Name: _________________________
Date: ________________________
Plate Tectonics Test Review Sheet (Ch.1)
Vocabulary: Define and make sure you know the following –
Geologist – scientist who studies the Earth
Constructive forces – creates land, builds up the land (Ex: volcanic eruption)
Destructive forces – breaks down the land (Ex: weathering)
Seismic Wave – Earthquake wave
Pangaea – Supercontinent formed when ALL the continents were joined
together
6. Mid-ocean ridge – place in the middle of an ocean where lava comes up,
pushes old oceanic crust apart and forms new ocean floor
7. Deep-ocean trench – place where old oceanic crust is sucked back into the
mantle
8. Subduction – process by which old oceanic crust sinks back into the mantle
9. Rift valley – place where magma comes out, forms new crust, and pushes old
crust aside
10. Continental Drift – Theory that all the continents were joined together, then
broke apart and spread out (theory by Alfred Wegener)
11. Radiation – Heat transfer through empty space (ex: how the Sun heats the
Earth)
12. Convection – Heat transfer through movement of a fluid (ex: boiling water)
13. Conduction – Heat transfer by direct contact (ex: touching a hot pot)
14. Asthenosphere – layer of melted rock just under the crust (lithosphere)
15. Lithosphere – all Earth’s land; layer of solid rock that includes all of the crust
and the very top of the mantle
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Key Ideas and Skills:
1. Earth’s Layers
a) Be able to interpret a diagram showing earth’s layers: crust, mantle, outer
core, inner core, asthenosphere, and lithosphere.
b) Be able to describe the characteristics of each layer (composition and phase).
1) crust – outermost layer of the Earth, made of solid rock
a) continental crust – crust under the continents, made of granite (less dense)
b) oceanic crust – crust under the oceans, made of basalt (Dense)
c) Why do they have different densities? Different composition
2) mantle – layer of molten rock under the crust
3) outer core – layer of liquid metal (nickel and iron)
4) inner core – layer of solid metal (nickel and iron)
5) asthenosphere – layer of melted rock under the lithosphere; contains
convection currents which move the molten rock and push around the plates
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Name: _________________________
Date: ________________________
6) lithosphere – all of the crust and the top of the mantle (solid rock)
II. Heat Transfer
a) radiation – Heat transfer through empty space (ex: warming your hands over
a fire)
b) conduction – Heat transfer by direct contact (ex: touching a hot stove)
c) convection – Heat transfer by movement of a fluid (liquid or gas)
III. Alfred Wegner and the Theory of Continental Drift
a) What was his theory called?
Continental Drift
b) What did his theory say? And what is the name of the super-continent?
All continents were joined together to for a supercontinent (that broke
apart) called Pangea
c) What evidences did Wegner give to support his theory?
1. Coastlines – the continents fit together like a puzzle
2. Mountains – line up on different continents
3. Coal – found in Antarctica, but coal only forms from the remains of tropical
forests, so this suggests Antarctica was near the equator in the past
4. Fossils – the same type of fossils were found on different continents
5. Glaciers – left scratches called striations that line up on different continents
d) Why wasn’t Wegner’s theory accepted initially?
He could not explain how the continents moved. He didn’t know the force
that could move continents.
e) What new evidence caused scientists to accept Wegner’s theory?
The discovery that Sea Floor spreading moves the continents and those
convection currents in the asthenosphere move plates and the plates moves
the continents
IV. Sea-floor Spreading
a) What is sea-floor spreading? And where does it occur at?
Magma comes up at a mid-ocean ridge or rift valley and pushes the old
crust aside.
b) What evidence supports sea-floor spreading?
1. The temperature of rocks is hottest by ridges and coldest by trenches
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Name: _________________________
Date: ________________________
2. Age of ocean rocks – youngest rocks are near the ridges, oldest rocks
are near the trenches
<REMEMBER: Hot young rocks at the ridge, cold old rocks at the trench!>
3. Pillow-shaped rocks – Scientists have found pillow-shaped rocks which
formed when lava cooled quickly in cold water
c) Why does ocean floor subduct into the mantle underneath continental crust?
Oceanic crust is denser than continental crust
d) What is subduction?
Sinking of oceanic crust; process by which old oceanic crust sinks down a
deep-ocean trench and back into the mantle
V. Types of plate boundaries (Be able to identify them based on diagrams and
describe what happens at each boundary type)
a) Transform boundary – two plates slip past each other in side by side
*San Andreas Fault in California is an example.
b) Divergent boundary – plates move apart (diverge), makes a rift valley or midocean ridge; sea floor spreading occurs here  
c) Convergent boundary – plates come together (converge)  
1. oceanic-oceanic – the denser oceanic plate will subduct at a trench
2. oceanic-continental – the denser oceanic crust sinks under continental
crust because oceanic crust is denser; this happens at a trench
3. continental-continental – two plates fold up forming mountains
(ex: Himalayas formed this way and are still growing every year!)
VI. Plate Tectonics
a) What does the Theory of Plate Tectonics say?
Earth’s crust is broken into lithospheric plates that float on the
asthenosphere
b) What are convection currents?
The flow that transfer heat in a fluid
Warmer, less dense material rises
Cooler, denser material sinks
c) What causes convection currents?
Heat causes fluid to become less dense and rise, then as the fluid cools, it
sinks again
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Name: _________________________
Date: ________________________
d) What eventually happens to convection currents when the heat source is
removed?
The convection current will slow down and then eventually stop
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