Interactive Reference

The Rock Map

An interactive taxonomy of every rock type found in Florida — from surface limestone and coquina to the ancient igneous and metamorphic basement thousands of feet below.

Click any category to explore its rock types. Click a type to reveal specific formations with descriptions and links to authoritative sources. Florida's accessible geology is almost entirely sedimentary, but deep well cores reveal igneous and metamorphic basement rocks of African origin.

Florida Rock Types

Ocala Limestone Late Eocene (~40–34 Ma). Thick, pure limestone. Primary component of the upper Floridan Aquifer — Florida's most important groundwater source. Florida Geological Survey Miami Limestone Late Pleistocene (~130–120 Ka). Oolitic and bryozoan limestone underlying southeast Florida. Foundation of the Miami metropolitan area. U.S. Geological Survey Key Largo Limestone Pleistocene fossil coral reef. Forms the geological foundation of the Upper Florida Keys. Preserved ancient reef tract. NPS — Biscayne National Park Suwannee Limestone Oligocene (~34–23 Ma). Underlies north-central Florida. Contains karst features and early Floridan Aquifer zones. Florida Geological Survey Tampa Limestone Late Oligocene to Early Miocene. Found in west-central Florida. Often contains chert inclusions and abundant marine fossils. Florida Geological Survey

Avon Park Formation Middle Eocene. Alternating dolomite and limestone layers. Important aquifer unit in central Florida underlying the Ocala Limestone. Florida Geological Survey Cedar Keys Formation Paleocene. Deep dolomite and anhydrite unit. One of the oldest sedimentary formations in the Florida sequence, encountered in deep well cores. U.S. Geological Survey

Anastasia Formation Pleistocene (~126–10 Ka). Coquina limestone underlying the Atlantic coast from St. Augustine to Palm Beach. Built the Castillo de San Marcos. NPS — Castillo de San Marcos Modern Beach Rock Holocene. Recently cemented coastal deposits forming today along Florida's shoreline. Incipient coquina in the making. Florida Geological Survey

Hawthorne Group Sands Miocene (~23–5 Ma). Phosphatic sands and clays. Acts as confining layer over the Floridan Aquifer. Source of Florida's phosphate wealth. Florida Geological Survey Cypresshead Formation Pliocene–Pleistocene. Unfossiliferous red and orange sands forming the high ridge areas (Trail Ridge, Lake Wales Ridge) of central Florida. U.S. Geological Survey

Bone Valley Formation Late Miocene to Early Pliocene. World-class phosphate deposit in central Florida. Also one of the richest vertebrate fossil sites in North America. USGS National Minerals Information Center Hawthorne Phosphatic Units Miocene. Phosphatic sands, clays, and carbonates distributed across much of peninsular Florida. Secondary phosphate source. Florida Geological Survey

Tampa Member Chert Silica replacement nodules found within the Tampa Limestone. Used by Florida's earliest inhabitants as tool material. Florida Museum of Natural History Silicified Coral Chalcedony and opal replacement of fossil corals. Found throughout Florida formations where silica-rich groundwater permeated carbonate rock. Florida Geological Survey

Fort Thompson Formation Pleistocene. Freshwater marl and limestone in south Florida. Key substrate underlying parts of the Everglades ecosystem. U.S. Geological Survey Everglades Peat Holocene. Organic deposits up to 12 feet thick forming the living substrate of the Everglades. Actively accumulating today. NPS — Everglades National Park

Osceola Granite Precambrian. Encountered in deep well cores in central Florida. Isotopic dating confirms African continental origin. U.S. Geological Survey Basement Granodiorite Paleozoic. Intermediate composition plutonic rock found in deep south Florida well cores. Florida Geological Survey

Paleozoic Volcanics Ordovician to Devonian volcanic rocks encountered in deep well cores across the peninsula. Part of the Gondwanan volcanic arc. Florida Geological Survey Triassic Rift Basalt Mafic volcanic rock from the Triassic–Jurassic rifting event that opened the Atlantic Ocean (~200 Ma). U.S. Geological Survey

Mesozoic Dike Intrusions Jurassic–Cretaceous mafic dikes related to the opening of the Atlantic Ocean and Gulf of Mexico basin. U.S. Geological Survey

Pan-African Gneiss Precambrian (~1 Ga+). High-grade metamorphic rock matching West African basement geology. Key evidence for Florida's Gondwanan origin. U.S. Geological Survey

Basement Quartzite Paleozoic. Metamorphosed sandstone from the ancient Gondwanan continental margin. Encountered in deep well cores. Florida Geological Survey

Mica Schist Precambrian–Paleozoic. Micaceous foliated metamorphic rock from deep south Florida basement cores. U.S. Geological Survey

Basement Amphibolite Precambrian. Dark hornblende-rich metamorphic rock found in scattered deep well cores across the Florida Platform. U.S. Geological Survey

Sedimentary — surface & near-surface

Igneous — deep basement only

Metamorphic — deep basement only

Context

Understanding Florida's Rock Record

Florida's geology is unique among U.S. states. While the surface is composed almost entirely of sedimentary rocks — limestones, dolostones, sandstones, and unconsolidated deposits laid down in shallow marine environments over hundreds of millions of years — deep well cores reveal a hidden basement of igneous and metamorphic rocks that originated on the African continent before the breakup of Pangaea.

The sedimentary sequence is extraordinarily thick, reaching 10,000 to 15,000 feet in places. This massive accumulation of carbonate rock is the reason Florida has karst topography (sinkholes), abundant springs, and one of the world's most productive aquifer systems. The rock formations visible at the surface — from the Eocene Ocala Limestone to the Pleistocene Anastasia Formation — represent only the most recent chapters in a geological story spanning half a billion years.

Explore the complete narrative in our Florida Geological Timeline, or dive into specific topics through our articles on coquina, fossil hunting, and coastal geology.