Black Canyon(Gunnison, Colorado)

Brittany Thorstensen

Beginning with the Precambrian Era, two billion years ago, the granite-like rock of gneiss and schist, also known to be a metamorphic rock, formed the core of this canyon.

http://tapestry.usgs.gov/ages/precambrian.jpg

Gneiss is a mineral that is coarse-grained and has distinct mineral layers. It is a metamorphic rock that is affected by heat and pressure. Schist is another metamorphic rock that is thin and has flaky layers of platy minerals.

http://upload.wikimedia.org/wikipedia/commons/4/4e/Augen-gneiss-2.jpg

Formation of Gneiss

The gneiss and schist that makes up the steep walls of the Black Canyon formed 1.7 billion by the collision of ancient volcanic island arcs. These arcs caused the surface of the metamorphic rocks that were exposed to extreme heat pressure.

http://pubs.usgs.gov/of/2000/ofr-00-0365/subzon.gif

http://static.bbc.co.uk/earthscience/images/ic/640x360/natural_disasters/volcano.jpg

After Pangaea broke up the continents were free to drift apart, eventually after millions of years the plates that the continents sit upon converged, (continental-continental convergence) causing an uplift of a region that results in large mountain ranges or plateau in the case of the Black Canyon.

http://img197.imageshack.us/img197/4343/pangea.jpg http://eas.unl.edu/~tfrank/History%20on%20the%20Rocks/Nebraska%20Geology/Cretaceous%20Webpage/Global%20Events/90moll.jpg

http://www.divediscover.whoi.edu/images/tectonics-collide.jpg

The Gunnison River dug down through the Precambrian gneiss and schist at the rate of 1-inch (25 mm) every 100 years. The extreme hardness of the

metamorphic rock along made it such as difficult task.

http://www.fodors.com/world/north-america/usa/colorado/black-canyon-of-the-gunnison-national-park/pic.jpg

http://3.bp.blogspot.com/-0IRWMVADQus/UEgVZpXY71I/AAAAAAAAAQQ/xzfBWINfHwA/s1600/Black+Canyon+016+(Large).JPG

http://venkateswara.org/viswavani/online-ruler-852.jpg

http://4.bp.blogspot.com/-gfUT8TC0v2Y/UEgVXP6WOaI/AAAAAAAAAQI/7mEn488Ric4/s1600/Black+Canyon+008+(Large).JPG

The uplifting process formed the Colorado Plateau 5 million years ago. This plateau stretches through parts of Colorado, New Mexico, Utah and Arizona. The plateau occupies 130,000 square miles.

http://pubs.usgs.gov/fs/fs-0145-99/fig1.jpg

http://4.bp.blogspot.com/_u8RzBC9dWv0/SLw3Bkj7YyI/AAAAAAAAAt4/K7jQ6eO6-sY/s400/Dsc00162+Vermillion+Cliffs+b.jpg

The rise of this plateau caused the rivers that run through this area to slowly erode creating a canyon. The Gunnison River began to run through the land, and down the slop of the plateau to form the Black Canyon.

http://www.nps.gov/blca/photosmultimedia/upload/blca_innercanyon01a.jpg

http://cdn.c.photoshelter.com/img-get/I0000vAF73HzvJwI/s/840/Black-Canyon-Gunnison-6038.jpg

Though to create the canyon it took over two million years because the minerals of Gneiss and Schist are very hard to erode away.

The flow of the Gunnison River through the Black Canyon though did not begin until after the ending of volcanic activity in the West Elk Mountains as

well as the San Juan Mountains.

http://www.cbc.ca/gfx/images/news/promos16x9image/2011/07/06/volcano-cp-00900761-460.jpg

http://farm5.static.flickr.com/4147/5026005786_334de962ae.jpg

http://www.dvorakexpeditions.com/wp-content/flgallery/images/8trgu7xm.jpg

Fluvial process, defined as running water (stream and rivers) is the unchanneled downward movement of surface water as well as water movement along the bottom of a valley.

http://www.ngu.no/upload/Klima%20og%20milj%C3%B8/Landskapsutvikling/Overflate.jpg

http://www.roadtripamerica.com/routes/2010/black_canyon_ericfoltz-590.jpg

The Black Canyon has been eroded away by the Gunnison river that flows through the bottom of the valley. The river breaks down the metamorphic rock and carries it downstream to be deposited elsewhere. Since the river is rather large erosion is greater than if it where just a stream.

The black canyon forms a V shape due to the river and its erosion.

http://3.bp.blogspot.com/-1b4loAL42Es/UEgVkmjPIEI/AAAAAAAAAQ4/VP6m-MQNPFw/s1600/Gateway+018+(Large).JPG

http://www.backpack-and-gear.com/image-files/black_canyon_of_the_gunnison_national_park.jpg

The stream cuts into the land because it is freely flowing down the slope of the canyon, thus it creates a v-shape rather than a U-shape left by a glacier.

Bibliography

• http://www.nature.nps.gov/water/Homepage/images/BLCA.jpg (Title Page)