Description: <p><span style="background-color:rgb(255,255,255); color:rgb(74,74,74); font-family:"Avenir Next", Avenir, "Helvetica Neue", sans-serif; font-size:16px;"><span style="display:inline !important; float:none; font-style:normal; font-variant-caps:normal; font-variant-ligatures:normal; font-weight:400; letter-spacing:normal; text-align:start; text-decoration-color:initial; text-decoration-style:initial; text-indent:0px; text-transform:none; word-spacing:0px;">Fenneman and Johnson (1946) categorized 8 broad divisions of the United States, which are subdivided into 25 provinces, which are subdivided again into 82 different sections. This partition was accomplished by examining the underlying geologic structures, the terrain texture, and the present rock types. In this study, we use adjusted versions of the provinces as potential categorical geospatial parameters for our amplification models. In the original physiographic provinces, three provinces cover a significantly larger land mass than the others (e.g. Atlantic Coastal Plain, the Central Lowlands, and the Great Plains). For these three provinces, we use physiographic sections to incorporate geologic and topographic differences that are not captured by the broader provinces and result in regions of approximately equal area.</span></span></p>
Copyright Text: Fenneman, N.M. and Johnson, D.W., 1946, Physiographic divisions of the conterminous U. S: U.S. Geological Survey data release, https://doi.org/10.5066/P9B1S3K8.