U.S. Geological Survey Open-File Report 2009-1150
Surficial Geology of the Floor of Lake Mead (Arizona and Nevada) as Defined by Sidescan-Sonar Imagery, Lake-Floor Topography, and Post-Impoundment Sediment Thickness
The focus of this report is the release of the interpretation of the surficial geology of Lake Mead. This interpretation is largely based on previously published data (Twichell and others, 2003) including sidescan-sonar imagery, lake-floor topography, and post-impoundment sediment thickness. As a courtesy and convenience, these previously published datasets are also available as a part of this report. The description of the GIS data layer indicates if the dataset was previously published.
This report contains geospatial data in either vector or raster format. The vector data are available in Environmental Systems Research Institute (ESRI) shapefile format. Shapefiles generally include *.shp, *.shx, and *.dbf files at a minimum. All of these data files also include the *.prj files, which contain the dataset projection information. The raster data are either ESRI binary grid format or GeoTIFF image format. A TIFF world file also accompanies the GeoTIFF images in case the user does not have software capable of reading the registration information from the GeoTIFF header.
For the sake of brevity, only the filename prefix has been included in the column 'Filename' listed below; extensions have been excluded. Clicking on the listings in the 'Filename' column will display a thumbnail image of the dataset.
Federal Geographic Data Committee (FGDC) compliant metadata are available for all the data contained in this report. Each dataset has metadata available in several formats. The information contained within each file is the same but is presented differently to help make the information more user friendly. The text, HTML, and FAQ versions of the metadata have links to those files, provided below.
The files necessary to load each dataset have been compressed into a single WinZip® file, along with all format types of the metadata. This includes the XML metadata format generated and viewable by ArcCatalog. These data files can be downloaded directly from the CD-ROM or from the table below. To download the data from the table below, right mouse click on the link in the 'Download' column. Select 'Save Target As...' to save a compressed WinZip® file to the local hard drive. If WinZip® is not currently installed on the local system, go to WinZip® (www.winzip.com) to download the latest version of the utility.
When this report is accessed from the CD-ROM, the top level of the report contains an ArcView 3.3 project file (lakemead_interp.apr) and an ESRI ArcMap 9.2 document (lakemead_interp.mxd). These files contain the data layers of this report already loaded.
|lakemead_interp||Polyline shapefile of the interpretation of the surficial geology of the floor of Lake Mead based on sidescan-sonar imagery, topography, and sediment thickness. Geographic coordinate system, WGS84||
|hydro_l||Polyline shapefile from the National Atlas of the United States that displays hydrographic features such as coastlines, lake shorelines, rivers and streams.||
|lakebnds||Polygon shapefile marking the bounds of Lake Mead when at full capacity (approximately 375 meter elevation). Previously published in Twichell and others (2003).||
|preshsh_g||TIFF image of the hillshade surface representing the present day floor of Lake Mead and the surrounding area. Previously published in Twichell and others (2003).||
|statesp020||Polygon shapefile from the Nation Atlas of the United States providing the State boundaries.||
|isogrdgeog||Isopach ESRI binary grid of post-impoundment sediment in Lake Mead - Geographic Coordinate system, NAD83. Previously published in Twichell and others (2003).||
sidescan-sonar imagery (gis/sidescan)
|bbasinenh_g||Enhanced GeoTIFF sidescan-sonar mosaic of Boulder Basin, Lake Mead. Geographic coordinates, WGS84. Previously published in Twichell and others (2003).||
|lvwash_eng||Enhanced GeoTIFF sidescan-sonar mosaic of Las Vegas Wash, Lake Mead. Geographic coordinates, WGS84. Previously published in Twichell and others (2003).||
|overtonenh_g||Enhanced TIFF sidescan-sonar mosaic of Overton Arm, Lake Mead. Geographic coordinates, WGS84. Previously published in Twichell and others (2003).||
|tempiceenh_g||Enhanced TIFF sidescan-sonar mosaic of the area of Lake Mead east of Virgin Basin (includes Temple Basin and Gregg Basin). Geographic coordinates, WGS84. Previously published in Twichell and others (2003).||
|vbasinenh_g||Enhanced TIFF sidescan-sonar mosaic of Virgin Basin, Lake Mead. Geographic coordinates, WGS84. Previously published in Twichell and others (2003).||