Black Canyon of the Gunnison National Park

Black Canyon of the Gunnison National Park is a US national park located in western Colorado. Established in 1999, the park encompasses 30,046 acres (12,159 hectares). It features the canyon, which is up to 2,700 feet (822 meters) deep and was carved by the Gunnison River over a period of about two million years.

The park has been referred to as Colorado's Grand Canyon. Many hikers trek trails along the rim or navigate the steep canyon walls to the river at the bottom. The river is a popular site for kayaking and rafting, but it is quite challenging and only for very experienced watersport adventurers.

The Black Canyon gets its name from the dark gray tones of its rock walls and its heavily shadowed depths. At some points it is relatively wide, while at others the sides press close together. The park is named for Captain John William Gunnison, a nineteenth-century explorer and topographer who was the first person to describe the canyon in writing in 1853.

Background

The steep cliffs of the canyon reveal mostly metamorphic and igneous rock that is about two billion years old. These include granitic rocks, gneiss, schist, and pegmatite. Pegmatite bands formed when hot magma was thrust into cracks in the rocks, where it formed crystals as it cooled. The river began flowing in its present direction and course more than two million years ago. The extreme hardness of the rock allowed it to resist erosion, which caused the river to cut a narrow channel that resulted in steep sides.

During the Mesozoic Era, from 285 to 70 million years ago, the Southern Rocky Mountain and Colorado Plateau regions were covered by sand dunes. The thick layer of sand is evidenced by the Entrada Sandstone layer of pink or yellow rock in the canyon. The Morrison Formation, which originated during the Jurassic period (Mesozoic Era), is a largely sandstone layer that contains numerous dinosaur fossils. More sedimentary rock, the Dakota Sandstone, overlays the Morrison Formation. The Dakota Sandstone is composed of sediment deposited during the Cretaceous period along an inland sea's coast. This sea grew deeper and wider to completely cover Colorado—and a large portion of the Southwest as well—for several thousand years. The mud at its bottom eventually turned to rock, which over time became the Mancos Shale layer. This soft, porous layer contributes to landslides across Colorado and eastern Utah when wet.

The Rocky Mountains were born during the Cenozoic Era, the modern era that began about 70 million years ago. The mountains developed due to the stresses where the North American crustal plate was overriding the Pacific-Farallon Plate, which forced upward thrusts that formed the Southern Rocky Mountains and Colorado Front Range. Some areas experienced volcanic activity, which, in combination with the uplift, created the highland area where the Gunnison River originates. Snowmelt contributed to the establishment of the river's course, which was set about ten to fifteen million years ago. Another uplift, which coincided with the river's development, further entrenched the waters in their course. About two million years ago, the river finished cutting through the volcanic and sedimentary layers. By this time, its course was set, and the river could not redirect through softer stone, so the water slowly chipped away at the much harder layers beneath, creating the narrow chasm of the river valley.

Ute tribes lived around the rim of the Black Canyon for centuries, though archaeologists have found no evidence that they—or any other people—lived within the canyon. Spanish explorers passed through the area during the late eighteenth century, and fur trappers sought beaver pelts in the river. Gunnison's 1853 expedition passed through, conducting a survey for a proposed railroad route. Others later surveyed the river during the nineteenth and early twentieth centuries.

Overview

The region was popular with adventurers during the late nineteenth century, though the river route through the canyon was not navigated until early in the twentieth century. On March 2, 1933, President Herbert Hoover established the Black Canyon of the Gunnison National Monument by presidential proclamation. Hoover cited the educational, scenic, and scientific significance of the canyon. President Franklin D. Roosevelt later expanded the national monument. On October 21, 1999, President Bill Clinton established the Black Canyon of the Gunnison National Park and Gunnison Gorge National Conservation Area.

Erosion continues to carve the rock imperceptibly. The Gunnison River has removed more than 25 cubic miles (104 cubic kilometers) of rock from the canyon. Although the river itself is responsible for wearing down the rock and carrying it away, other factors contribute to erosion. Freezing during the harsh winters, for example, causes rock in the cliff walls to loosen, and gravity helps it to crash into the river, where the water slowly erodes it. Most erosion occurs in spring and early summer, when snowmelt creates high water conditions.

The Gunnison River descends rapidly through its course. It falls about 2,150 feet (655 meters) from Sapinero, the head of the canyon, to its intersection with North Fork 50 miles (80 kilometers) away. The swiftness of the current as it descends increases erosion. At its peak, during high water, the river discharge through the Black Canyon is about 12,000 cubic feet (340 cubic meters) per second.

The park includes a number of geologic regions, ranging from deep canyons to high deserts and pygmy forests. Wildflowers and other plants, including some trees, take root in the walls of the canyon itself. The banks of the river are dotted with boxelder, chokecherry, and narrowleaf cottonwood trees, while aquatic plants grow in the wetlands at the bottom of the canyon. Plants of the pygmy forest, so named for the small size of the trees, include pinyon pine and juniper trees. The canyon rims are lined with Gambel oak trees, serviceberry shrubs, and nut pines. Rabbits and rodents find food and shelter in the shrubs and trees, and the great horned owl preys upon these small mammals. Other common birds include the American dipper, canyon wren, eagle, magpie, mountain bluebird, peregrine falcon, Steller's jay, and white-throated swift. Other creatures include amphibians, coyotes, elk, mule deer, and rainbow and brown trout.

The park offers activities including camping, fishing, hiking, rock climbing, and watersports. Visitors may engage in wildlife watching and take in vistas from several scenic drives. In 2015, the park was designated the nation's ninth International Dark Sky Park. This means light pollution is minimal, allowing stargazers a good view of the skies. The park holds several events throughout the year to serve astronomers.

Bibliography

"Barnes, Susan B. "Black Canyon of the Gunnison National Park: 10 Ways to See the Park." USA Today, 9 May 2016, www.usatoday.com/story/travel/experience/america/2016/05/09/black-canyon-gunnison-national-park-guide/84041884/. Accessed 5 Dec. 2024.

"Black Canyon National Park." City of Montrose Office of Business and Tourism, www.visitmontrose.com/136/Black-Canyon-National-Park. Accessed 5 Dec. 2024.

"Black Canyon of the Gunnison National Park." National Geographic, 5 Nov. 2009, www.nationalgeographic.com/travel/national-parks/black-canyon-gunnison-national-park/. Accessed 5 Dec. 2024.

Hansen, Wallace R. "The Black Canyon of the Gunnison: Today and Yesterday." US Geological Survey, 1965, pubs.usgs.gov/bul/1191/report.pdf. Accessed 5 Dec. 2024.

"John W. Gunnison." Colorado Encyclopedia, coloradoencyclopedia.org/article/john-w-gunnison. Accessed 5 Dec. 2024.

"Life Zones." National Park Service, 13 Nov. 2024, www.nps.gov/blca/learn/nature/lifezones.htm. Accessed 5 Dec. 2024.