GENERAL33761

• Permit No: C1981021
• IBM Index Class Name: General Documents
• Doc Date: 5/4/1988
• Doc Name: PROPOSED DECISION & FINDINGS OF COMPLIANCE FOR RN1
• Permit Index Doc Type: FINDINGS
• Media Type: D
• Archive: No

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Two normal and one reverse fault exist within the Bourg permit area, at the
nose of the Bourg Syncline. Wyoming Fue] Coal Company has encountered 5
faults at the Canadian Strip Mine. This mine is at the nose of the McCallum
Anticline. However, only 2 normal faults are known to exist in the entire
Marr Strip, which is on the western limb of the McCallum Anticline. To date,
the only faults which produce pit inflows are the faults in the Canadian Strip,
North Park contains 15,000 feet of Triassic to Quaternary aged sedimentary
rocks. Late Cretaceous and Early Tertiary sediments account for almost all of
this total, Figure 4 is a generalized stratigraphic column of the North Park
Coal Field from the Kerr Coal Company permit application.
The Pierre shale is the oldest sedimentary strata exposed in the general area
of the mines. This formation is Late Cretaceous in age and composed of a
4,000 foot thickness of marine shales and minor amounts of silts tone and
sandstone beds. The upper Pierre shale contains a sandstone member which
forms the unconformable contact with the overlying Coalmont Formation. Due to
the marine origin of Pierre shale, the salinity is high in this stratum.
The coal seams of the North Paris area lie in the Coalmont Formation of Early
Tertiary Age. The formation is composed of between 4,000-6,000 feet of
terrestrial interbedded shales, mudstones, sandstones, and coals which
unconformably overlie the Upper Sandstone member of the Pierre Shale
Formation. Three coal seams or zones exist within the Coalmont Formation in
the general area of the mines. These are, in ascending order, the Sudduth
seam, Hoyle seam and Capron seam,
The Sudduth seam is the thickest and most widely mined seam in the region.
fits seam is located at the base of the Coalmont Formation near the
unconformable contact with the Pierre Shale. All three mines in the North
Park Coal Field are mining the Sudduth coal seam. The coal in this seam is a
subbituminus B coal with a low sulfur content (0.25%) and a heat output of
about 10,800 BTU's per pound. The thickness of this seam varies between 10
and 70 feet.
The Hoyle seam is locally discontinuous. This seam will only be mined at the
Bourg Mine where the seam attains a minable thickness of 16 feet. This seam
lies about 80 feet above the Sudduth seam.
The Capron seam is stratigraphicatly located about 2,400 feet above the
Sudduth coal and is commonly split into two beds. The Capron seam is not
currently mined in the North Park Coal Field.
Previous glaciation and stream action have eroded the rock strata down to a
broad alluvial plain. The Canadian River then deposited a 2.0 to 5.0 foot
thick mantle of river alluvium over this erosional surface when the river was
at an elevation of about 8,200 feet. These Upland Terrace deposits have since
become eroded as the Canadian River and its tributaries have become incised.
In the area of the Bourg Mine, these Upland Terrace deposits have been
completely eroded away by Mann Draw. Remnant exposures of the Upland Alluvial
Terrace deposits still cap mesa tops in the area of the Marr Strip and
Canadian Strip.