|
Angel Island (California)
Angel Island (Spanish language in California, Spanish: ''Isla de los Ángeles'') is an island in San Francisco Bay. The entire island is included within Angel Island State Park, administered by California State Parks. The island, a California Historical Landmark, has been used by humans for a variety of purposes, including seasonal hunting and gathering by Indigenous peoples, water and timber supply for European ships, ranching by Mexicans, United States military installations, a United States Public Health Service Quarantine Station, and a U.S. Immigration and Naturalization Service, Bureau of Immigration inspection and detention facility. The United States Immigration Station, Angel Island, Angel Island Immigration Station, on the northeast corner of the island, which has been designated a National Historic Landmark, is where officials detained, inspected, and examined approximately one million immigrants, who primarily came from Asia. Geography Angel Island is the second la ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
San Francisco Bay
San Francisco Bay (Chochenyo language, Chochenyo: 'ommu) is a large tidal estuary in the United States, U.S. state of California, and gives its name to the San Francisco Bay Area. It is dominated by the cities of San Francisco, California, San Francisco, San Jose, California, San Jose, and Oakland, California, Oakland. The San Francisco Bay drains water from approximately 40 percent of California. Water from the Sacramento River, Sacramento and San Joaquin River, San Joaquin rivers, and from the Sierra Nevada mountains, flow into Suisun Bay, which then travels through the Carquinez Strait to meet with the Napa River at the entrance to San Pablo Bay, which connects at its south end to San Francisco Bay. It then connects to the Pacific Ocean via the Golden Gate strait. However, this entire group of interconnected bays is often called the ''San Francisco Bay''. The bay was designated a Ramsar Convention, Ramsar Wetland of International Importance on February 2, 2013, and the Port ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
San Jose, California
San Jose, officially the City of San José ( ; ), is a cultural, commercial, and political center within Silicon Valley and the San Francisco Bay Area. With a city population of 997,368 and a metropolitan area population of 1.95 million, it is the most populous city in both the Bay Area and Northern California and the List of United States cities by population, 12th-most populous in the United States. Located in the center of the Santa Clara Valley on the southern shore of San Francisco Bay, San Jose covers an area of and is the county seat, seat of Santa Clara County, California, Santa Clara County. Before the Spanish colonization of the Americas, arrival of the Spanish, the area around San Jose was long inhabited by the Tamyen people, Tamien nation of the Ohlone people San Jose was founded on November 29, 1777, as the ''Pueblo de San José de Our Lady of Guadalupe, Guadalupe'', the first city founded in the Californias. It became a part of Mexico in 1821 after the Mexican Wa ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Subduction Zone Metamorphism
A subduction zone is a region of the Earth's crust where one tectonic plate moves under another tectonic plate; oceanic crust gets recycled back into the mantle and continental crust gets produced by the formation of arc magmas. Arc magmas account for more than 20% of terrestrially produced magmas and are produced by the dehydration of minerals within the subducting slab as it descends into the mantle and are accreted onto the base of the overriding continental plate. Subduction zones host a unique variety of rock types formed by the high-pressure, low-temperature conditions a subducting slab encounters during its descent. The metamorphic conditions the slab passes through in this process generates and alters water bearing (hydrous) mineral phases, releasing water into the mantle. This water lowers the melting point of mantle rock, initiating melting. Understanding the timing and conditions in which these dehydration reactions occur, is key to interpreting mantle melting, volcanic ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Glaucophane
Glaucophane is a mineral and a mineral group belonging to the sodic amphibole supergroup of the double chain inosilicates, with the chemical formula Na2(Mg3Al2)Si8O22(OH)2. Glaucophane crystallizes in the monoclinic system. Name Glaucophane is named for its typical blue color. In Greek, ''glaucophane'' means "blue appearing". As the major mineral component, it is glaucophane's color that gives the "blueschist" metamorphic rock type its name. Characteristics The blue color is very diagnostic for this species. Glaucophane, along with the closely related mineral riebeckite, to which it forms a series with, and their intermediate crossite, are the only well known amphiboles that are commonly blue. Glaucophane forms a solid solution series with ferroglaucophane (). Glaucophane is the magnesium-rich endmember and ferroglaucophane is the iron-rich endmember. Ferroglaucophane is similar to glaucophane but is slightly denser and hence increased specific gravity. The two endmembers a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Jadeite
Jadeite is a pyroxene mineral with composition Na Al Si2 O6. It is hard (Mohs hardness of about 6.5 to 7.0), very tough, and dense, with a specific gravity of about 3.4. It is found in a wide range of colors, but is most often found in shades of green or white. Jadeite is formed only in the subduction zones of continental margins, where rock undergoes metamorphism at high pressure but relatively low temperature. Jadeite is the principal mineral making up the most valuable form of jade, a precious stone particularly prized in China. Most gem-quality jadeite jade comes from northern Myanmar. Jade tools and implements have been found at Stone Age sites, showing that the mineral has been prized by humans since before the beginning of recorded history, written history. Name The name ''jadeite'' is derived (via and ) from the Spanish language, Spanish phrase "piedra de ijada" which means "stone of the side". The Latin version of the name, ''lapis nephriticus'', is the origin of the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mesozoic Era
