Scarpland formation produced low-inclined slopes susceptible to deep-seated landsliding on geological scales. These landslide-affected slopes are often used for forestry activities today, and interaction between geology and vegetation controls shallow landsliding. Our data show that Feuerletten clays control deep-seated landsliding processes that can be reactivated. When trees are sufficiently dense to provide lateral root cohesion, trees can prevent the occurrence of shallow landslides.