Constant-temperature lava-crust growth law
= Constant-temperature lava-crust growth law
{title2=$SR^2\tau=-Rh-\log(1-Rh)$}
In the <radiogenically heated lava-lake crust model>, <temperature> stays constant precisely when $\theta_0=R/B$. Then $h'=S(1/h-R)$, and an initially absent crust satisfies the displayed law for $0\le h<1/R$. It follows by integrating $h/(1-Rh)$ from zero to $h$. The crust starts as $\sqrt{2S\tau}$ and tends to $1/R$ only at infinite time. The equilibrium remains thin only if $R\gg1$.