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Characteristics of the Seafloor Answers

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1
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Which is the first step in the seafloor spreading process?

A
A crack forms in oceanic crust.
B
Volcanoes erupt under the ocean.
C
Molten rock rises up through the crust.
D
Dense plates are subducted under less dense plates.
2
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Which information did the Glomar Challenger study in 1968?

A
the rate of seafloor spreading
B
the direction of seafloor spreading
C
the age of rocks in various places in the ocean
D
the contents of rocks in various places in the ocean
3

Which statement describes the relationship between seafloor spreading and continental drift?

A
As the seafloor spreading occurs, the continents do not move.
B
As the continents move, they pull the seafloor with them.
C
As the continents move, they create new seafloor at the coast.
D
As the seafloor spreading occurs, the continents move.
4

Which evidence originally supported Hess’s idea of seafloor spreading in 1968?

A
Younger rocks are closer to mid-ocean ridges.
B
The destruction of crust occurs at deep-sea trenches.
C
Oceanic rocks are pillow-shaped when formed.
D
Rocks across the ocean floor have alternating magnetic stripes.
5

Which statement accurately describes one aspect of plate tectonics that involves subduction and seafloor spreading?

A
Older crust is melted at subduction zones.
B
Crust is created at the coastlines of continents.
C
Continents do not move as a result of seafloor spreading and subduction.
D
Crust is created as the mantle hardens under the lithosphere.
6

Which statement describes the cyclic nature of seafloor spreading?

A
Continents are created.
B
New oceanic crust is created.
C
Volcanoes erupt and remove crust.
D
Old crust gets thicker at subduction zones.
7

Which concept is described in the theory proposed by Hess?

A
Continents do not move.
B
Cool rock pushes through the crust.
C
Trenches are sites of seafloor spreading.
D
Mid-ocean ridges are sites of seafloor spreading.
8

At the end of seafloor spreading, where does the molten rock solidify?

A
center of the ridge
B
on the edge of the ridge
C
under the new rock
D
between the old rock layers
9

Which material rises from cracks in oceanic crust?

A
dense crust
B
molten rock
C
continental crust
D
pillow-shaped rocks
10

According to the theory proposed by Harry Hess, what causes continents to move?

A
continental drift
B
magnetic polarity
C
seafloor spreading
D
deep-ocean trenches
11

How do magnetic stripes of iron in ocean rock provide evidence of seafloor spreading?

A
They show when Earth's poles reversed.
B
They show how the density of the seafloor has changed.
C
They reveal a matching pattern on either side of the ridge.
D
They reveal differences in the mineral composition of newly created rock.
12

How does oceanic crust move along mid-ocean ridges?

A
away from dense crust
B
parallel to the ridge
C
away from the ridge
D
under less dense crust
13

Which is the first step in the seafloor spreading process?

A
A crack forms in oceanic crust.
B
Volcanoes erupt under the ocean.
C
Molten rock rises up through the crust.
D
Dense plates are subducted under less dense plates.
14

Which statement accurately describes one aspect of plate tectonics that involves subduction and seafloor spreading?

A
Older crust is melted at subduction zones.
B
Crust is created at the coastlines of continents.
C
Continents do not move as a result of seafloor spreading and subduction.
D
Crust is created as the mantle hardens under the lithosphere.
15

Which statement describes the cyclic nature of seafloor spreading?

A
Continents are created.
B
New oceanic crust is created.
C
Volcanoes erupt and remove crust.
D
Old crust gets thicker at subduction zones.
16

Which concept is described in the theory proposed by Hess?

A
Continents do not move.
B
Cool rock pushes through the crust.
C
Trenches are sites of seafloor spreading.
D
Mid-ocean ridges are sites of seafloor spreading.
17

According to the theory proposed by Harry Hess, what causes continents to move?

A
continental drift
B
magnetic polarity
C
seafloor spreading
D
deep-ocean trenches
18

Which evidence originally supported Hess’s idea of seafloor spreading in 1968?

A
Younger rocks are closer to mid-ocean ridges.
B
The destruction of crust occurs at deep-sea trenches.
C
Oceanic rocks are pillow-shaped when formed.
D
Rocks across the ocean floor have alternating magnetic stripes.
19

At the end of seafloor spreading, where does the molten rock solidify?

A
center of the ridge
B
on the edge of the ridge
C
under the new rock
D
between the old rock layers
20

Which information did the Glomar Challenger study in 1968?

A
the rate of seafloor spreading
B
the direction of seafloor spreading
C
the age of rocks in various places in the ocean
D
the contents of rocks in various places in the ocean

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