A national natural monument, To no Hetsuri consists of tower-shaped cliffs overlooking a river. Hetsuri is a word meaning “a cliff overlooking a river” or “a steep slope” in the local dialect. According to Genkai, the first modern Japanese dictionary, the verb “hetsuru”, from which the noun “hetsuri” derives, means the same as “kezuru” (to sharpen) and there are examples in which “hetsuri” is interpreted as a palisade or a steep road along a river. The strange-shaped rocks are made of various types of tuff in the Neogene strata (formed around 28 million years ago) and feature deep cracks along the vertical joints. The alternating strata of different types of material include relatively soft strata, which have been eroded by rain and wind, resulting in distinctive and oddly shaped rocks that resemble a forest of towers. Each of these tower-like rocks has its own name, such as Eagle Tower, Hawk Tower, Lion Tower, House Tower, Turret Tower, Nine-ring Tower, Elephant Tower, Goma (fire ritual) Tower, Eboshi (tall hat worn by male aristocrats in Heian Period) Rock, Folding Screen Rock, Stage Rock, and Sumo Arena Rock.