The
geology of California is the result of volcanic and tectonic
activity. California’s mountains were shaped by glaciers during
the Ice Age, and they were then modified by erosion in the form of
wind and rain.
California’s coastline is reshaped every day by the pounding waves
of the Pacific Ocean.
It is wealthy in natural resources, including:
·
the rich soil of the
Central Valley,
·
gold in the Sierra
Nevada, and
·
oil off the coast and
throughout the state.
But
perhaps nothing says "California" more than its Coastal
Mountains.
The
Coastal Mountains
http://ceres.ca.gov/ceres/calweb/coastal/mountains.html
 California's
Coastal Mountains extend for 800 miles from Del Norte County in the
north to the Mexican border. Except for a break at the Golden Gate
Bridge, they form a continuous series of ranges and valleys. These
ranges and valleys separate the coast from the Central Valley and
the deserts of the interior.
The ranges form a mountain barrier that has a profound effect on
California's climate. Storms from the Pacific bring rain to the
mountains' western slopes, while the eastern slopes remain
relatively dry. The wet western weather supports the growth of
evergreen trees for the timber industry in the north, and the
cooling fogs support agriculture (grapes, fruit, nuts and
cool-weather vegetables) in the south from San Mateo County to San
Diego.
The geological history of the
Coastal Mountains began about 250 million years ago. That's when the
North American Plate and the Pacific Plate collided head-on. This
caused the Earth to push upward.
The upward push continued until about 30 million years ago when the
movement of the two plates changed from head-on collision to lateral
slippage. One result was that the San Andreas Fault was formed,
which is a strike-slip fault that causes many earthquakes.
Another result of the upward push was the folding of the sea floor
along the margin of the North American Plate. This folding created
California' s Transverse (Los Angeles) Ranges, which are composed of
crushed, crumpled and folded sea floor sediments.
Regions of California
http://www.beachcalifornia.com/california-regions.html
California is the third largest state in the Union, behind Alaska
and Texas. It covers 163,707 square miles, 7,734 of which are
covered by water.
The topography of California is divided into eight primary
regions:
- The
Klamath Mountains,
in the northwest corner are lush forest-covered ranges
separated by deep valleys. Some of the Klamath Mountains
rise as high as 8000 feet above sea level.
|
- The Coastal Range is
described above.
|
- The Sierra Nevada
is a mountain range that runs 430 miles from north to south,
and rises to over 14,000 feet high. Mt. Whitney is part of
the
Sierras. At 14,494 feet, it is the highest peak in the
United States south of Alaska. Over thousands of years,
mountain streams and glaciers have cut deep valleys into the
western part of this region. Yosemite is one of the most
famous of these valleys.
|
- The
Central Valley, which lies between the Coastal Range
and the Sierra Nevada, is sometimes called the Great Valley
and is about 450
miles long. It is a broad, fertile plain and is the most
important agricultural area west of the Rocky Mountains.
About 3/5 of California's productive farmland is located in
this region.
|
-
The
Cascade Mountains
extend north from the Sierras. Unlike other California
mountains, the Cascades were formed by volcanoes. One
volcano, Mt. Lassen, is still classified as "active."
Another, Mt. Shasta, is thought to be no longer active,
although some geologists disagree.
|
|
contains
the southeastern deserts of California. This is part of a
large region (a geographical province) that extends into
Nevada, Oregon and other states. In the north, much of it is a
lava plateau that
was formed thousands of years ago by lava flowing out
of cracks in the Earth's surface. In the south, a good deal of
the Basin and Range Region is wasteland that includes the
Mojave Desert, which is separated from the Central Valley by
the Transverse Ranges. Death Valley is also in this region and
is one of the most inhospitable places on earth. Irrigation,
however, has turned parts of this region, namely the Imperial
and Coachella Valleys, into successful farmland.
|
-
The
Los Angeles Ranges
lie between Santa Barbara and San Diego counties, and is a
group of small mountain ranges that extends east to west.
Because of this east-west orientation, they are sometimes
also called the Transverse Ranges.
|
|
|
California's geology, and
geography, is amazingly diverse. Mt. Whitney and Death Valley are
only 85 miles apart, and there is nothing more spectacular than the
sandy beaches of Southern California.
To learn more about one of the most amazing states in the Union,
explore any of the Links at the end of this Instruction.
Experiments for Home and
Classroom
In Instruction 1-2, an experiment
with hard-boiled eggs was used to demonstrate various types of fault
boundaries, including the transform boundary of the San Andreas
Fault. This fault is one of California's, and the world's, most
famous faults and is responsible for a number of serious
earthquakes. A picture of the San Andreas Fault is shown at the
beginning of this Instruction. This experiment is from the
California Geological Survey. Click: http://www.consrv.ca.gov/cgs/information/kids_geozone/egg_tectonics.htm.
Like
landscapes everywhere, California's geography changes constantly.
Here are several geology experiments that explain why. Go to
"Do Rocks Last Forever?" at:
http://www.consrv.ca.gov/cgs/information/kids_geozone/do_rocks_last_forever.htm
Reading List:
From the California Dept.
of Education http://www.cde.ca.gov/ci/sc/ll/
|
for Students, Parents and Teachers
