Lect 20 Geology and Earth Resources

Lect 20 Geology and Earth Resources - Geology and Earth...

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Geology and Earth Resources A DYNAMIC PLANET A Layered Sphere Core - Interior composed of dense, intensely hot metal. Generates magnetic field enveloping the earth. Mantle - Hot, pliable layer surrounding the core. Less dense than core. Crust - Cool, lightweight, brittle outermost layer. Floats on top of mantle. Earth’s Cross Section Plate tectonic theory The prevailing theory in geology is the theory of plate tectonics Remember, a theory in science is not the everyday “theory” in common usage. It is a powerful statement. This theory can explain the formation of landforms, and the processes that have been at work to form them…. Earthquakes, volcanoes, mountain building, seafloor formation, continental movement…. . Tectonic Processes Upper layer of mantle contains convection currents that break overlaying crust into a mosaic of tectonic plates. Slide slowly across earth’s surface. Ocean basins form where continents crack and pull apart. Magma forced up through cracks in oceanic crust form mid-oceanic ridges. Tectonic Plates Tectonic Processes Earthquakes are caused by grinding and jerking as plates slide past each other. Earthquakes Stress can deform rock in Earth’s crust Too much stress builds up and the rock fractures, and maybe shifts, producing a fault Movement along a fault is an earthquake During the shift or movement a great amount of energy is released as shock waves which move outward from the origin of movement Focus Epicenter Magnitude measures the intensity of the earthquake, or the amount of energy that is released. Magnitude measures the intensity of the earthquake, or the amount of energy that is released. Richter scale (logarithmic) Aftershocks Primary effects Displacement of crust Shaking
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Secondary effects Rockslides, urban fires, flooding through subsidence. Tsunami - Seismic sea swells Tectonic Processes Earthquakes are caused by grinding and jerking as plates slide past each other. Mountain ranges pushed up at the margins of colliding plates. When an oceanic plate collides with a continental landmass, the continental plate will ride up over the seafloor and the oceanic plate will subduct down into the mantle. Deep ocean trenches mark subduction zones.
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This note was uploaded on 04/26/2008 for the course BIOLOGY 118 taught by Professor Richardson during the Spring '08 term at Winona.

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Lect 20 Geology and Earth Resources - Geology and Earth...

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