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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 Turtle Shoal: East Turtle Shoal is one of the mid-channel patch-reef clusters that formed on the landward edge of the bedrock trough seaward of the middle and lower Keys (Lidz et al., 2006). East Turtle Shoal (Fig. 56B) is mentioned because it is the nearest named locale to treasure-salvor 'footprints' that are clearly visible in aerial photos of the seagrass bed east of the shoal (see Benthic Ecosystems for Tile 4). The footprints are circular to teardrop-shaped patches of bare sand in surrounding sea grasses. They result from use of special mechanical devices called mailboxes. Attached at the back of a boat, mailboxes direct the prop wash downward to blow or excavate sand from an area to locate artifacts. The holes created are usually about 10 m in diameter and 6 m deep. The largest sand hole at this site is estimated from on-screen measurement of the enlarged aerial photo to be about 60 by 120 m in size. The depth of the hole is unknown. The salvors' transect covers a distance of approximately 1.5 km. The Florida Keys and The Quicksands in the Gulf of Mexico (Fig. 6A) are well known for the many gold- and silver-laden Spanish galleons that were claimed by shoal waters during hurricanes. continue to: Coffins Patch

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