Foundations of Earth Science, 6e (Lutgens) Chapter 2 Rocks: Materials of the Solid Earth

1) An igneous rock that contains vesicles ________.A) is also extrusiveB) is also fine grainedC) contains many small holesD) all of the aboveAnswer: DDiff: 1

2) As the rate of cooling increases, the size of the crystals that form ________.A) increasesB) decreasesC) is not affectedD) none of theseAnswer: BDiff: 1

3) Which one of the following is an igneous rock?A) limestoneB) rhyoliteC) slateD) shaleAnswer: BDiff: 1

4) Intrusive rocks ________.A) are generally fine-grainedB) form at Earth's surfaceC) are quite often vesicularD) none of the aboveAnswer: DDiff: 1

5) Granite and gabbro ________.A) have a similar mineral compositionB) have a similar textureC) both A and BD) are in no way similarAnswer: BDiff: 1

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6) Obsidian exhibits a(n) ________ texture.A) fine-grainedB) glassyC) coarse-grainedD) porphyriticAnswer: BDiff: 1

7) Rocks that contain crystals that are roughly equal in size and can be identified with the unaided eye are said to exhibit a ________ texture.A) fine-grainedB) glassyC) coarse-grainedD) porphyriticAnswer: CDiff: 1

8) This igneous texture is characterized by two distinctively different crystal sizes.A) fine-grainedB) glassyC) coarse-grainedD) porphyriticAnswer: DDiff: 1

9) Rhyolite is the fine-grained equivalent of this igneous rock.A) basaltB) andesiteC) graniteD) dioriteAnswer: CDiff: 1

10) Select the coarse-grained rock which is composed mainly of quartz and potassium feldspar from the list below.A) basaltB) andesiteC) graniteD) dioriteAnswer: CDiff: 1

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11) Which of the rocks listed below is a popular building stone?A) basaltB) andesiteC) graniteD) dioriteAnswer: CDiff: 1

12) The texture of an igneous rock ________.A) is controlled by the composition of magmaB) determines the color of the rockC) is caused by leachingD) records the rock's cooling historyAnswer: DDiff: 1

13) Igneous rock is formedA) by the weathering of pre-existing rocks.B) by changes in mineral composition.C) at great depth within Earth.D) by crystallization of molten rock.Answer: DDiff: 1

14) The most important mechanical weathering process is ________.A) frost actionB) hydrolysisC) unloadingD) thermal expansionAnswer: ADiff: 1

15) Chemical weathering would be most effective ________.A) in a warm, dry climateB) in a cold, dry climateC) in a warm, humid climateD) equally in any kind of climateAnswer: CDiff: 1

16) Which of the following is NOT a product of the chemical weathering of potassium feldspar?A) silicaB) potassium ionsC) iron oxideD) clayAnswer: CDiff: 1

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17) Which one of the following is NOT true about mechanical weathering?A) produces smaller piecesB) adds to the effectiveness of chemical weatheringC) does not change the rock's mineral compositionD) does not affect metamorphic rocksAnswer: DDiff: 1

18) Which one of the following is NOT related to chemical weathering?A) decompositionB) frost wedgingC) hydrolysisD) oxidationAnswer: BDiff: 1

19) Which of these factors influence the type and rate of weathering?A) mineral contentB) climateC) topographyD) all of theseAnswer: DDiff: 1

20) Sedimentary rocks ________.A) may contain fossilsB) hold important clues to Earth's historyC) may be economically importantD) all of the aboveAnswer: DDiff: 1

21) Detrital sedimentary rocks are classified (named) primarily on the basis of ________.A) colorB) type of beddingC) compositionD) particle sizeAnswer: DDiff: 1

22) Sedimentary rocks compose approximately ________ percent of Earth's outermost 10 miles.A) 5%B) 15%C) 30%D) 50%Answer: ADiff: 1

