周氷河地形プロセス研究最前線

Abstract

Periglacial process studies, which began in the mid-20th century, have greatly advanced in recent years following several breakthroughs. This paper reviews the latest breakthroughs supported by new technologies, themes, and international projects. New technologies have enabled small, high-resolution data loggers to monitor rock and soil movements, and thermal and hydrological properties in polar and alpine areas; enabled geophysical instruments to visualize two- and three- dimensional subsurface structures below periglacial features; and, enabled numerical simulations to predict future landform evolution. In particular, dramatic progress has been achieved in understanding bedrock shattering and falls, soil movements induced by freeze-thaw oscillations, controls on rock glacier creep, critical conditions for ice-wedge cracking, and biogeophysical impacts on non-sorted circles. Two key words, global warming and Mars, are appearing often in periglacial research. High mountains and polar lowlands face the fate of potential natural hazards associated with rock slides, debris flows and thermokarst subsidence, possibly originating from permafrost thawing. High-resolution orbital images and on-site explorations on Mars provide detailed information on small-scale, potential periglacial features, which are the morphologically equivalent of terrestrial counterparts. International collaboration is expected to further promote modeling various periglacial features on a global scale, improve the resolutions of periglacial climate indicators, and increase understanding of past and present Martian environments.