Nagatoro Iwadatami

This is a beautiful scenic spot where the Arakawa River flows. In this area, rock terraces stretching 5 km long look as if they are covered with tatami mats.

These rocks are called “Nagatoro-shiki metamorphic rocks” and are among the oldest rocks in Japan. This rock provides important information about the history of the earth and the formation of Japan, and is the subject of much research.

In 1924, it was designated as a national scenic beauty and natural monument.

Here, visitors can enjoy a boat ride while admiring the rock pavements and strange stones. The boat ride is 5 kilometers long and allows visitors to fully enjoy the beauty of nature.

Nagatoro Gorge is a beautiful gorge located in the upper reaches of Arakawa River in the Chichibu region of Saitama Prefecture. It is about 6 km long and has long been called “Nagatoro” because of its long stretches of rock pavements and gently flowing river (瀞).

It was designated as a national scenic beauty and natural monument in 1924, and the area includes the riverbanks of Nagatoro-cho and Minamino-machi. It is also part of the Saitama Prefectural Nagatoro Tamayodo Nature Park.

In this area, crystalline schist formed deep underground is exposed on the ground surface, providing a rare glimpse into the interior of the earth. For this reason, it is also called the “Window of the Earth.

The area is famous for its line rafting and rock formations, and offers canoeing, rafting, camping, and other activities.

Chichibu’s specialties include pork marinated in miso (a Chichibu specialty) and shaved ice made from natural ice. In the fall, visitors can also enjoy apple picking nearby.

The topography of the area has the following characteristics:

Iwadatami: A metamorphic rock belt called the Sambagawa Metamorphic Belt is exposed on the ground surface, with smooth walls extending in a north-south direction. It is thought to have been formed by rocks peeling off along the cracks.

Chichibuseki-heki: Steep cliffs formed by erosion by the Arakawa River, especially on the opposite bank near Iwadatami. It is named after the iron in the black schist that seeped out and oxidized, turning it red.

Pothole: A pothole is a mortar-like depression in the riverbed formed by gravel and pebbles trapped in the concavity of the rocky riverbed when the rapids of the Arakawa River create an eddy at its bends. Some of the larger ones are large enough to hold an adult.

Tora-iwa (tiger rock): A crystalline schist about 15 meters wide with a surface pattern that looks like a tiger’s fur. The rock is called stilpnomelenic schist and contains brown stilpnomelen, white quartz, calcite, and emerald feldspar. Folds can be seen deep underground.

These landforms are interesting features that provide a glimpse into the history and geology of the earth.