The Geology of Everglades National Park, Florida

Everglades National Park covers most of the southern tip of the Florida peninsula and most of Florida Bay, between the peninsula and the Florida Keys. It protects the largest remaining subtropical wilderness in the contiguous United States, on ground underlain by geologically young sedimentary rock. This summary draws on the National Park Service's Geodiversity Atlas, which gathers what the NPS Geologic Resources Inventory knows about each park's rocks, sediments, landforms, fossils, soils and the processes that shape them.

The park

The park lies in Miami-Dade, Monroe and Collier Counties. It was authorized on May 30, 1934, and established on December 6, 1947, and covers about 610,660 hectares (1,508,976 acres).

Its freshwater and saltwater environments include open sawgrass prairies, mangrove estuaries, tropical hardwood hammocks, pine rocklands and seagrass meadows. They support more than 400 species of birds and rare or threatened species including the Florida panther, West Indian manatee, American alligator, American crocodile, wood stork and Florida bristle fern. The park has been designated an International Biosphere Reserve (1976), a World Heritage Site (1979) and a Wetland of International Importance (1987).

Geologic setting

The park spans parts of three subprovinces of the Atlantic Coastal Plain — the Everglades, the Big Cypress Swamp, and the Mangrove and Coastal Glades. The Coastal Plain is a geologically young region underlain by Cenozoic sedimentary deposits. From oldest to youngest, the units at or near the surface are:

• Tamiami Formation (Pliocene). The oldest unit mapped at or near the surface: a fossil-rich mix of carbonate and siliciclastic rock, found in the northwestern part of the park.
• Miami Limestone (Pleistocene). Formerly called the Miami Oolite, it is a white to orangish-gray, fossil-bearing sandy limestone.
• Key Largo Limestone (Pleistocene). Named in 1909 from exposures on Key Largo, it is widespread along the Florida Keys. In the park's southeast it forms small islands and part of Key Largo, covered by younger carbonate mud and thin soils. Across the region it forms a band of carbonate rock 360 km (225 mi) long that reaches to North Miami Beach.
• Holocene surface deposits. The coastal areas are loose, recent sediments: marl, marl over peat, quartz sands, carbonate sands and mud, and organic material.

Geologic Resources Inventory map. National Park Service.

The park belongs to the Coastal Plain Physiographic Province and shares its geologic history and characteristic formations with a much larger region.

Protection and inventories

Fossils in national parks are protected under the Paleontological Resources Preservation Act of 2009, and caves under the Federal Cave Resources Protection Act of 1988. The Geologic Resources Inventory produces digital geologic maps, reports and posters for more than 270 natural resource parks, and a Soil Resources Inventory has been completed for Everglades. Both are available through the NPS DataStore.

Aerial view of Homestead Canal. National Park Service.

Sources

• National Park Service, "NPS Geodiversity Atlas—Everglades National Park, Florida": https://www.nps.gov/articles/nps-geodiversity-atlas-everglades-national-park-florida.htm
• The report cover shown on the source page is not reproduced.