The geologic environment has a major influence on the likelihood, classification, and mechanisms of landsliding, the hydrogeology as it affects landsliding, and the strength of potential rupture surfaces in rock and soil. The geologic environment includes the type of rock (igneous, sedimentary, or metamorphic), stratigraphy, structure (bedding, folding, and faulting), defects (joints and sheared and crush zones), and weathering. The soils developed in these environments and their susceptibility to landsliding are related to the underlying rocks. Other factors that affect the likelihood, classification, and magnitude of landsliding include topography, climate, seismicity, and geologic history – for example whether the area has been glaciated.