"[3] The Gunnison River drops an average of 34 feet per mile (6.4 m/km) through the entire canyon, making it the 5th steepest mountain descent in North America.

The greatest descent of the Gunnison River occurs within the park at Chasm View dropping 240 feet per mile (45 m/km).

[6] The Precambrian gneiss and schist that make 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 is present-day Wyoming.

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.

[8] 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.

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.

It is believed that less-entrenched streams in the region shifted to a more north-flowing drainage pattern in response to a change in the tilt of the surrounding terrain.

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.

The first official account of the Black Canyon was provided by Captain John Williams Gunnison in 1853, who was leading an expedition to survey a route from Saint Louis and San Francisco.

Following his death at the hands of the Ute later that year, the river that Captain Gunnison had called the Grand was renamed in his honor.

The line was built to provide a link to the burgeoning gold and silver mines of the San Juan mountains.

It took over a year for Irish and Italian laborers to carve out a 15-mile (24 km) roadbed from Sapinero to Cimarron, costing a staggering $165,000 per mile.

[14] Rudyard Kipling described his 1889 ride through the canyon in the following words: We entered a gorge, remote from the sun, where the rocks were two thousand feet sheer, and where a rock splintered river roared and howled ten feet below a track which seemed to have been built on the simple principle of dropping miscellaneous dirt into the river and pinning a few rails a-top.

However, local rail traffic continued over the "Black Canyon Line" until the route was finally abandoned in the early 1950s.

[19] Torrence, a Montrose native and an expert mountaineer, joined four other men in a failed expedition to explore the canyon in September 1900 using two wooden boats.

Torrence and Fellows opted to bring a small specially made multi-chambered rubber raft with a lifeline all the way around it instead of the wooden boats that had doomed the previous journey.

The two men entered the canyon on August 12 equipped with "hunting knives, two silk lifeline ropes, and rubber bags to encase their instruments."

Torrence and Fellows each had backpacks weighing 35 pounds and the rubber raft turned out to be a great way to float their gear on the narrow river.

After 10 days of climbing over rock falls, descending waterfalls, and swimming over 70 sections of the river, they emerged from their 30 mile run with a first recorded descent as well as a suitable tunnel site.

Working conditions at the tunnel were difficult due to the high levels of carbon dioxide, excessive temperatures, humidity, water, mud, shale, sand, and a fractured fault zone ....

In spite of good pay and fringe benefits, most disliked the dangerous underground conditions and stayed an average of only 2 weeks.

During 1933–35, the Civilian Conservation Corps built the North Rim Road to design by the National Park Service.

[32] Wildlife in this park include the pronghorn, black bear, coyote, muskrat, six species of lizard, cougar, raccoon, beaver, elk, river otter, bobcat, and mule deer.

At the south rim there is one campground for tent and RV camping, one loop of which has electrical hookups, and several hiking and nature trails.

The Gunnison River is designated as a Gold Medal Water from 200 yards downstream of Crystal Reservoir Dam to the North Fork.

[39] Downstream, in the Gunnison Gorge National Conservation Area, the river is somewhat easier to navigate, though still very remote and only for experienced runners, with rapids that are Class III - IV.