Chapter 4 (1) - Chapter 4 What do we mean by plate...

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Chapter 4 What do we mean by plate tectonics? Lithosphere: consists of the crust and the uppermost and coolest part of the upper mantle. It is rather elastic and does not flow, it bends, breaks, or flexes Asthenosphere: the warmer mantle that can flow when acted on by force Broken pieces of the lithosphere are called plates, the breaks are called plate boundaries Active margins: plate boundaries Passive margins: not plate boundaries Along passive margins, continental crust is thinner than normal. Thick layers of sediment cover this thinned crust. The surface of this sediment layer is a broad, shallow region called the continental shelf The basic premise of plate tectonics As plates move, their internal area remains largely rigid and intact but rocks along the plate's boundaries undergo deformation as the plate grinds or scrapes against its neighbors or pulls away from them Identifying plate boundaries Earthquake belts define the position of plate boundaries because the fracturing and slipping that occur along plate boundaries as plates move generate earthquakes. Geologists define three types of plate boundaries. o Divergent boundary: a boundary at which two plates move apart from one another o Convergent boundary: A boundary at which two plates move toward one another so that one plate sinks beneath the other o Transform boundary: A boundary at which one plate slips along the side of another plate Divergent plate boundaries and sea-floor spreading
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This note was uploaded on 02/01/2012 for the course GEOLOGY 100 taught by Professor Lepre during the Fall '11 term at Rutgers.

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Chapter 4 (1) - Chapter 4 What do we mean by plate...

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