2010. National Geophysical Data Center. This line shapefile shows lines of equal annual change (secular variation) in the horizontal component of the total field intensity of the Earth's ... National Atlas of the United States.
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2010. National Geophysical Data Center. This shapefile shows lines of equal annual change (secular variation) in the inclination of the Earth's magnetic field, derived from the Internatio... National Atlas of the United States.
2010. National Geophysical Data Center. This line shapefile shows lines of equal annual change (secular variation), in the total field intensity of the Earth's magnetic field, derived fro... National Atlas of the United States.
2010. National Geophysical Data Center. This line shapefile shows lines of equal annual change (secular variation) in the vertical component of the total field intensity of the Earth's ma... National Atlas of the United States.
2010. National Geophysical Data Center. This shapefile contains isodynamic lines (lines of equal total intensity of the Earth's magnetic field), derived from the International Geomagnetic... National Atlas of the United States.
2010. National Geophysical Data Center. This line shapefile shows lines of equal vertical intensity of the Earth's magnetic field, derived from the International Geomagnetic Reference Fie... National Atlas of the United States.
1999. Geological Survey (U.S.). This line shapefile portrays the major roads in the United States, Puerto Rico, and the U.S. Virgin Islands. The file was produced by joining the i... Geological Survey (U.S.).
1864. Glümer, J. v., Poe, O. M. (Orlando Metcalfe), 1832-1895, Sherman, William T. (William Tecumseh), 1820-1891, and United States. Army. Corps of Engineers. Compiled and drawn by J. v. Glümer. "Julius Bien & Co., lith. N.Y." Relief shown by hachures. Shows location of works erected by Union and Confeder...
1839. Burr, David H., 1803-1875. Detailed map showing relief by hachures, drainage, township and county boundaries, cities and towns, canals, roads, and railroads. From his The Ame... (London], ).
1982. United States. Soil Conservation Service. Shows land use.; Includes vicinity map.; "December 1981 base 4-R-32959." 48 x 57 centimeters Scale approximately 1:100,000. The Service (Athens, Ga.?).