|
Exploring the beautiful nature of California
California Nature: Lakes
|
|
Lakes are not permanent. Over time all lakes
will shrink and disappear. Some will dry out, others will fill
up with sediment. This doesn't happen overnight. It can take
thousands and thousands of years! Lakes can range in size from
small to large. They can be very deep or relatively shallow.
Lakes that have depths of less than six or seven feet and plant
life on the bottom, are often called ponds. There are no rooted
plants at the bottom of lakes, because the water is too deep for
sunlight to reach. Lakes get their water from precipitation,
from rivers and streams and from underground water.
Natural lakes can form by various processes. Although many of
these processes occurred in the geologic past, lakes continue to
form and to be destroyed. Many lakes have formed as a result of tectonic movements of the Earth's crust.
|
 |
Lakes can be divided into three zones based on how much light
penetrates the water. The littoral zone
stretches across the lake surface and penetrates to where light
can reach the lake bottom. The photic zone is
the middle zone. Some sunlight reaches this zone and some plants
grow here. The last zone is the aphotic zone.
No sunlight reaches this zone, so there are no plants.
A pluvial lake is a lake that experiences significant increase
in depth and extent as a result of increased precipitation and
reduced evaporation. These type of lakes formed from rainwater
falling into a landlocked basin during a glacial period marked
by greater precipitation than is found in the region in prior or
subsequent periods.
Lake Lahontan is a pluvial lake that covered nearly all of
northwestern Nevada as well as parts of northeastern California
and southern Oregon. At its peak about 12,700 years ago it
covered approximately 8,500 square miles
|
|
|
A caldera is a large, usually
circular depression. A caldera forms when the
top of a volcano collapses and becomes
wedged into the nearly empty magma chamber. The large, sunken crater can become
filled with water, forming scenic lakes and landscapes.
Calderas
can be up to 50 km in diameter. Volcanic eruptions that form
calderas are often the largest eruptions on Earth. Crater Lake Caldera is
597 meters deep. The lake partly fills a nearly
1,220 meter deep caldera that was formed around
6,900 years ago by the collapse of the volcano
Mount Mazama.
The Earth is constantly shifting and moving. Lots of the world's
lakes formed because of changes in the land caused by
earthquakes. Earthquakes sometimes leave basins in the Earth
that become lakes. Many lakes in the western United States, like
Lake Tahoe on the California-Nevada border, were formed in
depressions formed by earthquakes.
|
 |
California has, at the present time, more than 2,000 lakes, most
of which are man-made. There are 2,440 dams within California
and 1,013 small dams not under the jurisdiction of the state,
mostly for agricultural use. Most of the state's natural lakes
have been messed with in one way or another. There are 200 major
lakes and reservoirs in California. Some of the biggest lakes in
California exist no more!
Owens Lake was drained by the City of Los Angeles. This lake was
once one of the largest in California, at 112 square miles. In
1872, it was crossed by steamboat. Owens Lakebed is now
the single most important source of air pollution in the United
States, caused by dust from winds howling across its salty bed.
Mono Lake, on the east side of the Sierra near Yosemite, was
almost destroyed by LA in recent times for yet more water. But
some hard-working environmentalists managed to save what is left
of it. Mono Lake is now on a long, slow road to recovery. |
|
|
Located in California's spectacular Eastern Sierra, Mono Lake is
an oasis in the dry Great Basin and a vital habitat for millions
of migratory and nesting birds. One of the oldest lakes in the
western hemisphere, Mono Lake is hauntingly beautiful,
reflecting the snow-capped Sierra Nevada in its shimmering blue
waters. An immense inland sea, the 70 square-mile lake fills a
natural basin, 700 square-miles in size.
In the western part of the state is Clear Lake, the largest freshwater
lake by area entirely in California. Though Lake Tahoe is
larger, it is divided by the California/Nevada border.
One of the world's largest inland seas and lowest spots on earth
at -227 below sea level, Salton Sea was re-created in 1905 when
high spring flooding on the Colorado River crashed the canal
gates leading into the developing Imperial Valley. For the next
18 months the entire volume of the Colorado River rushed
downward into the Salton Trough. By the time engineers were
finally able to stop the breaching water in 1907, the Salton Sea
had been born at 45 miles long and 20 miles wide, equaling about
130 miles of shoreline.
|
|