GEOLOGY 303 Lab Midterm

FALL 1996

Version B

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Lab Section:

PART I (40 points)

MINERALS (8 points)

1. Identify this mineral. A) quartz B) calcite C) earthy hematite D) olivine E) halite

2. This mineral displays what kind of luster? A) vitreous B) pearly C) metallic D) resinous E) glassy

3. Identify this mineral. A) orthoclase feldspar B) kaolinite C) talc D) biotite mica E) gypsum

4. Identify this mineral. A) plagioclase feldspar B) hornblende C) orthoclase feldspar D) calcite E) quartz

5. Describe the cleavage of this mineral fully. A) rhombohedral B) cubic cleavage C) 1 direction of cleavage D) 2 directions of cleavage that intersect at 90( E) this mineral does not display cleavage

6. Identify this mineral. A) halite B) magnetite C) earthy hematite D) pyrite E) graphite

7. Identify this mineral. A) calcite B) garnet C) olivine D) augite E) quartz

8. Identify this mineral. A) pyrite B) galena C) magnetite D) basalt E) garnet

IGNEOUS ROCKS (8 points)

9. If the magma that formed this rock cooled at a much faster rate, what igneous rock would it form? A) basalt B) gabbro C) granite pegmatite D) rhyolite E) scoria

10. Identify this igneous rock. A) gabbro B) peridotite C) obsidian D) pumice E) andesite porphyry

11. This rock... A) is rich in felsic minerals B) contains abundant quartz, biotite, and orthoclase feldspar C) contains abundant augite and olivine D) contains abundant hornblende, plagioclase feldspar, and augite E) is an ultramafic rock

12. Identify this igneous rock. A) obsidian B) basalt C) rhyolite D) pumice E) scoria

13. The “holes” in this igneous rock are formed by... A) the presence of trapped gases as the lava cooled at the Earth’s surface B) the presence of volatiles as the magma completely crystallized deep within the Earth C) the presence of the burrowing organism Palaeoasylpina D) dissolution of unstable calcite (forming molds) E) effervescence in dilute Hydrochloric Acid

14. Identify this igneous rock. A) rhyolite B) andesite porphyry C) basalt D) gabbro E) peridotite

15. Identify this igneous rock. A) obsidian B) rhyolite (or rhyolite porphyry) C) andesite porphyry D) granite E) siltstone

16. Identify this igneous rock. A) granite B) basalt C) granite pegmatite D) peridotite E) obsidian

METAMORPHIC ROCKS (8 points)

17. Identify this metamorphic rock. A) peridotite B) serpentinite C) gneiss D) amphibolite E) slate

18. Identify this metamorphic rock. A) marble B) quartzite C) schist D) phyllite E) gneiss 19. What is a possible parent rock for this metamorphic rock? A) limestone B) arkose C) granite D) peridotite E) quartz-cemented, quartz sandstone

20. Identify this metamorphic rock. A) schist B) slate C) gneiss D) phyllite E) shale

21. Identify this metamorphic rock. A) marble B) amphibolite C) gneiss D) quartzite E) serpentinite

22. The dark minerals in this metamorphic rock are... A) biotite mica B) muscovite mica C) hornblende D) smoky quartz E) staurolite

23. Identify this metamorphic rock. A) schist B) slate C) phyllite D) quartzite E) amphibolite

24. Identify this metamorphic rock. A) schist B) quartzite C) granite D) slate E) gneiss SEDIMENTARY ROCKS (8 points)

25. Identify this sedimentary rock. A) siltstone B) arkose C) quartz sandstone D) fossiliferous limestone E) rock salt

26. This sedimentary rock displays what sedimentary structure? A) mud cracks B) burrows C) stratification D) cross bedding E) ripples

27. Identify this sedimentary rock. A) limestone B) conglomerate C) rock salt D) rock gypsum E) dolomite

28. Describe the roundness and sorting displayed in this rock. A) well rounded grains, well sorted B) well rounded grains, poorly sorted C) angular grains, well sorted D) angular grains, poorly sorted E) these terms don’t apply to chemical sedimentary rocks such as this one

29. Identify this sedimentary rock. A) limestone B) chert C) rock salt D) shale E) quartz sandstone

30. Identify this sedimentary rock. A) rock salt B) dolomite C) chert D) limestone E) coquina 31. Identify this sedimentary rock. A) rock salt B) quartz sandstone C) siltstone D) shale E) rock gypsum

32. Identify this sedimentary rock. A) siltstone B) chert C) slate D) shale E) arkose

FOSSILS (8 points)

