The Cascade Mountains
Cascade Range is a mountainous region stretching from the
Fraser River in British Columbia, Canada down to south of Lassen
Peak, California in the Sierra Nevada mountain range. The
Cascades (as they are called for short) are part of the Pacific Ring
of Fire, the ring of volcanoes around the Pacific Ocean. They were
formed by volcanoes unlike the other mountain ranges in
California and support one still-active volcano; Lassen Peak. All of
the known historic eruptions in the contiguous United States have
been from either Cascade volcanoes or near Mono Lake. Lassen
Peak was the last Cascade volcano to erupt in California, 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 erupted in the 18th
Century
Modoc Plateau
In the northeast corner of the state lies the Modoc Plateau, an expanse
of lava flows that formed a million years ago and now lie at an altitude
of 4,000 to 5,000 feet (1,200 to 1,500 m). The plateau has many cinder
cones, juniper flats, pine forests, and seasonal lakes. The plateau lies
between the Cascade Range to the west and the Warner Mountains to
the east. The Lost River watershed drains the north part of the plateau,
while southern watersheds either collect in basin reservoirs or flow into
Big Sage Reservoir and thence to the Pit River.
Nine percent of the plateau is protected as reserves or wilderness
areas, such as the Modoc National Wildlife Refuge. The plateau
supports large herds of mule deer (Odocoileus Hemionus), Rocky
Mountain Elk (Cervus Canadensis), and pronghorn (Antilocapra
Americana). Herds of wild horses and livestock grazing have altered
the original high desert ecosystem of the plateau.
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 characterized by moderately cold
winters with very heavy snowfall, and warm very dry
summers with limited rainfall. They consist of several
small, forested ridges that are higher and steeper than
the coastal ranges farther south. These ridges are
separated by deep canyons and valleys. 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) and
Foxtail Pine (Pinus balfouriana). Brewer's Spruce (Picea
breweriana) and Kalmiopsis (Kalmiopsis leachiana) are
relict species, remaining since the last ice age.
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 Rosa 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.
Sierra Nevada
The Sierra Nevada range, mostly within California and barely extending into
Nevada, rises sharply from the arid basin and range on the east and slopes
gently toward the Central Valley of California on the west. The Sierra
Nevada mountain range runs about 430 miles from north to south and
forming a giant wall rising to over 14,000 feet. Vegetation at lower
elevations is dominated by lodgepole pine on the east and ponderosa pine on
the west, with fir, spruce, and alpine tundra at higher elevations.
Southern Sierra started to form in the Triassic period when an island arc
collided with the West coast of North America and raised a set of mountains.
At roughly the same time, the oceanic plate started to dive beneath the North
American plate. Magma from the melting oceanic plate rose in plumes
(plutons) from 115 million to 87 million years ago deep underground, their
combined mass forming what is called the Sierra Nevada batholith. By 65
million years ago, the proto-Sierra Nevada was worn down to a range of
rolling low mountains, a few thousand feet high.
Twenty million years ago, crustal extension associated with the Basin and
Range Province caused extensive volcanism in the Sierra. About 4 million
years ago, the Sierra Nevada started to form and tilt to the west. Rivers
started cutting deep canyons on both sides of the range. The Earth's climate
cooled, and ice ages started about 2.5 million years ago. Glaciers carved out
characteristic U-shaped canyons throughout the Sierra. The combination of
river and glacier erosion exposed the uppermost portions of the plutons
emplaced millions of years before, leaving only a remnant of metamorphic
rock on top of some Sierra peaks.
Basin and Range
The Basin and Range is a large physiographic area covering most of Nevada,
part of eastern California, western Utah, and southeast Idaho. It lies in the
rainshadow of the Sierra Nevada, south of the Columbia Plateau and north of
the Mohave Desert, and is a mosaic of xeric basins, scattered mountains, and
salt flats. It is hotter and contains more and higher mountains than the
Columbia Plateau, with more perennial streams and ponderosa pine forest at
the higher elevations. Compared to the Mojave Desert, it is not as hot and is
more dominated by shrubland and less by grassland.
Columbia Plateau is an arid sagebrush steppe and
grassland surrounded on the north, west, and east by moister, predominantly
forested, mountainous ecological regions. It is an oddly shaped physiographic
area that covers portions of Washington, Oregon, Idaho, Nevada, and a small
piece of northeast California. It consists of arid tablelands, intermontane
basins, dissected lava plains, and widely scattered low mountains. There is a
more subtle transition to the Basin and Range to the south in which hotter
lowlands are dissected by isolated mountain ranges
Transverse Range (The Los Angeles Ranges)
Great Valley (San Joaquin Valley)
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. The Peninsular Ranges located to
the south cover the southwestern tip of the state. 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 San Bernardino. The highest point of the range is Mount San Gorgonio at
11,499 feet (3,505 m). The San Gabriel Mountains have Mount Wilson
observatory, where the redshift was discovered in the 1920s.
