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Systematic Mapping of Bedrock and Habitats along the Florida Reef Tract—Central Key Largo to Halfmoon Shoal (Gulf of Mexico)

USGS Professional Paper 1751

by Barbara H. Lidz, Christopher D. Reich, and Eugene A. Shinn

Introduction: Table of Contents Project Overview Project Objective Geologic Setting Primary Datasets Primary Products - Overview Maps & Evolution Overview: Introduction Depth to Pleistocene Bedrock Surface Reef & Sediment Thickness Benthic Ecosystems & Environments Sedimentary Grains in 1989 Summary Illustration Index Map Evolution Overview Tile-by-Tile Analysis Organization of Report Tiles: 1, 2, 3, 4, 5, 6, 7/8, 9/10, 11 Summary Acknowledg- ments References Disclaimer Related Publications

Tile 2 Geography Sector-Specific Studies Geologic Highlights Nearshore Rock Ledge Plantation, Windley, and Lignumvitae Keys Tavernier Key Conch Reef Davis and Alligator Reefs Plantation, Windley, and Lignumvitae Keys: Plantation and Windley Keys (Figs. 42B, 46B) have some of the highest elevations (~5.5 m above sea level) in the inhabited islands of the Florida Keys (Lidz and Shinn, 1991). Elevation of Lignumvitae Key is comparable, though the island is uninhabited. Lignumvitae Key has enough soil to support a dense hardwood forest that is fringed on its south side by mangroves (see Benthic Ecosystems for Tile 2). Windley Key is the site of an old limestone quarry. Though closed as an active quarry many years ago, quarrying activities left a valuable dry-land view inside the coral reef that built the middle and upper Keys about 125 ka (e.g., Hoffmeister et al., 1967). The coral reef is known as the Key Largo Limestone (Sanford, 1909). Entire coral skeletons are visible in the quarry walls (Fig. 46A, 47B). The reef varies in composition but typically contains massive reef-framework-building head corals Montastrea annularis, M. cavernosa, Porites astreoides, Siderastrea siderea, Solenastrea bournoni, Colpophyllia natans, and Diploria strigosa (e.g., Hoffmeister et al., 1967; Hoffmeister and Multer, 1968; Hoffmeister, 1974; Perkins, 1977). Montastrea annularis is by far the dominant coral in this reef and elsewhere in the Pleistocene coral record of Florida. (See Regional Geologic Setting for an explanation of the Pleistocene.) Figure 47. (A) Photo of coral skeletons in wall of Windley Key Quarry. Vertical holes are drill bore sites for cutting and excavating limestone blocks. (B) Photo shows skeletal Diploria species in Windley Key Quarry wall. [larger version] Because of its historic and scientific significance, the quarry was designated the Windley Key Fossil Reef Quarry State Geological Site in January 1999. The site now includes a museum that houses a pictorial history of the quarry and hands-on displays that explain the story of the ancient coral reef. continue to: Tavernier Key

Coastal & Marine Geology Program > Center for Coastal & Watershed Studies > Professional Paper 1751