Chapter 25 Flashcards
System of mountain ranges on the seafloor separated by valleys.
Mid-Ocean Ridge
A long, narrow depression that forms in between peals 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
Two plates move apart along a mid-ocean ridge.
Divergent Plate 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 the Earth’s crust called faults.
Earthquake
A crack in Earth’s crust along which rock has moved.
Fault
The sudden release of strain energy as rocks 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 supported his hypothesis?
- The coastlines matched up like puzzle pieces
- He looked at large land animal fossils, which matched up with different types of animals from the different continents
- Mountain ranges matched up, which had similar rock composition and age
What was the name of the supercontinent?
Pangaea
Who came up with the seafloor spreading hypothesis?
Harry Hess
How did Harry Hess come up with his hypothesis?
He used sonar
Who discovered the mid-ocean ridge?
Harry Hess
Where will younger rock be created on the seafloor?
Near the MOR
What are the types of plate boundaries?
- Convergent Plate Boundaries
- Divergent Plate Boundaries
- Transform Plate Boundaries
What are the two types of crusts that deal with plate boundary movement?
- Oceanic Crust
2. Continental Crust
How do convergent plates move?
They collide/come together
What types of land forms can form when convergent plates collide?
Deep-sea trenches
Subduction only happens with what type of plate boundary?
Convergent Plate Boundaries
What type of land-forms can be created when two oceanic crusts collide?
- Deep sea trenches
2. Hot spots, which create islands
What type of land forms can be created when two continental crusts come together?
Mountains
What type of crust must be present for volcanic activity to occur?
Oceanic crust must be present
How do divergent plates move?
They move away from each other; divide; separate
What are specific examples of divergent plate boundaries?
- A MOR (Mid-Ocean Ridge [both are oceanic crusts])
2. The East African Rift (both are continental crusts)
How deep, long, and wide is the East African Rift?
3 miles deep, 4.000 miles long, and 30-40 miles wide
How do transform plate boundaries move?
They slide past each other horizontally
How do transform plate boundaries move?
They slide past each other horizontally
What is a specific example of a transform plate boundary?
The San Andreas Fault
What types of crusts are involved in transform plate boundaries?
Both are continental crusts
How do convection currents work?
- Magma heats up, becomes less dense, and rises
2. Magma cools down, becomes more dense, and seeps back into the ground near the core of Earth
What are other forces to help plate motion?
Slab pulls, ridge pushes, and friction
Which plate boundaries have shallow earthquakes?
Divergent and transform
Which plate boundary has deep earthquakes?
Convergent
What types of stress can be applied to rocks to cause movement?
Compression stress, tension stress, shear stress, and torsion stress
What are the types of deformation that can be caused due to stress?
Elastic and plastic deformation
What happens when elastic deformation occurs?
It deforms and then returns back to its original shape.
What happens when plastic deformation occurs?
It deforms and remains in its new shape/deformation
How many types of seismic waves are there?
There are three: Primary waves, secondary waves, and surface waves.
Which waves are the fastest?
P-waves
What type of wave of is a P-wave?
A compression wave
What type of material can P-waves travel through?
Solids and liquids
What type of wave are secondary waves?
Transverse waves
What type of material can S-waves travel through?
Only solids
Which wave is more complex and causes the most damage?
Surface waves
What are the names of the two scales that help measure earthquakes?
Richter Scale and Mercalli Scale
What does the Richer Scale measure about an earthquake?
The amount of energy released
What does the Mercalli’s Scale tell about earthquakes?
How much damage is caused