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. 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, and Sacramento are seaports.
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.
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.
This is a fertile area that extends 500 miles from the northwest to the
southeast. Farmland is located in this region. The San Joaquin and the
Sacramento, two of the state's largest river systems are located in the Central
Valley. To the east of the Central Valley is the Sierra Nevada region, a 400mile long area of massive granite rock. The highest point in the continental
United States, Mt. Whitney, with an elevation of 14,495 feet, is located here.
Mt. Shasta and Mt. Lassen, two volcanic peaks, lie to the north of the Sierra
Nevada. They are part of the Cascade Mountains.
The Central and Southern California Coast and Valleys covers the central and
southern coast of California, including the San Francisco Bay and extending
to the Mexican border. In the interior it includes the Central Valley and
foothills of the Sierra Nevada. Chaparral is the climax vegetation of areas
characterized by a Mediterranean climate. Various oaks and other evergreen
trees dominate many of the foothills. The Central Valley was a wetlandgrassland complex dissected by riparian strips. This is a diverse area with a
high degree of endemism.
Coastal Ranges
Great Basin Region
These Ranges in the north reach inland 20 to 30 miles extend
from the Klamath Mountains in the north south to Santa Barbara.
The Diablo and Santa Cruz Mountains are located in the Coastal
Ranges. Napa Valley separates these ranges. The legendary
Redwoods and the San Andreas Fault are located in the Coastal
Ranges. The San Andreas Fault enters California from the
Pacific Ocean near Port Arena and extends southeast into the
state. Earthquakes are caused by movement of the earth's crust
along this fault
The Great Basin Region is part of a larger
area that extends into Nevada and Oregon. In
northern California, it is a lava plateau. To the
south, it is an area of wastelands that include
the Mojave Desert and the Colorado Desert.
North America's lowest point, Death Valley,
282 feet below sea level, is located in the Great
Basin.
Southern Pacific Rainforests extends from the Pacific coastline
of Washington and Oregon inland to the crest of the Cascade
Mountains. It ends arbitrarily at the Canadian border, and also
includes the coastal ranges of northwestern California. Save for
coastal estuaries and some inland drier valleys (the Willamette
and the Puget Trough), the natural vegetation is coniferous
forest. There are six coniferous forest types, defined by elevation
and latitude, including the coastal Sitka spruce zone, lowelevation western hemlock/western red cedar, mid-elevation
Pacific silver fir zone, subalpine mountain hemlock, a mixedconifer zone in the Klamath/Siskiyou Mountains, and the
redwood forest of northwest California
Colorado Desert
To the east of the peninsular ranges lie the Colorado and Sonoran Deserts,
which extend into Arizona and Mexico.
The ground elevation is generally lower and in some areas was compressed
downward, therefore the eastern Coachella and Imperial Valleys north of the
U.S.-Mexican border are below sea level, the lowest community in the U.S.
is Calipatria, California at 160 feet (49 m) below sea level. The Sonoran
Desert receives a low and unevenly distributed amount of precipitation over
extensive plains and isolated mountains surrounding the northern end of the
Gulf of California. In the United States it is centered in southwest Arizona
and southeast California and extends south through most of Baja California
Norte and Sur and the western half of the state of Sonora. Vegetation is
sparse and differs from other American deserts by a greater dominance of
trees, including arborescent cacti such as the saguaro. Creosote is a common
and widely distributed shrub.
Mojave Desert
In the "Great American Desert" of the Southwest, the Mohave lies between
and is intermediate in nature between the Great Basin to the north and the
Sonoran Desert to the south and east. It is mostly in southeast California but
extends also into southern Nevada, northwest Arizona, a very small part of
southwest Utah, and lies in the rain shadow of the Southern California Ranges
to the west. Its most prominent features are broad, sparsely vegetated plains.
However, it also includes dry lakes, sharply rising buttes and relatively small
mountain ranges, and its eastern portion is cut through by the Colorado River.
It is generally a higher elevation desert than the Sonoran, although elevation
descends to -300 m in Death Valley. Low precipitation, most falling in
winter, with low winter and high summer temperatures are characteristic. The
Great Basin Region is part of a larger area that extends into Nevada and
Oregon. In northern California, it is a lava plateau. To the south, it is an area
of wastelands that include the Mojave Desert and the Colorado Desert. North
America's lowest point, Death Valley, 282 feet below sea level, is located in
the Great Basin.