Paraglacial Geomorphology

Paraglacial geomorphology is the study of how nonglacial earth-surface processes modify glaciated landscapes. Glacier retreat exposes glacigenic and glacially conditioned sediment sources (rockwalls, drift-mantled slopes, valley-floor glacigenic deposits, and coastal glacigenic deposits) in an unstable or metastable state. During sediment reworking, source-to-sink transport is interrupted by storage in a range of paraglacial landforms such as talus, debris cones, alluvial fans, valley fills, deltas, and coastal barrier deposits. Because glacigenic sediment sources are nonrenewable, paraglacial sediment flux can be approximated by an exhaustion model, and sediment stores experience a transition from net accumulation to net degradation. Six paraglacial land systems are identified (rock-slope adjustment, drift-mantled slopes, glacier forelands, and alluvial, lacustrine, and coastal settings). Paraglacial effects dominate the postglacial geomorphic evolution of most glaciated environments.