PLATE TECTONICS

Question 1

• State the initial evidence for the theory of continental drift and it shortcomings

Answer 1

o Continental drift
 Complimentary coastlines
 Fossil evidence
* Darwin’s theory of speciation
 Mountain belts
 Glaciation/ paleoclimates
* Climate being controlled by latitude
o Shortcomings
 Does not explain the driving mechanism for movement
 Found divergent boundaries in ocean

Question 2

modern evidence of plate tectonics

Answer 2

high resolution of global topography
magnetism
age of sea floor
plate velocity and vector data
earthquake and volcano distribution

Question 3

o Magnetism

Answer 3

 Lock orientation and polarity of earth magnetism, changed latitude
 Magnetic inclination
* Direction the crystal is pointing
o Flat when at the equator
* Depends on the latitude
 Apparent polar wandering
 Polarity
* Whether the magnetic dipole points N/S

Question 4

age of sea floor

Answer 4

 Youngest at the spreading center where lava forms

Question 5

plate velocity and vector data

Answer 5

 GPS reading shows plate movement to scale

Question 6

EQ and volcano distribution

Answer 6

 Where tectonic stresses are highest

Question 7

tectonic plate location

Answer 7

float on asthenosphere
consist of lithosphere

Question 8

boundary types

Answer 8

transform
divergent
convergent (O and O) (O and C)

Question 9

transform

Answer 9

 Plates slide past one another
 Small magnitude earthquakes, no significant topography change
 San andreas fault (California)

Question 10

divergent

Answer 10

 Two plates moving apart, resulting in upwelling of amntle material and magma
 At ocean ridges
 Continental rifting
* Eventually forms an ocean basin
* Mid-Atlantic ridge, Iceland, east African rift valley
 Features
* Most are under the ocean
* Minor earthquakes
* Volcanic activity
* Small scall topography at ridges

Question 11

convergent

Answer 11

 Oceanic -Continental subduction
* Mountain building
* Small- large earthquakes
* Explosive volcanoes
* Trench at boundary
o The Andes (left of south America)
 Oceanic – oceanic subduction
* Small- large earthquakes
* Volcanic island arc
* Trench at boundary
o Aleutian island, Japanese island arcs
 Continental – continental
* Large scale deformation and mountain building (orogeny)
o Mt Everest
* Features
o Earthquakes large – small
o Tallest topography

Question 12

• Explain the principle of isostacy and how its relevant to plate tectonics

Answer 12

o Less dense will float due to buoyant force
o The balance between buoyant force and gravity = isotacy
o This is the uplifting of magma from the asthenosphere

Question 13

• Explain how hot spots work and be able to provide examples

Answer 13

o Volcanic regions within plates, and is stationary
 Hawaii
o Rift valleys
 occurring due to tension of hot spot
 Continent thins until magma erupts and oceanic crust is creates

Question 14

• Understand how seafloor sediments can be used to infer a passive vs active margin

Answer 14

o Active margin
 Plates moves
o Passive margin
 Continent connected to ocean and no movement
 Shallow continental shelf extending into he ocean
* Shelf has a lot of thick sediments