The soil body is formed by a layered profile. An arbitrary number of layers can be used. Each layer is defined by its geometry and material. The material of a layer is usually represented by soil with specified properties, where shear strength is described using Mohr-Coulomb or Hoek-Brown criterium. The geostatic stress in the soil body is determined during the analysis.
A layer can be specified also as a rigid body. Such a layer then represents bedrock or a sheeting wall. The slip surface can never pass through the rigid body.