Physiographic divisions of the conterminous U. S.

This is a polygon coverage of Physiographic Divisions in the
conterminous United States. It was automated from Fenneman's
1:7,000,000-scale map, "Physical Divisions of the United
States," which is based on eight major 1946 divisions, 25 provinces,
and 86 sections representing distinctive areas having common
topography, rock types and structure, and geologic and
geomorphic history.