy deposit made up of a mixture of clay 

and calcium carbonate, formed under marine or 

freshwater conditions. 

matrix. The fine-grained interstitial material between 

coarse grains in porphyritic igneous rocks and poorly 

sorted clastic sediments or rocks. 

mechanical weathering. The physical breakup of rocks 

without change in composition (syn: physical 

weathering). 

member. A lithostratigraphic unit with definable contacts 

that subdivides a formation. 

obduction. The process by which the crust is thickened 

by thrust faulting at a convergent margin. 

oceanic crust. Earth’s crust formed at spreading ridges 

that underlies the ocean basins. Oceanic crust is 6–7 

km (3–4 mi) thick and generally of basaltic 

composition. 

ooid. A small, spheroidal, layered sedimentary grain, 

usually composed of calcium carbonate. Ooids usually 

form on the sea floor, most commonly in shallow 

tropical seas. 

orogeny. A mountain-building event, particularly a wellrecognized event in the geological past (e.g. the 

Ouachita orogeny). 

outcrop. Any part of a rock mass or formation that is 

exposed or “crops out” at Earth’s surface. 

paleontology. The study of the life and chronology of 

Earth’s geologic past based on the phylogeny of fossil 

organisms. 

paleosol. A preserved soil that formed on a landscape in 

the past with distinctive features resulting from an 

environment that no longer exists at the site. 

Pangaea. A theoretical, single supercontinent that 

existed during the Permian and Triassic Periods (also 

see Laurasia and Gondwana). 

parabolic dunes. Crescent-shaped dunes with horns or 

arms that point upwind. 

parent (rock). The original rock from which a 

metamorphic rock or soil was formed. 

passive margin. A tectonically quiet continental margin 

indicated by little volcanic or seismic activity. 

pebble. Generally, small, rounded, rock particles from 4 

to 64 mm in diameter. 

permeability. A measure of the ease or rate that fluids 

move through rocks or sediments. 

plate tectonics. The theory that the lithosphere is broken 

up into a series of rigid plates that move over Earth’s 

surface above a more fluid asthenosphere. 

porosity. The proportion of void space (cracks, 

interstices) in a volume of a rock or sediment. 

regression. A long-term seaward retreat of the shoreline 

or relative fall of sea level. 

rift basin. A depression formed by grabens along the 

crest of an oceanic spreading ridge or in a continental 

rift zone. 

sandstone. Clastic sedimentary rock of predominantly 

sand-sized grains. 

sediment. An eroded and deposited, unconsolidated 

accumulation of lithic and mineral fragments. 

sedimentary rock. A consolidated and lithified rock 

consisting of detrital and/or chemical sediment(s). 

sequence. A major informal rock-stratigraphic unit that 

is traceable over large areas and defined by a major sea 

level transgression-regression sediment package. 

siliciclastics. Pertaining to clastic noncarbonated rocks 

composed almost exclusively of quartz (or other 

silicate) grains. 

silt. Clastic sedimentary material intermediate in size 

between fine-grained sand and coarse clay (1/256–1/16 

mm). 

siltstone. A variable-lithified sedimentary rock with siltsized grains. 

slope. The inclined surface of any geomorphic feature or 

rational measurement thereof (syn: gradient). 

soil. Surface accumulation of weathered rock and 

organic matter capable of supporting plant growth and 

often overlying the parent rock from which it formed. 

spring. A site where water flows out at the surface due to 

the water table intersecting the ground surface. 

strata. Tabular or sheetlike masses or distinct layers (e.g., 

of rock). 

stratigraphy. The geologic study of the origin, 

occurrence, distribution, classification, correlation, 

age, etc. of rock layers, especially sedimentary rocks. 

strike. The compass direction of the line of intersection 

that an inclined surface makes with a horizontal plane. 

strike-slip fault. A fault with measurable offset where the 

relative movement is parallel to the strike of the fault. 

subduction zone. A convergent plate boundary where 

oceanic lithosphere descends beneath a continental or 

oceanic plate and is carried down into the mantle. 

subsidence. The gradual sinking or depression of part of 

Earth’s surface. 
32 NPS Geologic Resources Division 

suture. The linear zone where two continental 

landmasses become joined due to obduction. 

tectonic. Relating to large-scale movement and 

deformation of Earth’s crust. 

terraces (stream). Step-like benches surrounding the 

present floodplain of a stream due to dissection of 

previous flood plain(s), stream bed(s), and/or valley 

floor(s). 

terrestrial. Relating to Earth or Earth’s dry land. 

thrust fault. A contractional, dip-slip fault with a 

shallowly dipping fault surface (<45o

) where the 

hanging wall moves up and over relative to the 

footwall. 

topography. The general morphology of Earth’s surface 

including relief and location of natural and 

anthropogenic features. 

transgression. Landward migration of the sea due to a 

relative rise in sea level. 

