The Miami Rock Ridge is an oolitic, continuous outcrop of limestone, part of the Miami Formation, which formerly encompassed a large extent of southernmost South Florida; as part of an ecosystem it formed portions of the Everglades. The traditional base of the elevation, which rises 7 to 8.6 m above sea level, ranges from northern Miami-Dade County—the approximate latitude of North Miami Beach—southward to the upper Florida Keys and extends southwestward into Everglades National Park, creating a karst-dominated landscape. A series of tidal channels, dubbed transverse glades, formed within valleys in the ridge and served as conduits for freshwater from the Everglades, thereby modulating the estuarine environment of Biscayne Bay. One of these glades enclosed the Miami River, a section of whose course featured a 6 ft waterfall and 450 ft rapids until 1908, when it was progressively bypassed by the Miami Canal and partly dredged. Being one of the few areas sited above pre-drainage sea level, the Miami Rock Ridge was heavily exploited for agriculture and real estate.

Description

The coastal ridge was traditionally a component of the endangered pine rocklands, which grew upon the length of the ridge. The environmental community consisted of a large and continuous expanse of South Florida slash pines (Pinus elliottii var. densa), which was interspersed by tropical hardwood hammocks. The globally imperiled pine rockland community, which also encompassed the Florida Keys and The Bahamas, supported numerous endemic plant species; 20 percent occur nowhere else in the world. The communities of the Miami Rock Ridge are maintained by wildfires, including natural fires caused by lightning strikes; this affects the vegetation and its associated inhabitants, thus maintaining a diverse ecosystem. The substrate—often consisting of marl—and climate also affects the height of vegetation; thus a mature subtropical hammock typically does not exceed 59 ft on the Miami Rock Ridge. Today the original communities have been largely removed by development, and the remaining pieces of the ecosystems are scattered into tiny fragments in extreme southeast Florida; they now encompass small fractions of their original range. Simpson Park Hammock and Alice Wainwright Park contain small fragments of tropical hardwood hammock.

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