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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.
2011. World Data Center for Paleoclimatology and NOAA Paleoclimatology Program (U.S.). This line shapefile represents the maximum pleistocene glacier limits (extent). This report is an update of the Alaska PalaeoGlacier Atlas. It incl... World Data Center for Paleoclimatology.
2003. Geological Survey (U.S.) Minerals Information Team. This point shapefile represents ferrous metal processing plants in the United States. The data represent commodities covered by the Minerals Inform... National Atlas of the United States.
2003. Geological Survey (U.S.) Minerals Information Team. This point shapefile includes nonferrous metal processing plants in the United States. The data represent commodities covered by the Minerals Infor... National Atlas of the United States.
2003. Geological Survey (U.S.). Water Resources Division. Wisconsin District. This polygon shapefile contains the shallowest principal aquifers of the conterminous United States, Hawaii, Puerto Rico, and the U.S. Virgin Islan... Geological Survey (U.S.).
2003. Geological Survey (U.S.) Minerals Information Team. This point shapefile represents the locations of refractory, abrasive, and other industrial minerals operations in the United States. The data repr... National Atlas of the United States.
2002. Geological Survey (U.S.) Minerals Information Team. This point shapefile includes sand and gravel operations in the United States. These data were obtained from information reported voluntarily to th... National Atlas of the United States.