Chapter 25 Flashcards
mid-ocean ridge
a system of mountain ranges on the seafloor separated by valleys
rift valley
long narrow depression
convergent plate boundary
boundary where tow plates collide
subduction
a thick and buoyant continental plate meeta a thin and dense oceanic plate, the denser plate dives beneath the conitent
divergent plate boundary
the boundary between two plates that are moving apart
transform plate boundary
boundary where plates slide horizontally past each other in opposite directions
earthquake
a sudden movement or vibration of the ground that occurs when rocks slip and slide along enormous cracks in earth crust
fault
crack in earth’s crust
elastic rebound
sudden release of strain energy as rocks move along a fault
focus
point of origin for an earthquake
epicenter
points on earth’s surface above a 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 matched up like puzzle pieces
- moutain ranges matched up and fitted together with same rock compostion and same age.
What was the name of the super continent?
Pangaea
Who came up with the seafloor spreading hypothesis?
Harry Hess
What did Harry use to create a 3d map of the seafloor?
Sonar
Who discovered the mid ocean ridge?
Harry Hess
Where is younger basalt found on the bottom of the seafloor?
Near the Mor(mid ocean ridge)
What are the three types of plate boundaries?
Diversion boundary
Transform boundary
Convergent boundary
What plates can subducation happen with?
Convergent plates
What is subduction?
The more dense plate goes under 5he less dense plate.
What are the two types of crust that are involved into plate boundary movement?
Continental crust
Oceanic crust
Whaat landforms can form when oceanic and continental plate converge?
Deep sea trenches
Volcanoes
What land forms can form from when two oceanic crusts collide?
Hotspots that create islands
Deep sea trench
Wwhat landforms are created when two continental crusts converge?
Mountains
What type of crust must be present active for volcanic activity?
Oceanic crust
What type of crust must be present for volcanic activity?
Oceanic crust
How do divergent plates moves?
The plates move away.
What are two examples of divergent boundaries?
Mor(made up of oceanic crust)
East African Rift (made up of two continental crusts)
How do transform plates move?
Slide horizontally by each other.
What is a specific example of a transform boundary?
San Andreas Fault
What types of crust is involved with transform boundary?
Two continental crusts.
What is a convection current.
Magma heats up becomes less dense, then rises.
Magma cools down becomes more dense then sinks.
What are the other forces that help with plate movement?
Slab pull
Ridge push
Friction
How deep are earthquakes that happen along divergent,transform, and covergent plate boundaries?
Divergent-less 70km
Transform-less 70km
Convergent-70km or more
What are the four types of stress?
Compression
Torsion
Tension
Shear stress
What are the two types of deformation?
Elastic deformation
Plastic deformation
What happens to a rock during elastic deformation?
The rock goes back to it regular shape after stress is relieved.
What happens to a rock in plastic deformation?
The rock stays in the shape the stress configured it in after the stress is relieved.
What are the kinds of seismic waves?
Primary waves
Secondary waves
Surface waves
What is another name for primary eave?
waves? Waves
What are the fastest waves?
Primary waves.
How do primary waves move?
Compression waves
What do pwaves move through?
Solids and liquids
How do Secondary waves move?
Transverse waves
What type of materials do s waves move through?
Solids
What waves cause the most damage and are the most complex?
Surface waves
What are the two scales to measure earthquakes?
Richter scale
Mercalli
What does the Richter scale measure?
Measures the earthquakes’ energy released.
What does the mercalli scale tell about an earthquake?
The amount of damage done.
