[O02-P50] The origin of the pumice bed distribution around Seki in Gifu Prefecture, Central Japan.
Keywords:Late Pleistocene, Ontake volcano, Mud flow deposits
In the outcrop of Tubo River flowing through Shimokurachi in Seki City Gifu prefecture, I found a pumice bed.
Its pumice stone from Mt.Ontake once carried by the Old Kiso River of a different flow passage now.
I made a hypothesis and advanced the study.
As a result, the pumice bed concluded that the pumice called Pm-I~III which Mt.Ontake erupted about 600 to 900 thousand years ago was carried by the Old Kiso River and a part of it was pooled again in Seki.
Also , by about 50 thousand years ago , I propose a theory that passes through the Kiso River a little more north than the general theory.
Its pumice stone from Mt.Ontake once carried by the Old Kiso River of a different flow passage now.
I made a hypothesis and advanced the study.
As a result, the pumice bed concluded that the pumice called Pm-I~III which Mt.Ontake erupted about 600 to 900 thousand years ago was carried by the Old Kiso River and a part of it was pooled again in Seki.
Also , by about 50 thousand years ago , I propose a theory that passes through the Kiso River a little more north than the general theory.