Introduction: Volcanoes have affected Earth from the beginning and mountain building has been occurring since Earth time began. Both influence Earth: they affect the atmosphere, the temperature, oceans, and our life.
I. Place the answers to the following sections on the lines along the left margin.
A. The following statements are true or false. Place a T or F on the lines to
indicate your decision.
______ 1. Currently, more than 1500 volcanoes on Earth are classified as active.
______ 2. Some volcanoes give indicators suggesting an eruption is likely.
______ 3. Some lava flows at speeds of 19 m/hr. or more.
______ 4. Towns located near a volcano are more likely to be covered with ash
than lava.
______ 5. Thousands of people have died from carbon dioxide emitted by a volcano.
______ 6. Relatively cool lava flows more rapidly than hot lava.
______ 7. Lava is simply magma that’s at Earth’s surface.
______ 8. The chemical content of magma is more important than temperature in
determining the viscosity of lava.
______ 9. Magma’s viscosity determines the type of eruption that a volcano has.
______10. Most volcanoes above sea level occur at rift zones.
______11. Volcanoes are never located in the interior of continents.
______12. Different plate boundaries produce different magma compositions because
each area has a different source rock.
______13. Silica-rich minerals have a lower melting temperature than silica-poor
minerals.
______14. Rhyolitic magma, the most viscous type of magma, is formed from partial
melting of the continental crust.
______15. The continental U. S. has four active volcanoes.
______16. Once the VEI (= volcanic explosivity index) is established for a volcano, it
never changes.
______17. The year without summer that occurred in 1815 was the result of a
volcanic eruption.
_____ 18. Yellowstone Park, a huge volcano sitting on a hot spot, will never erupt
again.
_____ 19. The continental crust is generally thinnest below mountain belts and
thickest at the margins of continents.
_____ 20. Isostasy compensates for added material by building a bigger submerged
root, and for lost material by raising the pile.
_____ 21. Mountains including volcanoes affect climates.
B. Select the word that best completes the following statements. Helpful words
are provided.
Helpful Words: basaltic, caldera, continental, convergent, duration, folding,
geysers, lahar, isostasy, magma, margins, monsoon, plateau, pyroclastic,
rhyolitic, silica, sinking, tephra, viscosity, water
______________ 1. The resistance of a liquid to flow is called ________.
______________ 2. Magma contains dissolved gases such as _____ vapor, carbon
dioxide, sulfur dioxide and others.
______________ 3. Three main types of lava are basaltic, andesitic, and ______.
______________ 4. The amount of ______ in lava partially determines the viscosity
and how violently a volcano will explode.
______________ 5. Most of the world’s active volcanoes above sea level are located
along ______ plate boundaries.
______________ 6. Rift zones always have ______ lava.
______________ 7. Rhyolitic magma, the most viscous type of magma, has a high
silica continent and is formed from the partial melting of _____
crust.
______________ 8. The volume of erupted material, _____ of the event, and height
ash reaches in the atmosphere all contribute to determining the
explosivity rank of an eruption.
______________ 9. Particles of all sizes that are blasted into the air by volcanic
eruptions are called __________.
______________10. A _____ flow consists of a dense mixture of hot volcanic debris
and gases that flow rapidly down the slope of a volcano.
______________11. ______ is molten rock, gases, and partially crystallized minerals
underground.
______________12. A mud flow that includes volcanic debris and water is known as a
_____.
______________ 13. A _______ is large crater formed when the top of the volcano
collapses into an empty magma chamber below the volcano.
______________ 14. The continental crust is generally thickest below mountain belts
and thinnest at the continental ________.
______________ 15. A balance between the topography of Earth’s surface and the
thickness and density of the underlying rocks is called _______.
______________ 16. When water-laden air rises over mountains, and rain falls, we say
that a ________ has occurred.
______________ 17. When water-laden air rises over mountains producing rain fall,
we say that a __________ has occurred.
______________ 18. Three processes create most mountains, ______, faulting and
volcanoes.
______________ 19. Low-viscosity lavas that reach the surface through fissures may
form a lava _____.
______________ 20. Groundwater circulating near hot magma can result in the
formation of several different features; one of these is ______.
II. Answer the following as indicated.
A. List three indicators that suggest a volcano is likely to erupt soon.
__________________________________________________________________________
___________________________________________________________________________
___________________________________________________________________________
B. Complete the following diagram.
Helpful Words: basalt, basalt to rhyolite, centuries, extremely large, large to very large, lava and pyroclastics, less violent, Mauna Loa, Mt. St. Helens, Paricutin, primarily lava, primarily pyroclastics, rhyolite to diorite, small to medium, tens of thousands of years, thousands, violent, violent to less violent.
| Volcano Type
Attributes |
Composite Cone | Shield Cone | Cinder Cone |
| Composition | |||
| Type of lava | |||
| Length of life | |||
| Eruption Type | |||
| Size | |||
| Example |
C. Review the name of following parts in this diagram.
Helpful words: batholith, cinder cone, conduit, dike, laccolith, magma
chamber, old dike, old lava flow, old volcanic neck, sill, volcano
A. ______________________
B. ______________________
C. ______________________
D. ______________________
E. ______________________
F. ______________________
G. ______________________
H. ______________________
I. ______________________
J. ______________________
K. ______________________
K
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