Terrace Landforms (Dankyū Chikei)

The step-like flat surfaces of this terrain were shaped by the repeated erosion of ancient rivers.

In the Mayama district, a combination of land uplift and river erosion formed this characteristic stair-step topography.
The layers of gravel and sand deposited by the rivers offer excellent drainage, making them ideal for growing Shimonita Negi.

Mayama Course Map

Green Schist

Itabi are thin, flat stone monuments. The green schist found in the Sanbagawa（also spelled Sambagawa) Belt, which stretches from northern Saitama to southern Gunma within the Kanto Mountains, is known as Sanbaseki (Sanba stone).
This stone was widely used in Jomon period stone rods and medieval itabi.

Tōrazu Bridge and Tōrazu Gorge

Lower River Terraces

Along National Route 254, which runs parallel to the Kabura River, you can find a series of lower river terraces. Around 30,000 years ago, during the Late Pleistocene, the Kabura River flowed at this elevation. Repeated flooding events carried mud and sand that gradually filled in the area, creating the broad, flat surfaces of the terraces.

In the southern part of the Mayama area lie mountains such as Mount Kurouchi and Mount Inafukumi, which are part of the Kanto Mountains.
The tributaries of the Kabura River, flowing from the south to the north, cut across these terraces, leaving isolated hills scattered across the Mayama region.

These vantage points, offering clear views of the surrounding area, were ideal locations for mountain castles during the Warring States period.

Among them, Higashi-Mayama Castle was a natural fortress, protected by a steep river terrace cliff formed by the Kabura River to the north and another cliff carved by the Yokose River to the east.

Around 150,000 years ago, when the upper terraces were formed, the Kabura River flowed straight northeast from around the Ishibuchi area through Yokose to Shimokamata.

By about 30,000 years ago, when the lower terraces began to form, the river had shifted course, flowing through Anrakuji, Wakamiya, and Ōtsuka.
Around 10,000 years ago, it moved even farther north to its present-day location, where it began carving out a new valley.
The Tōrazu Valley and the upstream Hanekoshi Gorge were formed during this time.

East Castle

This narrow, elongated castle site protrudes about 300 meters northeast from Beisanji Temple, in a beak-like shape. The current access route from the roadside station (Michi-no-Eki) area is believed to be the main gate approach. The main enclosure (honmaru) is thought to have been located where Beisanji Temple now stands.
Situated on a terrace with excellent visibility, it formed the core of the fortification. Along with Mayama West Castle, located approximately 400 meters away, it is considered to constitute a pair-castle layout, functioning as a single strategic complex.

Beisan Iō-in Beisanji Temple is one of the three temples named “Beisan” along with Echigo Yoneyama (in present-day Niigata Prefecture).

It was founded in 1337 (Engen 2), and the principal image is Yakushi Nyorai (the Medicine Buddha), said to be crafted by the monk Jikaku Daishi (Ennin). The temple is believed to grant blessings related to health and medicine.
It belongs to the Tendai sect, and its treasured possession is the complete collection of the Daihannyakyō Sutra (Great Perfection of Wisdom Sutra).

Pumice from Mount Asama

Gravel Layer of the Upper Terrace

These gravels were deposited by the Kabura River about 150,000 years ago when this area was once its riverbed.

Near the Kabura River, you can see strata where layers of sand and mud alternate.

At outcrops facing the river, the Tomioka Group of the Neogene Period is clearly visible.

Fossils such as shells and shark teeth have been found in these strata, which were deposited in a marine environment about 16 million years ago.

Jōyatō (Night Lanterns)

The Jōyatō stone lanterns are made from different kinds of stone depending on the period in which they were constructed, with sandstone and andesite being the most common.

On some lanterns, the hibukuro (firebox section, third tier from the top) and the shaft (fifth tier) are unusually thin. These parts have sometimes been damaged by earthquakes and later repaired using different stone materials.

Today, Mayama Shrine preserves many Jōyatō lanterns from the Edo period, which have withstood major disasters and remain in their original form since the time they were built.

(Photo: Jōyatō lanterns at Mayama Shrine, left; part names, right)

Located in Wakamiya, Eimeiji Temple is a historic temple said to have been founded in 968 (the first year of the Anwa era) by the Buddhist priest Jikei Daishi. Around the 1470s (Bunmei era), it is believed to have been relocated from the site of Maita Fudō Waterfall to its current location. Today, old stone monuments are arranged throughout the temple grounds.

Beneath the terrace cliffs lies a layer of river gravel deposits. These consist of small, rounded stones shaped by the river’s flow. Because such ground naturally filters and purifies water, many wells have been dug in the area, providing clear, fresh water.

On the right bank of the Kabura River upstream of Tadakawa Bridge, rocks from the Neogene Period can be seen prominently in the terrace cliffs. From a rock shelter (notch) halfway up the cliff, human remains from the late Yayoi period, along with pottery and stone tools, have been discovered.

Note: Access to the river requires crossing private property, so please view the site from the bridge.

