Oceanic thermal subsidence
= Oceanic thermal subsidence
{title2=$d(t)-d_r\propto\sqrt t$}
Cooling oceanic <lithosphere> contracts and increases its column <mass>, causing isostatic deepening. Integrating a half-space cooling profile gives an excess <mass> proportional to $\sqrt t$. Converting this to seafloor depth includes the <density contrast> between <mantle> and seawater. Finite-plate cooling and basal <heat> supply limit indefinite square-root subsidence at old ages.