|
Scoria
Scoria is a pyroclastic, highly vesicular, dark-colored volcanic rock that was ejected from a volcano as a molten blob and cooled in the air to form discrete grains or clasts.Neuendorf, K.K.E., J.P. Mehl, Jr., and J.A. Jackson, eds. (2005) ''Glossary of Geology'' (5th ed.). Alexandria, Virginia, American Geological Institute. 779 pp. It is typically dark in color (generally dark brown, black or purplish-red), and basaltic or andesitic in composition. Scoria is relatively low in density as a result of its numerous macroscopic ellipsoidal vesicles, but in contrast to pumice, all scoria has a specific gravity greater than 1, and sinks in water. The holes or vesicles form when gases that were dissolved in the magma come out of solution as it erupts, creating bubbles in the molten rock, some of which are frozen in place as the rock cools and solidifies. Scoria may form as part of a lava flow, typically near its surface, or as fragmental ejecta (lapilli, blocks and bombs), for ins ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Scoria Macro Digon3
Scoria is a pyroclastic, highly vesicular, dark-colored volcanic rock that was ejected from a volcano as a molten blob and cooled in the air to form discrete grains or clasts.Neuendorf, K.K.E., J.P. Mehl, Jr., and J.A. Jackson, eds. (2005) ''Glossary of Geology'' (5th ed.). Alexandria, Virginia, American Geological Institute. 779 pp. It is typically dark in color (generally dark brown, black or purplish-red), and basaltic or andesitic in composition. Scoria is relatively low in density as a result of its numerous macroscopic ellipsoidal vesicles, but in contrast to pumice, all scoria has a specific gravity greater than 1, and sinks in water. The holes or vesicles form when gases that were dissolved in the magma come out of solution as it erupts, creating bubbles in the molten rock, some of which are frozen in place as the rock cools and solidifies. Scoria may form as part of a lava flow, typically near its surface, or as fragmental ejecta (lapilli, blocks and bombs), for ins ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Basalt
Basalt (; ) is an 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 surface of a rocky planet or 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 Venus, which cover ~80% of the surface, are basaltic; the 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 flows that can spread over great areas before cooling and solidifying. Flood basalts are t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cinder Cone
A cinder cone (or scoria cone) is a steep conical hill of loose pyroclastic fragments, such as volcanic clinkers, volcanic ash, or scoria that has been built around a volcanic vent. The pyroclastic fragments are formed by explosive eruptions or lava fountains from a single, typically cylindrical, vent. As the gas-charged lava is blown violently into the air, it breaks into small fragments that solidify and fall as either cinders, clinkers, or scoria around the vent to form a cone that often is symmetrical; with slopes between 30 and 40°; and a nearly circular ground plan. Most cinder cones have a bowl-shaped crater at the summit. Mechanics of eruption Cinder cones range in size from tens to hundreds of meters tall and often have a bowl-shaped crater at the summit. They are composed of loose pyroclastic material ( cinder or scoria), which distinguishes them from ''spatter cones'', which are composed of agglomerated volcanic bombs. The pyroclastic material making up a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pumice
Pumice (), called pumicite in its powdered or dust form, is a volcanic rock that consists of highly vesicular rough-textured volcanic glass, which may or may not contain crystals. It is typically light-colored. Scoria is another vesicular volcanic rock that differs from pumice in having larger vesicles, thicker vesicle walls, and being dark colored and denser.Jackson, J.A., J. Mehl, and K. Neuendorf (2005) ''Glossary of Geology'' American Geological Institute, Alexandria, Virginia. 800 pp. McPhie, J., M. Doyle, and R. Allen (1993) ''Volcanic Textures A guide to the interpretation of textures in volcanic rocks'' Centre for Ore Deposit and Exploration Studies, University of Tasmania, Hobart, Tasmania..198 pp. Pumice is created when super-heated, highly pressurized rock is violently ejected from a volcano. The unusual foamy configuration of pumice happens because of simultaneous rapid cooling and rapid depressurization. The depressurization creates bubbles by lowering the solu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Volcanic Rock
Volcanic rock (often shortened to volcanics in scientific contexts) is a rock formed from lava erupted from a volcano. In other words, it differs from other igneous rock by being of volcanic origin. Like all rock types, the concept of volcanic rock is artificial, and in nature volcanic rocks grade into hypabyssal and metamorphic rocks and constitute an important element of some sediments and sedimentary rocks. For these reasons, in geology, volcanics and shallow hypabyssal rocks are not always treated as distinct. In the context of Precambrian shield geology, the term "volcanic" is often applied to what are strictly metavolcanic rocks. Volcanic rocks and sediment that form from magma erupted into the air are called "volcaniclastics," and these are technically sedimentary rocks. Volcanic rocks are among the most common rock types on Earth's surface, particularly in the oceans. On land, they are very common at plate boundaries and in flood basalt provinces. It has been estimated ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mount Quincan
