Past exam of the physics of the Earth as a Planet course of the University of Cambridge / 2013 / Paper 1 / 1 / a / ii

At the ridge axis, $T(z,0)=T_1$ for $0<z<a$ in the intended cooling model. Upwelling and magmatic heat supply continually bring hot material into the newly formed plate. The abrupt meeting of this hot interior with the cold upper boundary is an idealized corner discontinuity, resolved diffusively for $t>0$. The printed series fails this initial condition, as shown in the parent Solution.