Pillar holes found in moat around ancient burial mound in Osaka
SAKAI, Osaka -- Nearly 30 pillar holes have been discovered in a moat surrounding an ancient burial mound here, leading experts to believe they may have been for a bridge used for a funeral of the person buried in the mound.
The Sakai Municipal Government announced on Feb. 21 that 29 pillar holes and two pieces of oak lumber that were apparently used as pillars were found in the moat on the eastern side of the round-shaped part of the tomb at the Nisanzai burial mound in Sakai's Kita Ward, which dates back to the late 5th century. Experts have pointed to the possibility that the holes were for pillars supporting a bridge used for carrying a coffin of the deceased and other materials into the mound.
It is the first time in Japan that pillar holes for a structure believed to be a bridge have been discovered in a moat surrounding an ancient burial mound, city officials said. The find is a precious one that could provide clues to the construction process of ancient burial mounds and burial methods. Previously, a bridge made of earth left in place during the digging of an ancient burial mound moat was found in that moat, the officials said.
According to the city, there are seven rows of pillar holes stretching from north to south, one of which extends to the central part of the moat. Pillar holes were also found near the embankment of the moat. It is likely that those holes were for a sequence of pillars supporting a bridge over the moat.
"The discovery of these remains is something unexpected. We should assume that similar remains exist at other ancient burial mounds, and this survey is of great significance in that respect. The usage of the pillar holes couldn't have been anything other than for a bridge, and it's possible the bridge was a splendid one using all the seven rows of pillar holes that have been discovered," said Taichiro Shiraishi, director of the Chikatsu Asuka Museum in Osaka Prefecture.
According to the city government, the pillar holes each measure one meter square and up to around one meter deep. The width of the part of the moat where the pillar holes were discovered stretches some 40 meters. Near the round-shaped part of the mound, the pillar holes were concentrated around the part of the mound believed to have been above the surface of the water at the time of construction. Excavators found seven rows of pillar holes lying north and south at intervals of 1.6 to 2.1 meters, as well as three rows of pillar holes lying east and west at intervals of 1.6 to 1.8 meters.
Among the seven rows of pillar holes lying north and south, the fourth row from the north had five more pillar holes lying toward the embankment on the eastern side. Those pillar holes were found at a depth of 2.4 meters from the bottom of the moat. Two other pillar holes were also found at around four meters away from the embankment, along with two other pillar holes on the south side. The fourth row of pillar holes lies almost on an extension of the main axis of the mound connecting the hearts of the front rectangle-shaped part and the rear round-shaped part of the mound. The holes were apparently dug around the time the burial mound was completed, based on surrounding geological formations, according to city officials.
Ryuji Kuroda, professor at Kobe University graduate school, pointed to the possibility that there had been a two-tiered stage at the mound-side end of the bridge where rituals were held, on the grounds that the intervals of the pillar holes are different on their north and south sides. He produced a replica of the bridge based on the findings of the pillar holes.
"The pillars are believed to have been thin and lightly built but were systematically arranged, which indicates that builders had overwhelmingly high technical capabilities," Kuroda said.
The Nisanzai burial mound lies at the eastern edge of the Mozu Tumulus Group, which includes the Daisen burial mound (the tomb of Emperor Nintoku) and is administered by the Imperial Household Agency. Legend says Emperor Hanzei, the son of Emperor Nintoku, was buried in the Nisanzai mound.
February 22, 2013(Mainichi Japan)