Chapter 25 Flashcards
System of mountain ranges on the seafloor separated by valleys
Mid-ocean ridge
A long, narrow depression
Rift Valley
Boundary where two plates collide
Convergent Plate Boundary
Process when a thick and buoyant continental plate meets a thin and dense oceanic plate, the denser plate beneath the continent
Subduction
Boundary between two plates that are moving apart
Divergent Plate boundary
Type of 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 Earth’s crust called faults
Earthquake
A crack in Earth’s crust along which rock has moved
Fault
Sudden release of strain energy as rock moves along a fault
Elastic Rebound
Point of origin for an earthquake
Focus
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
- They found large land animal fossils
- Mountain ranges match up, and the rocks are made up of the same composition and same range
What was the name of the super continent before it broke up?
Pangaea
Who came up with the Seafloor Spreading Hypothesis?
Harry Hess
How did he map the bottom of the seafloor?
Sonar
Who discovered the mid-ocean ridge system, (MOR)?
Harry Hess
Where is the youngest rock found on the bottom of the seafloor?
Mid-ocean ridge (MOR)
What are the types of plate boundaries?
Divergent, Convergent, and Transform
How do Convergent Plate Boundaries move?
They 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 trenches and volcanoes
What land forms are created when two oceanic crust converge?
Deep-sea trench and hot spots (creates islands)
What land form is created when two Continental crusts converge?
Mountains
How do Divergent Plate Boundaries move?
Move away from each other
What are two specific examples of Divergent Plate Boundaries?
Mid-Ocean Ridge (MOR oceanic crust only) and East African Rift (Only continental crust)
How do Transform Plate Boundaries move?
They slide by each other (Horizontally)
What is a specific example of a Transform Boundary Plate?
San Andreas Fault (two continental crusts)
How does a Convection Current work?
- Magma heats up, becomes less dense, and rises
2. Magma cools down, becomes more dense, and sinks
What are other forces that help plate movement?
A Slab Pull, a Ridge Push, and Friction
What types of plate boundaries have shallow earthquakes?
Divergent and Transform Plate Boundaries
Which boundary has deep earthquakes?
Convergent Plate Boundaries
What are the four types of stress that can be applied to rocks?
Compression (pushed together), Tension (being pulled), Shear (surfaces rubbing along), and Torsion Stress (twist)
What the two types of deformation?
Elastic Deformation and Plastic Deformation
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 will remain in the new shape.
What types of seismic waves are there?
Primary Waves (P waves), Secondary Waves (S waves), and Surface Waves
Which type of seismic wave moves the fastest?
Primary Wave (P-Wave)
How do Primary Waves(P-Waves) move?
A Compression Wave
How do Secondary Waves move?
A transverse wave (up and down)
What types of materials can P-Waves move through?
Liquids and Solids
What type of material can S-Waves move through?
Solids (only)
Which waves are the most complex and dangerous?
Surface Waves
What are the two scales that help us measure earthquakes?
Mercalli Scale and Richter Scale
What does the Richter Scale measure?
The amount of energy released
What does the Mercalli Scale measure?
How much damage was caused by the earthquake.
