The Great Basin is the largest area of contiguous endorheic watersheds in North America. The region spans several physiographic divisions, biomes/ecoregions, and deserts, the term Great Basin is applied to hydrographic, floristic, physiographic and ethnographic geographic areas. The name was coined by John C. Frémont, based on information gleaned from Joseph R. Walker as well as his own travels, the hydrographic definition is the most commonly used, and is the only one with a definitive border. The other definitions yield not only different geographical boundaries of Great Basin regions, the Great Basin physiographic section is a geographic division of the Basin and Range Province defined by Nevin Fenneman in 1931. The United States Geological Survey adapted Fennemans scheme in their Physiographic division of the United States, the section is somewhat larger than the hydrographic definition. The culture area covers approximately 400,000 sq mi, or just less than twice the area of the hydrographic Great Basin, the hydrographic Great Basin is a 209,162 square miles area that drains internally.
All precipitation in the region evaporates, sinks underground or flows into lakes, as observed by Frémont, streams, or rivers find no outlet to either the Gulf of Mexico or the Pacific Ocean. The region is bounded by the Wasatch Mountains to the east, the Sierra Nevada and Cascade Ranges to the west, the south rim is less distinct. The Great Basin includes most of Nevada, half of Utah, substantial portions of Oregon and California and small areas of Idaho, the term Great Basin is slightly misleading, the region is actually made up of many small basins. The Great Salt Lake, Pyramid Lake, and the Humboldt Sink are a few of the drains in the Great Basin, the Salton Sink is another closed basin within the Great Basin. The Great Basin Divide separates the Great Basin from the watersheds draining to the Pacific Ocean, the southernmost portion of the Great Basin is the watershed area of the Laguna Salada. The Great Basins longest and largest river is the Bear River of 350 mi, Lake Tahoe, North Americas largest alpine lake, is part of the Great Basins central Lahontan subregion.
The hydrographic Great Basin contains multiple deserts and ecoregions, each with its own set of flora. The ecological boundaries and divisions in the Great Basin are unclear, the Great Basin overlaps four different deserts, portions of the hot Mojave and Colorado Deserts to the south, and the cold Great Basin and Oregon High Deserts in the north. The deserts can be distinguished by their plants, the Joshua tree and creosote bush occur in the hot deserts, the cold deserts are generally higher than the hot, and have their precipitation spread throughout the year. The climate and flora of the Great Basin is strongly dependent on elevation, as the elevation increases, because of this, forests occur at higher elevations. Utah juniper/single-leaf pinyon and mountain mahogany form open pinyon-juniper woodland on the slopes of most ranges, stands of limber pine and Great Basin bristlecone pine can be found in some of the higher ranges
Sequoia National Park
Sequoia National Park is a national park in the southern Sierra Nevada east of Visalia, California, in the United States. It was established on September 25,1890, the park is south of and contiguous with Kings Canyon National Park, the two are administered by the National Park Service together as the Sequoia and Kings Canyon National Parks. They were designated the UNESCO Sequoia-Kings Canyon Biosphere Reserve in 1976, the park is famous for its giant sequoia trees, including the General Sherman tree, the largest tree on Earth. The General Sherman tree grows in the Giant Forest, which five out of the ten largest trees in the world. The Giant Forest is connected by the Generals Highway to Kings Canyon National Parks General Grant Grove, the parks giant sequoia forests are part of 202,430 acres of old-growth forests shared by Sequoia and Kings Canyon National Parks. Indeed, the preserve a landscape that still resembles the southern Sierra Nevada before Euro-American settlement. Many park visitors enter Sequoia National Park through its entrance near the town of Three Rivers at Ash Mountain at 1,700 ft elevation.