transverse dunes. Dunes elongated perpendicular to the 

prevailing wind direction. The leeward slope stands at 

or near the angle of repose of sand whereas the 

windward slope is comparatively gentle. 

trend. The direction or azimuth of elongation or a linear 

geological feature. 

unconformity. A surface within sedimentary strata that 

marks a prolonged period of nondeposition or 

erosion. 

volcanic. Related to volcanoes; describes igneous rock 

crystallized at or near Earth’s surface (e.g., lava). 

water table. The upper surface of the saturated (phreatic) 

zone. 

weathering. The set of physical, chemical, and biological 

processes by which rock is broken down in place. 
 EVER Geologic Resource Evaluation Report 33 

References 

This section lists references cited in this report as well as a general bibliography that may 

be of use to resource managers. A more complete geologic bibliography is available from 

the National Park Service Geologic Resources Division. 

Amsbury, D. L., W. T. Haenggi. 1993. Middle 

Pennsylvanian strike-slip faulting in the Llano Uplift, 

central Texas. Bulletin of the South Texas Geological 

Society 34 (1): 9-16. 

Bosence, D. W. J. 1995. Anatomy of a Recent biodetrital 

mud-mound, Florida Bay, USA. Special Publications of 

the International Association of Sedimentologists 23: 

475-493. 

Brewster-Wingard, L. 2001. Ecosystem History: Florida 

Bay and the Southwest Coast. U.S. Geological Survey. 

http://sofia.usgs.gov/projects/eh_fbswc/ (accessed 

February 28, 2006). 

Brooks, H. K. 1981. Physiographic Divisions map of 

Florida. University of Florida Institute of Food and 

Agricultural Sciences, Center for Environmental and 

Natural Resources. 

Bruno, M. C., K. J. Cunningham, S. A. Perry. 2003. 

Copepod Communities from Surface and Ground 

Waters in the Everglades, South Florida. Southeastern 

Naturalist 2(4): 523-546. 

Condie, K. C., R. E. Sloan. 1998. Origin and Evolution of 

the Earth, Principles of Historical Geology. PrenticeHall, Inc. 

Craighead, F. C., Sr. 1971. The Trees of South Florida, 

Vol. 1, The Natural Environment and their Succession. 

Coral Gables, FL: University of Miami Press. 

Crisfield, E., D. Greco, M. Martin, L. York. 2005. 

Memorandum re: December 13-15-2004 Site Visit – 

Evaluation of Restoration Alternatives for the Cape 

Sable Canals at Everglades National Park (EVER). 

National Park Service, unpublished. 

Cunningham, K. J. 2005. Hydrogeologic Fieldtrip 

Everglades National Park, Southeastern Florida, 

unpublished. 

Cunningham, K. J. 2004a. Application of groundpenetrating radar, digital optical borehole images, and 

cores for characterization of porosity hydraulic 

conductivity and paleokarst in the Biscayne aquifer, 

southeastern Florida, USA. Journal of Applied 

Geophysics 55: 61-76. 

Cunningham, K. J. 2004b. New method for 

quantification of vuggy porosity from digital optical 

borehole images as applied to the karstic Pleistocene 

limestone of the Biscayne aquifer, southeastern 

Florida. Journal of Applied Geophysics 55: 77-90. 

Cunningham, K. J., S. D. Locker, A. C. Hine, D. Burky, J. 

A. Barron, L. A. Guertin. 2003. Interplay of Late 

Cenozoic Siliciclastic Supply and Carbonate Response 

on the Southeast Florida Platform. Journal of 

Sedimentary Research 73 (1): 31-46. 

Cunningham, K. J., D. F. McNeill, L. A. Guertin, P. F. 

Ciesielski, T. M. Scott, L. de Verteuil. 1998. New 

Tertiary Stratigraphy for the Florida Keys and 

Southern Peninsula of Florida. Geological Society of 

America Bulletin 110: 231-258. 

FDEP. 2005. About the Everglades. Florida Department of 

Environmental Protection. 

http://www.dep.state.fl.us/secretary/ps/default.htm 

(accessed February 20, 2008). 

FFWC. 1999. Benthic Habitats of Florida Bay, FL 1991-

1995. Florida Fish and Wildlife Commission Florida 

Marine Research Center – National Oceanic and 

Atmospheric Administration Coastal Services Center. 

CD-ROM 1:48,000. 

FGS. 2005. Sinkholes. Florida Geological Survey, Florida 

Department of Environmental Protection. 

http://www.dep.state.fl.us/geology/geologictopics/sink

hole.htm (accessed February 24, 2006). 

FLNHM. 2006. Florida Bay. Florida Museum of Natural 

History. 

http://www.flmnh.ufl.edu/fish/southflorida/FloridaBa

y.html (accessed February 28, 2006) 

Guertin, L. A., D. F. McNeill, B. H. Lidz, K. J. 

