True/False
Indicate whether the statement is true or false.
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1.
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During a volcanic eruption, melted rock leaves the magma chamber and moves up the conduit.
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2.
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When magma leaves the vent of a volcano it is called basalt magma.
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3.
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Extinct volcanoes are volcanoes that are not active now, but may become active again in the future.
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4.
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The two ways to make rocks melt are: lower pressure and added water.
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5.
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A dike is formed when magma leaves the conduit of a volcano by moving sideways along weaknesses between rock layers.
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6.
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Basalt magma is runny because of its low silica content.
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7.
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Pumice is the type of rock the continental plates are made of.
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8.
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Rocks formed when magma cools on or below the surface are called igneous rocks.
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9.
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When magma cools fast on the surface of Earth, it produces large crystals in the igneous rock that it forms.
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10.
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The volcanoes of the Hawaiian Islands are composite volcanoes due to rich silica-bearing magma.
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11.
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Pyroclastic flow are mudflows that may accompany a stratovolcano if water is present in the ground.
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Multiple Choice
Identify the choice that best completes the statement or answers the question.
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12.
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Melted rock located within Earth’s crust is known as:
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a.
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lava. |
b.
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magma. |
c.
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sill. |
d.
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conduit. |
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13.
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Magma is “stored” within a volcano inside the:
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a.
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vent. |
b.
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sill. |
c.
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dike. |
d.
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magma chamber. |
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14.
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Once magma leaves the vent of a volcano it is known as:
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a.
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lava. |
b.
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sill. |
c.
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dike. |
d.
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molds. |
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15.
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When magma drains part way down the conduit the vent looks like a large bowl, called a:
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a.
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resurgent dome. |
b.
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lava lake. |
c.
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sill. |
d.
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caldera. |
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16.
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A ____ may form on the caldera floor if magma begins to return up the conduit.
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a.
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sill |
b.
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resurgent dome |
c.
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lava lake |
d.
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dike |
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17.
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____ volcanoes are erupting or have erupted recently, and are expected to erupt again in the near future.
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a.
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Active |
b.
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Dormant |
c.
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Extinct |
d.
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Current |
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18.
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____ volcanoes are not active now, but may become active again in the future.
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a.
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Extinct |
b.
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Dormant |
c.
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Sleeping |
d.
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Hibernating |
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19.
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____ volcanoes are at the end of their life and are no longer able to erupt.
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a.
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Active |
b.
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Dormant |
c.
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Extinct |
d.
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Dead |
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20.
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Rock under ____ pressure melts at a higher temperature.
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a.
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low |
b.
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high |
c.
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balanced |
d.
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zero |
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21.
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Rock that contains ____ melts at a lower temperature.
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a.
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salt |
b.
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calcium |
c.
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water |
d.
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gas |
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22.
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Magma may move upward in a sheet, which is called a:
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a.
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sill. |
b.
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conduit. |
c.
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dike. |
d.
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vent. |
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23.
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Magma may leave a volcano gently or with violent force from the opening known as the:
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a.
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conduit. |
b.
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vent. |
c.
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dike. |
d.
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sill. |
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24.
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Ship Rock in New Mexico and Devil’s Tower National Monument are examples of:
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a.
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active volcanoes. |
b.
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dormant volcanoes. |
c.
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volcanic necks. |
d.
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lava lakes. |
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25.
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Magma formed from melted material from the lower mantle is called:
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a.
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basalt magma. |
b.
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pillow lava. |
c.
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silica. |
d.
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sill. |
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26.
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When basalt magma repeatedly oozes out at a mid-ocean ridge and hits the cold seawater it forms a distinctive lava known as:
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a.
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basalt lava. |
b.
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pillow lava. |
c.
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sea lava. |
d.
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silica. |
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27.
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____ are types of volcanoes that are not formed at a tectonic plate boundary.
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a.
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Volcanic islands |
b.
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Calderas |
c.
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Cinder Cones |
d.
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Plumes |
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28.
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Volcanic island chains are formed as lithospheric plates move over the top of plumes that are known as:
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a.
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hot spots. |
b.
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dikes. |
c.
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vents. |
d.
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calderas. |
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29.
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The Hawaiian Islands are an example of a(n):
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a.
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mid-ocean ridge. |
b.
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volcanic island chain. |
c.
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explosive volcano chain. |
d.
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cinder cone volcano. |
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30.
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Volcanoes near subduction zones tend to form magma that is high in:
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a.