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23) Which rock type is associated with a high- energy environment (such as a very turbulent stream)?A) conglomerateB) shaleC) chertD) none of theseAnswer: ADiff: 1

24) Which pair of minerals is most common in detrital sedimentary rocks?A) quartz and olivineB) calcite and clayC) clay and quartzD) dolomite and gypsumAnswer: CDiff: 1

25) Detrital sediments would predominate in all of the following environments except ________.A) beachB) salt flatC) river floodplainD) deltaAnswer: BDiff: 1

26) Compaction would probably be most significant as a lithification process for ________.A) shaleB) sandstoneC) conglomerateD) brecciaAnswer: ADiff: 1

27) The most abundant chemical sedimentary rock is ________.A) limestoneB) dolomiteC) chertD) rock saltAnswer: ADiff: 1

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28) Which of the following best describes bedded gypsum and rock salt?A) detrital sedimentary rocksB) varieties of dolostoneC) varieties of coal and peatD) evaporites; chemical, sedimentary rocksAnswer: DDiff: 1

29) Coal beds originate in ________.A) shallow lakes in a dry, desert regionB) channels of fast-moving streamsC) deep, marine basins below wave actionD) freshwater coastal swamps and bogsAnswer: DDiff: 1

30) Metamorphism may result from ________.A) heatB) pressureC) chemical actionD) all of theseAnswer: DDiff: 1

31) ________ is a strong, parallel alignment of different mineral bands in a metamorphic rock.A) Rock cleavageB) FoliationC) Stress streakingD) MarbleizingAnswer: BDiff: 1

32) Which of the following changes may occur during metamorphism?A) Certain minerals may recrystallize.B) The rock becomes more compact.C) Crystals may grow larger.D) all of the aboveAnswer: DDiff: 1

33) The common rock produced by the metamorphism of limestone is ________.A) marbleB) mica schistC) phylliteD) gneissAnswer: ADiff: 1

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34) ________ is composed of alternating bands of light and dark silicate minerals.A) MarbleB) Mica schistC) PhylliteD) GneissAnswer: DDiff: 1

35) This dense, nonfoliated metamorphic rock is produced most often from sandstone.A) phylliteB) mica schistC) quartziteD) marbleAnswer: CDiff: 1

36) The agents of metamorphism are ________.A) uplifting and foldingB) foliation and depositionC) contact and regional deformationD) heat, pressure, and chemically-active fluidsAnswer: DDiff: 1

37) The primary agent of contact metamorphism is ________.A) foldingB) heatC) stressD) strainAnswer: BDiff: 1

38) What type of metamorphic rock will shale normally become following low-grade metamorphism?A) marbleB) mica schistC) slateD) gneissAnswer: CDiff: 1

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39) Which of the following lists the rocks in the order of increasing grain size and increasing grade of metamorphism?A) phyllite, slate, schistB) schist, slate, phylliteC) slate, phyllite, schistD) slate, schist, phylliteAnswer: CDiff: 1

Examine the words and/or phrases for each question below and determine the relationship among the majority of words/phrases. Choose the option which does not fit the pattern.

40) a. shale b. sandstone c. breccia d. conglomerateAnswer: aDiff: 2Type: Word Analysis Questions

41) a. lithification b. cementation c. weathering d. compactionAnswer: cDiff: 1Type: Word Analysis Questions

42) a. granite b. basalt c. diorite d. gabbroAnswer: bDiff: 1Type: Word Analysis Questions

43) Bowen's reaction series predicts the sizes of the different mineral grains that grow from crystallizing magmas.Answer: FALSEDiff: 1

44) Olivine and quartz are commonly found together in the same rock.Answer: FALSEDiff: 1

45) One magma can produce several different igneous rocks having different mineral compositions.Answer: TRUEDiff: 1

46) Basalt is the fine-grained equivalent of gabbro.Answer: TRUEDiff: 1

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47) Glassy igneous rocks form when magma cools too fast for mineral grains to grow.Answer: TRUEDiff: 1

