sustain (sustains 3rd person present) (sustaining present participle) (sustained past tense & past participle) 1 verb If you sustain something, you continue it or maintain it for a period of time. But he has sustained his fierce social conscience from young adulthood through old age... V n. ...a period of sustained economic growth throughout 1995.
If oceanic and continental crust collides the denser one which is the oceanic crust will be subducted, go underneath, the continental crust. The high heat of the mantle causes the oceanic crust to melt into magma. If the crust gets cracked this allows magma to rise and come out of the crust as lava which will form Volcanoes. When two continental crusts collide, the crust is forced to go upwards which forms mountains.
Convergent Boundaries. Oceanic crust becomes cooler and denser as it spreads away from the mid-ocean ridge. Where two plates carrying oceanic crust meet at a trench, the plate that is more dense sinks under the other plate. Sometimes a plate carrying oceanic crust collides with a plate carrying continental crust. Oceanic crust is more dense than continental crust. The less dense continental crust canât sink under the more dense oceanic crust. Instead, subduction occurs as the oceanic plate sinks beneath the continental plate. When two plates carrying continental crust collide, subduction does not take place. Neither piece of crust is dense enough to sink very far into the mantle. Instead, the collision squeezes the crust into mighty mountain ranges.