"Reconnaissance Map of the United States Showing the Distribution of the Geologic System So Far As Known", U.S. Geological Survey (USGS)

This is the second geological map of the United States published by the USGS. The first edition uses the same base map with the title Map of the United States Exhibiting the Present Status of Knowledge Relating to the Areal Distribution of Geologic Groups. The legend names and color codes thirteen different geological formations in twelve major groups. Compared to the first USGS edition, this map presents new geological information in portions of California and the Pacific northwest. However, the map continues to show wide areas of unmapped territory in the western U.S., thus continuing the Survey's policy of caution in displaying areas that have questionable or incomplete geological data. This approach contrasts sharply with the geological maps of academics such as C.H. Hitchcock, who prepared fully colored maps dating back to the 1870s. On this map the geography of the King, Hayden, Powell and Wheeler surveys are evident in the West.

References:

Condition: A

Folding as issued with slight fold toning, else fine.