Volcanic Activity
Practice Test
1.
When magma reaches Earth's surface it is called __________.
a.
rock
b.
lava
c.
a batholith
d.
intrusive
2.
What branch of Bowen's reaction series cools with a continuous change in composition?
a.
the carbonates
b.
the feldspars
c.
the silica chains
d.
the iron-magnesium groups
3.
Identify the subduction zone in the figure.
a.
A
b.
D
c.
B
d.
C
4.
Where do most volcanoes form?
a.
at plate boundaries
b.
far from plate boundaries
c.
in the southern hemisphere
d.
along the Mid-Atlantic Ridge
5.
Which rock shown in the figure cooled the fastest?
a.
glassy
b.
fine-grained
c.
porphorytic
d.
coarse-grained
6.
What is thought to be the driving mechanism of plate movement?
a.
volcanoes
b.
conduction of heat in the mantle
c.
convection currents in the mantle
d.
continental drifting
7.
What letter in the figure depicts the possible beginning of plutons like dikes and sills?
a.
A
b.
none of the above
c.
C
d.
B
8.
How are fjords formed?
a.
sea level rise
b.
longshore current
c.
tectonic forces
d.
global cooling
9.
Why did Wegener think that the Antarctic continent had been closer to the equator in the geologic past?
a.
evidence of fossil fish
b.
existence of volcanic rocks
c.
existence of coal beds
d.
existence of the Transantarctic Mountains
10.
Which letter in the figure demonstrates magma melting rocks after they are broken off and sink?
a.
A
b.
C
c.
none of the above
d.
B
11.
How are the convection currents set in motion?
a.
slab push and ridge pull
b.
slab push
c.
the heat from radioactive decay
d.
spreading mid-ocean ridges
12.
Why does magma move up to and through Earth's crust?
a.
It is cooler than the crust.
b.
It is less dense than surrounding rock.
c.
It is more dense than surrounding rock.
d.
It is more viscous than ocean water.
13.
An expedition brings up a piece of rock from the Gauss normal epoch. According to the figure, what is the probability that it came from a time when the magnetic field is the same as today?
a.
unlikely
b.
very likely
c.
likely
d.
highly unlikely
14.
What is the source of heat inside Earth that melts rocks into magma?
a.
geothermal energy
b.
the decay of radioactive elements
c.
other molten rocks
d.
Earth's core is hotter for no reason.
15.
The map shows where the continents are likely to move in the next 50 million years. The shaded area represents their present position. According to the data on this map, what kind of boundary is found between the Americas and Africa?
a.
convergent
b.
divergent
c.
subduction
d.
transform
16.
The table shows how many eruptions were experienced by volcanoes in the past 100,000 years. Which volcano is the least likely to experience a huge eruption in present day?
Feature
State
Late Pleistocene
Holocene
Huge
Huge
Large
Medium
Small
Mount Baker
WA
1
3
Glacier Peak
WA
2
7
Mount Rainier
WA
1
1
10
Mount St. Helens
WA
7
Mount Adams
WA
4
Mount Hood
OR
3
Mount Jefferson
OR
1
Three Sisters
OR
2
2
Newberry Caldera
OR
1
3
Crater Lake
OR
1
2
Medicine Lake
CA
8
8
Mount Shasta
CA
1
2
10
Lassen Peak
CA
4
1
2
Total
7
1
10
20
49
a.
Mount Rainier
b.
Mount Hood
c.
Lassen Peak
d.
Mount Shasta
17.
The supercontinent from Wegener's theory of continental drift is called __________.
a.
Gondwanaland
b.
Pangaea
c.
Laurasia
d.
North America
18.
What breaks mid-ocean ridges into smaller sections?
a.
shelf breaks
b.
fracture zones
c.
abyssal plains
d.
submarine canyons
19.
What is an example of an igneous ore deposit?
a.
hydrothermal deposits
b.
placer deposits
c.
metal-rich quartz veins
d.
porphyritic deposits
20.
According to the data shown in the figure, what was Earth's magnetic polarity like 5 million years ago?
a.
the reverse of today
b.
pointing in an east-west direction
c.
there was no magnetic field
d.
the same as today
