Seafloor Spreading and Plate Boundary Movements Flashcards

1
Q

endogenic processes

A

earthquakes, diastrophism/deformation, magmatism, metamorphism

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

exogenic processes

A

weathering, erosion, deposition, sedimentation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

how does endogenic processes go

A

internal heat - mantle convection current - plate movement - endogenic processes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

what is the driving force of endogenic

A

earth’s internal heat

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

theories about plate movement

A

continental drift, seafloor spreading, tectonic plates

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

A theory stating that the Earth’s continents have been joined together and have moved away from each other at different times in the Earth’s history.
- developed the new continents we have today

A

continental drift theory

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

who proposed the continental drift theory and when

A

German Meteorologist Alfred
Wegener (1915)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

a supercontinent that existed during the late Paleozoic and early Mesozoic eras.
- single landmass

A

Pangaea

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

After many years Pangaea split into ________ and _________

A

Gondwanaland and Laurasia

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Evidence of Continental Drift Theory

A
  • Fit of Continental Shorelines
  • Rock Distribution
  • Glacial Sediments
  • Paleoclimate
  • Fossil Distribution
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Evidence of Continental Drift Theory

Explain shoreline fit and rock distribution

A
  • Continent’s shape looks like puzzle pieces
  • Same rocks and landforms are found on the shore of continents

(e.g. North America, Africa, South America)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Evidence of Continental Drift Theory

Explain glacial sediments

A

Glacial deposits from South America, Africa, India, and Australia are similar to Antarctica

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Evidence of Continental Drift Theory

Explain paleoclimate

A
  • Tropical Plant Fossils in Antarctica
  • Coal Deposit in Northern/Eastern
    Europe

coal and these plants thrive in tropical environments. hence, this suggests that these continents once had a tropical climate.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Evidence of Continental Drift Theory

Explain fossil distribution

A

Fossils of a shallow-water reptile, Mesosaurus, were found in both Africa and South America even though they could not swim across the Atlantic Ocean. Fossils of a family of seed ferns, Glossopteris, were found in Africa, South America, India, and Antarctica. These and a number of other fossil groups had identical populations separated by thousands of kilometers of ocean. Paleontologists called on implausible land bridges connecting the continents. But Wegener argued that rising and falling land bridges in the oceans were not likely considering the observation that the ocean crust was made of denser (basaltic) rock than the continents. He argued that this denser oceanic crust could not rise up above sea level. Likewise, if the land bridge was less dense (granitic) continental rock it would be too light to sink into the denser rock below.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

despite the pieces of evidence, why was the continental drift theory not accepted?

A

unclear mechanism of the plate movement
- Wegener thought that the Earth’s spin caused the movement, (spin theory) but geologists knew that the continents were far too heavy to be moved by Earth’s rotation
- argued that the world we see is the result of extreme events like worldwide floods and volcanoes. All the world’s continents wrenching themselves apart from a single landmass would certainly qualify as a catastrophe. (catastrophic theory)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

the mechanism by which new oceanic lithosphere is created at and moves away from divergent plate boundaries.
- New oceanic crust is formed due to the rising of hot, less dense material on the ocean floor

A

seafloor spreading theory

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

who proposed the seafloor spreading theory

A

Using data from SONAR-equipped vessels, oceanic cartographer Marie Tharp was able to create maps of the ocean floor that revealed the presence of underwater mountain ranges.
- proposed by the American geophysicist Harry H. Hess in 1960 based on Tharp’s discovery

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

Observations that support the Seafloor Spreading

A
  • Increasing distance between continents
  • Age of rocks in oceanic ridges
  • Thickness of rocks along oceanic ridges
  • Deposition of sediments away from the ridge
  • Magnetic Anomalies
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

Observations that support the Seafloor Spreading

explain the increasing distance between continents

A

e.g. The North American and Eurasian tectonic plates are moving away from each other at
the rate of about 2.5 centimeters (1 inch) per year

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

Observations that support the Seafloor Spreading

explain the age of rocks in oceanic ridges

A
  • younger/newer rocks are found at the ridge
  • the age of the seafloor is progressively older away from midocean ridges
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

