Plate Tectonics – Unit 8 – Study Guide - KEY Unit Overview - Surface and subsurface processes that are involved in the formation and destruction of earth materials are identified in this unit. Standards: Students will investigate the scientific view of how the earth’s surface is formed. Compare and contrast the Earth’s crust, mantle, and core including temperature, density, and composition. Recognize that lithospheric plates constantly move and cause major geological events on the earth’s surface. Explain the effects of physical processes (plate tectonics, erosion, deposition, volcanic eruption, gravity) on geological features including oceans (composition, currents, and tides). Questions – Students will be asked to answer these question throughout the unit and on the unit test. #1 How are the earth’s layers alike and different? #2 What challenges stand in the way of sending explorers to the center of the earth? #3 How does the movement of lithospheric plates cause major events on earth’s surface? #4 What evidence do scientists have that continents were once joined together? #5 Why do mountains often occur in ranges thousands of kilometers long? #6 What can fossils tell us about movements of the plates in the past? Continental Drift/Plate Movement 1. Alfred Wegener was a German scientist that proposed The Continental Drift Theory in 1912. 2. The theory that Earth’s continents slowly move is called The Continental Drift Theory. 3. Pangaea was the most recent of a succession of supercontinents that have formed and broken up over time. Scientists believe this supercontinent occurred 200 million years ago. 4. If a fossil is found multiple places in the world, what have scientists hypothesize might have happened a long time ago? They were once on a single continent that has separated 5. Evidence of Continental Drift 1 - Fossils – ancient reptile found in South America and Eastern Africa 2 - Geology - The continents seem to fit together like a puzzle & same type of rock found in South America and in Africa 3 - Climate – Greenland now lies in the Arctic Circle and is covered in ice but has fossils of tropical plants. 6. The Theory of Plate Tectonics is the theory that states that Earth’s lithosphere is made up of huge plates that move over the surface of Earth. 7. Lithospheric plates constantly move. 8. At the edges or boundaries of the plates, Earth's crust is in motion. 9. Moving plates cause major changes in a world map over tens of millions of years. 10. Plate movement causes major geologic events such as volcanoes, earthquakes, and mountain formation. 11. Why do you scientists think ocean fossils are sometimes found on the tops of mountains? Seafloor has been raised by tectonic plate movement 12. North American plate consists of both continental and oceanic crust. 13. The theory of plate tectonics connects the evidence for the formation, movement, and destruction of the plates. 14. Some changes in the earth’s surface are abrupt such as earthquakes and volcanic eruptions while other changes happen very slowly such as uplift and wearing down of mountains. 15. Major geological events, such as earthquakes, volcanic eruptions, and mountain building, result from tectonic plate movement. Convection Currents 16. Going from the surface to the center of the earth, list the layers in order. Lithosphere (crust), Asthenosphere (mantle), outer core, inner core 17. The earth is layered with a lithosphere that contains the crust and uppermost mantle. 18. The crust is the upper part of the rigid lithosphere and has a different composition under land than it does on the ocean floor. 19. The lithosphere is divided into separate plates which move very slowly in response to the convection currents in the mantle. 20. The mantle is solid but capable of flow (like hot asphalt or fudge). 21. Below the rigid lithosphere, the mantle consists of hot rock of tar-like consistency, which slowly moves or flows. This is also called the asthenosphere. 22. Convection is the energy transfer by the movement of material. 23. Convection currents are caused by as heated molten rock in the mantle become less dense and rise. At the same time other molten rock cools and become more dense so they sink. 24. Convection currents are the continuous loop of sinking and rising hot, soft rocks caused by energy transfer in the asthenosphere (mantle) of Earth 25. Heat from the mantle and core creates convection currents. 26. Convections currents in the mantle cause the tectonic plates to move. 27. Where do convection currents take place? The mantle 28. Less dense things rise while more dense things sink. Divergent Boundaries 29. Draw pictures of the three types of boundaries: Divergent Convergent Transform/Strike-slip Picture showing plates moving apart. Picture showing plates Picture showing plates moving toward each other. sliding past each other. 