continental drift & pangaea

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CONTINENTAL DRIFT & PANGAEA. In 1912, Alfred Wegener proposed the idea that the continents were once part of a huge land mass, called Pangaea (all lands), that later broke apart. He was convinced because:. 1. the continent’s shape roughly fit together like a puzzle. - PowerPoint PPT Presentation

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Ch. 7

Plate Tectonic movement shapes the EarthPlate tectonics = process that underlies earthquakes and volcanoes and that determines the geography of the Earths surfaceEarths crust and upper mantle are separated into lithospheric plates that move in different directions and at different ratesCrust = lightweight thin component of Earths surfaceMantle = malleable layer on which the crust floats composed of silica and magnesium oxidesCore = molten heavy center of Earth made mostly of iron and nickel

Plate Tectonics Video Copyright 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings11The Earth has 15 major tectonic plates

Movement of these plates influences climate and evolutionCopyright 2008 Pearson Education, Inc., publishing as Pearson Benjamin CummingsPangaea: the supercontinentPangaea = at least twice (probably more) in Earths history, all landmasses were joined in one supercontinent

Copyright 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings33Earths crust is constantly created and destroyedDivergent plate boundaries = magma surging upward to the surface divides plates and pushes them apart, creating new crust as it cools and spreads Transform plate boundary = two plates meet, slipping and grinding alongside one anotherFriction spawns earthquakes along slip-strike faults

Copyright 2008 Pearson Education, Inc., publishing as Pearson Benjamin CummingsTectonic plates can collideConvergent plate boundaries = where plates collideSubduction = one plate of crust may slide beneath anotherMagma erupts through the surface in volcanoesTwo colliding plates of continental crust may lift material from both platesResulted in the Himalaya and Appalachian mountains

Copyright 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings55

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