It goes without saying that we live on top of solid earth. Now, around 30 percent of the ground in Okinawa is covered by the limestone rocks in front of you.
Look closely at the stone. Can you discern the fossilized shellfish, coral, and foraminifera? Why are so many sea creatures trapped inside? That’s because Ryukyu limestone is composed of coral reef residue and other submarine sediments dating back to anywhere between about 100,000 to 1,300,000 years ago. These ancient reefs have risen from the sea as the limestone you see now.
Mankind first traversed the Ryukyu Islands 30,000 years ago. Since then, their inhabitants have skillfully harnessed its limestones, among other things. The stone walls that encircle traditional Ryukyu houses are one such example. Also, many of the walls in traditional Okinawan castles (known as “gusuku”) include limestone bricks. Ryukyu limestone is soft compared to other minerals, making it easy to process. As a matter of fact, this museum is modeled after a traditional gusuku, and its outer wall has also incorporated limestone.
It can be said that Okinawa’s abundance of springwater is also thanks to limestone. Though water can easily flow through it, the same cannot be said for the layer of kucha clay sitting beneath that limestone. As a result, rainwater seepage accumulates over the clay layer until it gushes out. The overflow has supported life across southern Okinawa, Miyako Island, and the other limestone islands.