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lava. |
b.
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silica. |
c.
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basalt. |
d.
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density. |
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31.
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A(n) ____ is a string of volcanic islands that will form along the lip of the upper plate if the subduction zone is in open water.
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a.
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island arc |
b.
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caldera |
c.
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cinder cone |
d.
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volcanic ridge |
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32.
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Volcanic islands are formed when ____ bring up material from deep within the lower mantle to the surface.
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a.
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dikes |
b.
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sills |
c.
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calderas |
d.
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plumes |
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33.
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A ____ is a type of quiet volcano where magma produces a low mound on Earth’s surface.
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a.
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cinder cone |
b.
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shield volcano |
c.
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stratovolcano |
d.
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coastal volcano |
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34.
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When lava formed from thick magma piles up around a vent, it forms a tall volcano called a(n):
|
a.
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cinder cone. |
b.
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stratovolcano. |
c.
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shield volcano. |
d.
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island arc volcano. |
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35.
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Pyroclastic flow is lava and exploding material that typically comes from what type of volcano?
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a.
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Stratovolcanoes |
b.
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Shield Volcanoes |
c.
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Cinder Cones |
d.
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Plumes |
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36.
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Low amounts of silica make magma that is:
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a.
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thick. |
b.
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sticky. |
c.
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dense. |
d.
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runny. |
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37.
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A black, glassy igneous rock that cools quickly, preventing crystals from forming is:
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a.
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gabbro. |
b.
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granite. |
c.
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obsidian. |
d.
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pumice. |
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38.
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When the gases in high-silica magma “puff up” as the rock cools, ____ is formed.
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a.
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gabbro |
b.
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granite |
c.
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obsidian |
d.
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pumice |
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39.
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The size of the crystals of igneous rocks is determined by:
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a.
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melting speed |
b.
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cooling speed |
c.
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location |
d.
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time of day |
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40.
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Which of the following characteristics is most TRUE of igneous rocks formed underground?
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a.
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Small crystals |
b.
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Large crystals |
c.
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Gas bubbles |
d.
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Glassy appearance |
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41.
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Mauna Loa, located in Hawaii, is Earth’s largest volcano. Mauna Loa’s elevation above sea level is approximately 4,170 meters above sea level. However, it actually stands approximately 9,090 meters high because much of it stands in ocean below sea level. What percent of Mauna Loa is located above sea level?
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a.
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31% |
b.
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69% |
c.
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25% |
d.
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46% |
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42.
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The map shows a number of active volcanoes on the western coastline of South America, but there are no volcanoes on the eastern coastline. The explanation for this would be ........
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a.
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Volcanoes on the west coast are there because of the subducting Nazca plate. |
c.
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Volcanoes on the east coast are under water. |
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b.
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Only volcanoes on the west coast are active. |
d.
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Volcanoes on the west coast are there because of the divergent boundary between the Nazca plate and the S. American plate. |
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43.
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Assume Mt. St. Helens was approximately 2950 meters high prior to the 1980 eruption. If the eruption in 1980 reduced its height by 13.5% how high would it be after the eruption?
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a.
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398 m |
b.
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2552 m |
c.
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3348 m |
d.
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2655 m |
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Matching
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44.
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magma chamber
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45.
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secondary vent
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46.
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sill
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47.
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conduit
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48.
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horizontal movement of magma
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49.
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“neck” of volcano
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50.
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When this area cools over time and the ground around it erodes, it can become a granite dome like the ones found in Yosemite National Park.
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51.
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primary vent
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52.
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dike
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a.
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basalt |
g.
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pillow |
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b.
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lava |
h.
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strato volcano |
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c.
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hot spot |
i.
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active volcano |
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d.
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dormant |
j.
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cinder cone |
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e.
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magma |
k.
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shield volcano |
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f.
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caldera |
l.
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extinct volcano |
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53.
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When a volcano erupts, melted rock known as _________, leaves the underground chamber of the volcano.
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54.
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When magma reaches the surface, it is called ______________.
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55.
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A ________ is a large bowl-shaped depression in a volcano.
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56.
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_______ lava is a distinctive round lava formation that often forms along mid-ocean ridges.
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57.
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A volcanic chain is formed when a lithospheric plate moves over a _________.
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58.
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Explosive eruptions and pyroclastic flows come from ___________.
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59.
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Devil’s Tower is a good example of an ___________.
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60.
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Basaltic magma tends to form _________________.
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