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Geoscience > Test 2 > Flashcards

Test 2 Flashcards

1
Q

3 Major Rock Types and where they can be found on or in earth

A

Igneous: Can be found on and in Earth’s Surface
Sedimentary: Can be found on Earth.
Metamorphic: Can be found on and in Earth’s surface

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2
Q

Define bedrock and explain how its different from something like a large boulder.

A

Rock that is still attached to the Earth’s crust, its different from a boulder because a bolder can be detached from Earth’s crust.

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3
Q

Explain the difference between volcanic (extrusive) and intrusive igneous rocks, and prove an example of each.

A

A volcanic extrusive rock forms when magma rises to Earth’s surface. A volcanic intrusive rock forms when magma solidifies below Earth’s surface. Two examples of extrusive are andesite and basalt. Two examples of intrusive are diorite and gabbro.

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4
Q

Explain how the characteristics of an igneous rock (color and texture) provide information on its cooling history and silica content

A

The texture of the igneous rock helps you determine what size grains you have.
The darker the rock the lower the silica content, the lighter the rock the higher the silica content.

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5
Q

Characterize the igneous rock basalt and indicate where it would most likely be found. (extrusive/intrusive, oceanic crust/continental crust, divergent boundary/convergent boundary)

A

extrusive, oceanic crust, divergent boundary

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6
Q

Characterize the igneous rock rhyolite and where it most likely be found (extrusive/intrusive, oceanic crust/continental crust, divergent boundary/convergent boundary)

A

extrusive, continental crust, convergent boundary

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7
Q

Characterize the igneous rock granite and where it most likely be found (extrusive/intrusive, oceanic crust/continental crust, divergent boundary/convergent boundary)

A

intrusive, continental crust, convergent boundary

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8
Q

Characterize the igneous rock gabbro and where it most likely be found. (extrusive/intrusive, oceanic crust/continental crust, divergent boundary/convergent boundary)

A

Intrusive, oceanic crust, divergent

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9
Q

Explain the differences with respect to cooling history, silica content, and density between basalt and granite

A
  • Basalt cools at an average pace, has lower silica content, and is dense
  • Granite cools slowly, has a higher silica content and is less dense
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10
Q

Describe the 3 ways to melt a rock (3 ways to form magma)

A
  1. Increase temperature
  2. Decrease pressure
  3. Add volatiles (ex. water)
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11
Q

Explain why the temperature necessary to melt a rock increase with depth.

A

Temperature has to increase with depth because as depth increases the melting temperature rises

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12
Q

Explain how the source of a magma controls its initial composition

A
  • Mafic magma is formed by the partial melting of the mantle, low silica
  • Felsic magma is formed by the partial melting of the continental crust, silica rich
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13
Q

Explain the process of partial melting and how that controls the composition of a magma

A
  • Felsic minerals = lowest melting temps

- Mafic minerals = highest melting temps

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14
Q

What are the two main types of volcanoes

A
  • Stratovolcanoes

- Shield Volcanoes

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15
Q

What is the shape of a stratovolcano?

A

looks like a traditional volcano

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16
Q

What is the shape of a shield volcano?

A

looks like an upside down shield

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17
Q

Difference between stratovolcanoes and shield volcanoes

A
  • Stratovolcanoes are formed at subduction zones (convergent boundaries) hazards include: tephra, lahars and pyroclastic flows
  • Shield volcanoes are formed mostly at hotspots and sometimes at subduction zones. only hazards are lava flows and cinder cones
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18
Q

Viscosity

A

a lavas resistance to flow

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19
Q

What are the two factors that control the viscosity of a given magma?

A
  • Magma Composition

- Temperature

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20
Q

How does magma composition and temperature effect viscosity of a given magma?

A
  • Felsic/intermediate lava = high viscosity. The melt is at a lower temperature
  • Mafic = low viscosity. The melt is a higher temperature
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21
Q

How do magma composition, viscosity, gas content, and temperature relate to how explosive an eruption is?

A
  • High viscosity: lava piles up in lava domes (rhyolite). Gases trapped, lower temp and high silica (abundant silica chains). Leads to more explosive eruptions
  • Low viscosity: lava spreads out (Basalt) gases escapes easily, higher temp and lower silica (fewer silica chains) leads to more mild eruptions.
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22
Q

Where on a map of plate boundaries are you most likely to find high or low viscosity magma?

