These layers are clipped from 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.

These layers are clipped from 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.