The copper of the Naganobori Copper Mine was formed by reactions between the limestone of Akiyoshidai and magma about 100 million years ago, and was mined intermittently from ancient times to the modern era. An archaeological dig in the 1980s revealed that copper ore mined here was used to make the Daibutsu (Great Buddha) of Tōdai-ji Temple in Nara, while the Naganobori Copper Mine was the oldest nationally-run copper mine in Japan. Excavations have found many ancient objects and the remains of structures, some of which are exhibited at the Naganobori Copper Mine Cultural Exchange Centre (Daibutsu Museum).
The remains of kilns for creating a type of pottery called sueki, active from the Nara period to the beginning of the Heian period. Five kilns have so far been discovered in an east-west line on the southern slope of the hill. Of these, two are built on top of one another, providing extremely important clues to the chronology of sueki production.
On sandstone boulders near the top of the mountain can be seen several line carvings of the Buddha. The age of, and reason for, the carvings is unknown.
The Aokage silver mine was mined for a period of 66 years from 1573 for silver which was formed by the reaction of the limestone of Akiyoshidai with magma approximately 100 million years ago. Among the ruins, a gallery (a tunnel mined for silver) still remains, and its wall bears marks of chiselling. A village at the foot of the silver mine still maintains place names, household names and old wells dating back to the era when it prospered on account of the silver mine.
The Arakawa mine gallery was mined for anthracite, a form of coal which emits little smoke when burned. Completed in 1905, this is the oldest existing gallery/shaft in the Ōmine Coalfield. At this valuable heritage site dating back to the Meiji Era, you can still see old brick walls inside the shaft. ※Only guided visitors can enter the shaft.
The Mine inclined-shaft mine was one of the most important coalmine shafts in the Ōmine Coalfield, which produced anthracite. A large amount of coal mined underground was carried through this shaft to the ground. In the past, there was a railway station near here to transport coal away.
Lime was produced here from the middle of the Meiji period (1880s) to the middle of the Shōwa period (1950s). Limestone used for the lime-producing process was brought from the mountains to the south-east, and anthracite from the north and west. The lime produced here was used as fertiliser for fields, as the basis of cement and for a type of Japanese plaster called shikkui.
Chōjaga-mori is a virgin forest made up of approximately 66 plant species. Of these, a species named tabunoki (Machilus thunbergii), belonging to the laurel family, dominates the forest, with tabunoki trees of around 16m in height covering most of the area. Thick with tall trees forming the canopy and understorey, the forest has little underbrush. It is said that the forest was given its name, which literally means ‘rich man’s forest’, on account of a tale that a wealthy man had lived here in isolation from society long ago.
Located in Western Akiyoshidai Karst Plateau, the Yowara hamlet in Shūhō-chō is built in an uvala, a valley-like depression formed when multiple dolines combine. Isolated from other hamlets, houses in the Yowara hamlet are concentrated in the cone-shaped valley. Because of the hamlet’s location in the karst, there are no rivers on the ground, and rainwater flows underground through multiple vertical holes called “ponors” in the uvala. Therefore, farmers in this hamlet mainly cultivate vegetables, and grow little paddy rice.
A doline farming area denotes farmland using the bottom of a doline, a cone-shaped sinkhole in limestone. It is known that the bottoms of dolines in the Akiyoshidai karst plateau were cultivated as fields as early as the Edo Period. The bottoms of dolines are relatively flat and well drained, and so suitable for cultivation; but the farmland, which is too small for vehicles and farm machines to enter, came to be mostly abandoned due to farm mechanisation and the increasing size of farm machines. Today, some local farmers continue to cultivate burdock, potato, Chinese cabbage and other vegetables in some of the dolines.
The Ōda/Edō military stronghold ruins are the site where forces led by Takasugi Shinsaku, Yamagata Aritomo, Itō Hirobumi and others placed their stronghold at a battle within the Chōshū Domain during the final years of Edo Period, where they held strategy meetings and prayed for victory. The ruins are located to the north of the road in the Ōda area, Mitō-chō, where a shrine named Kinreisha stands today.
The stalactites of Suijin Park are worshipped as a manifestation of Munemamori, guardian god of pregnant women. As water containing dissolved limestone runs down the rock, the stalactites grow like icicles hanging from the rock. Because the stalactites here resemble a pair of breasts, it was believed that drinking this water would cause women to produce more milk.
The terraces here are located where a mountain valley opens up. In the past, floods of mud, sand and water have flowed through here. This type of flow is known as a debris flow or mudslide; the land formation here is known as a debris fan. The name of the area – Ōishi, literally meaning ‘big rocks’ – likely originates from boulders carried here by mud flows. The fields constructed on the steep sides of this hill are used as rice paddies.
A limestone cave of approximately 1km in length, located near the source of the tap water in the village of Ōda in Mitō-chō. Located in the upstream part of Akiyoshidō, the cave here connects to a branch cave of Akiyoshidō. The cave also connects to a shaft drilled as a waste dump for the last mine to close at Naganobori; this man-made shaft can be seen today extending from the natural cave. As well as slag from mining activity near the cave entrance, inside the cave malachite and marble can be seen. The natural entrance to the cave is a vertical hole around 50m from top to bottom.