types of plate margins Flashcards
(12 cards)
what is a constructive plate margin?
- two plates move apart
how is a ocean ridge formed?
-diverging plates underwater, seafloor spreading
- as tectonic plates diverge, magma rises to fill the gaps then cools to form new crust
- overtime new crust is dragged apart and new crust forms inbetween
how is a rift valley formed?
-where plates diverge beneath land, rising magma causes continental crust to bulge and fracture causing fault lines
-as plates keep moving apart the crust between parallel faults drops down to forma rift valley
what is a destructive plate margin
- plates are moving towards each other
what forms near oceanic-continentalplates?
fold mountains, deep sea trenches, volcanoes, earthquakes
how are deep sea trenches formed?
-when continental crust and oceanic crust converge, dense oceanic plate is forced under the less dense continental plate
this forms a deep trench in the sea
what forms on a oceanic-oceanic margin
-denser of thw two will subduct forms a deep sea trench, triggering earthquakes and volcanic eruptions
- volcanic eruptions that occur underwater create island arcs
what occurs on continental-continental plates?
- 2 plates of continental plate moves tpwards each other , neither is subducted but pressure that builds up causes earthquakes
- fold mountains are also created
where do conservative plate margins occur
-2 plates moving pats each other
what occurs at conservative plate margins
-earthquakes,plates lock together, pressure craeted plates jerk past eavh other, energy released as eartgquake
where do most volcanic eruptions occur
near contructive and destructive plat emargins
