Biscayne National Park: Keys Built of Pleistocene Limestone

Just south of Miami, Biscayne National Park protects subtropical islands, called keys, along with coastline and coral reefs, at the northern end of the Florida Keys and southern Biscayne Bay in Miami-Dade County, Florida.

The Stiltsville area of Biscayne National Park. Image from the National Park Service's page.

The park

First authorized as a national monument on October 18, 1968, it was redesignated and enlarged as a national park on June 28, 1980. It covers about 69,998 hectares (172,971 acres) and protects:

• the longest stretch of mangrove forest on Florida's east coast;
• part of the world's third-longest barrier reef ecosystem;
• the clear, shallow waters of Biscayne Bay and the Atlantic Ocean.

The park's reefs are the northern end of the Florida Reef, a coral barrier reef tract some 275 km (170 mi) long that also takes in Dry Tortugas National Park. Its mangrove coasts, fragile coral reefs, estuarine bays and marine nursery habitats are an integral part of the South Florida ecosystem and sustain rich native fisheries. Its cultural history goes back thousands of years: early Native American occupation, Spanish and English exploration, pirates, shipwrecks, maritime smuggling, agriculture and modern commercial development.

The rocks

The park lies in the Florida Keys and Southern Atlantic Coastal Strip subsections of the Atlantic Coastal Plain, a low-lying, geologically young region of subtropical coast and keys resting on loose Cenozoic sediments.

Both limestones were named by Sanford in 1909.

Coral reef at Biscayne National Park. Image from the National Park Service's page.

The park belongs to the Coastal Plain physiographic province and shares its geologic history, and some of its characteristic formations, with a region reaching far beyond the park.

Maps and inventories

The Park Service's Geologic Resources Inventory, which produces digital geologic maps and reports for more than 270 natural resource parks, has products for Biscayne, and a Soil Resources Inventory has been completed for the park. Both are on the NPS DataStore.

Sources

Based on "NPS Geodiversity Atlas—Biscayne National Park, Florida," National Park Service Geologic Resources Inventory, which cites National Park Service (2016, 2018) and Sanford (1909); a work of the United States government in the public domain.