Grand canyongreenspun.com : LUSENET : Introductory Geology, Oswego State : One Thread
I have a quick question about how the grand canyon was formed. I know that wind and rain impacted the shape of it, but where did all those rocks come from in the first place?
-- Christi (firstname.lastname@example.org), March 28, 2001
I found the answer to your question about the Grand Canyon on the website: www.kaibab.org/geology/gc_geol.htm . The Earth's continents are on plates, which are not fixed in place, but float on a sea of molten rock. The Grand Canyon is located on the North American plate. This plate, used to have a much different climate than it does now because at one time it was located considerably further south. In time it has gradually moved north and rotated about ninety degrees to its present location and position.
The North American Plate is moving west and is colliding the Pacific Plate, which is moving towards the northwest. The Pacific Plate is also expanding from its middle and its eastern edge is being subducted beneath the North American Plate as it comes into contact with it. The collision between the plates is frequently responsible for mountain building activity. As the plates are forced together they sometimes buckle which causes mountain ranges to be formed.
The sediments that cover the mountains were deposited by a series of advancing and retreating ocean coastlines. As the climate of our planet warms and cools the sea level of the planet rises and falls due to the melting and freezing of the polar caps. When the sea level rises, land areas that are close to the coast and relatively low in altitude are sometimes submerged. This was the case with the land area of the Grand Canyon and is why so many different sedimentary rock layers exist.
-- Megan O'Rourke (email@example.com), March 28, 2001.
the norhtern plates and the what ever plate collided and caused a big hole and the water and wind wethered it down
-- harold menor (firstname.lastname@example.org), January 08, 2004.