There are two stories regarding Grand Canyon geology. Part one concerns the actual rock layers, and in particular, when and how they were deposited. This subject has been covered in depth in many other papers. Part two of Grand Canyon geology deals with why the Colorado River happened to pick this particular path allowing it to cut the Grand Canyon.

   This research paper is an attempt to depict the geologic history of the Colorado River, and in particular, how it formed the Grand Canyon. The time period starts with the late Cretaceous and continues through the Tertiary to the "Grand Canyon Event" in the late Miocene. As far as I know, no one else has presented such a model. Since the model is the first of its kind, it should be regarded as a "trial theory" as opposed to generally accepted knowledge. As such it will be subject to future "refinements". Any additional knowledge that other observers may have would thus be appreciated.

   Some of the feedback that I have received disagrees with the conclusions that I have presented in the model. Readers should understand that better models may exist or may be developed. My policy will be to update the model if there is evidence indicating there is a minor problem, or pull the model entirely if there is evidence that can not be resolved. In either case I will pay attention to other conclusions, but evidence must be provided if it involves changing anything.

Photo courtesy of NASA.
Wyoming is at the top right. Utah and the salt deserts are in the upper left – stretching to the Gulf of California in the lower left.

   The linchpin to much of the scenery in the southwestern U.S. as well as the most dramatic event in the river's geologic history is the origin and formation of the Grand Canyon. The only way to appreciate the Grand Canyon’s size is to visit it.

   One of the ways to see the Grand Canyon is to take a raft trip through it. The most dangerous part of such a trip is that it becomes expensively addictive, leading to future trips.
 
   Only when you raft some of the big rapids do you comprehend the power of the river, and this is just a sample of the power that was here before Glen Canyon Dam held back spring runoffs pouring down from the high Rockies.

Power sufficient to move mountains.
How many mountains?
The answer is - All of them.


March 7, 2008 update:
Recent newspaper reports have suggested that the Colorado River began to cut the Grand Canyon 17 million years ago.
These reports are in error!
   A research study conducted at Grand Canyon Caverns came up with the 17 million years ago date which is valid at that location, but Grand Canyon Caverns is in a different drainage system which is controlled by displacement along the Grand Wash Cliffs/Fault to the southwest of Peach Springs, AZ. The attempt to extend the Grand Canyon Caverns observation to include drainage of the Colorado River in the Grand Canyon is not valid.

   Multiple research studies support the model presented here that local erosion in the western Grand Canyon was beginning about 17 million years ago, but a through-flowing Colorado River to the Pacific Ocean did not exist until about 5.4 million years ago. Within this 5.4 million years ago to present timetable, most of the downward cutting has been concentrated in the last 2.5 million years.





 
 
Evolution of the Colorado River and its Tributaries

Appendix to the Evolution of the Colorado River

Cenozoic River Maps (Suggest you print this. Please allow a few seconds to download.)

Image Index  Intro to many different pages - each with computer generated 3-D Pictures/Images, and a short narrative.

Also please see



View area extends from the Gulf of California to central Wyoming
Photographs taken June 6, 2001

Low Resolution (1125w x 1450h) - 326 KB
http://visibleearth.nasa.gov/images/1980/FourCorners.A2001162.1815.1km.jpg

Medium Resolution (2250w x 2900h) - 1.52 MB
http://visibleearth.nasa.gov/images/1980/FourCorners.A2001162.1815.500m.jpg

High resolution (4500w x 5800h) - 4.43 MB
http://visibleearth.nasa.gov/images/1980/FourCorners.A2001162.1815.250m.jpg




Southwest U. S. and North American Paleogeography
Maps by Ron Blakey - animation by Steve Perrin
http://www-personal.umich.edu/~sperrin/geology/paleogeography.html




Also, please see “Ancestral River Systems of the World ”
A pictorial world tour of river systems that flow through mountain ranges instead of going around them - and why they do it.






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