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Gumdrop Seamount
Gumdrop Seamount is a small seamount ( underwater volcano) located on the flank of Pioneer Seamount, off the coast of Central California. It is the northernmost of the related seamounts in the region, which includes Davidson, Guide, Pioneer, and Rodriguez seamounts. It is defined by a series of aligned cones, the majority of which are poorly defined, separated by troughs filled with sediments. The largest cone rises to within of sea level. It is estimated to have a volume of about , but the poorly defined base hinders observations of its size. Samples recovered from Gumdrop are highly vesicular in origin, and include alkalic basalt, hawaiite, and mugearite Mugearite () is a type of oligoclase-bearing basalt, comprising olivine, apatite, and opaque oxides. The main feldspar in mugearite is oligoclase. Mugearite is a sodium-rich member of the alkaline magma series. In the TAS classification of volc ...; however, their ages have yet to be determined. References Seamounts ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Central California
Central California is generally thought of as the middle third of the state, north of Southern California, which includes Los Angeles, and south of Northern California, which includes San Francisco. It includes the northern portion of the San Joaquin Valley (which itself is the southern portion of the Central Valley, beginning at the Sacramento–San Joaquin River Delta), part of the Central Coast, the central hills of the California Coast Ranges and the foothills and mountain areas of the central Sierra Nevada. Central California is considered to be west of the crest of the Sierra Nevada. East of the Sierra is Eastern California. The largest cities in the region (over 50,000 population), from most to least populous, are Fresno, Bakersfield, Stockton, Modesto, Salinas, Visalia, Clovis, Santa Maria, Merced, Turlock, Madera, Lodi, Tulare, Porterville, Hanford and Delano. Over time, droughts and wildfires have increased in frequency and become less seasonal and more y ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Guide Seamount
Guide Seamount is a seamount in the eastern Pacific Ocean, about 16.6 ±0.5 million years old. It is similar in shape and orientation to the nearby Davidson, Pioneer, Rodriguez, and Gumdrop seamounts. It is named for the United States Coast and Geodetic Survey survey ship ''USC&GS Guide''. Guide Seamount is constructed of four nearly parallel volcanic ridges, separated by sediment-filled throughs. These are aligned parallel to magnetic anomalies in the underlying oceanic crust. It is very similar in shape and structure to the nearby Davidson Seamount, except that it is smaller, at approximately by . It rises about above the seafloor and sits at depth of . The lavas from Guide are mostly alkalic basalt, hawaiite, mugearite with some pyroclastic flow A pyroclastic flow (also known as a pyroclastic density current or a pyroclastic cloud) is a fast-moving current of hot gas and volcanic matter (collectively known as tephra) that flows along the ground away from a volcano at av ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hawaiite
Hawaiite is an olivine basalt with a composition between alkali basalt and mugearite. It was first used as a name for some lavas found on the island of Hawaii. It occurs during the later stages of volcanic activity on oceanic islands such as Hawaii, which happens to be when the alkaline metals are most present. In gemology, hawaiite is a colloquial term for Hawaii-originated peridot, which is a gem-quality form of the mineral olivine. Description Hawaiite is an aphanitic (fine-grained) volcanic rock produced by rapid cooling of lava moderately poor in silica and enriched in alkali metal oxides (potassium oxide plus sodium oxide). It is often impractical to determine the mineral composition of such a fine-grained rock, and so hawaiite is defined chemically. Under the TAS classification, hawaiite is sodic trachybasalt, with a silica content close to 49 wt%, a total alkali metal oxide content close to 6%, and wt% > wt% + 2. This places hawaiite in the S1 field of the TAS dia ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Basalt
Basalt (; ) is an aphanite, aphanitic (fine-grained) extrusive igneous rock formed from the rapid cooling of low-viscosity lava rich in magnesium and iron (mafic lava) exposed at or very near the planetary surface, surface of a terrestrial planet, rocky planet or natural satellite, moon. More than 90% of all volcanic rock on Earth is basalt. Rapid-cooling, fine-grained basalt is chemically equivalent to slow-cooling, coarse-grained gabbro. The eruption of basalt lava is observed by geologists at about 20 volcanoes per year. Basalt is also an important rock type on other planetary bodies in the Solar System. For example, the bulk of the plains of volcanism on Venus, Venus, which cover ~80% of the surface, are basaltic; the lunar mare, lunar maria are plains of flood-basaltic lava flows; and basalt is a common rock on the surface of Mars. Molten basalt lava has a low viscosity due to its relatively low silica content (between 45% and 52%), resulting in rapidly moving lava flo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Vesicular Texture
Vesicular texture is a volcanic rock texture characterized by a rock being pitted with many cavities (known as vesicles) at its surface and inside. This texture is common in aphanitic, or glassy, igneous rocks that have come to the surface of the earth, a process known as extrusion. As magma rises to the surface the pressure on it decreases. When this happens gasses dissolved in the magma are able to come out of solution, forming gas bubbles (the cavities) inside it. When the magma finally reaches the surface as lava and cools, the rock solidifies around the gas bubbles and traps them inside, preserving them as holes filled with gas called vesicles. A related texture is amygdaloidal in which the volcanic rock, usually basalt or andesite, has cavities, or vesicles, that are filled with secondary minerals, such as zeolites, calcite, quartz, or chalcedony. Individual cavity fillings are termed amygdules (American usage) or amygdales (British usage). Sometimes these can be source ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sea Level
