Chapter 25 Flashcards
a system of mountain ranges on the seafloor separated by valleys
mid-ocean ridge
long,narrow depression that forms between peaks along the mid-ocean range
rift valley
the boundary where two plates collide
convergent plate boundary
when a thick and buoyant continental plate meets a thin and dense oceanic plate, the denser plate dives beneath the continent
subduction
the boundary between two plates that are moving apart
divergent plate boundary
a boundary where plates slide horizontally past each other in opposite directions
transform plate boundary
the sudden movement or vibration of the ground that occurs when rocks slip and slide along enormous cracks in Earth’s crusts
earthquake
a crack in the Earth’s crust along which rock has moved
fault
a sudden release of strain energy as rock moves along a fault
elastic rebound
the point of origin for an earthquake
focus
the point on Earth’s surface directly above the focus
epicenter
Who came up with the continental drift hypothesis
Alfred Wegner
What were some pieces of evidence that was backing up this hypothesis
- fossils, large land animals
- coastlines matched up like puzzle pieces
- mountain range matched up with the same rock type and age
What was the name of the super continent
Pangaea
Who cam up with the seafloor spreading hypothesis
Harry Hess
How did Harry Hess discover seafloor spreading
He used sonar
What did Hess discover using the sonar
mid-ocean ridge
What are the types of plate boundaries
- convergent plate boundary
- divergent plate boundary
- transform plate boundary
How do convergent plate boundaries move
The move together and converge or collide
Subduction zones occur with which type of plate boundary
Convergent plate boundaries
What two types of crust that are used with plate boundaries
- oceanic crust
2. continental crust
What types of land forms can be formed when 2 oceanic crust converge
- volcanic islands
2. deep sea trenches
What types of land form is created when two continental crust converge
mountains
What type of crust must be present for a volcanic activity to occur
oceanic crust
How do divergent plate boundaries move
They move away from each other
What are some example of divergent plate boundaries
- MOR- 2 oceanic crusts
2. East African Rift (2 continental crust)
How do transform plate boundaries move
They slide past each other
What is a specific example of a transform plate boundary
San Andres Fault (continental crust)
What is a convection current
- magma heats up, becomes less dense, and rises
2. magma, cools, becomes more dense, and sinks
What are three forces to contribute to plate motion
- slab pull
- ridge push
- friction
