Plate tectonics Flashcards
(147 cards)
1
Q
who came up with the continental drift theory
A
Alfred Wegener
2
Q
Continental Drift Theory
A
that the continents used to form one supercontinent but began to drift a part into their current positions
3
Q
when was continental drift widely accepted
A
1950
4
Q
why was the theory of continental drift NOT taken seriously at first
A
because there was no mechanism that could be explained
5
Q
what were the two large portions that made up Pangaea
A
- Laurasia
- Gondwanaland
6
Q
what happened to the continents 135 MYA
A
separated to more present shape WITHOUT separating too much
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
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.
9
Q
describe polar position of the continents 440 MYA
A
polar position - yes
ice sheets - yes
10
Q
describe polar position of the continents 390 MYA
A
polar position - yes
ice sheets - no
11
Q
describe polar position of the continents 300 MYA
A
polar position - yes
ice sheets - yes
12
Q
describe polar position of the continents 260 MYA
A
polar position - yes
ice sheets - yes
13
Q
do the location of continents and whether they are together or separate affect weather
A
YES
14
Q
where is slow flow
A
in the upper mantle
15
Q
what drives slow flow and continent movements
A
convection cells
16
Q
steps within the convection cells
A
- heating of the material in the mantle
- the hot material rises
- begins to move outwards
- cools
- eventually there will be collisions and subduction
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
18
Q
curst formation steps
A
- material from the asthenosphere upwells along the sea floor and becomes extrusive igneous rock
- the oceanic crust is subducted under the lighter continental crust
- the subducted oceanic crust begins to melt
- melting generates magma = forms igneous intrusion rock and extrusive explosions
19
Q
what is the range of speed for the movement of continents
A
from 1 to 12cm per year
20
Q
how can the movement of continents differ
A
- in their speed
- in their direction
- in their orientation
21
Q
what is the Wilson cycle focused on
A
the different formations of supercontinents in the past
22
Q
how many supercontinents were expected to have been formed in 3 billion years (Wilsons cycle)
A
5
23
Q
supercontinents act as
A
insulators - their mass traps geothermal heat in earth
24
Q
what are the 4 steps in the Wilson cycle
A
- assembly
- stability
- splitting
- reassembly
25
average Wilson cycle takes ____ years
500 Million
26
does assembly in the Wilsons cycle have to be complete
NO- it can be incomplete
27
3 main types of plate boundaries
1. convergent
2. divergent
3. transform
28
divergent plate boundary
plates move AWAY from each other
29
convergent plate boundary
plates move TOWARDS each other
30
transform plate boundary
plates move in OPPOSITE directions but they REMAIN together
31
types of convergent plates
1. convergent oceanic plates
2. convergent continental plates
3. convergent oceanic AND continental plates
32
convergent plates results in _____
subduction
33
convergent OCEANIC plates results in
volcanic expression
34
convergent CONTINENTAL plates results in
formation of mountains (such as the Himalayas)
35
convergent of OCEANIC AND CONTINENTAL plates results in
volcanic activity
36
divergent CONTINENTAL plates results in
rift valleys and sometimes divots
37
TRANSFORM plates can be identified by
1. ridges not lining up
38
3 main STRESS types of crust deformation
1. tension
2. compression
3. shear
39
crust deformation
tension AKA
stretching
40
crust deformation
compression AKA
shortening
41
crust deformation
shear AKA
twisting
42
the stress of curst deformation results in
STRAIN
43
two examples of strains caused by crust deformation stress
1. folding (bending)
2. faulting (breaking)
44
what causes folding
compression at convergent plates
45
what are examples of the result of folding
basins and domes
46
anticlines and synclines in folding
the up and down folds that usually occur together and are caused by compressional stress
47
anticlines vs synclines of folding
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.