Cunningham. 1999. Chronology and 

Transgressive/Regressive Signatures in the Late 

Neogene Siliciclastic Foundation (Long Key 

Formation) of the Florida Keys. Journal of Sedimentary 

Research 69: 653-666. 

Heatherington, A. L., P. A. Mueller. 1991. Geochemical 

evidence for Triassic rifting in southwestern Florida. 

Tectonophysics 188:291-302. 

Hentz, T. F. 2001. Geology. In: The handbook of Texas. 

University of Texas at Austin, 

http://www.tsha.utexas.edu/handbook/online/articles/

GG/swgqz.html (accessed February 28, 2006). 

Hickey, D. 2005. Rock Reef Pass – the Mystery of the 

Rock Ridges. In Hydrogeologic Fieldtrip Everglades 

National Park, Southeastern Florida, Cunningham, K.J. 

unpublished. 
34 NPS Geologic Resources Division 

Hoffmeister, J. E., K. W. Stockman, H. G. Multer. 1967. 

Miami Limestone of Florida and its recent Bahamian 

counterpart. Geological Society of America Bulletin 78: 

175-190. 

Hoffmeister, J. E. 1974. Land from the sea – The geologic 

story of south Florida. Coral Gables, FL: University of 

Miami Press. 

Holmes, C. W., R. Miller. 2004. Atmospherically 

transported elements and deposition in the 

Southeastern United States: local or transoceanic? 

Applied Geochemistry 19: 1189-1200. 

IGS. 2006. Aquifer Definitions – Some useful definitions 

for talking intelligently about aquifers. Idaho 

Geological Survey. http://www.idahogeology.org/ 

(accessed February 24, 2006). 

Kruse, S. E., J. C. Schneider, D. J. Campagna, J. A. Inman, 

T. D. Hickey. 2000. Ground penetrating radar imagine 

of cap rock, caliche and carbonate strata. Journal of 

Applied Geophysics 43: 239-249. 

Loftus, W. F., M. C. Bruno, K. J. Cunningham, S. A. 

Perry, J. C. Trexler. 2001. The Ecological Role of the 

Karst Wetlands of Southern Florida in Relation to 

System Restoration. U.S. Geological Survey, Water 

Resources Investigations WRI 01-4011. 

McNeill, D. F., K. J. Cunningham, L. A. Guertin, L. A. 

Melim, E. R. Warzeski, F. S. Anselmetti, R. N. 

Ginsburg, G. P. Eberli, P. K. Swart. 1996. Data Report: 

Tertiary-Quaternary cores from the Florida Keys and 

Everglades. South Miami, Florida: Miami Geological 

Society. 

McPherson, B. F., C. Y. Hendrix, H. Klein, H. M. Tyus. 

1976. The Environment of South Florida, A summary 

Report. U.S. Geological Survey, Professional Paper

1011. 

NOAA. 2006. Outreach – South Florida Ecosystem 

Education Project. U.S. Department of Commerce, 

National Oceanic and Atmospheric Administration 

http://www.commerce.gov/ 

http://www.aoml.noaa.gov/sfp/outreach.shtml 

(accessed February 28, 2006). 

Pollastro, R. M., C. J. Schenk, R. R. Charpenter. 2000. 

Undiscovered Oil and Gas in the Big Cypress National 

Preserve—A Total Petroleum System Assessment of 

the South Florida Basin, Florida. U.S. Geological 

Survey, Open File Report: 00-317. 

Prager, E., R. Halley. 1997. Florida Bay Bottom Types. 

U.S. Geological Survey, Open File Report 97-256. 

Scott, T. M. 2001. Geologic Formations of Florida. Florida 

Geological Survey digital file, 1:126,720. 

http://www.dep.state.fl.us/geology/gisdatamaps/state_

geo_map.htm (accessed February 26, 2006). 

SFWMD. 2002. The Living Everglades. The South Florida 

Water Management District. 

http://glades.sfwmd.gov/empact/home/index.shtml 

(accessed March 3, 2006). 

Shinn, E. A., B. H. Lidz, R. B. Halley. 1997. IGC Field 

Guide T176: A Field Guide: Reefs of Florida and the 

Dry Tortugas. In Geological Environments of Florida 

Bay and the Florida Keys Reef Tract, comp. Tihansky, 

A., Prager, E., and Shinn, G. 

Steinen, R. P., E. A. Shinn, R. B. Halley. 1995. 

Hypothesized fault origin for the rock reefs of South 

Florida. Abstracts with Programs – Geological Society of 

America 27 (6): 229. 

Thomas, W. A., T. M. Chowns, D. L. Daniels, T. L. 

Neatherly, L. Glover, R. J. Gleason. 1989. The 

subsurface Appalachians beneath the Atlantic and Gulf 

coastal plains. In The Geology of North America F-2, 

Geological Society of America. 

