Lower Tertiary coal bed distribution and coal resources of the Reno Junction-Antelope Creek area, Campbell, Converse, Niobrara, and Weston counties, Wyoming

The Powder River Basin of Wyoming and Montana contains some of the world's most extensive deposits of low sulfur subbituminous coal.  The major coal beds occur in the upper part of the Fort Union and lower part of the Wasatch Formations of early Tertiary age (deposited about 60 to 50 million years ago).  Most of the coal beds have been given informal names by local workers; names used in the Reno Junction-Antelope Creek area are shown on the fence diagram and on the sample well logs (fig. 1).  Conditions leading to the formation of these coal deposits in the geologic past are discussed by R. W. Brown (1958, 1962).