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







 

Weather at the Grand Canyon

Weather at the Grand Canyon varies greatly. The four seasons bring an array of conditions depending on your location. The driest conditions and lowest humidity exist during late spring and early summer. Winter and fall bring heavy rain, thunderstorms, and harsh snow storms as seen in the following pictures.

http://www.bing.com/images/search?q=rain+at+the+grand+canyon&view=detail&id=58574A7D0ED9C88EC39A207A3AB22CCC914DFDF7



 http://www.bing.com/images/search?q=thunderstorms+at+the+grand+canyon&view=detail&id=7AC3645052D9A0BDD5D7C31585EAA6B3BEB6E05D

 

 

 http://www.bing.com/images/search?q=snowfall+at+the+grand+canyon&view=detail&id=645F910CAE493C543F4699CD42DA6A70309DFD3F

The North Rim of the canyon has experienced temperatures of -22 °F, while the south Rim of the canyon has experienced 120°F on several occasions. Along with temperature, precipitation around the canyon varies widely. The North Rim of the canyon averages 25.8” of rain a year, while the South Rim has areas that receive less than 1” of moisture a year. Precipitation depends on cloud formation and the production of rain through a series of atmospheric conditions and adiabatic processes.  These processes along with the wide range of precipitation occur because air masses in the atmosphere exist under different conditions. Air masses exist as stable, unstable, or in between in conditional stability.

http://www.paragonair.com/public/docs/AdvCircs/AC00-06A_AvWx/AC00-6A_ch06.html

Notice in this picture, the stable air mass is resisting vertical movement, while the unstable air is rising. Unstable air will rise in the presence and subsequent removal of force. Conditional stability happens when the air mass is neither stable nor unstable. This air mass will behave stable, but can change to unstable when force is applied.

 

 

Air masses rise when warm, but begin to descend once cool. The high temperatures found at the canyon allow for warm air parcels to exist and rise. Depending on the condition of the air mass itself, the air parcels may rise leading to changes in temperature and cloud formation. 

 

 

In this picture, the red denotes warm air. Notice how the warm air rises. If the Dew Point (100%relative humidity ) is reached, clouds begin to form and can return what once left as warm air and water vapor, as moisture and cool air back to the ground. http://www.vivoscuola.it/us/rsigpp3202/umidita/lezioni/form.htm

 

 

 

http://www.britannica.com/EBchecked/media/140263/Condensation-precipitation-and-the-rain-shadow-effect-resulting-from-orographic

The above picture depicts orographic lifting and the rainshadow effect. In the above picture, the air mass encounters a barrier that pushes the air upward along what is called the windward side. The air is moved high enough for condensation to occur bringing about precipitation. As the air begins to descend onto the leeward side of the mountain, all the precipitation has been left behind on the windward side. This leaves nothing but dry warm descending air. This process creates the driest of the areas around the canyon as shown in the following picture.

http://clasfaculty.ucdenver.educallen/1202/Climate/Weather/GrdCynAdiabaticWarming.jpg/

Sources

http://www.nps.gov/grca/planyourvisit/weather-condition.htm

 http://www.nps.gov/grca/naturescience/weather.htm

http://blackboard.cuonline.edu/webapps/portal/frameset.jsp?tab_tab_group_id=_2_1&url=%2Fwebapps%2Fblackboard%2Fexecute%2Flauncher%3Ftype%3DCourse%26id%3D_70686848_1%26url%3D

 

Faulting and Folding

A simple glance at the Grand Canyon is enough to know that forces have acted upon the rock formation to transform the canyon into the shape we see today. Two of these contributing forces are faulting and folding, and both occur as the earth’s crust is strained. Faulting occurs when the stress on a landscape is so great the landscape responds by breaking, creating a fracture on the surface. As opposed to earthquakes which are experienced as faults occur, the fault itself is the physical evidence left behind. Faults are caused by stress in the form of compression, extension, and side-by-side movement. Compression creates thrust faults, extension creates normal faults, and side by side motion creates strike-slip faults.

http://media.tiscali.co.uk/images/feeds/hutchinson/ency/c00948.jpg
 

According to the National Park Service, faults can be seen in most of the canyon’s rock layers. The movement measures from 15 to 16000 feet. One of the most famous faults at the Grand Canyon is Bright Angel Fault. Bright Angel Fault began as a normal fault 1700 million years ago, but has been reactivated twice since that time as a thrust fault, then again as a normal fault.  




http://farm9.staticflickr.com/8426/7805082778_40e0fbc395_z.jpg



http://www.wvgs.wvnet.edu/www/geoeduc/SedimentaryRocks/CSR09.jpg

Folding occurs when the stress on the landscape is not enough to cause it to snap, but enough to deform it or bend the landscape. Synclines are distinguished by their downward fold, anticlines through their dome like upfolds, and monoclines by a single slight bend.

