1. The rate of cooling of a magma or lava is reflected by the ________ of the rock.

   mineralogy
   texture
   color
   density

2. The temperature (at least a minimum estimate) from which the melt cooled is reflected by the _________ of the rock.

   mineralogy
   texture
   color
   density

3. Where would you expect to find the largest crystals in a lava flow?

   near the top surface of the flow
   in the center of the flow
   near the bottom of the flow
   the crystals would have the same grain size throughout the flow

4. According to Bowen's reaction series, which of the following pairs of phases are likely to be incompatible?

   quartz and alkali feldspar
   Ca-Plagioclase and olivine
   quartz and olivine
   Na-plagioclase and amphibole

5. The last mineral (assuming that the composition is appropriate) to crystallize from a magma is:

   plagioclase
   olivine
   quartz
   pyroxene

6. The fine grained (aphanatic) equivalent of a granite is a:

   rhyolite
   gabbro
   andesite
   basalt

   

   Grains are alkali feldspar and quartz. The length of the figure is about 2 cm.

7. The diagram above most likely represents a ___________

   extrusive igneous rock
   intrusive igneous rock
   clastic sedimentary rock
   chemical sedimentary rock

8. The coarse grained equivalent of a basalt is a:

   rhyolite
   gabbro
   andesite
   basalt

9. Describe the plate tectonic settings where you would expect to find granitic/rhyolitic rocks:

   subduction zone
   continent/continent collision
   spreading center
   transform boundary

10. Describe the plate tectonic settings where you would expect to find andesites:

    subduction zone
    continent/continent collision
    spreading center
    transform boundary

11. Describe the plate tectonic settings where you would expect to find basaltic rocks:

    subduction zone
    continent/continent collision
    spreading center
    transform boundary

12. Which should offer the least resistance to flow - a basaltic lava, an andesitic liquid or a rhyolitic liquid?

    basalt
    andesite
    rhyolite
    

13. Which is more likely, a granite dike, a diorite dike or a gabbro dike?

    granite
    diorite
    gabbro
    

14. Which of the following minerals might be found in a granite dike?

    amphibole
    muscovite
    biotite
    all of these

15. Crater Lake, Oregon, is a lake within a:

    sill
    crater
    caldera
    volcanic neck

16. Residents at the base of which one of the following would face the greatest danger of a nuee ardente?

    shield volcano
    cinder cone
    geyser
    stratovolcano

17. The continental crust is most like _______________.

    granite
    rhyolite
    basalt
    gabbro

18. The oceanic crust is most like _______________.

    granite
    rhyolite
    basalt
    gabbro

19. What type of volcanic rock contains a large number of cavities (bubbles) that form when gases escape from the molten rock?

    granite
    obsidian
    pumice
    basalt

20. What is the effect of water on melting (assuming the rock does not contain any hydrous minerals)?

    water raises the melting temperature of rock
    water lowers the melting temperature of a rock
    water neither raises nor lowers the melting temperature
    

21. During crystallization of a melt plagioclase become richer in __________ .

    potassium
    sodium
    calcium
    krypton

22. At about what temperature do olivine and Ca-rich plagioclase crystallize from a magma?

    500 degrees C
    1000 degrees C
    1500 degrees C
    2000 degrees C

23. Which of the following is a concordant intrusive rock?

    dike
    sill
    stock
    batholith

24. What type of igneous rock would contain 10 mm long plagioclase crystals surrounded by 0.5 mm long crystals?

    porphyry
    obsidian
    phaneritic
    aphanitic

25. Which of the following pairs of intrusive and extrusive rocks have the same chemical composition?

    granite and andesite
    diorite and basalt
    gabbro and basalt
    gabbro and rhyolite

26. Which of the following best describes a granite?

    a light-colored, fine-grained igneous rock rich in silica
    a light-colored, fine-grained igneous rock poor in silica
    a light-colored, coarse-grained igneous rock rich in silica
    a light-colored, coarse-grained igneous rock poor in silica

27. Which of the following best describes a basalt?

    a dark-colored, fine-grained igneous rock rich in silica
    a dark-colored, fine-grained igneous rock poor in silica
    a dark-colored, coarse-grained igneous rock rich in silica
    a dark-colored, coarse-grained igneous rock poor in silica

28. Most igneous rocks contain ___________SiO₂ by weight.

    less than 40%
    between 40% and 70%
    between 70% and 90%
    greater than 90%

29. Which of the following minerals is the most abundant mineral in ultramafic rocks?

    amphibole
    olivine
    sodium plagioclase
    quartz

30. Which of the following statements about mafic rocks is true?

    mafic rocks are richer in silica than felsic rocks
    mafic rocks crystallize at higher temperatures than felsic rocks
    mafic rocks are more viscous than felsic rocks
    mafic rocks tend to be lighter in color than felsic rocks.