The last California grizzly was killed in this park in 1922, the California Black Oak is a key transition species between the chaparral and higher elevation conifer forest. At higher elevations in the front country, between 5,500 and 9,000 feet in elevation, the landscape becomes montane forest-dominated coniferous belt, found here are Ponderosa, Jeffrey and lodgepole pine trees, as well as abundant white and red fir. Found here too are the giant sequoia trees, the most massive living single-stem trees on earth, between the trees and summer snowmelts sometimes fan out to form lush, though delicate, meadows. In this region, visitors often see deer, Douglas squirrels, and American black bears. There are plans to reintroduce the bighorn sheep to this park, the vast majority of the park is roadless wilderness, no road crosses the Sierra Nevada within the parks boundaries. 84 percent of Sequoia and Kings Canyon National Parks is designated wilderness and is only by foot or by horseback. Sequoias backcountry offers a vast expanse of high-alpine wonders, covering the highest-elevation region of the High Sierra, the backcountry includes Mount Whitney on the eastern border of the park, accessible from the Giant Forest via the High Sierra Trail.
On the floor of canyon, at least two days hike from the nearest road, is the Kern Canyon hot spring, a popular resting point for weary backpackers. From the floor of Kern Canyon, the trail ascends again over 8,000 ft to the summit of Mount Whitney, in the summertime, Native Americans would travel over the high mountain passes to trade with tribes to the East. By the time the first European settlers arrived in the area, smallpox had spread to the region. The first European settler to homestead in the area was Hale Tharp, Tharp allowed his cattle to graze the meadow, but at the same time had a respect for the grandeur of the forest and led early battles against logging in the area
State parks are parks or other protected areas managed at the sub-national level within those nations which use state as a political subdivision. State parks are established by a state to preserve a location on account of its natural beauty, historic interest. There are state parks under the administration of the government of each U. S. state, some of the Mexican states, the term is used in the Australian state of Victoria. The equivalent term used in Canada, South Africa, similar systems of local government maintained parks exist in other countries, but the terminology varies. State parks are thus similar to parks, but under state rather than federal administration. Similarly, local government entities below state level may maintain parks, in general, state parks are smaller than national parks, with a few exceptions such as the Adirondack Park in New York and Anza-Borrego Desert State Park in California. As of 2014, there were 10,234 state park units in the United States, there are some 739 million annual visits to the countrys state parks.
The NASPD further counts over 43,000 miles of trail,217,367 campsites, many states include designations beyond state park in their state parks systems. Other designations might be state recreation areas, state beaches, some state park systems include long-distance trails and historic sites. The title of oldest state park in the United States is claimed by Niagara Falls State Park in New York, however several public parks previously or currently maintained at the state level pre-date it. Indian Springs State Park has been operated continuously by the state of Georgia as a park since 1825. In 1864 Yosemite Valley and Mariposa Grove were ceded by the government to California until Yosemite National Park was proclaimed in 1890. In 1878 Wisconsin set aside a vast swath of its forests as The State Park but, needing money. The first state park with the designation of state park was Mackinac Island State Park in 1895, list of U. S. state parks National Association of State Park Directors Wilderness preservation systems in the United States Ahlgren, Carol.
The Civilian Conservation Corps and Wisconsin State Park Development, the State Park Movement in America, A Critical Review excerpt and text search Larson, Zeb. Silver Falls State Park and the Early Environmental Movement, oregon Historical Quarterly 112#1 pp, 34-57 in JSTOR Newton, Norman T. When Forests Trumped Parks, The Maryland Experience, 1906-1950, Maryland Historical Magazine 101#2 pp, 203-224
Yosemite National Park
Yosemite National Park is a national park spanning portions of Tuolumne and Madera counties in Northern California. The park, which is managed by the National Park Service, on average, about 4 million people visit Yosemite each year, and most spend the majority of their time in the seven square miles of Yosemite Valley. The park set a record in 2016, surpassing 5 million visitors for the first time in its history. Almost 95% of the park is designated wilderness, Yosemite was central to the development of the national park idea. First, Galen Clark and others lobbied to protect Yosemite Valley from development, Yosemite is one of the largest and least fragmented habitat blocks in the Sierra Nevada, and the park supports a diversity of plants and animals. The park has a range from 2,127 to 13,114 feet and contains five major vegetation zones, chaparral/oak woodland, lower montane forest, upper montane forest, subalpine zone. Of Californias 7,000 plant species, about 50% occur in the Sierra Nevada, there is suitable habitat for more than 160 rare plants in the park, with rare local geologic formations and unique soils characterizing the restricted ranges many of these plants occupy.
