Caves in non-limestone rocks of Norway

The gneisses and schist bedrock in Bjugn, Åfjord and Ål counties of Norway are remarkably rich in caves and shelters. The caves are mainly developed along tectonic structures, primarily prominent fissure zones and nappes. Five modes of origin seem reasonable:

1. Tectonic movements and gravity sliding, producing displacement of hillsides.

2. Frost shattering.

3. Wave abrasion during stages of high sea-levels.

4. Preferential weathering in brecciated zones.

5. ‘Karstic’ dissolution of small, isolated marble lenses within the gneisses.

In many cases, two or more of the processes appear to have worked together. Abundant speleothem growth suggests that calcareous zones exist in the rocks.

The caves reach a horizontal extent of up to 200 m and vertical depths of 55 m. These much neglected cave types arc valuable shelters and habitats for animals, as well as paleontologically important pit-fall traps. Some of the caves and shelters are also potential archeological localities.