33. Identify this fossil. A) bivalve B) echinoid C) algal fruiting body D) shark tooth E) gastropod

34. Identify this fossil. A) bivalve B) ammonite C) brachiopod D) coral E) sponge

35. Identify this fossil. A) coral B) sponge C) algal fruiting body D) ammonite E) gastropod

36. Identify this fossil. A) sponge B) bivalve C) ammonite D) fusulinid E) brachiopod 37. This body fossil is preserved with what form of alteration? A) replacement B) compression C) permineralization D) mold E) cast

38. Identify this fossil. A) gastropod B) algal fruiting body C) shark tooth D) sponge E) fusulinid

39. Identify this fossil. A) ammonite B) gastropod C) brachiopod D) bivalve E) coral

40. This fossil displays what kind of symmetry? A) pentagonal B) bilateral across the valves C) bilateral between the valves D) radial E) this fossil does not display any symmetry PART II (60 points)

MINERALS (12 points)

41. Garnet typically has... A) well developed cubic cleavage B) metallic luster C) well formed crystal faces in the form of dodecahedral crystals D) the same hardness as calcite

42. Which of the following choices is a ferromagnesian mineral (a mineral containing iron and magnesium)? A) shale B) galena C) olivine D) quartz E) muscovite

43. Which of the following criteria is NOT used to define a substance as a mineral? A) inorganic B) crystalline C) naturally occurring D) definite chemical makeup E) at least one direction of cleavage

44. The process by which rocks are transformed into other rock types (and relates all rock types to one another) is: A) the rock cycle B) Bowen’s reaction series C) The Linnean process D) permineralization E) orthogonal hexagony and the differentiation of mantle segregates

45. All of the following statements about orthoclase feldspar and plagioclase feldspar are FALSE except for which? A) orthoclase has 2 directions of cleavage that meet at 90( and plagioclase has 2 directions of cleavage that intersect at 124( and 56(. B) they both have an identical chemical makeup C) one has a wavy internal pattern and the other has record groove striations D) orthoclase is always light pink and plagioclase is always white 46. Which of the following are common properties of mica minerals? A) one direction of cleavage B) occur as “books” or scattered flakes C) vitreous luster D) very low hardness E) all of the above

47. Which of the following is/are properties belonging to calcite? A) effervesces in dilute hydrochloric acid B) displays well developed cubic cleavage C) displays rhombohedral cleavage D) A and B both E) A and C both

48. Which of the following INCORRECTLY finishes the statement: “The streak of a particular mineral... “ A) is unique that that mineral alone B) does not have to be the same color as the mineral itself C) can only be obtained for minerals softer than your streak plate D) can be a good identifying property of a mineral in some cases

49. Olivine displays all but one of the following features. Choose the FALSE one. A) conchoidal fracture B) distinct green color C) sugary texture of crystal masses D) can be scratched easily with a penny

50. Well developed crystal faces develop as a mineral grows unobstructed (freely), and the form is determined by... A) internal atomic arrangement B) cleavage planes C) hardness of the mineral D) tenacity

51. Which of the following materials is a mineral? A) obsidian B) glacial ice C) synthetic rubies D) siliceous magma E) none of the above 52. What is the best way to distinguish between quartz and gypsum? A) color B) hardness C) luster D) transparency E) one effervesces in dilute hydrochloric acid

IGNEOUS ROCKS (12 points)

53. Which of the following are geologic reasons for granite being found at the Earth’s surface: A) it crystallized at the Earth’s surface B) it formed deep within the Earth and subsequent erosion occurred C) it is an intrusive rock that was uplifted to the surface by tectonic activity D) both A and B E) both B and C

54. Imagine you are given an igneous rock sample. Which of the following lists of interpretations and descriptive terms are consistent (plausible) for an igneous rock sample: A) formed from magma, plutonic, intrusive, indicates rapid cooling B) formed from lava, extrusive, fine grained, indicates rapid cooling C) formed from magma, volcanic, intrusive, indicates slow cooling D) formed from lava, volcanic, extrusive, coarse grained E) formed from lava, intrusive, plutonic, indicates rapid cooling

55. You find a sample of gabbro. What would be its general mineral composition? A) quartz, orthoclase feldspar, and biotite B) quartz, calcite, halite C) mostly olivine with some augite (pyroxene) D) augite, plagioclase feldspar, hornblende E) it is not composed of minerals

