1.2 Plate theories

Question 1

What are the two types of crust?

Answer 1

Continental crust = thicker crust which underlies the continents and its low density allows it to float on the dense mantle below
Oceanic crust = thinner crust which is denser

Question 2

What are the structural layers of the earth?

Answer 2

Core is in the middle and it is hottest here and consists of solid inner core and liquid outer core
Then it is the mantle which has hot and plastic rocks in the lower mantle and cool and brittle rocks in the upper mantle.
Rocks in the upper mantle are cool enough to break under stress and produce earthquakes but rocks in the lower mantle flow rather than breaking when under stress
Then comes the asthenosphere(part of mantle) and following that is the lithosphere which includes the crust and upper mantle

Question 3

What is mantle convection?

Answer 3

Heat which comes from the earth’s core(from radioactive decay) rises within mantle to drive convection currents, which in turn move the tectonic plates
These convection currents operate as cells and allows the plates to move in different directions when the cells come in contact which each other

Question 4

What is paleomagnetism?

Answer 4

Occurs at divergent plate boundaries when plates pull apart from each other under the sea.