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

relatively flat , butIlma or folds occur where there has been
_ � '�
�t
post-depositional tectonic activity . Such folding is
evident in the Grand '' Hogback , the Little Bookcliffs , the
Uncompahgre Uplift and the Black Canyon of the Gunnison.
Monoclines are the principal structural feature of
the plateau. Most of the monoclines are associated with
uplifts , and represent lines of great vertical shift .
The Grand Hogback lies to the east of the Coal
Basin anticline , which occurs as a small extension at its
southern end . Bedrock units beneath the Coal Basin outcrop
on the Grand Hogback, then dip steeply , far beneath the
mining activity which occurs in the basin . The units are :
the Cretaceous- (Dakolta) formation, the Jurassic- (Morrison
• formations and Entrada sandstones) , and the Permo-Pennsylvania
(Maroon) formations .'
Above the Dakota formation lie younger sedimentary
rocks , which are associated with the Piceance Basin , the
eastward extension o"f the much larger Uinta Basin of extreme
western Colorado and: eastern Utah. The Picear_ce Basir_ lies
on the eastern boundary of the Colorado Plateau physio-
graphic province , adjoining the Southern Rocky Mountain
physiographic province . Coal Basin occurs at the southern
end of the Piceance '"Basin.
The intrusion of Tertiary sills , dikes and laccoliths
has greatly disturbed the area . The Coal Basin anticline is
thought to have been imposed on the Grand Hogback monocline
by a laccolithic intrusion.
I
2