Sierra Nevada, mountain range, western United States- a major range chiefly in California with a small portion in Nevada near Lake Tahoe, it extends from northwest to southwest for approximately 400 miles and varies in width from 40 to 80 miles. It is bounded on the north by a gap south of Lassen Peak and by the Cascade Range, and on the south by Tehachapi Pass. The tallest peak in the range is Mount Whitney (4,418m/ 14,494 ft above sea level). The western part of the southeastern portion of the range is called the High Sierra.
Climate: The western slope receives much more precipitation than the eastern slope because of a profound rain-shadow effect. Western slope ( Yosemite at 5500 ft elevation) receives around 75 inches of precipitation annually, eastern slope receives only 20 inches. Lower snow line is at about 3,000 ft. The snowfall and the resulting snow pack in the Sierra Nevada is the highest in the state. Most of Sierra precipitation falls during the months of January, February and March, and less than 3% during summer. Temperature also is influenced by elevation. The combination of lower temps and greater amounts of snowfall reduces the length of the growing season at higher elevations in the Alpine zone to about 6-8 weeks during the summer. Is due to adiabatic cooling. Air becomes drier at higher elevation. Adiabatic cooling also causes condensation and a loss of water vapor. Humans experience difficulty breathing at high elevations because air at higher elevations has a lowered capacity to hold water because it has fewer molecules per unit volume. Another effect of thin air at high elevations is an increase in Ultraviolet radiation. Ultraviolet light causes chromosome breakage and mutations in irradiated tissues that Alpine organisms have adapted to changes in the soil are also apparent. Soil tends to become coarser at the top of slopes and water holding capacity is greater at the bottom. Serpentine and Limestone also influence soil by a variety of parent rock types. At higher elevations the soil is mostly decomposed granite.
Geology: Sierra Nevada has three groups of rocks:
The largest sequence of metasediments and metavolcanics occurs along the western foothills on the northern flank of the range. The point of contact between the metamorphic rocks and the granites are important mineral bearing rocks. Gold and platinum may be presented.
Postbatholithic rocks of the Sierra are sedimentary and volcanic. Recent volcanism of the Sierra occurred along the eastern flank, where lava flows and cinder cones dot the landscape. A major field is found in the area from Mammoth Mountain to Mono Lake. Hot Creek in Mono County is an area of hot springs east of Mammoth Mountains. Expansion, cracking, weathering, and erosion have caused the dome shape so characteristic of granitic landforms which can be viewed eastward frpm Glacier Point, Yosemite National Park. Chemical weathering is the action of weak acids that can produce small pits on flat granite surfaces, in which organic debris and water may accumulate. As bacteria decompose the organic material excrete carbon dioxide, which combines with water to produce carbonic acid. This acid eats away at the rocks. Sierran granite has a lighter color due to weathering by ice and water rather than oxidation by sunlight.
The major force responsible for the appearance
of the Sierra is glaciation. It has carved and shaped the
terrain and removed most of the soil. During the Ice Age there were
many glaciers that covered most of the high country. To date there
are 60 to 70 glaciers of the Sierra Nevada date back to about 600
years ago. The largest is Palisades Glacier near Big Pine. Glaciers
occur when snow accumulates faster than it melts. When glaciers
retreat, it leaves behind a ridge of rubble known as a moraine.
Sliding of glaciers to make more room will cause a process that is
refer to as "eat" its way into the rock at its upper end and as a
result a basin with a circular cliff wall. This type of basin is
known as a cirque. Many lakes and meadows in the Sierra today lie in
Orrs Springs Scouts
The Konocti Krowd
There are three rock groups; batholithic, prebatholithic and postbatholithic. About 80 million years ago the uplifting of the batholithic granitic rock began. There was volcanic activity along the northern crest of the Sierra about 20 to 5 million years ago. "Prebatholithic rocks in the Sierra today are mostly metamorphic rocks that lie on the eastern and western flanks of the range north of the San Joaquin drainage. The largest sequence of metasediments and metavolcanics occurs along the western foothills on the northern flank of range. Presence of gold and platinum may occur when the metamorphic rocks and granites make contact. Gold was discovered in the gravel in the American River near Sutters Mill. A Tungsten processing mill near Bishop is among the largest in the United States. "Postbatholithic rocks of the Sierra are sedimentary and volcanic.
Mammoth Mountain is a quiescent volcano that formed about 370,000 years ago." It is 11,053 feet high. Recent earthquakes in the area indicate some activity. "In May 1980, four earthquakes within 48 hours, registering about 6 on the Richter scale, jolted Mammoth Lakes." (p. 80). Geologic processes composed mostly of granitics make up the appearance of the Sierra today. Mechanical weathering is the freezing of water or growth of roots. "Expansion, cracking, weathering and erosion have caused the dome shape so characteristic of granitic landforms." (p. 83). Glaciations are responsible for how the Sierra now looks. "During the Pleistocene, the Ice Age, there were many periods when glaciers covered large portions of the high country."(p. 85).
