EARTHSC 1121 Lecture 11: 2/16
23 Mar 2017
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Tophat q: on the surface of the earth, deformation occurs primarily where one plates meets another. Linear mountain ranges in earth"s ocean basins. These linear mountains are formed by divergence. Snakes n-s through the entire atlantic ocean (sa & africa, na & europe). Elevated ridge (1,500 km wide) 2 km above abyssal plains (stands above the. Axial rift valley. average depth of the ocean). Slope on one side tends to look like the slope on the other. This is oddly paradoxic--the mantle is not magma, yet magma fills in the gap of a mid-ocean ridge. Sea-floor spreading opens the axial rift valley. Rising asthenosphere melts, forming mafic magma (magma that is formed from mantle. Pooled magma solidifies into oceanic crustal rock. material; mafic = high magnesium and iron rock. Where cracks have opened up in the crust, filled with magma, then frozen in place. The hot asthenosphere is at the base of the mor.
