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.本数据集为美国本土（conterminous United States）地貌分区（Physiographic Divisions）的多边形覆盖数据。该数据集由芬纳曼编制的1:700万比例尺《美国自然分区图（Physical Divisions of the United States）》经自动化处理生成，该图以1946年确立的8个一级分区、25个地貌省以及86个地貌段为基础，涵盖了具有统一地形特征、岩石类型与构造，以及一致地质和地貌演化历史的典型区域。