(Note: This entire paper was (is
being) updated in April/May, 2005. The primary changes
1) Changed the “overflow” date of the Colorado River from 5.5
million years ago to 5.4 million years ago. (Only notations
for this change existed in the old version.)
2) Changed the river reversal date in Wyoming from about 30
million years ago to 20-25 million years ago. (Only notations
for this change existed in the old version.)
3) Added better illustrations to the various pages.)
This paper is an attempt to model the geologic
history of the Colorado River and its tributaries starting
with the Late Cretaceous through the present. In addition to
the large scale Colorado River system, local features near
Durango, CO are also covered.
Several of the conclusions presented here
disagree with currently accepted interpretations. As for the
origin of the Grand Canyon, none of the existing models seems
to provide an adequate explanation and a new model is
proposed. Colorado’s Gore Range and White River Plateau appear
to be of recent origin (Miocene) instead of Laramide time.
Also, the ancestral San Juan River has undergone wide
variations before establishing its current path
The model also examines features near Durango,
Colorado (see the appendix). These include: 1) The origin of
the Bridge Timber Mountain gravel deposits (which appear to be
much older than the accepted age); 2) How and why the La Plata
River bisects the La Plata Mountains; and 3) What formed the
“Dry Valley” north of Durango.
Events are presented in chronological order with
general overviews of river systems for each geological epoch.
Where there are differences from published conclusions,
special sections in the appendix discuss arguments and
evidence to support the model. The most appealing part of the
model is the sense that the pieces seem to form a logical
sequence, and components that previously were unexplained seem
to fit together properly.
As the chronology progresses, a pattern emerges
where many locations throughout the southwest have undergone
multiple distinct periods of local uplift. This does not fit
the standard models of mountain building, which classically
falls into one of two camps. Normal mountain building is
usually caused by, (1) either plate convergence and subduction
which produces compression and thrusting or, (2) plate rifting
due to doming within the mantle accompanied by fault block
mountain building (a better description is valley dropping).
At the end of the appendix, a theory is presented to explain
the phenomenon of multiple distinct local uplifts in a given
Major references include:
1) Dr. Ron Blakey’s historical geology depictions
2) “Grand Canyon Geology” (1990 Printing) by Beus and
3) “Roadside Geology of Arizona” (1993 Printing) by
4) “Roadside Geology of Colorado” (1992 Printing) by
5) “Roadside Geology of New Mexico” (1995 Printing) by
6) “Roadside Geology of Utah” (1994 Printing) by Halka
7) “Roadside Geology of Wyoming” (1998 Printing) by
Lageson and Spearing
8) “Field Trip Guidebook” by The Department of Geology,
Fort Lewis College
9) “Grand Canyon The Story Behind The Scenery” by
10) Geologic maps at: http://geology.about.com/science/geology/cs/geomapsusstates/index.com
11) “Geologic Map of Colorado” Compiled by Ogden Tweto
12) High altitude photos and USGS topographic maps at: http://terraserver.microsoft.com/
13) Additional topographic maps at: http://www.topozone.com
14) 2-D and 3-D computer images and maps generated by
Topo USA v. 2.0 by Delorme
15) Detailed USGS topographic maps of Colorado by
Delorme’s 3-D Topo Quads
16) Grand Canyon Symposium 2000 abstracts: http://wwwflag.wr.usgs.gov/GCSymposium/
exist in this area during the Cenozoic?
The first question that must be asked concerns
the existence of river systems during this period. The
Colorado River Basin is a dry area today with most river water
supplied by runoff from high mountain systems (which were
generally lower during most of the Cenozoic). It is therefor
useful to provide evidence that sufficient water was present
in the past to support river systems; and in particular, if
there was drainage exiting the Colorado Plateau to other
During the Paleocene and Eocene Epochs, a large
lake (or series of lakes) about the size of Lake Ontario
developed in southern and central Utah, and with time it
(they) extended northeastward into Colorado and Wyoming.
