Plate Tectonics 1.1 Earth has several layers. 1.2 CHAPTER Plate Tectonics the BIG idea The movement of tectonic plates causes geologic changes on Earth. 1.1 Earth has several layers. 1.2 Continents change position over time. 1.3 Plates move apart. 1.4 Plates converge or scrape past each other. CHAPTER OUTLINE

Earth has several layers. 1.1 Earth has several layers. inner core lithosphere outer core crust mantle crust mantle lithosphere asthenosphere outer core asthenosphere inner core tectonic plate The lithosphere is made up of tectonic plates, which rest on the asthenosphere. SECTION OUTLINE

1.1 inner core Earth has several layers. outer core A solid sphere of metal, mainly nickel and iron, at Earth’s center. mantle crust lithosphere asthenosphere tectonic plate KEY CONCEPT SUMMARY

1.1 outer core Earth has several layers. inner core outer core outer core A layer of molten metal, mainly nickel and iron, that surrounds Earth’s inner core. mantle crust lithosphere asthenosphere tectonic plate KEY CONCEPT SUMMARY

1.1 mantle Earth has several layers. inner core mantle outer core The layer of rock between Earth’s outer core and crust, in which most rock is hot enough to flow in convection currents; Earth’s thickest layer. mantle crust lithosphere asthenosphere tectonic plate KEY CONCEPT SUMMARY

1.1 crust Earth has several layers. inner core crust outer core A thin outer layer of rock above a planet’s mantle, including all dry land and ocean basins. Earth’s continental crust is 40 kilometers thick on average and oceanic crust is 7 kilometers thick on average. mantle crust lithosphere asthenosphere tectonic plate KEY CONCEPT SUMMARY

1.1 lithosphere Earth has several layers. inner core lithosphere outer core The layer of Earth made up of the crust and the rigid rock of the upper mantle, averaging about 40 kilometers thick and broken into tectonic plates. mantle crust lithosphere asthenosphere tectonic plate KEY CONCEPT SUMMARY

1.1 asthenosphere Earth has several layers. inner core asthenosphere outer core The layer in Earth’s upper mantle and directly under the lithosphere in which rock is soft and weak because it is close to melting. mantle crust lithosphere asthenosphere tectonic plate KEY CONCEPT SUMMARY

1.1 tectonic plate Earth has several layers. inner core tectonic plate outer core One of the large, moving pieces into which Earth’s lithosphere is broken and which commonly carries both oceanic and continental crust. mantle crust lithosphere asthenosphere tectonic plate KEY CONCEPT SUMMARY

Continents change position over time. 1.2 Continents change position over time. Gravity and motions in the asthenosphere move tectonic plates over Earth’s surface. continental drift Pangaea Earth’s tectonic plates. Arrows indicatethe direction of movement. mid-ocean ridge convection convection current theory of plate tectonics SECTION OUTLINE

1.2 continental drift Continents change position over time. Pangaea The hypothesis that Earth’s continents move on Earth’s surface. mid-ocean ridge convection convection current theory of plate tectonics KEY CONCEPT SUMMARY

1.2 Pangaea Continents change position over time. continental drift Pangaea Pangaea A hypothetical supercontinent that included all of the landmasses on Earth. It began breaking apart about 200 million years ago. mid-ocean ridge convection convection current theory of plate tectonics KEY CONCEPT SUMMARY

1.2 mid-ocean ridge Continents change position over time. continental drift mid-ocean ridge Pangaea A long line of sea-floor mountains where new ocean crust is formed by volcanic activity along a divergent boundary. mid-ocean ridge convection convection current theory of plate tectonics KEY CONCEPT SUMMARY

1.2 convection Continents change position over time. continental drift convection Pangaea A process by which energy is transferred in gases and liquids, occurring when a warmer, less dense area of gas or liquid is pushed up by a cooler, more dense area of the gas or liquid. mid-ocean ridge convection convection current theory of plate tectonics KEY CONCEPT SUMMARY

1.2 convection current Continents change position over time. continental drift convection current Pangaea A circulation pattern in which material is heated and rises in one area, then cools and sinks in another area, flowing in a continuous loop. mid-ocean ridge convection convection current theory of plate tectonics KEY CONCEPT SUMMARY

theory of plate tectonics 1.2 Continents change position over time. continental drift theory of plate tectonics Pangaea A theory stating that Earth’s lithosphere is broken into huge plates that move and change in size over time. mid-ocean ridge convection convection current theory of plate tectonics KEY CONCEPT SUMMARY

1.3 Plates move apart. New crust is formed at divergent boundaries. Features include: divergent boundary • mid-ocean ridges convergent boundary transform boundary rift valley magnetic reversal hot spot SECTION OUTLINE

1.3 Plates move apart. New crust is formed at divergent boundaries. Features include: divergent boundary • mid-ocean ridges • records of magnetic reversals convergent boundary transform boundary rift valley magnetic reversal hot spot SECTION OUTLINE

1.3 Plates move apart. New crust is formed at divergent boundaries. Features include: divergent boundary • mid-ocean ridges • records of magnetic reversals convergent boundary • rift valleys transform boundary rift valley magnetic reversal hot spot SECTION OUTLINE

