CH 25 Flashcards
Mid-Ocean ridge
A system of mountain ranges on the seafloor separated by valleys.
Rift Valley
A long, narrow depression.
Convergent Plate Boundary
The boundary where two plates collide.
Subduction
A process where when a thick and buoyant continental plate meets a thin and dense oceanic plate, the denser plate dives beneath the continent.
Divergent Plate Boundary
The boundary between two plates that are moving apart.
Transform Plate Boundary
A type of boundary where plates slide horizontally past each other in opposite directions.
Earthquake
The sudden movement or vibration of the ground that occurs when rocks slip and slide along enormous cracks in Earth’s crust called faults.
Fault
A crack in Earth’s crust along which rock has moved.
Elastic Rebound
A sudden release of strain energy as rock moves along a fault.
Focus
The point of origin for an earthquake.
Epicenter
The point on Earth’s surface directly above the focus.
Who came up with the continental drift hypothesis?
Alfred Wegener
What were some pieces of evidence that supported Alfred’s hypothesis?
- Large land animal fossils
- Coastlines fit together like puzzle pieces
- Mountain ranges line up and have the same rock composition
What was the name of the super continent?
Pangaea
Who came up with the Seafloor Spreading Hypothesis?
Harry Hess
What did Hess use to help him create a map of the seafloor?
Sonar
Who discovered the mid-ocean ridge?
Harry Hess
Where will younger rock be located?
Near the MOR
What are the three types of plate boundaries?
- Divergent
- Convergent
- Transform
Subduction only happens with what kind of plate boundary?
Convergent
What are the two types of crust that are involved in plate boundary movement?
- Oceanic
2. Continental
What land forms can form when oceanic crust and continental crust converge?
- Volcano
2. Deep-sea trench
What land forms can be created when two oceanic crusts collide?
- Hot spots=they create islands
2. Deep-sea trench
What land form is created when two continental crusts converge?
Mountains
What type of crust must be present for volcanic activity to occur?
Oceanic crust
How do divergent plate boundaries move?
They move in opposite directions.
What are two examples of divergent plate boundaries?
- Mid ocean ridge (made up of oceanic crust)
2. East African Rift (made up of two continental crusts)
How do transform plate boundaries move?
They slide by eachother.
What is a specific example of a transform plate boundary?
San Andreas Fault. (Two continental crusts
How do convection currents work?
- Magma heats up, becomes less dense, then rises.
2. Magma cools down, becomes more dense, then sinks.
What are the other forces that help with plate movement?
- Slab pull
- Ridge push
- Friction between plates and the mantle
What two types of boundaries have shallow earthquakes?
- Divergent
2. Transform
Which type of plate boundary has deep earthquakes?
What are the types of stresses that can be applied to rock?
- compression
- tension
- shear
- torsion
What are the two types of deformation?
- Elastic
2. plastic
What happens to a rock during elastic deformation?
it deforms and returns to its original shape.
What happens to a rock during plastic deformation?
It deforms and stays in that same shape.
What are the kinds of seismic waves?
- Secondary
2. Surface
Which type of seismic wave moves the fastest?
Primary
How do primary waves move?
They are compression waves
What type of materials do P-waves move through?
Solids and liquids
How do secondary waves move?
They are transverse waves.
What type of materials do secondary waves move through?
Solids
Which type of wave is the most complex and does the most damage?
Surface waves
What are the two scales used to measure earthquakes?
- Richter
2. Mercalli
What does the Richter scale tell us about n earthquake?
The amount of energy released.
What does the Mercalli scale tell us about an earthquake?
The amount of damage it causes.
