“Asked to explain
what makes the
Colorado Plateau
unique,
geographers grow
cryptic, enigmatic,
even mystical.”
-Ray Wheeler,
“The Colorado
Plateau Region”
Colorado Plateau Province
•
Flagstaff
Mogollon
Rim
Phoenix
•
ARIZONA
Tucson
Colorado Plateau: a distinct mass of continental
crust for >500 million years
Long sedimentary history +
little deformation (long, stable history) =
“layer cake geology”
Volcanic activity
mostly confined to
edges of Colorado
Plateau
San Francisco Peaks
volcanic field near
Flagstaff
Shiprock, New
Mexico (volcanic
neck)
Major uplift of Colorado Plateau 15 - 5 million years
ago => Major downcutting by rivers => Deep
canyons, exposing the sedimentary layers
How Grand Canyon was built
EVENT
WHEN
PRODUCT
Sediments
deposited, then
buried and
metamorphosed
2 - 1.8
billion yrs
ago (bya)
Vishnu Schist
Long period of
erosion levels land
surface
1.7 - 1.6
bya
The Great
Unconformity
How Grand Canyon was built
EVENT
WHEN
PRODUCT
Sea goes in, sea
goes out... Sea
goes in, sea goes
out...
Paleozoic (590
- 250 million
yrs ago (mya)
Thick sequence
of marine
sandstones,
shales,
limestones
Mountainbuilding in
Rockies sheds
sediments onto
Colo. Plateau
Mesozoic (250
- 65 mya)
Thick sand dune
deposits, e.g.
Navajo
Sandstone
How Grand Canyon was built
EVENT
WHEN
PRODUCT
Colo. Plateau
uplifted;
Late
Tertiary/Early
Quaternary
(~15 - 5 mya)
Softer Mesozoic
sediments stripped
off harder surface
of Kaibab
Limestone

Streams,
Colo. River
vigorously
downcut
through
Plateau
~5 mya to
present
Deep canyons
expose one of
greatest
pC/Paleozoic rock
sequences in world
Bright Angel Shale
Tapeats Sandstone
Vishnu Schist
Great Unconformity
Zion National Park and vicinity: younger
(Mesozoic) rocks that overlie Grand Canyon
sequence-- mostly cross-bedded sandstones
Most of Colo. Plateau
(except higher
elevations) is desert
Contains elements of the
4 major desert types
Region
experiences
summer
monsoons
Colorado Plateau’s mean elevation = 5200 ft. (1730 m);
range = 3000 - 14,000 ft. (1000 - 4670 m)
High elevation + deep canyons => huge elevational/
climatic gradients
Merriam developed life zone concept on the Colorado
Plateau:
Lower Sonoran
Zone, Inner
Grand Canyon
80 miles (130 km)
apart
Boreal Zone,
San Francisco
Peaks
A virtual hike down the Bright Angel Trail
On the South Rim:
pinyon-juniper
woodland
In mesic microsites
on South Rim:
Ponderosa pine
Descending from Rim.....
In mesic
microclimates
(north-facing
slopes) below
Rim: Douglas fir
Drier woodland:
mostly juniper
Descending further......
On Tonto Plateau:
Coleogyne
(blackbrush)
community
Hedgehog cactus
Utah agave
Inner Canyon:
Sonoran desert
Mesquite tree
Sacred Datura
Barrel cactus
North Rim and North Kaibab National Forest
More mesic (heavy
winter snowfall)
Ponderosa pine,
aspen, spruce, fir
Mojave Desert
(west/SW of
Colorado Plateau)
Creosotebush
Desert tortoise
A quick tour of some Colorado Plateau fauna
Desert bighorn sheep
Mule deer
Canyon wrens
Wild turkey
Chuckwalla
Horned toad
Collared lizard
Grand Canyon
rattlesnake
Humans at Grand Canyon and
vicinity
 10,000 years ago : Paleoindians at Grand
Canyon
 3000-4,000 years ago : Desert Culture at the
Canyon
Split-twig
figurine
 500 - 1200 A.D. :
Prehistoric Pueblo Peoples
(Anasazi) in the Canyon
(ancestors to modern Hopi)
Anasazi Bridge
Hilltop ruin,
Cardenas Creek
 1540 : First Europeans (Captain Garcia Lopez de
Cardenas) visit Canyon with Hopi guides
 1869 : Major John Wesley Powell leads first
successful expedition down the Colorado River
Tau-gu and
J.W. Powell
Powell’s boat and
armchair
 1871 : Mormon patriarch John D. Lee establishes
Lee’s Ferry at Marble Canyon
 1877 : John D. Lee executed for his role in 1857
Mountain Meadow massacre; Emma Lee (one of his
many widows) runs ferry after his demise
1880 : 1st tourist facility (log cabin) built at South Rim
1883 : John Hance, first Grand Canyon settler, arrives
1889: C.H. Merriam explores Grand Canyon region,
develops life zone concept
1908 : President Teddy Roosevelt creates Grand
Canyon National Monument
1915 : Annual visitation
to the Canyon reaches
106,000
1919 : Grand Canyon
and Zion both become
national parks
ca. 1920 : mule
trips for tourists into
Grand Canyon
1st
1922 : Phantom Ranch built at
bottom of Grand Canyon
(designed by architect Mary
Jane Colter)
1955 : Bill Beer and John
Dagget swim entire length
of Grand Canyon (Beer
later writes book We
1938 : Elsie Clover and
Lois Jotter conduct
botanical survey as 1st
women to float Grand
Swam the Grand Canyon:
Canyon on a commercial The story of a cheap
trip
vacation that got a little out
of hand)
1955 : Georgie White pioneers use of inflatable
rafts in Grand Canyon; commercial river
running takes off
1956 : Construction of Glen
Canyon Dam is authorized
1963 : Gates of Glen Canyon
Dam close, the Colorado River
ceases to be a wild river
through Grand Canyon
 1964 : Bureau of Reclamation plans dam
within Grand Canyon; Sierra Club leads
successful fight against it
1983 : Record spring runoff
in Colorado River basin
causes flood that nearly takes
out Glen Canyon Dam:
Sheets of plywood extend
height of dam 4 ft., enough
to prevent water from overtopping dam
3 dory boatmen on illegal
trip set unmotorized speed
record: 277 miles in 3 days
1989 : Congress requires operators of Glen Canyon
Dam to assess dam operations and ways to minimize
impacts to the Grand Canyon
1993 : Suicides
(leaping/driving off Rim) at
Grand Canyon soar following
release of movie Thelma and
Louise
1996 : 1st captivitybred California
condors released into
wild near Marble
Canyon
2004 : 1st PEL Semi-occasional Phytogeographic
and Hiking Expedition to Grand Canyon area
Acknowledgements
Thanks to Bob
Ribokas’ excellent
website,
www.kaibab.org
...and to many other
websites from which
I stole, I mean
borrowed images