During the same time span, sediments brought in from somewhere
else buried most of Wyoming’s Laramie Range and Owl Creek
Mountains. This would require a large river system. During the
early Oligocene, the climate was wet enough to support large
Sequoia trees next to a lake just east of the Colorado Plateau
at Florissant Fossil Beds National Monument. During the late
Oligocene and through most of the Miocene it was drier, but
rivers still dissolved a lot of salt from the old Paradox
Basin area and deposited it in western and northwestern Utah.
We note that this is the only time period that had significant
salt accumulation; thus any other salt dissolved in river
systems must have exited the area without being left behind in
evaporative basins. Thus, we conclude that major river systems
existed throughout the Colorado Plateau area, and the next
problem is to try to deduce where they were.
run uphill to get across mountains?
There are many locations throughout the western
U.S. where rivers have cut canyons through mountain ranges
instead of taking easier, lower routes around them. For
example, the Wasatch Range near Salt Lake City is of recent
origin and is still rising. Yet, rivers such as the Weber,
Ogden, and Provo cut right through the range producing canyons
thousands of feet deep. We can conclude that the rivers were
in place first; and as the mountain range rose, the rivers
acted as stationary band saws cutting deep groves into the
rising block. There are examples where even arroyos have cut
canyons through rising blocks. For example, east of
Albuquerque, NM, highway I-40 uses Tijeras Canyon cut by
Tijeras Arroyo through the Sandia Mountains. This leads to the
following important rule. An established river (or stream or
even an arroyo) is frequently capable of maintaining its path
through a rising mountain range.
Alternately, a river may try to maintain a path
through a rising mountain mass but eventually be forced to
abandon this channel. An example of this phenomenon is Unaweep
located high on the Uncompahgre Plateau southwest
of Grand Junction, Colorado. An ancient river was here (will
be identified later), but long ago it found an easier route.
It is also possible to have both events occur at
the same location over a period of time if the mountain range
has several distinct periods of uplift. A river may be able to
maintain a canyon during a first uplift and then abandon it
during a second uplift. Such a combination would only happen
rarely, but should subsequent events reactivate this ancient
canyon millions of years later, it would be a geologic grand
What happens to water if it exists on a slope?
The obvious answer is - it runs downhill. More precisely,
unless there is some obstruction, it runs directly downhill at
right angles to the contour lines that appear on topographic
maps. This leads to another important rule. When a river
(stream, etc.) first develops, it will take the easiest
downhill path that is available. If a modern river follows a
more illogical course, it is because it (or a related
predecessor) became entrenched in an ancestral easier course,
and has resisted changes produced by subsequent erosion,
mountain uplifts, etc. The illogical course of the river has
thus preserved a record of the old topography. Equally
important, if there are stream deposits, paleovalleys, etc. in
areas that are now at higher elevations not occupied by
current rivers; then these areas (and any linked strata) must
have been lower at some time in the past.
If a river uses bits and pieces of an ancestral
drainage established during some earlier topography and then
integrates these with drainage derived from current
topography; it can produce some rather bazaar results. For
example, both the Laramie Range in Wyoming and the Gore Range
in Colorado contain streams that start down one side of the
mountain range, and then make 180-degree turns back through
the crest of the range to flow down the other side. In both of
these ranges, the sections of the streams that reverse back
through the crests are remnants of ancestral rivers. This
double-back phenomenon shows up frequently in other locations
throughout the southwest.
There are two dominant sequences of events that
govern why current river systems exist in areas that are not
favored by present topographical terrain. Either: (1) The
river system was entrenched BEFORE subsequent tectonic and
erosional events produced changes (a process called
“antecedence”); or (2) The earlier topography was subsequently
covered by sediments, a new river course developed across
these sediments, and finally the river eroded downward into
the old terrain BEFORE the surrounding silt/sediments could be
washed away ( a process called “superimposition”). Both of
these processes contributed to current river patterns
throughout the Colorado Plateau.
