PERMFILE40846

• Permit No: C1981013
• IBM Index Class Name: Permit File
• Doc Date: 12/11/2001
• Section_Exhibit Name: EXHIBIT 06 HYDROLOGY, GEOLOGY, AND WATER QUALITY
• Media Type: D
• Archive: No

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• '~ quartz sandstone 75 to 125 feet thick with dark gray, carbonaceous shale
locally present near the top of the unit. The Dakota Sandstone, also of
1T early Cretaceous age, rests disconfarmably on the Purgatoire. It is a
J massive quartz sandstone, often exhibiting prominent crossbedding, with
thin interbedded shale.
Its thickness in the study area is estimated at
,
50 to 200 feet. The Graneros Shale rests conformably on the Dakota. It
is a dark gray to black shale with an estimated thickness of 200 feet.
~~ The Cretaceous Greenhorn Limestone intertongues with the underlying Graneros
and consists of 20 to 3p feet of dark gray limestone with minor amounts of
interbedded shale. The Carlile Shale rests conformably on the Greenhorn
• Limestone and is composed of approximately 200 feet of dark gray shale that
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J includes thin sandstones and limestones near the top.
1 The Niobrara formation is upper Cretaceous and commonly divided into
1 the Fart Hays Limes tone, and Smoky Hill Mart members. The Fort Hays Lime-
stone rests conformably on the Carlile and consists of 20 to 30 feet of
grdy limestone and shale. The Smoky Hill member probably exceeds 700 feet
in thickness and is composed of white to buff limestone and marl.
• i
'A
The Pierre Shale consists of a dark gray to black marine shale con-
J taming several thin zones of limestone as well as an upper sequence of
gray to black shale interbedded with buff to gray sandstone. The Pierre
has an estimated thickness of 1800 to 1900 feet in the study area.

The Trinidad formation is a light gray to buff, slightly arkosic sand-
stone that locally contains thin interbeds of shale. The formation.inter-
tongues and is gradational with the underlying Pierre Shale. This fine to
very fine sandstone is often a cliff-former and has a thickness of apmroxi-
mately 250 feet in the study area.
The Vermejo formation conformably overlies the Trinidad. Typically,
the Ve rnejo is made up of three lithologies, buff, gray to gray-green,
slightly arkasic sandstone; gray to black carbonaceous shale; and coal.
The Vermejo thickens rapidly west of Cokedale to over 300 feet.
~ The Cretaceous-Paleocene, Raton formation constitutes the bedrock in
• /~ the study area. It rests unconformably on the Vermejo formation and
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