Plate tectonics Flashcards
Describe the significance of plate tectonics
Plate tectonics explain the formation of landforms, create earthquakes and form volcanoes
Describe the process of seismic waves
Seismic waves are formed when energy is suddenly released from a source causing vibrations that propogate through the Earth.
What is a P-wave?
A P-wave (Primary wave) is a type of seismic wave that is the fastest, travels through solids, liquids, and gases, and moves back and forth in the same direction they travel.
What is an S-wave?
A Secondary wave (S-wave) arrives second, moves material side to side, perpendicular to their direction of travel and it can only travel through solids.
What is a shadow zone?
Places on the Earth where either P-waves or S-waves are unreadable.
What causes a shadow zone for P-waves and S-waves?
For P-waves this is caused by them redirecting once passing through liquid.
For S-waves this is caused by the inability to move through liquid past the earth’s solid core.
What is the lithosphere?
The outer solid part of the Earth, including the crust and uppermost mantle and it forms lithospheric plates.
What is the Wilson cycle?
Plates are formed, deformed and destroyed over.
What is a convergent boundary?
Convergent boundaries are destructive and is when plates come together.
What is a divergent boundary?
Constructive and when plate move apart
What is a transform boundary?
Plates sliding past each other, causing faults
What is a convection current?
Warm material rises, cold material sinks
What is a slab pull?
Plates older and colder sink at subduction zones
What is a ridge push?
Gravity moves the tectonic plates away from a mid-ocean ridges
What did Alfred Wegener find?
The fit of continents and their similar rock types.
What was Tharp’s work?
Proved the existence of mid-ocean ridges, rift valleys and proved that continents are drifting apart.
She creates a definitive map of the ocean’s floor
What did Harry Hess discover?
Theory of seafloor spreading
What is seafloor spreading?
The process where new oceanic crust forms at mid-ocean ridges and moves outwards.
How is the age of the Earth’s crust measured?
Passing a magnetometer over a mid ocean ridge gets a symmetrical pattern (acting as a tape recorder)
How are mid-ocean ridges created?
At spreading centers (like the mid-Atlantic ridge), new crust is added to the edges of the plates.
How do hot spots form volcanoes?
A volcano is formed from a tectonic plate moving above it
What is a hot spot?
Hot magma rising from deep in the Earth’s mantle
What is intraplate activity?
Activity that occurs from stress within a plate far from a plate boundary
What is a subduction zone?
A type of convergent boundary whereby plates sink beneath another plate.
What cases do subduction zones occur and which cases do they not?
Oceanic-continental convergence
Oceanic-oceanic convergence
Not occur:
Continental-continental convergence
