several reasons that influence volcanic hazards‚ these include the viscosity of the magma‚ proximity to population centres‚ materials that are ejected from the volcano‚ the magnitude of the eruption and the plate margin that the volcano rests upon. The viscosity of the magma depends on 3 things‚ the temperature‚ dissolved gasses and the chemistry involved in the magma. These factors produce 2 main types of magma called acid and basic. The acid lava is the more viscous (66%+ rich silica) and so this
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Intrusive: Batholith: A large emplacement of igneous plutonic rock‚ formed by magma cooling deep in the Earth’s crust. Buoyant magma pushes up through the country rock‚ partially melting it‚ and then cools. A good example is the Cornubian batholith in south-west England‚ which has broken through the surface to form the well-known granite structures of Dartmoor and Bodmin moor‚ among others. Sill: A tabular sheet intrusion where magma has intruded between older layers of sedimentary rock‚ beds of volcanic
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This partial melting produces magma chambers above the subducting oceanic plate. These magma chambers are less dense than the surrounding mantle materials and are buoyant. The buoyant magma chambers begin a slow ascent through the overlying materials‚ melting and fracturing their way upwards. The size and depth of these magma chambers can be determined by mapping the earthquake activity around them. If a magma chamber rises to the surface without solidifying‚ the magma will break through in the form
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solidified. They can form underground or above ground. Underground‚ they are formed when the melted rock‚ called magma‚ deep within the earth becomes trapped in small pockets. As these pockets of magma cool slowly underground‚ the magma becomes igneous rocks. Igneous rocks also form when volcanoes erupt‚ causing the magma to rise above the earths surface‚ above the earths surface magma is called lava. The rocks are formed as the lava cools. Sedimentary rocks are formed at the surface of the
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The Rock Cycle & Classification of Rocks The rock cycle is the formation‚ breakdown and reformation of a rock as a result of sedimentary‚ igneous‚ and metamorphic processes. The rock cycle is an illustration that is used to describe how the three rock types are related and how Earth processes change a rock from one type to another over time. Each group contains a collection of rock types that differ from each other on the basis of the size‚ shape and arrangement of mineral grains. Due to the driving
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completion to the rock cycle; however‚ it may be appropriate to begin investigating the rock cycle with magma (Bergman 2005). Magma‚ or molten rock‚ forms only at certain locations within the earth‚ mostly along plate boundaries. Magma crystallizes when it is permitted to cool. Most magma never makes it to the surface and it cools inside the earth’s crust. Igneous rocks are formed from cooled magma. If magma cools below the earth’s surface it forms intrusive igneous rocks (gabbro); if it cools above the
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cooling of magma True Density differences can force magma upward into cooler layers of Earth’s interior True If magma cools slowly‚ atoms do not have time to arrange themselves into larger crystals False Small crystals form rapidly cooling magma True When liquid evaporrates from a soluation‚ the remaining elements cannot form crystals False Minerals can form elements dissolved in a solution True If a solution remains unsaturated‚ mineral crystals may precipitate False Magma is often a
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Volcanic Landforms Volcano is essentially a fissure or vent (opening) which serves as an outlet for hot magma from beneath the Earth’s crust. The hot liquid magma coming out in the form of lava (most commonly molten basalt) is potential of shaping different landforms on earth crust. The most common landforms that are results of volcanic activity include cones‚ craters‚ calderas‚ domes etc. This article gives a description of these volcanic landforms. SHIELD VOLCANOES- These are characterised
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SCI/245 Robert Dillon Write a 500- to 750-word explanation regarding the role of plate tectonics in the origin of igneous rocks. The role of plate tectonics in the origin of igneous rock is extremely important. Igneous rock is formed from magma that reaches the continental and oceanic crust or through hot spots that are around the world. There are three different places where igneous rocks can form; where the lithospheric plates pull apart at mid ocean ridges‚ where plates come together at
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heat energy produced from radioactive decay in the earth’s core. As the convection currents move the plates away from each other‚ there is a weaker zone in the crust and an increase in heat near the surface. The hotter‚ expanded crust forms a ridge. Magma rises up from the mantle in the gap. The lava cools‚ solidifies and forms a chain of volcanic mountains thousands of miles long down the middle of the ocean eg. Atlantic. There are transform faults at right angles to the ridge. The movement of these
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