UCSB Science Line
Sponge Spicules Nerve Cells Galaxy Abalone Shell Nickel Succinate X-ray Lens Lupine
UCSB Science Line
Home
How it Works
Ask a Question
Search Topics
Webcasts
Our Scientists
Science Links
Contact Information
What are some constructive and destructive forces of the Colorado plateau and grand canyon?
Question Date: 2018-04-18
Answer 1:

The two mechanisms at work to construct the Colorado Plateau and the Grand Canyon are uplift (constructive), and erosion (destructive). Its geologic history begins ~140 million years ago, during the Cretaceous period; at that time the Colorado Plateau was simply sediments being deposited in an inland sea. These sediments accumulated for most of the Cretaceous, until ~70 million years ago (just 5 million years before the dinosaurs go extinct), when tectonic activity starts to occur. For the next 30 million years, the Colorado Plateau is uplifted (along with a good-sized chunk of the western US) during the Laramide orogeny (orogeny = mountain-building event), which created the Rocky Mountains. Uplift of the Plateau stopped ~40 million years ago, ending the constructive phase of the Colorado Plateau's geologic history. Since then, erosional forces (wind, water, etc.) have been working on the rocks, but the primary destructive force at work in this case is water (the Colorado River, specifically).

I hope that this answers your question. Have a great day!


Answer 2:

I'm not sure you can really describe these forces as constructive and destructive. There is geologic uplift that is shoving the rocks up, and then there is a river that is eroding the layers and creating these canyons. The layers of rock were deposited over eons of different conditions, but the whole area has been eroding for some time now. The youngest rocks in the Colorado Plateau are of Eocene (about 44 million years old) age.


Answer 3:

Topography, the height of the Earth's surface in comparison with the sea, depends on two factors: whether the bedrock is moving up or down and whether the rocks at the surface are being lost or added to. One good example of the first factor is the reason the Colorado Plateau is rising; our studies of the behavior of the plateau show a signal similar to hot rock moving upwards. The rising hot rocks can push up the plateau.

A similar force in the opposite direction would have happened more during the last ice age when larger glaciers in the mountain ranges on the Plateau were forcing the topography down, a bit like having a weight on a boat. The weight of the ice wasn't enough to overcome the forces that caused the plateau to rise.

What happens to rocks themselves is more important for shaping the Grand Canyon. The destructive forces of erosion from the Colorado River wash away bits of rock, called sediment, to the Gulf of California. This force helped shape the canyon, but other forces such as plants breaking rocks apart, wind carrying sand in or away, or freezing ice popping open cracks in stones all play their part in shaping the Grand Canyon and Colorado Plateau. But rocks don't just have to be carried away. Magma can build up the topography, either by erupting as lava and forming a volcano or solidifying underground.

Answer 4:

I found this interesting site:
geology

Part of the information there which will be interesting for you is:
"The most powerful force to have an impact on the Grand Canyon is erosion, primarily by water (and ice) and second by wind. Other forces that contributed to the Canyon's formation are the course of the Colorado River itself, vulcanism, continental drift and slight variations in the earths orbit which in turn causes variations in seasons and climate.

At around 17 million years ago, while the river was flowing across this ancient landscape, the land mass know as today's Colorado Plateau began to uplift. The uplift was caused by pressures deep with the Earth and may have been caused by additional conflict between the North American Plates and the Pacific Plates. This process continued until around 5 million years ago which interestingly enough is the date of the sedimentary layers just west of the plateau. At its greatest height the Colorado Plateau was once about three miles above sea level. The rise of the plateau probably prevented the seas from submerging it again and instead the topmost layers were eroded away and carried into the sea. The most favorable currently accepted theory is that the Colorado River continued to cut through the Colorado Plateau while the land rose around it. "



Click Here to return to the search form.

University of California, Santa Barbara Materials Research Laboratory National Science Foundation
This program is co-sponsored by the National Science Foundation and UCSB School-University Partnerships
Copyright © 2017 The Regents of the University of California,
All Rights Reserved.
UCSB Terms of Use