PERMFILE104624

• Permit No: C1981018
• IBM Index Class Name: Permit File
• Doc Date: 5/13/2002
• Section_Exhibit Name: R2P2 Revised 10/97
• Media Type: D
• Archive: No

'• Observations in the field include slight rolls or folds in the strata with low relief. There are
occasional outcrops with strata exhibiting dips of up to 30 degrees. These dips are confined to small
areas and appear to be the result of differential compaction around lenticular sandstones (channel
sandstones).
' 3.2 General Stratlgraphy
' The rocks exposed throughout the Deserado Mine area are within the Mesaverde Group of Upper
Cretaceous age. These sedimentary beds are well exposed as a southwest facing escarpment
along the flank of the Rangely anticline and along the course of Scullion Gulch and its tributaries.
'
Gaskill and Horn (1959) in an unpublished report on the northeast Rangely coal field describe the
' Mesaverde as °largely composed of yellowish to very light gray, massive, thin bedded and flaggy,
l
t
l
b
fi
fi
i
d
i
i
h
d
l
d
angu
ar
o su
ar, very
angu
ne to
ne gra
ne
quartz san
stone,
nterbedded w
t
san
y gray sha
e,
siltstone and mudstone, carbonaceous shale, coal, and occasional thin often concretionary lenses
' of limey sandstone and sandy limestones.' They state that it appears to be divisible into at least
two units.
' The Mesaverde Group in the mine area has not been previously subdivided on a formational basis.
Throughout much of northwestern Colorado the Mesaverde has been divided into the basal Iles
M Formation, and the overlying Williams Fork Formation, with the contact lying atop the Trout Creek
Sandstone Member of the Iles Formation. The Trout Creek Sandstone has been tentatively
identified east of the mine area near Elk Springs. Mapping by H.L. Cullins (1971) within the Rangely
Quadrangle, identifies the Trout Creek Sandstone equivalent east of Douglas Creek about three
miles southeast of Rangely and seven miles south of the mine area.
It is generally recognized that the principal coal zone within the Mesaverde Group occurs near the
base of the Williams Fork Formation and just above the Trout Creek Sandstone. Coals within the
Iles Formation are known to be thin and laterally discontinuous. The lithology of the Iles Formation
is dominated by laterally continuous sandstones and shales.
Based on this information and on data gathered during field mapping and exploratory drilling, the
strata exposed in the mine area have been subdivided into three zones. In ascending order the
' three zones are the Iles Formation, the Lower Williams Fork Formation, and the Upper Williams Fork
Formation.
' Within the study area, the strata beneath the principal coal zone display a greater abundance of
coarser grained sediments (i.e., sandstones) than does the overlying coal-bearing interval. They
also contain few, if any, significantly thick or continuous coal seams. Therefore, this sequence of
• $