Furthermore, whereas resistant rock situated at this location had little
impact on the cliff toe position, the introduction of a weaker layer had
a significant effect on the cliff toe position and retreat rate (Fig. 9b).
For example, a fivefold increase in the resistant layer strength had negligible
influence on the equilibrium recession rate of the cliff toe
(Fig. 4b), whereas a fivefold decrease resulted in a 130% increase in
the recession rate by the end of the 5 ka simulation. However, a ‘lag’
in the influence of the weaker layer on the non-dimensional retreat
rate (N500 yrs) is apparent. This is attributed to the submerged position
of this layer and the subsequent time it takes the shore profile to adjust,
with progressively shallower shore profile slopes and lower cliff toes
with the presence of weaker material.