Section #: 20.1
Crust-Mantle Relationships
Practice Test
1.
What is isostasy?
a.
Continental crust floats on top of oceanic crust.
b.
mantle material upwelling around crustal material because of gravity
c.
equilibrium that has been established between continental and oceanic crust
d.
Continental and oceanic crust displace the mantle, so they are in equilibrium.
Hint
2.
Why do mountains have roots?
a.
If erosion removes mass from the mountains, the roots will keep the continental crust at the same elevation.
b.
The roots provide buoyancy to support the large mass of the mountains.
c.
Mountains are less dense than their roots.
d.
The roots of mountains keep the mountains in one geographic location.
Hint
3.
Using the map, infer where the highest elevations are in the U.S.
a.
in the center of the country
b.
in the south, along the Florida coast
c.
in the western states
d.
in the northeastern states
Hint
4.
The roots of a mountain are __________.
a.
often many times deeper than the mountain is high
b.
always as deep as the mountain is high
c.
always the same depth as the mountain is high
d.
often shallower than the mountain is high
Hint
5.
What are two main elevation modes on Earth?
a.
0 km to 1 km above sea level and 4 km to 5 km below sea level
b.
1 km to 4 km above sea level
c.
4 km to 5 km above sea level and 0 km to 1 km below sea level
d.
4 km to 5 km above sea level
Hint
6.
What is isostatic rebound?
a.
the process of mountains eroding to flat ground
b.
when oceanic crust rises above continental crust
c.
how the mantle keeps mountains upright
d.
when the crust rises as it loses overlying material and mass
Hint
7.
Continental crust is made mostly of __________ and oceanic crust is made mostly of __________.
a.
granite, basalt
b.
basalt, granite
c.
granite, rhyolite
d.
grabbo, basalt
Hint
8.
Why does continental crust rise higher above the surface of Earth than oceanic crust?
a.
Continental crust is less dense than the mantle.
b.
Continental crust is thinner and less dense.
c.
Oceanic crust is under continental crust.
d.
Continental crust is thicker and is less dense.
Hint