Combinations of these rules can be used to deduce
the relative order of tectonic and erosional events
controlling the current paths of rivers, streams, arroyos,
etc. Some examples of present rivers (and old deposits) not
flowing directly downhill (smoothed topographically and/or
stratigraphically) and other unexplained recent sedimentary
formations include: (Illustrations and more details are
provided in the Appendix and “Image Index” pages for many of
a) The Colorado River flows almost parallel to the
smoothed contour lines on the west side of the Kaibab Plateau
b) The Colorado River flows stratigraphically uphill on
the east side of the Kaibab Plateau. For that matter, it flows
stratigraphically uphill for most of its path across southern
Utah and northern Arizona.
c) Kanab Creek has cut its own canyon en route to
joining the Colorado in the Grand Canyon. If it established
this route based on current topography, it would have had to
flow uphill at least 1,200 vertical feet.
d) The Paria
(in northern Arizona) cuts across (and 2,500 feet
down through) the Paria Plateau instead of taking an easier
route further north.
e) Tsaile Creek flows parallel to the smoothed contour
lines on the north side of Canyon
f) West of Mexican Hat, Utah, the San Juan River cuts
instead of going around it. Thus, we have Cedar
Mesa to the north and Douglas Mesa (capped by old river
deposits) to the south.
g) Just to the east of Escalante, Utah, the Escalante
River has carved a 1,000 foot deep canyon through a mesa
instead of taking a much easier route to the southeast.
h) From Dolores, CO to Gateway, CO, the Dolores River
cuts across terrain that no river in its right mind would seek
i) Upstream from Dolores, CO, the Dolores River cuts
diagonally across contour lines from Stoner (the forks) to
j) Tributaries entering the West Dolores River from the
west flow stratigraphically uphill. (Also uphill across the
smoothed topographic contours.)
k) All the major rivers in eastern Utah (Colorado, Dirty
Devil, Escalante, Green, and San Juan) have entrenched
meanders (goosenecks) indicating that at some point in the
past they meandered lazily across silt flats.
l) At some point in the past, a large river formed Unaweep
across the Uncompahge Plateau in Colorado, yet
the canyon is dry today. There are two other similar high dry
valleys crossing the Gore Range and another parallel to the
Colorado River in the southwest section of the Grand Canyon
m) A deep canyon (used by highway I-70) cuts east to
west through the Wasatch Plateau in Utah. Salina Creek
opportunistically uses this old canyon, but its origin is far
n) Several rivers including the Price cut across Utah’s
San Rafael Swell (Reef) oblivious to contours that should have
directed them elsewhere.
o) The Price
slices into the Book Cliffs north of Green River,
Utah instead of taking a much easier route a few miles further
to the southwest. Even more interesting, this illogical course
contains entrenched meanders.
p) The Green River cuts through the Tavaputs
north of Green River, Utah - thus forming the
deepest canyon in Utah.
q) The Green/Yampa river system slices through Split Mountain
in the northeast corner of Utah.
r) The Green River cuts through the eastern Uintas to
form the Canyon
, but topographically the river should be
s) The late Miocene age Browns Park Formation covers
parts of northwestern Colorado. The “Roadside Geology of
Colorado” offers no explanation as to how it got there.
t) The Colorado River cuts through the northwest side of
the La Sal Mountains (in Utah) instead of going around them.
u) A resolution to the origin of the Chuska Sandstone.
The “Roadside Geology of New Mexico” and other sources had
noted its existence along with an age estimate of early/mid
Tertiary, but explanations of how it was deposited were not
v) The Colorado River has cut deep canyons through the Gore Range
(southwest of Kremmling, CO) and across the White River
w) Both Colorado’s Gore Range and Wyoming’s Laramie
Range have streams that start down one side of range and then
make 180-degree turns to go back through the crest of the
range to flow down the other side.
x) The White River cuts into the north side of the White
River Plateau. Of greater interest, Big Beaver Creek flows
stratigraphically (and smoothed topographically) uphill into
the plateau to join the White River.
y) The La Plata
form a north-south range near Durango, CO. The
La Plata River runs north to south bisecting most of the range
just where its crest should be.
z) A lot of “old” salt has been dissolved out of the
Paradox Basin. A lot of “new” salt exists in northwest Utah.
