National Atlas of the United States 200512 Map Reston, VA National Atlas of the United States <http://nationalatlas.gov/atlasftp.html?openChapters=chpgeol#chpgeol> The color conterminous United States shaded relief data were derived from National Elevation Dataset (NED) data, and show the terrain of the conterminous United States at a resolution of 200 meters. The NED is a raster product assembled by the U.S. Geological Survey, designed to provide national elevation data in a seamless form with a consistent datum, elevation unit, and projection. Data corrections made in the NED assembly process minimize artifacts, permit edge matching, and fill sliver areas of missing data. The color shaded relief images were developed to portray the terrain of the United States. They are intended for visual purposes only. The original NED data must be used for conducting analysis and determining elevation values. The associated world file is included as part of the GeoTIFF. The contents of the world file are: >200.0000 >0.000000 >0.000000 >-200.0000 >-2262900.0000 >1038900.0000 The following projection file can be used when using ESRI's ArcGIS to view the GeoTIFF (any line breaks should be removed): PROJCS["NAD_1983_Lambert_Azimuthal_Equal_Area",GEOGCS ["GCS_Sphere_ARC_INFO",DATUM["D_Sphere_ARC_INFO",SPHEROID ["Sphere_ARC_INFO",6370997.0,0.0]],PRIMEM["Greenwich",0.0], UNIT["Degree",0.0174532925199433]],PROJECTION ["Lambert_Azimuthal_Equal_Area"],PARAMETER["False_Easting",0.0], PARAMETER["False_Northing",0.0],PARAMETER["Central_Meridian", -100.0],PARAMETER["Latitude_Of_Origin",45.0],UNIT["Meter",1.0]] 200209 Date of elevation data download Complete None planned -133 -59 51 19 ISO 19115 Topic Category elevation imageryBaseMapsEarthCover None Digital Elevation Model Shaded Relief Topography Topographic DEM NED None United States Alabama Arizona Arkansas California Colorado Connecticut Delaware District of Columbia Florida Georgia Idaho Illinois Indiana Iowa Kansas Kentucky Louisiana Maine Maryland Massachusetts Michigan Minnesota Mississippi Missouri Montana Nebraska Nevada New Hampshire New Jersey New Mexico New York North Carolina North Dakota Ohio Oklahoma Oregon Pennsylvania Rhode Island South Carolina South Dakota Tennessee Texas Utah Vermont Virginia Washington West Virginia Wisconsin Wyoming None. None. Acknowledgment of the U.S. Geological Survey, Center for EROS and (or) the National Atlas of the United States would be appreciated in products derived from these data. John Hutchinson SAIC Mailing address

