Ikawa and Higashimiyoshi Area

The Sanuki Mountain Range is mainly made up of layers of sandstone and mudstone. These layers form a large, upside-down arch shape, known as a syncline. The axis of this arch can be seen along the Masukawatani River. These sand and mud layers were originally deposited on the ocean floor about 80 million years ago. As the layers were gradually uplifted, they tilted eastward. This process formed the syncline structure we see today—shaped like the letter "U."

This is an outcrop of the fracture zone of the Ikeda Fault, located along the riverbank in Kamo. It was exposed when heavy rainfall in July 2018 caused flooding in the Yoshinogawa River, washing away rocks along the riverbank. Today, you can see the fracture zone of the Izumi Group (black color), which forms the land north of the MTL, and the fracture zone of the Sambagawa crystalline schist (greenish-gray), which makes up the land to the south.

Yatsuishi Castle once stood along the route connecting the Inouchi Area, Shitsukawa Area, and Iya Area. Built on the tip of a mountain ridge at an elevation of around 800 meters, the castle was surrounded by rugged terrain. The remaining stone walls are made from rounded, fist-sized rounded conglomerate rocks.

Mt. kaina features a gentle summit and a soft, rolling ridgeline. The landscape is shaped by a linear depression, a long, narrow landform created by past landslides. Thanks to its cool temperatures and mild terrain, the area offers ideal conditions for open grazing during the summer months.

In the Minoda area, the steady flow of the Yoshinogawa River has carved into the riverbed, made of crystalline schist, creating a stream pool. This natural formation stretches about 2 km in length and 100 meters in width. Near the Yoshinogawa Highway Oasis rest area, you will find striking features like large rocks made of psammitic schist. If you look closely near the Minoda Ohashi Bridge, you can also spot outcrops of greenschist in the stream pool.

The Ashirohigashibara site features a keyhole-shaped bruial mound and a group of cairns, believed to date back to the 3rd Century AD. During the Yoshinogawa North Riverbank Irrigation Project, which began in 1981, a stone-piled tombs and more than 36 cairns were uncovered across a 180-meter stretch from west to east. These tombs and cairns are made of sandstone breccia sourced from the nearby Sanuki Mountain Range.

The shrine precinct stands on a fluvial terrace, slightly elevated from the surrounding area. Visitors reach the shrine by climbing a set of steps, one of which marks the height of the river during a major flood caused by 'Typhoon June' in September 1954. Metal studs embedded in the step show how high the water rose, offering a powerful reminder of the typhoon’s impact. The difference in elevation between the town road and the shrine grounds is 4.1 meters.

This giant camphor tree (Cinnamomum camphora) stands in the flatlands formed by sediments from the Yoshinogawa River. Its roots stretch around 23 meters in circumference, and its trunk measures about 16 meters around. Estimated to be around 1000 years old, the tree has withstood countless thunderstorms and windstorms over the centuries. With its long, spreading branches, the tree appears to embrace both the sky and the earth. Standing beside it, you can feel its enduring strength and presence.

Tanda Kofun is located along the trail leading up to Mt. Kamoyama, near the tip of a ridgeline at an elevation of about 320 meters. This stone-piled tomb is constructed from various types of conglomerate, composed of crystalline schist. At the rear of the tomb, a pit chamber has been installed, and its entrance remains open. Inside the chamber, several burial items were discovered, including a bronze mirror, iron swords, and iron axes—typical grave goods from the late 3rd to the end of the 4th century.

Iwakage Ruins are located along the Kamodanigawa River, where it is believed that hunters once set up camp in ancient times. A massive rock of crystalline schist broke apart and collapsed along its schistosity planes, where the rock naturally splits due to aligned mineral grains. The resulting hollow space was once used as a campsite for hunting.
The site includes a scattering of small ruins across the area, each marked with a number for preservation and study. Artifacts dating back to around 10,000 BC and 1,000 BC have been discovered at Ruins No. 1, 2, and 5.