What kind of erosion created the grand canyon

By looking at the type of sediments the deposits contain, scientists determine whether or not the rocks were deposited by the river. Rocks deposited by the river are younger than the river, as the river needed to be around to deposit them.

Rocks not deposited by the river are older than the river because the river was not yet there to drop them. When possible the scientists then date these rock deposits. The age of the river falls between the rocks determined to be older than the river and those determined to be younger. Through this method, scientists have estimated an age for the river, and thus the canyon through which it flows, of million years. Hualapai Limestone 6 - 11 million years ago.

The Hualapai Limestone was deposited in a warm, shallow freshwater lake just west of the Grand Wash Cliffs. It does not contain any river sediments, therefore, the Colorado River was not flowing yet when the Hualapai Limestone was deposited. The estimated age of the Hualapai Limestone is 6 million years. It was obtained from the Fortification Basalt, a lava flow that is interbedded with the sediments. Sandy Point Basalt 4. The river was therefore present and flowing before the basalt was deposited.

The Sandy Point Basalt is 4. The quartz-rich sands and silts of the Bouse Formation are found in just three basins along the modern Colorado River. Scientists believe that these sediments came from the Colorado River, though their precise depositional environment is debated. Some believe the Bouse Formation was deposited in an estuary, while others claim that deposition took place in a series of freshwater lakes fed by the Colorado.

The water in both of these possible environments would have been from the Colorado River. Therefore, the river was already flowing about 5 million years ago. Imperial Formation 4. The Imperial Formation is composed of both marine and deltaic sediments, meaning that it was deposited at the mouth of a river on a delta that was sometimes covered by the sea. Colorado River sediments are found in this formation. In particular, the Imperial Formation contains microfossils from rock layers on the Colorado Plateau.

The Colorado River, then, must have been carrying eroded rock materials from the Plateau to its mouth by 5 million years ago. It was this event that allowed for the establishment of the modern, through-flowing Colorado River.

Connecting the Colorado River of the Colorado Plateau with an outlet to the sea lowered the base level by about 5, feet 1, m. The base level is the lowest level to which a river can erode its bed. The ultimate base level is sea level 0 ft. The introduction of this lower base level created the conditions necessary for incision through the Colorado Plateau to occur.

How did the Colorado River and the canyon come to be? It is fairly easy to explain the formation of Grand Canyon through downcutting, weathering, and erosion. It is more difficult to explain just how the Colorado River came to be in its current location. We can think of the development of the Colorado River as a history book with many chapters. The most recent chapter is familiar, because it is the chapter that is visible today.

But, there are a number of chapters missing. The plotlines of some of those missing chapters are heavily debated. There are a few chapters in the story that the majority of geologists agree upon.

For one, evidence collected thus far suggests that the upper and lower reaches of the Colorado River are different ages. The lower section in California, Nevada, and Arizona is younger than the upper portion in Utah and Colorado. The age of the younger portion of the river is estimated to be between 5 and 6 million years based on the various constraints listed in the Ages section.

When the upper and lower portions combined, an event called drainage integration, the Colorado River became what it is today. In other words, the river that we know today as the Colorado River, was actually once either two different rivers that have been joined together or a much shorter river that was later lengthened. We know younger rocks once rested on top of the Kaibab Limestone because of land forms such as Red Butte south of Grand Canyon, which is composed of some of these younger rock layers.

The majority of these rock layers, however, have been eroded away. We can only guess what the landscape might have looked like, but it is likely that this unknown topography influenced the present course of the river. Today, the Kaibab Plateau, a high point through which the river gingerly slices, poses a problem for geologists. It may have been smaller 10 to 30 million years ago, or perhaps it was buried beneath layers of flat-lying Mesozoic rocks, only to be revealed after the river had already established its course.

As we learn more, some hypotheses may be confirmed or proven false. There is still much to be learned about the Colorado River and Grand Canyon. As more research is completed, we will continue to learn. The Little Colorado River Hypothesis. In attempting to address the age differences between the upper and lower reaches of the Colorado River, Edwin McKee suggested that the Colorado River in Grand Canyon formed when two different rivers met.

The young Colorado River would have slowly worked its way back from the Gulf of California by headward erosion, to eventually capture the ancestral Colorado River and form the river as we know it today.

In order for this theory to work, the ancestral Colorado River would have needed to flow eastward over the continental divide. There is however no evidence in the Little Colorado River drainage system to support the idea of an eastward flowing river. The Northwest Flowing River Hypothesis.

Geologist Ivo Lucchitta and others believe that the ancestral Colorado River crossed the Kaibab Plateau as it does today and then veered off to the northwest alongside a ridge.

Like McKee before him, Ivo Lucchitta then suggests that the young Colorado River captured the ancestral portion by headward erosion to create the modern through-flowing river. Unfortunately, no sedimentary deposits have been found to support this theory.

A few geologists have hypothesized that the ancestral Colorado River was temporarily dammed behind the Kaibab Plateau and other high points. Just as water pools and collects behind Glen Canyon Dam to form Lake Powell today, the water from the ancestral Colorado River would have pooled and collected behind multiple high points, forming a chain of ancient lakes, one of which has been dubbed Lake Bidahochi. Sediments believed to have been deposited by these ancient lakes have been found in Arizona.

