Chapter 12.2 Features of Plate Tectonics Flashcards
what is the top layer of the earth called?
The crust, which is made out of elements of oxygen, silicon which form to make groups of rocks called silicates
What are the 5 layers of the earth called? (order from exterior to interior)
crust, upper mantle, lower mantle, outer core, inner core
what does the lithosphere include?
crust, uppermost mantle, tectonic plates
65 - 100 km thick
what is the asthenosphere?
below lithosphere, partially liquid in upper mantle
temp varies because of large quantities of radioactive elements such as uranium in some areas
explain mantle convection
radioactive decay heats up mantle
heated particles have more kinetic energy, move around more, spreading farther apart
convection current in the asthenosphere happens when the hotter, less dense material rises, cools, then sinks again, the cycle starts over
what happens if a spreading centre occurs in the ocean?
it will create an oceanic ridge or a trench
what happens if a spreading centre occurs on land?
it will create a rift valley
what is ridge push?
when new material arises from the asthenosphere and pushes older material aside, tectonic plates move away from the ridge
what is subduction?
the action of one plate pushing below another
a dense oceanic plate sub-ducting under a less dense continental plate
what are subduction zones?
areas of subduction that experience large earthquakes and volcanic eruptions
what is slab pull?
when a tectonic plate subducts deep into the mantle, pulling the rest of the plate with it
what is a plate boundary?
a region where 2 tectonic plates are in contact
what are the 3 types of plate interaction?
divergence (spreading apart), convergence (moving together) and transform (sliding by)
depends on the type of plate and direction the plates are moving
what are divergent plate boundaries?
areas where tectonic plated are spreading apart
what are diverging plates? give an example
plates that are spreading apart
the mid atlantic ridge spreading ridges that separate, americas from africa, europe and asia
what is a converging plate boundary?
where tectonic plates collide
what are converging plates?
plates that collide
what happens during ocean-continental plate convergence?
oceanic plate subducts under continental plate, creates a deep underwater valley called a trench
subducting plate melts as it goes deeper, cools and crystallizes into large rock masses below continental plate surface
could make cone shapes volcanoes if the magma works itself up to the surface (ex. Juan de fuca plate (oceanic) and north american plate (continental) has a long chain of volcanoes
the force of collision between the oceanic/continental plate could create mountain ranges due to the folding and crumpling of the continental plate (ex. BC’s coast mountains)
earthquake results in pressure building up due to the resistance in convection currents, ridge push and slab pull and releases pressure
what happens during oceanic-oceanic plate convergence?
when a denser oceanic plate subducts under a less dense oceanic plate
may produce a long chain of volcanic islands called a volcanic island arc
ex. islands of japan and indonesia
what happens during continental-continental plate convergence?
subduction does not occur because plates’ similar densities prevents one from going under the other
creates massive mountain ranges
ex. Himalayas
what are transform plate boundaries?
when convection currents in the mantle cause tectonic plates to slide past each other
what are faults?
breaks in rock layers due to movement on either side
what is a transform fault?
a fault that occurs at a transform plate boundary
ex. Andreas fault of california in us
What is an earthquake?
when tectonic plates release energy from pressure building up
