Geology Exam
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Geology exam #2
- 1.Once a mass of magma is created, the magma's composition cannot be changed
- A.
True
- B.
False
- 2.Extrusive igneous rocks are also called ___, while intrusive rocks are also called ___.
- A.
Plutonic, volcanic
- B.
Volcanic, plutonic
- C.
Plutonic, granite
- D.
Volcanic, basalt
- 3.What is a fundamental difference in chemical compostion between the igneous rocks granite and basalt?
- A.
There is no difference
- B.
One rock contains abundant silicon and one rock contains none
- C.
One contains abundadant ferromagnesian minerals and the other has almost none
- 4.Which of these is a common felsic igneous rock?
- A.
Quartz
- B.
Travertine
- C.
Basalt
- D.
Granite
- 5.__________ is the dominant rock type being erupted as lava flows at the crests of Earth's oceanic ridge systems, such as in the Atlantic Ocean east of North Carolina.
- A.
Granite
- B.
Pegmatite
- C.
Basalt
- D.
Quartz
- 6.Most magma generated on earth
- A.
Stays below the surface and forms intrusions
- B.
Sings to the core-mantle boundary because of it's magnetism
- C.
Erupts at the surface and forms volcanic rocks
- 7.Gasses (volatiles) escaping from magma will produce vesicles (voids or bubbles) in the solified rock. Which of these is not an example of vesicular texture?
- A.
Scoria basalt
- B.
Rhyolite
- C.
Granite pegmatite
- 8.What does the term "pyroclastic" mean?
- A.
Any volcanic eruption of a non-silicate magma
- B.
Unusually fluid lava flows
- C.
High-quality obsidian used to make arrowheads and spear points
- D.
"fire broken" materials erupted by a volcano
- 9._____ is the primary "driving force" behind volcanic eruptions.
- A.
Magnetism
- B.
Temperature
- C.
Escaping volatiles (gasses)
- D.
Pluto, the Greek god of the underworld
- 10.A sample of Hawaiian basalt is shown on the left side of the front projection screen. Which of the following igneous textures is not displayed by this rock?
- A.
Vesicular (or scoria)
- B.
Phaneritic
- C.
Aphanitic
- D.
Porphyritic
- 11.The primary control on the style of volcanic eruption (quiet versus violent) is
- A.
Depth to the subduction zone
- B.
Height of the volcano
- C.
Magma viscosity
- D.
Magnetism
- 12.Cinder cones are
- A.
Relatively small steep sided volcanoes
- B.
Typically composed of basalt
- C.
Built from ash, cinders, and other pyroclastic materials
- D.
All of the above
- E.
Only A and B
- 13.What kind of volcanic material is erupted at the crest of a mid-ocean ridge?
- A.
Pillow lavas
- B.
Welded tuff
- C.
Andesite lava domes
- D.
Carbonatite hornitos
- 14.____ is the most dangerous type of volcanic activity.
- A.
Rhyolite pyroclastic flows
- B.
Basalt lava fountains
- C.
Basalt pahoehoe flows
- D.
Carbonatite hornitos
- 15.Which type of basalt lava flow is shown on the right side of the front projection screen?
- A.
Aa
- B.
Pahoehoe
- C.
Welded tuff
- D.
Quartz
- 16.A shield volcano
- A.
Sunset Crater, Arizona
- B.
Yellowstone, Wyoming
- C.
Shiprock, New Mexico
- D.
Mauna Loa, Hawaii
- E.
Mt. St. Helens, Washington
- 17.The igneous plumbing of an extinct volcano
- A.
Sunset Crater, Arizona
- B.
Yellowstone, Wyoming
- C.
Shiprock, New Mexico
- D.
Mauna Loa, Hawaii
- E.
Mt. St. Helens, Washington
- 18.A very large caldera
- A.
Sunset Crater, Arizona
- B.
Yellowstone, Wyoming
- C.
Shiprock, New Mexico
- D.
Mauna Loa, Hawaii
- E.
Mt. St. Helens, Washington
- 19.A cinder cone
- A.
Sunset Crater, Arizona
- B.
Yellowstone, Wyoming
- C.
Shiprock, New Mexico
- D.
Mauna Loa, Hawaii
- E.
Mt. St. Helens, Washington
- 20.A stratovolcano
- A.
Sunset Crater, Arizona
- B.
Yellowstone, Wyoming
- C.
Shiprock, New Mexico
- D.
Mauna Loa, Hawaii
- E.
Mt. St. Helens, Washington
- 21.Mt. St. Helens is a dormant volcano, which means that it
- A.
Will not erupt again
- B.
Is now classified as a sedimentary rock deposit
- C.
Can only erupt pyroclastic flows approximately once per million years
- D.
Will erupt again in the future
- 22.A ______ typically results from a major eruption of hundreds of cubic miles of hot ash.
- A.
Shield volcano
- B.
Cinder cone
- C.
Caldera
- 23.A ______ is a volcanic mudflow that can be a very serious volcanic hazard.
- A.
Lahar
- B.
Fumarole
- C.
Caldera
- D.
Pahoehoe
- 24.The 1883 eruption of Krakatoa in Indonesia caused several large tsunami that killed thousands of people.
- A.
True
- B.
False
- 25.Earth's climate is simply too stable to be influenced by large volcanic eruptions
- A.
True
- B.
False
- 26.The largest masses of igneous intrusive rocks (plutons) exposed at Earth's surface are _________ composed of granite
- A.
Sills
- B.
Dikes
- C.
Laccoliths
- D.
Batholiths
- 27.A dike is a type of igneous pluton that is _______ relative to the structure or layering of the older rocks that were intruded by the dike.
- A.
Convergent
- B.
Divergent
- C.
Concordant
- D.
Discordant
- 28.How can hot rocks of Earth's mantle be caused to melt and create basaltic magma?
- A.
They can't- it is impossible to melt mantle rocks
- B.
Reduce the concentration of water and other volatiles
- C.
Reduce the confining pressure on the hot rocks
- D.
Reduce the temperature of the rocks
- 29.Much of the ______ Ocean basin is rimmed by active subduction zones, therefore it has most of Earth's ______ located around it's margins.
- A.
Pacific, shield volcanoes
- B.
Atlantic, shield volcanoes
- C.
Pacific, composite cones
- D.
Atlantic, composite cones
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