According to the hypothesis, the lakes would have remained until a the young Colorado River cut through the Kaibab Plateau and other high points by way of headward erosion, creating an outlet to the sea, or b the lake overflowed the plateaus, rapidly carving the canyon, and connected with the young Colorado River on the other side. Collapse of a Groundwater Karst System. This is a very new idea and it is still being developed. Hill proposes that precipitation falling on the Colorado Plateau drained into the Redwall aquifer karst through features such as sinkholes, cracks and joints.

The water in the Redwall aquifer then flowed through the Kaibab Uplift to connect with the headward-eroding young Colorado River in western Grand Canyon. Hill proposes that collapse and incision of the canyon then followed along this already weakened subterranean route. Last updated: October 17, Stay Connected. Subduction Scientists have observed that the angle of subduction directly affects the landscape on the South American continent.

Water-carved Canyons Grand Canyon is perhaps the best example of a water-carved canyon. Glacial Valleys Glaciers can change large areas of land by abrasion, a scraping action, and plucking, a lifting action. Rift Valleys A rift valley is created when two plates of Earth's crust pull apart.

The Colorado River flows through an Arid Climate Mechanical weathering happens relatively quickly in arid regions. Volcanism Much of Northern Arizona is dotted with cinder cones, lava domes and stratovolcanoes. Faulting Numerous normal faults cut across Grand Canyon.

Hualapai Limestone 6 - 11 million years ago The Hualapai Limestone was deposited in a warm, shallow freshwater lake just west of the Grand Wash Cliffs. The Northwest Flowing River Hypothesis Geologist Ivo Lucchitta and others believe that the ancestral Colorado River crossed the Kaibab Plateau as it does today and then veered off to the northwest alongside a ridge.

Spillover Theory - the Catastrophic Draining of Ancient Lakes A few geologists have hypothesized that the ancestral Colorado River was temporarily dammed behind the Kaibab Plateau and other high points.

Echoes of our exhilarated yells bounced from the walls and back to our ears as the sun began to set in the west, lighting up the red and white of the walls. March 14, The hike down took about an hour and a half, with a few stops along the way for educational purposes… mainly to look at fossils, differentiate between the strata, and view the trackways of the Coconino.

A few people stopped at the end of the Coconino Sandstone and headed back up, unwilling to hike down any further and face an even longer climb to the top. The rest of us continued, some stopping at the Hermit Shale and others towards the end of the Supai Group. Lunch in the Hermit Shale was pleasant. We ate lunch consisting mostly of deli meat sandwiches, pickles, and jumbo bags of beef jerky beneath a shade tree and tried not to sit on cactuses.

We stopped at every other switchback, shouting obscenities about the large steps in the Kaibab and Coconino. Once we reached the top, it was one of the best feelings in the world. Beus, S. Blakey, R. Condon, S. Geological Survey Bulletin P. Karlstrom, K. Lockley, M. Columbia University Press, New York. Lull, R. McKee, E. Middleton, L.

Skip to content — Skip to search. The University of Rhode Island. Email eCampus Brightspace Handshake. However, they are not nearly as large, nor can they replicate the conditions of its formation borrowed from Ranney, : Thick stack of stratified rock.

Varied and vivid color within the strata. Widespread, gentle uplift such that the strata remain relatively flat-lying. The presence of large rivers and their tributaries. A modern arid climate. The Grand Canyon is carved into a series of flat, seemingly uninspiring plateaus. It averages ten miles across and one mile deep.

The estimated material eroded from the Canyon is approximately one thousand cubic miles. Tectonic uplift of the Colorado Plateau and resultant erosion from the Colorado River, along with additional weathering due to freeze-thaw processes, has carved the Grand Canyon to the extent we see today Karlstrom et al.

Wind has removed sediment and other materials from the canyon walls, assisting in widening the canyon to its current width. The absolute age of the canyon is unknown and is a subject of great debate among scientists. For many years, the canyon was thought to be five to six million years old — very young in geologic time.

The canyon itself has formed much more recently than the deposition of rock layers, only about five million years ago as opposed to the rocks, the youngest of which are a little less than million years old. The canyon has since been forming at varying rates, with periods of intense erosion carving the canyon. The river must have had periods of quick movement, carving deep, not only wide.

To view or download a report about the Colorado River downstream of Grand Canyon, click here. The river continues to be an agent of change, reshaping the canyon over time. There is ongoing research about river flow, sediments, and geomorphology. The Glen Canyon Dam controls the Colorado River now, providing electricity to six states and changing the natural flow patterns. Since the construction of the dam in , researchers have been studying how changes in river flow affect the erosion and deposition of sediment along the Colorado River and the changes to riparian vegetation and food webs.

The Paleozoic Strata contain many fossils that help scientists learn about the geologic history of North America. Most of the fossils are ocean-dwelling creatures, telling us that the area now in the middle of Arizona was once a sea. Some of the most common fossils found in the Grand Canyon are listed below. Trilobites were invertebrates that lived in shallow marine environments and varied widely in size.

They are index fossils for the Paleozoic, and were particularly prominent during the Ordovician. Tracks and burrows are known as trace fossils, because they are not preservations of the actual organism, but instead show where the organism moved and lived. They are commonly tunnels dug by trilobites and worms in muddy ocean sediment. Public domain.

The North Rim of the Grand Canyon, showing a tree growing on a ledge overlooking the canyon. Visualization of map of riverbed and canyon walls near Navajo Bridge, 4. River bathymetry was measured with multibeam sonar and topography was measured with a boat-mounted laser scanner. The data from this survey collected in April will be used to measure changes in sand storage on the river bed and to model streamflow and sand transport.

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