Constructed in 1931 (Shōwa 6), this bridge originally served as part of National Route 254. Following the construction of the expressway interchange, it was redesignated as Prefectural Route 48. Due to the local topography, it was built as Gunma Prefecture’s first two-hinged steel truss arch bridge, notable for its beautiful structural framework.

It has been recognized as a “Civil Engineering Heritage Site” by the Japan Society of Civil Engineers.

The main bridges crossing the Kabura River in the Mayama area are Tōrazubashi, Tadakawa Bridge, and Hisaribashi.

Because the river here is wide and the valley is deep, bridges could only be constructed after civil engineering techniques advanced in the Meiji period. Before then, travelers from Tomioka to Shimonita took the Shimonita Road, a route crossing the mountain passes.

When the Kōzuke Railway opened its entire line between Takasaki and Shimonita in 1897 (Meiji 30), even the railway found it difficult to span the Kabura River, so the line was built along the present-day route at the base of the mountains.

Large keyhole-shaped mounds (zenpō-kōen-fun) are mostly found in the area around Jōshū-Ichinomiya Station. West of there, almost all kofun are small, round burial mounds (empun).

On the left bank of the Kabura River lies the Nanajai Kofun Group, while the Mayama Kofun Group can be seen on the right bank. In Shimonita Town, this is the only burial mound preserved in a state close to its original form. The name “Ōtsuka” is thought to derive from it.

Note: This site is on private property; please view it from along the roadside.

According to a 1938 (Shōwa 13) survey of burial mounds in Gunma Prefecture, around 20 mounds once existed in the Mayama area. Later surveys discovered additional mounds in the Shimokamata and Somaze districts. Today, mounds remain in both Ōtsuka and Somaze.

Located at the site of the present Shimonita IC, the Shimokamata Archaeological Site was excavated during expressway construction. Remains and artifacts from periods ranging from the Paleolithic to the Middle Ages were uncovered.

Notably, many pit dwellings from the Middle Jōmon period were identified, revealing that the site had served as a production area for ground stone axes, made using locally sourced stone.

The brown example is a jewel-shaped earring (ketsujō-mimikazari) made from domestically sourced talc. The white, half-broken piece is made of nephrite (soft jade) originating from the Asian continent—a material not found in Japan. A hole drilled at the edge suggests that, after breaking, it was repaired and treasured for continued use.

Dating to the early Jōmon period, around 7,000 years ago, this rare item is considered the earliest form of earrings in Japan, and likely an imported good.

Originally located along the old road from Mayama to Nogami, the Kamata Itabi group was relocated to a hill south of Shimonita IC when the expressway was built. Most are Kōshin-tō (Kōshin stone monuments) made from green schist and similar stone types. Some stand over four meters tall.

From June to July each year, the Hydrangea Festival draws many visitors from within and outside the prefecture. Members of the cultivation society run stalls and rest areas, creating a lively atmosphere. The Geopark Corner features poster exhibits and guided explanations by Geopark Association members.

Along the Nōmen Road on the upper terrace surface of the Mayama Hills, a series of archaeological sites are distributed almost continuously: the Beisan Site, Fujizuka Site, Kannonjibara Site, Nagaone Site, and Shimokamata Site.

In the Jōmon period, people are thought to have lived on elevated hillsides away from the rivers.

During the construction of the Joshinetsu Expressway, excavation work was carried out where the site would be cut through.
Remains ranging from Jōmon-period dwellings to a Sengoku-period castle and temple site were discovered. The Jōbara area, located on the highest river terrace surface, offers a magnificent panoramic view.

This bridge, which spans the main line of the Joshinetsu Expressway, is named after the small locality (ko-aza) of Gongendaira.

When entering Shimonita Town via the expressway, visitors are greeted by views of Mount Myōgi and, in the distance, the distinctive Mount Arafune — a landscape that evokes the feeling of returning home.

At the boundary between the Mayama and Shimonita districts, along National Route 254, the Kabura River flows flanked by continuous 20-meter-high cliffs on both banks. This scenic spot, known as Hanekoshi Gorge, was a bustling destination in the Taishō era, with food stalls set up on the rock surface and a riverside swimming area. A temporary stop for the Jōshin Dentetsu railway once operated here.

Hanekoshi Gorge consists of the Kanohara Conglomerate, a hard rock formation about 70 million years old, containing red-colored clasts that give the entire rock mass a reddish hue. Over time, the river carved this resistant rock into a striking gorge.

Kanohara Conglomerate forming Hanekoshi Gorge

Upstream, on a small terrace about 10 meters above the current riverbed, there is a cylindrical pothole (ōketsu) about 2 meters in diameter and 3 meters deep. It was formed when pebbles, driven by river currents, rotated in place and drilled into the bedrock.

Locally, the deep pool beneath this terrace is called Tarō-buchi, and a folk legend claims that the pothole connects to the Dragon Palace (Ryūgū-jō) from the Urashima story.

According to tradition, in 968 (Anwa 1), the Buddhist priest Jikei Daishi discovered a waterfall here, built a small hermitage, and enshrined Fudō Myōō (Acala).