The geology of the Yosemite area is characterized by granitic rocks, about 10 million years ago, the Sierra Nevada was uplifted and tilted to form its relatively gentle western slopes and the more dramatic eastern slopes. The uplift increased the steepness of stream and river beds, resulting in formation of deep, about one million years ago and ice accumulated, forming glaciers at the higher alpine meadows that moved down the river valleys. Ice thickness in Yosemite Valley may have reached 4,000 feet during the early glacial episode, the downslope movement of the ice masses cut and sculpted the U-shaped valley that attracts so many visitors to its scenic vistas today. The name Yosemite originally referred to the name of a tribe which was driven out of the area by the Mariposa Battalion. Before the area was called Ahwahnee by indigenous people, as revealed by archeological finds, the Yosemite Valley has been inhabited for nearly 3,000 years, though humans may have first visited the area as long as 8,000 to 10,000 years ago.
The indigenous natives called themselves the Ahwahneechee, meaning dwellers in Ahwahnee and they are related to the Northern Paiute and Mono tribes. Many tribes visited the area to trade, including nearby Central Sierra Miwoks, a major trading route went over Mono Pass and through Bloody Canyon to Mono Lake, just to the east of the Yosemite area. Vegetation and game in the region were similar to that present today, acorns were a staple to their diet, as well as seeds and plants, salmon. In 1851 as part of the Mariposa Wars intended to suppress Native American resistance and he was pursuing forces of around 200 Ahwahneechee led by Chief Tenaya. Accounts from this battalion were the first well-documented reports of ethnic Europeans entering Yosemite Valley, attached to Savages unit was Dr. Lafayette Bunnell, the company physician, who wrote about his awestruck impressions of the valley in The Discovery of the Yosemite. Bunnell is credited with naming Yosemite Valley, based on his interviews with Chief Tenaya, Bunnell wrote that Chief Tenaya was the founder of the Pai-Ute Colony of Ah-wah-nee
Lava Beds National Monument
Lava Beds National Monument is located in northeastern California, in Siskiyou and Modoc counties. The Monument lies on the flank of the Medicine Lake Volcano. The region in and around Lava Beds Monument lies at the junction of the Sierra-Klamath, the Monument was established as a United States National Monument on November 21,1925, and includes more than 46,000 acres. Lava Beds National Monument has numerous lava tube caves, with twenty-five having marked entrances and developed trails for public access, the monument offers trails through the high Great Basin xeric shrubland desert landscape and the volcanic field. 1872–1873, this area was the site of the Modoc War, the area of Captain Jacks Stronghold was named in his honor. Volcanic eruptions on the Medicine Lake shield volcano have created a rugged landscape punctuated by these many landforms of volcanism. Cinder cones are formed when magma is under great pressure and it is released in a fountain of lava, blown into the air from a central vent.
The lava cools as it falls, forming cinders that pile up around the vent, when the pressure has been relieved, the rest of the lava flows from the base of the cone. Cinder cones typically only erupt once, the cinder cones of Hippo Butte, Three Sisters, Juniper Butte, and Crescent Butte are all older than the Mammoth and Modoc Crater flows, more than 30, 000–40,000 years old. Eagle Nest Butte and Bearpaw Butte are 114,000 years old, Schonchin Butte cinder cone and the andesitic flow from its base were formed around 62,000 years ago. The flow that formed Valentine Cave erupted 10,850 years ago, an eruption that formed The Castles is younger than the Mammoth Crater flows. Even younger were eruptions from Fleener Chimneys, such as the Devils Homestead flow,10,500 years ago, about 1,110 years ago, plus or minus 60 years, the Callahan flow was produced by an eruption from Cinder Butte. Though Cinder Butte is just outside the boundary of the monument, spatter cones are built out of thicker lava. The lava is thrown out of the vent and builds, layer by layer, Fleener Chimneys and Black Crater are examples of spatter cones.