48
shear stress
49
shear stress results in
fault and bending horizontally
50
compression
51
compression results in ____ surface expression(s)
1. folding
2. faulting
52
tension
53
tension results in _____ surface expression
thining crust
54
what causes faulting
forces on both sides of a plate that causes fracture of material (break)
55
what are three examples of faulting
1. normal fault
2. thrust fault
3. strike-slip fault
56
what causes a normal fault
tension
57
how do identify a normal fault
when the hanging-wall side is displaced DOWNWARDS
58
what causes a thrust fault
compression
59
how to identify a thrust fault
the hanging-wall side moves UPWARD
60
what causes a strike-slip fault
shearing (twisting)
61
how to identify a strike-slip fault
have offset on the surface (ex. ridge lines DON'T line up)
62
is there vertical displacement in a strike-slip fault
NO
63
what fault is caused by diverging forces
normal fault
64
what fault is caused by converging forces
reverse/thrust fault
65
what fault is this
reverse/thrust fault
66
what fault is this
normal fault
67
what fault is this
strike-slip fault
68
orogenesis
mountain generation
69
examples of orogenesis
1. folding and faulting
2. plate collisions
3. addition of terranes
4. volcanic addition
5. uplift
70
what are some examples of plate interactions that cause orogenesis
1. continent to continent
2. ocean to continent
3. ocean to ocean
71
three mountain ranges formed by orogenesis
1. rocky mountains
2. Appalachians
3. Himalayas
72
what mountain range is this
Rocky Mountains
73
what mountain range is this
Appalachians
74
what mountain range is this
Himalayas
75
earthquakes are a
series of shocks caused by movement in the crust OR upper mantle
76
where do earthquakes often happen
along fault lines
77
center of earthquake movement
focus
78
where is the point of failure when referring to earthquakes
the focus
79
what is the point on the surface ABOVE the focus in an earthquake
epicenter
80
how are earthquakes ordered
on a scale of magnitude with each increase in level representing 10 times the strength
81
compare a magnitude 6 earthquake to a magnitude 5 earthquake
6 is 10 times STRONGER then a 5
82
aftershocks refer to the
further slippage along fault lines (for earthquakes)
83
how do we record earthquake magnitudes
with seismographs
84
volcanoes have molten rock from the
asthenosphere
85
steps in a volcanic eruption
1. magma is expelled from underground (becomes lava) where it is still molten
2. gases and pyroclastics are also ejected
86
how many active volcanoes are there in the world
550
87
where are volcanoes (3 locations)
1. subduction boundaries
2. sea-floor spreading centers
3. hot spots
88
what kind of volcanic location is Iceland
a hot spot AND a plate boundary
89
the type of volcanic activity is dependent on
the magmas chemistry (make up( and viscosity
90
two types of volcanic ACTIVITY
1. effusive
2. explosive
91
effusive volcanic activity
1. low viscosity magma
2. with less than 50% silicon while rich in iron and magnesium
92
effusive or explosive volcanic activity
Gentle with lava pouring onto the surface with small explosions
effusive
93
effusive or explosive volcanic activity
found in sea-floor spreading and hot spots
effusive
94
effusive or explosive volcanic activity
dramatic with explosions made from built-up gases, lava and pyroclastics
explosive
95
effusive or explosive volcanic activity
are found in subduction zones
explosive
96
explosive volcanic activity
1. high viscosity magma
2. 50 to 75% silicon and high in almunium
97
types of volcanoes
1. shield volcano
2. composite cone volcano
3. cinder cones
4. caldera
98
caldera is a
steep-sided, circular depression
99
which type of volcano is this
collapsed volcanic cone
caldera
100
Cinder cones
small features and made mostly from loose tephra (volcanic ash)
101
what type of volcano is this
built around single vent
cinder cones
102
what type of volcano is this
lava flow is rare
cinder cones
103
what type of volcano is this
steep sided
cinder cone
104
what type of volcano is this
steep and high elevations
composite cone volcanoes
105
what type of volcano is this
very symmetrical
composite cone volcanoes
106
what type of volcano is this
happen in subduction zones
composite cone volcanoes
107
what type of volcano is this
a very explosive volcano
composite cone volcanoes
108
what type of volcano is this
made from basaltic lava
shield volcanoes
109
what type of volcano is this
less violent volcano
shield volcano
110
what type of volcano is this
associated with hot spots and spreading zones
shield volcanoe
111
what type of volcano is this
large horizontal dimensions
shield volcanoes
112
what type of volcano is this
have gentle slopes
shield volcanoes
113
what type of volcano is this
Shield volcano
114
what type of volcano is this
shield volcano
115
what type of volcano is this
Composite cone volcano
116
what type of volcano is this
composite cone volcanoe
117
what type of volcano is this
cinder cone
118
what type of volcano is this
Caldera
119
what plate is ALWAYS subducted in a subduction
ocean plate - it is always heavier
120
what happens to the crust in a transform
it is NOT created NOR destroyed
121
what type of plate boundary interaction results in the old crust being destroyed
convergent
122
what type of plate boundary interaction results in new crust being created
divergent
123
what is the force that affects on object
stress
124
force where landforms RESULT from the stress
strain
125
two types of strain
folding and faulting
126
3 types of stress
1. tension
2. compression
3. shear
127
foreshock of an earthquake
movement BEFORE the main shock
128
aftershock of an earthquake
movement AFTER the main shock
129
p waves in an earthquake
faster and low impact that move like an accordion
130
s waves in an earthquake
slower and more destructive that move like a wave
131
what is the significance of the different waves seen in an earthquake
Different waves allow us to know the composition of the center of the Earth
132
where does a volcano form
at the end of a vent
133
where are craters found
near the summit of a volcano
134
pyroclastic flow
air borne rock and rock fragments from vent
135
what is the name for a pyroclast on the ground
tephra
136
what forms from pyroclastic flows near a vent
cinder cones
137
do cinder cones have lava
NO
138
what is a hot spot and give an example
volcano forms but it is NOT at a plate boundary (example would be Hawaii)
139
2 types of explosions in volcanoes
1. effusive
2. explosive
140
what type of explosion is this
low viscosity magam
effusive
141
what type of explosion is this
forms gentle sloping craters or volcano
effusive
142
what type of explosion is this
found at cinder cones, shield volcanoes and plateau basalt
effusive
143
what type of eruption is found in ocenas
effusive
144
what type of explosion is this
high viscosity lava
explosive
145
what type of explosion is this
found in composite volcanoes
explosive
146
example of a shield volcano
in Hawaii
147
example of a composite volcano
1. St Helens
2. Pompeii
3. Japan
