The morphology of peat bog surfaces on Hermansenøya, NW Svalbard

This article analyses the surface morphology of the arctic peat bogs occurring on Hermansenøya, a small island in the Forlandsundet, NW Svalbard. Six small, shallow peat bogs on the island show different microrelief features formed by ice-segregation as well as thermokarst and thermo-erosion processes. On the peat bogs the following forms have been identified: aggradational, associated with the growth of different types of ground ice (frost peat mounds, peat plateaus, polygonal peat plateaus, networks of ice-wedge polygons); and degradational, associated with thermokarst (symmetrically developed residual peat mounds and the furrows in between) and thermo-erosion (channels of niveo-fluvial streams). Some importance can also be attributed to aeolian processes, i.e. snow drifting from the tops of convex relief features for aggradational forms. Lack of insulating snow cover significantly increases frost penetration depth, promoting cryosuction and/or ice growth at the base of a frozen core. The oldest preserved forms and structures, frost peat mounds with an ice-peat core and ice-wedge polygons, developed during climatic cooling at the turn of the Subboreal and Subatlantic (c. 3.0-2.5 ka BP). Thermokarst mounds are younger, associated with warmer periods after the Little Ice Age (the warmer 1920s). Channels of niveo-fluvial streams are being shaped today.