Can You Pass This Hardest Geology Test? Quiz

59 Questions

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Geology Quizzes & Trivia

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Questions and Answers
  • 1. 
    • A. 

      Intrusive magma is cooler because it is well insulated by the surrounding rock.

    • B. 

      Intrusive magma flows onto the Earth's surface and cools very slowly, allowing many small mineral grains to grow.

    • C. 

      The extrusive magma cools quickly so the mineral grains do not have time to grow.

    • D. 

      The extrusive magma, because it is deep below the surface, cools very slowly producing very small mineral grains

  • 2. 
    Which magma is most likely to quench (congeal) to a natural glass? 
    • A. 

      Highly viscous; cools quickly

    • B. 

      Highly viscous; cools slowly

    • C. 

      Highly fluid; cools slowly

    • D. 

      Highly fluid; cools quickly

  • 3. 
    The sizes, shapes, and arrangements of mineral grains in an igneous rock is known as ________
    • A. 

      Silica content

    • B. 

      Texture

    • C. 

      Mineral content

    • D. 

      Bowen's reaction series

  • 4. 
    ________ magma cools and consolidates without growth of mineral grains 
    • A. 

      Aphanitic

    • B. 

      Porphyritic

    • C. 

      Phaneritic

    • D. 

      Glassy

  • 5. 
    ________ mineral grains are of roughly equal size and coarse enough to be seen without a microscope or magnifying glass  
    • A. 

      Aphanitic

    • B. 

      Porphyritic

    • C. 

      Phaneritic

    • D. 

      Glassy

  • 6. 
    ________ rock has two or more, distinctly different-sized populations of mineral grains  
    • A. 

      Aphanitic

    • B. 

      Porphyritic

    • C. 

      Phaneritic

    • D. 

      Glassy

  • 7. 
    ________ a magnifying glass or microscope is needed to see individual mineral grains 
    • A. 

      Aphanitic

    • B. 

      Porphyritic

    • C. 

      Phaneritic

    • D. 

      Glassy

  • 8. 
    A ________ is an open cavity in a volcanic rock that was filled by a gas bubble when the lava was still mainly liquid.
    • A. 

      Porphyrocryst

    • B. 

      Vesicle

    • C. 

      Phenocryst

    • D. 

      Xenocryst

  • 9. 
    Consider the Bowen's reaction series. Which mineral would you expect to see as a phenocryst in a porphyritic basalt? 
    • A. 

      Olivine

    • B. 

      Quartz

    • C. 

      Orthoclase

    • D. 

      Sodium-rich plagioclase

  • 10. 
    Which of the following igneous rocks exhibit aphanitic texture? 
    • A. 

      granite; gabbro

    • B. 

      Andesite; rhyolite

    • C. 

      Andesite; diorite

    • D. 

      Rhyolite; gabbro

  • 11. 
    In a porphyritic volcanic rock, which mineral grains are the last to crystallize? 
    • A. 

      Phenocrysts

    • B. 

      Vesicles

    • C. 

      Pegmatites

    • D. 

      Matrix or groundmass

  • 12. 
    Visible quartz and potassium feldspar grains are the main constituents in a ________. 
    • A. 

      Granite

    • B. 

      Gabbro

    • C. 

      Basalt

    • D. 

      Rhyolite

  • 13. 
    Which of the following igneous rocks has a pyroclastic texture? 
    • A. 

      Rhyolitic tuff

    • B. 

      Porphyritic basalt

    • C. 

      Intrusive granite

    • D. 

      Andesitic lava

  • 14. 
    ________ is a volcanic rock that is extremely vesicular and glassy. 
    • A. 

      Obsidian

    • B. 

      Pegmatite

    • C. 

      Tuff

    • D. 

      Pumice

  • 15. 
    ________ is composed mainly of ferromagnesian minerals. 
    • A. 

      Peridotite

    • B. 

      Rhyolite

    • C. 

      Andesite

    • D. 

      Granite

  • 16. 
    Which of the following minerals crystallize early in Bowen's reaction series? 
    • A. 

      Biotite

    • B. 

      Quartz

    • C. 

      Olivine

    • D. 

      Muscovite

  • 17. 
    ________ is the dominant feldspar in basalt. 
    • A. 

      Plagioclase

    • B. 

      Microcline

    • C. 

      Orthoclase

    • D. 

      Pyroxene

  • 18. 
    Which of the following are used for studying rocks with a polarizing microscope? 
    • A. 

      Polished cubes

    • B. 

      Broken chips

    • C. 

