Jomon Water Transportation of Obsidian and Volcanic Activity: Excavation and Analyses of the Yokoo Coastal Wetland Site, Japan

Abstract

This paper reports on the investigation of Yokoo Site, a Jomon site, by the Oita Municipal Board of Education. Yokoo is located in Oita city on Kyushu Island in the western part of the Japanese archipelago. Japanese archaeologists have recognized Yokoo as a Jomon site with a shell mound since it was discovered at the beginning of the twentieth century. Yokoo is one of Japan’s most important sites for the history of archaeology. Until our investigation, the biggest part of the Yokoo site, which is the area without the shell mound, had been obscured and impossible to excavate.The purpose of the research described here was to investigate the structure and characteristics of Yokoo Site using various geo- and environmental archaeological methods. As a result, it was found that Yokoo Settlement was a relay station for the transportation of Himeshiman obsidian along a sea route during the Initial to Late Jomon period. Himeshima, an obsidian resource, was a mountain during the Jomon period, but due to marine transgression is now an island off the coast of the Kunisaki Peninsula. Himeshiman obsidian was transported across the Seto Islands Sea and the Inland Sea of Japan, which formed during the same period. Himeshiman obsidian is an important archaeological material and was transported across the Seto Islands Sea via a marine route in 7900–7300 cal BP. However, geoarchaeological research shows that on one occasion that transportation was interrupted by a natural disaster, the eruption of Kikai Caldera in 7300 cal BP. The Yokoo site shows not only human adaptation to the ongoing marine transgression but also remarkable evidence of an instantaneous human event during this, the greatest volcanic disaster since the formation of the Japanese Archipelago.