An ice age is a long period of reduction in the temperature of the Earth's surface and atmosphere, resulting in the presence or expansion of continental and polar ice sheets and alpine glaciers. Earth is in the Quaternary glaciation, known in popular terminology as the Ice Age. Individual pulses of cold climate are termed "glacial periods", intermittent warm periods are called "interglacials", with both climatic pulses part of the Quaternary or other periods in Earth's history. In the terminology of glaciology, ice age implies the presence of extensive ice sheets in both northern and southern hemispheres. By this definition, we are in an interglacial period—the Holocene; the amount of heat trapping gases emitted into Earth's Oceans and atmosphere will prevent the next ice age, which otherwise would begin in around 50,000 years, more glacial cycles. In 1742, Pierre Martel, an engineer and geographer living in Geneva, visited the valley of Chamonix in the Alps of Savoy. Two years he published an account of his journey.
He reported that the inhabitants of that valley attributed the dispersal of erratic boulders to the glaciers, saying that they had once extended much farther. Similar explanations were reported from other regions of the Alps. In 1815 the carpenter and chamois hunter Jean-Pierre Perraudin explained erratic boulders in the Val de Bagnes in the Swiss canton of Valais as being due to glaciers extending further. An unknown woodcutter from Meiringen in the Bernese Oberland advocated a similar idea in a discussion with the Swiss-German geologist Jean de Charpentier in 1834. Comparable explanations are known from the Val de Ferret in the Valais and the Seeland in western Switzerland and in Goethe's scientific work; such explanations could be found in other parts of the world. When the Bavarian naturalist Ernst von Bibra visited the Chilean Andes in 1849–1850, the natives attributed fossil moraines to the former action of glaciers. Meanwhile, European scholars had begun to wonder. From the middle of the 18th century, some discussed ice as a means of transport.
The Swedish mining expert Daniel Tilas was, in 1742, the first person to suggest drifting sea ice in order to explain the presence of erratic boulders in the Scandinavian and Baltic regions. In 1795, the Scottish philosopher and gentleman naturalist, James Hutton, explained erratic boulders in the Alps by the action of glaciers. Two decades in 1818, the Swedish botanist Göran Wahlenberg published his theory of a glaciation of the Scandinavian peninsula, he regarded glaciation as a regional phenomenon. Only a few years the Danish-Norwegian geologist Jens Esmark argued a sequence of worldwide ice ages. In a paper published in 1824, Esmark proposed changes in climate as the cause of those glaciations, he attempted to show. During the following years, Esmark's ideas were discussed and taken over in parts by Swedish and German scientists. At the University of Edinburgh Robert Jameson seemed to be open to Esmark's ideas, as reviewed by Norwegian professor of glaciology Bjørn G. Andersen. Jameson's remarks about ancient glaciers in Scotland were most prompted by Esmark.
In Germany, Albrecht Reinhard Bernhardi, a geologist and professor of forestry at an academy in Dreissigacker, since incorporated in the southern Thuringian city of Meiningen, adopted Esmark's theory. In a paper published in 1832, Bernhardi speculated about former polar ice caps reaching as far as the temperate zones of the globe. In 1829, independently of these debates, the Swiss civil engineer Ignaz Venetz explained the dispersal of erratic boulders in the Alps, the nearby Jura Mountains, the North German Plain as being due to huge glaciers; when he read his paper before the Schweizerische Naturforschende Gesellschaft, most scientists remained sceptical. Venetz convinced his friend Jean de Charpentier. De Charpentier transformed Venetz's idea into a theory with a glaciation limited to the Alps, his thoughts resembled Wahlenberg's theory. In fact, both men shared the same volcanistic, or in de Charpentier's case rather plutonistic assumptions, about the Earth's history. In 1834, de Charpentier presented his paper before the Schweizerische Naturforschende Gesellschaft.
