Abstract: This report is a supplement to the report, "Effect of pumpage on ground-water levels as modeled in Laramie County, Wyoming," published as U.S. Geological Survey Water-Resources Investigations Open-File Report 80-1104 which describes ground-water conditions in post-Cretaceous rocks in Laramie County. The computer program and the data used to model ground-water conditions in post-Cretaceous rocks in Laramie County are listed in this report.

Abstract: "Precambrian metavolcanic rocks north and south of the village of Granite, Wyoming, belong to a sequence of isolated metavolcanic and metasedimentary masses in the Sherman Granite of the southern Laramie Mountains. Similar rocks lie to the west, in the Precambrian uplifts of the southern Medicine Bow Mountains and Sierra Madre. A major fault system, the Cheyenne belt, splits these two ranges into northern and southern domains, and may constitute a suture along which Early Proterozoic islands arcs collided with an Early Proterozoic passive margin. Projection of the Cheyenne belt into the Laramie Mountains suggests that the study area, which is 65 kilometers south of the proposed suture, comprises a distinct volcanic arc with a unique chemistry or age. However, chemistry of the volcanic rocks of the study area as determined as so far does not differ significantly from those of the Medicine Bow Mountains and Sierra Madre."