Over billions of years, the area that is now the Grand Canyon transformed from tall mountains to a flat plain and was later uplifted by tectonic activity. Around 12 million years ago, the Colorado River was dammed and formed a huge lake, Lake Bidahochi. Around 5.5 million years ago, the river reconnected in a new channel and began cutting through the plateau, forming the Grand Canyon over millions of years of erosion from water and weathering. The Grand Canyon continues changing today through ongoing erosion.

1. Origins and Shaping

2. (The Inquisitr, Online, accessed 28 Apr 2012)
The Grand Canyon
277 miles long
18 miles across at its widest
more than 1 mile deep

4.  Scientists have been studying the Grand
Canyon for years, trying to answer that very
question.
 They may be getting close.

5. 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.

6. 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.

7. 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.

8.  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.

9. 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.

10.  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.

11.  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)

12.  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.

13.  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

14.  (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.

15.  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:ANd9GcSf8YX1uqxpj2HACImeCyVQk1ryHA2NBXXLHlZ9Hv
q2duCWPkLF2sxh335T).
 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/imag
es/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.