A
  • High: convergent

- Low: Hot spots

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23
Q

Where on a map of plate boundaries are you likely to find more and less explosive volcanoes?

A
  • More explosive: often found at convergent boundaries

- Less explosive: Divergent boundaries

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24
Q

Where on a map of plate boundaries are you most likely to find felsic and maifc magma?

A

Felsic: Convergent plate boundaries at edges of continental crust
Mafic: Divergent

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25
Q

What is a caldera

A

A collapsed volcano

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26
Q

How is a caldera formed

A

When a volcano collapses into itself which is triggered by the emptying of the magma chamber, as the result of a large volcanic eruption

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27
Q

How is pillow basalt formed

A

When lava of basaltic composition erupted under water the rapid cooling of the lava formed the igneous rock.

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28
Q

What are the difference in hazards associated with shield volcanoes and stratovolcanoes

A
  • Shield: Lava flows and cinder cones

- Stratovolcanoes: Tephra, lahars, pyroclastic flows

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29
Q

Define lahar

A

Volcanic mudflow

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30
Q

Define Pyroclastic flow

A

Hot gases and tephra travel in the air

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31
Q

What hazards were associated withthe eruption of Mount St. Helens

A

Lahar and pyroclastic flow

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32
Q

Explain why Hawaii and Yellowstone have such different types of volcanism (Hawaii = lava flows; Yellowstone = supervolcano with huge eruptions) if they are both caused by hot spots.

A

Hawaii is an oceanic hotspot while Yellowstone is a continental hotspot

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33
Q

List the 4 ways in which volcanic activity is monitored, and what changes indicate an impending eruption

A
  • Increased seismic activity
  • Increased gas activity
  • Changes in topography, shape
  • Changes in temperature
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34
Q

Explain how volcanic eruptions can impact climate

A

Formation of aerosols after eruption can create some global cooling

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35
Q

Define weathering and what are the two main types of weathering?

A
  • The processes that break up and corrode solid rock, eventually transforming it into sediment.
  • Physical & chemical
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36
Q

Provide examples of physical weathering

A

jointing, root, thermal expansion

37
Q

Provide examples of chemical weathering

A

Dissolution, hydrolysis, oxidation

38
Q

List and explain various factors that control the rate of weathering in a given area.

A
  • Fractures: faster with more & larger fractures
  • Temperature: faster with more freeze/thaw cycles
  • Precipitation: faster with more water for chemical reactions
  • Vegetation: faster with roots, burrows
  • Rock types: faster with weak rocks or rocks prone to chemical weathering
39
Q

Provide multiple examples of erosion on Earth’s surface

A
  • Wind
  • Rivers
  • Glaciers
  • Humans
40
Q

Explain the difference between clastic, chemical, and biochemical sedimentary rocks

A
  • Clastic: Formed by lithification
  • Chemical: Precipitated from a solution as a result of changing physical or chemical conditions
  • Biochemical: Living organisms cause minerals to be precipitated from solution. Remains of dead plants/organisms (coal, limestone, chalk)
41
Q

4 steps in the formation of a clastic sedimentary rock

A
  1. Breakdown of rock to form sediment
  2. Transportation of sediment
  3. Deposition of sediment
  4. Lithification
42
Q

Define lithification

A

the process of turning the sediment into a rock with heat and pressure

43
Q

What does the process of lithification include

A

Compaction and cementation

44
Q

How is limestone formed?

A

Formed from the accumulation of
shells, coral, other
marine life debris

45
Q

Difference between evaporites and travertine

A

The difference is that evaporites are a result of changing chemical conditions and travertine isa result of changing physical conditions.

46
Q

3 ways sediment is classified

A
  1. Size
  2. Angularity
  3. Sorting
47
Q

Explain how sediment changes as it moves from it source toward its place of final deposition.

