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| Volcanic ash consists of small tephra, which are bits of pulverized rock and glass created by volcanic eruptions,[1] less than 2 millimetres (0.079 in) in diameter. |
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composite or strato-volcano [image] |
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| A stratovolcano, sometimes inappropriately called a composite volcano, is a tall, conical volcano with many layers (strata) of hardened lava, tephra, and volcanic ash. |
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A joint is the location at which two or more lava make contact.[1] They are constructed to allow movement and provide mechanical support, and are classified structurally and functionally.[2] |
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| Magma (Plurals include: magmas and magmata) is molten rock that is found beneath the surface of the Earth, and may also exist on other terrestrial planets. |
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| In geology, a sill is a tabular pluton that has intruded between older layers of sedimentary rock, beds of volcanic lava or tuff, or even along the direction of foliation in metamorphic rock. |
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A batholith (from Greek bathos, depth + lithos, rock) is a large emplacement of igneous intrusive (also called plutonic) rock that forms from cooled magma deep in the Earth's crust. Batholiths are almost always made mostly of felsic or intermediate rock-types, such as granite, quartz monzonite, or diorite (see also granite dome). |
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A dike or dyke in geology is a type of sheet intrusion referring to any geologic body that cuts discordantly across planar wall rock structures, such as bedding or foliation massive rock formations, like igneous/magmatic intrusions and salt diapirs. |
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A laccolith is an igneous intrusion (or concordant pluton) that has been injected between two layers of sedimentary rock. The pressure of the magma is high enough that the overlying strata are forced upward, giving the laccolith a dome or mushroom-like form with a generally planar base. |
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Olympus Mons (Latin for "Mount Olympus") is the tallest known volcano and mountain in the Solar System. It is located on the planet Mars at approximately 18°N 133°W / 18, -133. It is three times higher than Mount Everest. Since the late 19th century — well before space probes confirmed its identity as a mountain — Olympus Mons was known to astronomers as the albedo feature, Nix Olympica ("Snows of Olympus"), although its mountainous nature was suspected.[1] |
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| stock means a share of ownership in a corporation. In the plural, stocks is often used as a synonym for shares especially in the United States, but it is less commonly used that way outside of North America.[1] |
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| A linear mountain that is bounded on both sides by normal faults |
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| A term used to describe an igneous rock that has a large percentage of light-colored minerals such as quartz, feldspar, and muscovite. Also used in reference to the magmas from which these rocks crystallize. Felsic rocks are generally rich in silicon and aluminum and contain only small amounts of magnesium and iron. Granite and rhyolite are examples of felsic rocks. (See mafic to contrast.) |
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| Volcanic rock materials which are formed when magma is ejected by a volcano. Typically used for material that ranges between 2 and 64 millimeters in diameter. |
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| A specific event in the history of Earth's magnetic field. Usually used in reference to a specific polarity reversal. |
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subduction eruption [image] |
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| A type of volcanic eruption characterized by fountains of lava jetting from a lava-filled central crater. |
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| A volcanic bomb is a globe of molten rock (tephra) larger than 65 mm (2.5 inches) in diameter, formed when a volcano ejects viscous fragments of lava during an eruption. They cool into solid fragments before they reach the ground. |
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| In geology, a hotspot is a location on the Earth's surface that has experienced active volcanism for a long period of time. J. Tuzo Wilson came up with the idea in 1963 that volcanic chains like the Hawaiian Islands result from the slow movement of a tectonic plate across a "fixed" hot spot deep beneath the surface of the planet. |
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| Lava is molten rock expelled by a volcano during an eruption. When first expelled from a volcanic vent, it is a liquid at temperatures from 700 °C to 1,200 °C (1,300 °F to 2,200 °F). Although lava is quite viscous, with about 100,000 times the viscosity of water, it can flow great distances before cooling and solidifying, |
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| Pyroclastic rocks or pyroclastics (derived from the Greek πῦρ, meaning fire, and κλαστός, meaning broken) are clastic rocks composed solely or primarily of volcanic materials. Where the volcanic material has been transported and reworked through mechanical action, such as by wind or water, these rocks are termed volcaniclastic. |
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Tephra is air-fall material produced by a volcanic eruption regardless of composition or fragment size.[1] Tephra is typically rhyolitic in composition, as most explosive volcanoes are the product of the more viscous felsic or high silica magmas. |
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A cinder cone or scoria cone is a steep conical hill of volcanic fragments that accumulate around and downwind from a volcanic vent.[1] The rock fragments, often called cinders or scoria, are glassy and contain numerous gas bubbles "frozen" into place as magma exploded into the air and then cooled quickly.[1] Cinder cones range in size from tens to hundreds of meters tall.[1] Cinder cones are made of pyroclastic material. |
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| A rich accumulation of minerals in solid rock. Frequently in the form of a vein, layer or an area with a large concentration of disseminated particles |
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A lopolith is a large igneous intrusion which is lenticular in shape with a depressed central region. Lopoliths are generally concordant with the intruded strata with dike or funnel-shaped feeder bodies below the body. The term was first defined and used by Frank Fitch Grout during the early 1900s in describing the Duluth gabbro complex in northern Minnesota and adjacent Ontario. |
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| The east rift zone extends 52 km (31 miles) east-northeast from the summit to Cape Kumukahi and another 75 km (45 miles) to the eastern tip of the submarine Puna Ridge. It consists of eruptive fissures, ground cracks, stored bodies of solidified or molten magma, and a conduit system that carries magma from the summit reservoir |
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A volcanic plug, also called a volcanic neck or lava neck, is a volcanic landform created when magma hardens within a vent on an active volcano. When forming, a plug can cause an extreme build-up of pressure if volatile-charged magma is trapped beneath it, and this can sometimes lead to an explosive eruption. If a plug is preserved, erosion may remove the surrounding rock while the erosion-resistant plug remains, producing a distinctive landform. |
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| During the cooling of a thick lava flow, contractional joints or fractures form. If a flow cools relatively rapidly, significant contraction forces build up. |
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Mafic is an adjective describing a silicate mineral or rock that is rich in magnesium and iron; the term was derived by contracting "magnesium" and "ferric". Most mafic minerals are dark in color and the specific gravity is greater than 3. Common rock-forming mafic minerals include olivine, pyroxene, amphibole, and biotite. Common mafic rocks include basalt and gabbro. |
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A shield volcano is a large volcano with shallow-sloping sides. The name derives from a translation of "Skjaldbreiður", an Icelandic shield volcano whose name means "broad shield", from its resemblance to a warrior's shield. |
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| A volcano is an opening, or rupture, in a planet's surface or crust, which allows hot, molten rock, ash, and gases to escape from below the surface. Volcanic activity involving the extrusion of rock tends to form mountains or features like mountains over a period of time. |
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