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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 GorgeThe 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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Water from the Pacific ocean

flowed into the

rift valley, creating what is

now the Gulf of

California

Northern tip begins the Salton

Trough

162 mi.

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.

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Old Shoreline of Lake Cahuilla, Santa Rosa Mountains near the Salton Sea

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

Transverse Ranges

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The Transverse Ranges can be divided

into three main regions that share similar

geologic characteristics:

-Western Transverse RangesSanta Ynez Mountains, Mountains of Central Ventura County

-Central Transverse RangesSan Gabriel Mountains, Santa Monica Mountains, Channel

Islands, Los Angeles Basin

-Eastern Transverse RangesSan Bernadino Mountains and Little San Bernadino Mountains

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

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Satellite Image showing

airflow patterns of the

Santa Ana Winds in

Coastal Southern

California

Satellite Image showing the Santa Ana Winds and

their contribution to the spreading of wildfires in

Southern Coastal California

Transverse Ranges Summary:

• 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

Peninsular Range

map

San Jacinto & Elsinore Faults

CHANNEL ISLANDS

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Peninsular Range extends 880 miles south into Baja California

Southern Baja California Batholith

The Peninsular Range

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

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