Steilhang
A Steilhang (pl: Steilhänge) is a geoscientific term for a mountainside or hillside (or a part thereof), the average slope of which is greater than 1:2 or 30°. The term is German for "steep slope/mountainside/hillside". The word Hang in this compound may be similar in origin to the English word "hangar" used to mean woods on steep hillsides e.g. for the East Hampshire Hangers.
Geology
The formation of slopes of different gradients depends on the one hand on the type of underlying rock of the mountain or hill - and this may result in slopes varying from those on the other side of a mountain, hill or valley – and on the other hand on its local hardness, and circumstances of its deposition (sedimentation, stratigraphy, bedding or jointing), on its resistance to erosion and not least on the water flow and local climatic conditions.
From a geomorphological standpoint, there is a distinction made between steilhänge not simply on the basis of their gradient and rock type, but especially on their aspect (i.e. their orientation), their rotundity or roughness (small shapes, flexion, steps, terraces, drainage etc.), the vegetation on the mountainsides or hillsides and the soil formation.
For example, the soil type known as ranker gets its name from the word Ranker which is commonly used in Western Austria to mean steilhang.
Natural dangers
Steilhänge present various natural dangers if they are not forested or interrupted by gentler slopes:
- Landslides – especially if the soil is saturated after long periods of rain or during snowmelt
- Collapse – if there is a rock face or heavily eroded crags above, or
- Rockfall, a less severe occurrence
- Destruction caused by mudflows during bad weather or avalanches
- episodic or sudden rock creep, that may threaten to impound water.