1987-12-01_PERMIT FILE - C1981017 ‎(172)‎

• Permit No: C1981017
• IBM Index Class Name: PERMIT FILE
• Doc Date: 12/1/1987
• Doc Name: General Description of Geology and Hydrology
• Section_Exhibit Name: Chapter III Section C
• Media Type: D
• Archive: No

indirectly controlled Bear Creek, all forks of Dutch Creek,
• both forks of Oilwell Creek, the south and north forks of
Coal Creek, and Porcupine Creek.
In common with other unroofed laccoliths of
the area, the Coal Basin features , in addition to the dikes ,
a large area of baked shale near the center and numerous
apparently hydrothermal calcite veins .
C . Stratigraphy
The strata of Coal Basin consist , principally ,
of Mancos Shale and the Mesaverde Group , although rocks
varying in age from Pennsylvanian to Tertiary are present .
Coal seams occur above the sandstone units of the Mesaverde
Group . (See Table III-C-1)
Mancos shale floors the vast majority of the
•
basin. It is estimated to be 3 , 000 ' thick. Beneath the
shale , bedrock units are the Cretaceous (Dakota) , Jurassic
(Morrison and Entrada sandstones) , Permian (Weber sandstone)
and Permo-Pennsylvania (Maroon) formations . The bedrock
units outcrop on the -Grand Hogback, then dip steeply beneath
the overlying Coal Basin strata. They occur far beneath ,
and are unaffected by , mining activity .
The Mancos Shale consists of drab . gray ,
sparsely fossiliferous silty shale to shaley siltstone .
Bedding is often difficult if not impossible to detect ,
especially in the upper two-thirds of the formation .
The overlieing Mesaverde formation consists ,
• essentially, of shale beds interspersed with sandstone