In the meantime, the German botanist Karl Friedrich Schimper was studying mosses which were growing on erratic boulders in the alpine upland of Bavaria. He began to wonder. During the summer of 1835 he made some excursions to the Bavarian Alps. Schimper came to the conclusion that ice must have been the means of transport for the boulders in the alpine upland. In the winter of 1835 to 1836 he held. Schimper assumed that there must have been global times of obliteration with a cold climate and frozen water. Schimper spent the summer months of 1836 at Devens, near Bex, in the Swiss Alps with his former university friend Louis Agassiz and Jean de Charpentier. Schimper, de Charpentier and Venetz convinced Agassiz that there had been a time of glaciation. During the winter of 1836/37, Agassiz and Schimper developed the theory of a sequence of glaciations, they drew upon the preceding works of Venetz, de Charpentier and on their own fieldwork. Agassiz appears to have been familiar with Bernhardi's paper at that time.
At the beginning of 1837, Schimper coined the term "ice age" for the period of the glaciers. In July 1837 Ag
Owens Valley is the now-arid valley of the Owens River in eastern California in the United States, to the east of the Sierra Nevada and west of the White Mountains and Inyo Mountains on the west edge of the Great Basin. The mountain peaks on either side reach above 14,000 feet in elevation, while the floor of the Owens Valley is about 4,000 feet, making the valley one of the deepest in the United States; the Sierra Nevada casts the valley in a rain shadow, which makes Owens Valley "the Land of Little Rain." The bed of Owens Lake, now a predominantly dry endorheic alkali flat, sits on the southern end of the valley. The valley provides water to the Los Angeles Aqueduct, the source of one-third of the water for Los Angeles, is infamous as the scene of one of the fiercest and longest-running episodes of the California Water Wars; these episodes inspired aspects of the 1974 film Chinatown. As well, the now-arid nature of the valley is due to LADWP depleting the water of the region. For example, Owens Lake was emptied by 1926, only 13 years after LA began diverting water.
Towns in the Owens Valley include Bishop, Lone Pine and Big Pine. The major road in the Owens Valley is U. S. Route 395. About three million years ago, the Sierra Nevada Fault and the White Mountains Fault systems became active with repeated episodes of slip earthquakes producing the impressive relief of the eastern Sierra Nevada and White Mountain escarpments that bound the northern Owens Valley-Mono Basin region. Owens Valley is a graben—a downdropped block of land between two vertical faults—the westernmost in the Basin and Range Province, it is part of a trough which extends from Oregon to Death Valley called the Walker Lane. The western flank of much of the valley has large moraines coming off the Sierra Nevada; these unsorted piles of rock and dust were pushed to where they are by glaciers during the last ice age. An excellent example of a moraine is on State Route 168; this graben was formed by a long series of earthquakes, such as the 1872 Lone Pine earthquake, that have moved the graben down and helped move the Sierra Nevada up.
The graben is much larger. The topmost part of this escarpment is exposed at Alabama Hills; the Owens Valley has many mini-volcanoes, such as Crater Mountain in the Big Pine volcanic field. Smaller versions of the Devils Postpile, can be found, by Little Lake; the valley contains plants adapted to alkali flat habitat. One of these, the Owens Valley checkerbloom, is endemic to Owens Valley; the valley was inhabited in late prehistoric times by the Timbisha in the extreme south end around Owens Lake and by the Mono tribe in the central and northern portions of the valley. The Timbisha speak the Timbisha language, classified in the Numic branch of Uto-Aztecan language family; the closest related languages are Comanche. The Eastern Mono speak a dialect of the Mono language, Numic but is more related to Northern Paiute; the Timbisha presently live in Death Valley at Furnace Creek although most families have summer homes in the Lone Pine colony. The Eastern Mono live in several colonies from Lone Pine to Bishop.
Trade between Native Americans of the Owens Valley and coastal tribes such as the Chumash has been indicated by the archaeological record. On May 1, 1834, Joseph R. Walker entered Owens Valley at the mouth of Walker Pass. Walker and his group of 52 men traveled up the valley on their way back to the Humboldt Sink, back up the Humboldt River to the Rocky Mountains. In 1845, John C. Fremont named the Owens valley and lake for Richard Owens, one of his guides. Camp Independence was established on Oak Creek nearby modern Independence, California, on July 4, 1862, during the Owens Valley Indian War. From 1942 to 1945, during World War II, the first Japanese American Internment camp operated in the valley at Manzanar near Independence, California. In the early 20th century, the valley became the scene of a struggle between local residents and the city of Los Angeles over water rights. William Mulholland, superintendent of the Los Angeles Department of Water and Power, planned the 223-mile Los Angeles Aqueduct, completed in 1913, which diverted water from the Owens River.