USGS Center for EROS

Sioux Falls SD 57198-0001 USA 605-594-6049 hutch@usgs.gov 1-band TIFF format created using ArcInfo 8.3 and then processed through custom software to create the GeoTIFF format. National Atlas of the United States 200512 Reston, VA National Atlas of the United States <http://nationalatlas.gov/atlasftp.html?openChapters=chpgeol#chpgeol> National Atlas of the United States 200512 Reston, VA National Atlas of the United States <http://nationalatlas.gov/atlasftp.html?openChapters=chpgeol#chpgeol> National Atlas of the United States 200512 Reston, VA National Atlas of the United States <http://nationalatlas.gov/atlasftp.html?openChapters=chpgeol#chpgeol> National Atlas of the United States 200603 Reston, VA National Atlas of the United States <http://nationalatlas.gov/atlasftp.html?openChapters=chpgeol#chpgeol> National Atlas of the United States 200603 Reston, VA National Atlas of the United States <http://nationalatlas.gov/atlasftp.html?openChapters=chpgeol#chpgeol> National Atlas of the United States 200603 Reston, VA National Atlas of the United States <http://nationalatlas.gov/atlasftp.html?openChapters=chpgeol#chpgeol> National Atlas of the United States 200603 Reston, VA National Atlas of the United States <http://nationalatlas.gov/atlasftp.html?openChapters=chpgeol#chpgeol> No tests for logical consistency have been performed on this map layer. Data completeness reflects the content of the original NED elevation data. U.S. Geological Survey 2002 1 Sioux Falls, SD U.S. Geological Survey <http://ned.usgs.gov/> Online 2002 Date of elevation data download. National Elevation Dataset Elevation information. National Atlas of the United States 1999 Reston, VA National Atlas of the United States Internal file 1972 1999 Ground condition shorelp020l Shoreline mask for area of coverage. USGS, Center for EROS Unpublished material Internal file 2002 Date of elevation data. ElevationUS_2002 Elevation information. USGS Center for EROS 200509 Map Reston, VA National Atlas of the United States <http://nationalatlas.gov/atlasftp.html?openChapters=chpgeol#chpgeol> Online 200209 Date of elevation data. GrayscaleUS Elevation information. Four elevation mosaics were extracted from the National Elevation Dataset (NED) and used to produce the shaded relief images of the conterminous United States, Alaska, Hawaii, and Puerto Rico and the U.S. Virgin Islands. A separate image was created for each of the four areas because, at 200-meter resolution, file size for an elevation mosaic of all of the United States would exceed the processing capacity of some commonly-used GIS and image processing software packages. For the conterminous United States, elevation data were extracted from the NED and projected to a Lambert Azimuthal Equal-Area (LAZ) projection centered on 100 degrees West, 45 degrees North, with a pixel size of 200 meters. The datum for NED data is NAD83, except for Alaska which uses NAD27. Because there is no ellipsoidal form of the Lambert Azimuthal Equal-Area projection, once data have been projected to LAZ they lose any datum affiliation and instead are based on a sphere with a radius of 6370997 meters. However, some commonly-used software packages will report an error if a datum is not specified, so to accommodate such software, the GeoTIFF for this shaded-relief map layer retains the NAD83 datum associated with the original NED data from which it was derived. Using the ArcInfo Polygrid command, a 0/1 land/water mask was created for the conterminous United States at the same 200 meter resolution as the elevation data, using coastline data clipped from the National Atlas shoreline file. The land/water mask was applied to the 16-bit elevation grid. The masked elevation grid as well as the mask itself is available on request. More information on the NED may be found by following the links at <http://ned.usgs.gov>. A color elevation image was created by slicing the elevation data using the ranges (listed in feet; divide by 3.2808 to get meters) and RGB color values below. >From To index red green blue >--------------------------------------------------- >-250 0 1 220 220 220 >1 249 2 127 159 101 >250 499 3 130 176 112 >500 999 4 160 194 124 >1000 1499 5 185 214 124 >1500 1999 6 207 224 156 >2000 2499 7 223 233 168 >2500 2999 8 241 238 166 >3000 3499 9 237 223 159 >3500 3999 10 240 210 141 >4000 4499 11 230 188 138 >4500 4999 12 216 165 133 >5000 5499 13 197 149 135 >5500 5999 14 217 165 156 >6000 6499 15 227 183 177 >6500 6999 16 223 192 191 >7000 7499 17 239 205 217 >7500 7999 18 244 215 225 >8000 8499 19 243 223 233 >8500 8999 20 248 227 232 >9000 9499 21 248 233 238 >9500 9999 22 246 240 245 >10000 19476 23 255 255 255 >Water 0 132 193 255 > National Elevation Dataset shorelp020l 200212 ElevationUS_2002 ElevationUS_2002 was converted in Adobe Photoshop from RGB to CMY (no black generated). The contrast of GrayscaleUS was enhanced in Adobe Photoshop by using a tritone technique. The enhanced grayscale image was added as a black band to the converted color elevation image to create a CMYK color shaded relief image. The CMYK image was converted in Photoshop to RGB for use in the online National Atlas. In the combined image, the water and non-U.S. land areas no longer had the correct values, so they were reset to meet the requirements of the National Atlas Map Maker. Open water areas were selected using Adobe Photoshop’s magic wand function and set to a RGB value of (132, 193, 255). The same technique was used to select non-U.S. land, and the RGB value was set to (132, 158, 172). The Photoshop image was saved in as a TIFF, ingested into ArcInfo as a grid using the command IMAGEGRID, saved as a TIFF from ArcInfo using the command GRIDIMAGE, and then processed through a USGS GeoTIFF software program to create a fully-compliant GeoTIFF with valid header information. ElevationUS_2002 GrayscaleUS 200508 Raster Grid Cell 17280 25740 Lambert Azimuthal Equal Area -100.00 45.00 0.0 0.0 Row and column 200.0 200.0 Meters None Sphere 6370997.0 1.0 Shaded relief TIFF image grid cell Any of the data elements in the shaded relief file. National Atlas of the United States Shaded relief TIFF image values Color values for the TIFF image. National Atlas of the United States 0 255 Earth Science Information Center, U.S. Geological Survey Mailing address

507 National Center

Reston VA 20192 USA 1-888-ASK-USGS (1-888-275-8747) 703-648-5920 In addition to the address above there are other ESIC offices throughout the country. A full list of these offices is at <http://ask.usgs.gov/esic_index.html>. Although these data have been processed successfully on a computer system at the U.S. Geological Survey, no warranty expressed or implied is made by the U.S. Geological Survey regarding the utility of the data on any other system, nor shall the act of distribution constitute any such warranty. Use of trademarks or formats does not constitute endorsement by the U.S. Geological Survey. There are no copyright restrictions on the use, redistribution, or further processing of this map layer. No responsibility is assumed by the U.S. Geological Survey in the use of these data. TIFF <http://nationalatlas.gov/atlasftp.html?openChapters=chpgeol#chpgeol> There is no charge for the map layer. 20060829 Peg Rawson National Atlas of the United States Mailing address

12201 Sunrise Valley Drive

MS-561

Reston VA 20192 USA 703-648-4183 atlasmail@usgs.gov FGDC Content Standards for Digital Geospatial Metadata FGDC-STD-001-1998 None Unclassified None