Japan Geoscience Union Meeting 2016

Presentation information


Symbol H (Human Geosciences) » H-GM Geomorphology

[H-GM14] Geomorphology

Mon. May 23, 2016 5:15 PM - 6:30 PM Poster Hall (International Exhibition Hall HALL6)

Convener:*Hiroshi Shimazu(Department of Geography, Faculty of Geo-Environmental Science, Rissho University), Masayuki Seto(Fukushima Future Center for Regional Revitalization, Fukushima University)

5:15 PM - 6:30 PM

[HGM14-P02] Examination of the paleo-sea level inferred from emerged wave-cut features
along the west coast of the Noto Peninsula, central Japan

*Wataru Kobayashi1, Masaaki Hamada1, Hiroshi Okuyama2, Hirofumi Yamamoto3 (1.Hokuriku Electric Power Company, 2.Former Fukui University, 3.Fukui University)

Keywords:sea cave, wave-cut notch, paleo-sea level

In the west coast of the Noto Peninsula, the crust deformation in Holocene has not been revealed because of lack of the reliable indicator of paleo-sea level. The wave-cut notch is able to be the indicator, but it is difficult to distinguish them from futures formed by salt weathering which are abundant on surface of sea cliffs in this area (Kobayashi et al., 2015). In addition, the distribution of the wave-cut notch is controlled by rock types and cracks, and they formed above sea level because of wave convergence due to surrounding landform. Therefore identification of paleo-sea level is not easy.
Ito et al. (2002) revealed that the height of the retreat point of the notch in sea caves was almost equal to paleo-sea level recognized from erosive futures around the cave in the Echizen coast, central Japan. In the west coast of the Noto Peninsula, notches in sea caves are also formed and most of them are not constrained by geological structures. Moreover, these features are well preserved from weathering. Therefore, the present study aimed to reveal the height of wave-cut notches in sea caves and that on the sea cliffs which coexist with benches and are not controlled by geological structures along the west coast of the Noto Peninsula. The measurement of the height was demonstrated not at the recess but near the entrance of sea caves to avoid influence of convergence of waves.
The investigation revealed that paleo-sea level records estimated from wave-cut notches were around an altitude 2 m. These futures are considered to form at the same time from vicinity of them. Therefore, the crustal tilting from the time these futures formed to the present is not seen in this area.
Ito, D., Kinoshita, Y., Yamamoto, H., 2002, Reexamination of the paleo-shoreline inferred from the sea caves along the Echizen coast, Fukui Prefecture, Japan. Memo., Edu., Univ., Fukui, no.54, p.19-46.
Kobayashi, W., Hamada, M., Yamaguchi, H., Takayama, T., Ishigami, S., Hiramatsu, Y., 2015, Shapes and origins of notches and caves on sea cliffs, the Noto Peninsula, central Japan. Abs, Sub, JpGU, meet, 2015, HGM22-P04.