Landslides in the Lower Greensand Escarpment of South Kent
In 1988, an area of landslides, known as The Roughs, situated on the Lower Greensand Escarpment, in the Wealden district of South Kent, started moving, after an extended period of stability. The Roughs had degraded to a low angled slope since being abandoned by the sea. This thesis undertakes to discover what triggered this reactivation, to clarify the mechanisms, magnitude and rate of the landslides and deduce the significance of the reactivation on other dormant landslides in the UK. The investigation was approached by the undertaking of a detailed desk study, a comprehensive series of fieldwork campaigns, and a statistical analysis of rainfall and a stability analysis of the slope. Although many investigations have been carried out in and around the research site, this thesis further contributes to the knowledge of the subject in the following ways. i Confirmation of detail in the geotechnics of land movement and how they relate to geological structure in the Lower Greensand Escarpment, Bilsington to Folkestone. ii. New geological sections through The Roughs. iii. Indications of the topographic; hydrological and other reasons for the exact location and extent of landslide activity in 1988 and later. iv. Qualitative discussion on the concept of cyclic variations in the factor of safety. v. Quantitative analysis of the effect of wet weather periods on The Roughs. vi. The use of both the infinite and the "finite" slope methods to analyse the stability of the degradation zone. vii. Examination of the effect of raised ground water levels on the stability of the site using other stability analysis methods. viii. An explanation of the sequence of events during the land movements. ix. New insights into the events at Stutfall Castle.