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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 4 Geography Sector-Specific Studies Geologic Highlights East Sister Rock Moser Channel East Washerwoman Shoal and Other Patch Reefs in Hawk Channel East Turtle Shoal Coffins Patch Delta Shoal and Sombrero Key Reef East Sister Rock: Coring has shown that, except for coral spurs (e.g., Shinn, 1963, 1980a; Lidz et al., 1985), modern reefs of the Florida Keys developed on sediment-free bedrock highs (e.g., Shinn et al., 1977a, 1989a). It has long been known from field observations, however, that Holocene corals did not colonize all bedrock highs. No one knows why. One such uncolonized area has been documented seismically (Lidz et al., 2003). East Sister Rock lies just off the east-southeast corner of Vaca Key (Figs. 68B, 69) in ~5 m of water. The surface of East Sister Rock is about 6 m below sea level and is covered by thin Holocene sediments (Fig. 73). Surrounding bedrock is slightly deeper (~7 to 8 m below sea level). Figure 73. Seismic profile northeast of East Sister Rock (south of Vaca Key in the middle Keys, Fig. 68B) shows bedrock high not colonized by Holocene reefs but surrounded and covered by Holocene sediment (from Lidz et al., 2003). 'Multiples' are an artifact common in seismic-reflection data. These reflections replicate those of existing, overlying, geologic surfaces and should not be regarded as representing any subsurface stratigraphic horizon. Latitude and longitude in degrees and decimal minutes based on GPS coordinates. Hours (military time) below coordinates serve as navigational correlation points along seismic line. [larger version] continue to: Moser Channel

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