The purpose of the writer is to discuss briefly the salient geologic features relating to the occurrence of gas in the Big Horn Basin structural province. This area includes not only the topographic basin of Big Horn River in Wyoming but also a part of the Clark's Fork drainage basin on the north in Wyoming and Montana, all being structurally one geologic province sometimes referred to in this paper for convenience and brevity simply as the Big Horn Basin. The statements contained herein are based on the writer's knowledge of the various producing gas fields gained from field examinations and office studies during the past 17 years.
The accompanying index map (Fig. 1) outlines the area here described and shows also the location of the numerous gas fields together with their pipe-line outlets. Of these fields, n are in Wyoming; 1, the Dry Creek field, is in Montana.
Natural gas was first utilized in this area in 1909 when the towns of Basin and Greybull were connected to small local supplies long since depleted and not discussed here. Subsequently these towns were connected by pipe lines to larger fields which still produce. The first use of gas from fields here described was in 1911 when the town of Byron was connected with the Garland field. Subsequently, Lovell was added as a market, and Cowley was supplied from the adjacent Byron field.
In the decade 1921–1931 there was a rapid expansion in the development of gas markets so that at the