6:15 PM - 7:30 PM
[MIS23-P01] Japanese continental drift theory mentioned over 1200 years ago, before the Wegener's theory
Keywords:Izumo Province fudoki, Kunibiki myths, Shimane peninsula, early Miocene, Continental drift theory
Izumo-no-kuni-fudoki (The Izumo Province fudoki) was compiled in 733, which was 1282 years ago. A very stimulated story, the Shimane Peninsula was formed as added the land pulled part from the peninsula, somewhere of Shiragi, old name of Korean country (A.D. 6~10 century). This story is very popular in Japan, known as "the Kunibiki myths." The physicist and essayist, Torahiko Terada, took up this story just like the Wegener's "Continental Drift Theory" in his essay of "Geophysicist and mythology." Up to the present, no one discussed the place where is the peninsula of Shiragi. However, the place is clearly located in Korea.
One more stimulated concern on this story is the paleomagnetic reconstruction of early Miocene Honshu Island. Clock-wise rotation of southwest Honshu Island has been well studied, and the geographic location of southwest Honshu Island in the early Miocene is clarified as being very near Korea.
We investigated the geology of the Pohang basin and its neighboring area. The early Miocene series of the Guryompo Peninsula are mainly composed of the Beomgogni Group and Janggi Group, both of which are characterized by volcaniclastic rocks such as dacite and andesite. Lithology of shale in the Janggi Group is similar to that of the Koura Formation distributed in the Shimane Peninsula, which yields brackish fossil Corbicula. The geologic ages of the Beomgogni Group and Janggi Group are ranged in 22~17Ma, earlier ages of which are also similar to those of the Koura Formation.
Surprisingly enough, the story of the "Kunibiki myths" suggests the people 1300-years ago figured out geographic nature of the earth that is unchanged with the present view of the earth. The "Kunibiki myths" never mentioned the geological reason, why is the Guryompo peninsula similar to the Shimane peninsula. However, we suppose the myths have been born through the people interchanged between Shiragi and Izumo countries. We suggest thus high potential of people's observing ability to the geology and topography of the earth indicated in the "Izumo Province fudoki."