2010-02-24_REVISION - C1996083 ‎(2)‎

• Permit No: C1996083
• IBM Index Class Name: Revision
• Doc Date: 2/24/2010
• Doc Name: Complete Text Submittal - Letter, TOC, 2.03 & 2.04
• Type & Sequence: PR12
• Media Type: D
• Archive: No

2.04.6
seven cycles of marine - nonmarine deposition in the Eastern Piceance Basin.
The coal deposits of the area were deposited as the complex relationships of
deltaic, fluvial, and barrier island facies were intermittently modified by
transgressive- regressive cycles of the retreating Cretaceous shoreline.
The coal bearing member of the Mesaverde formation locally contains up to
nine mineable coal seams in the North Fork Valley, named in ascending
alphabetical order, within the stratigraphic interval 500 to 600 ft. above the
Rollins Sandstone Member (Dunrud, 1976). Mines recently operating in the
various coal seams are as follows: Somerset - C & B -2; Sanborn Creek - C &
B -2; Bowie No. 1 - D -2; Blue Ribbon and Hawks Nest - E -1; Bear - C & B -2;
Mountain Coal Company - F & B -2. Due to the depositional environment of
the coal bearing member, individual coal seams are not laterally continuous
nor do they maintain uniform thicknesses from differing locations throughout
the area.
The barren member of the Mesaverde formation is lithologically similar to the
coal bearing member with the exception of virtually no mineable coal seams.
In the North Fork area, the barren member is stratigraphically between the F
coal seam and the Ohio Creek conglomerate, and was estimated by Lee
(1912) to be 1500 ft. thick. The scarcity of coal deposits within the barren
member probably represents progradation of terrigenous; nonmarine
sediments deposited in response to the retreating shoreline. Hail (1972)
reports maximum thickness of the entire Mesaverde Formation to be about
2300 ft.
The Paleocene Ohio Creek Formation unconformably over lies the
Mesaverde formation. The Ohio Creek Formation consists of light -gray,
locally conglomeratic sandstone which ranges in thickness from locally 0 ft.
to a maximum of 200 ft. Where the conglomeratic facies is lacking or
obscured by surficial deposits, the Ohio Creek Formation is mapped within
the Mesaverde Formation (Hail, 1972).
The Eocene Wasatch Formation consists of variegated mudstone and
siltstone with interbedded medium gray lenticular sandstone, which is locally
conglomeratic (Junge, 1978). Maximum thickness is reported to be
approximately 1600 ft. (Hail, 1972), although exposures are largely obscured
PR-12 2.04-15- 02/10