2017 年 51 巻 p. 68-73
We conducted ground penetrating radar survey on the Chashi Sites of Shibecharigawa basin of Shinhidaka in Hokkaido, with the purpose of investigating the internal structure of the Chashi. The surveyed sites were Shibechari-Chashi and Hoinashiri-Chashi. Shibechari-Chashi was thought to be the fort of Shakushain, leader of Hidaka Ainu. There was the anomaly likely to be a ditch around Chashi. In the case that it was a buried ditch, Shibechari-Chashi would come to have the largest area in Hokkaido. In Hoinashiri-Chashi, the reflection related to the chashi was gained at the main/center part of the site. Also, the anomaly detected on the west side was thought to be the reaction of the buried ditch. These results showed the Chashi was surrounded with the ditch and strengthened its protection.