Plate tectonics Flashcards

1
Q

who came up with the continental drift theory

A

Alfred Wegener

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2
Q

Continental Drift Theory

A

that the continents used to form one supercontinent but began to drift a part into their current positions

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3
Q

when was continental drift widely accepted

A

1950

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4
Q

why was the theory of continental drift NOT taken seriously at first

A

because there was no mechanism that could be explained

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5
Q

what were the two large portions that made up Pangaea

A
  1. Laurasia
  2. Gondwanaland
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6
Q

what happened to the continents 135 MYA

A

separated to more present shape WITHOUT separating too much

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7
Q

what did the continents look like 65 MYA

A

began to break apart from each other to be located in the present day locations

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8
Q

polar position

A

focused on the latitudinal position as a cause of the glaciation of continents = ice sheets should appear on continents when they are located at polar or near-polar latitudes.

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9
Q

describe polar position of the continents 440 MYA

A

polar position - yes
ice sheets - yes

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10
Q

describe polar position of the continents 390 MYA

A

polar position - yes
ice sheets - no

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11
Q

describe polar position of the continents 300 MYA

A

polar position - yes
ice sheets - yes

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12
Q

describe polar position of the continents 260 MYA

A

polar position - yes
ice sheets - yes

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13
Q

do the location of continents and whether they are together or separate affect weather

A

YES

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14
Q

where is slow flow

A

in the upper mantle

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15
Q

what drives slow flow and continent movements

A

convection cells

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16
Q

steps within the convection cells

A
  1. heating of the material in the mantle
  2. the hot material rises
  3. begins to move outwards
  4. cools
  5. eventually there will be collisions and subduction
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17
Q

how does the gravity push/pull affect plate tectonics

A

lava is pushed up while the weight of thickening plate is pushed down

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18
Q

curst formation steps

A
  1. material from the asthenosphere upwells along the sea floor and becomes extrusive igneous rock
  2. the oceanic crust is subducted under the lighter continental crust
  3. the subducted oceanic crust begins to melt
  4. melting generates magma = forms igneous intrusion rock and extrusive explosions
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19
Q

what is the range of speed for the movement of continents

A

from 1 to 12cm per year

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20
Q

how can the movement of continents differ

A
  1. in their speed
  2. in their direction
  3. in their orientation
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21
Q

what is the Wilson cycle focused on

A

the different formations of supercontinents in the past

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22
Q

how many supercontinents were expected to have been formed in 3 billion years (Wilsons cycle)

A

5

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23
Q

supercontinents act as

A

insulators - their mass traps geothermal heat in earth

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24
Q

what are the 4 steps in the Wilson cycle

A
  1. assembly
  2. stability
  3. splitting
  4. reassembly
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25
Q

average Wilson cycle takes ____ years

A

500 Million

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26
Q

does assembly in the Wilsons cycle have to be complete

A

NO- it can be incomplete

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27
Q

3 main types of plate boundaries

A
  1. convergent
  2. divergent
  3. transform
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28
Q

divergent plate boundary

A

plates move AWAY from each other

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29
Q

convergent plate boundary

A

plates move TOWARDS each other

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30
Q

transform plate boundary

A

plates move in OPPOSITE directions but they REMAIN together

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31
Q

types of convergent plates

A
  1. convergent oceanic plates
  2. convergent continental plates
  3. convergent oceanic AND continental plates
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32
Q

convergent plates results in _____

A

subduction

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33
Q

convergent OCEANIC plates results in

A

volcanic expression

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34
Q

convergent CONTINENTAL plates results in

A

formation of mountains (such as the Himalayas)

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35
Q

convergent of OCEANIC AND CONTINENTAL plates results in

A

volcanic activity

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36
Q

divergent CONTINENTAL plates results in

A

rift valleys and sometimes divots

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37
Q

TRANSFORM plates can be identified by

A
  1. ridges not lining up
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38
Q

3 main STRESS types of crust deformation

A
  1. tension
  2. compression
  3. shear
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39
Q

crust deformation
tension AKA

A

stretching

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40
Q

crust deformation
compression AKA

A

shortening

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41
Q

crust deformation
shear AKA

A

twisting

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42
Q

the stress of curst deformation results in

A

STRAIN

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43
Q

two examples of strains caused by crust deformation stress

A
  1. folding (bending)
  2. faulting (breaking)
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44
Q

what causes folding

A

compression at convergent plates

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45
Q

what are examples of the result of folding

A

basins and domes

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46
Q

anticlines and synclines in folding

A

the up and down folds that usually occur together and are caused by compressional stress

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47
Q

anticlines vs synclines of folding

A

Anticlines
folds in which each half of the fold dips away from the crest.

