The contrasting effect of stronger/weaker layers on shore profile
slope and cliff toe elevation can also explain the differing boundary elevations for which such layers were found to influence rates of cliff toe
retreat. The outcropping of lithologies in relation to MSL is paramount
(−1 to +3 m for a more resistant layer and −2 to +2 m for a weaker
layer). However, this range may well vary depending on the prevailing
coastal conditions used. The findings are supported by the simulations
of the effects of sea-level rise; multiple layers of variable rock strength
in the cliff face only influence the profile shape and rate of cliff toe retreat
when encountered by MSL.