The water rights were acquired in a deceitful manner splitting water cooperatives and pitting neighbors against one another. In 1924, local farmers were fed up with the purchases and erupted in violence, sabotaging parts of the water system. Los Angeles acquired a large portion of the water rights to over 300,000 acres of land in the valley completely diverting the inflows of water away from Owens Lake. Gary Libecap of the University of California, Santa Barbara observed that the price that Los Angeles was willing to pay to other water sources per acre-foot of water was far higher than what the farmers received. Farmers who resisted the pressure from Los Angeles until 1930 received the highest price for their land. However, the sale of their land brought the farmers more income than if they had kept the land for farming and ranching. None of the sales were made under threat of eminent domain; as a result of these acquisitions, the lake subsequently dried up complet
Thenardite is an anhydrous sodium sulfate mineral, Na2SO4 which occurs in arid evaporite environments. It occurs in dry caves and old mine workings as an efflorescence and as a crusty sublimate deposit around fumaroles, it occurs in volcanic caves on Italy. It was first described in 1825 for an occurrence in the Espartinas Saltworks, Madrid and was named for the French chemist, Louis Jacques Thénard. Thenardite crystallizes in the orthorhombic system and forms yellowish, reddish to gray white prismatic crystals although in massive crust deposits. Thenardite is white in shortwave and yellow-green in longwave UV radiation. In humid conditions, thenardite absorbs water and converts to the mineral mirabilite, Na2SO4·10H2O
Halite known as rock salt, is a type of salt, the mineral form of sodium chloride. Halite forms isometric crystals; the mineral is colorless or white, but may be light blue, dark blue, pink, orange, yellow or gray depending on inclusion of other materials and structural or isotopic abnormalities in the crystals. It occurs with other evaporite deposit minerals such as several of the sulfates and borates; the name halite is derived from the Ancient Greek word for salt, ἅλς. Halite occurs in vast beds of sedimentary evaporite minerals that result from the drying up of enclosed lakes and seas. Salt beds may underlie broad areas. In the United States and Canada extensive underground beds extend from the Appalachian basin of western New York through parts of Ontario and under much of the Michigan Basin. Other deposits are in Ohio, New Mexico, Nova Scotia and Saskatchewan; the Khewra salt mine is a massive deposit of halite near Pakistan. Salt domes are vertical diapirs or pipe-like masses of salt that have been "squeezed up" from underlying salt beds by mobilization due to the weight of overlying rock.
Salt domes contain anhydrite and native sulfur, in addition to halite and sylvite. They are common along the Gulf coasts of Texas and Louisiana and are associated with petroleum deposits. Germany, the Netherlands and Iran have salt domes. Salt glaciers exist in arid Iran where the salt has broken through the surface at high elevation and flows downhill. In all of these cases, halite is said to be behaving in the manner of a rheid. Unusual, fibrous vein filling halite is found in France and a few other localities. Halite crystals termed hopper crystals appear to be "skeletons" of the typical cubes, with the edges present and stairstep depressions on, or rather in, each crystal face. In a crystallizing environment, the edges of the cubes grow faster than the centers. Halite crystals form quickly in some evaporating lakes resulting in modern artifacts with a coating or encrustation of halite crystals. Halite flowers are rare stalactites of curling fibers of halite that are found in certain arid caves of Australia's Nullarbor Plain.
Halite stalactites and encrustations are reported in the Quincy native copper mine of Hancock, Michigan. The worlds largest underground salt mine is the Sifto Salt Mine, it uses the Room and Pillar Mining Method. It is located half a kilometre under Lake Huron in Canada. In the United Kingdom there are three mines. Salt is used extensively in cooking as a flavor enhancer, to cure a wide variety of foods such as bacon and fish, it is used in food preservation methods across various cultures. Larger pieces dusted over food from a shaker as finishing salt. Halite is often used both residentially and municipally for managing ice; because brine has a lower freezing point than pure water, putting salt or saltwater on ice, below 0 °C will cause it to melt. It is common for homeowners in cold climates to spread salt on their sidewalks and driveways after a snow storm to melt the ice, it is not necessary to use so much salt that the ice is melted. Many cities will spread a mixture of sand and salt on roads during and after a snowstorm to improve traction.