Synclines
folds in which each half of the fold dips toward the trough of the fold.

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48
Q
A

shear stress

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49
Q

shear stress results in

A

fault and bending horizontally

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50
Q
A

compression

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51
Q

compression results in ____ surface expression(s)

A
  1. folding
  2. faulting
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52
Q
A

tension

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53
Q

tension results in _____ surface expression

A

thining crust

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54
Q

what causes faulting

A

forces on both sides of a plate that causes fracture of material (break)

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55
Q

what are three examples of faulting

A
  1. normal fault
  2. thrust fault
  3. strike-slip fault
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56
Q

what causes a normal fault

A

tension

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57
Q

how do identify a normal fault

A

when the hanging-wall side is displaced DOWNWARDS

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58
Q

what causes a thrust fault

A

compression

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59
Q

how to identify a thrust fault

A

the hanging-wall side moves UPWARD

60
Q

what causes a strike-slip fault

A

shearing (twisting)

61
Q

how to identify a strike-slip fault

A

have offset on the surface (ex. ridge lines DON’T line up)

62
Q

is there vertical displacement in a strike-slip fault

A

NO

63
Q

what fault is caused by diverging forces

A

normal fault

64
Q

what fault is caused by converging forces

A

reverse/thrust fault

65
Q

what fault is this

A

reverse/thrust fault

66
Q

what fault is this

A

normal fault

67
Q

what fault is this

A

strike-slip fault

68
Q

orogenesis

A

mountain generation

69
Q

examples of orogenesis

A
  1. folding and faulting
  2. plate collisions
  3. addition of terranes
  4. volcanic addition
  5. uplift
70
Q

what are some examples of plate interactions that cause orogenesis

A
  1. continent to continent
  2. ocean to continent
  3. ocean to ocean
71
Q

three mountain ranges formed by orogenesis

A
  1. rocky mountains
  2. Appalachians
  3. Himalayas
72
Q

what mountain range is this

A

Rocky Mountains

73
Q

what mountain range is this

A

Appalachians

74
Q

what mountain range is this

A

Himalayas

75
Q

earthquakes are a

A

series of shocks caused by movement in the crust OR upper mantle

76
Q

where do earthquakes often happen

A

along fault lines

77
Q

center of earthquake movement

A

focus

78
Q

where is the point of failure when referring to earthquakes

A

the focus

79
Q

what is the point on the surface ABOVE the focus in an earthquake

A

epicenter

80
Q

how are earthquakes ordered

A

on a scale of magnitude with each increase in level representing 10 times the strength

81
Q

compare a magnitude 6 earthquake to a magnitude 5 earthquake

A

6 is 10 times STRONGER then a 5

82
Q

aftershocks refer to the

A

further slippage along fault lines (for earthquakes)

83
Q

how do we record earthquake magnitudes

A

with seismographs

84
Q

volcanoes have molten rock from the

A

asthenosphere

85
Q

steps in a volcanic eruption

A
  1. magma is expelled from underground (becomes lava) where it is still molten
  2. gases and pyroclastics are also ejected
86
Q

how many active volcanoes are there in the world

A

550

87
Q

where are volcanoes (3 locations)

A
  1. subduction boundaries
  2. sea-floor spreading centers
  3. hot spots
88
Q

what kind of volcanic location is Iceland

A

a hot spot AND a plate boundary

89
Q

the type of volcanic activity is dependent on

A

the magmas chemistry (make up( and viscosity

90
Q

two types of volcanic ACTIVITY

A
  1. effusive
  2. explosive
91
Q

effusive volcanic activity

A
  1. low viscosity magma
  2. with less than 50% silicon while rich in iron and magnesium
92
Q

effusive or explosive volcanic activity
Gentle with lava pouring onto the surface with small explosions

A

effusive

93
Q

effusive or explosive volcanic activity
found in sea-floor spreading and hot spots

