Landscape change on Shirasu plateau: Diversity from flovial and aedian process

Abstract

Shirasu ignimbrite plateau was formed rapidly immediately after the Aira-Ito eruption (29 cal ka), owing to enhanced ephemeral erosion and denudation on the pyroclastic field. It has been generally considered that aeolian process was almost only geomorphic factor on Shirasu plateau after the drastic dissection of initial topography. However, recent observations of upland deposits at successive trench show the non-uniformity of landform evolution on plateau surface. In this presentation, new findings are introduced with respect to buried gully, tephric loess and deposition of Kikai-Koya pyroclastic flow, and landscape change on Shirasu plateau is summarized, based on some cases in northern and middle part of Osumi Peninsula. This diversity, derived from fluvial and aeolian process, should be paid attention in terms of ecological and archaeological implications.