Iwami Tatami-ga-ura

Overview

Iwami Tatami-ga-ura is a coastal scenic area in Hamada City, Shimane Prefecture, designated as a national natural monument. It offers a rare glimpse into a geological formation created by the uplift of a seabed approximately 16 million years ago, making it a site of immense geological significance. The area was long known as "Toko-ura," a scenic spot, but the 1872 Hamada earthquake caused a seabed uplift of about 30cm, resulting in the present landscape combining Senjōjiki and a steep cliff. While some theories suggest an uplift of about 1 meter, this is based on research conducted over 40 years after the earthquake, hence its credibility is low. The rock bed comprising Senjōjiki is shelf-like due to wave erosion, known as a wave-cut platform, and consists of sandstone layers. This sandstone contains exceptionally well-preserved fossils of mid-Miocene shellfish, driftwood, and whale bones. At the center of Senjōjiki lies a rocky outcrop called "Uma no Se" (Horse's Back). This rock reef, originally located on the coast, was exposed by the earthquake, clearly revealing layers of sandstone and conglomerate. The conglomerate layer, originally buried under the seabed, was exposed by the same earthquake. Numerous round stones, like small seats, are scattered across Senjōjiki. These are called nodules, formed when the rock bed itself rose during the aforementioned earthquake. They are arranged regularly in 11 rows, following the strata. These nodules are cemented together like concrete due to the calcium carbonate from the seashells. This is an extremely rare phenomenon nationwide and a distinctive feature of Tatami-ga-ura, possessing immense geological value. In 2007, the theft of five nodules was discovered, and a theft report was filed with the Hamada Police Station. A 20-meter-high cliff develops behind the coast, where the intersection of strata is prominent. A sea cave is also present, with a Jizo Bosatsu (statue of Jizo, a Buddhist deity) placed inside. There is also a place called Saino Kawara (a place where spirits of the dead reside in Buddhist belief) along the way. The unusual rock formations of Inujima (Dog Island) and Neko-jima (Cat Island) float offshore. Iwami Tatami-ga-ura is a top scenic spot in the city, developed as a tourist destination, attracting many anglers and swimmers. The scent of the Iwami Tatami-ga-ura coast has been selected as one of the "Fragrant Landscapes 100 Selections" by the Ministry of the Environment.