A

effusive

94
Q

effusive or explosive volcanic activity
dramatic with explosions made from built-up gases, lava and pyroclastics

A

explosive

95
Q

effusive or explosive volcanic activity
are found in subduction zones

A

explosive

96
Q

explosive volcanic activity

A
  1. high viscosity magma
  2. 50 to 75% silicon and high in almunium
97
Q

types of volcanoes

A
  1. shield volcano
  2. composite cone volcano
  3. cinder cones
  4. caldera
98
Q

caldera is a

A

steep-sided, circular depression

99
Q

which type of volcano is this
collapsed volcanic cone

A

caldera

100
Q

Cinder cones

A

small features and made mostly from loose tephra (volcanic ash)

101
Q

what type of volcano is this
built around single vent

A

cinder cones

102
Q

what type of volcano is this
lava flow is rare

A

cinder cones

103
Q

what type of volcano is this
steep sided

A

cinder cone

104
Q

what type of volcano is this
steep and high elevations

A

composite cone volcanoes

105
Q

what type of volcano is this
very symmetrical

A

composite cone volcanoes

106
Q

what type of volcano is this
happen in subduction zones

A

composite cone volcanoes

107
Q

what type of volcano is this
a very explosive volcano

A

composite cone volcanoes

108
Q

what type of volcano is this
made from basaltic lava

A

shield volcanoes

109
Q

what type of volcano is this
less violent volcano

A

shield volcano

110
Q

what type of volcano is this
associated with hot spots and spreading zones

A

shield volcanoe

111
Q

what type of volcano is this
large horizontal dimensions

A

shield volcanoes

112
Q

what type of volcano is this
have gentle slopes

A

shield volcanoes

113
Q

what type of volcano is this

A

Shield volcano

114
Q

what type of volcano is this

A

shield volcano

115
Q

what type of volcano is this

A

Composite cone volcano

116
Q

what type of volcano is this

A

composite cone volcanoe

117
Q

what type of volcano is this

A

cinder cone

118
Q

what type of volcano is this

A

Caldera

119
Q

what plate is ALWAYS subducted in a subduction

A

ocean plate - it is always heavier

120
Q

what happens to the crust in a transform

A

it is NOT created NOR destroyed

121
Q

what type of plate boundary interaction results in the old crust being destroyed

A

convergent

122
Q

what type of plate boundary interaction results in new crust being created

A

divergent

123
Q

what is the force that affects on object

A

stress

124
Q

force where landforms RESULT from the stress

A

strain

125
Q

two types of strain

A

folding and faulting

126
Q

3 types of stress

A
  1. tension
  2. compression
  3. shear
127
Q

foreshock of an earthquake

A

movement BEFORE the main shock

128
Q

aftershock of an earthquake

A

movement AFTER the main shock

129
Q

p waves in an earthquake

A

faster and low impact that move like an accordion

130
Q

s waves in an earthquake

A

slower and more destructive that move like a wave

131
Q

what is the significance of the different waves seen in an earthquake

A

Different waves allow us to know the composition of the center of the Earth

132
Q

where does a volcano form

A

at the end of a vent

133
Q

where are craters found

A

near the summit of a volcano

134
Q

pyroclastic flow

A

air borne rock and rock fragments from vent

135
Q

what is the name for a pyroclast on the ground

A

tephra

136
Q

what forms from pyroclastic flows near a vent

A

cinder cones

137
Q

do cinder cones have lava

A

NO

138
Q

what is a hot spot and give an example

A

volcano forms but it is NOT at a plate boundary (example would be Hawaii)

139
Q

2 types of explosions in volcanoes

A
  1. effusive
  2. explosive
140
Q

what type of explosion is this
low viscosity magam

A

effusive

141
Q

what type of explosion is this
forms gentle sloping craters or volcano

A

effusive

142
Q

what type of explosion is this
found at cinder cones, shield volcanoes and plateau basalt

A

effusive

143
Q

what type of eruption is found in ocenas

A

effusive

144
Q

what type of explosion is this
high viscosity lava

A

explosive

145
Q

what type of explosion is this
found in composite volcanoes

A

explosive

146
Q

example of a shield volcano

A

in Hawaii

147
Q

example of a composite volcano

A
  1. St Helens
  2. Pompeii
  3. Japan