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.