31. Which of the following igneous rocks crystallizes near the Earth's surface?

    basalt
    gabbro
    diorite
    granite

32. What is the approximate silica content of a granite?

    20%
    50%
    70%
    100%

33. Which of these minerals is commonly found in both mafic and felsic rocks?

    quartz
    alkali feldspar
    plagioclase feldspar
    olivine

34. Which of the following is NOT an extrusive igneous rock?

    basalt
    andesite
    obsidian
    granite

35. Felsic => Intermediate => =>Mafic
    Which of the following properties increases in the direction of the arrows in the sentence above?

    melting temperature
    potassium content
    silica content
    viscosity

36. What type of magma forms at mid-ocean ridges?

    basalt
    andesite
    ultramafic
    granite

37. A porphyritic igneous rock contains phenocrysts of olivine and calcium-rich plagioclase in an aphanitic groundmass. This is a __________?

    andesite porphyry
    basalt porphyry
    gabbro porphyry
    rhyolite porphyry

38. A porphyritic igneous rock contains phenocrysts of olivine and calcium-rich plagioclase in an phaneritic groundmass. This is a __________?

    andesite porphyry
    basalt porphyry
    gabbro porphyry
    rhyolite porphyry

39. What is the dominant rock type on most of the Hawaiian Islands?

    basalt
    andesite
    ultramafic
    granite

40. What is the dominant rock type at the center of the Sierra Nevada Mountains?

    basalt
    andesite
    ultramafic
    granite

41. What is the effect of water on melting?

    water raises the melting temperature of a rock
    water lowers the melting temperature of a rock
    water does not change the melting temperature of a rock
    this depends on how much water is present

    

42. Which of the following scenarios would lead to melting of Albite plus Water?

    raise the Pressure (P)
    raise the Temperature (T)
    either raise the Pressure (P) or raise the Temperature (T)
    decrease either the Temperature (T) or Pressure (P)

43. During crystallization of a magma the plagioclase feldspar __________.

    is replaced by quartz
    is replaced by pyroxene
    becomes richer in calcium
    becomes richer in sodium

44. Which mineral is not part of the discontinuous reaction series?

    plagioclase
    olivine
    pyroxene
    amphibole

45. At about what temperature do olivine and calcium-rich plagioclase crystallize from a melt? (answers are in degrees centigrade)

    500
    1000
    1500
    2000

46. Which of the following minerals crystallizes first from a basaltic magma?

    quartz
    biotite
    pyroxene
    olivine

47. How does a magma make space for itself in order to rise through the crust?

    by wedging open the overlying rock
    by breaking off large blocks that sink into the magma chamber
    by melting the surrounding rocks
    all of these

48. How can a sill be distinguished from a lava flow?

    a sill is generally coarser-grained than a lava flow
    the rocks above and below a sill will show evidence of heating but only the rocks below a lava flow will show evidence of heating
    sills generally do not have vesicles; lava flows generally have vesicles
    all of these

49. Which of the following is not a volcanic arc that overlies a subduction zone?

    Aleutian Islands
    Hawaiian Islands
    Cascade Range
    Japanese Islands

50. What type of silicate minerals on the discontinuous side of the reaction series crystallize at the highest temperatures?

    isolated tetrahedral
    single chain
    sheet
    framework

51. As a magma changes from mafic to felsic, which of the following elements decreases?

    sodium
    potassium
    silicon
    iron

52. Which of the following statements is false?

    mafic magmas are more viscous than felsic magmas
    mafic magmas are hotter than felsic magmas
    mafic magmas contain more calcium than felsic magmas
    mafic magmas contain less silicon than felsic magmas

53. Which of the following properties does not depend on the chemical composition of an igneous rock?

    grain size
    melting temperature
    mineralogy
    viscosity

54. Compared to felsic magmas, mafic magmas are relatively enriched in:

    calcium
    iron
    magnesium
    all of the above

55. A glassy texture indicates:

    very rapid cooling
    slow cooling
    slow followed by rapid cooling
    none of the above

56. Pyroclastic rocks form by:

    a lava cooling on the surface of the Earth
    violent, explosive volcanic eruption
    a magma cooling slowing in the subsurface
    two phases of cooling, one fast and one slow

57. The presence of phenocrysts in an igneous rocks indicate:

    a lava cooling on the surface of the Earth
    violent, explosive volcanic eruption
    a magma cooling slowing in the subsurface
    two phases of cooling, one fast and one slow

58. Vesicles in an igneous rock form from:

    escaping gases
    phenocrysts settle to the bottom of the magma chamber
    falling ash
    all of the above

59. The discontinuous branch of Bowen's reaction series consists of minerals with ________ structures.

    isolated tetrahedra
    single chains
    double chains
    all of the above

60. Batholiths are associated with:

    plateau basalts
    oceanic islands
    folded mountains
    all of the above

    

61. Which of the following rock types is depicted in the diagram above?

    basalt
    rhyolite
    gabbro
    diorite

    

62. Which of the following rock types is depicted in the diagram above?

    felsic
    intermediate
    mafic
    ultramafic

    

63. In the basalt sample depicted above, the vesicles (small spherical cavities) most likely formed by ___________.

    the escape of gas bubbles dissolved in the lave during eruption
    the weathering and erosion of olivine crystals after the eruption
    air bubbles entrained in the flow during the eruption
    vaporization during underwater eruption

    

64. What mineral occurs in box I of Bowen's Reaction Series (above)

    amphibole
    Ca-rich plagioclase
    olivine
    quartz

65. What mineral occurs at point II of Bowen's Reaction Series (above)

    Na-rich plagioclase
    Ca-rich plagioclase
    olivine
    quartz

66. What mineral occurs in box III of Bowen's Reaction Series (above)

    Na-rich plagioclase
    muscovite
    olivine
    quartz

    

67. Which of the following volcanic chains formed at a tectonic setting similar to "A"?

    Aleutian Islands
    Andes Mountains
    Cascade Range
    Hawaiian Islands

68. What type of lava is most likely to erupt at tectonic setting "B"?

    andesitic
    basaltic
    rhyolitic
    none of the above

69. Which of the following volcanoes formed at a tectonic setting similar to "C"?

    Hekla, Iceland
    Mauna Loa
    Mount Pelee, Martinique
    Mount St. Helens

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