Section #: 17.2
Seafloor Spreading
Practice Test
1.
A __________ is a device that can detect changes in the strength of the magnetic field.
SC.D.1.4.2
a.
GPS
b.
sonar
c.
satellite
d.
magnetometer
Hint
2.
What is the study of Earth's magnetic record?
SC.D.1.4.3
a.
paleogeography
b.
paleomagnetism
c.
magnetometer
d.
paleontology
Hint
3.
What is the polarity of a magnetic field that has the same polarity as the present magnetic field?
SC.D.1.4.3
a.
a magnetic reversal
b.
an isochron
c.
a normal polarity
d.
a reverse polarity
Hint
4.
The thickness of ocean sediments that are close to a mid-ocean ridge is __________ the thickness of ocean sediments that are far from mid-ocean ridges.
SC.D.1.4.2
a.
always 100 times
b.
the same as
c.
less than
d.
more than
Hint
5.
What two topographic features of the ocean floor were discovered only with the use of sonar?
SC.D.1.4.2
a.
mid-ocean ridges and earthquakes
b.
shallow-sea trenches and volcanic islands
c.
volcanic islands and mid-ocean ridges
d.
mid-ocean ridges and deep-sea trenches
Hint
6.
What causes the seafloor to spread?
SC.D.1.4.2
a.
earthquakes
b.
sinking magma
c.
rising molten magma
d.
drifting continental crust
Hint
7.
Rocks close to mid-ocean ridges are __________ rocks far from mid-ocean ridges.
SC.D.1.4.2
a.
the same age as
b.
younger than
c.
older than
d.
a different composition than
Hint
8.
What is an isochron?
SC.D.1.4.2
a.
a line on a seafloor map that connects points of equal age
b.
a part of a mid-ocean ridge
c.
a line on a seafloor map that connects points of equal elevation
d.
a point on a seafloor map that has a magnetic reversal
Hint
9.
Harry Hess' theory of __________ explained how ocean crust is generated and destroyed.
SC.D.1.4.2
a.
continental movement
b.
seafloor spreading
c.
continental drift
d.
plate tectonics
Hint
