Volcanic Activity
Practice Test
1.
When does magma form?
SC.D.1.4.2
a.
when volcanoes erupt
b.
when grains have been compacted together
c.
when temperatures are hot enough to melt rock
d.
when new minerals form due to chemical changes in the rock
2.
What letter in the figure depicts the possible beginning of plutons like dikes and sills?
SC.D.1.4.2
a.
A
b.
C
c.
none of the above
d.
B
3.
What type of igneous pluton is tabular and parallel to surrounding rock layers?
SC.D.1.4.2
a.
a sill
b.
a batholith
c.
a stock
d.
a dike
4.
A __________ is a large intrusive igneous rock body that covers at least 100 square km.
SC.D.1.4.2
a.
laccolith
b.
batholith
c.
dike
d.
sill
5.
What type of volcano forms from alternating layers of tephra and nonexplosive lava?
SC.D.1.4.2
a.
caldera
b.
shield volcano
c.
cinder cone
d.
composite volcano
6.
What type of texture do most plutons have?
SC.D.1.4.2
a.
intermediate grained
b.
fine grained
c.
pegmatitic
d.
coarse grained
7.
Why does magma move up to and through Earth's crust?
SC.D.1.4.2
a.
It is more viscous than ocean water.
b.
It is more dense than surrounding rock.
c.
It is less dense than surrounding rock.
d.
It is cooler than the crust.
8.
Where do most volcanoes form?
SC.D.1.4.2
a.
in the southern hemisphere
b.
along the Mid-Atlantic Ridge
c.
at plate boundaries
d.
far from plate boundaries
9.
What is the name for an igneous intrusion that is smaller than a batholith but similar in shape?
SC.D.1.4.2
a.
sill
b.
stock
c.
laccolith
d.
dike
10.
Rock fragments thrown into the air during a volcanic eruption are called __________.
SC.D.1.4.2
a.
granite
b.
extrusive
c.
tephra
d.
lava
11.
When magma reaches Earth's surface it is called __________.
SC.D.1.4.2
a.
lava
b.
intrusive
c.
a batholith
d.
rock
12.
Rhyolitic magma has the __________ viscosity, the __________ gas content and the __________ silica content of any type of magma.
SC.D.1.4.2
a.
lowest, highest, highest
b.
lowest, lowest, lowest
c.
highest, highest, highest
d.
highest, lowest, lowest
13.
What type of magma has the lowest silica content and is the least explosive?
SC.D.1.4.2
a.
andesitic magma
b.
granitic magma
c.
rhyolitic magma
d.
basaltic magma
14.
How is a volcanic crater connected to a magma chamber?
SC.D.1.4.2
a.
by a vent
b.
by tephra
c.
by a hot spot
d.
by a sill
15.
What is the name of a large volcanic crater over 1 km in diameter?
SC.D.1.4.2
a.
a vent
b.
a stock
c.
a batholith
d.
a caldera
