What prevents complex molecules from spontaneously and rapidly degrading into atoms?

Bonding.

Explanation:

Bonding prevents complex or macro-molecules from spontaneously and rapidly degrading into atoms because force of attraction present between atoms. These bonds are very strong which is only breakable when there is high amount energy is supplied so we can conclude that bonding between atoms of complex molecules are responsible for their intact structure and prevent rapid degrading into atoms.

answer:

convection currents in the magma drive plate tectonics. heat generated from the radioactive decay of elements deep in the interior of the earth creates magma (molten rock) in the aesthenosphere. the aesthenosphere (70 ~ 250 km) is part of the mantle, the middle sphere of the earth that extends to 2900 km.