Using Salt Brine is more effective than spreading dry salt because moisture is necessary for the freezing-point depression to work and wet salt sticks to the roads better. Otherwise the salt can be wiped away by traffic. In addition to de-icing, rock salt is used in agriculture. An example of this would be inducing salt stress to suppress the growth of annual meadow grass in turf production. Other examples involve exposing weeds to salt water to dehydrate and kill them preventing them from affecting other plants. Salt is used as a household cleaning product, its coarse nature allows for its use in various cleaning scenarios including grease/oil removal, stain removal, dries out and hardens sticky spills for an easier clean. Some cultures in Africa and Brazil, prefer a wide variety of different rock salts for different dishes. Pure salt is avoided. Many recipes call for particular kinds of rock salt, imported pure salt has impurities added to adapt to local tastes. Salt was used as a form of currency in barter systems and was exlcusively controlled by authorities and their appointees.
In some ancient civilizations the practice of Salting The Earth was done to make conquered land of an enemy infertile and inhospitable as an act of domination. This act is known as Salting The Earth. We see biblical reference to this practice in Judges 9:45: “he killed the people in it, pulled the wall down and sowed the site with salt.”. Salt Coarse salt Salt tectonics
In chemistry, a hydrate is a substance that contains water or its constituent elements. The chemical state of the water varies between different classes of hydrates, some of which were so labeled before their chemical structure was understood. In organic chemistry, a hydrate is a compound formed by the addition of water or its elements to another molecule. For example: ethanol, CH3–CH2–OH, is the product of the hydration reaction of ethene, CH2=CH2, formed by the addition of H to one C and OH to the other C, so can be considered as the hydrate of ethene. A molecule of water may be eliminated, for example by the action of sulfuric acid. Another example is chloral hydrate, CCl3–CH2, which can be formed by reaction of water with chloral, CCl3–CH=O. Many organic molecules, as well as inorganic molecules, form crystals that incorporate water into the crystalline structure without chemical alteration of the organic molecule; the sugar trehalose, for example, exists as a dihydrate. Protein crystals have as much as 50% water content.
Molecules are labeled as hydrates for historical reasons not covered above. Glucose, C6H12O6, was thought of as C66 and described as a carbohydrate. Methanol is sold as "methyl hydrate", implying the incorrect formula CH3OH2, while the correct formula is CH3–OH. Hydrates are inorganic salts "containing water molecules combined in a definite ratio as an integral part of the crystal" that are either bound to a metal center or that have crystallized with the metal complex; such hydrates are said to contain water of crystallization or water of hydration. If the water is heavy water, where the hydrogen involved is the isotope deuterium the term deuterate may be used in place of hydrate. A colorful example is cobalt chloride, which turns from blue to red upon hydration, can therefore be used as a water indicator; the notation "hydrated compound⋅nH2O", where n is the number of water molecules per formula unit of the salt, is used to show that a salt is hydrated. The n is a low integer, though it is possible for fractional values to occur.
For example, in a monohydrate n is one, in a hexahydrate n is 6. Numerical prefixes of Greek origin are: A hydrate which has lost water is referred to as an anhydride. A substance that does not contain any water is referred to as anhydrous; some anhydrous compounds are hydrated so that they are said to be hygroscopic and are used as drying agents or desiccants. Clathrate hydrates are water ice with gas molecules trapped within. An important example is methane hydrate. Nonpolar molecules such as methane can form clathrate hydrates with water under high pressure. Although there is no hydrogen bonding between water and guest molecules when methane is the guest molecule of the clathrate, guest-host hydrogen bonding forms when the guest is a larger organic molecule such as tetrahydrofuran. In such cases the guest-host hydrogen bonds result in the formation of L-type Bjerrum defects in the clathrate lattice; the stability of hydrates is determined by the nature of the compounds, their temperature, the relative humidity
A mineral is, broadly speaking, a solid chemical compound that occurs in pure form. A rock may consist of a single mineral, or may be an aggregate of two or more different minerals, spacially segregated into distinct phases. Compounds that occur only in living beings are excluded, but some minerals are biogenic and/or are organic compounds in the sense of chemistry. Moreover, living beings synthesize inorganic minerals that occur in rocks. In geology and mineralogy, the term "mineral" is reserved for mineral species: crystalline compounds with a well-defined chemical composition and a specific crystal structure. Minerals without a definite crystalline structure, such as opal or obsidian, are more properly called mineraloids. If a chemical compound may occur with different crystal structures, each structure is considered different mineral species. Thus, for example and stishovite are two different minerals consisting of the same compound, silicon dioxide; the International Mineralogical Association is the world's premier standard body for the definition and nomenclature of mineral species.