Warzeski, E. R., K. J. Cunningham, R. N. Ginsburg, J. B. 

Anderson, Z. D. Ding. 1996. Neogene Mixed 

Siliciclastic and Carbonate Foundation for the 

Quaternary Carbonate Shelf, Florida Keys. Journal of 

Sedimentary Research 66: 788-800. 
 EVER Geologic Resource Evaluation Report 35 

Appendix A: Geologic Map Graphic 

The following page is a preview or snapshot of the geologic map for Everglades National 

Park. For a poster-size PDF of this map or for digital geologic map data, please see the 

included CD or visit the Geologic Resource Evaluation publications Web page 

(http://www.nature.nps.gov/geology/inventory/gre_publications.cfm). 

 EVER Geologic Resource Evaluation Report 37 

Appendix B: Scoping Summary 

The following excerpts are from the GRE scoping summary for Everglades National 

Park. The scoping meeting was on January 24–25, 2005; therefore, the contact 

information and Web addresses referred to in this appendix may be outdated. Please 

contact the Geologic Resources Division for current information. For the full scoping 

summary, please visit the GRE publications Website 

(http://www.nature.nps.gov/geology/inventory/gre_publications.cfm). 

Executive Summary 

A Geologic Resources Evaluation scoping meeting took 

place in Homestead, Florida on January 24, 2005. The 

meeting was followed by a field trip on January 25, 2005. 

The scoping meeting participants identified the 

following list of geologic resource management issues. 

These topics are discussed in detail below. 

1. The Florida Bay mud banks elevation and stability 

2. Mangrove zone topography and buttonwood ridge 

height 

3. Whitewater Bay and Gulf Coast estuaries 

4. Solution holes 

5. Aquifer characteristics and groundwater flow 

dynamics 

6. Recreation and other use demands 

7. Earthen and failed dams, canals, and sheet piling 

8. Sediment transport and resuspension at Lake 

Ingraham 

9. Sinkholes and karst features 

10. Paleoclimates 

11. Sea level rise 

12. Geologic changes due to storms and hurricanes 

13. Atmospheric deposition of African dust 

14. “Lake Belt” management 

15. Tree islands and hardwood hammacks 

16. Archaeological sites 

Introduction 

The National Park Service held a Geologic Resource 

Evaluation scoping meeting for Everglades National Park 

at the Krome Center in Homestead, Florida on Monday, 

January 24, 2005, followed by a field trip the next day. 

The purpose of the meeting was to discuss the status of 

geologic mapping in the park, the associated 

bibliography, and the geologic issues in the park. 

The products to be derived from the scoping meeting 

are: (1) Digitized geologic maps covering the park; (2) An 

updated and verified bibliography; (3) Scoping summary 

(this report); and (4) A Geologic Resource Evaluation 

Report which brings together all of these products. 

Everglades National Park was established under Harry S. 

Truman’s administration on December 6, 1947. On 

October 26, 1976, the park was designated as an 

International Biosphere Reserve. The park attained its 

Wilderness Designation on November 10, 1978. It was 

made a world heritage site on October 24, 1979, and was 

named a Wetland of International Importance on June 4, 

1987. Everglades covers 1,508,537 acres spanning the 

southern tip of the Florida peninsula and most of Florida 

Bay between the peninsula and the Florida Keys. The 

Everglades is the only subtropical preserve in North 

America. The environments at the park vary from 

mangrove and cypress swamps, marine and estuarine 

environments, pinelands and hardwood hammocks, 

sawgrass prairies and rock ridges. The area includes a 

large portion of the Florida Bay, a large carbonate mud 

bank. The park contains some of the most pristine and 

unique marshland habitat in the continental United 

States. 

Everglades National Park identified 385 quadrangles of 

interest. The Florida State Geologic Survey (FGS) has 

digitized a geologic map covering the state from 

individual county maps at a small scale (~ 1: 126,720 or 

larger). This map only displays 4 separate geologic units 

(Holocene sediments, Key Largo Limestone, Miami 

Limestone, Tamiami Formation) for inside the 

boundaries of the park. Located within the quadrangles 

of interest are 11 additional geologic map units. 

Other geologic maps covering portions of the park itself 

include the FGS MS6/22 (1:24,000, 2000), the benthic 

habitat map published by NOAA CSC (1:48,000, 1999), 

Geological Society of America (GSA) Memoir 147 

(1:79,000, 1977), the FGS OFMS 83/01-07 (1:100,000, 

1996), 83/08-12 (1:100,000, 1995), 67 (1:26,720, Dade 

County), 66/01 (1:26,720, Monroe County), 63 and Series 

120 (1:26,720, Collier County), USGS OF 97-526 

(1:120,000, 1997) and 86-4126 (1:136,000, 1986). BEM 

Systems produced a hydrostratigraphy study for Big 

Cypress National Preserve and a small portion of the 

Everglades National Park that shows interpolated depth 

to the tops and bottoms of aquifer and aquitard layers. 

