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'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 while the north rim entrance is located 11 miles (18 km) south of Crawford and is closed in the winter. The park, which is 47 mi² (122 km²) in size, contains 12 miles of the 48 mile long canyon. 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.

Contents

Geology

Precambrian

Cretaceous - Tertiary

Quaternary

History

Biology

Attractions

References

External links

Geology

The Gunnison River drops an average of 43 feet per mile (8 m/km) through the entire canyon, 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). The greatest descent of the river occurs in the park at Chasm View dropping 240 feet per mile (45 m/km).^[1] The Black Canyon is so named on account of its steepness which 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.^[3]

Painted Wall on the north side of the canyon. It is the highest sheer cliff in Colorado at 2250 feet (685 m). Lighter-colored pegmatite dikes are clearly visible.

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.^[4]

Cretaceous - Tertiary

The entire area underwent uplift during the Laramide orogeny between 70 and 40 million years ago which was also part of the Gunnison Uplift. 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.^[5]
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.

Black Canyon from Tomichi Point

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.
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.^[6]

Black Canyon from Kneeling Camel View

History

The Ute Indians had known of the canyon to exist for a long time before the first Europeans saw it. By the time the United States gained independence in 1776, two Spanish expeditions had passed by the canyons. In the 1800s, the numerous fur trappers searching for beaver pelts would have known of the canyon's existence but they left no written record. By the late 1800s and into the early 1900s, the canyon had been thoroughly explored and while the first explorers came for commercial success and wealth, the later visitors came to see the canyon as an opportunity for recreation and personal enjoyment.^[7]
The area was established as a U.S. National Monument on March 2, 1933 and made into a National Park on October 21, 1999.^[8]

Biology

The Black Canyon of the Gunnison National Park contains a wide variety of flora and fauna. Some common plants that are native to the park include Aspen, Ponderosa pine, Sagebrush,
Desert Mahogany, Utah Juniper, Gambel oak (scrub oak) and Singleleaf Ash.^[9]
Wildlife in the park include coyotes, elk, magpies, eagles, and the mule deer. In addition the canyon is the home of a number of resident birds including the Great Horned Owl, the American dipper and Steller's Jay and migratory birds such as the Mountain Bluebird, the Peregrine Falcon, the White-throated Swift and the Canyon Wren.^[10]

Attractions

The narrowest part of the Black Canyon, looking down from Chasm View at twilight.

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 north rim is also accessible by automobile, though it is somewhat more remote. There is a small primitive campground. The river can be accessed by a steep, unmaintained trail that takes about four hours to hike down and six to hike back. The canyon is also a center for rock-climbing in the United States. Many of the climbs are difficult and are only done by advanced climbers. The canyon is an area known by climbers for its traditional climbing values.^[11] While some rafting opportunities do exist within the canyon, severe gradients and the diversion of most of the river's flow to other watersheds produce several impassable stretches of water within the national park, hindering navigation, even for extreme whitewater enthusiasts.^[12]

References

1. Black Canyon Dimensions
2. Black Canyon of the Gunnison National Park- Things To Know Before You Go
3.
Black Canyon of the Gunnison National Park- The Geologic Story
4. Colorado Geology, , O, Tweto, Rocky Mountain Association of Geologists, ,
5.
6.
Black Canyon of the Gunnison National Park : From Past to Present

7. BCOTGNP : History & Culture : Animals
8. Cornell University Law School - US Code Collection
9. Black Canyon of the Gunnison National Park : Plants
10. Black Canyon of the Gunnison National Park : Animals
11. Black Canyon of the Gunnison National Park : Rock Climbing
12. Black Canyon of the Gunnison National Park : Rafting

External links

★ Black Canyon of the Gunnison National Park (official site)

★ Geology and photo gallery of Black Canyon

★ Chicago Tribune - A slash in the mesa