As of November 2018, the IMA recognizes 5,413 official mineral species. Out of more than 5,500 proposed or traditional ones; the chemical composition of a named mineral species may vary somewhat by the inclusion of small amounts of impurities. Specific varieties of a species sometimes have official names of their own. For example, amethyst is a purple variety of the mineral species quartz; some mineral species can have variable proportions of two or more chemical elements that occupy equivalent positions in the mineral's structure. Sometimes a mineral with variable composition is split into separate species, more or less arbitrarily, forming a mineral group. Besides the essential chemical composition and crystal structure, the description of a mineral species includes its common physical properties such as habit, lustre, colour, tenacity, fracture, specific gravity, fluorescence, radioactivity, as well as its taste or smell and its reaction to acid. Minerals are classified by key chemical constituents.
Silicate minerals comprise 90% of the Earth's crust. Other important mineral groups include the native elements, oxides, carbonates and phosphates. One definition of a mineral encompasses the following criteria: Formed by a natural process. Stable or metastable at room temperature. In the simplest sense, this means. Classical examples of exceptions to this rule include native mercury, which crystallizes at −39 °C, water ice, solid only below 0 °C. Modern advances have included extensive study of liquid crystals, which extensively involve mineralogy. Represented by a chemical formula. Minerals are chemical compounds, as such they can be described by fixed or a variable formula. Many mineral groups and species are composed of a solid solution. For example, the olivine group is described by the variable formula 2SiO4, a solid solution of two end-member species, magnesium-rich forsterite and iron-rich fayalite, which are described by a fixed chemical formula. Mineral species themselves could have a variable composition, such as the sulfide mackinawite, 9S8, a ferrous sulfide, but has a significant nickel impurity, reflected in its formula.
Ordered atomic arrangement. This means crystalline. An ordered atomic arrangement gives rise to a variety of macroscopic physical properties, such as crystal form and cleavage. There have been several recent proposals to classify amorphous substances as minerals; the formal definition of a mineral approved by the IMA in 1995: "A mineral is an element or chemical compound, crystalline and, formed as a result of geological processes." Abiogenic. Biogenic substances are explicitly excluded by the IMA: "Biogenic substances are chemical compounds produced by biological processes without a geological component and are not regarded as minerals. However, if geological processes were involved in the genesis of the compound the product can be accepted as a mineral."The first three general characteristics are less debated than the last two. Mineral classification schemes and their definitions are evolving to match recent advances in mineral science. Recent changes have included the addition of an organic class, in both the new Dana and the Strunz classification schemes.
The organic class includes a rare group of minerals with hydrocarbons. The IMA Commission on New Minerals and Mineral Names adopted in 2009 a hierarchical scheme for the naming and classification of mineral groups and group names and established seven commissions and four working groups to review and classify minerals into an official listing of their published names. According to these new r
Los Angeles Aqueduct
The Los Angeles Aqueduct system, comprising the Los Angeles Aqueduct and the Second Los Angeles Aqueduct, is a water conveyance system and operated by the Los Angeles Department of Water and Power. The Owens Valley aqueduct was designed and built by the city's water department, at the time named The Bureau of Los Angeles Aqueduct, under the supervision of the department's Chief Engineer William Mulholland; the system delivers water from the Owens River in the Eastern Sierra Nevada Mountains to Los Angeles, California. In 1971 it was recognized by the American Society of Civil Engineers on the List of Historic Civil Engineering Landmarks, its construction was controversial from the start, as water diversions to Los Angeles all but ended agriculture in the Owens Valley. Since its continued operation has led to public debate and court battles over the environmental impacts of the aqueduct on Mono Lake and other ecosystems; the aqueduct project began in 1905 when the voters of Los Angeles approved a US$1.5 million bond for the'purchase of lands and water and the inauguration of work on the aqueduct'.