Additional mapping at a smaller scale will be more 

helpful for park management. 

Significant Geologic Resource Management Issues at 

Everglades National Park 

The Florida Bay mud banks elevation and stability 

The Florida Bay is covered by an extensive system of 

supra- and subtidal carbonate mud banks, coastal marl 

ridges, coastal carbonate mud ridges, mangrove peat 

deposits, and mollusk deposits. There is a strong 

resource management need to understand how water 

moves around the bay and what buttressing effect, if any, 

the mud and marl ridges have on the flow of water. 

Another concern is gaining an understanding of the 

nature of landscape evolution during late Holocene sea 
38 NPS Geologic Resources Division 

level rise (23 cm [9 in] rise in sea level in 70 years). Many 

of the freshwater marshes behind the ridges are changing 

to super saline marine lagoons. The features in the bay 

are strongly related to minute changes in elevation. 

Environments can change within centimeters of 

topographic relief. Given the coverage of mapping at the 

park, normal surficial maps are not sufficient for 

complex management decisions at the Everglades. An 

interdisciplinary approach to mapping is critical to 

producing a useful product for resource management. 

Anthropogenic, supratidal, intertidal, subtidal, and 

coastal features would all be helpful. This holistic 

ecosystem approach integrates biological, physical, 

cultural, and oceanographic parameters. Lidar surveys in 

addition to satellite imagery, multibeam mapping, 

bathymetry data, water quality and circulation, shoreline 

change data, pre- and post-storm comparisons, 

oceanographic data (waves, tides, currents, turbidity, 

temperature salinity, sediment transport patterns, coral 

larvae and other species distributions), etc. are essential 

for resource management at Everglades National Park. 

Research and monitoring questions and suggestions 

include: 

• What is the relationship between coastal marl and 

carbonate mud ridges and the buttonwood 

distribution? 

• What is the minimum mapping unit relevant to 

resource management? 

• What are the flow dynamics (especially related to 

salinity) in the bay? 

• What controls the distribution of the mud banks? 

• Is there any remediation possible for the hypersaline 

environment in the central portion of the bay? 

• Why does the basin and bank character of the Florida 

Bay resemble hexagonal mudcracks? 

Mangrove zone topography and buttonwood ridge height 

Mangroves thrive in oscillating fresh-saline water 

conditions. In a sense, they define the water level. A 

baseline needs to be established regarding sea level rise 

to determine its effect on the mangrove areas. Detailed 

topography would help manage this resource. The scale 

of inches is important for the low banks and ridges where 

the tides and wind expose the entire western basins. 

Whitewater Bay and Gulf Coast estuaries 

Whitewater Bay sits behind Cape Sable and is fed by the 

Shark, Broad, and Harney Rivers. It is bound by a 

buttonwood embankment growing as a natural berm on 

a storm beach made of mud. 

Research and monitoring questions and suggestions 

include: 

• What is the relationship between the diversion of 

water through canals and the buttonwood 

distribution? 

• What is the nature of the Shark Slough-Taylor Slough 

divide? 

Solution holes 

Solution holes are an element of the karst topography at 

the park. They provide essential habitat for fish and 

other wildlife during the dry winter months at the 

Everglades. Solution holes occur throughout the park 

(especially in the eastern half) and need to be 

systematically located, mapped, and described for 

resource management. 

Research and monitoring questions and suggestions 

include: 

• How are solution holes and other karst features 

affecting water quality at the Everglades? 

• Are solution holes sources of phosphorus input? 

• How do solution holes affect the hydrogeologic regime 

including retention time, hydraulic head, and water 

storage? 

• What is the relationship between water quality and 

karst topography? 

Aquifer characteristics and groundwater flow dynamics 

The interaction between groundwater flow and the 

overall fresh water and marine ecological quality must be 

quantitatively determined at the Everglades. Visitor uses 

and surrounding development are increasing the levels of 

certain substances in the water at the park. Nutrients 

from waste are causing algal blooms. Salinity levels are 

dependent on seasonal freshwater input and tidal 

circulation in the Florida Bay. 

Research and monitoring questions and suggestions 

include: 

• How many wells are necessary to model the 

hydrogeologic system at the park? 

• Model the porosity and permeability of the Fort 

Thompson Formation. 

• Examine the salt wedge characteristics versus the 

surface water. 

• Is increasing the hydraulic head at the Everglades a 

good idea? 

• How would an increase in hydraulic head from either 

concentrated precipitation or anthropogenic 

interference affect the local spring activity? 

