12:15 PM - 12:30 PM
[HQR23-09] Longitudinal river profiles crossing marine terraces at northern part of western Osado coast, Sado Island, central Japan
Keywords:river knickpoint, uplift, rocky coast, coastal erosion, digital elevation model, Pleistocene
Retreat of sea cliffs and river knickpoints associated with coastal erosion would have finished when the Holocene marine terraces emerged. After the emergent, the river knickpoints retreated by fluvial incision. Distances between sea cliffs and river knickpoints could be distance of knickpoint retreat. The distances are detected as 100-150 m based on 1:25,000 topographic maps and DEM analysis. Assuming that the emergent occured during 7-8 ka, the rates of knickpoint retreat range 12-21 m/ky. These rates could be high enough to dissolve old river knickpoints, formed on or before the Last Interglacial period (MIS 5e).