Black Canyon of the Gunnison National Park
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| Black Canyon of the Gunnison | |
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| IUCN Category II (National Park) | |
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| Location: | Colorado, USA |
| Nearest city: | Montrose, CO |
| Coordinates: | |
| Area: | 32,950 acres (133 km²) |
| Established: | October 21, 1999 |
| Total Visitation: | 180,814 (in 2005) |
| Governing body: | National Park Service |
Black Canyon of the Gunnison National Park is a United States National Park located in western Colorado. There are two entrances to the park which are managed by the National Park Service. The more developed south rim entrance is located 15 miles (24 km) east of Montrose. The north rim entrance is located 11 miles (18 km) south of Crawford and is closed in the winter. The park is 47 mi² (122 km²) in size. The entire canyon is approximately 48 miles long, 12 miles of which are located in the national park. The national park itself contains the deepest and most dramatic section of the canyon, but the canyon continues upstream into the Curecanti National Recreation Area and downstream into the Gunnison Gorge National Conservation Area.
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[edit] Geology
The Gunnison River drops an average of 95 feet per mile (18 m/km) through the national park, making it one of the steepest river descents in North America. In comparison, the Colorado River through the Grand Canyon drops an average of 7.5 feet per mile (1.4 m/km). At its steepest, the Gunnison River drops 480 feet (150 m) through one 2 mile (3 km) section.[1].
The Black Canyon gets its name on account of its steepness. This steepness makes it difficult for sunlight to penetrate very far down the canyon. As a result, the walls of the canyon are most often draped in shadows, causing the rocky walls to appear black. At its narrowest point the canyon is only 40 feet (12 meters) across at the river.[2]
The extreme steepness and depth of the Black Canyon formed as the result of several geologic processes acting together. The Gunnison River is primarily responsible for carving the canyon, though several other geologic events had to occur in order to form the canyon as it is seen today.
[edit] Precambrian
The Precambrian gneiss and schist that makes up the majority of the steep walls of the black canyon formed 1.7 billion years ago during a metamorphic period brought on by the collision of ancient volcanic island arcs with the southern end of what we now know as Wyoming. The lighter-colored pegmatite dikes that can be seen crosscutting the basement rocks formed during this period as well.[3] .
[edit] Cretaceous - Tertiary
The entire area underwent uplift during the Laramide orogeny between 70 and 40 million years ago. The Gunnison Uplift is an example of this event. This raised the Precambrian gneisses and schists that make up the canyon walls. During the Tertiary from 26 to 35 million years ago large episodes of volcanism occurred in the area immediately surrounding the present day Black Canyon. The West Elk Mountains, La Sal Mountains, Henry Mountains, and Abajo Mountains all contributed to burying the area in several thousand feet of volcanic ash and debris.[4] .
The modern Gunnison River set its course 15 million years ago as the run-off from the nearby La Sal and West Elk Mountains and the Sawatch Range began carving through the relatively soft volcanic deposits.[4]
[edit] Quaternary
With the Gunnison River’s course set, a broad uplift in the area from 2 to 3 million years ago caused the river to cut down through the softer volcanic deposits. Eventually the river reached the Precambrian rocks of the Gunnison Uplift. Since the river was unable to change its course, it began scouring through the extremely hard metamorphic rocks of the Gunnison Uplift. The river’s flow was much larger than currently, with much higher levels of turbidity. As a result the river dug down through the Precambrian gneiss and schist at the rate of 1 inch every 100 years. The extreme hardness of the metamorphic rock along with the relative quickness with which the river carved through them created the steep walls that can be seen today.[4]
A number of feeder canyons running into the Black Canyon slope in the wrong direction for water to flow into the canyon. It is believed that less-entrenched streams in the region have shifted to a more north-flowing drainage pattern in response to a change in the tilt of the surrounding terrain. The west-flowing Gunnison, however, was essentially trapped in the hard Precambrian rock of the Black Canyon and could not change its course.
[edit] Biology
Plants native to the park include: Aspen, Ponderosa pine, Sagebrush, desert mahogany, Utah Juniper, Gambel oak (scrub oak), and Singleleaf Ash.
Some birds that live in the park are: Great Horned Owl (resident), Mountain Bluebird (migratory), Steller's jay (resident), Peregrine falcon (migratory), White-throated Swift (migratory), Canyon Wren (migratory), American Dipper (resident).
[edit] Attractions
The main attraction of the park is the scenic drive along the south rim. There is also a campground and several miles of hiking and nature trails. The river can be accessed by a steep, unmaintained trail that takes about 4 hours to hike down and 6 to hike back.
The "Black" is a center for rock-climbing in the United States. First ascents were done by Layton Kor, Huntley Ingalls and others starting about 1960. The main climbing walls are 1800 feet (550 meters) tall, and feature steep face climbing and cracks on often poor rock with difficult protection. The Black is an area known for its seriousness and traditional climbing values.
Rafting opportunities also exist in the Canyon. In the national monument itself, several impassable stretches of water block navigation, where the river roars under huge rocks and over massive cataracts. Portaging these areas is the only way to run the river. The boats and gear must be carried for several miles through steep, rocky terrain littered with poison Ivy. The remaining rapids are Class IV (advanced) and Class V (expert) rated. For this reason, only the most experienced boaters run the monument secton. Downstream from this the river mellows just a bit, in the Gunnison Gorge National Conservation area. The river here is still very remote with many large rapids up to Class IV. Despite being easier than the upper section, this section is still for experienced boaters only. Most of both areas are accessible by boat only, making a float trip down this river one of the most incredible wilderness experiences in North America.
[edit] History
The area was established as a U.S. National Monument on March 2, 1933 and made into a National Park on October 21, 1999.
[edit] Music
Black Canyon of the Gunnison is also a symphonic composition by Frank Erickson, which has been performed on the rim of the canyon.
[edit] References
- ^ Black Canyon of the Gunnison National Park- The Geologic Story. National Park Service (2006-7-25). Retrieved on October 27, 2006.
- ^ Black Canyon of the Gunnison National Park- Things To Know Before You Go. National Park Service (2006-9-5). Retrieved on October 27, 2006.
- ^ Tweto, O (1980). Colorado Geology. Rocky Mountain Association of Geologists, 37-46.
- ^ a b c Trista Thornberrry-Ehrlich (2005). "Black Canyon of the Gunnison National Park & Curecanti National Recreation Area: Geologic Resource Evaluation Report" (PDF). Retrieved on 2006-10-27.
- Black Canyon National Park, Colorado. NASA Earth Observatory. Retrieved on May 5, 2006.
[edit] External links
- official site: Black Canyon of the Gunnison National Park
- Gunnison Tourism Office (official tourism website)
- Details on how the canyon was formed
- Geology and photo gallery of Black Canyon
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