How Big are the Everglades in Florida?

Part prairie, part jungle, and part flowing water, Florida’s “river of grass” is an unmatched paradise. Much of the lower part of the Florida peninsula, from Lake Okeechobee south to Florida Bay, forms the bed of one of the most unusual rivers in the world. Extremely broad, shallow, and covered by a film of water flowing almost imperceptibly toward the sea, the “river” covers some 4,000 square miles (10,500 square kilometers)—an area about twice the size of Delaware. Although the region is dotted with small wooded islands and fringed by mangrove swamps along the coast, most of it is a vast waterlogged prairie laced with a maze of ponds and open channels. Native Americans called it Pa-hay-okee, the “grassy river”; modern man calls it the Everglades.

The region, like the rest of the Florida peninsula, is underlain by a foundation of ancient volcanic and metamorphic rock. Submerged time and again beneath the sea over the course of tens of millions of years, the basement rock was covered by layer upon layer of sediments (mostly the remains of marine animals) that were compacted into limestone.

The most recent changes in sea level resulted from the repeated advances and retreats of continental glaciers during the Ice Age. When the glaciers advanced, large amounts of water were locked up in the form of ice, and sea levels all around the world were lowered. When the glaciers retreated, melt water raised sea levels.

With the last retreat of the glaciers, the Florida peninsula assumed more or less its present contours about 6,000 years ago. The southern part of the state now resembles a broad, shallow limestone trough, bounded by a low ridge along the Atlantic Coast and a slight rise in elevation along the Gulf Coast. The entire intervening depression, moreover, is tilted slightly toward the south.

This trough forms the bed of the Everglades, sometimes known as the “river of grass.” The water supply that feeds it is the 60 inches (1,500 millimeters) or more of rain that falls each year on Florida. Runoff water from as far away as the central part of the state, well to the north of Lake Okeechobee, is funneled southward across the Everglades as it flows slowly toward the sea.

Because of the Everglades’ wetness and flatness (the highest “hills” measure only about 10 feet, or 3 meters), slight differences in elevation result in profound changes in scenery. Low coastal areas where fresh water mingles with the sea are covered by dense, tangled forests of mangroves. Inland, shallow freshwater ponds often support stands of immense bald cypress trees, which, like the mangroves, are adapted for growing with their rootspermanently submerged under water, islands of higher ground, in contrast, support entirely different sorts of trees. Some are‘ covered by pine groves. Others, known locally as bay-heads, rise ,as low mounds of bays, hollies, and other types of trees found throughout the southeastern states. Most impressive of all are the so-called hammocks—jungle like forests that include many tropical species of trees, their branches tufted with dense growths of orchids, ferns, bromeliads, and other exotic air plants.

But most of the Everglades is overgrown with prairies of sawgrass, a type of sedge named for the serrated edges of its tall grasslike leaves. Covered by a film of water for at least part of the yea4 these flat, seemingly endless expanses of rippling sawgrass are interrupted only by sloughs (natural drainage channels of open water), ponds (some of them created by alligators wallowing in the mucky soil), and here and there low islands of trees.

The most remarkable feature of the Everglades, however, is the spectacular concentrations of wildlife that flourishes there—particularly in the southernmost sector, which has been set aside as Everglades National Park. The most conspicuous residents there are birds—some 300 species in all—including spoonbills, herons, egrets, pelicans, anhingas, ibises, and scores more. Other creatures range from otters to alligators, turtles, and tree frogs. Like the vegetation, all depend on the steady flow of life-giving water that streams slowly southward across Florida’s unique river of grass.  Sarah writes the Czech Travel Guide and is looking forward to visiting the US soon.