Roughly ninety percent of the lava in the Lava Beds Monument is basaltic, there are primarily two kinds of basaltic lava flows, pahoehoe and aa. Pahoehoe is smooth, often ropy and is the most common type of lava in Lava Beds, aa is formed when pahoehoe cools and loses some of its gases. Aa is rough and jagged, an excellent example is the Devils Homestead lava flow, most of the rest of the lava in the monument is andesitic. Pumice, a type of lava, is found covering the monument
Alpine County, California
Alpine County, officially the County of Alpine, is a county in the U. S. state of California. As of the 2010 census, the population was 1,175, making it Californias least populous county. The county seat is the Census Designated Place of Markleeville, There are no incorporated cities in the county. Alpine County is in the Sierra Nevada, between Lake Tahoe and Yosemite National Park, Alpine County was created on March 16,1864, during a silver boom in the wake of the nearby Comstock Lode discovery. It was named because of its resemblance to the Swiss Alps, the County was formed from parts of Amador, Calaveras, El Dorado and Tuolumne Counties. At its formation, the County had a population of about 11,000 with its County Seat at Silver Mountain City, by 1868, the local silver mines had proven unfruitful, and the population fell to about 1,200. The County Seat was moved to Markleeville in 1875, after the silver rush, Alpine Countys economy consisted almost entirely of farming and logging. By the 1920s, the population had fallen to just 200 people, with the construction of the Bear Valley and Kirkwood ski resorts in the late 1960s, the population increased to the present level.
According to the U. S. Census Bureau, the county has an area of 743 square miles, the federal government owns about 96% of Alpine County, the highest percentage in California. Eldorado National Forest Stanislaus National Forest Toiyabe National Forest The 2010 United States Census reported that Alpine County had a population of 1,175. The racial makeup of Alpine County was 881 White,0 African American,240 Native American,7 Asian,0 Pacific Islander,19 from other races, Hispanic or Latino of any race were 84 persons. As of the census of 2000, there were 1,208 people,483 households, the population density was 2 people per square mile. There were 1,514 housing units at a density of 2 per square mile. The racial makeup of the county was 73. 7% White,0. 6% Black or African American,18. 9% Native American,0. 3% Asian,0. 1% Pacific Islander,1. 4% from other races, and 5. 1% from two or more races. 7. 8% of the population were Hispanic or Latino of any race,12. 1% were of German,12. 1% Irish,9. 3% English,6. 5% American and 5.
7% Italian ancestry according to Census 2000. 95. 0% spoke English,3. 1% Spanish and 2. 0% Washo as their first language,27. 7% of all households were made up of individuals and 5. 4% had someone living alone who was 65 years of age or older. The average household size was 2.50 and the family size was 2.96. In the county, the population was out with 22. 8% under the age of 18,10. 4% from 18 to 24,27. 5% from 25 to 44,29. 3% from 45 to 64
Lassen Volcanic National Park
Lassen Volcanic National Park is a United States National Park in northeastern California. The dominant feature of the park is Lassen Peak, the largest plug dome volcano in the world, Lassen Volcanic National Park started as two separate national monuments designated by President Theodore Roosevelt in 1907, Cinder Cone National Monument and Lassen Peak National Monument. The source of heat for volcanism in the Lassen area is subduction off the Northern California coast of the Gorda Plate diving below the North American Plate, the area surrounding Lassen Peak is still active with boiling mud pots, stinking fumaroles, and churning hot springs. Lassen Volcanic National Park is one of the few areas in the world where all four types of volcano can be found, the park is accessible via State Routes SR89 and SR44. SR89 passes north-south through the park, beginning at SR36 to the south, SR89 passes immediately adjacent the base of Lassen Peak. A large lodge with concession facilities was located near the south-west entrance, a new, full-service visitor center was constructed in the same location, and opened to the public in 2008.
Near the old location was located Lassen Ski Area. Native Americans have inhabited the area long before white settlers first saw Lassen. The natives knew that the peak was full of fire and water, White immigrants in the mid-19th century used Lassen Peak as a landmark on their trek to the fertile Sacramento Valley. One of the guides to these immigrants was a Danish blacksmith named Peter Lassen, Lassen Peak was named after him. Nobles Emigrant Trail was cut through the area and passed Cinder Cone. Inconsistent newspaper accounts reported by witnesses from 1850 to 1851 described seeing fire thrown to a terrible height, as late as 1859, a witness reported seeing fire in the sky from a distance, attributing it to an eruption. Early geologists and volcanologists who studied the Cinder Cone concluded the last eruption occurred between 1675 and 1700, after the 1980 eruption of Mount St. Helens, the United States Geological Survey began reassessing the potential risk of other active volcanic areas in the Cascade Range.
