Nivation and cryoplanation: the case for scrutiny and integration

Nivation and cryoplanation are deeply entrenched and widely invoked morphogenetic concepts within periglacial geomorphology. However, given their complexity and purported significance in landform development, neither has received the scientific scrutiny merited. Nivation is generally associated with the weathering and mass movement processes stemming from late-lying seasonal snow and the ensuing landforms. As a process suite it invokes mechanisms such as freeze-thaw weathering and solifluction. Cryoplanation also invokes a process suite, but one that also embraces nivation. Research in the last two or three decades has begun to provide a much sharper definition of nivation, but the available information is still inadequate for a central mechanism in periglacial landscapes. Cryoplanation is used to explain some benches, terraces and pediments that appear to be widespread in some periglacial environments: however, substantive field research on the mechanisms involved is all but absent. A case is presented for viewing nivation and cryoplanation as a single process spectrum much in need of state-of-the-art research.