The Southern Florida Peninsula can be divided into two different regions:
1. The Atlantic Coastal Ridge; and,
2. The Everglades and Big Cypress Swamp
This area has a mean elevation of 3 meters which slopes down to sea level as one travels from Lake Okeechobee to the Gulf of Florida. This gives the land a slope of approximately 3.2 centimeter per kilometer.
The Atlantic Coastal Ridge which borders the eastern portion of the Everglades contains an area of mostly thin soils with a number of outcrops of exposed limestone bedrock. This ridge was formed by sea water flowing along a North-South submarine mound during an era when the ocean covered much of Southern Florida.
The calcium based soil of this region is composed of ooilites. These ooilites are composed of precipitated calcium from sea water and thus are inorganic. When the sea receded from Southern Florida, this ridge was exposed to rain water which percolated through the ooilites dissolving some of the calcium. The calcium, once precipitated from the rain water, cemented the ooilites together.
When Atlantic Coastal Ridge formed, it helped to protect the shallow inland sea that developed to its West. In this area bryozoans thrived and formed calcareous colonies. When the sea water recede these bryozoans died and formed a calcium based organic limestone. This limestone eventually formed a calcitic soil in which species of the marl prairies now thrive. Hydroperiod along with vegetation then set in place the microtopographic variation in which marl prairies and sawgrass stands would grow and exist.
Source Land from the Sea by John Hoffmeister © 1974