Allison,
The Salton Sea existed before in the form of several areal lakes during the Pleistocene, but the best known is ancient Lake Cahuilla, which was created when the Colorado River's flow was diverted naturally during a time prior to Spanish presence in the region. Lake Cahuilla was over 3 times as large as the present Salton Sea and inundated areas that include the cities of Indio and Mexicali. When the Colorado River shifted once more, the lake was cut off from any form of inflowing fresh water, as it exists in a basin between two mountain ranges (the Chocolate Mountains to the east and the Santa Rosas to the west). In 1905, the Salton gained more fresh water thanks to a plan to use the Colorado River's flow to irrigate the Salton Basin, but the project ended in disaster thanks to flooding. The Colorado began to periodically flood the Salton Sea, which led to the construction of Hoover Dam. And that is why there will be no more drainage into the Salton, except for agricultural runoff.
I have a preserved piece of tufa from the shoreline of Lake Cahuilla, as my husband and I used to walk along the edges of that former shoreline. There is even a huge display near the northwestern edge of the sea called Travertine Rock (which has been terribly marked with graffiti). The biodiversity there is amazing, from plants to reptiles to birds that have evolved over the years and have adapted successfully to their environment. In turn, the Salton has become an important waterway for a vast number of migrating birds, who depend on the water for food and the area for a place to raise their young. The run off from man's agricultural presence in the area is causing the salinity to increase, as well as the constant rise in pH in the sea. This is why the fight to save the Salton is so important.
In the spring, there is a dormant volcano near Obsidian Butte (another plug) that abuts the sea and it is a major site for reproduction for these birds and for a couple of months, is closed off to the public.
Hope this info helps,
Lin
On Wed, Jul 31, 2013 at 9:50 AM, Allison Maricelli-Loukanis <allison.ann@att.net> wrote:
I am confused... this article says that the Sea was formed by the rupture of an irrigation canal. But when I googled Salton Sea, that Wikipedia article said the sea is NOT a man made lake. So... how does one define the Sea? There is an awful lot of biodiversity for something that only formed in 1910 or 1911..forget which. Allison
From: Lin Kerns <linkerns@gmail.com>
To: Geology2 <geology2@yahoogroups.com>
Sent: Wednesday, July 31, 2013 8:33 AM
Subject: [Geology2] The Salton Trough
My favorite place on earth (so far):
acquired June 21, 2013 download large image (528 KB, JPEG, 1440x960)The Imperial and Coachella Valleys of southern California, and the corresponding Mexicali Valley and Colorado River Delta in Mexico, are part of the Salton Trough. This large geologic structure, known to geologists as a graben or rift valley, extends into the Gulf of California. The trough is a geologically complex zone formed by the interaction of the San Andreas transform fault system—which is, broadly speaking, moving southern California towards Alaska—and the northward motion of the Gulf of California segment of the East Pacific Rise, which continues to widen the Gulf of California by seafloor spreading.Sediments deposited by the Colorado River have been filling the northern rift valley (the Salton Trough) for several million years, excluding the waters of the Gulf of California, and providing a fertile environment for the development of extensive, irrigation-aided agriculture in the region (visible as green and yellow-brown fields at image center). The Salton Sea, a favorite landmark of astronauts in low-earth orbit, was formed by the rupture of an irrigation canal in 1905 and today is sustained by agricultural runoff water.A wide array of landforms and land uses in the Salton Trough are visible from space. In addition to the agricultural fields and Salton Sea, several metropolitan areas are visible, including Yuma, Arizona; Mexicali, Mexico; and the San Diego-Tijuana conurbation on the Pacific Coast (image left). The 72-kilometer-long Algodones Dunefield also is visible at image top right.Astronaut photograph ISS036-E-11034 was acquired on June 21, 2013, with a Nikon D3S digital camera using a 50 millimeter lens, and is provided by the ISS Crew Earth Observations experiment and Image Science & Analysis Laboratory, Johnson Space Center. The image was taken by the Expedition 36 crew. It has been cropped and enhanced to improve contrast, and lens artifacts have been removed. The International Space Station Program supports the laboratory as part of the ISS National Lab to help astronauts take pictures of Earth that will be of the greatest value to scientists and the public, and to make those images freely available on the Internet. Additional images taken by astronauts and cosmonauts can be viewed at the NASA/JSC Gateway to Astronaut Photography of Earth. Caption by William L. Stefanov, Jacobs/JETS at NASA-JSC.
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