Recreation and other use demands 

In 2004, Everglades National Park hosted 1,374,789 

visitors, placing increasing demands on the limited 

resources and fragile ecosystem of the park. Motorized 

boat access and fishing are restricted in the wilderness 

areas of the park. 

Research and monitoring questions and suggestions 

include: 

• Are visitors affecting sediment transport and the 

hydrologic system at the park? 

Earthen and failed dams, canals, and sheet piling 

Dams and other earth works in the park pose a serious 

threat to the safety of visitors and park resources. During 
 EVER Geologic Resource Evaluation Report 39 

the 1930’s, a series of canals and levees were constructed 

(including East Cape canal, Homestead canal, Slegel’s 

ditch, Houseman’s ditch, and Middle Cape canal) to 

divert the water away from the “prime” real estate 

around Cape Sable. The real estate venture failed and the 

land was later included in the park boundaries. The 

remediation of the canals and earth works is a park 

responsibility.Canals throughout south Florida divert 

water away from the natural flow between Lake 

Okeechobee and the Everglades. Locally, near Cape 

Sable and Lake Ingraham, the flow is disrupted and 

sediment transport patterns have changed. Fresh water 

marshes behind the cape are being salinated due to the 

overall lack of fresh water input. 

Sediment transport and resuspension at Cape Sable and 

Lake Ingraham 

The very nature of the landscape at the Everglades is one 

of change. Shifting muds and sands continually alter the 

shape and profile of the shoreline. Sand and mud erode 

from one beach and are deposited elsewhere in the 

course of a single storm event. A focus needs to be placed 

on understanding the sediment transport dynamics at the 

park. The hydrogeologic system in the area around Lake 

Ingraham was altered with the construction of canals, 

roads, and levees. As a result, sediments scouring 

through the canals are being deposited in the lake basin 

(6–30 cm/year, 2.4–11.8 in/year) and the lake levels are 

very low and bottom sediments are often exposed at low 

tide. The delta emanating from the Middle Cape Canal is 

expanding and increasing the sediment influx for the 

Florida Bay. Salinity is increasing as 80 high tides a year 

are cresting the low marl ridges. Higher salinity waters 

are encroaching on the fresh water areas. This leads to a 

decline in marsh, mangrove, and prairie areas. 

Research and monitoring questions and suggestions: 

• Are declines in mangrove, marsh, and prairie areas due 

to the canal system or due to sea level rise around Lake 

Ingraham or both? 

• USGS survey points are too far apart for proper 

monitoring of landscape response to sea level rise 

(~400 m [1,312 ft] apart). Can the number of these 

points be increased? 

• Should fill dams be destroyed or reestablished? 

• What remediation can be done on the eroded canal 

openings (erosion rate is 0.6–1.2 m/year [2–4 ft/year])? 

• What is the rate of change in sediment transport 

around Cape Sable? 

• How much sediment is being lost through canal 

scouring? 

• What would be the effects of replugging the Middle 

Cape Canal? 

Sinkholes and karst features 

The Fort Thompson limestone is a very permeable unit. 

Borrow pits and canals intersect this unit in many 

locations of the park. This is affecting water flow. 

Approximately 50 sinkholes have been located in the 

park. These serve as vital habitat during the dry season. 

However, their distribution, characteristics, depths, and 

interconnectedness need to be systematically mapped 

and described. 

Research and monitoring questions and suggestions: 

• What steps should be taken to model water flow in the 

park regarding karst features? 

• Could aerial photography be used to map sinkholes? 

• What is the relationship, if any, between solution holes 

and other karst features and the distribution of 

hardwood hammacks and tree islands at the park? 

Paleoclimates 

Cores in Florida and Biscayne Bays, and numerous 

sloughs in the park show peat and pollen as indicators of 

past climates. The spatial coverage for the cores is not at 

an adequate resolution to determine the temporal 

relationships and to make accurate interpolations 

between points. Bioturbation and other ground 

disturbances (railroad infill effects) distort the 

subsurface features. 

Research and monitoring questions and suggestions 

include: 

• Perform more coring operations to increase coverage 

at the park. 

• Identify pollen species and correlate with 

paleoclimate. 

Sea level rise 

Sea level rise is affecting all of South Florida. While 

slowing the rate of sea level rise is beyond the resources 

of the park, monitoring sea level change and evaluating 

and predicting impacts on the park’s landscape is a valid 

management issue. The fresh water marshes and 

brackish estuaries are under constant threat of 

inundation by the sea. Given the low relief of the park, 

this rise will destroy much of the marsh landscape 

protected at the park. Sea level rise is also causing beach 

erosion near Cape Sable and Lake Ingraham. Increases in 

turbidity with rising seas are causing large seagrass 

dieoffs and increased carbonate material suspension. 

Research and monitoring questions and suggestions 

include: 

• Is there any way to save the subaerial habitat from 

rising seas? 

• What is the local rate of sea level rise? 

