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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 5 Geography Sector-Specific Studies Geologic Highlights Tile 5 Coordinates: 24°39'19.51" N. 81°25'53.42" W. 24°43'20.71" N. 81°10'11.27" W. 24°36'19.52" N. 81°07'59.14" W. 24°32'15.45" N. 81°23'47.41" W. Major Geographic Sites: Tile 5 includes Moser Channel, Bahia Honda Key, Bahia Honda Channel, and Newfound Harbor Keys (middle Keys), and the southernmost parts of Ramrod, Torch, and Big Pine Keys (lower Keys) (Fig. 77A, 77B, 77C). Newfound Harbor Keys are the westernmost of the middle Keys. Offshore features include Big Pine Shoal and prominent coral-rock ridges, specifically those just inshore of Marker G. The FKNMS has designated an area just south of the westernmost island of the Newfound Harbor Keys as a Research Only Area (see Marine Sanctuaries). The area is one of patch reefs on the outer part of the nearshore rock ledge. Figure 77. (A) Landsat satellite image of south Florida shows individual tile boundaries (blue rectangles) of this regional study in the Florida Keys National Marine Sanctuary. Tile 5 is highlighted. (B) Index map shows locations of named reefs and shoals in the upper Keys and northeastern middle Keys, delineated by dashed lines. Most named reefs and shoals were once historic islands. Red rectangles show geographic boundaries of Tiles 1, 2, 3, and 4. (C) Contiguous part of index map shows westernmost part of middle Keys and the lower Keys, delineated by dashed lines. Note the difference in island orientation. The upper and middle Keys are composed of the Pleistocene Key Largo Limestone coral reef. The lower Keys consist of oolitic tidal bars of the same age known as the Miami Limestone. Both rock formations accumulated during a stand of sea level at ~125 ka that was higher, perhaps by 10.7 m, than sea level is today. Red numbered rectangle denotes geographic boundaries of Tile 5 with its geographic sites highlighted. Sanctuary boundary is in red; shelf-margin contour is in blue. Contours are in meters. [larger version] continue to: Sector-Specific Studies

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