Sea of Japan Exhibit: Overview

Shimane’s natural world is deeply linked with the geological and biological history of the Sea of Japan. Exhibits in this hall focus on the sea’s formation, the prehistoric life that inhabited it, and aspects of modern-day ecology.
The Sea of Japan was formed around 25 million years ago, when Japan was still part of the Eurasian supercontinent. Volcanic activity and tectonic shifts began pulling the easternmost edge of the continent away, and the land between sank in on itself, forming a lakebed. As the stretching process continued, ocean water flowed in through low points to the north and south, and the lake became a sea.
This exhibit includes rock and mineral samples from various stages of the sea’s formation, including green tuff, a porous, green-hued volcanic rock formed from compressed volcanic ash and debris; aragonite, a crystalized form of calcium carbonate that forms in marine environments; and many samples of fossilized sea life. The fossils range from small shellfish to the reconstructed skeletons of large aquatic creatures, such as the hippo-like Desmostylus and sea-lion-like Allodesmus. The exhibit is also home to King Ryanko, the only taxidermic specimen of an adult male Japanese sea lion, a more recently extinct species of the region.