Year 8 Geology

List the 4 layers of the Earth

The four layers of the Earth are the inner core, outer core, mantle, and crust.

Define ‘mineral’

A naturally occurring inorganic substance that make up rocks, for example salt

Define ‘rock’

A solid natural material made up of one or more minerals, for example sandstone

Define ‘soil’

the top layer of Earth’s surface, made up of minerals. Almost all Earth’s plants grow in soil

What are the three types of rocks?

Igneous, Sedimentary and Metamorphic

What is a mineral in terms of classifying minerals?

a regular repeating pattern that can form crystals

What is a crystal?

a mineral’s repeating pattern over and over again, which forms in geometric shapes

What is a gem

cut and polished crystals

What is a rock in terms of classifying minerals

Grains of different types of minerals

Colour

different minerals have different colours

Lustre

how shiny a material is or how well or reflects light

Hardness

Moh’s scale of hardness - the ability of a material to scratch other materials

Cleavage

the way minerals split or break

Streak test

the colour that is left behind when scratched on an unglazed white tile

Weathering

rocks breaking down into smaller peices, and can be classified into physical, chemical and biological weathering.

Physical weathering

when rocks break down into smaller peices by physical forces, for example temperature, water, wind, and freeze thaw

Biological weathering

The disintergration of rocks that is caused by living organisms, for example a burrowing animal

Chemical weathering

when rocks break down due to chemical reactions, for example acid rain in a highly polluted area

Erosion

carries rock fragments from one place to another. Agents of erosion include wind, water or gravity

Deposition

when sediment is deposited somewhere on the Earth’s surface, for example sediment falling off a cliff onto the land below