Chapter 2 - Tectonic Plates Flashcards
Pangaea
The super-continent that Alfred Wegener believed that the continents were split up from.
Alfred Wegener
The meteorologist who who first proposed that the continents move and had once been one in a super-continent.
Continental Drift
The idea that the continents are slowly drifting apart.
What were the problems with Wegener’s initial theory?
1) He didn’t have a mechanism for how the continents moved.
2) He incorrectly believed that only the continents moved, when in fact, they are not independent of plates.
What caused continental drift theory to become legitimized?
The discovery of magnetic bands on the ocean floor which were eventually linked to ocean floor spreading
What are the three types of plate boundaries?
Divergent, Convergent, and Transform.
In what direction do divergent plates move?
Away from each other. Features a rift from which molten rock flows.
In what direction to convergent plates move?
Towards each other. Features subduction or collision.
In what direction do transform plates move?
Parallel to each other.
What are the main hazards along transform boundaries?
Earthquakes.
How do plates move?
Plates move by convection, a process of heat transfer in which hot material rises and cool material sinks. It is the driving force of plate tectonic theory.
What is the evidence that supports Wegner’s hypothesis of Pangaea?
Continental fit, patterns of present day animal life, fossil evidence, related rocks, and ancient climates.
Decompression melting
Melting that occurs at divergent boundaries. As mantle material rise toward the divergent plate boundary the pressure is drastically reduced.
What is subduction?
When one place with a higher density than another plate sinks beneath it.
Flux melting
Melting that occurs at convergent boundaries. Water is sucked down with the subducted material and helps melt material.
