"Senjojiki" received its name from the small fissures running up and down the length of the wave-cut platform that make it appear as though a tatami mat was laid across the surface. Fossils of bivalves and conch shells, and round stool-like stones called nodules created by erosion from waves are scattered across the flat seashore. The nodules are hardened like concrete from the calcium carbonate produced by seashells. "Uma no Se" is a land form shaped like a horse’s back that was created due to the earth moving and shifting the stratum so that it protruded from the surface. Beyond that lies a dike that was created from magma that penetrated near the earth’s surface. Lastly, fossils of shells formed into the shape of a cute heart called "Happy Shells" are dotted along the surface of Senjojiki. Senjojiki became designated as a national natural monument on March 25th, 1932.
266 Matsubaracho, Hamada, Shimane (in the vicinity)