This multi-scale geologic map service is a partial representation of the digital data for the Geologic Map of North America. Geologic units and faults, clipped to the terrestrial extent of North America, are represented here. The major divisions of geologic time (stratigraphic age) are represented with the RGB equivalent of the CMYK color specifications presented in the FGDC Digital Cartographic Standard for Geologic Map Symbolization. Faults are represented with a solid (fault location accurate), dashed (fault location approximate) or dotted (concealed fault) line.
Digital data and other resources for the Geologic Map of North America are available online at http://ngmdb.usgs.gov/gmna/.