Gulf of Mexico GLORIA Sidescan Sonar
ArcView data coverages
In July 1982, prior to the EEZ declaration, the USGS conducted a GLORIA survey along the Continental Slope in the northern Gulf of Mexico. Three additional cruises were conducted from 7 August to 22 October, 1985 as an integral part of the EEZ mapping program. Data sets from these cruises were digitally processed (Chavez, 1986) and, for the first time, digitally mosaicked to create maps of the seafloor in the deepwater portion of the Gulf of Mexico (EEZ Scientific Staff, 1985). A total of 16 digital mosaics of a 2 degree by 2 degree (or smaller) area with a 50 meter pixel resolution were completed for the Gulf of Mexico. These individual mosaics were later combined to produce the 250 m overview of the Gulf of Mexico available on this CD-ROM.
Rather than totally re-digitize the interpretation from the 16 digital mosaics, the decision was made to utilize the interpretation image found on USGS Publication DDS-15. The unprojected image was registered to a 250 m Gulf of Mexico composite GLORIA mosaic. The newly registered and projected interpretation was next rasterized creating a file of vector segments of the geologic boundaries. However, due to the stepping nature of the image at geologic boundaries, the vector information also showed stepping. The stepping was more obvious as the user zoomed in to get a closer look at the data set. To smooth the vector information, the boundaries were interactively edited using the vector editing capabilities of the PCI Remote Sensing software package Imageworks. The final vector information was overlayed on the registered GLORIA image for verification and the final vector segments were output in the ARC/INFO export format.
The ARC exported dataset was then imported into ARC/INFO where the ARC polygons were built. No additional editing was done in ARC. The polygon information was then exported as an ArcView shapefile. The shapefile was then processed within ArcView to add the necessary table information for color coding and identification of the various geologic provinces.
An additional ArcView shapefile highlighting Gulf of Mexico features
names is also made available on this CD-ROM. The GIS data coverage
was created from a Microsoft Excel spread sheet found at the National Oceanic
and Atmospheric's National Geophysical Data Center's (NGDC)
Geology & Geophysics website. The information contained in
the spread sheet was edited to include only those features that would pertain
to the planned Gulf of Mexico Internet Map Server for the USGS, Woods Hole
Therefore, this is not a complete listing as would be found from NOAA-NGDC.
|arcvieww.apr||ArcView project file to be used within Netscape for Windows|
|arcviewu.apr||ArcView project file to be used within Netscape for Unix. This project file assumes the CD-ROM has been mounted to the directory /cdrom.|
|arcexplr.aep||ArcExplorer project file to be used within Internet Explorer|
To open the project files, the user must have the appropriate software installed and running on their computer system. For further details on the software requirements, the user may check "What's needed!" page. [an error occurred while processing this directive]