Today, deep waters formed in the northern North Atlantic fill approximately half of the deep ocean globally. In the process, this impacts on the circum-Atlantic climate, regional sea level, and soak up much of the excess atmospheric carbon dioxide from industrialisation — helping to moderate the effects of global warming.
Earth's crust was unstable in the Archean eon and dripped down into the mantle
Model calculations indicate that the extreme density of the base of the thickened primary crust caused it to subside into Earth's mantle.
A simple pendulum has two equilibrium points: hanging in the "down" position and perfectly inverted in the "up" position. While the "down" position is a stable equilibrium, the inverted position is definitely not stable. Any infinitesimal deviation from perfectly inverted is enough to cause the pendulum to eventually swing down.