The erosion process is natural weathering, wave action undercutting the mudstone until eventually the top bit falls. Its made worse by removal of native vegetation and earthworks which alters the drainage and water table. These heavy rains saturate the ground and weight tends to makes the strata slide on top of each other, if you've ever been to any of the gold mining sites and seen the power of sluicing where they used to literally demolish hillsides, its obvious you really need to have good drains on a cliff site! Whats surprising about the guy who lost his swimming pool (and his house has