CALIFORNIA GEOGRAPHY
LANDFORM PROVINCES
VICKI DRAKE
EARTH SCIENCE DEPARTMENT
SANTA MONICA COLLEGE
I. Geomorphic/geographic provinces represent natural units within which boundaries of landforms are consistent with
those of the biological communities.
A. The shape of the Earth influences climate
B. Climate influences the distribution of plants and animals
II. The tectonic forces that created California also created the landform diversity found in California.
Pacific- facing mountain ranges A. Granitic Peninsular Ranges
B. East-west Transverse Ranges (a mixture of sedimentary, metamorphic and igneous rock)
C. Sedimentary Coastal Ranges - lifted from the shallow sea bottom
D. Klamath Mountains
Mountains of the Interior
A. Sierra Nevada - residual sedimentary/metamorphic - mainly granitic and
severely glaciated
B. Southern Cascades - Volcanics
C. Great Basin Mountains - up-faulted ranges due to extensional forces
Great Valleys
A. Death Valley - Down-faulted, below sea-level portion of the Great Basin
B. Southeastern Deserts - more of the Great Basin
1. Mojave Desert - slowly being squeezed by two great faults
C. The Central Valley - alluvium-filled valley in the center of California between Coastal Ranges and Sierra Nevada
Plateaus
A. Modoc Plateau - part of the volcanic tablelands (which include the Columbia Basalt Plateau)
What are some of the resources to be found in the various geographic provinces?
1. Oil - trapped in sedimentary structures of Coast Ranges and offshore
2. Gold - in the Sierra Nevada
a) Bedrock
b) Streams
3. Water - our most precious resource!
a. Western portion of mountains capture and hold moisture from
Pacific air as it flows western to east across the mountain ranges.
b. Areas downwind (leeward) of the Pacific air tend to be very dry
creating a condition of “Rain Shadow Deserts”
4. Soil - the richness of the soils in the interior Central Valley provide
thousands and thousands of square miles of very productive farmland.
5. Incredible scenery - which brings thousands and thousands of tourists
to California each year
Peninsular Range Province - massive western-dipping granitic fault block
A. The southernmost coastal landforms - so named because they form the northern end of the long peninsular AKA Baja
California
B. Area is West of San Andreas Fault - 25 million5 million ya this was part of mainland Mexico - there was no Gulf of
California (Cortez).
C. Area has been “dragged” 200 miles (320 km) north along the San Andreas Fault - opening of the Gulf of California.
Formed the basin known as “The Colorado Desert” or “Salton Trough” a Rain Shadow Desert, lying leeward of
Peninsular Ranges.
Interior Highlands
A. Highest points include Mt. San Jacinto (11,000 feet)
1. Not high enough, however, to be “alpine” - receives some snow...but not considered in the “skiing “ - snow
doesn’t stay long enough
2. Idyllwild (sw edge of Mt. San Jacinto park) an “alpine” settlement as mountains rise up from desert valley floors
3. Julian and Warner Springs - provide a “semi alpine” setting at high altitudes - and help from winter snows.
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B. Agriculture is not very extensive in this area...better in San Jacinto Basin valley floors to the west 1. better soils
2. longer growing seasons
(Fallbrook near San Diego, to Escondido, for example)
2. Riverside County - avocados, field crops, viticulture, citrus crops
Hemet, Perris, Temecula - began as agricultural towns
Coastal Features
A. Marine terraces tell of older times when the sea levels rose and fell with various Ice Ages.
B. Mission Valley - newest and most modern area for hotels, shopping centers, residences...Urbanization has arrived!
C. First mission settlement - San Diego de Alcala
D. San Diego is the second largest city in the state! - rapidly approaching the title of “Conurbation” - meaning an the
coalescing of several urban areas into one large urban area
E. San Diego Harbor - mainly used by military - is one of the few deep-water harbors in the state - although still not as
used as could be
F. Coastline includes Orange County (Huntington Beach, Newport-Irvine, Laguna, Laguna-Niguel,
1. Wide sandy beaches beckoned the people to put up houses,
condominiums, etc.
2. Bedroom communities
G. Coastline is not stable though - the terrace landscape is prone to landslides and erosion
H. Pressing problems
1. Eroding beaches as rivers are “channelized” for flood prevention and beach-making materials are hindered
from reaching the beach
2. Putting up jetties, sea walls, groins - to protect homes from wave assaults undermines and removes beach
sand
3. Normal removal of sand into submarine canyons does not have the counterpart of sands brought in via
rivers, etc.
Los Angeles Basin
A. The “South Coast” portion of the Peninsular Ranges, which also includes Santa Monica Bay * Basin, Palos Verdes
Peninsula, Long Beach.