• Looking at the affects of storm surges, how will the 

buttonwood and mangrove zones respond to the rising 

water? 

• What direction should future planning proceed in light 

of the current restoration effort? 

• Monitor and measure the relationship between water 

level flux and elevations to determine an 

exposure/submergence index (i.e. 100% of the time 

exposed versus 0% of the time exposed). 

• Quantitatively define the terms subtidal, intertidal, and 

supratidal to use for future predictions and relate these 
40 NPS Geologic Resources Division 

to the local elevations and annual regime of water 

fluctuations. 

Geologic changes due to storms and hurricanes 

Storm events and hurricanes have a pronounced and 

often catastrophic effect on the landscape of south 

Florida. Baseline conditions must be determined and 

studied for the resource management to predict the 

environmental response. Hurricane Donna in 1960 

evacuated water from the bay by about 1 m (3 ft), then 

the water rushed back in to a depth of 2.1 m (7 ft). This 

resulted in mud deposition on the south side of the mud 

ridges and a high-energy shell layer deposit on the north 

side. Hurricane Andrew blew the highland beach area 

near the Ross River away. Geochemical changes resulting 

from the influx of storm water went unmeasured during 

cleanup and restoration operations by local agencies. 

Research and monitoring questions and suggestions 

include: 

• Develop a response protocol in cooperation with 

other local agencies to determine the geochemical 

effects of storm surges. 

• What are the recovery rates of mangroves after large 

storm events? 

• Establish baselines for comparison and prediction of 

future events. 

Atmospheric deposition of African dust 

Dust has been blowing across the Atlantic Ocean and 

depositing in south Florida for thousands of years. 

Paleosols and reddish (oxidized) layers atop the Miami 

Limestone attest to these airborne inputs. The process 

continues today, but modern development has 

introduced nutrients, elements, microbes, pesticides, 

soot, organics, bacteria, viruses, and other contaminants 

to the dust. The dust diminishes air and water visibility. A 

peak of dust fall in the 1980s coincided with a sea urchin 

disease and other benthic die-offs. Lead, arsenic, 

phosphate, copper, iron, and mercury concentrations in 

the surface sediments in the middle of Florida Bay are 

highest in low tidal flux areas. 

Research and monitoring questions and suggestions 

include: 

• There are 9.1 m (30 ft) monitoring wells in the bay; 

these could be expanded and utilized (contact Gene 

Shinn). 

• Did the combination of dust and hypersalinity kill sea 

grass and cause algal blooms in Florida Bay? 

• Monitor dust levels and attempt to correlate with 

environmental responses. Are dieoffs caused by 

African dust or by the transport of sediments, 

nutrients, and organics transported out during rising 

seas and storms? 

“Lake Belt” management 

The term “Lake Belt” refers to a series of quarries near 

the park. These features are supposed to supply water to 

the park as part of a restoration effort. There is some 

concern about how these features are affecting 

groundwater movement. Some USGS monitoring wells 

are located near levees, but more wells would increase 

the understanding of the local hydrogeologic system. 

Local agriculture introduces sulphates, phosphorus, and 

other contaminants into the groundwater near these 

lakes that, given the permeable, conduit-rich bedrock, 

would easily contaminate the water in the quarries and 

affect the ecosystem of the park. 

Tree islands and hardwood hammocks 

Tree islands and hardwood hammocks are prevalent 

features at the Everglades. They dot the sawgrass prairies 

throughout the park. They appear to be oriented in linear 

trends. There is discussion as to whether the islands and 

hammocks are located in bedrock highs or lows. They 

could be located in peat depressions, or perhaps on a 

laminated duracrust formed by phosphorus from 

evaporites pulled up by the trees in the groundwater. 

Rock ridges, such as that at Rock Reef Pass, are subtle, 

enigmatic linear features on the landscape at the 

Everglades. There are approximately 20 rock ridges in 

south Florida. The amount of relief associated with these 

ridges is small, approximately 0.9–1.5 m (3–5 ft), but the 

vegetation changes across them and makes them appear 

more pronounced. Many theories abound as to why 

these features exist. Are they paleoshores, results of 

Pleistocene wrench faulting, developed fractures, 

concentrations of shells in oolite, paleo mudbanks, or the 

result of differential compaction and fracturing? 

Research and monitoring questions and suggestions 

include: 

• Can hydrogeochemistry determine if the bedrock is a 

source of phosphorous for these trees? 

• How did the tree islands and hardwood hammocks 

form? 

• What is the geologic control on their distribution? 

• Are their linear trends related to elongated paleoflows? 

• Obtain more cores in a transect through a rock ridge to 

help determine why they exist. 

• Core tree islands to bedrock to determine the nature 

of their formation. 

• Install a monitoring well into the tree islands to look at 

differences in local groundwater chemistry. 