Further study of Cinder Cone estimated the last eruption occurred between 1630 and 1670, recent tree-ring analysis has placed the date at 1666. The Lassen area was first protected by being designated as the Lassen Peak Forest Preserve, Lassen Peak and Cinder Cone were declared as U. S. National Monuments in May 1907 by President Theodore Roosevelt. Starting in May 1914 and lasting until 1921, a series of minor to major eruptions occurred on Lassen and these events created a new crater, and released lava and a great deal of ash. Fortunately, because of warnings, no one was killed, because of the eruptive activity, which continued through 1917, and the areas stark volcanic beauty, Lassen Peak, Cinder Cone and the area surrounding were declared a National Park on August 9,1916. The 29-mile Main Park Road was constructed between 1925 and 1931, just 10 years after Lassen Peak erupted, near Lassen Peak the road reaches 8,512 feet, making it the highest road in the Cascade Mountains
Kings Canyon National Park
Kings Canyon National Park is a national park in the southern Sierra Nevada, east of Fresno, California. The park was established in 1940 and covers 461,901 acres and it incorporated General Grant National Park, established in 1890 to protect the General Grant Grove of giant sequoias. The park is north of and contiguous with Sequoia National Park and they were designated the UNESCO Sequoia-Kings Canyon Biosphere Reserve in 1976. Humans have inhabited the area for thousands of years, the first Native Americans in the area were Paiute peoples, who moved into the region from their ancestral home east of Mono Lake. The Paiute Nation people used deer and other animals for food. They created trade routes that extended down the slope of the Sierra into the Owens Valley. Kings Canyon had been known to white settlers since the mid-19th century, United States Secretary of the Interior Harold Ickes fought to create the Kings Canyon National Park. He hired Ansel Adams to photograph and document this among other parks, the bill combined the General Grant Grove with the backcountry beyond Zumwalt Meadow.
Kings Canyons future was in doubt for nearly fifty years, some wanted to build a dam at the western end of the valley, while others wanted to preserve it as a park. The debate was settled in 1965, when the valley, along with Tehipite Valley, was added to the park, Kings Canyon National Park consists of two sections. The parks Giant Sequoia forests are part of 202,430 acres of old-growth forests shared by Sequoia and this section of the park is mostly mixed conifer forest, and is readily accessible via paved highways. Both the South and Middle Forks of the Kings Rivers have extensive glacial canyons, one portion of the South Fork canyon, known as the Kings Canyon, gives the entire park its name. Kings Canyon, with a depth of 8,200 feet, is one of the deepest canyons in the United States. The canyon was carved by glaciers out of granite, the Kings Canyon, and its developed area, Cedar Grove, is the only portion of the main part of the park that is accessible by motor vehicle. Both the Kings Canyon and its Middle Fork twin, Tehipite Valley, are deeply incised, U-shaped glacial gorges with relatively flat floors and towering granite cliffs thousands of feet high.
In addition, the canyon has several systems, one of which is Boyden Cave. To the east of the canyons are the peaks of the Sierra Crest, which attain an elevation of 14,248 feet NAVD88 at the summit of North Palisade. This is classic high Sierra country, barren ridges and glacially scoured lake-filled basins
Lead is a chemical element with atomic number 82 and symbol Pb. When freshly cut, it is bluish-white, it tarnishes to a dull gray upon exposure to air and it is a soft and heavy metal with a density exceeding that of most common materials. Lead has the second-highest atomic number of the stable elements. Lead is a relatively unreactive post-transition metal and its weak metallic character is illustrated by its amphoteric nature and tendency to form covalent bonds. Compounds of lead are found in the +2 oxidation state. Exceptions are mostly limited to organolead compounds, like the lighter members of the group, lead exhibits a tendency to bond to itself, it can form chains and polyhedral structures. Lead is easily extracted from its ores and was known to people in Western Asia. A principal ore of lead, often bears silver, Lead production declined after the fall of Rome and did not reach comparable levels again until the Industrial Revolution. Nowadays, global production of lead is about ten million tonnes annually, Lead has several properties that make it useful, high density, low melting point and relative inertness to oxidation.
