Plate Tectonics Flashcards
composed primarily of a nickel-iron alloy
solid inner core
2 300 km thick
composed of a nickel-iron alloy (but with less iron)
outer core
very hot that the metals are in liquid state
outer core
2 900 km thick
mantle
compromises 70% of Earth’s volume
mantle
outer silica-rich, solid crust, highly viscous
mantle
outermost layer of the Earth
crust
two types of crust
continental
oceanic
thick (10-70 km)
buoyant (less dense)
contains some of the oldest rocks on Earth
continental crust
thin (-7 km)
dense
oceanic crust
what happens when the two types of crust meet?
oceanic crust will sink underneath continental crust
deformation of the crust as a consequence of plate interaction
tectonic
fill in the blanks: Each type of plate interaction causes a ————- set of —— structures or “————” features
characteristic, Earth, tectonic
fill in the blanks: The Earth’s crust is divided into – major ——, moving in various directions
12, plates
fill in the blanks: Plates are made of rigid ————–
lithosphere
What makes up the lithosphere?
crust and upper mantle
asthenosphere
below the lithosphere which makes up the tectonic plates
how do plates move?
lithospheric plates are moved around by the underlying hot mantle convection cells
fill in the blanks: in the ——–, hot ——— rises towards the lithosphere
mantle, material
fill in the blanks: Hot material reaches the base of the ———— where it cools and —- back down through the mantle
lithosphere, sinks
fill in the blanks: The —– material is replaced by more hot material forming a large ————- cell
cool, convection
fill in the blanks: This —- but incessant movement in the ——- causes the rigid tectonic plates to move (float) around the Earth’s surface
slow, mantle
what happens when plates meet?
they form plate boundaries
types of plate boundaries
divergent
convergent
transform
‘spreading ridges’
divergent
as plates move apart, new material is erupted to fill the gap
divergent
example of continental rifting
Iceland
fill in the blanks: Iceland has a ———– plate boundary running through its middle
divergent
plates move towards each other
convergent
fill in the blanks: The three styles of convergent plate boundaries are defined by what type of —— is coming together
crust
styles of convergent plate boundaries
continent-continent collision
continent-oceanic crust collision
oceanic-oceanic plate collision
forms mountains
i.e. Himalayas, Sierra Madre Mountain Range
continent-continent collision
how are mountains formed?
continental crust pushes against continental crust
neither side of the boundary wants to sink beneath the other side
plates push against each other
crust buckles and cracks pushing up high mountain ranges
subduction occurs
continent-oceanic crust collision
primarily solid sphere about 1 220 km situated at Earth’s center
solid inner core
where continental crust pushes against oceanic crust and sinks it below the continental crust because of its density
subduction zone
oceanic crust which descends into the mantle at a rate of centimeters per year
subducting slab
fill in the blanks: When the subducting slab reaches a —— of around 100 km, it dehydrates and ———– water into the overlying ——- wedge
depth, releases, mantle
fill in the blanks: The addition of —– into the mantle wedge changes the melting point of the molten material forming new —— material which rises up into the overlying continental crust forming ———-
water, molten, volcanoes
fill in the blanks: The world’s deepest parts of the ocean are found along ——–
trenches
trench
very deep depression in the ocean floor formed by a bent subducting plate
fill in the blanks: When two ——- plates collide, one runs over the other which causes it to sink into the ——– forming a ———– —-
oceanic, mantle, subduction zone
where plates slide past each other
transform plate boundaries
How are volcanoes formed?
via subduction
via rifting
form at “Hotspots”
True or False: Hotspots do not necessarily occur along a plate boundary
True
hotspot volcanoes
can form in the middle of tectonic plates
hot mantle plumes breaching the surface in the middle of a tectonic plate
i.e. Hawaiian island chain
hotspot volcanoes
fill in the blanks: As with volcanoes, ————– are — randomly distributed over the globe
earthquakes, not
fill in the blanks: At plate boundaries, —— causes them to stick together. ————- occur when built up —– causes them to break
friction, earthquakes, energy
Earthquakes are NOT randomly distributed around the globe. Why?
They occur in linear patterns associated with plate boundaries.
shaking of the ground caused by sudden motions along faults or fractures in the Earth’s crust
earthquake
fracture in the rocks that make up Earth’s crust
fault
massive rocks that make up the outer layer of the Earth’s surface
plates
movement along faults triggers earthquakes
plates
point within the earth where an earthquake rupture starts
focus
hypocenter
focus
point at the Earth’s surface directly above the focus
epicenter
waves that transmit the energy released by an earthquake
seismic waves
