Plate Tectonics

Question 1

Earth’s Structure

Answer 1

Takes up 1% of Earth’s volume
Temp. varies from air temperature (at surface) to 1600℉ (at boundary)
Chemically speaking
- Crust
- Silicates (silicon + oxygen)
Mechanically speaking
- Lithosphere (crust + upper mantle)
- Rigid movement
Mantle
- Silicates at 100-2900km
Asthenosphere
- Ductile movement

Question 2

Alfred Wegener & Continental Drift Theory

Answer 2

Alfred Wegener - first to propose the idea that continents moved
Evidence
- Apparent fit of the continents
- Glacial evidence in tropical areas
- Distribution of fossils
- Matching geologic units

Question 3

Convection Currents

Answer 3

Convection current of the mantle is driving force of plate tectonics

Question 4

Plate Boundaries

Answer 4

Tectonic plates meet at plate boundaries

3 types of plate boundaries: convergent, divergent, and transform

Question 5

What is an earthquake?

Answer 5

A vibration caused by the sudden breaking or frictional sliding of rock in the Earth

Question 6

Magnitude

Answer 6

Measurement of energy released at the source, uses seismographs

Question 7

Intensity

Answer 7

The effect on Earth’s surface, location or site-dependent

Question 8

Plate Tectonics & Volcanism

Answer 8

Convergent Boundaries
- Subduction - one plate sinks beneath another. As the sinking plate gets closer to the hotter mantle, it melts. Produces magma.
- Continental - Oceanic: Continental Volcanic Arc
- Oceanic - Oceanic: Volcanic Island Arc

Question 9

Plate Tectonics & Volcanism

Answer 9

Divergent Boundaries
Continental - Continental: Volcanically active rift valleys as lithosphere gets thinner
Oceanic - Oceanic: Mid-ocean ridge volcanism as seafloor spreading pushes plates apart

Question 10

Convergent Boundaries

Answer 10

Boundary at which two plates are moving towards each other
Subduction - a convergent boundary at which one plate sinks under the other
Oceanic crust is being destroyed

Geologic Features:
Mountains
Earthquakes
Trench - forms as the plate bends and begins to subduct
Volcanic Arc - magma is formed as the subducting plate melts
Continental Volcanic Arc (Continental & Oceanic) vs. Volcanic Island Arc (Oceanic)

Question 11

Divergent Boundaries

Answer 11

A boundary at which two plates move apart from each other

Oceanic lithosphere (crust) is created at these ridges through seafloor spreading process

Geologic Features:
- Earthquakes
- Mid-ocean ridges
- Rift Valley

Question 12

Transform Boundaries

Answer 12

Boundary at which two plates slide sideways past each other

No new plate is created, no new plate is destroyed

Often link together ridge segments
Shallow earthquakes common