Archaeological sites 

There are several sites, approximately 12,000 years old, 

along ancient coastlines that contain artifacts from the 

local indigenous populations. Mapping and/or 

reconstructing these sites would add to the cultural value 

of the park and help reconstruct the paleoshoreline in 

the 10,000 lakes, and Cape Sable areas especially. 
 EVER Geologic Resource Evaluation Report 41 

Scoping meeting participants 

NAME AFFILIATION PHONE EMAIL 

Andrea Atkinson NPS, SFCN 305-224-4245 andrea_atkinson@nps.gov 

Sonny Bass NPS, EVER 305-242-7833 sonny_bass@nps.gov 

Sid Covington NPS, Geologic Resources 

Division (303) 969-2154 sid_covington@nps.gov 

Kevin Cunningham USGS 

Robert Ginsburg University of Miami, RSMAS 305-421-4875 rginsburg@rsmas.miami.edu 

Melanie Harris USGS, CCWS 727-803-8747 

x3023 mharris@usgs.gov 

Fred Herling NPS, EVER/DRTO 305-242-7704 fred_herling@nps.gov 

Todd Hickey USGS 727-803-8747 

x3040 tdhickey@usgs.gov 

Kelly Jackson University of Miami, RSMAS 305-421-4811 x4 kjackson@rsmas.miami.edu 

Bob Johnson NPS, EVER/DRTO 305-224-4240 robert_johnson@nps.gov 

Harley Means Florida Geological Survey 850-488-9380 guy.means@dep.state.fl.us 

Sherry MitchellBruker NPS, EVER 305-224-4286 sherry_mitchell@nps.gov 

Doug Morrison NPS, EVER/DRTO 305-852-0324 

x0327 douglas_morrison@nps.gov 

Lisa Norby NPS, Geologic Resources 

Division 303-969-2318 lisa_norby@nps.gov 

Matt Patterson NPS, SFCN 305-224-4211 matt_patterson@nps.gov 

Anne Poole NPS, Geologic Resources 

Division 303-987-6954 anne_poole@nps.gov 

Tom Schmidt NPS, EVER 305-224-4269 tom_schmidt@nps.gov 

Eugene Shinn USGS 727-803-8747 

x3030 eshinn@usgs.gov 

Dewitt Smith NPS, EVER 305-242-7818 dewitt_smith@nps.gov 

Trista ThornberryEhrlich Colorado State University 757-222-7639 tthorn@cnr.colostate.edu 

Brigitte Vlaswinkel University of Miami, RSMAS 305-421-4918 bvlaswinkel@rsmas.miami.edu 

Harold Wanless University of Miami, 

Geological Sci. 305-284-4253 hwanless@miami.edu 

Britton Wilson NPS, SFCN britton_wilson@nps.gov 

Linda York NPS, SERO 404-562-3133 

x537 linda_york@nps.gov 

The Department of the Interior protects and manages the nation’s natural resources and cultural heritage; provides scientific and other 

information about those resources; and honors its special responsibilities to American Indians, Alaska Natives, and affiliated Island 

Communities. 

Everglades National Park 

Geologic Resource Evaluation Report 

Natural Resource Report NPS/NRPC/GRD/NRR—2008/047 

NPS D-345, September 2008 

National Park Service 

Director • Mary A. Bomar 

Natural Resource Stewardship and Science 

Associate Director • Bert Frost 

Natural Resource Program Center 

The Natural Resource Program Center (NRPC) is the core of the NPS Natural Resource Stewardship and 

Science Directorate. The Center Director is located in Fort Collins, with staff located principally in 

Lakewood and Fort Collins, Colorado and in Washington, D.C. The NRPC has five divisions: Air 

Resources Division, Biological Resource Management Division, Environmental Quality Division, Geologic 

Resources Division, and Water Resources Division. NRPC also includes three offices: The Office of 

Education and Outreach, the Office of Inventory, Monitoring and Evaluation, and the Office of Natural 

Resource Information Systems. In addition, Natural Resource Web Management and Partnership 

Coordination are cross-cutting disciplines under the Center Director. The multidisciplinary staff of NRPC 

is dedicated to resolving park resource management challenges originating in and outside units of the 

national park system. 

Geologic Resources Division 

Chief • Dave Steensen 

Planning Evaluation and Permits Branch Chief • Carol McCoy 

Credits 

Author • Trista Thornberry-Ehrlich

Review • Linda York and Carol McCoy 

Editing • Melanie Ransmeier

Digital Map Production • Stephanie O'Meara and Trista Thornberry-Ehrlich 

Map Layout Design • Melanie Ransmeier
Geologic Resources Division 

Natural Resource Program Center 

P.O. Box 25287 

Denver, CO 80225 

http://www.nature.nps.gov/geology/inventory/ 

(303) 969-2090 

EXPERIENCE YOUR AMERICATM 

National Park Service 

U.S. Department of the Interior