A significant development of sandbars can be seen at the entrance of Lake Tofutsu, one of the lagoons located along the Okhotsk Sea in Hokkaido, Japan. The authors have evaluated the sequential sedimentation history of the sand bars by means of MASW (Multi-channel Analysis of Surface Waves). The purpose of this study is to verify this sedimentation history through soil sampling and laboratory testing at some typical points along the arrays of MASW. Sampling method was modified to be suitable for low-cost soil investigation at tidal flats. The samples collected were examined in the laboratory to obtain the depth profiles of grain-size distribution and carbon 14 dating. The results obtained in this study are consistent with the sequential sedimentation history evaluated by MASW.