      Thin sections

    • D. 

      Grain karats

  • 19. 
    ________ is characterized by very coarse mineral grains? 
    • A. 

      Obsidian

    • B. 

      Pumice

    • C. 

      Pegmatite

    • D. 

      Granite

  • 20. 
    In which of the following igneous rocks and environments would you expect to find unusually high concentrations of rare elements such as lithium, beryllium, and boron? 
    • A. 

      Basalt dike; fills a vertical fracture at shallow depth

    • B. 

      Pumice lump; crystallized at depth in a mass of intrusive granite

    • C. 

      Peridotite; crystallized at depth in the upper mantle

    • D. 

      Pegmatite; crystallized from a water-rich, highly differentiated, residual magma

  • 21. 
    A (an) ________ texture represents a single, long period of cooling and crystallization. 
    • A. 

      Glassy

    • B. 

      Pyroclastic

    • C. 

      Aphanitic

    • D. 

      Phaneritic

  • 22. 
    ________ has the same mineral composition as andesite? 
    • A. 

      Basalt

    • B. 

      Granite

    • C. 

      Gabbro

    • D. 

      Diorite

  • 23. 
    What do pumice and obsidian have in common?
    • A. 

      Basaltic composition

    • B. 

      Glassy texture

    • C. 

      Ultramafic composition

    • D. 

      Phaneritic texture

  • 24. 
    Which of the following best describes an aphanitic texture? 
    • A. 

      The rock is crystalline; mineral grains are too small to be visible without a magnifying lens or microscope

    • B. 

      The mineral grains have glassy textures.

    • C. 

      The rock consists of broken, volcanic-rock and mineral fragments.

    • D. 

      The rock is crystalline; mineral grains are of distinctly different sizes.

  • 25. 
    A ________ texture would be most unlikely to occur in an extrusive igneous rock. 
    • A. 

      Pyroclastic

    • B. 

      Glassy

    • C. 

      Aphanitic

    • D. 

      Phaneritic

  • 26. 
    ________ is named for a prominent, volcanic mountain range in western South America. 
    • A. 

      Basalt

    • B. 

      Andesite

    • C. 

      Pegmatite

    • D. 

      Peridotite

  • 27. 
    ________ is the dominant lava erupted from volcanoes on Hawaii and Iceland. 
    • A. 

      Rhyolite

    • B. 

      Andesite

    • C. 

      Peridotite

    • D. 

      Basalt

  • 28. 
    Which igneous rock or magma has the lowest silica (SiO2) content? 
    • A. 

      Granite

    • B. 

      Basalt

    • C. 

      Andesite

    • D. 

      Peridotite

  • 29. 
    ________ is thought to be common in the Earth's mantle but rare in the crust? 
    • A. 

      Pumice

    • B. 

      Grante

    • C. 

      Pegmatite

    • D. 

      Peridotite

  • 30. 
    ________ often contain gem-quality crystals of minerals such as beryl and tourmaline and high concentrations of relatively rare elements such as lithium, boron, and beryllium.
    • A. 

      Welded tuff sheets

    • B. 

      Basaltic lavas

    • C. 

      Granitic pegmatites

    • D. 

      Diorite plutons

  • 31. 
    The last minerals to crystallize on Bowen's Reaction Series result in igneous rocks with a ________ composition. 
    • A. 

      Felsic

    • B. 

      Intermediate

    • C. 

      Mafic

    • D. 

      Ultramafic

  • 32. 
    Changing the composition of magma by incorporating surrounding host rock is known as ________
    • A. 

      Magma mixing

    • B. 

      Partial melting

    • C. 

      Differentiation

    • D. 

      Assimilation

  • 33. 
    All of the following are factors that affect the generation of magma except for ________. 
    • A. 

      Heat

    • B. 

      Pressure

    • C. 

      Crystal size

    • D. 

      Volatiles

  • 34. 
    Bowen's reaction series predicts the sizes of the different mineral grains that grow from crystallizing magmas. 
    • A. 

      True

    • B. 

      False

  • 35. 
    In an igneous rock with a phaneritic texture, the mineral grains are visible to the unaided eye. 
    • A. 

      True

    • B. 

      False

  • 36. 
    Olivine and quartz commonly crystallize together from mafic or basaltic magmas. 
    • A. 

      True

    • B. 

      False

  • 37. 
    Most lava crystallizes to form igneous rocks with phaneritic textures. 
    • A. 

      True

    • B. 

      False

  • 38. 
    Pegmatites are smaller volume, intrusive bodies with glassy textures. 
    • A. 

