About
As you travel along National Route 299, which winds through the mountains of Kanna Town in Gunma Prefecture, you will come upon a rock wall known as Sebayashi's Ripple Marks (Sazanami-iwa), standing 15 meters high and 11 meters wide. Etched into this rock face are traces of waves formed about 120 million years ago during the Cretaceous Period. At that time, this area was under the sea, and waves breaking on the sandy shore left patterns in the sand, which eventually fossilized over the ages. These ripple marks were designated as a natural monument of Gunma Prefecture in 1965 (Showa 40).
However, this rock wall held an even more astonishing secret. In 1985 (Showa 60), researchers discovered that depressions on the upper part of the ripple marks were actually dinosaur footprints. This was the first confirmed discovery of dinosaur footprint fossils in Japan, prompting the then Nakazato Village (now Kanna Town) to proclaim itself the "Dinosaur Kingdom." On the upper left of the rock face, there are two footprints from a large bipedal dinosaur, while from the upper right to lower left, a succession of smaller dinosaur footprints can be seen. These footprints are proof that dinosaurs once walked this land.
The stratum here belongs to a mountainous rift zone that runs for 40 kilometers along Route 299, from Ogano Town in Saitama Prefecture, over the Shigasaka Pass, through Kanna Town and Ueno Village in Gunma, across the Jukkoku Pass on the Josin border, all the way to Sakuho Town in Nagano Prefecture. This rift zone is a region where strata from the early Cretaceous Period spread, and many dinosaur footprints and fossils have been discovered.
Near the Sebayashi Ripple Marks is the Kanna Town Dinosaur Center, which exhibits dinosaur fossils and models. It also holds events such as fossil excavation experiences, giving visitors a sense of ancient romance. If you visit this place, you will surely feel the breath of dinosaurs from more than 100 million years ago.