This data set is a portion of a statewide geology database, which is being compiled by the U.S. Geological Survey's National Survey and Analysis (NSA) project, whose goal is to compile geologic, geochemical, geophysical, and other data.
Each map unit has been assigned an NSACLASS value (4 5 B). NSACLASS is a numeric code used for compilation geologic mapping for the state of Alaska. This data set represents a generalized map, thus it is possible that a geologic unit is made of multiple NSACLASS values.
NOTE: Because of the limitations of common GIS fonts, the letters "C", "pC", "Mz", "P", "Pz", "Tr" are substituted for the standard symbols for "Cambrian", "Precambrian", "Mesozoic", "Proterozoic", "Paleozoic", and "Triassic." The letters "C" (Carboniferous and Cambrian) and "P" (Permian and Proterozoic) have multiple age designations, so the user should refer to the geologic unit descriptions for the correct geologic age.