The Slab Stone of Ryūnokawa (Dragon’s River)

  • Modification: 2024/01/10
  • Area: harumaki

This gigantic slab of riverbed rock, large enough for a person to lie sprawled across when the water level is low, synthesises a stunning atmosphere together with the surrounding forest, don’t you think? But… why is it here?

This large slab of rock is of the sedimentary variety belonging to the Hinata Group (a group being a lithostratigraphic unit) often found along Yakushima’s coastline. About 40 million years ago, mud and sand at the ocean floor underwent tremendous pressure at the rifts between ocean plates, eventually across eons forming the bedrock of this island as it was pushed to the surface. Traces of this rock’s history as the bottom of an oceanic rift lingers in its horizontally level shape. Ages and ages ago, in that mud at the bottom of the ocean, lived such species as spoonworms and sand worms—the type that form zoophycos ichnofossils.

How about you try sprawling yourself out across this ancient rock and letting your imagination run away with the primordial history of Yakushima? Just be careful not to slip and hurt yourself while exploring the area!

The Slab Stone of Ryūnokawa



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