Heidi Krantz, age 9, of  Hattesburg, Miss., for her question:

HOW LARGE AN AREA DOES THE EVERGLADES COVER?

The Everglades are one of the largest and most interesting swamp areas in the world. Located in the southern part of Florida, the Everglades cover 2,746 square miles as they stretch from Lake Okeechobee in a sweep about 40 miles wide and 100 miles long, merging into salt water marshes and mangrove swamps near the Bay of Florida and the Gulf of Mexico.

The northern and eastern parts of the Everglades are plains covered by sawgrass that grows as high as 12 feet in some places. Wax myrtles, willows, bays and custard apples grow in clumps of higher lands called tree islands.

The soils in the Everglades are made up largely of muck and peat, which are the remains of decayed plant life, and of gray marl.

The low basin which makes up much of the Everglades region was once the bottom of a sea. During the Ice Age, the region was alternately flooded with seawater and drained, as the ice sheets advanced and retreated. When the last ice sheet retreated, the sea rose and flooded the outlets of Everglades streams.

In 1947, the southwestern part of the region became the Everglades National Park.