Past exam of the year 2 of the earth sciences (geology) course of the University of Oxford / 2023 / Paper 1 / 6 / d / Solution

For a horizontal interface, Snell law for elastic waves conserves horizontal seismic ray parameter $p=\sin i/V$. At the limestone–sandstone interface the incident P wave has $p=\sin 20^{\circ }/2500$. The reflected S wave remains in the limestone, sofrom vertical. All angles below use this normal-to-interface convention.