Sebayashi Formation, Geological formation in Gunma Prefecture, Japan.
The Sebayashi Formation is a geological layer in Gunma Prefecture composed of alternating bands of sandstone and shale. These deposits also contain thicker conglomerate sections distributed throughout the formation.
This rock formation originated during the Early Cretaceous period roughly 125 to 100 million years ago, when the region was covered by a shallow sea. It holds an important collection of fossils that provide clues about life during that ancient time.
Scientists and researchers from Japanese institutions regularly conduct studies at the site to document prehistoric life patterns in the region.
This formation sits in the mountains south of Kannauri and can be reached via Route 299, which connects to the nearby city of Chichibu. Visitors should bring weather-appropriate clothing and be aware of rough mountain conditions.
The rock walls display preserved wave patterns from when the area was underwater, and contain the first dinosaur footprints discovered in Japan. This combination makes them a rare window into early dinosaur history in East Asia.
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