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
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
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
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
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.
The Geological Society of America
2005 Salt Lake City Annual Meeting (October 16–19, 2005)
Salt Lake City, Utah
“TERMINAL MIOCENE ARRIVAL OF COLORADO RIVER SAND IN THE
SALTON TROUGH, SOUTHERN CALIFORNIA: IMPLICATIONS FOR
INITIATION OF THE LOWER COLORADO RIVER DRAINAGE”
“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
there may be a great deal of misinterpretation about what it
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
Jan.28, 2014 update:
A paper published in “nature geoscience” http://www.nature.com/ngeo/journal/vaop/ncurrent/full/ngeo2065.html
“Formation of the Grand Canyon 5 to 6 million years ago
through integration of older palaeocanyons”
adds some thermochronology dating to ancestral drainage over
the Grand Canyon area. The model given here has no problems
with this newer information.
The following quote is from http://www.nature.com/ngeo/journal/v7/n3/full/ngeo2065.html
“Thus, although parts of the canyon are old, we conclude that
the integration of the Colorado River through older
palaeocanyons carved the Grand Canyon, beginning 5–6 million
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 137)
Links to the
Evolution of the Colorado River and its
Appendix to the Evolution of the Colorado
Cenozoic River Maps
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
Photographs of the Colorado River Basin
View area extends from the Gulf of California to central
Photographs taken June 6, 2001 (Links updated July 27, 2008)
Low Resolution (1125w x 1450h) - 326 KB
Medium Resolution (2250w x 2900h) - 1.4 MB
High resolution (4500w x 5800h) - 4.3 MB
Movies (with classical music)
Southwest U. S. and North American Paleogeography
Maps by Ron Blakey - animation by Steve Perrin
River Systems of the World
Also, please see “Ancestral
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
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
(or click here: http://replay.waybackmachine.org/20020308011932/http://www.geocities.com/durangobill/Paleorivers_preface.html
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