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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 1 Geography Sector-Specific Studies Geologic Highlights Rodriguez Key Sinkhole Captain Roy's Reef Grecian Rocks Key Largo Dry Rocks Mosquito Bank, White Bank, Coral-Rock Ridges, and French Reef Carysfort Reef The Elbow Molasses Reef and Little Molasses Island Pickles Reef Key Largo Dry Rocks: Key Largo Dry Rocks is located southeast of Captain Roy's Reef and northeast of Grecian Rocks (see Benthic Ecosystems for Tile 1). The reef has prominent seaward-extending spurs and grooves and the same coral zonation as at Grecian Rocks. Although unrelated to geology of the keys, there is human-interest history behind the reef at Key Largo Dry Rocks. Key Largo Dry Rocks is famous for being the site of an underwater Christ statue that draws thousands of scuba divers each year. The statue, with arms uplifted to welcome divers, stands in a spur in 6.5 m (21 ft) of water. Known as "Christ of the Deep," the statue is a replica of another called "Christ Degli Abissi" or "Christ of the Abyss," which stands on the floor of San Fruttosa Bay in Italy. Both bronze statues were cast in 1962 from a single mold of the original sculpture created by Italian artist Guido Galletti. The 2.7-m-tall (9-ft) statue weighs 500 kg (1,102 lbs) and sits on six sunken concrete slabs weighing 3,175 kg (7,000 lbs) each. Mr. Egidio Cressi, the well-known skin-diving equipment manufacturer, presented the statue to the Underwater Society of America in 1962. After 12,870 km (8,000 mi) of travel, many months of storage in Chicago awaiting a decision and funding for its permanent home, and weeks of being on display in various cities en route to Key Largo, the statue was finally lowered into the water nearly 4 years after being cast. John Pennekamp dedicated the underwater statue in July 1966 in what at the time was called John Pennekamp Coral Reef State Park. Researchers should exercise caution when reading literature on Grecian Rocks and Key Largo Dry Rocks. Before 1970, three small reefs on the outer shelf off north Key Largo were collectively known as the Key Largo Dry Rocks. Sometime in the 1970s, the southwesternmost reef was named and appeared on official charts as Grecian Rocks (e.g., NOAA, 1984). Fishermen and early researchers previously called that reef Key Largo Dry Rocks. The middle reef is known locally as Little Key Largo Dry Rocks, though it is not named on charts. continue to: Mosquito Bank, White Bank, Coral-Rock Ridges, and French Reef

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