Plate Tectonics Flashcards
How many plates is the lithosphere broken up into?
20
How flexible is the lithosphere?
bends elastic
How flexible is the Asthenosphere?
flows plastically
What is continental drift?
The theory is that the lithosphere was once one supercontinent called Pangea.
What was the evidence to prove continental drift?
Sedimentary rocks
Identical fossils
Matching geology
What is the mid-ocean ridge?
Linear mountain ranges in Earth’s ocean basins.
What is the 1rst step of sea floor spreading?
Magma erupts at the mid-ocean ridge.
What is the 2nd step to sea floor spreading?
New crust moves away from the ridges.
What is the third step to sea floor spreading?
At trenches, the sea floor dives back into the mantel.
What happens at divergent plate boundaries?
The plates move apart.
What are the two outcomes at a convergent plate boundary?
Subduction
They make a mountain
What do ocean-ocean convergent boundaries create?
Subduction
What does continent - continent-convergent boundaries create?
Builds mountains
What happens at a convergent plate boundary?
The tectonic plates move together.
What is subduction?
Ocean crust is pushed down into the mantel and is consumed(melted)
What happens at continent-ocean convergent boundaries?
Volcanic arcs
What is a volcanic arc?
The descending plate partially melts at 150km depth. The melt moves upwards and forms volcanos.
What happens at transform plate boundaries?
The tectonic plates slide past each other.
What is a hot spot?
volcanic plumes independent of tectonic plates.
What is Orogeny?
The process of forming mountains.
What is deformation?
Process by which rock bend break or flow in response to stress.
What three mechanisms drive plate tectonics?
Ridge - push
Slab-pull
Convection
What is ridge-push?
Elevated Mid-ocean ridge pushes lithosphere away (gravity)
What is slab-pull?
Gravity pulls a subducting plate downward.
What is convection in the asthenosphere?
Cool oceanic plate sinks while hot rises from the mantel.
