Surface and subsurface data of an area along the eastern margin of the Idaho-Wyoming thrust belt establish the geometry and times of movement of two major frontal thrust faults.

New subdivisions of the 7,000-foot-thick continental Evanston, Wasatch, Green River, and Fowkes Formations facilitate understanding of sediment genesis and Wyoming thrust-belt tectonic events.

Geophysical data indicate the thickness of Cenozoic sedimentary rocks and the dsitribution, and locally the thickness, of igneous rocks.

Contrasts in rock sequences in the Bancroft, Soda Springs, and Preston quadrangles require new units for, and modified usages of, the names Brigham, Langston, and Ute. -- Description from title page.