Observations that support the Seafloor Spreading

Explain the Thickness of rocks along oceanic ridges

A
  • Along with the seafloor rock, scientists also hypothesized and proved that sediment accumulation must be thicker the farther away from the ridge they are. This is due to older rocks having more time to accumulate sediments than newly-formed rocks.
  • ( the elevation of the seafloor is progressively lower away from midocean ridges but the crust tends to bulk up and gets thicker as they get compressed with other rocks)
22
Q

Observations that support the Seafloor Spreading

Explain the deposition of sediments away from the ridge

A
  • older parts of the seafloor have the greatest potential to have accumulated sediments over
    the longest time
  • sedimentary rocks are found further from the ridge
23
Q

Observations that support the Seafloor Spreading

Explain magnetic anomalies

A
  • the magnetic history of the seafloor bears the striped-pattern of the Earth’s magnetic reversals

Periodically, the magnetic poles of the Earth flip, north and south becoming reversed. This phenomenon is then recorded in the magma that forms in ridges, having the minerals in the rock to match the polarity of the Earth when it was formed. These create bands of varying polarity and when observed using a magnetometer, the patterns created are mirrored on both sides of the ridge.

24
Q

example of landforms produced by seafloor spreading

A
  • Atlantic mid-ocean ridges
  • east pacific rise (pacific ocean)
25
why does seafloor spreading occur
because of mantle convection
26
Unifies the concepts of continental drift, seafloor spreading, magnetic field reversal, and other geological and geophysical discoveries. * States that lithosphere is not a continuous layer but consists of several-irregularly shaped pieces called Tectonic Plates. * Plates move and interact in Plate Boundaries - bc of mantle convection
plate tectonic theory
27
if some plates diverge/move away from each other, why does the earth not expand?
because of convergent boundaries/subduction caused also by mantle convection
28
plate boundary movements
convergence, divergence, transform
29
the motion/stress of convergent plate boundary
subduction/compressional
30
is there volcanic activity in a convergent plate boundary
yes
31
land formation of convergent boundaries
oceanic to continental (oceanic subducts) - cascades volcano/volcanic arcs (through flux melting, sa continental) - trenches oceanic to oceanic (older denser oceanic subducts) - trenches - volcanic arc/islands (through flux melting) continental to continental - geologic folds - ductile deformation due to compressional stress - mountains/mountain ranges
32
a fold that is arched upward to form a ridge
anticline
33
a fold that arches downward to form a trough
syncline
34
step-like fold in rock strata consisting of a zone of steeper dip within an otherwise horizontal or gently-dipping sequence. (forms a plateau)
monocline
35
-Happens when one fold is pushed over the other limb due to increasing compression. -Both limbs are sloping in the same direction.
overturned fold
36
the motion/stress of divergent plate boundary
spreading/tensional
37
the effect of divergent plate boundary
constructive (oceanic lithosphere is created)
38
is there volcanic activity in a convergent plate boundary
yes
39
land formation of divergent boundaries
continental to continental - Joints- brittle deformation in surface rocks due to tensional stress. - fissure volcanoes (Icelandic) - rift valleys oceanic to oceanic - oceanic ridges (seafloor spreading, decompression melting)
40
the motion/stress of transform plate boundary
lateral sliding/shearing
41
the effect of transform plate boundary
conservative (lithosphere is neither created or destroyed)
42
is there volcanic activity in a transform plate boundary
no
43
land formations of transform plate boundary
none, except faults (brittle deformation and may vary based on plate movement) there are earthquakes
44
the san Andreas fault is a combination of what plate boundary movement
transform and convergent
45
what fault does convergent plate boundary produce - hanging wall pushed up despite gravity
reverse fault
46
what fault does divergent plate boundary produce - lower hanging wall (because of gravity)
normal fault
47
what fault does the transform plate boundary produce
strike-slip fault
48
the rock above the fault zone - acute
hanging wall
49
he rock below the fault zone
foot wall
50
Do all plate boundary movements produce faults?
In order to produce faults, the rocks along these boundaries must obtain their fracture stage. Hence, not all plate boundary movements produce faults.