T3 - Geology Flashcards
What are the layers in the Earth
Crust
Mantle
Inner core
Outer Core
What is the composition of the Crust
Oceanic Crust:
- Silicon
- Oxygen
- Iron
- Magnesium
Continental Crust:
- Silicon
- Oxygen
- Aluminium
- Iron
- Calcium, Sodium and Potassium
The crust varies from 5k beneath the ocean to 70km under mountain ranges
What is the composition of the Mantle
Partially molten rock
Temperatures between 500 and 2000 degrees
About 2900 km thick
What is the composition of the inner core?
Solid
Mostly Fe and some Ni
(iron and Nickel)
What is the composition of the outer core?
Mostly Iron solid because of extreme pressure
Describe the Shrinking Earth Theory and ideas around the formation of geographical sites:
An old theory from the 20th century that proposed that the Earth has been gradually cooling and contracting causing the the diameter of the earth to shrink. This contraction was believed to create the folds and faults in the earth.
Describe the continental drift theory and ideas around the formation of geographical sites:
The continental drift theory proposed that the continents around the world moved over a denser material which we now know is the mantle and the convection currents.
Recognise the major plates on a map of the world:
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Explain the movement of tectonic plates in terms of heat and convection currents in the Earths mantle
Describe and compare the the process of subduction and the formation of mid ocean ridges
Mid ocean ridges are formed when there are divergent boundaries. This makes the magma come out of the crack. The magma pushes existing rock to the sides as it cools and comes out. This process is repeated
Subduction occurs at Oceanic to Continental boundaries. The oceanic crust goes beneath the continental crust and volcanoes are formed on the surface because of the crust melting. This process recycles the crust through a cycle.
Link the theory of seafloor spreading with the movement of tectonic plates and the formation of new oceanic crust
Describe the features of the three types of plate boundaries
Divergent Boundaries:
- Plates moving away from each other
Convergent Boundaries:
- Plates move towards each other
Transform Boundaries:
- Plates move sideways to each other
Give examples of each plate boundary
Divergent: Mid Atlantic Ridge
Convergent: Eurasian and Indian Plate
Transform: San Adreas Fault
Explain the meaning of the term hotspot and the significance of lines of hot spots giving examples
A hotspot is a volcanic region on land that is fed by the mantle below that is anonymously hotter than surrounding mantle
Describe and model the process of folding and faulting
The plates forces moving towards or away from each other are what create faults and folds
There are 3 possible forces that cause faults and folds:
1. Compressive
2. Tensional
3. Shearing
There are 2 types of folds:
Syncline and Anticline
Relate folding to the movement of tectonic plates and the formation of mountain ranges
As plates experience compressional forces and move together, they are squashed together and forced upwards forming mountains.
Explain the formation of faults in terms of the forces acting within the Earth’s crust and the movement of plates relative to each other
Faults are formed when there is a movement along a crack
Sideways movement along a fault is called a strike slip fault
Relate the occurrence of major earthquakes and volcanoes to the movement along plate boundaries
Major Earthquakes and volcanoes occur from plate movements because earthquakes occur when tension is released in the earth. The only way this can occur is through plate movement at boundaries.
Compare the energy released by different earthquakes with different values on the Richter Scale
Identify the main features of volcanoes
Ash Cloud: A cloud of ash formed by volcanic explosions
Vent: The opening in a volcano where lava comes out
Lava: Molten rock which has erupted
Crater: Mouth of volcano that surrounds vent
Sill: A flat piece of rock which forms by hardening of magma in a crack in the volcano
Summit: Highest Point
Ash: Small parts of lava or rock which are shot in the air.
Throat: Conduits part that ejects lava and volcanic ash
Conduit: The passage in the middle of the volcano where magma travels up
Describe the difference between lava and magma
Magma is molten rock that is beneath the earths surface and lava is magma that has erupted
Describe and compare the characteristics of active, dormant and extinct volcanoes
Active: Still erupting
Dormant: hasn’t erupted in 20+ years
Extinct: Hasn’t erupted in thousands in years
Relate the age and stability of the Australian continent and its lack of volcanic and major earthquake activity to its location
Australia has little earthquakes and volcanoes because of how war it is from any plate boundaries. Since earthquakes and volcanoes occur from moving plates.
List the different types of seismic waves and the direction of their movement
P-Waves: compressional waves, back and forth motion
S-Wave: transverse waves, travel perpendicular
Explain the difference between a seismogram and seismograph
Seismograph: an instrument that measures and records details of earthquakes, such as force and duration.
Seismogram: a record produced by a seismograph.
Amplitude definition?
The distance from the resting line and the highest s-wave
How do we know that the magnetic poles of the Earth flippped
We know this because of paleomagnetism. Paleomagnetism is where magnetic particles align with the magnetic field. This means that magnetic records are stored in rock as they cool and solidify from mid ocean ridges. This is also explains the plates tectonic theory
What are the different types of volcanoes?
Fissure Volcano
Shield Volcano
Dome Volcano
Ash Cinder Volcano
Composite Volcano
Caldera Volcano
Fissure Volcanoes?
Erupt at linear cracks
Shield volcano
Built by its highly fluid lava over constant eruptions. Its low viscosity allows the lava to spread thinly over the whole volcano