In the late 19th century, lead was recognized as poisonous, Lead is a neurotoxin that accumulates in soft tissues and bones, damaging the nervous system and causing brain disorders and, in mammals, blood disorders. A lead atom has 82 electrons, arranged in a configuration of 4f145d106s26p2. The combined first and second ionization energies—the total energy required to remove the two 6p electrons—is close to that of tin, leads upper neighbor in group 14. This is unusual since ionization energies generally fall going down a group as an elements outer electrons become more distant from the nucleus, the similarity is caused by the lanthanide contraction—the decrease in element radii from lanthanum to lutetium, and the relatively small radii of the elements after hafnium. The contraction is due to shielding of the nucleus by the lanthanide 4f electrons. The combined first four ionization energies of lead exceed those of tin, for this reason lead, unlike tin, mostly forms compounds in which it has an oxidation state of +2, rather than +4.
Relativistic effects, which become particularly prominent at the bottom of the periodic table, as a result, the 6s electrons of lead become reluctant to participate in bonding, a phenomenon called the inert pair effect. A related outcome is that the distance between nearest atoms in crystalline lead is unusually long, the lighter group 14 elements form stable or metastable allotropes having the tetrahedrally coordinated and covalently bonded diamond cubic structure. The energy levels of their outer s- and p-orbitals are close enough to allow mixing into four hybrid sp3 orbitals
Rubidium is a chemical element with symbol Rb and atomic number 37. Rubidium is a soft, silvery-white metallic element of the metal group. Elemental rubidium is highly reactive, with similar to those of other alkali metals. German chemists Robert Bunsen and Gustav Kirchhoff discovered rubidium in 1861 by the developed technique. Rubidiums compounds have various chemical and electronic applications, rubidium metal is easily vaporized and has a convenient spectral absorption range, making it a frequent target for laser manipulation of atoms. Rubidium is not a nutrient for any living organisms. However, rubidium ions have the charge as potassium ions. Rubidium is a soft, silvery-white metal. It is the second most electropositive of the alkali metals. Similar to other metals, rubidium metal reacts violently with water. As with potassium and caesium, this reaction is vigorous enough to ignite the hydrogen gas it produces. Rubidium has reported to ignite spontaneously in air. It forms amalgams with mercury and alloys with gold, caesium and potassium, rubidium has a very low ionization energy of only 406 kJ/mol.
Rubidium and potassium show a very similar purple color in the flame test, rubidium silver iodide has the highest room temperature conductivity of any known ionic crystal, a property exploited in thin film batteries and other applications. Rubidium forms a number of oxides when exposed to air, including rubidium monoxide, Rb6O, rubidium forms salts with halides, producing rubidium fluoride, rubidium chloride, rubidium bromide, and rubidium iodide. Although rubidium is monoisotopic, rubidium in the Earths crust is composed of two isotopes, the stable 85Rb and the radioactive 87Rb, natural rubidium is radioactive, with specific activity of about 670 Bq/g, enough to significantly expose a photographic film in 110 days. Twenty four additional rubidium isotopes have been synthesized with half-lives of less than 3 months, Rubidium-87 has a half-life of 48. 8×109 years, which is more than three times the age of the universe of ×109 years, making it a primordial nuclide. It readily substitutes for potassium in minerals, and is fairly widespread
Sierra Nevada (U.S.)
The Sierra Nevada is a mountain range in the Western United States, between the Central Valley of California and the Basin and Range Province. The vast majority of the lies in the state of California. The Sierra runs 400 miles north-to-south, and is approximately 70 miles across east-to-west, the Sierra is home to three national parks, twenty wilderness areas, and two national monuments. These areas include Yosemite and Kings Canyon National Parks, the character of the range is shaped by its geology and ecology. More than one hundred years ago during the Nevadan orogeny. The range started to uplift four M. A. ago, the uplift caused a wide range of elevations and climates in the Sierra Nevada, which are reflected by the presence of five life zones. Uplift continues due to faulting caused by forces, creating spectacular fault block escarpments along the eastern edge of the southern Sierra. The Sierra Nevada has a significant history, the California Gold Rush occurred in the western foothills from 1848 through 1855.
