Chapter 25 Flashcards
Mountain ranges on the sea floor separated by valleys.
Mid-Ocean Ridge (MOR)
Long narrow depression. Forms between peaks along MOR (Mid-Ocean Ridge)
Rift Valley
The boundary of which to plates collided.
Convergent Plate Boundary
Thick continental plate meets dense oceanic plate and the denser plate dives beneath the continent.
Subduction
The boundary between two plates moving apart.
Divergent Plate Boundary
The boundary of which two plate horizontally move past each other in opposite directions.
Transform Plate Boundary
The sudden movement or vibration of the ground when rocks slip/slide along one of Earth’s faults.
Earthquake
A crack in Earth’s crust where rock has moved.
Fault
The sudden release of strain energy as a rock moves along a fault.
Elastic Rebound
The point of origin for an earthquake.
Focus
The point on the Earth’s surface directly above the focus.
Epicenter
Who came up with the continental drift hypothesis?
Alfred Wegener
What evidence supported Alfred Wegener’s hypothesis?
- Coastlines match up like puzzle pieces.
- large land animal fossil were found.
- Mountain ranges match up and rocks have been found of the same composition and age.
What was the name of the supercontinent?
Pangea
Who came up with the sea spreading hypothesis.
Harry Hess
How did Harry Hess map the bottom of the sea floor?
Sonar
What system did Harry Hess discover?
Mid-Ocean Range (MOR)
Where is the youngest rock going to be found on the bottom of the sea floor?
Nearest to the MOR
What are the three types of plate boundaries?
- Divergent Boundary
- Convergent Boundary
- transfor Boundary
How do convergent plate boundaries move?
They collide
Subduction zones only occur with what type of plate boundary?
Convergent plate boundaries
How do divergent plate boundaries move?
They move apart.
What are two specific types of divergent plate boundaries?
The MOR and East African Rift
MOR- made up 2 of oceanic crusts
East African Rift- made up of only continental crust
How do plate transform boundaries move?
The slide alongside eachother in opposite directions.
What is a specific type of transform plate boundary?
San Andreas Fault
San Andreas Fault- made up of two continental crusts
How do convection currents work?
- Magma heats up, becomes less dense, and then rises.
2. The magma becomes less heated the farther away from the core and eventually falls back down to the core.
What are other forces that help plate movement?
- Slab pull- pulls down along subduction zone
- Ridge push- pushes plates apart along MOR
- Friction- Helps plates move
What land form is created when two continental crusts converge?
Mountains
What land form is created when two oceanic crusts converge?
Deep-sea trench and hot spots (creates islands)
what types of landforms are created when oceanic and continental crusts converge?
Deep-sea trenches and volcanoes
What types of crust are involved in plate moement?
Oceanic and Continental crusts
What type of plate boundaries have shallow earthquakes?
Divergent and Transform Plate Boundaries
70 km below the surface
Which plate boundary have deeper earthquakes?
Convergent Plate Boundaries
Deeper than 70 km
What are the four types of stress rocks can undergo?
Compression Stress (Pushed together) Tension Stress Pulling or tension of rock) Shear Stress (rubbing of two surfaces) Torsion Stress (twisting of surfaces)
What are the two types of deformation?
Elastic Deformation & Plastic Deformation
What happens to the rock when elastic deformation occurs?
As soon as the stress is released, it returns to its original shape.
What happens to a rock when plastic deformation occurs?
As soon as the stress is released it remains in itś new shape.
What types of seismic waves are there?
Primary Seismic Waves (P Waves)
Secondary Seismic Waves (S Waves)
Surface Seismic Waves
Where do seismic waves originate from?
They start from the focus.
Which type of seismic wave moves the fastest?
Primary (P) Wave
What type of wave is a Primary (P) Wave? How do they move?
Compression Wave. They move back and forth compressing and decompressing.
How do Secondary waves move? What types of waves are they?
They go up and down perpendicularly. Transverse waves.
What materials can Primary (P) waves move through?
Liquids and Solids
What materials can Secondary (S) waves move through?
Solids.
What are the most complex and dangerous type of seismic wave?
Surface waves (rolling motion causing trees and buildings to collapse.)
What two scales are used to measure earthquakes?
Richter Scale
Mercalli Scale
What does the Richter scale measure?
The amount of energy released.
What does the Mercalli scale measure?
The amount of damage caused.
