[Fig. 41] Visitors can see one of the oldest lakes in North America just east of Yosemite National Park. Mono Lake, an alkaline body of water with curious mineral formations called tufa, offers bird-watching, swimming in briny water, walks along volcanoes that are still rumbling deep in the earth, canoeing, boating, and dramatic views of the high Sierra.
In 1984, Congress protected 40,000-acre Mono Lake and its ecosystems by designating it the Mono Basin National Forest Scenic Area. California, three years earlier, granted protections for the tufa mineral columns around the lake. The state designated the area as the Mono Lake Tufa State Reserve.
Mono Lake is a terminal lake, a depression in the earth where streams enter but do not leave. It is at the foot of Lee Vining Canyon, which descends from the Yosemite park line east of Lee Vining. The lake is the destination for several streams that have carried water and sediment into the lake bed since the Ice Age.
The origins of the lake bed can be traced back about 10 million years to when Mono Basin's floor began slipping downward as the Eastern Sierra lifted and tilted west along faults beneath the earth's surface. The lake probably began holding water about 1 million years ago.
To check the age of Mono Lake in the early part of the twentieth century, a well was drilled 1,400 feet deep on Paoha Island, one of Mono Lake's two volcanic islands. It struck light pink rock known as Bishop Tuft, which came from a massive volcanic blast more than 700,000 years ago. There were no saline layers in between, indicating the lake had not dried up for at least 700,000 years.
When the massive faulting began along the Eastern Sierra about 10 million years ago, a vast redwood forest covered the area. As the Sierra rose in the west, it began to block storms coming from the Pacific Ocean.
A "rain shadow" developed, meaning the west side of the Sierra absorbed most of the moisture from the storms and the east side became arid. The redwood forest changed to vegetation more tolerant of dry conditions, such as Indian manzanita (Arctostaphylos mewukka), pinion pine (Pinus monophylla), and, eventually, sagebrush (Artemesia tridentata).
The dry conditions created this sparse, desert vegetation, which enhances
the stark, almost moonscape appearance around Mono Lake. John Muir described
"a country of wonderful contrasts." These contrasts between the desert and the high Sierra in the background have captured photographers' imaginations for many decades.
The two volcanic islands are particularly interesting for photographers and boaters, who like to paddle out and explore them. They are Negit Island and Paoha Island. Paoha is the more eerie of the two. Erupting into existence about three centuries ago, Paoha has little vegetation. On its north and south ends, cinder cones mark the place where the island began with lava flows. Negit is about 1,700 years old. It is darker and much smaller than Paoha.
The lake contains some of the saltiest water in California or anywhere else. It comes from natural salinity left by the ocean many millions of years ago. As streams carry it into Mono Lake, the salt content becomes more concentrated. It is almost three times as salty as the Pacific Ocean and 1,000 times saltier than Lake Tahoe. Mono Lake contains about 280 million tons of dissolved salts.
As a result of the salts, it is virtually impossible to sink in Mono Lake. The south shore at Navy Beach attracts a lot of swimmers. A word of caution: Don't open your eyes in this water. It will sting.
Chemically, the lake's water contains a lot of chlorides, carbonates, and sulfates, which are carried in from the mountain streams around the lake. There are few places on earth where this combination exists, and it helps to create tufa, the strange, jagged columns sticking out of the water and scattered about the periphery of the lake.
Tufa towers have been described as fossilized underwater springs. They form from fresh underwater springs that contain calcium carbonate, a mineral in limestone. The tufa form in a chemical process occurring when the calcium in the spring water encounters the brine in Mono Lake. They combine and create a solid, composed of calcite or aragonite.
The process goes on in the surrounding beach areas as well as the lake bottom. Ground water seeps into the sandy areas to combine with the briny water, and tufa towers begin to grow a few millimeters annually.
Within such briny, mineral-laden water, one might suspect there would be little life. Indeed, there are no fish or vascular plants. About eight invertebrate species are visible to the eye in Mono Lake, and there are about 25 microscopic species.
Because there are no fish to feed on them, the hardy creatures that survive in this water have few predators. The alkali fly (Ephydra hians) and the Mono brine shrimp (Artemia monica) are the most noticeable forms of life. They are everywhere in great numbers. They are considered "osmoregulators," meaning they have evolved the ability to pump unwanted substances out of their bodies.