      True

    • B. 

      False

  • 39. 
    Basalt is the aphanitic or fine-grained equivalent of gabbro. 
    • A. 

      True

    • B. 

      False

  • 40. 
    Plutonic rocks are intrusive and generally consist of mineral grains coarse enough to be readily visible in a hand sample. 
    • A. 

      True

    • B. 

      False

  • 41. 
    A porphyritic texture includes two different sizes of mineral grains, the phenocrysts and the vesicles. 
    • A. 

      True

    • B. 

      False

  • 42. 
    Olivine is an important mineral in peridotites and other ultramafic rocks. 
    • A. 

      True

    • B. 

      False

  • 43. 
    The process of magmatic differentiation can generate residual, more felsic magmas from mafic magmas such as basalt. 
    • A. 

      True

    • B. 

      False

  • 44. 
    Glassy igneous rocks form when magma cools too fast for mineral grains to grow. 
    • A. 

      True

    • B. 

      False

  • 45. 
    Minerals, such as plagioclase feldspar, on the continuous branch of Bowen's Reaction Series react with the magma to form lower temperature, more stable minerals such as hornblende or biotite.  
    • A. 

      True

    • B. 

      False

  • 46. 
    A feldspar crystal where a calcium rich interior is surrounded by a sodium rich rim indicates that there was incomplete reaction between the crystal and surrounding magma 
    • A. 

      True

    • B. 

      False

  • 47. 
    Andesitic magma can form through differentiation of granitic magma 
    • A. 

      True

    • B. 

      False

  • 48. 
    Consider Bowen's reaction series. Which mineral would you expect to see as a phenocryst in a porphyritic basalt?
    • A. 

      Olivine

    • B. 

      Quartz

    • C. 

      Orthosclase feldspar

    • D. 

      Sodium-rich plagioclase feldspar

  • 49. 
    What texture describes an igneous rock that has two or more distinctly different-sized populations of mineral grains? 
    • A. 

      Porphyritic

    • B. 

      Phaneritic

    • C. 

      Aphanitic

    • D. 

      Glassy

  • 50. 
    Which of the following igneous rocks has a phaneritic texture? 
    • A. 

      Andesite

    • B. 

      Rhyolite

    • C. 

      Basalt

    • D. 

      Gabbro

  • 51. 
    The formation of a secondary magma of different composition from a parent magma is called magmatic differentiation 
    • A. 

      True

    • B. 

      False

  • 52. 
    What type of magma, commonly erupted along oceanic ridge systems, originates by partial melting of mantle peridotite? 
    • A. 

      Ultramafic

    • B. 

      Andesite

    • C. 

      Basalt

    • D. 

      Rhyolite

  • 53. 
    Which of the following pairs of igneous rocks have the same composition? 
    • A. 

      Rhyolite and gabbro

    • B. 

      Rhyolite and granite

    • C. 

      Andesite and peridotite

    • D. 

      Basalt and diorite

  • 54. 
    What is the name of a volcanic rock that is extremely vesicular and glassy?
    • A. 

      Obsidian

    • B. 

      Pumice

    • C. 

      Tuff

    • D. 

      Pegmatite

  • 55. 
    All of the following are factors that affect the generation of magma except for _____________ 
    • A. 

      Crystal size

    • B. 

      Heat

    • C. 

      Pressure

    • D. 

      Volatiles

  • 56. 
    Which of the following factors or processes influence the composition of magma? 
    • A. 

      Composition of the original rock that melted to form the magma

    • B. 

      Types of minerals that crystallize from magma

    • C. 

      Mixing of magmas having different compositions

    • D. 

      Composition of any host rock assimilated by the magma

    • E. 

      All answer choices.

  • 57. 
    On the basis of Bowen's reaction series, which of the following minerals has the lowest melting temperature?
    • A. 

      Calcium-rich plagioclase feldspar

    • B. 

      Pyroxene

    • C. 

      Amphibole

    • D. 

      Quartz

  • 58. 
    On the basis of the figure, which of the following statements is most accurate?
    • A. 

      Wet granite melts at a higher temperature than dry granite

    • B. 

      Dry basalt melts at a higher temperature than dry granite

    • C. 

      Basalt and wet granite melt at the same temperature

    • D. 

      Whether granite is wet or dry has no effect on melting temperature

  • 59. 
    Decompression melting in the generation of magma is common along... 
    • A. 

      Convergent plate boundaries

    • B. 

      Mid-ocean ridges

    • C. 

      Transform faults

    • D. 

      Oceanic trenches