Continental Drift & Plate Tectonics

Question 1

Crust

Answer 1

Oceanic
- 5 - 10km
- Basaltic, silicone and magnesium

Continental
- Average: 35km
- least: 30km
- Most: 70km
- Granitic, silicone, aluminium

Question 2

What is the Moho(rovicic) discontinuity?

Answer 2

Mantle and crust boundary.

Question 3

Lithosphere

Answer 3

Crust and upper most part of the mantle.

Broken into tectonic plates.

Question 4

Astenosphere

Answer 4

Layer below the lithosphere.

Has convection currents which move tectonics.

Question 5

Alfred wegner

Answer 5

Theory of Continental drift.

1912

Proposed idea of pangea from 250 million years ago.

Evidence:
- Geographical fit of continents
- Glaciation in southern continents
- Similar fossils found in places far apart

Question 6

Divergent plate boundaries

Answer 6

Constructive

Two plates moving apart

Magma rises up from asthenosphere and forces its way to the surface.

Mostly mid ocean ridges
- average depth 2.5km
- 60,000km total length

Question 7

Convergent

Answer 7

Oceanic - continental
- denser oceanic plate forced under less dense continental plate
- Subduction = trench

Oceanic - oceanic
- Slightly denser one will be subducted
- Also creates a trench

Continental - continental
- Little to no subduction
- Cretes mountains i.e Himalayas

Question 8

Conservative (transform) plate boundaries

Answer 8

Neither plate converges or diverges

Not many landforms

Potential for earthquakes if plates moving at different rates or opposite directions

I.e San Andreas fault, California.