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Note: Alaska and Hawaii are shown out of
position for reference only and are not to scale.
Blank
California State Outline Map
The
Geography of California is rich and diverse. There
are alpine mountains, foggy coastlines, hot deserts,
and a fertile central valley. The
U.S. state of
California is home to the
world's tallest (coast
redwood), most massive (Giant
Sequoia), and oldest (bristlecone
pine) trees. It is also home to both the highest
(Mt. Whitney) and lowest
(Death Valley) points in
the 48
contiguous states.
The state
is generally divided into
Northern and Southern
California, although the boundary between the two is not
well defined. San Francisco is decidedly a Northern
California city and Los Angeles likewise a Southern
California one, but areas in between do not often share
their confidence in geographic identity. The US Geological
Survey defines the geographic center of the state at a point
near North Fork,
California.
Earth
scientists typically divide the state into eleven distinct
geomorphic provinces with clearly defined boundaries. They
are, from north to south, the Klamath Mountains, the Cascade
Range, the Modoc Plateau, the Basin and Range, the Coast
Ranges, the Central Valley, the Sierra Nevada, the
Transverse Ranges, the Mohave Desert, the Peninsular Ranges,
and the Colorado Desert. For purposes of explanation, it is
also helpful to recognize the Los Angeles Basin, the Channel
Islands, and the Pacific Ocean as distinct regions.
Northern California
Klamath Mountains
The
Klamath Mountains are a
mountain range in northwest California and southwest Oregon,
the highest peak being
Thompson
Peak (2,744 m / 9,002 ft) in
Trinity County,
California. They have a very varied geology, with
substantial areas of serpentine
and marble, and a climate summers with
limited rainfall. As a consequence of the geology, they have
a unique flora including several endemic or near-endemic
species, such as Lawson's
Cypress (Chamaecyparis lawsoniana),
Foxtail Pine (Pinus balfouriana),
Brewer's Spruce (Picea
breweriana) and Kalmiopsis (Kalmiopsis
leachiana).
Cascade Range
is a
mountainous region stretching from
British Columbia in Canada
down to the northern part of California. The Cascades (as
they are called for short) are part of the Pacific Ring of
Fire, the ring of volcanoes around the Pacific Ocean. All of
the known historic eruptions in the contiguous United States
have been from Cascade volcanoes. The last Cascade volcano
to erupt in California was Lassen
Peak, which erupted from 1914 to 1921. Lassen is the
most southerly active volcano of the Cascade chain.
This region
is located in the northeastern section of the state
bordering Oregon and
Nevada, mostly north of the Central Valley and the
Sierra Nevada mountain range. The area is centered on
Mount Shasta, near the
Trinity Alps. Mount Shasta is a
dormant volcano, but there is some evidence that it or
Shastina, a smaller companion,
erupted in the 18th Century.
Modoc Plateau
In the
northeast corner of the state lies the
Modoc Plateau, an expanse of
lava flows at an altitude of 4,000 to
6,000 ft (1,200 to 1,800 m) with
cinder cones, juniper flats,
pine forests, and seasonal lakes. Nearly
1 million acres (4,000 km²) of the
Modoc National Forest
lie on the plateau between the
Medicine Lake Highlands
in the west and the Warner
Mountains in the east. The plateau supports large herds
of mule deer (Odocoileus
Hemionus),
Rocky Mountain Elk (Cervus Canadensis), and
pronghorn antelope (Antilocapra
Americana). There are also several herds of wild horses
on the plateau. The
Clear Lake National Wildlife Refuge and
Long Bell
State Game Refuge are located on the plateau as well.
The Lost River watershed drains the north part of the
plateau, while southern watersheds either collect in basin
reservoirs or flow into the large Big Sage Reservoir, which
sits in the center of Modoc County.
Basin and Range
To the east
of the Sierra is the
Basin and Range geological province, which extends into
Nevada. The Basin and Range is a
series of mountains and valleys (specifically
horsts and
grabens), caused by the extension of the Earth's crust.
