Rock Types

Question 1

What are rocks?

Answer 1

Rocks are naturally occurring mixtures of one or more minerals or organic matter.

Question 2

How are rocks classified?

Answer 2

Rocks are classified by how they are formed, their composition & texture.

Question 3

How are igneous rocks formed?

Answer 3

They are formed by magma freezing at a temperature between 700°C - 1250°C. They are a mixture of many minerals.

Question 4

What are some types of igneous rock?

Answer 4

Felsic: light-colored rocks rich in elements such as aluminium, potassium, silicon & sodium
Mafic: dark colored, rich in calcium, iron & magnesium, poor in silicon

Question 5

Coarse/Fine grained igneous rocks:

Answer 5

Coarse-grained: takes longer to cool, giving mineral crystals more time to grow
Fine-grained: cools quickly, doesn’t allow crystals to be formed

Question 6

Extrusive vs intrusive igneous rocks:

Answer 6

Intrusive: magma pushes surrounding rocks below the Earth’s surface
Extrusive: forms when magma erupts onto Earth’s surface, cooling quickly with very little to no crystals

Question 7

What are sedimentary rocks?

Answer 7

These rocks are formed by erosion wearing down rocks and them gathering as sediment being deposited in layers. These layers become compacted & cemented together. No heat or pressure involved.

Question 8

What is a strata?

Answer 8

A strata is a layer of rocks, the process of sedimentary rocks is through stratification

Question 9

What are some types of sedimentary rocks?

Answer 9

Clastic: made of fragments of rock cemented together with calcite or quartz
Limestone: composed primarily of calcium carbonate in form of mineral calcite, formed in clear shallow waters
Coal: organic, accumulation of preserved plant materials usually in a swamp environment

Question 10

What are chemical sedimentary rocks?

Answer 10

Minerals crystallised out of a solution to become rocks.

Question 11

What are organic sedimentary rocks?

Answer 11

These are remains of plants and animals

Question 12

What is metamorphic rock?

Answer 12

These rocks change with temperature but remain solid. Takes place deep below the Earth’s surface.

Question 13

Contact metamorphism:

Answer 13

heated by nearby magma
increase temperature changes composition of the rock, old minerals changed into new minerals

Question 14

Types of metamorphic rocks:

Answer 14

Hornfel: fine-grained, non-foliated, produced by contact metamorphism
Marble: non-foliated, metamorphism of lime, calcium carbonate

Question 15

Regional Metamorphism:

Answer 15

pressure builds up in rocks deep within the Earth
large pieces of Earth’s crust collide and the rock is deformed chemically by the heat and pressure

Question 16

What does foliated mean?

Answer 16

Contains aligned grains of flat minerals.

Question 17

What is relative dating?

Answer 17

Relative dating does not give exact ages by using different pieces of information about the rock tp the determine the relative age. It is often found by it compared to the rocks surrounding them.