Introduction to Geology

Introduction to Geology

Quiz 7 - Igneous Rocks and Processes

1. The geothermal gradient is:
a. the change 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 contribute to formation of magma?
a. a decreases in pressure (such as caused by an earthquake)
b. an introduction of volatiles (water, gases) under high pressure
c. an increased rate of heat flow
d. all of the above


3. Processes involving with magma moving, cooling, and crystalizing underground is called:
a. volcanism.
b. plutonism.
c. fumeroles.
d. phaneritic.

4. What factors causes volcanic eruptions?
a. Magma below the surface is under extreme pressure created by the weight of the rock above it.
b. Magma is under pressure from of gases dissolved within it.
c. Magma of granitic composition can have as much at 5 percent water dissolved in it that can explode into steam at the surface.
d. all of the above

5. What is the rock composition of the volcanoes with the hotest lava?
a. basalt
b. andesite
c. dacite
d. rhyolite

6. What is the rock composition of the volcanoes that typically produce very large, catastrophic explosive eruptions, with potentially the greatest regional ash fall coverage?
a. basalt
b. andesite
c. dacite
d. rhyolite

7. Lava that cools and crystallizes quickly on the surface are called extrusive igneous rocks. These rocks tend to have what kind of texture?
a. Phaneritic, having small crystals and a very coarse-grained texture.
b. Phaneritic, having large crystals and a very fine-grained texture.
c. Aphanitic, having large crystals and a very coarse-grained texture.
d. Aphanitic, having very small crystals and a very fine-grained texture.

8. How are different kinds of igneous rocks named? Their naming classification is based on:
a. mineral composition.
b. crystalline sizes.
c. general color.
d. textural characteristics.
e. all of the above.

9. As a molten body of magma cools, high-temperature minerals crystallize first and low-temperature minerals crystallize last. As the high-temperature minerals form (mafic minerals crystallize first) and this causes the chemical composition to gradually change until the low-temperature minerals crystallize last (felsic minerals crystallize last). According to Bowen's reaction series, what minerals are likely to crystallize first?
a. quartz and muscovite mica.
b. olivine and pyroxene.
c. sodium-rich feldspar.
d. amphibole and biotite mica.

10. According to Bowen's reaction series. What is the last minerals to crystallize as a body of molten rock cools?
a. quartz and muscovite mica.
b. olivine and pyroxene.
c. sodium-rich feldspar.
d. amphibole and biotite mica.

11. Granitic rocks (rocks having a granite-like appearance and general composition) is what type of rock?
a. felsic
b. intermediate
c. mafic
d. ultramafic

12. Volcanic and plutonic rocks associated with volcanic arcs, such as the volcanoes of the Cascades Range in Washington, Oregon, and northern California, or volcanic island arcs like Japan or Alaska's Aleutian Islands volcanic are are mostly what type of rock?
a. felsic
b. intermediate
c. mafic
d. ultramafic

13. Rocks formed from very hot magma derived from the upper mantle, or rocks from the upper mantle itself are mostly of what type of rock or mineral composition?
a. felsic
b. intermediate
c. mafic
d. ultramafic

14. A volcanic rock that has a ropey, fluid-like texture formed from the rapid cooling of very hot basaltic lava is called:
a. a'a.
b. pahoehoe.
c. scoria.
d. tuff.

15. A rock that is a natural form of glass or has a glass-like appearance that displays a conchoidal fracture on freshly broken surfaces is called:
a. scoria.
b. flow- banded lava rock.
c. obsidian.
d. tuff.

16. Sometime a rock from the margins or the roof of a magma chamber sinks into the molten material, and does not completely melt, or it may be carried along with the molten material as it flows. The name of a rock fragment that is foreign to the igneous mass in which it occurs is called a:
a. xenolith.
b. porphyry.
c. phenocryst.
d. pegmatite.

17. The term tephra refers to:
a. a variety of lava that spews from a volcano.
b. ash, cinders, and rock fragments ejected from a volcanic eruption.
c. steam and gases vented from a volcano.
d. a vent on a volcano where lava erupts.

18. What kind of volcanic cone forms from very hot and fluid lavas pouring out on the surface, such as on Hawaii?
a. cinder cone
b. shield volcano
c. stratovolcano
d. dome volcano

19. A very large volcanic crater typically one formed my a major eruption or the inward collapse of a volcanic cone following an eruption is called a:
a. trap.
b. caldera.
c. fissure.
d. composite cone.

20. What is the name of a great mass of igneous rock, extending to great depths, formed from extensive magmatic intrusions (plutons) over a long period of time and throughout a region, typically associated with volcanic arcs. An example would be the great mass of the Sierra Nevada Range in California.
a. pluton.
b. intrusion.
c. batholith.
d. hotspot.

21. What is the name for a vertical or near vertical wall of igneous rock formed where magma squeezed into a fault zone or fracture before cooling and crystallizing. When later exposed by erosion often appear as dark castle wall-like features on landscapes.
a. stock
b. laccolith
c. dike
d. sill

22. An opening or vent in or near a volcano, through which hot sulfurous gases, steam, and other gases emerge is called:
a. a fumerole.
b. a hot spring.
c. a geyser.
d. a black smoker.

23. A type of hot spring in which water intermittently boils and erupts, sending a tall column of water and steam into the air is called:
a. a fumerole.
b. a white smoker.
c. a geyser.
d. a black smoker.

24. A dense cloud of very hot ash, lava fragments, and gases ejected explosively from a volcano and typically flowing downslope at great speed and with destructive force is called a:
a. pyroclastic flow.
b. lahar.
c. volcanic tuff.
d. ignimbrite.

25. What is the name landslide or mudflow of volcanic materials on the flanks of a volcano? It is also the name of the deposit created by a landslide or mudflow on a volcanic landscape.
a. pyroclastic flow
b. lahar
c. volcanic tuff
d. ignimbrite

26. Diamonds are often found in association with a special kind of intrusive igneous rock called:
a. a kimberlite.
b. a pegmatite.
c. an aureole zone.
d. a xenolith.

27. 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) that is often host exotic and important minerals, including many gemstones, is called:
a. a diatreme.
b. a pegmatite.
c. an aureole zone.
d. an aplite.

Clues where to find answers.

http://gotbooks.miracosta.edu/geology/quiz/quiz7.html
12/6/2017