The Sea of Rocks in Kui and Yano
The Sea of Rocks in Kui is on Mt. Une (698.8 meters), which is at the eastern
tip of Kui-cho (Mihara City). The "sea" is seen around an altitude of 500 meters.
The sea of rocks is said to be a periglacial feature. This is a geological,
topographical phenomenon, in which water in the cracks of rocks freezes due to
low temperatures, causing the rocks to crack apart and roll down.
Seas of rocks in Kui are found along three valleys. The one on the west side
(650X65 meters) is called Zenigame-gouro. The one in the middle (350X35
meters), is called Naka-gouro (naka: middle). 0-gouro is the name given to the
one on the east side (350X100 meters). These are seen in a layer about 2 to 3
meters thick. The diameters of some large rocks are as much as 15 meters.
The sea of rocks in Yano is in the southern part of Joge-cho (Fuchu City). The
rocks there are larger in diameter than those in Kui. Huge rocks with an average
diameter of about 5 meters form a layer 7 meters thick and 70 meters in length,
lying on top of one another.
In both Kui and Yano, rocks that form the sea are mostly granite. Since these
periglacial features are quite precious in terms of scientific value, they were
designated as natural monuments of Japan in 1964.
It looks more like a big river made of rocks than a sea (Photograph taken circa 1994)
Besides this sea of rocks, Kui-cho (Mihara City) was famous for its cattle and horse sale fair since olden days. The town retains little trace of its past prosperity, only its market and posts to which cattle and horses were tied up, for which it is designated as a historic site of the prefecture.
Mt. Une Astronomical Observatory is another point of interest. Joge-cho (Fuchu City), in addition to its sea of rocks, has the Yano Onsen or Yano Hot Spring, with its garden of irises. The sea of rocks in Yano has been a habitat of phinolophus ferrumequinum, so it has long been called Komori-iwa, or rocks of phinolophus ferrumequinum.