B. Streams (Los Angeles, Santa Ana, Ballona Creek, and San Gabriel) did provide beach-making materials prior to
channelization
C. Most of this basin is sediment-fill to a depth of ~ 31,000 feet (material eroded from the mountains ringing the basin
and transported to the valleys via the aforementioned rivers/creeks.
D. Riddle with faults (both known and unknown)
1. Newport-Inglewood - most well known responsible for uplifting the Dominguez Hills, Baldwin Hills and
Palos Verdes Peninsular
E. Petroleum found beneath sedimentary soils of Long Beach and offshore
The Islands
A. Santa Catalina, San Clemente, Santa Barbara, San Nicolas
B. Part of the Peninsular Ranges as mountains sitting on a continental shelf extending to sea
C. Highest elevations ~ 2000 feet above sea level.
1. San Clemente sits on a fault as the Eastern portion is lifted up and the Western side has many marine
terraces.
D. Any animals found today were most likely brought over either by Native Americans who lived in, on and among the
islands. Or the animals were brought over by “Europeans” who lived there....i.e. white man”
Transverse Range Province - granitic - metamorphic -similar in age and
composition to Sierras
A. East-west trending range - rotated some millions of years ago
B. Include: Santa Monica Mountains, San Gabriel Mountains, San Bernardino Mountains, Santa Susanas, Hollywood
Hills, and Santa Ynez Mountains
C. Some of the oldest rocks (1.5 billion years) are found here.
D. The 3rd highest peak in California is Mount San Antonio (Mount Baldy) at 10,064 feet in San Gabriels
1. Mount San Gorgonio at 11,502 is the highest peak in southern California in the San Bernardinos separated from the San Gabriels by San Andreas Fault
2. Folding and faulting along San Andreas (and other faults) have led to formation of the steep canyons making firefighting almost impossible without helicopters/super scoopers
E. Vegetation type (even at elevation) is more chaparral community plants even with adequate precipitation - the
evaporation rate is so high, many water-loving plants can’t survive.
F. Dry chaparral - known for its combustibility - makes this a prime candidate for wildfires
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G. Glaciation scars are missing from this landscape and the lack of plentiful moisture (in terms of rain) make these very
steep mountains, with gravity the main source of erosion.
Onshore
A. Less densely settled - more true rugged wilderness area
B. Agriculture found its way into the San Fernando, San Gabriel Valleys, and Oxnard Plains.
C. Residential growth today pushing out the Farms
D. Mountain communities take advantage of winter storms laden with moisture and make skiing a popular late
winter/.early spring past time.
E. Mountains also act to “block” any superheated air from the Mojave...but also appear to be the dividing line between
north/southern California (actually Bakersfield is..)
F. Mountains are granitic and as such have helped put the “bend” in the San Andreas Fault, as they (mountains) help
deflect the Pacific Plate
Offshore
1. Islands are extension of the Transverse Ranges actually...may be part of the original Santa Monica Mountains..
connected by a land bridge (no longer there)
2. Santa Cruz, Santa Rosa, San Miguel, and Anacapa protected by states and federals
Coast Range Provinces
A. Extend over 500 miles from near the Oregon border to Santa Barbara
B. Rise to an average of 6000 feet in elevation from the ocean.
C. Ridges and valleys created by folding/faulting
D. Rivers flow northward from origin to Pacific Ocean
E. Mainly consist of Ocean Sediment - in various stages of alteration Serpentine (Serpentinite) - a green waxy rock is
the state rock found in the Franciscan Formation (names for San Francisco) Serpentine breaks down to form a soil that
support a unique assortment of plant species.
F. Southern portion of range more granitic - possibly formed at same time as Sierras
Northern Faults
A. Bounded by faults - movements began ~ 150 million ybp...possibly ending
about 500 mya. These faults caused the folding and faulting of Franciscan Formation
Coastal areas
A. Western side of Coast Ranges favored with ocean fog, mist and clouds with precipitation - think Big Sur - Giant
Redwoods (near Eureka)
1. Fog Drip becomes an important source of moisture for the vegetation
B. A few varieties of Pine found along the Coast as well - fog drip important as well.
C. Chaparral dominates south-facing steep slopes
D. North=facing slopes - evergreen oak woodland
E. Coastal terraces indicate changes in sea level
Valley Settlement
A. Coastal Plains and embayments offered places for civilization to settle.
B. San Francisco Bay - one of the few deep, protected and large embayments in the state - became the “Hot Spot” of
the West Coast
1. Fresh river water from Sacramento and fresh tidal waters kept the Bay clean, clear and exceptionally cold
(Alcatraz Island).
