Rocks Flashcards
What is geology?
Geology is the science and study of the Earth, it’s composition and structure, it’s history and the processes that currently shape it.
What are sedimentary rocks?
Sedimentary rocks are rocks that have formed through the accumulation and solidification of sediment.
What can you find in sedimentary rocks?
Fossils
How are sedimentary rocks laid down?
In layers.
What is sedimentation?
Sedimentation is the process of sediment building up in layers at the bottom of lakes/ rivers/ oceans.
What is compaction?
Compaction is when the weight of the sediments on top
squash the sediments at the bottom.
What is sediment?
Sediment is organic or mineral matter deposited by water, air or ice.
What is cementation?
Cementation is when water is squeezed out from between the rock and crystals of different salts form. These crystals form a glue that cements pieces of rock together.
How does sedimentary rock form?
Sediment deposited ↓ Sedimentation ↓ Compaction ↓ Cementation
These processes eventually make sedimentary rock. Sedimentary rock may take millions of years to form.
What does igneous mean?
Fiery
What is magma?
Molten rock formed when rocks melt.
What % of the Earth’s crust does igneous rock make up?
95%
How does igneous rock form?
When magma cools and solidifies.
What happens if magma cools quickly and what is formed?
If the magma cools quickly, small crystals form in the rock. They are called extrusive igneous rocks.
Why might extrusive igneous
rock form?
If it erupts from a volcano.
What are some examples of extrusive igneous rocks?
Obsidian, scoria and basalt
What happens if the magma cools slowly and what is formed?
If the magma cools slowly, large crystals form in the rock. They are called intrusive igneous rocks.
Why might intrusive igneous rock form?
If it cools deep underground.
What are some examples of intrusive igneous rocks?
Granite, diorite and gabbro
What are metamorphic rocks?
Metamorphic rocks are rocks that have formed from other rocks, whose structure has been changed by intense heat or pressure.
How are metamorphic rocks formed?
Earth’s movements can cause rocks to be deeply buried or squeezed
↓
As a result, the rocks are heated and put under great pressure
↓
The rocks do not melt, but the minerals they contain are changed chemically forming metamorphic rock.
What 2 things are required for a rock to change form?
Extreme heat and pressure
What are 5 examples of sedimentary rock?
Limestone Sandstone Shale Coal Flint
What are some examples of metamorphic rocks?
Marble Slate Quartzite Phyllite Schist
