CH 25 Flashcards
Mountain ranges on the seafloor separated by valleys
Mid-ocean ridge
A long, narrow depression that forms in between peaks along the mid-ocean ridge
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 move apart along the mid-ocean ridge
Divergent plate boundary
Boundary where plates slide horizontally past each other in opposite directions
Transform plate boundary
A sudden movement of the ground that occurs when rocks slip along cracks in the Earth’s crust called faults
earthquake
A crack in the Earth’s crust along which the rock moves
Fault
Produces energy called seismic waves that travel in the Earth.
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?
Wegener
Evidence that Wegnere found to support his hypothesis.
- coast lines match up like puzzles pieces
- Large land animal fossils
- mountain ranges match up and the rocks are made up of the same compostion and age
What was the name of the super continent?
Pangeea
Who came up with the seafloor spreading hypothesis?
Harry Hess
What did Harry Hess use to map the bottom of the seafloor?
Sonar
Who discovered the mid-ocean ridge?
Harry Hess
Where is the youngest rock on the ocean floor located?
MOR
What are the types of plate boundary’s?
- Divergent
- Convergent
- Transform
How do convergent plate boundaries move?
The connect or come together
subduction zones only occur with which type of plate boundary?
Convergent plate boundaries
What two types of crust are involved in plate movement?
Oceanic and continental crust
What are the types of land forms can be created when oceanic and continental crusts converge?
Volcanoes and deep sea trench
What land forms can be created when two oceanic crusts converge?
deep sea trench and hot spots(creates islands)
What land forms are created when two continental crusts converge?
Mountains
How do divergent plate boundaries move?
Away from each other
What are the two examples of divergent boundaries?
MOR and east African ridge
How do Transform plate boundaries move?
They slide by each other
What is a specific example of a transform plate boundary?
San Andreas Fault (2 continental crusts)
How does a convection current work?
- magma heats up, then rises, cools down
2. cools down, sinks, goes down
what are other forces that help plate movement?
Ridge push, slab pull, and friction
what types of plate boundaries have shallow earthquakes?
Divergent and transform
Which boundaries have deep earthquakes?
convergent plate boundaries
What are the four types of stress that can be applied to rocks?
- compression
- tension
- shear
- torsion
What are the types of deformation?
elastic and plastic
What happens to the rock if elastic deformation occurs?
as soon as the stress is released it returns to its original shape
What happens to the rock if plastic deformation occurs?
as soon as the stress is released it remains in its new form
What types of seismic waves are there?
primary, secondary,and surface waves
Which type of seismic wave moves the fastest?
primary wave
What type of wave is a p wave?
compression waves
What type of wave is s wave?
Transverse
What types of material can p waves move through?
solids and liquids
What types of materials can s waves move through?
solids
Which waves are the most complex?
Surface waves
What are the two scales that help us measure earth quakes?
Ricther and mercali
what does the ricther scale measure?
amount of energy released
what does the mercali scale measure?
Damage caused