Due to inaccessibility, the range was not fully explored until 1912, the Sierra Nevada lies in Central and Eastern California, with a very small but historically important spur extending into Nevada. West-to-east, the Sierra Nevadas elevation increases gradually from 1,000 feet in the Central Valley to an height of about 10,500 feet at its crest only 50–75 miles to the east. The east slope forms the steep Sierra Escarpment, unlike its surroundings, the range receives a substantial amount of snowfall and precipitation due to orographic lift. The Sierra Nevada stretches from the Susan River and Fredonyer Pass in the north to Tehachapi Pass in the south and it is bounded on the west by Californias Central Valley and on the east by the Basin and Range Province. The geographical boundary between the Sierra and the Cascades is virtually indistinguishable, with the Fredonyer Pass designation being traditional, physiographically, the Sierra is a section of the Cascade-Sierra Mountains province, which in turn is part of the larger Pacific Mountain System physiographic division.
The range is drained on its western slope by the Central Valley watershed, the northern third of the western Sierra is part of the Sacramento River watershed, and the middle third is drained by the San Joaquin River. The eastern slope watershed of the Sierra is much narrower, its rivers flow out into the endorheic Great Basin of eastern California and western Nevada. Although none of the eastern rivers reach the sea, many of the streams from Mono Lake southwards are diverted into the Los Angeles Aqueduct which provides water to Southern California, the height of the mountains in the Sierra Nevada increases gradually from north to south. Between Fredonyer Pass and Lake Tahoe, the range from 5,000 feet to more than 9,000 feet. The crest near Lake Tahoe is roughly 9,000 feet high, farther south, the highest peak in Yosemite National Park is Mount Lyell
Boron is a chemical element with symbol B and atomic number 5. Produced entirely by cosmic ray spallation and supernovae and not by stellar nucleosynthesis, it is an element in the Solar system. Boron is concentrated on Earth by the water-solubility of its more common naturally occurring compounds and these are mined industrially as evaporites, such as borax and kernite. The largest known deposits are in Turkey, the largest producer of boron minerals. Elemental boron is a metalloid that is found in small amounts in meteoroids, very pure boron is produced with difficulty because of refractory contamination by carbon or other elements. Several allotropes of boron exist, amorphous boron is a powder, crystalline boron is silvery to black, extremely hard. The primary use of boron is as boron filaments with applications similar to carbon fibers in some high-strength materials. Boron is primarily used in chemical compounds, about half of all consumption globally, boron is used as an additive in glass fibers of boron-containing fiberglass for insulation and structural materials.
The next leading use is in polymers and ceramics in high-strength, lightweight structural, borosilicate glass is desired for its greater strength and thermal shock resistance than ordinary soda lime glass. Boron compounds are used as fertilizers in agriculture and in sodium perborate bleaches, a small amount of boron is used as a dopant in semiconductors, and reagent intermediates in the synthesis of organic fine chemicals. A few boron-containing organic pharmaceuticals are used or are in study, natural boron is composed of two stable isotopes, one of which has a number of uses as a neutron-capturing agent. In biology, borates have low toxicity in mammals, but are toxic to arthropods and are used as insecticides. Boric acid is mildly antimicrobial, and several natural boron-containing organic antibiotics are known, small amounts of boron compounds play a strengthening role in the cell walls of all plants, making boron a necessary plant nutrient. Boron is involved in the metabolism of calcium in both plants and animals and it is considered an essential nutrient for humans, and boron deficiency is implicated in osteoporosis.
The word boron was coined from borax, the mineral from which it was isolated, by analogy with carbon, marco Polo brought some glazes back to Italy in the 13th century. Agricola, around 1600, reports the use of borax as a flux in metallurgy, in 1777, boric acid was recognized in the hot springs near Florence and became known as sal sedativum, with primarily medical uses. The rare mineral is called sassolite, which is found at Sasso, Sasso was the main source of European borax from 1827 to 1872, when American sources replaced it. Boron compounds were relatively rarely used until the late 1800s when Francis Marion Smiths Pacific Coast Borax Company first popularized and produced them in volume at low cost