ABSTRACT
The paucity of surface vegetation due to glacial erosion, soil erosion, and the harsh climate renders alpine karst features more easily seen and appreciated than in other environments. Solutional features like karren are often well developed in suitably massive, pure carbonates, and the resulting lapiaz or limestone pavements can cover many square kilometres (see figure). Such surfaces are composed of numerous, structurally controlled closed depressions, indicating highly fragmented recharge. Larger closed depressions may occupy tectonic structures, or may occupy cirque floors or valleys previously overdeepened by ice. However, many alpine closed depressions act as agents of their own burial. They are filled with clastic deposits generated by weathering, mass movement, glaciation, and runoff, and the sink points are unable to carry the coarse materials involved. In time, if the terrain stabilizes, suffosion dolines may develop in the fill, eventually leading to reopening of the ponor. For example, Medicine Lake, Jasper National Park, Canada occupies a karst depression blocked by a rock slide, glacial deposits, and river sediments. It has failed to develop a significant ponor due to continuous infilling of nascent openings.
