REVIEW - Sites of volcanism 1.Hot spots 2 Plate boundaries...

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Sites of volcanism: 1.Hot spots 2. Plate boundaries Balance between internal forces pushing crust outward and denudational processes that weather and erode the crust in landforms Intrusive igneous plutons are buried magma chambers that are solidified-typically granite Basaltic magma is only in oceanic crust, has a low viscosity (lava that flows easily), low gas content, low silica content, high melting temperature, forms lava and very little pyroclasitcs and has a nonviolent flow. Andesitic magma is in the oceanic and continental crust, has a high viscosity, high gas content, high silica content, low melting temperature, form lava and pyroclastics and has a violent eruption/flow. Shield Volcanoes and flood basalts contain basaltic magma. They don’t form mountains. They take thousands millions of years to form. Shallow slopes. Occur at island arcs, hot spots, and spreading centers. Flowing lava. All of the volcanoes in Hawaii are shield volcanoes. Cinder cones have the steepest slopes. Contain andesitic magma. They are small. Take thousands millions years to form. Fall back around vent to create a mound. Composite volcanoes are the typically volcano thought of. They have a steep slope but less than cinder cones, more than shield volcanoes. They also form a mound around eruption vent. Take thousands millions years to form. Occur at hot spots, spreading centers, and island arcs. Form from series of eruptions. Earthquakes are slippages along the fault, which leads to a rapid release of energy sudden vibration of the earth. Mainly convergence zones—and rim of fire. Tsunamis are underwater earthquakes. Regions of uplight/subsidence of ocean floor. Plates give way just like an earthquake. It’s an underwater landslide. Epicenter of an earthquake is above the focus. It is where the earthquake occurred but on the surface, not underneath the core. Tensional fault-normal fault. Hanging wall subsides. Most common Basin and range topography—characterized by horsts and grabens. Formed by normal/tensional faults. A Horst is an upfaulted block. A graben is a downfaulted block.
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Compressional fault is crustal shortening. A reverse fault—hanging wall rises. Ex: Appalachian Mtns. Shear stress/strike-slip fault is characterized by horizontal displacement. Such as the San Andreas Fault system. Also called a transverse fault. Anticline=upwarped fold, syncline=downwarped fold Mechanical/physical weathering- wearing/breaking down of rocks due to direct contact with the atmosphere such as heat, pressure, water, and ice. It occurs in cold moist environments. Characterized by freeze/thaw and exfoliation (pressure release) Chemical weathering is the breakdown through alternation of chemical composition of rock, such as limestone karst topography. Direct effect of atmospheric chemicals. Chemical weathering occurs in warm, wet environments such as tropical rain forests. Creates sinkholes, and underground streams and lakes. Limestone
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REVIEW - Sites of volcanism 1.Hot spots 2 Plate boundaries...

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