Mean sea level (MSL, often shortened to sea level) is an average surface level of one or more among Earth's coastal bodies of water from which heights such as elevation may be measured. The global MSL is a type of vertical datuma standardised geodetic datumthat is used, for example, as a chart datum in cartography and marine navigation, or, in aviation, as the standard sea level at which atmospheric pressure is measured to calibrate altitude and, consequently, aircraft flight levels. A common and relatively straightforward mean sea-level standard is instead the midpoint between a mean low and mean high tide at a particular location. Sea levels can be affected by many factors and are known to have varied greatly over geological time scales. Current sea level rise is mainly caused by human-induced climate change. When temperatures rise, Glacier, mountain glaciers and the Ice sheet, polar ice caps melt, increasing the amount of water in water bodies. Because most of human settlem ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Rodriguez Seamount
Rodriguez Seamount is a seamount and guyot located about off the coast of Central California. It is structurally similar to the nearby Guide, Pioneer, Gumdrop, and Davidson seamounts, all located roughly between 37.5° and 34.0° degrees of latitude. This group of seamounts is morphologically unique, and the mounts are very similar to one another. The seamount structures run parallel to an ancient spreading center which has since been replaced in its role by the San Andreas Fault system. Geology Magnetic anomalies at Rodriguez indicate that it is located on a 19-million-year-old crustal surface. Rocks recovered from Rodriguez Seamount are largely composed of alkaline basalt and Hawaiite. Ar-Ar dating techniques indicate that the volcano is between 10 and 12 million years of age. Rodriguez Seamount rises about above the surrounding seafloor, to a minimum depth of . Its calculated volume is greater than ; however this is likely an understatement because the survey did not incl ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pioneer Seamount
Pioneer Seamount is an undersea mountain, or seamount, in the Pacific Ocean off the coast of central California. Location Pioneer Seamount is located at 37° 21.1' North Latitude, 123° 26.1' West Longitude, at the base of the continental slope of North America about off the coast just southwest of San Francisco, California. Physical characteristics The seamount is a volcano between 10.9 and 11.1 million years old. It is about long as well as about wide, and has a volume of about . It rises about above the surrounding ocean floor, and its peak is a minimum of below the oceans surface. Samples from the seamount consist of highly vesicular alkalic basalt, hawaiite, and mugearite. The seamount and its volcano once extended above the sea surface, but eroded and sank as the seamount and the seabed at its base were carried further away from the spreading center from which it presumably originated. Biological environment A wide variety of sealife lives on the seamount. Corals ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Davidson Seamount
Davidson Seamount is a seamount ( underwater volcano) located off the coast of Central California, southwest of Monterey and west of San Simeon. At long and wide, it is one of the largest known seamounts in the world. From base to crest, the seamount is tall, yet its summit is still below the sea surface. The seamount is biologically diverse, with 237 species and 27 types of deep-sea coral having been identified. Discovered during the mapping of California's coast in 1933, Davidson Seamount is named after geographer George Davidson of the United States Coast and Geodetic Survey. Studied only sparsely for decades, NOAA expeditions to the seamount in 2002 and 2006 cast light upon its unique deep-sea coral ecosystem. Davidson Seamount is populated by a dense population of large, ancient corals, some of which are over 100 years of age. The data gathered during the studies fueled the making of Davidson Seamount into a part of the Monterey Bay National Marine Sanctuary in 200 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Seamount
A seamount is a large geologic landform that rises from the ocean floor that does not reach to the water's surface (sea level), and thus is not an island, islet or cliff-rock. Seamounts are typically formed from extinct volcanoes that rise abruptly and are usually found rising from the seafloor to in height. They are defined by oceanographers as independent features that rise to at least above the seafloor, characteristically of conical form.IHO, 2008. Standardization of Undersea Feature Names: Guidelines Proposal form Terminology, 4th ed. International Hydrographic Organization and Intergovernmental Oceanographic Commission, Monaco. The peaks are often found hundreds to thousands of meters below the surface, and are therefore considered to be within the deep sea. During their evolution over geologic time, the largest seamounts may reach the sea surface where wave action erodes the summit to form a flat surface. After they have subsided and sunk below the sea surface such flat ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cental California
The hundredweight (abbreviation: cwt), formerly also known as the centum weight or quintal, is a British imperial and US customary unit of weight or mass. Its value differs between the US and British imperial systems. The two values are distinguished in American English as the "short" and "long" hundredweight and in British English as the "cental" and the "imperial hundredweight". * The short hundredweight or cental of is used in the United States. * The long or imperial hundredweight of 8 stone or is defined in the imperial system. Under both conventions, there are 20 hundredweight in a ton, producing a "short ton" of 2,000 pounds and a " long ton" of 2,240 pounds. History The hundredweight has had many values. In England in around 1300, different "hundreds" (''centum'' in Medieval Latin) were defined. The Weights and Measures Act 1835 formally established the present imperial hundredweight of 112 lb. The United States and Canada came to use the term ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