30. Crust is destroyed at convergent boundaries. Crust is formed at divergent boundaries. Crust is neither destroyed or formed at transform boundaries. 31. Divergent boundaries move apart creating new crust. 32. Mid-ocean ridges form at divergent boundaries by pushing up seafloor. 33. Mid-ocean ridges are underwater mountain ranges that can form at a divergent boundary. 34. A rift valley is a gap at divergent boundaries where molten material rises to build new crust. 35. Rift valleys can occur in the ocean to create mid-ocean ridges or on continents to form volcanoes, lakes, or rivers. Convergent & Transform Boundaries 36. The two types of crust are oceanic and continental. Oceanic crust is more dense than continental crust. 37. Convergent boundaries push together. 38. Subduction is the sideways and downward movement of the edge of a plate of the earth's crust into the mantle beneath another plate. The more dense plate will go under the less dense plate. 39. The three types of convergent boundaries are Continental-Continental Oceanic-Oceanic Oceanic-Continental 40. When continental crust meets continental crust at a convergent boundary, a collision occurs, resulting in folds, faults, and high mountains. 41. Ocean trench is a long narrow trench that forms when one plate goes under another at a convergent boundary. This can be oceanic-oceanic OR oceanic-continental. 42. At convergent boundaries oceanic plates will go under continental plates because oceanic crust is more dense than continental crust. 43. Oceanic-continental convergent boundaries can form mountains. 44. At convergent plate boundaries known as subduction zones, a trench and deep earthquakes mark the zone where a slab of oceanic lithosphere descends into the mantle, and volcanoes and mountain ranges form on adjacent land. 45. Oceanic crust is younger at an ocean ridge (divergent boundary) and older near a trench (convergent boundary). 46. Transform plates slide past one another. 47. Transform boundaries connect other plate boundaries and are characterized by earthquakes. 48. The San Andreas Fault in California is a transform boundary. This is a very active boundary causes earthquakes . 49. Earthquakes represent sudden breaks in crust continuously stressed by plate movement. Gradually over time, the same movements result in major crustal features. Volcanoes/Mountains 50. Only under special conditions (at hot spots and along plate boundaries) does the crust melt to make magma, which may then rise to the surface to make a volcanic eruption. 51. The three places volcanoes form are Subduction zones at convergent boundaries Divergent boundaries Hot spots 52. List the 4 types of volcanoes. Stratovolcano, Cinder Cone , Caldera, & Shield. 53. A hot spot is where heat from a plume (heated rising rocks in asthenosphere) melts some of the rock in the tectonic plate above. 54. Hot spots can form volcanoes. 55. What state was formed from a hot spot? Hawaii 56. List the two types of mountains. Folded Mountains, Fault-Block Mountains 57. Draw and describe Folded Mountains. Rock under extreme pressure for long periods of time will fold like clay. Folding bends many layers of rocks without breaking them. 58. Draw and describe Fault Block Mountains. Mountains with sharp, jagged peaks are produced when rock layers break apart at convergent boundaries and are tilted upward. Vocabulary magma – hot fluid or semi fluid material below or within the earth's crust fossil - a remnant or trace of an organism from the past, such as a skeleton or leaf imprint, embedded and preserved in the earth's crust subduction – the sideways and downward movement of the edge of a plate of the earth's crust into the mantle beneath another plate Continental Drift Theory - a theory explaining the gradual movement of the continents across the earth's surface through geological time Alfred Wegener - a German scientist that proposed continental drift in 1912 mid-ocean ridge – underwater mountain ranges that can form at a divergent boundary ocean trench - a long narrow trench when one plate goes under another at a convergent boundary rift valley – a gap at divergent boundaries where molten material rises to build new crust. This can be at oceanic (mid-ocean ridges) and continental (volcanoes, lakes, rivers) hot spot – heat from a plume (heated rising rocks in asthenosphere) melts some of the rock in the tectonic plate above – can cause volcanoes to form volcano – an opening in Earth’s crust through which molten rock, rock fragments, and hot gasses erupt plate boundaries – where the edges of two or more tectonic plates meet convection – energy transfer by the movement of material – caused by differences in density convection currents –continuous loop of sinking and rising of hot, soft rocks caused by energy transfer in the asthenosphere (mantle) of Earth fault - a crack in the earth's crust Theory of Plate Tectonics – theory that stats that Earth’s lithosphere is made up of huge plates that move over the surface of Earth.