Evidence for subsurface origin of boulder caves, roofed slots and boulder-filled canyons (Broumov Highland, Czechia)

The backslope of a sandstone cuesta in the Broumov Highland (Czechia) is cut by a complex network of canyons. Long sections of canyons have thick boulder fills which are difficult to reconcile with simple rock fall and talus development scenario. Boulder caves occur within these fills and their lowermost parts are drained by streams that evacuate fine loose sandy material produced by weathering and mechanical erosion. These boulder fills are explained as largely in situ, residual features, left after subsurface selective disintegration of rock mass, mainly joint-guided, and removal of grains by underground water. Evacuation of fines leaves voids into which overlying blocks subside but the voids may be spacious enough (largely because the rock blocks are so large) to connect into penetrable caves. Results of an analogous process may be observed along canyon walls where more densely jointed sandstone compartments develop into roofed slots. Additional evidence for an important role of subsurface processes is provided by closed depressions in the inter-canyon areas. A model of canyon evolution is offered, alternative to the existing models implying surface fluvial erosion or retreat due to spring sapping. Its applicability is limited by the thickness of a sandstone package but the origin of canyons a few tens of metres deep (up to 100 m or so) may be explained

Landform modifications within an intramontane urban landscape due to industrial activity, Wałbrzych, SW Poland

The city of Wałbrzych represents a geomorphic landscape, heavily modified by nearly three centuries of industrial activity, related mainly to coal mining. The key landforms due to human impact include spoil tips of various types, extensive levelled terrains, waste ponds, and railway embankments and cuts. Ground subsidence due to mining and water pumping have affected large areas. The map shows the distribution of anthropogenic landforms due to industrial activity, mainly coal mining, over an area of 85 km2. The thematic symbol set for the main map contains 22 classes of objects which show 13 distinctive types of landform modification due to construction, excavation, levelling and complex features. The Main Map is accompanied by inset maps showing generalized geology of the area, extent and magnitude of ground subsidence, as well as relief visualization

Landslide morphology of the south-eastern part of the Wałbrzyskie Mountains, Middle Sudetes

The occurrence of landforms induced by large-scale mass movements has never been reported from the SE part of the Wałbrzyskie Mts., despite detailed geological field mapping carried out twice in the 20th century. This paper provides the first description of landslide-affected slopes in this area, recognized through the combination of LiDAR DEM interpretation and field work. Fifteen landslides have been identified, ranging in size from less than 1 ha to 10.44 ha. Morphological signatures suggest that they represent various types, including minor translational slides, larger rotational complexes and valley-confined flowslides. Closed depressions typify several landslides. In a few instances the valley blocking by landslides can be inferred

Topographic Characteristics of Drainage Divides at the Mountain-Range Scale—A Review of DTM-Based Analytical Tools

We review DTM-based measures that can be applied to study the main drainage divides of mountain ranges. Both measures proposed in the past and new or modified approaches are presented, in order to show an ensemble of tools and jointly discuss their information potential and problematic issues. The first group focuses on the main drainage divide (MDD) as a line running along the range and includes elevation profile, sinuosity, and orientation. The second one includes measures used to compare morphometric properties of two parts of the range, located on the opposite sides of the MDD, such as range asymmetry, morphometric properties of drainage basins, and the position of MDD versus maximum elevation within the range. In the third group, morphometric properties of the terrain immediately adjacent to the MDD are considered. These include properties of areas located far beyond the range symmetry line, topographic asymmetry, longitudinal stream profiles, and relief types derived from automatic landform classifications. The majority of these tools supports identification of sectors of the MDD, anomalous in terms of elevation, symmetry of the range, or the geomorphic context. All these measures were applied to the test area of the Sudetes range in Central Europe

Topographic Characteristics of Drainage Divides at the Mountain-Range Scale—A Review of DTM-Based Analytical Tools

We review DTM-based measures that can be applied to study the main drainage divides of mountain ranges. Both measures proposed in the past and new or modified approaches are presented, in order to show an ensemble of tools and jointly discuss their information potential and problematic issues. The first group focuses on the main drainage divide (MDD) as a line running along the range and includes elevation profile, sinuosity, and orientation. The second one includes measures used to compare morphometric properties of two parts of the range, located on the opposite sides of the MDD, such as range asymmetry, morphometric properties of drainage basins, and the position of MDD versus maximum elevation within the range. In the third group, morphometric properties of the terrain immediately adjacent to the MDD are considered. These include properties of areas located far beyond the range symmetry line, topographic asymmetry, longitudinal stream profiles, and relief types derived from automatic landform classifications. The majority of these tools supports identification of sectors of the MDD, anomalous in terms of elevation, symmetry of the range, or the geomorphic context. All these measures were applied to the test area of the Sudetes range in Central Europe