C. Other coastal plains developed into Oakland - Vallejo , etc.
D. More rural to south of San Francisco with economies more dominated by farming, dairying, and lumbering than by
Finance Centers
E. Cities include - San Luis Obispo, Santa Maria, Pismo Beach
F. Region of cattle ranches - as beef is a major industry in California
G. Many interior valleys converted into agriculture and viticulture
1. in southern valleys: corn , beets, and garden crops
2. northern valleys - wine grapes (Napa Valley)
3. Salinas is the lettuce capital of the world
Landlocked Counties
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A. Interiors include oak woodlands (areas with well-distributed oak trees and open grasslands)
B. Oil reserves found in the sedimentary rocks near Salinas and Cuyama Valleys
C. Reservoirs act to collect rainwater for settlers.
The Klamath Mountains Province
A. Northwestern most mountains - rocky upland with elevations of 5000-7000 feet
B. River systems have cut steep V-shaped canyons as heavy precipitation assures year- round flow (Klamath and
Trinity Rivers)
C. Siskiyou Mountains receive average ppt of ~ 140 inches per year.
D. Ample ppt and fog produce a dense forest cover including
1. Western Hemlock,
2. Sitka Spruce
3. Red Cedar
E. Very complex terrain
1. Uplift and extensive erosion over last 60 million years
2. Uplifted granitic and metamorphic rocks
3. A northern extension of Sierra Nevada - but separated by fault systems
4. Sculpted by glacier activity into crags, U-shaped valleys
5. Moraines (“dirt and rubble piles” left by retreating/advancing glaciers) dot valleys and streams
F. No cities, as such, in Klamath Mountains. National Recreational Areas, National Parks and Forests ,etc. dominate
the area. Small towns – but recreation and retirement are main focus of attraction.
The Southern Cascades and Modoc Plateau
A. Dominated by Mt Shasta (still considered an active and potentially dangerous volcano) at 14,200’.
1. Highest in a string of volcanoes (except for Mt. Rainier)
B. Overlooks part of Columbia Basalt Plateau - Modoc Plateau - a lava “tableland” created by lava welling up to the
surface through large fissure/cracks in the crust. “Extrusive” igneous rock cover
C. Area is still active with “fumaroles” (steam vents), hot springs, and boiling mud pots of Lassen Volcanic Park (Modoc
Plateau)
D. Some glacier scour and scars seen - evidence of late Pleistocene glaciations
E. Sparsely settled with exception of Yreka.
F. White settlers few - but still find remains of great Indian nations (less than 1,000 attempting to eke out an existence)
The Great Basin and Southeastern Deserts
A. Region of uplifted ranges and downdropped valleys owing to crustal extension as the Earth’s crust was thinned out
during subduction period
B. Area is generally arid to semi-arid.
1. Rivers, flowing in the rainy seasons, empty into the playas - which form temporary lakes until evaporation
2. Salt flats, gypsum, borax all formed here - commercial value in buildings, etc.
Death Valley
A. A downdropped alluvium filled basin that is surrounded by extremely high mountain ranges on the west and the east
Panamint Range - with Telescope Peak at 11,050’.; Funeral Mountains at 6,448’; White-Inyo Mountains at 14,426 ‘
(White Mountain Peak)
B. 140-mile valley - -288’ below sea level at lowest point - most arid point in continental United States
C. Site of ancient 600’ Lake Manly ~ late Pleistocene (~ 18,000-11,000 y ago)
1. Evidence: “bathtub ring” around mountains above valley floor
2. gravel bars - indicative of flowing and depositing water
3. wave-cut benches in lava flows
4 Tufa formation - formed during wetter times *
D. Faulting of Panamints to the west and Black Mountains to the east assure a continued down-dropping, along with
some later shifting going on by San Andreas Fault movement
E. Even during the Pleistocene - Death Valley still a Hot spot - Lake Manly filled, not because of excessive rainfall, but
rather from melting of glaciers in nearby mountains (evidence of glacier scour, scar, moraines. etc)
F. Order of filling of former lakes:
1. Owens Valley Lake, first 2. China Lake(gets overflow) 3. Searles (more overflow)
4. Panamint Lake (until depth of 1,000’)
5. Lake Manly (final resting spot for overflowing water)
G. Varied cultures passed through Death Valley
Lake Manly enjoyed an aboriginal culture settlement
Settled off and on (even after Lake dried up) by aborigines
Most recent were of Shoshone descent - nomadic tribes
Borate mining brought the White Man (and Chinese laborers)
Eagle Borax, Harmony Borax - mines that were worked during 1`880s.
Rail lines set up to transport Borate
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