7386

• UCREFRP Catalog Number: 7386
• Author: National Park Service.
• Title: Resource/Boundary Evaluation for Lands Adjacent to Black Canyon of the Gunnison National Monument, Colorado.
• USFW Year: 1990.
• USFW - Doc Type: Washington, D.C.
• Copyright Material: NO

APPENDIX A

United States Department of the

GEOLOGICAL SURVEY
BOX 25046 M.S. q 11
DE!'lVER FEDERAL CENTER
DENVER. COLORADO 80225

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TAICI -
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Intenor AMERKA~-'-
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BLACK ~.~.;~~~

Mr. John E. Welch
Superintendent
Black Canyon of the Gunnison National Monument
P.O. Box 1648, Highway 50 East
Montrose, Colorado 81402-1648

FE8 2 1 1989
F~bruary 16, 1989
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Dear Mr. Welch:

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Thank you for inviting me to respond to your letter of February 3 and to
express my views about the reach of the Black Canyon downstream from the
monunent boundary to the North Fork. My views are about the same now as
stated in my July 1967 article in National Parks Magazine. That article
was reprinted in the Congressional Record at the request of the tate
Senator Peter Dominick of Colorado. This reach of canyon shares many of
the attributes of the monument, but in many ways it is much different,
particularly with respect to the sedimentary cap rocks, whiCh are poorly
exposed ir the monument but are exceptionally well exposed downstream.
These rocks, Jurassic and Cretaceous in age, add a scenic and geologic
aspect to that part of the canyon that is essentially nonexistent in the
monument.

Both sections of the canyon,however, are integral parts of one huge
physiographic entity and they complement one another rather than compp.te.
Neither section alone tells the whole story. The whole Black Canyon is
truly a world-class gorge, among the best that America has to offer the
visiting public, and the geologic story is incomplete witho~t reference to
its downstream section.

One of the cost significant geologic attributes of the downstream section
of the canyon is the extent and display of large-scale faulting and the
relationship of faulting to the geologic history of the Gunnison Uplift and
the canyon itself. This concept Clay at first seem abstruse" but because of
the excellence of the exposure, one need not be a professional geologist to
appreciate and readily grasp the meaning of the faulting. On several
occasions, having pointed out the salient'features, I have had the pleasure
of seeing visitors' faces light up with recognition and intellectual
excitement.

The large Ute Indian Fault Zone, a case in point, Is exposed south to north
about 8 miles, mostly in striking view of the river and rims of the
canyon. Here, close at hand, the visitor can gain insights into the
character, mechanics, causes, and meanings of past earth movements and how
they affect the evolution of the landscape. One can safely say that the
display of this fault zone is among the most straightforward in the United
States.

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