This study investigated the deformation characteristics of consequent slate slopes in the region between Cuifeng and Wuling in Taiwan. Onsite survey and UDEC numerical models were used to describe the characteristics of gravity-driven deformation under various conditions and identify the process of slate deformation as well as potential failure mechanisms. Our results demonstrate that valley erosion and slope toe soaking mechanisms play key roles in the deformation of slate and accelerate the weakening of slate material. Slate deformation was shown to begin in the tension zone at the cliff top, wherein the slope body slips along the highly inclined foliation, contributing to shear failure or composite failure near the eroded zone of weakness. The phenomenon of foliation opening was widespread within the area of deformation, enabling surface water and groundwater to seep in, thereby accelerating failure in the slate deformation zone.