Summary of airborne radiometric surveys of certain sediments in Bighorn Basin, Wyoming, and Montana

A preliminary map showing the lithology of parts of the Powder River Basin, Wyoming.

From introduction: This is a progress report on regional stratigraphic and paleontologic studies of the Upper Cretaceous Montana Group and equivalent rocks in the northern part of the western interior of the United States. It presents preliminary data on the positions of strandlines during a 14-m.y. (million year) span of the Late Cretaceous as well as our interpretations of the geologic history of this period.

Script from the WBAP-TV/NBC station in Fort Worth, Texas, relating a news story of forest fire has been reported in at least six western states. Also, at least 13 major fires have been reported out of control in California, Montana, Oregon, Washington, Wyoming and Idaho.

Abstract: A digital simulation model was used to analyze regional ground-water flow in the Madison Group aquifer in the Powder River Basin and adjacent areas. Most recharge to the aquifer originates in or near the outcrop areas of the Madison in the Bighorn Mountains and Black Hills , and most discharge occurs through springs and wells. Results from the model calculations indicate that the total flow through the aquifer in the modeled areas was approximately 200 cubic feet per second (5.7 cubic metres per second). The aquifer can probably sustain increased ground-water withdrawals probably would significantly lower the potentiometric surface in the Madison aquifer in a large part of the basin. The digital model could better predict the effects of withdrawals if more accurate estimates of the storage coefficient, transmissivity, and leakance could be obtained.

This report contains data from a survey taken between August 11 and August 27, 1978 on the high sensitivity airborne gamma-ray spectrometer and magnetometer over the Ashton quadrangle in Idaho, Montana, and Wyoming.

Averaged record data listings taken during aerial gamma-ray and magnetic surveys of the Ashton quadrangle in Idaho, Montana, and Wyoming.

Single record data listings taken during aerial gamma-ray and magnetic surveys of the Ashton quadrangle in Idaho, Montana, and Wyoming.

The following report is the first in a series of volumes presenting data recorded during the months of August and September, 1978, from a radiometric and magnetic survey taken in four quadrangles between Wyoming and southern Montana (Forsyth, Hardin, Sheridan, Arminto, Newcastle and Gillette)