Everything Flashcards
What are the three main rock types?
Igneous, sedimentary and metamorphic rocks
How do extrusive igneous rocks form?
Extrusive igneous rocks form no crystals in the rock, meaning they have cooled very quickly once the magma has reached the Earth’s surface
How do intrusive igneous rocks form?
Intrusive igneous rocks form many crystals, meaning the magma has cooled very slowly and deeply into the Earth
Where are sédiments deposited?
Sea floors, rivers and lakes
How are sédiments transported?
By water, ice and wind
What can sédiments that form sedimentary rocks be eroded from?
Sedimentary, igneous or metamorphic rocks
Why do metamorphic rocks have deformed layers?
Due to the extreme heat and pressure used to meld the rock
What is the rock cycle?
A set of processes which convert rocks of one type into another type, of convert rock into sediment and back into rock again
Where can fossils form?
Only in sedimentary rock
How are fossils formed?
When an organism falls into mud when it dies
What is mechanical weathering?
The physical breaking down of a rock with no chemical components
What is chemical weathering?
The breaking of bonds through water, which chemically interacts with lattice in the minerals
What is sedimentation?
When sediment settles at the bottom of the ocean
What is compaction?
When sediment begins to compact due to the pressure above it
What is cementation?
When compaction eventually forms new rock
What are the two main processes of fossilisation?
Permineralization and replacement
What are trace fossils?
Indicators and clues of fossil behaviour such as footprints, burrows and bite marks
What is a body fossil?
Any part of an organisms body such as plates, bones or teeth
What is pressure?
Force applied to a given surface which can be increased by increasing the force or decreasing the area
What is the standard unit of pressure?
Pascal (Pa)
What is air pressure at sea level?
101.3 kPa
What is air pressure underground?
25000 kPa
What is metamorphic rock?
A rock that undergoes change through exposure to extreme heat or pressure
What is contact metamorphism caused by?
Extreme heat
What is regional metamorphism caused by?
Extreme pressure
What are the seven principles of stratigraphy?
Uniformitarianism, intrusive relationships, cross-cutting relationships, inclusion and components, original horizontality, superposition and faunal succession
What is superposition?
A principle of geology that states layers further down into rock strata are older than rocks further up
What are cross-cutting relationships?
A principle of geology that states the geologic feature that cuts another is the younger of the two features
How does the rock cycle begin?
When magma reaches the surface of the Earth and erupts from volcanoes as lava, which form igneous rocks
What is the second stage of the rock cycle?
Igneous rocks go through the processes of erosion, weathering, transport and deposition before forming sédiments
What is the third stage of the rock cycle?
Sédiments go through compaction and cementation before forming sedimentary rock
What is the fourth stage of the rock cycle?
Sedimentary rock goes through high pressure, high heat and burial before forming metamorphic rock
What is the final stage of the rock cycle?
Metamorphic rock melts to form magma
Why are diamonds so hard?
Because all their atoms are of an equal distance apart, making them very rigid and giving them a 10 on the Mohs Hardness Scale