On June 12, 1907 a second bond was passed with a budget of US$24.5 million to fund construction. Construction was divided into 11 divisions and a cement plant; the number of men who were on the payroll the first year was 2,629 and this number peaked at 6,060 in May 1909. In 1910, employment dropped to 1,150 due to financial reasons but rebounded in the year. Between 1911 and 1912 employment ranged from 2,800 to 3,800 workers; the number of laborers working on the aqueduct at its peak was 3,900. In 1913 the City of Los Angeles completed construction of the first Los Angeles Aqueduct; the aqueduct as constructed consisted of six storage reservoirs and 215 mi of conduit. Beginning three and one half miles north of Black Rock Springs, the aqueduct diverts the Owens River into an unlined canal to begin its 233 mi journey south to the Lower San Fernando Reservoir; this reservoir was renamed the Lower Van Norman Reservoir. The original project consisted of 24 mi of open unlined canal, 37 mi of lined open canal, 97 mi of covered concrete conduit, 43 mi of concrete tunnels, 12.00 mi steel siphons, 120 mi of railroad track, two hydroelectric plants, three cement plants, 170 mi of power lines, 240 mi of telephone line, 500 mi of roads and was expanded with the construction of the Mono Extension and the Second Los Angeles Aqueduct.
The aqueduct uses gravity alone to move the water and uses the water to generate electricity, which makes it cost-efficient to operate. The aqueduct system is still in operation; the construction of the Los Angeles Aqueduct eliminated the Owens Valley as a viable farming community and devastated the Owens Lake ecosystem. A group labeled the "San Fernando Syndicate" – including Fred Eaton, Harrison Otis, Henry Huntington, other wealthy individuals – were a group of investors who bought land in the San Fernando Valley based on inside knowledge that the Los Angeles aqueduct would soon irrigate it and encourage development. Although there is disagreement over the actions of the "syndicate" as to whether they were a "diabolical" cabal or only a group that united the Los Angeles business community behind supporting the aqueduct, Eaton and others connected with the project have long been accused of using deceptive tactics and underhanded methods to obtain water rights and block the Bureau of Reclamation from building water infrastructure for the residents in Owens Valley.
By the 1920s, the aggressive pursuits of the water rights and the diversion of the Owens River precipitated the outbreak of violence known as the California Water Wars. Farmers in Owens Valley attacked infrastructure, dynamiting the aqueduct numerous times and opening sluice gates to divert the flow of water; the aqueduct's water provided developers with the resources to develop the San Fernando Valley and Los Angeles through World War II. Mulholland's role in the vision and completion of the aqueduct and the growth of Los Angeles into a large metropolis is recognized and well-documented; the William Mulholland Memorial Fountain, built in 1940 and located at Riverside Drive and Los Feliz Blvd. in Los Feliz, is dedicated to his memory and contributions. Mulholland Drive and Mulholland Dam are both named for him as well. In an effort to find more water, the city of Los Angeles reached farther north. In 1930, Los Angeles voters passed a third US$38.8 million bond to buy land in the Mono Basin and fund the Mono Basin extension.
The 105 mile extension diverted flows from the Rush Creek, Lee Vining Creek and Parker Creeks that would have flowed into Mono Lake. The construction of the Mono extension consisted of an intake at Lee Vining Creek, the Lee Vining conduit to the Grant Reservoir on Rush Creek, which would have a capacity of 48,000 acre⋅ft, the 12.7 mile Mono Craters Tunnel to the Owens River and a second reservoir named Crowley Lake with a capacity of 183,465 acre⋅ft in Long Valley at the head of the Owens River Gorge. Completed in 1940, diversions began in 1941; the Mono Extension has a design capacity of 400 cu ft/s of flow to the aqueduct however the flow was limited to 123 cu ft/s due to the limited downstream capacity of the Los Angeles Aqueduct. Full appropriation of the water could not be met until the second aqueduct was completed in 1970. Between 1940 and 1970, water exports through the Mono Extension averaged 57