Rocks Flashcards
What are the 3 types of rock?
- Sedimentary rock
- Igneous rock
- Metamorphic rock
What is sedimentary rock?
Rocks that are formed through the deposition of sediments, eg limestone, chalk and sandstone.
What is igneous rock?
Rocks that formed under very hot conditions within the Earth.
What is metamorphic rock?
A type of rock formed under intense heat or pressure.
What is compaction?
Compaction is what happens when sediments are squashed by the layers of sediment above them.
What happens when sediments are compacted?
When sediments are compacted, water between the grains is squeezed out and crystals of different salts form.
What can limestone be formed from?
Some limestones are formed from the shells of sea creatures
What are the 6 processes of sedimentary rock formation in order?
weathering → erosion → transportation → deposition → compaction → cementation
What is cementation?
After compaction the crystals stick the pieces of rock together like a glue. This process is called cementation.
What is transportation?
A river carries, or transports, pieces of eroded rock as it flows along.
What is deposition?
When the river reaches a lake or the sea, its load of transported rocks settles to the bottom. We say that the rocks are deposited.
What chemical makes up limestone?
Calcium carbonate
What is magma?
The inside of the Earth (mantle) is very hot - hot enough to melt rocks. Molten (liquid) rock is called magma. When the magma cools enough, it solidifies and igneous rock forms.
How are crystals formed?
Igneous rocks contain randomly arranged interlocking crystals. The size of the crystals depends on how quickly the molten magma solidified.
How are small crystals formed?
Lava that cools quickly will form an igneous rock with small crystals
How are large crystals formed?
Magma that cools slowly will form an igneous rock with large crystals.
What is lava?
The magma that comes out of volcanoes.
What is a volcano?
Magma builds up under the surface and gets forced through the crust.
Give examples of rock from cooled lava. Describe them.
Basalt and pumice both come from lava, which means they cooled quickly on the surface.
Basalt is a dark glassy rock which has very fine crystals often formed in columns.
Pumice is soft and cooled really fast.
Is granite cooled quickly or slowly?
Granite is found deep underground. It cooled very slowly and is very hard.
Does igneous rock contain fossils?
Igneous rocks do not contain any fossils. This is because any fossils in the original rock will have melted when the rock melted to form magma.
How are metamorphic rocks formed?
Shifting tectonic plates can cause rocks to be deeply buried or squeezed. As a result, the rocks are heated and put under great pressure. They do not melt, but the minerals they contain are changed chemically, forming metamorphic rocks.
Give examples of metamorphic rock
Marble is formed from limestone
Quartz is formed from sandstone
