Chapter 25 Flashcards
A system of mountain ranges on the seafloor separated by valleys
Mid-ocean ridge
A long, narrow depression
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
The boundary between two plates that are moving apart
Divergent plate boundary
A 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
A fault
The sudden release of strain energy as rock 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 continent drift theory? (hypothesis)
Alfred Wegener
large land animal fossils
mountain ranges matched up with same rock time and ages
closeline matched up
What was the name of the supercontinent?
Pangaea
Who came up with the seafloor spreading hypothesis?
Harry Hess
How did Harry Hess discovered the mid-ocean ridge?
Sonar
Who discovered the MOR?
Harry Hess
What are the types of plate boundaries?
Divergent boundary
convergent boundary
transform boundary
How do convergent plate boundaries move?
Together
Subduction zones occur with which type of plate boundary
a convergent plate boundary
What two types of crust can be used with plate boundaries?
Oceanic crust and continental crust
Volcanos
What type of crust must be present for volcanic activity to occur
oceanic
How do divergent plate boundaries move?
They move away from eachother
What are some examples of divergent plate boundaries?
- MOR (both oceanic crust)
2. East African Rift (made of two continential crusts)
How do transform plate boundaries move?
They slide past each other
What is a specific example of a transform plate boundary?
San Andreas Fault (continential crust)
What is a convection current?
- Magma heats up, becomes less dense, and rises
2. Magma cools down, becomes more dense, and sinks
What are three forces that contribute to plate motion
Slab pull
ridge push
friction
Which plate boundaries have shallow earthquakes?
Divergent and transform
Which plate boundary has deep earthquakes?
convergent
What are the types of stress that can act upon rocks to cause movement?
Compression stress
a tension stress
a shear stress
torsion stress
What are the two types of deformation?
Elastic
Plastic
What happens to the rock when elastic deformation happens?
The material goes back to its original shape
What happens to the rock when plastic deformation happens?
The rock takes on a new shape
How many types of seismic waves are there?
Primary waves
secondary waves
surface waves
What type of seismic wave is the fastest?
primary wave
What type of wave is a primary wave?
compression wave
What type of materials can soundwaves pass through?
solids and liquids
what type of wave is a secondary wave
transverse
What types of material can s waves pass through?
only solids
Which wave does the most damage?
surface wave
What are the two scales that measure earthquakes
Richter magnitude
mercalli scale
what does the richter scale measure
the amount of energy
define rock
a rock is a naturally formed mixture containing minerals, rock fragments, and volcanic glass
how are rocks identified
by composition and textured
what does the texture of a rock describe about a rock
the shape, size, and arrangement of the rock’s components
where do intrusive igneous rocks form
within the earths crust
what type of molten rock does intrusive igneous rocks form from?
magma
what is the name of the series that illustrates simultaneous crystallization of silicate minerals
bowen’s reactions series
what are the three types of magma
matic, intermediate, fedsic
which magma type has a low silica content
maphic
which magma type has a high silica content
felsic
which type of crust has an abundant amount of quarts
continental
which type of crust had little to no quarts
oceanic crust and deep continetal
which type of
rocks are identified by their composition
do fine grained rocks cool slowly or quickly?
what are the two texture types of igneous rocks?
vesicular and porphyitical
which rock has holes in it
vesicular
which texture is the type of two different cooling rate
phorphoritic
rock
pumice
