chapter 25 Flashcards
A system of mountain ranges on the sea floor 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
A sudden movement or vibrations of the ground that occurs when rocks slip and slide along enormous cracks in Earths crust faults.
earthquake
A crack in Earths crust along which rock has moved.
fault
A sudden release of strain as rock moves along a fault.
elastic rebound
The point of origin for an earthquake.
focus
The point on earths surface directly above the focus.
epicenter
who came up with the continental drift hypothesis.
Alfred Wegener
what were some pieces of evidence that supported Wegeners hypothesis.
- large land animal fossils
- coast lines fit together like puzzles
- mountain ranges matched up with the same rock types
what was the name of the super continent.
Pangaea
who came up with the seafloor spreading hypothesis.
Harry Hess
How did Harry Hess discover seafloor spreading.
He used sonar which emitted waves that bounced off the seafloor
what did Hess discover using the sonar.
mid-ocean range
what are the types of plate boundaries.
- convergent plate boundary
- divergent plate boundary
- transform plate boundary
how do convergent plate boundaries move.
They move into each other, come together
subduction zones only happen with which type of plate boundary.
convergent plate boundary
what two types of crusts can happen or be used with any plate boundaries.
oceanic crust and continental crust
what two types of land forms can be formed when oceanic and continental crusts converge.
volcanoes and deep sea trenches
What types of land forms can be created when two oceanic crusts converge.
Deep sea trenches and hot spots which create volcanic islands
what types of land forms are 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 or away
What are examples of divergent plate boundaries.
MOR(mid ocean ridge), Oceanic crusts, East African Rift( two continental crusts)
How do transform plate boundaries move.
they move past each other.
what is a specific example of a transform plate boundary.
San Andreas fall (continental crust)
what is a convection current.
- Magma heats up, becomes less dense and rises
2. Magma cools and becomes more dense and sinks
What are three forces that contribute to plate motion.
Slab pull, Ridge push, and Friction
what is an earthquake.
The sudden movement or vibration of the ground that occurs when rocks slip and slide along faults
which plate boundaries have shallow earthquakes.
divergent and transform.
which plate boundary has deep earthquakes.
convergent boundaries.
what are the types of stress that can act upon rock to make it active/move.
compression, tension, shear, and torsion
what are the two types of deformation.
elastic and plastic
what happens to a rock when elastic deformation happens.
The material goes back to its original shape
what happens to a rock when plastic deformation happens.
It takes on a new shape
how many types of seismic waves are there.
primary waves, secondary waves, surface waves
what type of seismic waves is the fastest.
Primary waves
what type of wave is a primary wave.
it is a compression wave
what type of materials can p-waves pass through.
solids and liquids
what type of wave is an s-wave.
a transverse wave
what types of materials can an s-wave pass through.
only solids
which wave does the most damage and is more complex.
surface waves
what are the two skills that help measure earthquakes.
Richter scale and Mercalli scale
what does the Richter scale measure about and earthquake.
the amount of energy
what does the Mercalli scale measure about an earthquake.
the amount of visible damage
