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Topographic Wetness Index (TWI) and Terrain Ruggedness Index (TRI) are secondary geomorphometric parameters used to describe and quantify local relief. In this paper their usefulness in geomorphological studies of landslides is explored. Using a sample of twelve objects from the Sudetes, SW Poland, spatial and statistical distributions of TWI and TRI values are presented and discussed. Both TWI and TRI prove capable of differentiating landslide population into smaller groups, consistent with their variable origin and mechanism of displacement. Considerable disruption of original slope surface during movement results in high TWI range values and low TRI values, whereas for translational rockslides and slumps the relationship is opposite. Spatial patterns of high TWI values help to identify lines of preferential drainage of a landslide body. Directional analysis shows that different types of displacement have their specific morphological signatures. Both TWI and TRI provide new information about landslide morphology and are recommended for use, especially to characterize depositional parts of landslides. The study is based on high resolution digital elevation model derived from airborne laser scanning (LiDAR) which proved useful in detailed characterization of landslide morphology.

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Mesas are residual landforms typical for layered rock sequences, formed due to tableland dissection and cliff retreat. Caprock cliffs are characteristic elements of mesa morphology. Mesas have finite lifetimes and over time are reduced in area, transforming into buttes and eventually into irregular arrays of boulders. Thus, they are ‘born’, when separated from a plateau, and ‘die’, when the caprock completely disintegrates. In this paper, sequential development of sandstone-capped mesas is first inferred from theory and then verified on the basis of field observations and landform inventories from a sandstone tableland of the Elbe Sandstone Mountains in the eastern part of Germany. Finally, selected morphometric parameters of mesa morphology, potentially indicative of their evolutionary phases, are computed from a high-resolution digital terrain model. Both field evidence and results of morphometric analysis indicate that mesas evolve along various pathways and, tending towards specific end-members, illustrate the principle of equifinality. Space-for-time substitution, if applied with care, may also be helpful in deciphering the geomorphic history of mesas and tracing their life until disappearance.