PERMFILE134568

• Permit No: C1981035A
• IBM Index Class Name: Permit File
• Doc Date: 12/11/2001
• Section_Exhibit Name: 2.04.6 GENERAL GEOLGY DESCRIPTION
• Media Type: D
• Archive: Yes

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Doc Date:1 211 112 0 01 III III I II I IIIIII III
GENERAL
G~/~ GEOLOGY DESCRIPTION
LOCAL GEOLOGY
The local area is characterized by southerly dipping, sedimentary rocks of
have been deeply eroded to the north.
The uppermost formation exposed locally is the Cliff House Formation, w
member of the Mesa Verde Group. It is of marine origin and is composed of irreg
ledges of hard, fine to medium grained, calcareous sandstone in softer argillaceou:
muds[one and silty shale. The top of this formation has been removed by erosion,
thickness of 350 feet. The Cliff House Formation overlies the Menefee Formatior
The Menefee Formation, which is the middle member of the Mesa Verde
a complex assemblage ofcross-bedded sandstones, black shales and coal beds. U~
have been identified by the U. S. Geological Survey. The Menefee Formation has
thickness of 300 feet. The Menefee overlies the Point Lookout Formation.
The Point Lookout Formation, which is the basal member of the Mesa Ver
into two parts. The upper member consists of thick, massive beds ofeven-texture
sandstone. The lower member consists of thin sandstone beds with the Mancos SI
Point Lookout Formation has an average local thickness of 400 feet.
The Mancos Shale, which is exposed approximately four miles north of [ht
of mazine origin and composed of dark-gray to black shale and silty to fine sandy :
amounts of dark-gray argillaceous limestone in lenses. The Mancos Shale has an
thickness of ?000 feet.
The bedding of the above sedimentary rocks dips 2° to 1 I° in a southerly di
the south.
STRATIGRAPHY
The Hesperus azea, located on the northwestern flank of the San Juan Basi
Quatemazy and Cretaceous age. The Quaternary sediments are confined to the val
particular the La Plata River valley along the eastern portion of the area. These dt
poorly consolidated gravels.
The Cretaceous rocks exposed in [he project area consist of Mancos shale,
Mesa Verde Group, and the Lewis shale. The Mancos and Lewis shales are of m~
sediments of the Mesa Verde Group are of transitional to non-marine origin. The
the middle member of the Mesa Verde Group, is the primary coal bearing formati~
MANCOSSHALE
The Mancos shale conformably overlies the Dakota sandstone and is appro:
thick. It consists of dark gray to black shale and silty to fine sandy shale with smal
gray argillaceous limestone in lenses and concretions which weather to a bright yel
2.04.6 page 1
age which
ich is the upper
filar [o lenticular
fine sandstone,
eaving an avera e
~oup is composed of
to seven coal seams
Group, is divided
medium-grained
e below. The
King Coal Mine, is
sale with small
deraee local
flattening [o
contains rocks of
bottoms and in
sits are primarily
coal bearing
origin and the
refee formation,
imately 2,000 feet
amounts of dazk-
ow brown color.
November 1993