Geology 101 Quiz 4 Flashcards

1
Q

knowledge of rock properties can help determine things like

A

where it is dangerous to build, whether a groundwater contaminant will migrate off site, what is the best material for making buildings or highways

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2
Q

understanding earth processes can help determine things like

A

where to expect earthquakes, where to dig for gold or oil, how to make synthetic rubies and diamonds, why a lake in Africa discharged a CO2 cloud that killed hundreds

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3
Q

three basic rock types

A

igneous, sedimentary, metamorphic

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4
Q

igneous rocks

A

formed by solidification from magma

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5
Q

sedimentary rocks

A

formed by accumulation and lithification of existing mineral grains OR precipitation of dissolved ions from water

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6
Q

metamorphic rocks

A

formed by alteration of existing rocks under high temperature and/or pressure

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7
Q

lithification

A

the process of turning sediments into rock

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8
Q

weathering

A

physical breakage and chemical decomposition of rocks (including dissolution)

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9
Q

erosion

A

transport of weathered rock away from point of origin

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10
Q

rock cycle

A

rocks are generally thought of as eternal; rocks can be “recycled,” where one rock can be broken down or altered and turned into a different type of rock

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11
Q

igneous rock -?-> weather erode

A

uplift

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12
Q

weather erode -?-> sedimentary

A

deposition, burial, lithification

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13
Q

sedimentary -?-> weather erode

A

uplift

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14
Q

sedimentary -?-> metamorphic

A

heat pressure

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15
Q

metamorphic -?-> weather erode

A

uplift

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16
Q

metamorphic -?-> igneous

A

melt, cool, solidify

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17
Q

igneous -?-> metamorphic

A

heat, pressure

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18
Q

sedimentary cannot go straight to ? and why

A

igneous; a sedimentary rock will form a metamorphic rock prior to melting

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19
Q

?, or texture of an igneous rock, was used to classify igneous rocks before it was really understood why it varied so much

A

crystal size

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20
Q

the primary clues to what causes crystal size to vary in igneous rocks came from studying ?

A

volcanic lava flows (since the flows started as magma and solidified to form igneous rocks)

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21
Q

if a section of cooled lava was broken open, several observations could be made:

A

large crystals are never observed in lava; of the small crystals present, the larger crystals are always found near the base or middle, never at the top

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22
Q

what suggested that time must play a role in igneous rock crystal size?

A

the top of the lava flow cools the fastest and the interior cools slowly

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23
Q

igneous rocks: the slower the cooling rate, the more time atoms have to ?

A

align themselves to grow larger crystals

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24
Q

since lava flows always produce small crystals, igneous rocks with large crystals must have formed where?

A

beneath the surface where cooling rates could be very slow

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25
Q

the presence of ? in magma also facilitates larger crystal growth

A

water

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26
Q

two categories of igneous rocks

A

intrusive, extrusive

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27
Q

intrusive igneous rock

A

magma intruded into existing rock and solidified beneath the surface

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28
Q

extrusive igneous rock

A

magma extruded to the surface (lava) and solidified on the ground

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29
Q

igneous rocks are classified using two different systems based on either ? or ?

A

the occurrence of the rock (where found and in what form) or the composition of the rock (what minerals it is made from)

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30
Q

pluton

A

large igneous body formed at depth

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31
Q

batholith

A

large pluton

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32
Q

stock

A

smaller pluton

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33
Q

plutons form in different ways, but all ways start with

A

magma that begins to rise (because it is less dense than solid rock)

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34
Q

the simplest way a pluton forms is by simply

A

melting its way upward

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35
Q

a pluton may also form by stressing ?

A

overlying rock and flowing upward into fractures

36
Q

sill

A

tabular intrusion between existing layers

37
Q

sills usually form (horizontally/vertically) because most layers are (horizontal/vertical)

A

horizontally; horizontal

38
Q

dike

A

roughly planer intrusion that cuts across existing layers

39
Q

sills are also known as

A

concordant intrusives

40
Q

dikes are also known as

A

discordant intrusives

41
Q

vein

A

deposit of foreign minerals within a fracture; can be igneous or sedimentary

42
Q

if minerals precipitate out in a fracture from water heated by a magma body, the vein is considered ?

