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Basin & Range / Mojave Desert
Basin & Range
vs. Great Basin
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An overview of the last horst
Basin and Range / Mojave Desert
Summary:
• Granitic, volcanic, marine sedimentary,
non marine sedimentary, metamorphic
• Horst and Graben structure, fault block
mountains. A recent geologic event
• Great Basin is part of this province
• The Basin and Range extends into
Nevada, Arizona, northern New Mexico,
western Utah and southern Idaho
• Has very old and very young rocks
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The Colorado Plateau
130,000 square miles (337,000 square km)
Bryce Canyon National Park
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The Wave, a sandstone formation located on
the Colorado Plateau in the Vermilion Cliffs
Wilderness Area, near the Arizona-Utah border.
The Great Unconformity within the Grand Canyon's Inner Gorge
The time gap within the contact is 1.2 billion years, more time than
it took to form all of the canyon's layers.
Grand Canyon National Park
Zion National Park
Colorado Plateau Summary:
• Mostly marine sedimentary and volcanic rock some
igneous and metamorphic rock
• A high standing crustal block of relatively
undeformed rocks, dissected by long north south
faults
• Consists of broad open folds, volcanic features and
consolidated sedimentary rock
• Approximately 5 million years ago the entire Rocky
Mountains and Colorado Plateau were uplifted
4,000 to 6,000 feet.
The Salton Trough
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North American Western Plate Boundary – Oligocene to
Present
● Mud pots gurgle and bubble, a sign of the geological activity going on underneath.
● These mud volcanoes and pots are located in the Brawley Seismic Zone, an area 25
miles long that extends from Brawley through Calipatria up to Bombay Beach.
162 mi.
Water from the
Pacific ocean
flowed into the
rift valley,
creating what is
now the Gulf of
California
Northern tip
begins the Salton
Trough
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Salton Trough Summary:
• Mostly non marine sedimentary and volcanic
rock at surface, marine sedimentary below
• A structural basin, a continental rift, the
northern extension of the Gulf of CA
• Basin is filled with over 5 Kilometers of
marine and non marine sediment
• Fault scarps and rifts, high heat flow, seismic
and volcanic activity common
Old Shoreline of Lake Cahuilla,
Santa Rosa Mountains near the Salton Sea
Transverse Ranges
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Basins and Valleys
Santa Clara River
• 116 miles long
• Watershed is ~1,600
square miles
• Maximum annual
streamflow ~109 cubic
meters per year and
~100 million tons of
sediment deposited in
Santa Barbara Channel
The Transverse Ranges can be divided
into three main regions that share similar
geologic characteristics:
-Western Transverse Ranges
Santa Ynez Mountains, Mountains of Central Ventura County
-Central Transverse Ranges
San Gabriel Mountains, Santa Monica Mountains, Channel
Islands, Los Angeles Basin
-Eastern Transverse Ranges
San Bernadino Mountains and Little San Bernadino Mountains
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Peninsular Range
Satellite Image showing
airflow patterns of the
Santa Ana Winds in
Coastal Southern
California
map
Satellite Image showing the Santa Ana Winds and
their contribution to the spreading of wildfires in
Southern Coastal California
San Jacinto & Elsinore Faults
Transverse Ranges Summary:
CHANNEL ISLANDS
• Only province with NE / SW structural trend
• All rock types common
• Rotated ~90 degrees clockwise from
Miocene to present
• Very old and young rocks, individual
mountain ranges have complex geologic
histories
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The Peninsular Range
Peninsular Range extends 880
miles south into Baja California
Peninsular Range Summary:
• Over 140 miles long in CA, but continues
to 750 miles to south
• Granitic Rocks and Marine Sedimentary
Rocks dominate
• San Jacinto Fault and the Elsinore Fault
are the dominating structural features
• Overall geologic history similar to the
Sierra Nevada
Southern Baja California
Batholith
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