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Lake Mohave Geophysical Survey 2002: GIS Data Release
OF 2004-1247


OF 2004-1247 HOME

Disc Contents



Metadata/Data Catalog

References Cited


Getting Started:

This research project integrates seismic-reflection data and sidescan-sonar imagery. These data types have been put into a form easily accessible through a Geographic Information System (GIS). The Environmental Systems Research Institute's ArcView is used as the GIS mapping tool in this particular project. Therefore, the GIS datasets made available are compatible with that software system. The various links to the data not only provide access to the data, but also a discussion of the data format and how the data were collected. How these data are organized may not be necessarily intuitive, so a brief explanation on where to find information will follow. The data can be downloaded from these locations, or from the Metadata/Data Catalog page.

The navigation link points to the ASCII reformatted raw navigation as it was recorded from the GPS system from the cruise. In addition to this form of raw navigation, processed navigation in the form of ArcView shapefiles from the geophysical survey is also available. These include survey tracklines (polylines), and seismic-reflection shotpoint navigation (points).

JPEG images of the seismic-reflection data are available on this CD. These images can be viewed from the Seismic-Reflection page, or as hotlinks within the GIS (see hotlink below).

Sidescan-sonar imagery is provided in the format of georeferenced image mosaics. These mosaics are provided in both TIFF and MrSid formats in NAD 83 geographic coordinates and UTM, Zone 11, NAD83 projection. These data are provided through the Sidescan-Sonar link.

GIS Specifics

An Environmental Systems Research Institute (ESRI) ArcView 3.2 Geographic Information System (GIS) project file resides in the top-level directory of this CD. All associated GIS files are contained in subdirectories under the data directory. The user must have a copy of ESRI ArcView 3.2 or later in order to view the project files. Visit the ESRI website ( for information concerning this and other software.

This project file (mohave.apr) contains a startup script which prompts the user for the drive letter of the CD-ROM drive. This information is needed in order to establish "hotlinks" found within the project file. If the ArcView project file and the data directory are copied to the hard disk - maintaining the original directory hierarchy, then the location entered for the startup script should refer to the directory location of the ArcView project file. If for some reason the directory location is entered incorrectly, then the user can click on the pink button with the yellow CD (Image of a pink button with yellow CD.) to reenter the information.

For those users who do not have ArcView 3.2 or later, the individual GIS data files can still be viewed with a compatible GIS viewer, or a free GIS viewer -ArcExplorer. This GIS data viewer is available from ESRI ( Please note that the ArcExplorer software is limited to the Microsoft Windows operating systems and some UNIX operating systems.

The ArcView project file uses raster image files compressed with MrSid Geospatial Encoder version 1.4. In order to load and view these files, the MrSid Image Support extension must be loaded. This extension will be loaded by default within the project file.

The project file is also setup to "hotlink" to JPEG images of the seismic-reflection profiles. The JPEG (JFIF) Image Support extension must be loaded for this to work. As with the MrSid extension, this extension will be loaded by default within the project file.

All of the shapefiles are in the Geographic NAD83 coordinate system. The georeferenced sidescan-sonar images are available in both the Geographic NAD83 coordinate system, and UTM, Zone11, NAD83 projection. Within the mohave.apr project file, the data loaded into the views are all in the Geographic NAD83 coordinate system.

The seismic survey trackline data presented within the project files are "hotlinked" to JPEG images of the seismic-reflection profiles acquired on those lines. To view these images, click on the lightning bolt () within the project tool bar, and click on an individual trackline within the active seismic trackline theme. The JPEG image of the seismic-reflection profile corresponding to that trackline will be opened in a separate view window so that the user can pan and zoom on the image.


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