The Beacon Flat Formation is named for exposures along Beacon Flat in Sec. 15, T. 33 N., R. 53 E. a few miles east of Carlin, Nevada (Fails, 1960).

The Beacon Flat Formation is Lower Permian (Wolfcampian and Leonardian) in age (Fails, 1960). The Beacon Flat conformably overlies the Buckskin Mountain Formation and is conformably overlain by the Carlin Canyon Formation. The lowest member of the Beacon Flat Formation may be correlative with the upper part of the Carbon Ridge Formation (Fails, 1960).

The Beacon Flat Formation is a poorly exposed unit which can be broken into an upper and lower member with a covered middle interval at the type section at Beacon Flat (Fails, 1960). The lower member is composed of about 555 feet of gray, fine-grained, thin to thick-bedded, silty calcisiltite and calcilutite which are interbedded with gray and tan fine-grained, locally crossbedded calcarenites and gray chert beds and nodules. A 3 foot thick limestone-pebble conglomerate is present in the middle of the unit (Fails, 1960). The middle member is completely covered by alluvium, and is about 1,100 feet thick. The upper member of the Beacon Flat is about 1,140 feet of massive and thick-bedded, gray, fine to coarse-grained calcarenite with abundant fusulinids (10 to 60 percent of the rock), and light gray chert beds and nodules (Fails, 1960). Irregular dolomitization has left 1 to 3 foot thick dark gray, fine-grained dolomitic limestone and dolomite beds interbedded with the typical fine-grained calcarenite.

The Beacon Flat Formation is about 2,800 feet thick at the type section at Beacon Flat, north of Carlin Canyon (Fails, 1960).

The Beacon Flat Formation is exposed along Beacon Flat, north of Carlin Canyon. Depositional Setting

The Beacon Flat Formation represents relatively shallow marine deposition, with local rapid facies changes and conglomerates a result of stream influx.