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
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.
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.
The Geological Society of America
2005 Salt Lake City Annual Meeting (October 16–19, 2005) Salt Lake City, Utahhttp://gsa.confex.com/gsa/2005AM/finalprogram/index.html
MIOCENE ARRIVAL OF COLORADO RIVER SAND IN THE SALTON TROUGH, SOUTHERN
CALIFORNIA: IMPLICATIONS FOR INITIATION OF THE LOWER COLORADO RIVER
DRAINAGE”http://gsa.confex.com/gsa/2005AM/finalprogram/abstract_91054.htm“Using this rate, the base of CR sand is dated at 5.36 ± 0.06 Ma.
Because the CR arrived in the Lake Mead area shortly after 5.51 Ma
(House et al., this volume), we conclude that the river propagated ~400
km to the Salton Trough in ~100-200 k.y. The rapid pace of drainage
integration supports a lake-overflow model, but does not rule out a
marine-estuary interpretation for basal limestone of the Bouse Fm.”
Note: The Wikipedia article about the Grand Canyon ( http://en.wikipedia.org/wiki/Grand_Canyon
) implies that the Colorado River started cutting the Grand Canyon some
17 million years ago. The Wikipedia article was based on an article in
the New York Times, but the New York Times reporter confused 17
million-year-old local drainage at the western end of the present Grand
Canyon with the Colorado River. The Colorado River didn’t arrive at the
present Grand Canyon until about 5.4 (+/-0.1) million years ago.
Nov. 29, 2012 Update
Multiple newspaper stories are reporting that 60 to 70 million
years ago western portions of the Grand Canyon were eroded down to
within a few hundred meters of current levels by a river system that
flowed from west to east through the Grand Canyon. The reference source
for these newspaper reports is an article by Rebecca M. Flowers and
Kenneth A. Farley in the current issue of Science
Erosion down to this level 60 million years ago by an
eastward flowing river through the present Grand Canyon would be IMPOSSIBLE !!! since the river would
have to climb thousands of feet uphill to get over preexisting strata
to the east of the present Grand Canyon. I haven’t seen the Science
article, but there may be a great deal of misinterpretation about what it does say.
As outlined in the model given here (which has been posted
on the Internet since 2001 – for example, see http://web.archive.org/web/20020308011932/http://www.geocities.com/durangobill/Paleorivers_preface.html
), there was erosion going on ABOVE the
current western Grand Canyon some 60 million years ago. Sixty million
years ago, there was a river system that originated near the present
Arizona/California border that continued northeastward to Wyoming. Rim
Gravels show that 60 million years ago, river flow was from south to
north just to the north of the Peach Springs, AZ area.
This river system (and is tributaries) eroded away
Mesozoic rock layers from over the current Grand Canyon area and
redeposited them from Utah northeastward into Wyoming. If this is
consistent with the model presented in the Farley/Flowers journal
article, then we are in full agreement.
Also, the ancestral Peach Springs, AZ to Bryce Canyon,
Utah river flow patterns of the western Grand Canyon area presented
here are virtually identical to those shown in Fig. 5 of Wayne Ranney’s
2008 “A proposed Laramide proto-Grand Canyon” article published in Geomorphology
The “Spillover” Model
This paper attributes the cutting of the present Grand
Canyon to the arrival and spillover of the Colorado River about 5.4
million years ago. In the years since this paper was first posted on
the Internet in April 2001, there have been multiple papers that
support this model.
“supports a lake-spillover hypothesis for initiation of the lower Colorado River.”
“Stratigraphic evidence for the role of lake spillover in the inception of the lower Colorado River” http://specialpapers.gsapubs.org/content/439/335.abstract
“Lake-spillover models for the lower Colorado River (House and others; Howard) are increasingly well-documented” (Page 8)
“Robust Geologic Evidence for latest Miocene-earliest Pliocene River
Integration via Lake-spillover along the lower Colorado River” (Page
Links to the
Evolution of the Colorado River and its Tributaries
Appendix to the Evolution of the Colorado River
(Suggest you print this. Please allow a few
seconds to download.)
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 (Links updated July 27, 2008)
Low Resolution (1125w x 1450h) - 326 KBhttp://veimages.gsfc.nasa.gov/1980/FourCorners.A2001162.1815.1km.jpg
Medium Resolution (2250w x 2900h) - 1.4 MBhttp://veimages.gsfc.nasa.gov/1980/FourCorners.A2001162.1815.500m.jpg
High resolution (4500w x 5800h) - 4.3 MBhttp://veimages.gsfc.nasa.gov/1980/FourCorners.A2001162.1815.250m.jpg
Animated Movies (with
Southwest U. S. and North American Paleogeography
Maps by Ron Blakey - animation by Steve Perrin
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.
This research paper was first posted on the Internet in April 2001. To
see what my home page looked like in Nov. 2001, click here. http://replay.waybackmachine.org/20011119013229/http://www.geocities.com/durangobill/
Then click on the “Evolution of the Colorado River” link to see the earliest version that was saved in the “Way Back Machine”.
(or click here: http://replay.waybackmachine.org/20020308011932/http://www.geocities.com/durangobill/Paleorivers_preface.html
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