One notable feature of the Basin and Range is
Mono Lake, which is the oldest lake
in North America. The Basin and
Range also contains the Owens Valley,
the deepest valley in North America (more than 10,000 feet
(3 km) deep, as measured from the top of Mount Whitney).
In the
eastern part of the state, below the Sierra Nevada, there is
a series dry lake beds that were filled with water during
the last ice age (fed by ice melt from
alpine glaciers but never directly affected by
glaciation). Many of these lakes
have extensive evaporite deposits
that contain a variety of different salts.
In fact, the salt sediments of many of these lake beds have
been mined for many years for various
salts, most notably borax (this is most
famously true for Owens Lake and
Death Valley).
In this
province reside the
White Mountains, which are home to the oldest living
thing in the world, the
bristlecone pine.
Coast Ranges
To the west
of the Central Valley lies the
Coast Ranges,
including the Diablo Range, just east of
San Francisco, and
the Santa Cruz Mountains,
to the south of San Francisco. The Coast Ranges north of San
Francisco become increasingly foggy and rainy. These
mountains are noted for their coast
redwoods, which live within the range of the coastal
fog, the tallest trees on Earth.
Central Valley
California's geography is largely defined by its central
feature — the Central
Valley, a huge, fertile valley
between the coastal mountain ranges and the
Sierra Nevada with the
exception of the Sutter Buttes
mistakenly referred to as "The Smallest Mountain Range in
the World" located approximately 10 miles (16 km) northwest
of Yuba City. The northern part of
the Central Valley is called the
Sacramento Valley, after
its main river, and the southern part is called the
San Joaquin Valley, after
its main river. The whole Central Valley is watered by
mountain-fed rivers (notably the
San Joaquin,
Kings, and
Sacramento) that drain to
the San Francisco Bay
system. The rivers are sufficiently large and deep that
several inland cities, notably
Stockton, California,
are seaports.
The
southern tip of the valley has interior drainage and thus is
not technically part of the valley at all.
Tulare Lake, once 570 square
miles (1,476 square kilometers) and now dry and covered with
agricultural fields, once filled much of the area.
Sierra Nevada
In the east
of the state lies the Sierra
Nevada, which runs north-south for 400 miles (600 km).
The highest peak in the continental United States,
Mount Whitney at 14,505 feet
(4,421 m), lies within the Sierra Nevada. The topography of
the Sierra is shaped by uplift and glacial action.
The Sierra
has 200-250 sunny days each year, warm summers, fierce
winters, and varied terrain. The rare combination of rugged
variety and pleasant weather leads many mountaineers to say
that they are the most beautiful and accessible mountains in
the world. The famous Yosemite
Valley lies in the Central Sierra. The large, deep
freshwater Lake Tahoe lies to the
North of Yosemite. The Sierra is also home to the
Giant Sequoia, the most massive
trees on Earth.
These
features inspired the founding of the
Sierra Club and the Alpine Club,
public-service clubs of mountaineers devoted to maintaining
trails and lodges and organizing outings to explore the
Sierra. The most famous hiking and horse-packing trail in
the Sierra is the John Muir Trail,
which goes from the top of Mt. Whitney to Yosemite valley,
and which is part of the
Pacific Crest Trail that goes from
Mexico to Canada.
The three
major national parks in this province are
Yosemite National Park,
Kings Canyon National
Park, and Sequoia
National Park.
Southern California
Transverse Ranges
Southern California is
separated from the rest of the state by the east-west
trending Transverse Ranges,
including the Tehachapi,
which separate the Central Valley from the
Mojave Desert. Urban Southern
California intersperses the valleys between the
Santa Susana Mountains,
Santa Monica Mountains
and San Gabriel Mountains,
which range from the Pacific Coast, eastward over 100 miles
(160 km), to the San
Bernardino Mountains, north of
Palm Springs. The
highest point of the range is
Mount San Gorgonio at 11,502 feet (3,506 m). The San
Gabriel Mountains have
Mount Wilson observatory, where the
redshift was discovered in the 1920s.