 

At the Grand Canyon, most of the folds are monoclines. One of the most distinguishable folds is known as the East Kaibab monocline. I remember looking out of the observatory station of the Desert Watchtower, but little did I know I had the best view of the East Kaibab monocline. I plan on visiting the Grand Canyon again, and next time I will know whether I’m staring at a fault or fold.

 

 

 

 

Sources

http://www.physci.mc.maricopa.edu/Geology/FieldTrips/GrandCanyon/GrandCanyon_2004_Fall/GrandCanyon_2004_Fall_Images_640/DSC04383.JPG

http://www.nps.gov/grca/naturescience/upload/2-Grand-Canyon-Geology6-2009.pdf

http://www.physicalgeography.net/fundamentals/10l.html

http://www.nps.gov/grca/naturescience/faults.htm



Plate Tectonics

Although millions of years and a variety of processes have led to today’s view of the Grand Canyon, the process which gave way to its formation is known as plate tectonics.  Before discussing the specifics of plate movements, it is important to give credit to one of the contributors to the plate tectonic theory, Alfred Wegener. Alfred proposed the concept of “continental drift.” He believed at one point, “all continents were one huge super continent” known as Pangea. During his time, there was not enough evidence to convince skeptics, but since his death and the advanced understanding of earth’s structure, his idea is accredited within the paradigm of plate tectonics.

The plates responsible for continental movement are found in the lithosphere, the upper layer of earth’s structure. These plates are thought to float on top of the asthenosphere, a layer capable of movement because of its “plasticity.” The moving plates can be either continental or oceanic crust. Plate movement is classified in one of three categories. Divergence, which pulls plates apart, convergence, the coming together of plates, and transform, the process by which plates move side by side.

 

By understanding the type of movements made by earth’s plates, it is possible to imagine the convergence of the Pacific Plate (ocean crust) and the North American plate (continental crust) that led the way to the forming of the Grand Canyon. Millions of years ago when these two plates collided, the oceanic crust was subducted, meaning it was forced underneath the continental crust and this upward push of continental crust led to the Rocky Mountains as well as the uplift of the Colorado Plateau. The uplift of the Colorado Plateau allowed the Colorado River “to carve its way downward” about 5 to 6 million years ago commencing the creation of the canyon.

 

Sources

 







http://www.bobspixels.com/kaibab.org/geology/gc_geol.htm

http://nature.nps.gov/views/layouts/Main.html#/GRCA/geo/origins/
 
http://clasfaculty.ucdenver.edu/callen/1202/Battle/Build/PlateTectonics/PlateTectonics.html

http://tectonicplates.blinkweb.com/uploads.00139042/00142236.jpg

Grand Canyon

Hi everyone! My name is Carolina Gomez and I am a first year student at the University of Colorado Denver. I am an undergrad student seeking to major in Psychology. I have no children and no pets, but I do have a husband who I would at times like to categorize as a child. I can say that about him because we’re married and because he knows that I make fun of only those that I love. Outside of psychology, I enjoy many things.  Two of my most favorite things to do on earth, besides read (yes I’m a nerd) is travel, and spend time with the people I love. As I thought about a geographical location to explore, I decided that making the location personal would only encourage my research and so I chose the Grand Canyon National Park in Arizona. A few years back I took a road trip from Denver to Sedona, Arizona with one of my greatest friends. While there, we of course could not pass on the opportunity to go out and see the amazing and humbling landscape that is the Grand Canyon.

I used the word humbling to describe the Grand Canyon because that is exactly how I felt as I stood in awe and wonder staring into the vastness of the canyon. I felt smaller than an ant as I tried to take in the canyon’s enormity. I was also fascinated by the history of the Grand Canyon. Clearly this geological feature didn’t spring up overnight, and the processes that lead to its current formation is what I hope to explore as I undertake my first ever blogging experience. Hope you all enjoy learning about the Grand Canyon with me.