Yamauchi Basin
The spacious farming center of the islands
This area in central Fukue Island is broad and flat, with regularly spaced, rectangular rice fields that make it the granary of the Goto Islands. The formation of the area, however, was very much determined by the same forces that created the rocky lava shorelines and rugged islands.
To the west of the Yamauchi Basin are Mt. Nanatsudake (431 m) and Mt. Tetegadake (460 m). Like the rest of the Goto Group, these mountains are hornfels—sedimentary rocks metamorphozed and hardened by the heat of the magma below. Crustal deformations some 15 million years ago caused faulting and cracking of the area. Lava flow from an eruption some 741,000 years ago dammed an ancient river, and a lake was formed. Volcanic ash and sediments accumulated in the lake, creating the conditions responsible for today’s fertile farmlands. Hornfels are tough and do not erode easily, so rainwater runs off them and into the rivers, further improving farming conditions.