Basalt Formation: Genbudo, Japan

Basalt formation in Genbudo cave

Basalt is a type of igneous, or volcanic rock which underlies most of the earth's surface. It is commonly used in construction for pavement, cobblestones, and in making statues. Its shape when hardened indicates the process and environment by which it was cooled. In the cave above, the basalt formed in polygonal shapes, but other basalt formations can be columnar when cooled more rapidly.




Learn more about basalt.