The Mono brine shrimp cannot live anywhere else on earth. They are not even like other brine shrimp. They produce cysts, not eggs, and the cysts hatch in warmer water. Biologists have found 50,000 of them in a single cubic yard of Mono Lake water.
The alkali flies are also abundant at Mono Lake, and they are eaten in great numbers by shorebirds in the area. Thousands of the flies, which usually have no interest in even landing on humans, can be found in each square foot along the shore.
The Wilson phalarope (Steganopus tricolor), the eared grebe (Podiceps caspicus), and the California gull (Larus californicus), along with many other kinds of birds, will fly hundreds, even thousands of miles to dine for a season at Mono Lake. In the fall, for instance, more than 700,000 grebes fly to Mono Lake from breeding grounds as far away as western Canada. They feast on the insect life, and they prefer the Mono Lake winter climate to Canada's.
These huge gatherings of birds were impacted in the mid-twentieth century when Los Angeles began tapping into the Mono Lake creek system for water. By 1970, Los Angeles was diverting water from Lee Vining, Walker, Parker, and Rush creeks around Mono Lake. By 1981, Mono Lake had dropped 45 vertical feet and salinity had doubled. Negit Island had become a peninsula, and predators were decimating the bird population.
After an environmental lawsuit was filed in the late 1980s, the issue of Mono Lake's decline came before the California Water Resources Control Board, which determined in 1994 that the lake and ecosystem had been damaged by water diversions. An advocacy group, the Mono Lake Committee, and Los Angeles forged a settlement calling for the restoration of the ecosystem. The water diversions are no longer taking place.
Scientists believe it will take several decades for the lake to recover. But the lake already has risen more than 12 feet, and scientists have been encouraged by the rebounding ecosystem.
[Fig. 41(2)] People bring their large lenses, cameras, and binoculars to this vista point to enjoy the sweeping view. This is the western edge of the geological domain called the Great Basin, which stretches hundreds of miles to Nevada and Utah. From this point, Mono Lake to the southeast is 1,000 feet below. It is an awesome depression with streams draining into it. Keep looking southeast on a clear day to see the White Mountains beyond Mono Lake. White Mountain Peak juts out at 14,246 feet. Just west of the White Mountains, you will see Glass Mountain, an 11,123-foot volcano. It erupted almost 1 million years ago.
Farther west, the Mono Craters are visible. And, the Sierra Nevada stands high in the west with jagged granite peaks etched into the skyline. Mono Lake is one of the Great Basin's many terminal lakes, which do not allow water to drain into the ocean. The Great Salt Lake is another well-known terminal lake.
[Fig. 41(3)] The view from Panum Crater, near the southern shore of Mono Lake, takes in the Mono Craters, Koip Peak, Mount Gibbs, Mount Lewis, and Mount Dana. Looking east, between Gibbs and Lewis, visitors can see two lateral moraines near the mouth of Bloody Canyon.
Panum Crater is a rounded pumice feature, one of the latest of the Mono Craters. It formed as magma moved up from the earth and worked its way through the underground aquifer. The hot magma created pressure in the aquifer and caused it to open up with a violent explosion. The explosion made the crater. For bird watchers, it is interesting to note several species in the area, including green-winged teal (Anas crecca), Canada goose (Branta canadensis), American avocet (Recurvirostra americana), and western sandpiper (Calidris mauri).
[Fig. 41(4)] Walk through the tufa towers along the south shore of Mono Lake and see how eerie they are up close. But don't climb on them or take any part of them as a souvenir. State law protects the tufa.
The towers are created by the combination of the salty lake water and freshwater springs from beneath the lake and beach. The main ingredients are calcium from the fresh water and carbonates from the tufa. The chemical result is the same as limestone. As you walk along the water's edge, stick your toes in and experience how slick it is. If you taste Mono Lake water, it is briny and bitter.
The beach is filled with alkali flies (Ephydra hians)swarms of them. But they are not interested in humans. They will flee as people approach. They may seem a bit disgusting, but Native Americans have long considered them a delicacy.
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