Introduction to Earth Science

Introduction to Earth Science

Quiz 8 - Igneous Rocks & Volcanic Activity

1. The geothermal gradient is:
a. the changes in temperature that increases with depth.
b. averages 20 to 30 degrees C per kilometer in the upper crust.
c. can vary significantly from one location to another.
d. all of the above.

2. What process (or processes) can generate magma?
a. increased rate of heat flow
b. decreases in pressure (such as caused by an earthquake)
c. introduction of volatiles (water, gases) under high pressure
d. all of the above

3. When molten material crystallizes deep underground, the geologic feature is called:
a. an extrusive igneous rock.
b. volcanism.
c. a pluton.
d. all of the above.

4. What are the 2 dominant gases released by a volcanic eruption?
a. SO2 and H2S
b. CO2 and SO2
c. H2O and SO2
d. H2O and CO2

5. The hottest lava observed on the Earth surface are associated with:
a. composite volcanoes, like Mount St. Helens in the Cascades volcanic arc.
b. oceanic hotspots, like Kilauea volcano on Hawaii.
c. island arc volcanoes, like Mount Pelee on the Caribbean island of Martinique.
d. continental rift zones, like the East African Rift volcanoes like Erta Ale, Ethiopia.

6. Which factors help produce the texture and appearance of igneous rocks?
a. the amount of dissolved gases in magma.
b. the amount of silica present.
c. the rate at which magma cools.
d. all choices are correct.

7. Igneous rocks are classified based on:
a. mineral composition.
b. crystal sizes.
c. general color and textural characteristics.
d. all choices are correct.

8. The igneous process called magmatic differentiation allows different kinds of rocks to form from an original single source of magma. What is main reason this occurs?
a. high-temperature minerals crystallize first.
b. low-temperature minerals crystallize first.
c. high temperature minerals crystallize last.
d. all choices are correct.

9. According to Bowen's reaction series, which of the following minerals has the highest crystallization temperature?
a. biotite
b. quartz
c. olivine
d. potassium feldspar

10. Which of these rock types contain the most quartz?
a. granite
b. andesite
c. gabbro
d. basalt

11. Which of these rock types has a fine-grained texture?
a. diorite
b. granite
c. gabbro
d. basalt

12. Which of these is an ultramafic rock?
a. diorite
b. rhyolite
c. andesite
d. peridotite

13. A dark, glass-like volcanic rock formed by the rapid solidification of lava without crystallization is:
a. tuff.
b. obsidian.
c. pahoehoe.
d. a'a.

14. A hard igneous rock containing visible crystals (phenocrysts), usually of feldspar, in a fine-grained (microcrystalline) mineral matrix—typically a dark gray, reddish, or purplish ground mass—is called.
a. a porphyry.
b. a xenolith.
c. a pegmatite.
d. an inclusion.

15. The large volcanoes on Hawaii including Kilauea, Mauna Loa, and Halualai volcanoes are what kind of volcano?
a. cinder cones.
b. shield cones.
c. composite cones.
d. fissure eruptions.

16. A great mass of igneous rock, extending to great depths, formed from extensive magmatic intrusions (plutons) over a long period of time and may extend throughout a region, typically associated with volcanic arcs, is called:
a. a batholith.
b. a hotspot.
c. a volcanic field.
d. a laccolith.

17. Devils Tower, Wyoming (used in the movies Close Encounters of a Third Kind and Paul) is an example of a:
a. sill
b. stock
c. dike
d. palisade

18. An opening or vent on or near a volcano that releases hot sulfurous gazes, steam and other gases is called:
a. a hot spring.
b. a geyser.
c. a fumerole.
d. a black smoker.

19. The general term used to describe rock fragments and particles ejected by a volcanic eruptions is called:
a. tephra.
b. lapilli.
c. cinders.
d. tuff.

20. A coarsely-grained crystalline igneous rocks with interlocking crystals typically several centimeters in length (or larger, including the world’s largest crystals, some larger than 10 meters in length) is called:
a. a diatreme.
b. a kimberlite.
c. a pegmatite.
d. an aureole.