56. Pick the correct completion of the statement: “A composite volcano...” A) is broad and gently sloping B) is completely mafic in composition, and has steeply dipping sides due purely to erosional processes C) is mostly felsic in composition, and has steeply sloping sides D) none of the above

57. Which statement about shield volcanoes is FALSE? A) they are broad and gently sloping B) they are composed of large amounts of pyroclastic debris C) they occur most frequently on oceanic plates D) they have relatively quiet eruptions E) they are mafic in composition 58. Generally, from top to bottom on Bowen’s Reaction Series, which of the following statements is FALSE? A) It shows the crystallization order of minerals as magma cools. B) It is easier to melt minerals. C) Minerals are more resistant to chemical weathering. D) The viscosity of the magma increases. E) All the above statements are true.

59. All of the following are differences between felsic and mafic magmas (or rocks) EXCEPT which? A) Mafic lavas are less viscous than felsic lavas. B) Mafic rocks always cool deep in the earth, and felsic ones always cool at shallow depths. C) Mafic rocks are darker and denser than felsic rocks. D) Mafic magmas contain fewer volatiles than felsic magmas. E) Mafic rocks are the primary constituent of oceanic crust, and felsic rocks are the primary constituent of continental crust.

For questions 60-62, match the texture with the cooling history:

60. Porphyry A) Slow cooling B) Extremely rapid cooling 61. Glass C) Rapid cooling D) A long period of slow cooling followed 62. Pegmatite by a period of rapid cooling

63. Igneous rocks with felsic compositions are characterized by: A) minerals rich in iron and magnesium B) quartz, biotite, and olivine C) light colored minerals such as orthoclase feldspar, plagioclase feldspar, and quartz D) none of the above

64. Columnar jointing is defined as polygonal columns in basalt which form when: A) it cools and expands B) ancient cultures carved them into the columns for building stones C) it heats up and expands D) it cools and shrinks METAMORPHIC ROCKS (12 points)

65. Which of the following properties or statements about regional metamorphism is FALSE? A) involves high temperatures B) involves deformation and shear stress C) metamorphic rocks thus formed show no development of foliation D) involves high pressures E) causes changes in the parent rock’s mineralogy and / or texture

66. In the transformation from slate to schist, which statement best describes what process is occurring? A) discontinuous light and dark layering in a schist is due to mineral segregation caused by shear stress (directed pressure) B) contact metamorphism obliterates any pre-existing foliation C) parallel aligned microscopic mica grains become larger D) micas are eroded, transported, and redeposited in layers E) none of the above

67. After metamorphism, calcite in marble will... A) have cubic cleavage B) be harder than quartz C) still react with hydrochloric acid D) no longer be crystalline

68. If you had a metamorphic rock containing garnet and staurolite crystals, which other mineral(s) would you expect to see? A) chlorite B) mica C) kyanite or sillimanite D) both A and B E) none of the above

69. Which one of the following pairs of metamorphic rocks and associated parent rocks is INCORRECT? A) marble:dolomite B) gneiss:arkose C) schist:shale D) amphibolite:chert E) all of the above pairs is correct 70. Which of the following are NOT factors which aid in metamorphism: A) high temperature B) high pressure C) the presence of fluids D) shear stress E) erosion

71. Which of the following statements about contact metamorphism is FALSE? A) achieved chiefly by the application of heat to a rock B) occurs as a result of heat and fluids escaping from cooling magma C) foliated rocks can be formed in this manner D) occurs in a small isolated area surrounding a cooling batholith

72. Which of the following changes CANNOT occur with increasing metamorphic grade? A) development of foliation B) radical alteration of the bulk chemical composition of the parent rock C) change in the mineral composition D) mineral deformation

73. Which of the following rocks could not be a parent rock for Gneiss? A) Granite B) Schist C) Basalt D) A quartz-cemented, quartz sandstone E) Shale

74. Which of the following list of rocks is correctly ordered by increasing metamorphic grade? A) slate, shale, phyllite schist, chert B) shale, slate, phyllite, schist, chert C) amphibolite, slate, schist, phyllite, chert D) shale, slate, phyllite, amphibolite, gneiss E) none of the above

75. Schistosity develops in some medium-grade metamorphic rocks because of... A) pre-existing sedimentary layering in the parent rock B) segregation of different minerals into layers C) the parallel alignment of coarse-grained, platy (or elongate) minerals D) diagenetic degradation of the phenocrysts which removes mica from the rock E) none of the above 76. Which of the following occurrences is IMPOSSIBLE during metamorphism? A) partial melting of mafic minerals B) removal of some water C) drastic changes in the mineral composition of the rock D) formation of foliation or layering E) changes in the shape or size of the mineral grains