A
  • There is a decrease in types of minerals
  • They are well sorted
  • They are rounded
48
Q

Depositional environment

A

Where the sediment or rock is deposited on earths surface

49
Q

Mountain stream: name the rock that would likely form if the sediment found there were lithified into rock

A

breccia and conglomerate

50
Q

Beach or sand dunes: name the rock that would likely form if the sediment found there were lithified into rock

A

sandstone

51
Q

River: name the rock that would likely form if the sediment found there were lithified into rock

A

rippled sandstone, siltstone, and shale

52
Q

Lake: name the rock that would likely form if the sediment found there were lithified into rock

A

shale

53
Q

Shallow marine environment: name the rock that would likely form if the sediment found there were lithified into rock

A

siltstone and mudstone containing marine fossils

54
Q

Shallow water carbonate environments: name the rock that would likely form if the sediment found there were lithified into rock

A

various kinds of limestone

55
Q

Deep marine deposits: name the rock that would likely form if the sediment found there were lithified into rock

A

mudstone, chalk, or bedded chert

56
Q

Identify the depositional environment of rock salt

A

large enclosed bodies or seawater and desert lakes

57
Q

Identify the depositional environment of travertine

A

hot springs

58
Q

Identify the depositional environment of coal

A

swamp

59
Q

Identify the depositional environment of chalk

A

Deep marine

60
Q

Identify the depositional environment of limestone

A

marine environments

61
Q

Explain how biochemical sedimentary rocks are formed, specifically chalk, limestone, and coal.

A

Formed by the accumulation of hells, coral, and other marine life debris

62
Q

How does limestone dissolution work?

A

Water absorbs carbon dioxide and the carbonic acid that comes into contact with the calcite in the limestone and then it dissolves.

63
Q

Why might a depositional environment change

A

Due to changing environment for example changing sea levels. Transgression and regression

64
Q

Define transgression

A

increase in sea level

65
Q

Define regression

A

decrease in sea level

66
Q

What does mud cracks indicate about their environment of formation?

A

Drying up of muddy sediment

67
Q

What does ripple marks indicate about their environment of formation?

A

Indicate flowing water

68
Q

What does cross beds indicate about their environment of formation?

A

There was a flowing medium, water or wind.

69
Q

Difference between the brittle and ductile zone

A
  • Brittle zone: stress causes rock to fracture

- Ductile Zone: Increasing Stress and temperature causes rock to flow in solid state

70
Q

Roughly what depth is the brittle ductile transition zone

A

~15 km

71
Q

Explain what metamorphism is

A

Changes in mineral composition and the texture that can occur in any solid rock due to pressure, temperature, and presence of fluids. Happens in the ductile zone.

72
Q

How do rocks respond to metamorphism?

A
  • Rocks can grow new minerals (recrystallize) in the ductile zone
  • Deformation (faults, folds)
  • They can foliate
73
Q

Identify the range of temperatures in which metamorphism is likely to occur

A

Low end: 300-600C

High end: 700C and up

74
Q

Contact metamorphism

A

Occurs due to increasing temperature near magma

75
Q

Regional metamorphism

A

Occurs due to increasing temperature and pressure along plate boundaries.

76
Q

Examples of foliated metamorphic rocks

A

Slate, schist, gneiss

77
Q

Examples of non foliated metamorphic rocks

A

hornfels, marble, quartzite

78
Q

How is foliation formed in a metamorphic rock?

A

The application of pressure

79
Q

Explains how marble forms

A

When limestone is exposed to high temperatures and pressures

80
Q

Where is contact metamorphism likely to occur

A

Convergent and divergent boundaries

81
Q

Where is regional metamorphism likely to occur?

A

Convergent boundary

82
Q

Examples of low grade metamorphic rocks

A

Shale and slate

83
Q

Example of medium grade metamorphic rock

A

Schist

84
Q

Examples of high grade metamorphic rocks

A

Gneiss and migmatite

85
Q

List and explain the steps of the rock cycle

A
  1. Weathering of all rock types on the surface
  2. Transportation/erosion of rocks particles by rain, wind, streams etc.
  3. Deposition
  4. Compaction and Cementation creating sedimentary rocks
  5. Metamorphism sedimentary or igneous rocks turn in to metamorphic rocks
  6. Rock melting: metamorphic rocks melt underground and when an eruption occurs the lava cools on the surface and becomes igneous rock
86
Q

Lithification takes place at what temperature to form sedimentary rocks?

A

Below 200oC

87
Q

Metamorphism takes place at what temp to form metamorphic rocks:

A

200-1000oC

88
Q

Melting takes place at what temp to form magma?

A

1100oC and above

Geoscience (4 decks)

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