Ch.25 Flashcards
a system of mountain ranges on 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
type of boundary where plates slide horizontally past each other in opposite directions
Transform Plate Boundary
the boundary between two plates that are moving apart
Divergent Plate Boundary
a sudden movement or vibration of the ground that occurs when rocks slip and slide along enormous cracks in Earth’s crust called faults
Earthquake
a crack in 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 Wegener
What were some pieces of evidence to support Wegener’s hypothesis ?
- Coastlines match up like puzzle pieces
- found large land animal fossils
- mountain ranges match up and the rocks are made up of the same composition and age
What was the name of the super continent?
Pangaea
Who came up with the Seafloor Spreading Hypothesis?
Harry Hess
What did Harry Hess use to map the bottom of the sea floor?
Sonar
Who discovered the mid-ocean ridge?
Harry Hess
Where at the bottom of the sea floor is the youngest rock gonna be found?
near the MOR (mid-ocean ridge)
What are the types of plate boundaries?
- Divergent
- Convergent
- Transform
How to convergent plate boundaries move?
They come together; collide
Subduction zones only occur with which type of plate boundary?
Convergent plate boundaries
What two types of crust are involved in plate movement?
Oceanic crust and Continental crust
What are the types of land forms that can be created when Oceanic and Continental crust converge ?
Deep-sea trench and volcanoes
What land forms are created when two Oceanic crust 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?
They separate
What are the two examples of divergent boundaries?
MOR(Oceanic crust) and East African Rift (continetal crust)
How do transform plate boundaries move?
They slide horizontally past each other
What is a specific example of a transform plate boundary?
San Andreas Fault (two continental crusts)
How does a convection current work?
- magma heats up, becomes less dense, and rises
2. magma cools, becomes more dense, and sinks back down
What are other forces that help plate movement ?
slab pull, ridge push, and friction
What types of plates boundaries have shallow earthquakes ?
divergent and transform
Which boundaries have deep earthquakes?
Convergent plate boundaries
What are the 4 types of stress that can be applied to rocks?
compression,tension,shear,and torsion stress
What are the types of deformation?
Elastic ad Plastic Deformation
What happens to the rock if elastic deformation occurs ?
soon as the stress is released it returns to its original shape
What happens to the rock if plastic deformation occurs?
Soon as stressed is released it will remain in a new shape
what types of seismic waves are there?
primary waves,secondary waves,surface waves
which type of seismic wave moves the fastest?
P-wave (primary)
What type of wave is a P-wave?
compression wave
How do primary waves move?
Compression wave
How to secondary waves move?
Transverse wave ( up and down)
What type of material can P-waves move through?
Solid and liquids
What types of material can S-waves move through?
ONLY solids
Which waves are the most complex?
Surface waves
What are the two scales that help us measure earthquakes?
Mercalli scale and the Richter scale
What does the Richter scale measure?
the amount of energy released
What does the Mercalli scale measure ?
the amount of damaged caused