A

igneous

43
Q

if minerals precipitate out in a fracture at lower temperatures not associated with magma, the vein is considered ?

A

sedimentary

44
Q

examples of massive, uplifted batholiths

A

Yosemite National Park, California and The Sierra Nevada Mountains in California

45
Q

examples of a stock, possibly beneath an ancient volcano

A

Devil’s Tower, Wyoming and Ship Rock, New Mexico

46
Q

how can we tell if the vein or dike was there first?

A

if the veins cut through the dike, the dike was there first

47
Q

extrusive igneous rocks are divided into two categories

A

lava and pyroclastic material (tephra)

48
Q

lava

A

magma that flows over the surface of the ground and solidifies

49
Q

pyroclastic material (aka tephra)

A

magma and solidified fragments thrown into the air during an explosive eruption

50
Q

if magma intruded between two existing layers, the upper layer should show

A

some signs of alteration (metamorphism)

51
Q

if the crystals in the igneous rock are small and there is no metamorphism,

A

ancient lava flow

52
Q

if the crystals in the igneous rock are large and there is metamorphism,

A

it must be a sill

53
Q

8 minerals divided into 2 groups

A

felsic and mafic

54
Q

felsic minerals

A

high silica content (SiO2), which makes them less dense, and often lighter in color

55
Q

mafic minerals

A

low in silica, higher in Fe & Mg, which makes them more dense, and often darker in color

56
Q

mafic minerals are more abundant in (continental/oceanic) crust

A

oceanic

57
Q

mafic minerals (list)

A

olivine, pyroxene, amphibole, Ca-rich plagioclase

58
Q

felsic minerals (list)

A

quartz, muscovite, potassium feldspar, biotite, amphibole

59
Q

? is both mafic and felsic

A

amphibole

60
Q

granite is (intrusive/extrusive)

A

intrusive

61
Q

rhyolite is (intrusive/extrusive)

A

extrusive

62
Q

diorite is (intrusive/extrusive)

A

intrusive

63
Q

andesite is (intrusive/extrusive)

A

extrusive

64
Q

gabbro is (intrusive/extrusive)

A

intrusive

65
Q

basalt is (intrusive/extrusive)

A

extrusive

66
Q

peridotite is (intrusive/extrusive)

A

intrusive

67
Q

komatiite is (intrusive/extrusive)

A

extrusive

68
Q

granite and rhyolite are

A

felsic

69
Q

diorite and andesite are

A

intermediate

70
Q

gabbro and basalt are

A

mafic

71
Q

peridotite and komatiite are

A

ultra-mafic

72
Q

Magma rising through oceanic crust will tend to be made of ?

A

mafic minerals

73
Q

Magma rising through continental crust will tend to be ? if not much continental crust is melted

A

mixed

74
Q

Magma that melts lots of continental crust will tend to be ?

A

felsic

75
Q

volcanic glass

A

extrusive igneous rocks; occur when magma cools very fast and the resulting rock has no crystals

76
Q

obsidian

A

volcanic glass with no air bubbles

77
Q

pumice

A

volcanic glass with lots of air bubbles, called vesicles

78
Q

tuff

A

pyroclastic material fused into a solid rock

79
Q

volcanic ash

A

dust size tephra

80
Q

porphyry

A

a rock with large crystals (called phenocrysts) in a matrix of fine grained crystals

81
Q

mafic minerals generally melt at (lower/higher) temperatures than felsic minterals

A

higher

82
Q

at higher pressure, (lower/higher) temperatures are needed to melt the rock

A

higher

83
Q

if water is present, the rock will melt at a (lower/higher) temperature

A

lower

84
Q

Bowen’s Reaction Series refers to

A

the sequence of minerals that crystallize from a magma as it cools, and reactions that take place along the way

85
Q

discontinuous reaction series

A

the stepwise reaction sequence pathway (olivine to biotite)

86
Q

continuous reaction series

A

the gradual transition from Ca to Na rich plagioclase