The failure mechanism of the 1839 Bindon Landslide, Devon, UK : almost right first time

The Axmouth to Lyme Regis Undercliffs National Nature Reserve in east Devon includes the most famous mass-movement feature in Britain, the Bindon Landslide of Christmas Day 1839. Tens of millions of tonnes of rock, older landslide debris and beach deposits were pushed forward when a large mass of Cretaceous rocks became detached from the 120 m-high cliffs and slid seaward. Fissures appeared in the cliff top on the 23rd December and culminated in the main movement during the night of the 25-26th December. The event attracted large numbers of sightseers from all over southern England. Fortunately for geology, these included the pioneer geologists the reverends William Buckland and William Conybeare who lived in the area, and a local surveyor William Dawson. They, together with Buckland’s artistically gifted wife Mary, produced detailed geological descriptions, plans, views and sections of the landslide within a few weeks of its occurrence. Their published account is commonly quoted as the first detailed description of the mechanism of a large landslide. Later authors have queried their conclusions, but none of these accounts paid such detailed attention to the role of the geology in the failure mechanism. Recent geological surveys have confirmed that the description by the Bucklands, Conybeare and Dawson is an outstanding example of observation and analysis, and that their interpretation of the mechanism, although incomplete, was superior to that of any subsequent account. Recently available aerial photographic and multibeam-sonar data has shown that an important factor missing from all previous interpretations are faults that run beneath and subparallel to the structures in the landslide.