Fudo-gan
Three monoliths stand at different elevations on Mt. Kamou (389 m), forming an impressive tableau that can be seen from the surrounding countryside. These enormous stones are the Fudo-gan, named after the Buddhist deity Fudo Myo-o, also known as Acala. During the Heian period (794–1185), mountain ascetics worshiped and practiced austerities around the monoliths. A trail leads up the mountainside and around the Fudo-gan, passing a shrine dedicated to Fudo Myo-o.
The tallest of the Fudo-gan has a height of 80 meters and a base circumference of 100 meters. A close examination reveals the monoliths are actually composed of countless small rocks ranging from 5 millimeters to 50 centimeters in diameter. This rock is called gabbro and originally formed from hardened lava more than 500 million years ago in the Paleozoic era, before the existence of the Japanese archipelago. The gabbro became submerged in sea water, fragmenting and eroding over time into rounded pebbles and sand, which then consolidated into one large structure due to massive pressure.