The
Transverse Ranges include a series of east-west trending
mountain ranges that extend from Point Conception at the
western tip of Santa Barbara County, eastward (and a bit
south) to the east end of the San Jacinto Mountains in
western Riverside County. The Santa Ynez Mountains make up
the westernmost ranges, extending from Point Conception to
the Ventura River just west-northwest of Ojai, in Ventura
County. Pine Mountain Ridge, Nordhoff Ridge-Topatopa
Mountains, Rincon Peak-Red Mountain, Sulphur Mountain, Santa
Paula Ridge, South Mountain-Oat
Mountain-Santa Susana Mountains, Simi Hills, Conejo
Mountains-Santa Monica Mountains are all part of the Western
Transverse Ranges, in Ventura and western Los Angeles
Counties.
The Liebre
Mountains occupy the northwest corner of Los Angeles County,
and represent a northwestern extension of the San Gabriel
Mountains, both on the Pacific Plate side of the San Andreas
Fault. The fault divides the San Gabriel Mountains from the
San Bernardino Mountains further to the east in San
Bernardino County.
It is
possible to surf in the
Pacific Ocean and
ski on a mountain during the same winter
day in Southern California
(but it takes planning to avoid the traffic congestion).
Los Angeles Basin
For the
last 15 million years, the Los
Angeles, San Gabriel,
and Santa Ana Rivers have
deposited sediment from the Transeverse Ranges along the
southern coast of California. That sediment has formed the
large, flat expanse of land known as the
Los Angeles Basin, on which
lives most of the population of
Los Angeles and
Orange Counties.
At its
deepest point, near where the Los Angeles River meets the
Rio Hondo, the
sediment forming the basin is 6 miles (11 km) deep. The fact
that so much sediment, which is naturally less stable than
other geologic formations, underlies Los Angeles and its
environs is one of the reasons
earthquakes are such a danger to the metropolitan area.
Mojave Desert
There are
harsh deserts in the Southeast of
California. These deserts are caused by a combination of the
cold offshore current, which limits evaporation, and the
rain shadow of the mountains. The
prevailing winds blow from the ocean inland. When the air
passes over the mountains,
adiabatic cooling causes most water in the air to rain
on the mountains. When the air returns to sea level on the
other side of the mountains, it recompresses, warms and
dries, parching the deserts. When the wind blows from
inland, the resulting hot dry föhn
winds are called the Santa
Ana Winds.
The
Mojave Desert is bounded by the
peninsular Tehachapi Mountains on the Northwest, together
with the San Gabriel and the San Bernardino Mountains on the
Southwest. These Western boundaries are quite distinct,
forming the dominant pie-slice shaped
Antelope Valley
in Southern California. The outlines of this valley are
caused by the two largest faults in California: the
San Andreas and the
Garlock. The Mojave Desert
extends Eastward into the State of Nevada.
The Mojave Desert receives less than 6 inches (150 mm) of
rain a year and is generally between 3,000 and 6,000 feet
(1,000 and 2,000 m) of elevation. Areas such as the Antelope
Valley desert which is a high desert received snow each
year, in the past it could snow 2-3 times a year; however,
recently snow level has declined significantly to once a
year or less. Most of the towns and cities in the California
portion of the Mojave are relatively small, except for
Palmdale and
Lancaster. However,
some are quite famous like
Barstow, a popular stop on the famous
Route 66. The Mojave Desert also
contains the lowest, hottest place in the
Americas:
Death Valley,
where temperature normally approaches 120 °F (49 °C) in late
July and early August.
Peninsular Ranges
The
southernmost mountains of California are the
Peninsular Ranges, which
are East of San Diego
and continue into Baja California
(Mexico) in the
Sierra San Pedro Martir.
The Peninsular Ranges contain the
Laguna Mountains, the
San Jacinto Mountains,
the Santa Ana Mountains
and the Palomar Mountain
Range, notable for its famous
Palomar observatory.
