GLG 141 Parks and Plates Pt. 3

old crust is

colder, more dense

rift zones on continents

continental crust is being thinned

as plates stretch and thin at rift zones

the underlying asthenosphere flows upward and expands, lifting the region to higher elevations

when continental crust breaks along faults

long mountain ridges are formed

east African rift

active rift

the red sea started as a rift but evolved into a

narrow ocean basin

continental - continental collides create

high mountains, no volcanism

why do continental continental collisions cause mountains

similar densities, light fluffy crust

oceanic continental subduction

oceanic plate will be pulled and sink into the asthenosphere

oceanic continental subduction leads to

volcanism due to melting of the subducted slab

oceanic oceanic subduction

the older colder slab will subduct

oceanic oceanic subduction creates

volcanoes and trenches

older colder oceanic slabs are

more dense

island arcs are formed from

oceanic oceanic subduction

transform faults on the ocean floor

connect and offset ridge segments

active faulting is indicated by

earthquakes

active faulting only occurs in

the part of the fracture zone between ridge axes

what causes plates to move

convection currents, ridge push and slab pull