2011-11-28_PERMIT FILE - C1992081 ‎(36)‎

• Permit No: C1992081
• IBM Index Class Name: Permit File
• Doc Date: 11/28/2011
• Section_Exhibit Name: TAB 06 GEOLOGY
• Media Type: D
• Archive: No

• TAB 6
GEOLOGY
Geologic Description
Regional Structure. The Hayden Gulch Terminal is situated immediately north of the rugged
Yilliame Fork Mountains which ere within the southeastern synclinal portion of the Sand
Yeah structural basin in northern Colorado and central Yyoming (Bess et el., 1955). In
northern Colorado, the synclinal portion of the Send Yash basin is bordered on the
southwest by the Axial Basin anticline, end on the east by the Park Range anticline.
Numerous folds modify the synclinal structure of the region, the largest of which is the
Tow Creek anticline located approximately 8 miles east of the mine permit Brea (Figure
6-1). The Tow Creek anticline as well es the area that lies approximately 11 miles to the
south of it are heavily faulted. No known faults occur within the immediately vicinity of
the Hayden Gulch Terminal site.
Regional Stratiaraohv. The exposed rock sequence in the region consists primarily of
about 13,500 feet of Lete Cretaceous, Tertiary, and guaternery age sedimentary deposits.
• S
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1955) occur regionally. The largest regional occurr ence of extrusive rocks occurs in the
Flat Tops about 25 miles south of the Hayden Gulch Terminal permit area.
The oldest rock formation outcropping in the region is the Maneos shale of Late Cretaceous
age. The nearest outcrop to the Hayden Gulch Terminal is about eight miles south of the
permit area along Sege Creek. The Mencos shale is about 4,900 feet thick end is
conformable with the overlying Mesaverde group end the underlying Dakota sandstone (Bass
et al., 1955). The Nencos shale is predominately a dark-gray marine shale with interbedded
layers of sandstone near the top and interbedded layers of sandstone and limestone near
the base. There is a sandstone layer about 50 feet in thickness situated approximately
300 feet above the base of the formation which is thought to be equivalent to part of the
Frontier sandstone (Bass et al, 1955). Above the Mencos Shale lies the Mesaverde Group,
also of late Cretaceous age. This group consists of two formations, the oldest being the
Iles formation and the youngest being the Yilliame Fork Formation (Figure 6-1). Together
these two formations represent about 2,550 to 3,550 feet of sandstone interbedded with
shales, sandy shales, and coal (Bess et el, 1955).
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