The Grand Canyon A water created landform. The WOW Factor.
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Transcript of The Grand Canyon A water created landform. The WOW Factor.
![Page 1: The Grand Canyon A water created landform. The WOW Factor.](https://reader030.fdocuments.us/reader030/viewer/2022032723/56649d055503460f949d8907/html5/thumbnails/1.jpg)
The Grand Canyon
A water created landform
![Page 2: The Grand Canyon A water created landform. The WOW Factor.](https://reader030.fdocuments.us/reader030/viewer/2022032723/56649d055503460f949d8907/html5/thumbnails/2.jpg)
The WOW Factor
![Page 3: The Grand Canyon A water created landform. The WOW Factor.](https://reader030.fdocuments.us/reader030/viewer/2022032723/56649d055503460f949d8907/html5/thumbnails/3.jpg)
Why is the Canyon Grand?
• The River rises at 5,000m and so has great potential energy
• The Colorado Plateau has risen 3,000 m in the last 5 million years lifting the river above its base level
• The sedimentary rocks are easily eroded• The discharge is variable and at times very high• The local climate is very arid reducing vegetation
and available moisture
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The v shaped valley• Vertical erosion depends on
– The height above base level– The resistance of the rock– The energy of the stream
• Slope erosion depends on– The moisture available– The resistance of the rock– Permeability of the rock
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The oldest, most resistant rocks produce the steepest valley sides
Less resistant rocks like shale give gentle slopes
Taken from Landmark AS Geography Prosser, Raw and Bishop, Published by Collins
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Limestone – permeable, resistant,
Shale – impermeable, easily weathered,
Coconino sandstone – very resistant,
Mixed sandstones and shales- some more resistant than others
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The Side Valleys
• Faults such as Bright Angel are easily exploited by water
• The gradient of side valleys is very steep
• Occasional rainstorms cause sheet-wash and free sediment
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Bright Angel Fault is a point of weakness
Redwall Limestone
Shale
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Study the Cross-section through the canyon
a. Describe the shape of the canyonb. Look at the exposures of limestone on the valley sides. Do they produce steep cliffs or gentle slopes?c. What rock type consistently produces relatively gentle
slopes on the valley sides?d. Most of the beds of rock are horizontal. Do you think this has affected the profile in any way?e. Why do you think the valley at the base of the Canyon is
narrower than the canyon higher up?f. How has the climate of the area encouraged the formation of the canyon?