When son is built up quicker than it melts a glacier is formed. It is compressed by its own weight and become ice. "When a glacier retreats, it leaves behind a ridge of rubble known as a moraine." (p. 87) "The upper end of a glacier freezes into cracks and fissures, a process that causes more rocks to break off." (p. 87). Mt. Whitney and Mt. Langley both measuring more than 14,000 feet are said to be erosion surfaces that predate the glaciers. "Alternating phases of uplift and erosion formed other tablelands at later intervals."(p. 91).
Typically seedlings can grow from 6 inches to 2 feet per year. If the ground cover is more than an inch, seeds cant reach the good mineral soil. Once germination occurs and "for 600 to 700 years the trees retain a spire shape."(p. 122). The top branches reach the canopy of the forest about 250 feet from the ground. Old trees with rounded tops are often struck by lightening. They can survive with "different of damage to the crown."(p. 122). Branches that o catch on fire land on the ground then roll downhill. If it hits the trunk of another Sierra Redwood the fire may burn the bark and make it hollow. The uppermost branches begin to die from lack of water reaching its top.
Yellowstone National Park in Wyoming was established 1890, Kings Canyon 1940. John Muir and the Sierra Club have done a lot to preserve the Sierra Redwood forests. "Photochemical smog is having an influence on the composition of the Yellow Pine Forest."(p.123).
Animals of the Yellow Pine Forest
Amphibians-salamanders, toads, frogs are hidden in the ground cover, under rocks and logs. Reptiles &emdash; lizards and snakes, the lizard Gilberts skink, Eumeces gilberti, found in the foothills. Western skink, Eumeces skiltonianus, in the Kern Plateau. Alligator lizards in the Yellow Pine forest, the Northern Alligator Lizard, Elgaria coeralea, Southern Alligator Lizard, Elgaria multicarinata, in the southeastern Kern Plateau. The California Mountain Kingsnake and Rubber Boa are in the Yellow Pine forest rather than the foothills. Kingsnakes will eat other snakes, even rattlesnakes, also lizards. Rubber Boa eats insects, lizards, salamanders and small mammals.
Most birds migrate in the winter except the Stellers jay, the Darkeyed Junco, and the Mountain Chickadee. The Grosbeak family live at higher elevations. The western Tanayet and the American Robin, woodpeckers, and sparrows.
Western Gray squirrel, chickarees, mule deer, black bears, mountain lion.
Lodgepole Red Fir Forest
This is the snow forest of the Sierra Nevada. There is Mountain Hemlock, western White Pine, Sierra Junipers and Bush Chinquapin. "The deep shade of the Lodgepole-Red Fir Forest makes it difficult for understory plants in general. Some plants, however, have developed a strategy of deriving most if not all their nutrition not from photosynthesis but from decay of humus."(p. 145) There is Shinleaf or White-veined wintergreen, snow plants, Pinedrops, which look like tall skinny snow plants. Some call it a parasite because it has no root system or fungi. It draws nutrition from the mycorrhizae that are associated with adjacent plants. There are Coral roots and Phantom orchids.
There are flickers, Red Crossbills, Hermit Thrush, Sierra or Blue Grouse, hawks, owls, and Northern Goshawks.
There are squirrels, Chickarees, Chipmunks, and Martens, (a large weasel).
"Abundant water and cold-air drainage provide a cold, moist climate that is unique in California, where hot, dry summer dictate the nature of most communities."(p.153). A riparian community (woodland) is very productive where lots of food means lots of animals. "The zone where two communities overlap, called an ecotone, shares characteristics of both communities, and therefore is diverse."(p. 153). Riparian species are often wind-pollinated and wind-dispersed. California has 31 species of the willow family. At lower elevations the shrubs are taller and in the valleys, willows are trees. "A very interesting phenomenon associated with various species of willow is that they produce a plant toxin know as salicin, a name derived from the name of the genus, Salix. The chemical is similar in some ways to aspirin, or acetylsalicylic." (p. 155). There are Sycamores, white Alders, Water birch, and Big leaf Maples. "During the spring Pacific Dogwoods are most conspicuous when leafless branches become laden with white flowers up to 6 inches across. "The eastern variety often has reddish notches at the end of each bract, leading the story that dogwood was used to build Christs cross. Lest we forget, cross-shaped flowers with blood spots remind us of that event."(p159). There are Creek dogwoods or Red-osier Dogwoods, Western Azaleas, Manzanitas and Madrones. There are Flowering or Foothill Ashes, Oregon Ashes and Madrones occurring in the Northern Sierra Nevada, primarily between Butte and Calaveras Counties.
The Riparian woodland is home to Starlings, Cowbirds, Red-winged
Blackbirds, House Wren, American Dipper or Water Ouzel and