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Plate Boundaries. Chapter 17.3. Theory of Plate Tectonics the idea that the Earth’s crust is divided into several large sections that move very slowly over the Earth’s mantle. Plate Boundaries 1. Divergent Boundary – a region where two plates are moving apart.
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Plate Boundaries Chapter 17.3
Theory of Plate Tectonics • the idea that the Earth’s crust is divided into several large sections that move very slowly over the Earth’s mantle. Plate Boundaries 1. Divergent Boundary – a region where two plates are moving apart. - magma rises from the mantle to fill the void (crack) as the plates move apart. - forms a “rift valley” Video – Introduction to Plate Tectonics (2:21 min)
2. Convergent Boundary – two plates are moving toward each other. a. Oceanic-Oceanic – one plate is subducted beneath another. - creates an ocean trench and a volcanic island arc.
b. Oceanic-Continental – the oceanic plate is subducted beneath the continental plate. - creates an ocean trench and a volcanic mountain range on the continent.
c. Continental-Continental – two continental plates push against each other causing them to “buckle-upward”. - creates inner-continental mountain range.
3. Transform Boundaries – two plates slide past each other horizontally. - creates long faults and shallow earthquakes.