1.3 divergent boundary Plates move apart. convergent boundary A boundary along which two tectonic plates move apart, characterized by either a mid- ocean ridge or a continental rift valley. transform boundary rift valley magnetic reversal hot spot KEY CONCEPT SUMMARY

1.3 convergent boundary Plates move apart. divergent boundary convergent boundary convergent boundary A boundary along which two tectonic plates push together, characterized either by subduction or a continental collision. transform boundary rift valley magnetic reversal hot spot KEY CONCEPT SUMMARY

1.3 transform boundary Plates move apart. divergent boundary transform boundary convergent boundary A boundary along which two tectonic plates scrape past each other, and crust is neither formed nor destroyed. transform boundary rift valley magnetic reversal hot spot KEY CONCEPT SUMMARY

1.3 rift valley Plates move apart. divergent boundary rift valley convergent boundary A deep valley formed as tectonic plates move apart, such as along a mid-ocean ridge. transform boundary rift valley magnetic reversal hot spot KEY CONCEPT SUMMARY

1.3 magnetic reversal Plates move apart. divergent boundary magnetic reversal convergent boundary A switch in the direction of Earth’s magnetic field so that the magnetic north pole becomes the magnetic south pole and the magnetic south pole becomes the magnetic north pole. transform boundary rift valley magnetic reversal hot spot KEY CONCEPT SUMMARY

1.3 hot spot Plates move apart. divergent boundary hot spot convergent boundary An area where a column of hot material rises from deep within a planet’s mantle and heats the lithosphere above it, often causing volcanic activity at the surface. transform boundary rift valley magnetic reversal hot spot KEY CONCEPT SUMMARY

Plates converge or scrape past each other. 1.4 Plates converge or scrape past each other. Crust is destroyed or folded at convergent boundaries. • Subduction boundaries form island arcs, deep-ocean trenches, and coastal mountains. subduction continental-continental collision • Collision boundaries can form mountains. oceanic-oceanic subduction oceanic-continental subduction SECTION OUTLINE

Plates converge or scrape past each other. 1.4 Plates converge or scrape past each other. Crust is destroyed or folded at convergent boundaries. • Subduction boundaries form island arcs, deep-ocean trenches, and coastal mountains. subduction continental-continental collision • Collision boundaries can form mountains. Crust is neither formed nor destroyed at transform boundaries. oceanic-oceanic subduction oceanic-continental subduction SECTION OUTLINE

1.4 subduction Plates converge or scrape past each other. continental-continental collision The process by which an oceanic tectonic plate sinks under another plate into Earth’s mantle. oceanic-oceanic subduction oceanic-continental subduction KEY CONCEPT SUMMARY

continental-continental collision 1.4 Plates converge or scrape past each other. subduction continental-continental collision continental-continental collision A boundary along which two plates carrying continental crust push together. oceanic-oceanic subduction oceanic-continental subduction KEY CONCEPT SUMMARY

oceanic-oceanic subduction 1.4 Plates converge or scrape past each other. subduction oceanic-oceanic subduction continental-continental collision A boundary along which a plate carrying oceanic crust sinks beneath another plate with oceanic crust. oceanic-oceanic subduction oceanic-continental subduction KEY CONCEPT SUMMARY

oceanic-continental subduction 1.4 Plates converge or scrape past each other. subduction oceanic-continental subduction continental-continental collision A boundary along which a plate carrying oceanic crust sinks beneath a plate with continental crust. oceanic-oceanic subduction oceanic-continental subduction KEY CONCEPT SUMMARY

1.1 Earth has several layers. I. Earth has several layers. inner core A. Earth is made up of materials with different densities. outer core mantle B. Earth’s layers have different properties. crust 1. Core, Mantle, Crust lithosphere C. The lithosphere is made up of many plates. asthenosphere tectonic plate KEY CONCEPT SUMMARY

Continents change position over time. 1.2 Continents change position over time. II. Continents change position over time. continental drift A. Continents join together and split apart. Pangaea 1. Evidence for Continental Drift mid-ocean ridge 2. Pangaea and Continental Drift convection B. The theory of plate tectonics explains how plates and their continents move. convection current theory of plate tectonics 1. Evidence from the Sea Floor 2. Causes of Plate Movement 3. Putting the Theory Together KEY CONCEPT SUMMARY

1.3 Plates move apart. III. Plates move apart. divergent boundary A. Tectonic plates have different boundaries. B. The sea floor spreads apart at divergent boundaries. convergent boundary transform boundary 1. Mid-Ocean Ridges and Rift Valleys 2. Sea-Floor Rock and Magnetic Reversals rift valley C. Continents split apart at divergent boundaries. magnetic reversal D. Hot spots can be used to track plate movements. hot spot KEY CONCEPT SUMMARY

Plates converge or scrape past each other. 1.4 Plates converge or scrape past each other. IV. Plates converge or scrape past each other. subduction A. Tectonic plates push together at convergent boundaries. continental-continental collision 1. Continental-Continental Collision 2. Oceanic-Oceanic Subduction oceanic-oceanic subduction 3. Oceanic-Continental Subduction oceanic-continental subduction B. Tectonic plates scrape past each other at transform boundaries. C. The theory of plate tectonics helps geologists today. KEY CONCEPT SUMMARY