Lake Okeechobee Valley and the Everglades. The trough is underlain by clay deposits that compacted more than the limestone and sand deposits did along both coasts of peninsular Florida. Until about 6,000 years ago, the trough was dry land. As the sea level rose, the water table in Florida also rose and rainfall increased. From 6,000 to 4,000 years ago, wetlands formed building up peat deposits. Eventually the water flow into the area created a lake, drowning the wetlands. Along what is now the southern edge of the lake, the wetlands built up the layers of peat rapidly enough (reaching thick) to
Miami River (Florida) to improve the river's condition. Although it is widely believed that the name is derived from a Native American word that means "sweet water", the earliest mention of the name comes from Hernando de Escalante Fontaneda, a captive of Indians in southern Florida for 17 years, when he referred to what is now Lake Okeechobee as the "Lake of Mayaimi, which is called Mayaimi because it is very large". The Mayaimi Indians were named after the lake, beside which they lived. Spanish records include the cacique of "Maimi" in a group of 280 Florida Indians that arrived in Cuba in