The layer of the earth where mantle convection occurs and on which the earth's crust rests is the

The asthenosphere is the highly viscous mechanically weak ductility-deforming region of the upper mantle of the Earth. It lies below the lithosphere, at depths between 100 and 200 km (~62 and 124 miles) below the surface, but perhaps extending as deep as 700 km (~435 miles).

The asthenosphere is a portion of the upper mantle just below the lithosphere that is involve in plate tectonic movements and isostatic adjustments. In spite of its heat, pressures keep it plastic.

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In the passage this question was provided for, you should have been able to locate the fallowing text: "the outer layer of the mantle; made up of plastic or semi-molten rock" and many others to imply this answer.

Asthenosphere

answer; i believe its echoic memory,it is believed to last three to four seconds; good luck