Pillow Lava
The dark green rocks along the road here are pillow lava formations, formed about 100 million years ago. Geologists believe that the bulbous, usually spherical lobes of pillow lava can only form in the deep sea, where the lava flow is halted by low temperatures and high water pressure. They are created when lava from a volcanic eruption breaks through the hardened surface of the sea floor and oozes out like paste squeezed from a tube, then forms a crust as it quickly cools. The process repeats itself to produce steep mounds of pillow-like rock formations like this one, which gradually rise from the ocean floor as tectonic plates collide. The pillow lava formations here, 100 meters above sea level, are vivid testimony to the power of the geological forces that created this part of Tokunoshima Island.