The mountain ranges of the Middle Rocky Mountain region represent a peculiar structural type—elongated uplifts alternating with basins—combining features characteristic of block faulting and of folding. The relative simplicity of structural design and the juxtaposition of the ranges with basins of considerable depth render this region well suited for studies looking toward a solution of some of the larger problems of crustal deformation.
With the structural framework of the Bighorn Basin as the object of intensive study from every angle, a comprehensive research project was launched in 1930 under the leadership of W. T. Thom, Jr., of Princeton University. The facts of geologic structure and of geophysical behavior were made the center of the program, with comprehensive and integrated studies of stratigraphy and paleontology, of physiography, and of igneous petrography furnishing a fuller basis for interpretations in terms of geologic history, and, . . .