Future Changes at The Grand Canyon

The story of the Grand Canyon began 30 to 70 million years ago when plate tectonics led to the uplift of the Colorado Plateau. This uplift left a high and flat rock formation that allowed the Colorado River to carve downward beginning 5 to 6 million years ago. As the river began to carve out the canyon, the processes of weathering and erosion came along contributing to the 18 mile wide, one mile deep canyon. Looking into the future for the canyon, downcutting, erosion, weathering, and faulting will continue to have the largest impact on the landscape and will cause widening and deepening of the canyon.

Within the next 1,000 to 10,000 years, the canyon will look much as it does today because carving out noticeable changes is too lengthy a process to see anything considerable within the time frame. Nevertheless, the appearance of the canyon will change because downcutting by the river, weathering and erosion will continue to expose new rock. The process of mass wasting will lead to most of the carried off rock particles, but weathering in different forms will lead to erosion as well. At the canyon, mass wasting can be seen in the form of falls and flows. Falls occur when rocks become detached usually because of a steep slope or undercutting.  Undercutting occurs when the bottom portion of a rock is eroded to the point where the top of the rock becomes too heavy to stand and eventually detaches and falls off.  

The canyon pictures provide examples of mass wasting in the form of falls and talus (rock particles) that accumulate. An example of undercutting is also displayed.

 

Mass wasting in the form of mud and debris flows occurs at the canyon especially during times of thunderstorms that produce flooding. The Colorado River runs 277 miles long across the canyon and descends 2,000 feet in elevation. This steep slope contributes to the river's speed allowing it to carry lots of debris including large boulders. 

This YouTube video beautifually captures an actual debris flow. Towards the middle of the 4 minute clip you see a highly thixotropic consistency in the flow.  http://youtu.be/TDtBby7lJX0

 

In the time span of one million years, faulting will have also lead to a detectable widening of the canyon. Currently, there are numerous normal faults at the Grand Canyon. These faults are created as landforms are being pulled apart from one another. The most active faults at the canyon have moved vertically between 520 and 720 feet in the past 2 million years. Uniformitarianism claims that the geological processes that have occurred in the past will occur again, therefore, in one million years the canyon should have spread by faulting a maximum of 360 feet.

This picture is of a very prominent fault at the Grand Canyon.

With a landform as massive as the Grand Canyon, one thousand to ten thousand years is too short a period of time to see prominent geological changes. Downcutting, weathering, and erosion occur constantly at the canyon, but the enormity of the canyon hides such small changes in a seamless manner. One million years would be just enough time for all of these minute changes to accumulate into measurable changes. The depth and width of the canyon make it difficult to hypothesize that anything other than widening would occur to this canyon.

Sources

 

http://www.nature.nps.gov/views/layouts/Main.html#/GRCA/geology/

http://clasfaculty.ucdenver.edu/callen/1202/Battle/Destroy/MassWasting/MassWasting.htm

http://clasfaculty.ucdenver.edu/callen/1202/Battle/Build/Faulting/Faulting.html

http://www.bing.com/images/search?q=fault+lines+at+the+grand+canyon&view=detail&id=44487471E3661F74843118675E01EEE5BC5AE506&first=38

http://www.bing.com/images/search?q=falls+and+undercutting+at+the+grand+canyon&view=detail&id=814D1BE9F0A626E84D788E92C7791EC4A7008834

http://www.bing.com/images/search?q=falls+and+undercutting+at+the+grand+canyon&view=detail&id=24783D4C03CE31649055D091645AA714625F95C1&first=30

http://www.bing.com/images/search?q=rock+falls+at+the+grand+canyon&view=detail&id=A2B9C25FFBA1AC36C5CC10191C23B85DA46E0A6C