Plate Tectonics Flashcards
What does the Earth have?
A magnetic field
What does it change?
Polarity every million years
When combined with seafloor spreading what happens?
It produces rock stripes of alternating polarity
How can Geologists see how quickly crust is forming
By the width of the stripes
When does this occur?
At the constructive plate boundaries, where the plates are moving apart
What happens when oceanic and continental plates collide?
The denser oceanic plate is forced under the continental plate.
What is this called?
Subduction
What happens to the oceanic plate?
It melts and molten rock can rise to form volcanoes
Where does this occur?
At the Destructive plate boundaries
How do mountain ranges form?
Along colliding plate boundaries as sedimentary rock is forced up by the pressure created in a collision
Where do Earthquakes occur most frequently?
Plate boundaries
What are the 3 steps?
- The plates slide past each other or collide
- Pressure builds up as plates push on each other
- Eventually, stored energy is released and waves of energy spread from the epicentre
Plate movement is crucial in the rock cycle, what are the 4 steps?
- Old rock is estroyed through subduction
- Igneous rock is formed when magma reaches the surface
- Plate collisions can produce high temperatures and pressure, causing the rock to fold
- Sedimentary rock become metamorphic rock
