Geology of Everglades National Park

The Everglades National Park in southern Florida is how it is, as a direct result of the geologic events in its past. Although the landscape has been altered a little by the interference of humans (when will we ever learn to leave things alone?) the “bigger picture” of the park landscape is still visible.

The rocks which form the base of the Big Cypress Swamp are some of the oldest rocks in southern Florida. Cast your mind back six million years or so . . . too long ago to remember? Never mind, anyhow, around six million years ago the area was covered by shallow sea which deposited sediments of sand and silt particles, this was eventually compressed and became limestone – these days this rock is known as the Tamiami Foundation.  There’s also Tamiami Foundation towards the northwest of Everglades National Park where the fresh water flows from the Big Cypress and mixes in with the salt water in the mangrove estuary along the Gulf of Mexico. This place is prime habitat for pink shrimp, snapper and snoop – it’s a sort of nursery for marine life.

Other rocks found in the Everglades National Park were formed during the Great Ice Age. There weren’t any actual glaciers in Florida, but that doesn’t mean that the effects of the ice age weren’t felt. As the glaciers were expanding around the world it meant that the sea level dropped, up to around 300 feet in South Florida – lots of the water was simply trapped beneath the ice. When we say “The Great Ice Age” it’s because it was actually four “mini ice ages” running together, constantly freezing and then melting and returning water to the sea, at one point the sea level in South Florida actually rose around 100 feet higher than it is at present. This is when the rocks beneath the southeastern section of Everglades National Park were created.

The Everglades National Park is in southern Florida, and here, as in many more places, a subtle change in elevation can result in a dramatic change in the stuff which grows – the vegetation. Along the highest ground on this Atlantic Coastal Ridge are pine forests, whereas the wetter areas closer to end of the ridge are home to dwarf pond cypress. To the south of the ridge is prime country for sawgrass prairies and a narrow ribbon of mangroves meander along the southeast coast making these waters the perfect spot for sustaining large numbers of wading birds.