Something transported it.
We will try to fit ALL of these puzzle pieces together in a
Arithmetic Regarding Erosion Rates
The history of the Grand Canyon indicates a major
break point in river patterns occurred about 5.4 (+/-4%)
million years ago (see Beus and Morales). (Added 8/9/05:
Latest evidence (at http://gsa.confex.com/gsa/2005AM/finalprogram/abstract_91054.htm
narrows this further to 5.36 +/-0.06 million years ago)
It is most helpful to do a little arithmetic regarding erosion
rates so that we may run the clock backward to reconstruct the
topography of 5.4 million years ago. The result makes it much
easier to discard preconceived ideas.
Before the Glen Canyon Dam was built, the average
sediment transport rate through the Grand Canyon (measured
near Phantom Ranch) was 391,780 tons per day. (Beal page 10.
Beus and Morales give a figure of 300 tons per day on page
334, but calculations for lava dam fill rates require the much
larger number. It appears the “thousands” designation was lost
somewhere in the pipeline regarding the page 334 data.).
If we use 391,780 tons per day and a weight of
140 Lbs/CuFt for sandstone (Handbook of Chemistry and
Physics), then we get an average sandstone erosion rate of 5.6
million cubic feet per day for the Colorado River Basin. Then,
we multiply this result by 5.4 million years and divide by
the137,641 sq. miles of contributing drainage area (USGS
station # 09402500 – near Phantom Ranch) to arrive at 2,877
feet of erosion for the entire river basin over the last 5.4
It is probable that this figure is too large for
a couple of reasons. First, erosion rates throughout the
southwest seem to have increased after 1880. Since sediment
transport measurements in the Grand Canyon started after this,
the true long-term rate is probably lower. Second, prior to
two million years ago, rainfall rates were lower due to the
pre ice age climate. (Beyond 5.4 million years ago erosion
rates were probably much lower).
However, a ballpark estimate of 1,500 feet of
erosion seems quite reasonable for the last 5.4 million years.
If we restore this sediment to the present landscape, we can
fill every canyon in the entire Colorado River basin and have
as much as 1,000 ft. or so left over to cover up current
surface features. For example, the Island in the Sky area in
Canyonlands National Park, the Book Cliffs north of Green
River, Utah, and the Paria Canyon area of Arizona were not
exposed yet as of 5.4 million years ago. Erosion formed and
exposed these features in just the last 5.4 million years. We
can thus conclude they (and other recent features) had no
influence on river paths before this time. This allows much
more freedom for the placement of earlier river systems. For
example, imagine marking off the area currently bounded by the
Grand Canyon to the south, the Colorado/Utah border to the
east, Green River, Utah to the north, and the Wasatch to the
west. Prior to 5.4 million years ago, ALL river systems within
this area followed different courses than they do at present.
The sediment that has been eroded during this
time has been deposited in the growing rift along the
Arizona/California border extending southward through Mexico
to include the northern quarter of the Gulf of California.
(See Eugene Singer’s monograph at http://web.archive.org/web/19991008060017/www.aloha.net/~esinger/homegeol.htm
Another section of the rift that has been filled in extends
100 miles northwestward to include the Salton Sea. These
deposits have been measured at up to six miles thick (in the
northern Gulf of California). Four to five million years ago
the Los Angeles Basin would have been 100 to 150 miles
southeast of where it is now. It is possible some of the early
Colorado River deposits may have helped to fill it in.
Local uplift within the last few million years is
also significant when reconstructing earlier topography.
Everyone knows the Wasatch has risen during this period.
(Later, we will provide a measurement of how much). Equally
important, there is evidence that the Kaibab Plateau has had
three separate uplifts starting with the Laramide. The most
recent uplift is probably still in progress today. (We will
document this later.) These are all components as to how the
Colorado River relocated to its present course in the Grand
Continue to Part 2 - Late
Cretaceous through the Eocene
Return to Evolution of the
Colorado River Main Page
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