Chapter 7 - Plate Boundaries Flashcards
Plate Tectonics
The theory that Earth’s outer crust (lithosphere) is divided into several plates.
Continental Crust
Layer of rock which forms the continents; floats on top part of the mantle (asthenosphere); older than oceanic crust, mostly granite rock; thicker and less dense than oceanic crust.
Oceanic crust
A thin layer of crust that underlies the ocean basins; younger than continental crust; more dense than continental crust.
Ring of Fire
Long chain of volcanoes that surrounds the Pacific Ocean; one of the most geologically active areas on Earth; site of frequent earthquakes and volcanic eruptions; caused by plate boundaries converging, diverging, and transforming.
Major Tectonic Plates
Pacific, South American, North American, Eurasian, African, Indo-Australian, Antarctic
Minor Tectonic Plates
Juan de Fuca, Nazca, Cocos, Caribbean, Arabian, Scotia, Arabian, Philippine, Indian
Divergent Plate Boundary
apart, dividing
Causes continental - rift valleys
Causes oceanic - sea floor spreading
Great Rift Valley in Africa, Mid-Atlantic Ridge in Atlantic Ocean
Transform Plate Boundary
Sliding past each other
Causes earthquakes, fault lines
The San Andreas Fault in California
Convergent Plate Boundary Collision
Colliding into each other
Causes mountain building
The Indo-Australian plate converges with the Eurasian plate to form the Himalayan Mountains
Convergent Plate Boundary Subduction: Ocean-Ocean
The older plate subducts under the newer one.
Causes volcanoes
Underwater volcanoes
Convergent Plate Boundary Subduction: Ocean-Continent
The more dense ocean plate subducts under the continental plate
Causes volcanoes
Above ground volcanoes in South America
Convection Currents
Transfers energy in the mantle; causes the hotter magma in the mantle to rise; causes the cooler magma in the mantle to sink; causes the plates to move.
