Dean M. Chriss
Black Canyon of the Gunnison River, Painted Wall
(Click image to enlarge)
The Black Canyon of the Gunnison River is among the most inaccessible canyons in
the United States. The distance between its north and south rims is as small as
1,100 feet (335 meters), yet the striped "Painted Wall" shown in the photo above
is the tallest vertical wall in the state of Colorado with a height of 2,250
feet (686 meters). The name "Black Canyon" derives from the fact that the canyon
is so deep and narrow that parts of it receive only 33 minutes of sunlight per
day. Pleasing photographs are best taken on an uncommon overcast day, or during
twilight to avoid harsh shadows.
The Gunnison River drops at an average of 95 feet per mile through the
National Park. By comparison, the Colorado River drops an average of 7.5 feet
per mile through Grand Canyon National Park. In the most turbulent section the
Gunnison River drops 240 feet per mile (45 m/km).
The stripes in the
Painted Wall shown in the photograph above are granite-like igneous rock that formed as hot magma forced its
way into cracks. It cooled slowly, allowing large crystals of the pinkish
mineral potassium feldspar to form. It is also loaded
with shiny muscovite (mus'-ko-vite), which is also known as mica.