48) Quartz is quite resistant to weathering and is an important component of sands in riverbeds and on beaches.Answer: TRUEDiff: 1

49) Like most other liquids, water decreases in volume when it freezes.Answer: FALSEDiff: 1

50) All atoms of the same element have the same atomic number.Answer: TRUEDiff: 1

51) The most abundant sedimentary rock is shale.Answer: TRUEDiff: 1

52) Evaporites have a biochemical origin.Answer: FALSEDiff: 1

53) Particle size is the primary basis for distinguishing among various detrital sedimentary rocks.Answer: TRUEDiff: 1

54) Most limestone has a biochemical origin.Answer: TRUEDiff: 1

55) Compaction is most significant as a lithification process for sedimentary rocks composed of sand-sized particles.Answer: FALSEDiff: 1

56) During metamorphism the material undergoing deformation remains essentially a solid.Answer: TRUEDiff: 1

57) The single most characteristic feature of sedimentary rocks are strata, or beds.Answer: TRUEDiff: 1

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58) The largest quantity of metamorphic rock is produced by regional metamorphism.Answer: TRUEDiff: 1

59) Slate is associated with high-grade metamorphism.Answer: FALSEDiff: 1

60) Metamorphism is commonly associated with mountain building.Answer: TRUEDiff: 1

61) Metamorphism can affect only sedimentary rocks.Answer: FALSEDiff: 1

62) ________ is the name given to molten rock below the Earth's surface.Answer: MagmaDiff: 1

63) ________ refers to the removal and isolation of early-formed mineral grains that can cause the composition of the remaining magma to change.Answer: Crystal settlingDiff: 1

64) Igneous rocks are classified on the basis of what two main characteristics?Answer: texture and mineral compositionDiff: 1

65) Obsidian exhibits a ________ texture.Answer: glassyDiff: 1

66) ________ weathering is accomplished by physical forces that break rock into smaller and smaller pieces without changing the rock's mineral composition.Answer: MechanicalDiff: 1

67) When water in cracks and joints freezes and expands the rock is broken into angular fragments. This process is known as ________.Answer: frost wedgingDiff: 1

68) ________ weathering alters the internal structures of minerals by removing and/or adding elements.Answer: ChemicalDiff: 1

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69) The two most common minerals in detrital sedimentary rocks are ________ and ________.Answer: clay; quartzDiff: 1

70) The most abundant chemical sedimentary rock is ________.Answer: limestoneDiff: 1

71) When a sedimentary rock consists of angular, gravel-sized particles, it is called ________.Answer: brecciaDiff: 1

72) Rock salt and rock gypsum are common examples of a group of chemical sedimentary rocks called ________.Answer: evaporitesDiff: 1

73) ________ refers to the processes by which unconsolidated sediments are transformed into solid sedimentary rocks.Answer: LithificationDiff: 1

74) Probably the single most characteristic feature of sedimentary rocks is ________.Answer: layering (strata or beds)Diff: 1

75) The partial decomposition of plant remains in an oxygen-poor swamp creates a layer of soft, brown material that is not yet coal. This material is known as ________.Answer: peatDiff: 1

76) List three agents of metamorphism.Answer: heat, pressure, chemically active fluidsDiff: 1

77) Metamorphism that occurs because of close proximity to a mass of magma is called ________ metamorphism.Answer: contactDiff: 1

78) When a metamorphic rock exhibits a layered or banded appearance, it is said to exhibit a ________ texture.Answer: foliatedDiff: 1

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Use complete sentences, correct spelling, and the information presented in Chapter 2 to answer the questions below.

