Production Years of Iron of Old Japanese Nails of Amanosan-Kongo-ji and Kasugataisha Shrine Calibrated from ¹⁴C Age

Abstract

The production age of iron of old Japanese nails used at the eaves of the Kondo (main hole) of the Amanosan-Kongo-ji temple and the corridor of the Kasugataisha shrine was measured by the ¹⁴C age method. The ¹⁴C concentration of charcoal absorbed by iron during ironmaking is the value at the time of logging, and it was taken into consideration that the trees were logged between 20 and 25 years old. By referring to the history and repair records of each temple and shrine, it was found that iron for the nails at the Kongo-ji temple and the Kasugataisha shrine was produced between 1150–1155 and 1555–1560, respectively. These values were compared with the production year of iron of the old Japanese nails at the Daibutsuden in the Todai-ji temple, the Kuri in the Kyoto Manshuin temple and the Zaodo in the Yoshino-Kinpusen-ji temple in the previous report.¹⁾ It was found that the iron production years of the nails at the Kasugataisha shrine and the Kinpusen-ji temple were the same, and there was a difference of 80 years in the production years between the two nails at the Kinpusen-ji temple.

¹⁴C date (BP) and calendar year (AD) of the old Japanese nails with the probability of ±2σ at (a) the Eaves of Kondo in the Amanosan-Kongo-ji temple (No. 1) and (b) the corridor in the Kasugataisha shrine (No. 2). (Online version in color.)