Oyu Stone Circles
More than 8000 stones are arranged in two large circles at this archaeological site in Kazuno, Akita. The monuments date from around 2000 BCE and are positioned in a way that demonstrates an understanding of the sun’s movements. Constructing them would have required immense effort and careful planning. An on-site museum provides information about the stone circles and exhibits earthenware, ritual objects, and other artifacts uncovered at the site.
Characteristics of the stone circles
Both circles are made up of inner and outer rings of stones grouped together in small arrangements. Within the rings of each circle, there is a set of stones arranged in a radial pattern around a single standing stone. These radial arrangements resemble sundials, and during the summer and winter solstices, they cast shadows in a single line along a northwest-southeast axis. Archaeological surveys have revealed burial pits beneath the stone arrangements, and archaeologists believe each individual arrangement marks a grave.
Manza Stone Circle
At 52 meters in diameter, the Manza Stone Circle is the larger of the circles. Approximately 6500 stones were used in its construction, and more than 100 arrangements have been identified.
Nonakado Stone Circle
The Nonakado Stone Circle is located roughly 100 meters from the Manza circle. Approximately 2000 stones and more than 60 arrangements comprise the Nonakado Stone Circle, which measures 44 meters in diameter.
Archaeological findings
The foundations of four- and six-pillar structures were revealed around the outer rings of the stone circles together with deposits of objects thought to have been used in rituals. Due to the characteristics of the foundations and the large quantities of ritual items found nearby, archaeologists believe the structures had a ceremonial function and were not inhabited. Several structures built around the Manza Stone Circle give visitors an idea of how the circle might have looked 4000 years ago.
Construction of the stone circles
Archaeologists estimate construction of the stone circles took more than 200 years. The heaviest stones weigh more than 200 kilograms. They would have been transported from rivers up to 4 kilometers away using only simple implements.
Green stones
Many of the stones used in the Oyu circles have a greenish hue. They are a particular type of stone originating on Mt. Morosuke, several kilometers east of the circles. The stones would have made their way downstream from the Akuya River, which runs through the foothills of Mt. Morosuke, into the Oyu River, the river closest to the archaeological site. It is not known why these particular stones were favored in the construction of the circles, but they likely had a special significance.
Oyu Stone Circles Museum
Hundreds of clay vessels (doki), clay figurines (dogu), clay tablets (doban), and stone objects unearthed through excavations are displayed at the Oyu Stone Circles Museum. The pottery works include large, urn-like vessels used to inter the remains of the deceased and elaborately decorated bowls and vases. The stone objects are mostly small and fashioned into shapes such as swords, bowls, and flat, triangular plates. Everything excavated is ornamental and believed to have served a ceremonial purpose.
Related archaeological sites
Other large prehistoric monuments in northern Japan include the stone circles of Isedotai [link] (Akita), Washinoki [link] (Hokkaido), Komakino [link] (Aomori), and Omori Katsuyama [link] (Aomori).