Mount Quincan is a volcanic mountain near Yungaburra on the Atherton Tableland in Far North Queensland, Australia. The extinct volcano is one of many cinder cones in the Atherton Tableland region. Its crater is approximately 500 m across, with the main cone being to the northwest. Several of the nearby Seven Sisters cinder cones also have their craters to the southeast, which is possibly due to the ash and scoria being blown to the northwest by the prevailing SE winds. Swamp deposits within the crater were dated at 7250 years old, making that the minimum age for Mt Quincan. The scoria deposits also contain abundant mantle xenoliths of peridotite. Quincan, a type of Scoria Scoria is a pyroclastic, highly vesicular, dark-colored volcanic rock that was ejected from a volcano as a molten blob and cooled in the air to form discrete grains or clasts.Neuendorf, K.K.E., J.P. Mehl, Jr., and J.A. Jackson, eds. (2005) '' ..., is mined from the south west quadrant of the mountain ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lapilli
Lapilli is a size classification of tephra, which is material that falls out of the air during a volcanic eruption or during some meteorite impacts. ''Lapilli'' (singular: ''lapillus'') is Latin for "little stones". By definition lapilli range from in diameter. A pyroclastic particle greater than 64 mm in diameter is known as a volcanic bomb when molten, or a volcanic block when solid. Pyroclastic material with particles less than 2 mm in diameter is referred to as volcanic ash. Formation Lapilli are spheroid-, teardrop-, dumbbell- or button-shaped droplets of molten or semi-molten lava ejected from a volcanic eruption that fall to earth while still at least partially molten. These granules are not accretionary, but instead the direct result of liquid rock cooling as it travels through the air. Lapilli tuffs are a very common form of volcanic rock typical of rhyolite, andesite and dacite pyroclastic eruptions, where thick layers of lapilli can be deposited durin ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Maungarei
Maungarei (officially known as Maungarei / Mount Wellington) is a 135-metre volcanic peak and Tūpuna Maunga (ancestral mountain) located in the Auckland volcanic field of Auckland, New Zealand. It is the youngest onshore volcano of the Auckland volcanic field, having been formed by an eruption around 10,000 years ago. It is the largest of Auckland's scoria cones and has a near-circular base with a flattish rim and three small craters. It is situated in the Mount Wellington suburb of East Auckland. Geology A number of lava flows were created by the mountain's eruption, including one which was six kilometres in length, stretching to the Manukau Harbour at Southdown. Another lava flow blocked the course of a river valley, forming Lake Waiatarua. History The name is short for Te Maungarei ā Pōtaka, the ancient Ngāi Tai ki Tāmaki / Te Waiōhua chief whose domain included the mountain and surrounding areas. Maungarei is also translated as "the watchful mountain" or " ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pyroclastic
Pyroclastic rocks (derived from the el, πῦρ, links=no, meaning fire; and , meaning broken) are clastic rocks composed of rock fragments produced and ejected by explosive volcanic eruptions. The individual rock fragments are known as pyroclasts. Pyroclastic rocks are a type of volcaniclastic deposit, which are deposits made predominantly of volcanic particles. 'Phreatic' pyroclastic deposits are a variety of pyroclastic rock that forms from volcanic steam explosions and they are entirely made of accidental clasts. 'Phreatomagmatic' pyroclastic deposits are formed from explosive interaction of magma with groundwater. Unconsolidated accumulations of pyroclasts are described as tephra. Tephra may become lithified to a pyroclastic rock by cementation or chemical reactions as the result of the passage of hot gases (fumarolic alteration) or groundwater (e.g. hydrothermal alteration and diagenesis) and burial, or, if it is emplaced at temperatures so hot that the soft glassy p ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Australia
Australia, officially the Commonwealth of Australia, is a sovereign country comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands. With an area of , Australia is the largest country by area in Oceania and the world's sixth-largest country. Australia is the oldest, flattest, and driest inhabited continent, with the least fertile soils. It is a megadiverse country, and its size gives it a wide variety of landscapes and climates, with deserts in the centre, tropical rainforests in the north-east, and mountain ranges in the south-east. The ancestors of Aboriginal Australians began arriving from south east Asia approximately 65,000 years ago, during the last ice age.religious_traditions_in_the_world._Australia's_history_of_Australia.html" "title="The_Dreaming.html" ;"title="Aboriginal_Art.html" "title="he Story of Australia's People, Volume 1: The Rise and Fall of Ancient Australia, Penguin Books Australia Ltd., Vic. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Far North Queensland
Far North Queensland (FNQ) is the northernmost part of the Australian state of Queensland. Its largest city is Cairns and it is dominated geographically by Cape York Peninsula, which stretches north to the Torres Strait, and west to the Gulf Country. The waters of Torres Strait include the only international border in the area contiguous with the Australian mainland, between Australia and Papua New Guinea. The region is home to three World Heritage Sites, the Great Barrier Reef, the Wet Tropics of Queensland and Riversleigh, Australia's largest fossil mammal site. Far North Queensland lays claim to over 70 national parks, including Mount Bartle Frere; with a peak of it is the highest peak in both Northern Australia and Queensland. The Far North region is the only region of Australia that is the indigenous country of both Aboriginal Australians and Torres Strait Islanders. Far North Queensland supports a significant agricultural sector, a number of significant mines and i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
