THE GRAND CANYON Origins and Shaping

The Grand Canyon

(The Inquisitr, Online, accessed 28 Apr 2012)

277 miles long 18 miles across at its widest more than 1 mile deep

How did it get there?

Scientists have been studying the Grand Canyon for years, trying to answer that very question.

They may be getting close.

Fresno Pacific University, online, accessed 28 April 2012

2 billion years ago, this area of Arizona was covered with mountains. Some of the peaks reached 6 miles in height.

Royal Belgian Institute of Natural Science, online, accessed 28 Apr, 2012

Over the next 500 million years, through the action of ice, water and wind, the mountains gradually eroded away.

What was left was a flat, featureless plain.

Share, Dr. Jack, online, accessed 27 Apr 2012

Then, between 70 and 50 million years ago, the Farralon Plate shallowly subducted under the North American Plate.

This was known as the Laramide Orogeny and resulted in the uplifting of the Colorado Plateau, as well as the growth of the Sierra Nevadas and the Rocky Mountains to the west and east of it.

The Rocky Mountains were steep. With snow runoff and rain, all of that water needed somewhere to go. Gradually, the Colorado River was born.

The Colorado River flowed south, down to drain into the Gulf of Mexico. About 12 million years ago, the path of the river became blocked. This caused all the waters of the river to drain into a basin and form a tremendous lake, Lake Bidahochi. (Ribokas, Bob, online, accessed 29 April 2012)

Lake Bidahochi was located about 100 miles east of the modern day site of the Grand Canyon. The lake contained about 3,000 cubic miles of water, making it larger than Lake Michigan.

Ribokas, Bob, online ,accessed 29 April 2012

Meanwhile, the Hualapai Drainage System, which was cut off from the original route of the Colorado, began working its way around the Kaibab plateau, towards the huge lake.

Eventually, about 5.5 million years ago, the drainage system reconnected with the Colorado River.

The newly connected channel allowed the lake to empty to the west.

It is theorized that the rushing of that great mass of water is what started the downcutting of the gorge that became the Grand Canyon of today.

Blog KSMQ, online, accessed 30 Apr 2012

A river in flood can dislodge and move great amounts of sediment, all the way from tiny particles of silt to blocks of rock as large as a house.

The Colorado River today is known to transport 5 tons of sediment every second, or 300 tons every hour. This is enough to fill 100 Olympic-sized swimming pools. (The History Channel,

Netflix online, accessed 24 April 2012)

By testing of ancient sand deposits near the start of the canyon, at Lee’s Ferry, Dr. Karl Karlstrom, University of New Mexico was able to determine that the rate of downcutting of the Grand Canyon was about 1 inch per century. (The

History Channel, Netflix online, accessed 24 April 2012)

Since the canyon is about 5300 feet deep, this means that the Grand Canyon formed as it is today in just over 5 million years.

The Grand Canyon is not finished. Everyday, the material lining the walls of the canyon is subjected to weathering and erosion through the action of ice, water and gravity.

RocScience, online, accessed 30 April 2012

(Royal Belgian Institute of Natural Science, online, accessed 28 Apr, 2012)

Millions of years in the future, the Earth’s search for equilibrium will have flattened the Grand Canyon to a river and another flat plain, like the Mississippi.

Bibliography Author Unknown, The Inquisitr, Grand Canyon Plane Crash Leaves Two Dead, (

http://www.inquisitr.com/wp-content/2011/08/grand-canyon-plane-crash-2011.jpg ) 1 August 2011.

Author Unknown, Fresno Pacific University, Teacher Guide-Geography Lesson #41 (http://t0.gstatic.com/images?q=tbn:ANd9GcSf8YX1uqxpj2HACImeCyVQk1ryHA2NBXXLHlZ9Hvq2duCWPkLF2sxh335T).

6: Royal Belgian Institute of Natural Science, IUAP Project – The Land of Summer and Akkad, (http://www.naturalsciences.be/institute/structure/geology/gsb_website/research/archives/images/recherche/sedimento/flatness.jpg).

7: Share, Dr. Jack, Written in Stone…seen through my lens, (http://1.bp.blogspot.com/-J2oEQPJQcVc/TlDdBjXBXdI/AAAAAAAAAc0/R9gVPko1Ct4/s1600/Farallon+subduction.jpg ), 1 September 2011.

8: Ribokas, Bob, Grand Canyon Explorer, The Formation of the Grand Canyon, (http://www.bobspixels.com/kaibab.org/geology/canform.htm ).

11: Blog KSMQ, Relief for flood victims, (http://blog.ksmq.org/wp-content/uploads/2010/09/FLOOD-1-STILL.jpg ), 25 September 2010.

11: The History Channel, How the Earth Was Made, Season 2 Episode 1, 2010.

14: RocScience, Statistical Analysis of Rockfalls, (http://www.rocscience.com/assets/files/uploads/7901.jpg ), 2012.