79) Considering the various processes involved in mechanical and chemical weathering, what are some of the factors that influence or control the weathering of earth materials? Also, which of these factors would be most important?Answer: Higher temperatures speed chemical weathering. Carbon dioxide (the amount of CO2 in the water) lowers the pH, making the water more acidic. The amount of water in an environment is most important. The more wet an environment, a jungle for example, the more effective all chemical weathering processes. Diff: 2Type: Critical Thinking and Discussion Questions

80) How might a geologist infer ancient climatic conditions using sedimentary rocks? (Hint: Think in terms of the conditions necessary to form certain rocks and also the features, structures, and fossils found in sedimentary rocks.)Answer: The environment of deposition of the rock and the fossils within the rock give us the clue. If the rock is a dark claystone with fern fronds and dragonfly fossils within the layers, the sediments from which the rock is composed were likely deposited within a wet, warm environment. Diff: 3Type: Critical Thinking and Discussion Questions

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81) Fill in the missing rock names on the chart below.

Answer: See figure 2.8 in Foundations of Earth Science, 6e.Diff: 1Type: Visualization Questions

82) What type of stress (pressure) is illustrated in the diagram below?

Answer: Confining pressureDiff: 1Type: Visualization Questions

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83) What kind of sedimentary structure is pictured in the photograph below? (a) ___________________Explain how this kind of sedimentary structure forms. (b) ___________________

Answer: (a) mud cracks(b) Mud shrinks and cracks as it dries (as in an evaporating mud puddle).Diff: 2Type: Visualization Questions

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84) Carefully observe each of the photographs below of sedimentary rocks. To the right of each sample, name the rock and describe its origin (how it formed).

(a) ___________________

(b) ___________________

(c) ___________________

Answer: (a) conglomerateOrigin: A poorly sorted mixture of rounded grains of sand and gravel was lithified.(b) biochemical limestone or coquinaOrigin: A mass of calcareous seashells and broken shells was cemented together.(c) brecciaOrigin: A poorly sorted mixture of angular grains of sand and gravel was lithified.Diff: 2Type: Visualization Questions

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85) Examine the rock cycle (Figure 2.2 in the text). In nature, would it be possible for some of the steps to be "short-circuited" or interrupted, where instead of progressing directly from one step to the next, the circle might be crossed by a process? Give three examples where this might occur. For example, before a sedimentary rock becomes metamorphosed, could it be melted?Diff: 2

86) Can you explain why the ascending bodies of magma (like those illustrated in Figure 2.5 in the text) which feed a volcano or produce large intrusive bodies are shaped like inverted raindrops? Do you own a "lava lamp"? Might this observation help explain why large intrusive bodies are "rootless"?Diff: 3

87) The mantle of Earth is thought to be composed of peridotites. So why would new oceanic floor be basaltic composition when the source of the plate is the mantle? Hint, could ocean plate be an "evolved" rock type? If so, what process might change the peridotites to a basaltic composition?Diff: 3

88) Why do you think rhyolite is so uncommon at Earth's surface? After all, granite, rhyolite's slowly cooled equivalent, which formed at a depth of many kilometers is extremely common at the surface.Diff: 4

89) Can you pop a lifesaver into your mouth and let it dissolve to nothing over a period of five to ten minutes? Or after a few minutes do you happily crunch the candy into tiny bits? Why would a person be compelled to chew the candy up. What does this have to do with physical weathering of rocks?Diff: 2

90) Why do intrusive rocks chemically weather more quickly than extrusive rocks? Why do mafic rocks chemically weather more easily than felsic rocks? Hint, think of the constituent minerals of each rock type. So what rock type would you choose to face the new skyscraper you have designed?Diff: 3

91) From your text, page 58, Figure 2.18...."Vertical changes in rock types represent environmental changes through time." This statement certainly makes sense, as time passes, environments change on Earth's surface and the sediments deposited reflect those environments: ocean levels rise and fall; mountains are formed that are eventually reduced by weathering and erosion, and so on. But we also see horizontal changes in rock types (ancient sedimentary environments). Use the concept of uniformitarianism to explain this important concept.Diff: 4

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