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.
Links to the
papers:
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
NASA Photographs of
the Colorado River Basin
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
Animated Movies (with
classical music)
Southwest U. S. and North American Paleogeography
Maps by Ron Blakey - animation by Steve Perrin
http://www-personal.umich.edu/~sperrin/geology/paleogeography.html
Ancestral River
Systems of the World
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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