San Jacinto Peak's eastern
shoulder has a cable tram that runs from the desert floor to
nearly the top of the mountain where riders can set off
hiking or go
cross-country skiing.
Colorado Desert
To the east
of the peninsular ranges lie the
Colorado and Sonoran Deserts,
which extend into Arizona and Mexico.
One feature of the desert is the
Salton Sea, an inland lake that was formed in
1905 when a swollen
Colorado River breached
a temporary canal near the
U.S.-Mexico border and flowed into the Salton Basin for
almost two years. Today, the Salton Sea remains as
California's largest lake.
The Channel Islands
The
Channel Islands
are a group of islands off the
coast of Southern California. They are
divided into two groups, the Northern islands and the
Southern islands. There are eight islands total:
Four of the
islands are located in
Santa Barbara
County, two are located in
Ventura County,
and two are located in
Los Angeles County.
The islands have relatively few people. The only island with
a sizable settlement is
Santa Catalina, with its towns of
Avalon and
Two Harbors. The
islands of Anacapa, San Miguel, Santa Barbara, Santa Cruz,
and Santa Rosa make up the
Channel Islands
National Park. There is also a marine sanctuary in the
islands, the
Channel
Islands National Marine Sanctuary. The Channel Islands,
and in particular San Nicolas Island, are famous for the
Lost Woman of San Nicolas, or Juana
María. This woman was the main character in the book
Island of the Blue
Dolphins by Scott
O’Dell.
Pacific Ocean
The
Pacific Ocean lies to the west
of California. Sea temperatures rarely exceed 65 °F (18 °C),
even in summer, because of up-welling
deep waters with dissolved nutrients. Therefore, most sea
life in and around California more closely resembles Arctic,
rather than tropical, biotopes. The
sea off California is remarkably fertile, a murky green
filled with fish, rather than the clear dead blue of most
tropical seas. Before 1930, there was an
extremely valuable sardine (herring)
fishery off Monterey,
but this was depleted, an event later famous as the
background to John Steinbeck's
Cannery Row.
Natural hazards
California's most infamous natural hazard is
earthquakes due to the many faults
that run through California, Nevada, and the Pacific Coast.
Major historical earthquakes include:
Coastal
cities are vulnerable to tsunamis
from locally generated earthquakes as well as those
elsewhere in the Pacific
Ring of Fire. The
Great Chilean Earthquake tsunami (1960) killed one
person and caused $500,000 to $1,000,000 dollars of damage
in Los Angeles,
damaged harbors in many coastal cities, and flooded streets
in Crescent City.
Waves from the Alaskan
Good Friday Earthquake of 1964 killed twelve people in
Crescent City and caused damage as far south as Los Angeles.
The state
is subject to coastal storms,
especially during the North American
monsoon season. Dry weather during the rest of the year
produces conditions favorable to
wildfires. California
hurricanes occur less frequently than their counterparts
on the Atlantic Ocean. Higher
elevations experience snowstorms in
the winter months.
Floods are occasionally caused by heavy
rain, storms, and snowmelt. Steep slopes and unstable soil
make certain locations vulnerable to
landslides in wet weather or during earthquakes.
California
is also home to several volcanoes,
including Lassen Peak, which
erupted in 1914 and 1921, and Mount
Shasta.
Future geography
California,
when only partially explored by the Spanish, was once
thought to be an island, as when the southern peninsula of
Baja California
is approached from the Gulf of
California the land appears to the west. It is expected,
through the motions of plate
tectonics that the sea floor spreading now acting in the
Gulf of California (also known as the Sea of Cortez) will
eventually extend through Southern California and along the
San Andreas fault to below
San Francisco, finally forming
a long island in less than 150 million years. (For
comparison, this is also the approximate age of the
Atlantic Ocean.) Predictions
suggest that this island will eventually collide with
Alaska after an additional 100 million
years.
Interactive California State Map
Explore the state of California with the dynamic map below. You can
zoom, pan and even get a satellite map view.
Move your cursor over the markers on the map to
learn more about California.
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