Rock types
What are the 3 main types of rocks?
Igneous, sedimentary and metamorphic
What is magma?
Molten rock beneath Earth's surface
What are sediments?
Small pieces of rock, minerals or organic material
What does the word "metamorphic" mean?
Changed in form
What is the rock cycle?
The continuous process where rocks are formed, broken down and changed into other types of rocks.
Which type of rock forms when magma or lava cools and solidifies?
Igneous
What is lava?
Molten rock that reaches Earth's surface
What process breaks rocks into smaller pieces?
Weathering
What two factors cause metamorphism?
heat and pressure
What process turns rock into sediment?
Weathering and erosion
Which type of rock forms from compacted and cemented sediments?
Sedimentary
What are the two types of igneous rocks?
Intrusive and extrusive
What is compaction?
The process where layers of sediment are pressed together by the weight above them.
Does a rock melt when it becomes metamorphic?
No. It remains solid but is changed by heat and/or pressure.
What processes turn sediment into sedimentary rock?
Compaction and cementation
Which type of rock forms when existing rock is changed by heat and pressure?
Metamorphic
What is the difference between intrusive and extrusive igneous rocks?
Intrusive rocks cool underground; extrusive rocks cool at Earth's surface.
What is cementation?
The process where dissolved minerals bind sediment particles together.
How can heat change an existing rock?
It can cause minerals to recrystallise or change.
What process turns existing rock into metamorphic rock?
Heat and pressure
A rock contains layers of sediment and may contain fossils. What type of rock is it?
Sedimentary - bioclastic
Why do intrusive igneous rocks usually have larger crystals than extrusive rocks?
They cool slowly underground, giving crystals more time to grow.
Why do sedimentary rocks often form in layers?
Sediments are deposited in layers over time, with newer layers forming on top of older ones.
A sedimentary rock is buried deep underground and exposed to intense heat and pressure. What type of rock could it become?
Metamorphic rock
What process must occur for any rock to become an igneous rock?
The rock must melt into magma and then cool and solidify.