Introduction

Recent USGS mapping shows an extensive deep (~100 m) reef tract occurs on the Mississippi-Alabama outer continental shelf (Figure 1). The tract, known as "The Pinnacles", is apparently part of a sequence of drowned reef complexes along the "40-fathom" shelf edge of the northern Gulf of Mexico (Ludwick and Walton, 1957). It is critical to determine the accurate geomorphology of these deep-reefs because of their importance as benthic habitats for fisheries. The Pinnacles have previously been mapped using a single-beam echo sounder (Ludwick and Walton,1957), sidescan sonar (Laswell et al., 1990), and the TAMU² towed single-beam sidescan-sonar system (Anonymous, 1999). These existing studies do not provide the quality of geomorphic data necessary for reasonable habitat studies.

Geodetically accurate bathymetry maps, coregistered with calibrated acoustic backscatter maps, are critical to delineate benthic biotopes, and are essential to correlate biological community differentiation with the physical environment. In May-June and July of 2000, the U.S Geological Survey mapped the Pinnacles Region using a state-of-the-art multibeam sonar system (Figure 1). This Open File Report publishes the bathymetry and acoustic backscatter data along with FGDC-compliant metadata, images, and a GIS of this survey.

For more information, see the Pinnacles Area Multibeam Cruise Report, or visit the Pacific Seafloor Mapping website.

TOP OF PAGE

References

Anonymous.1999. Northeastern Gulf of Mexico coastal and marine ecosystem program: Ecosystem monitoring, Mississippi/Alabama shelf, 3ed annual interim report. Minerals Management Service. 210p.

Laswell, J.S., Sager, W. W., Schroeder, W. W., Rezak, R., Davis, K.S., and Garrison, E. G., 1990. Mississippi-Alabama Marine Ecosystem study: Atlas of high-resolution geophysical data. Mineral Management Service, OCS Study MMS 90-0045. 40p.

Ludwig, J.C and Walton, W.R., 1957, Shelf-edge calcareous brominences in northeastern Gulf of Mexico. Bull. Amer. Assoc. Petroleum Geologists, v. 41, p. 2054-2101.

The multibeam bathymetry and acoustic backscatter data are available in two formats; ASCII XYZ and ArcInfo GRID. FGDC metadata is provided for each format and and is available in three different forms, FAQ (Frequently Anticipated Questions), HTML, and text.

ASCII XYZ
FAQ
HTML
TEXT

ArcInfo GRID
FAQ
HTML
TEXT