Plate Tectonics
Boundaries
Volcanoes
Lava and Magma
Earthquakes
100
The shapes of which two continents' coastlines led to early suggestions they had been joined at one time?
South America and Africa
100
What is a rift valley and what does it mark?
Marks a boundary between two plates.
100
What are the three types of earthquakes called?
Shield, Cindercone, and Composite
100
Where does magma exist?
Below the earth's surface
100
What is an epicenter?
The location where the earquake hits.
200
The theory of plate tectonics helps explain the locations of
Earthquakes and volcanoes
200
What are two types of convergent boundaries?
Collision boundaries and subduction boundaries
200
At a subduction boundary, where is a volcano most likely to form?
On the overriding plate
200
What are the two types of magma and how are they different?
Andesitic magma is associated with relatively explosive eruptions, but basaltic magma is associated with relatively nonexplosive eruptions.
200
what is the cause of most major earthquakes?
Strain that builds up along faults at or near plate boundaries.
300
Minerals in igneous rocks can show the direction of Earth's what?
Lack of geologic activity
300
When does a chain of volcanoes commonly form?
When an oceanic plate subducts
300
Name two things which Pyroclastic materials include?
Ash and _________
300
Does magma rise to the surface because it is more or less dense than surrounding materials?
Less dense
300
Do the deepest earthquakes tend to occur at divergent boundaries, transform boundaries, or subduction boundaries?
Subduction boundaries
400
Describe a lithosperic plate.
Rigid and move about on the asthenosphere
400
When two oceanic plates converge, which one is the one that subducts?
The one that is denser
400
Which are the most explosive volcanoes?
Composite
400
What kind of of lava flow forms underwater?
pillow lava
400
What forms over a hot spot?
Volcanic islands
500
Why didn't Wegner's fellow scientists believe in his theory?
He could not explain why the continents moved.
500
When would the continents eventually become welded together?
If two plates carrying continental crust share a convergent boundary.
500
Why do Scientists monitor volcanoes?
So that they might be able to predict volcanic eruptions.
500
What set of conditions affects the formation of magma?
Temperature, Pressure, and Water Content
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