Three Remarkable Wyoming Coal Beds
- The Wyodak This coal seam ranges from 25 to 190 feet thick, averaging 100 ft and is the #1 coal producing bed in the nation. It is in the upper part of the Paleocene Fort Union Formation. While the coal bed underlies the entire basin with different names, (over 14 thousand square miles) it is thickest in the Gillette area where it is the Wyodak. The Wyodak surfaces in a narrow north-south band mined by eighteen of the largest open-pit mines in the world. It is subbituminous with an average BTU of 8,220, ash of 6.0%, and sulfur of 0.50 %.
- The Big George The Big George lies below the Lake DeSmet coal bed near Buffalo on the western edge of the Powder River Basin. Because it lies at depths between 1,000 and 2,000 feet, it is not being mined. Big George averages 113 feet thick, often reaching 200 feet. It is in the upper part of the Paleocene Fort Union Formation and connects with the Wyodak coal bed across the basin at Gillette. This was by far the biggest and longest lasting coal swamp of them all accounting for its thickness. The coal is subbituminous with a 9,160 BTU average, ash of 2 to 5%, and sulfur of 0.2 to 0.5 %.
- The Lake DeSmet The thickest coal seam in the United States at 250 feet, it is in the Wasatch Formation of Eocene age and outcrops at Lake DeSmet on the western edge of the Powder River Basin. It is subbituminous with a BTU average of 7,880, ash of 7.6%, and sulfur of 0.6 %. It is currently not being mined.
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