9 research outputs found
Gilbert-style Pleistocene fan delta reveals tectonic development of North Island axial ranges, New Zealand
Whanganui Basin, an archive of prehistoric earthquakes? Waitapu Shell Conglomerate (c. 0.9â Ma), North Island, New Zealand
Landscape evolution and hydrogeochemical characteristics of the Pourewa Stream catchment, lower North Island, New Zealand
A review of lahars; past deposits, historic events and present-day simulations from Mt. Ruapehu and Mt. Taranaki, New Zealand
Age and isotopic characterisation of metasedimentary rocks from the Torlesse Supergroup and Waipapa Group in the central North Island, New Zealand
What and where are periglacial landscapes?
Uncertainties about landscape evolution under cold, nonglacial conditions raise a question fundamental to periglacial geomorphology: what and where are periglacial landscapes? To answer this, with an emphasis on lowland periglacial areas, the present study distinguishes between characteristic and polygenetic periglacial landscapes, and considers how complete is the footprint of periglaciation? Using a conceptual framework of landscape sensitivity and change, the study applies four geological criteria (periglacial persistence, extraglacial regions, iceârich substrates, and aggradation of sediment and permafrost) through the last 3.5 million years of the late Cenozoic to identify permafrost regions in the Northern Hemisphere. In limited areas of unglaciated permafrost regions are characteristic periglacial landscapes whose morphology has been adjusted essentially to present (i.e., Holocene interglacial) process conditions, namely thermokarst landscapes, and mixed periglacialâalluvial and periglacialâdeltaic landscapes. More widespread in past and present permafrost regions are polygenetic periglacial landscapes, which inherit ancient landsurfaces on which periglacial landforms are superimposed to varying degrees, presently or previously. Such landscapes comprise relict accumulation plains and aprons, frostâsusceptible and nonfrostâsusceptible terrains, cryopediments, and glacialâperiglacial landscapes. Periglaciation can produce topographic fingerprints at mesospatial scales (103â105 m): (1) relict accumulation plains and aprons form where longâterm sedimentation buried landsurfaces; and (2) plateaux with convexoâconcave hillslopes and inset with valleys, formed by bedrock brecciation, mass wasting, and stream incision in frostâsusceptible terrain