SEDIMENTARY ROCKS (12 points)

For questions 77-80, match the sedimentary rock to the depositional environment (A-E)

77. Conglomerate A) Landslide B) Mountain stream bed 78. Fossiliferous Limestone rich in coral C) Cold, deep marine D) Warm, shallow marine 79. Rock Salt E) Shallow, intermittent lake in desert

80. Breccia

81. Put the following clastic rocks in order of increasing grain size: siltstone, shale, conglomerate, sandstone A) siltstone, shale, conglomerate, sandstone B) shale, siltstone, sandstone, conglomerate C) shale, sandstone, siltstone, conglomerate D) conglomerate, sandstone, siltstone, shale

82. Sea water is COMPLETELY evaporated from a marine basin. Three minerals one would expect to be precipitated from this process would be: A) calcite, gypsum, halite B) conglomerate, gypsum, and halite C) halite, garnet, orthoclase feldspar D) gypsum, halite, olivine E) none of the above

83. The best argument for why COQUINA can be considered a clastic sedimentary rock is... A) the clasts were deposited by organisms B) the clasts are larger than 2 mm in diameter C) the clasts show a short history of transportation D) the clasts are transported, deposited, and cemented E) it fizzes when dilute Hydrochloric acid is applied 84. The most common types of cement in a sedimentary rock include: A) carbon, ash, calcium carbonate (calcite) B) sand, silt, clay C) calcium carbonate (calcite), silica (quartz), iron oxide (hematite) D) calcium carbonate (calcite), sand, clay E) potassium feldspar, silica (quartz), biotite mica

85. ... consist(s) of internal layers that are inclined with respect to the bed as a whole. A) Ripple marks B) Cross bedding C) Mud cracks D) Vesicles E) Foliation

86. ... is the low temperature, low pressure process which transforms loose, unconsolidated sediment into sedimentary rock. A) Volatilization B) Weathering C) Transportation D) Fossilization E) Diagenesis

87. Which of the following minerals has the highest resistance to chemical weathering at the Earth’s surface? A) quartz B) olivine C) biotite D) orthoclase feldspar E) muscovite

88. Which of the following is/are characteristics of a clastic sedimentary rock which has been transported a great distance? A) well rounded grains B) well sorted grains C) quartz-rich D) only A and B E) A, B, and C FOSSILS (12 points)

89. Evidence of past life that does not include a part of the organism, but rather only signs of an organism’s activity is called a... A) trace fossil B) phylum C) cast D) mold E) body fossil ] 90. The estimated age of the Earth is: A) 3 million years B) 3.5 billion years C) 400 million years D) 4.5 billion years E) 10 billion years

91. ... is the fundamental principle of geology which states that in a sequence of undeformed sedimentary rocks, the oldest rocks are buried the deepest. A) Original horizontality B) Cross-cutting relationships C) Superposition D) Faunal succession E) Preservation

92. The geologic Period which immediately precedes the Silurian is the... A) Cambrian B) Devonian C) Triassic D) Tertiary E) Ordovician

For questions 93-96, match the following organisms with the correct body plan (A-E)

93. Gastropods A) Radial B) Bilateral between the valves 94. Brachiopods C) Pentagonal D) Bilateral across the valves 95. Bivalves E) Coiled

96. Echinoids 97. The best environment for fossil preservation is one where... A) warm, shallow marine water is present B) high-energy and fine-grained sediments are prevalent C) low-energy and slow burial are dominant D) low energy, fine-grained sediment, and rapid burial are present E) the organisms were transported for long distances before being deposited

98. Index fossils are... A) abundant, geographically wide-ranging, readily preserved, and rapidly evolved B) slowly evolved, abundant, and soft bodied C) found only in a very specific geographic area D) scarce, readily preserved, and large E) all vertebrates

99. The natural bias which results from the fact that some organisms (or parts thereof) are more readily fossilized than others is termed... A) Collector’s Bias B) Fossil Bias C) Preservation Bias D) The Fossil Conspiracy E) Uniformitarianism

100. Using the chart, determine the time (age) range for the deposition of a rock which contains the organisms represented by stars, triangles, and squares. A) Mississippian through Permian B) Middle Mississippian through Middle Permian C) Middle Permian through Late Jurassic D) Late Pennsylvanian through Middle Permian E) Middle Ordovician through Early Mississippian