The mine extracts thermal coal from the Anderson and Canyon Seams, with up to 44 and 36 feet, respectively, in thickness.
General Geology and Coal Resources
Stratigraphic units include, in descending order, recent (Holocene age) alluvial and eolian deposits, the Eocene age Wasatch Formation (the overburden), and the Paleocene age Fort Union Formation (which contains the target coal beds). [Dec 2008, Final Environmental Impact Statement, p. 118-120]
Surficial deposits within the general analysis area include alluvial and eolian deposits, clinker, and weathered Wasatch and Fort Union Formations. Although clinker is present in the general analysis area, the tract has no appreciable amounts of clinker. There are thin alluvial deposits along ephemeral streams. These alluvial deposits typically consist primarily of poorly to well-sorted, irregularly bedded to laminated, unconsolidated sand, silt, and clay with minor intervals of fine gravel. The valley floors of Horse Creek, Spring Creek and Antelope Creek contain appreciable amounts of alluvium both in width and depth. The alluvial deposits in Horse Creek, Spring Creek and Antelope Creek contain much more coarse-grained material (sands and gravels) than the ephemeral tributaries that drain most of the general analysis area. [Dec 2008, Final Environmental Impact Statement, p. 118-120]
The Eocene Wasatch Formation forms most of the overburden overlying the mineable coal seams in the genera ........
