2: Plate tectonics and igneous rocks

Question 1

What is the theory of ‘Continental Drift’?

Answer 1

Alfred Wegener published it in 1914
He noticed the shapes of the continents fit together therefore that they must have once been together and moved apart.
However was unable to explain
Disbelieved by most scientists until 1960s
Advances in scientists proved the mantle had convection currents which allowed the plates to move

Question 2

What is lava?

Answer 2

Molten rock that erupts from a volcano

Question 3

What is magma?

Answer 3

Liquid or molten rock under the Earth’s surface

Question 4

How do igneous rocks form?

Answer 4

When molten rock cools down, either underground or above ground it solidifies to form igneous rocks

Question 5

What determines the size of crystals in igneous rocks?

Answer 5

Rate of cooling
Lava cools quickly and magma cools slowly
The slower the rate of cooling, the larger the crystals become

Question 6

Basalt and Gabbro: similarities and differences

Answer 6

both rich in iron

gabbro has larger crystals because the molten rock cooled slowly

Question 7

Rhyolite and Granite: similarities and differences

Answer 7

both rich in a mineral called silica

granite has larger crystals

Question 8

Why do people live near volcanoes?

Answer 8

soil is fertile and rich in minerals which means plants grow well

Question 9

Different lava, different rock

Answer 9

Basalt is iron-rich an forms from runny lava.

Rhyolite is silica-rich and forms from thick lava producing lava bombs and volcanic ash.