The Mesozoic Era is the era of Earth's geological history, lasting from about , comprising the Triassic, Jurassic and Cretaceous Periods. It is characterized by the dominance of archosaurian reptiles such as the dinosaurs, and of gymnosperms such as cycads, ginkgoaceae and araucarian conifers; a hot greenhouse climate; and the tectonic break-up of Pangaea. The Mesozoic is the middle of the three eras since complex life evolved: the Paleozoic, the Mesozoic, and the Cenozoic. The era began in the wake of the Permian–Triassic extinction event, the largest mass extinction in Earth's history, and ended with the Cretaceous–Paleogene extinction event, another mass extinction whose victims included the non-avian dinosaurs, pterosaurs, mosasaurs, and plesiosaurs. The Mesozoic was a time of significant tectonic, climatic, and evolutionary activity. The supercontinent Pangaea began to break apart into separate landmasses. The climate of the Mesozoic was varied, alternating bet ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Igneous
Igneous rock ( ), or magmatic rock, is one of the three main rock types, the others being sedimentary and metamorphic. Igneous rocks are formed through the cooling and solidification of magma or lava. The magma can be derived from partial melts of existing rocks in either a planet's mantle or crust. Typically, the melting is caused by one or more of three processes: an increase in temperature, a decrease in pressure, or a change in composition. Solidification into rock occurs either below the surface as intrusive rocks or on the surface as extrusive rocks. Igneous rock may form with crystallization to form granular, crystalline rocks, or without crystallization to form natural glasses. Igneous rocks occur in a wide range of geological settings: shields, platforms, orogens, basins, large igneous provinces, extended crust and oceanic crust. Geological significance Igneous and metamorphic rocks make up 90–95% of the top of the Earth's crust by volume. Igneous rocks ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sedimentary
Sedimentary rocks are types of rock formed by the cementation of sediments—i.e. particles made of minerals (geological detritus) or organic matter (biological detritus)—that have been accumulated or deposited at Earth's surface. Sedimentation is any process that causes these particles to settle in place. Geological detritus originates from weathering and erosion of existing rocks, or from the solidification of molten lava blobs erupted by volcanoes. The geological detritus is transported to the place of deposition by water, wind, ice or mass movement, which are called agents of denudation. Biological detritus is formed by bodies and parts (mainly shells) of dead aquatic organisms, as well as their fecal mass, suspended in water and slowly piling up on the floor of water bodies ( marine snow). Sedimentation may also occur when dissolved minerals precipitate from water solution. The sedimentary rock cover of the continents of the Earth's crust is extensive (73% of the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Franciscan Complex
The Franciscan Complex or Franciscan Assemblage is a geology, geologic term for a late Mesozoic terrane of heterogeneous rock (geology), rocks found throughout the California Coast Ranges, and particularly on the San Francisco Peninsula. It was named by geologist Andrew Lawson, who also named the San Andreas Fault that defines the western extent of the assemblage. The Franciscan Complex is dominated by greywacke sandstones, shales and Conglomerate (geology), conglomerates which have experienced low-grade metamorphism. Other important lithologies include chert, basalt, limestone, serpentinite, and high-pressure, low-temperature metabasites (blueschists and eclogites) and meta-limestones. Fossils like radiolaria are found in chert beds of the Franciscan Complex. These fossils have been used to provide age constraints on the different terranes that constitute the Franciscan. The mining opportunities within the Franciscan are restricted to deposits of cinnabar and limestone. The ou ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Blue Folded Metacherts With Glaucophane-rich (ashy%3F) Layers
Blue is one of the three primary colours in the RYB colour model (traditional colour theory), as well as in the RGB (additive) colour model. It lies between violet and cyan on the spectrum of visible light. The term ''blue'' generally describes colours perceived by humans observing light with a dominant wavelength that's between approximately 450 and 495 nanometres. Most blues contain a slight mixture of other colours; azure contains some green, while ultramarine contains some violet. The clear daytime sky and the deep sea appear blue because of an optical effect known as Rayleigh scattering. An optical effect called the Tyndall effect explains blue eyes. Distant objects appear more blue because of another optical effect called aerial perspective. Blue has been an important colour in art and decoration since ancient times. The semi-precious stone lapis lazuli was used in ancient Egypt for jewellery and ornament and later, in the Renaissance, to make the pigment ultram ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
United States Census Bureau
The United States Census Bureau, officially the Bureau of the Census, is a principal agency of the Federal statistical system, U.S. federal statistical system, responsible for producing data about the American people and American economy, economy. The U.S. Census Bureau is part of the United States Department of Commerce, U.S. Department of Commerce and its Director of the United States Census Bureau, director is appointed by the president of the United States. Currently, Ron S. Jarmin is the acting director of the U.S. Census Bureau. The Census Bureau's primary mission is conducting the United States census, U.S. census every ten years, which allocates the seats of the United States House of Representatives, U.S. House of Representatives to the U.S. state, states based on their population. The bureau's various censuses and surveys help allocate over $675 billion in federal funds every year and it assists states, local communities, and businesses in making informed decisions. T ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
