This study investigates the deformation characteristics of consequent slopes in central Taiwan prior to sliding failure. Field surveys, terrain analysis, and physical model tests were performed to explain the gravitational deformation characteristics of consequent slopes under various conditions and to derive the deformation process and failure characteristics. The results thus obtained that distribution of erosion and material weakening mechanisms in gullies are crucial to the deformed process of consequent slopes. Consideration of various conditions, including foliation dip angle, sliding mass geometry, and spacing between foliation planes, indicate that increasing the foliation dip angle and the thickness of sliding mass increases the depth of slope deformation. Foliation dip angle is the most critical factor that controls the deformation of slate, slope length has a weaker effect. Deformation initially began in the tension zone at the top of the slope. The slope body moved gradually along a weak plane at a specific depth and bulged at the slope toe, causing shearing damage nearby. The deformation zone exhibited significant cracking, which facilitated the infiltration of surface water and groundwater, accelerating the deformation, which leads ultimately to failure.