The city of Itoigawa is located at about the centre of the Honshu Island, the main island of arc-form Japanese archipelago at the NW corner of the Pacific Ocean. The city meets the Japan Sea in the north, where mountains of Japan Alps sink into the Sea, while on the south are high mountains.
“A department store of geology” is a word simply but precisely expressing the Itoigawa Geopark. Runs at the centre of the Itoigawa Geopark is “the Itoigawa Shizuoka Tectonic Line” separating the area to east and west halves. In the west are Mesozoic and Paleozoic rocks composing Inner Zone of SW Japan while in the east is Neogene System of Fossa Magna. Quaternary strata cover plains and hills of both east and west areas. Thus age of the rocks within Geopark span over 500 million years.
Due to differential uplift movements of the whole area since the beginning of Quaternary, the lands covers from sea level to the top of the Japan Alps (nearly 3,000m high), with corresponding wide varieties of geology and topography, as well as richness in plants and animal kingdoms. Now you see the geology has strongly influenced history, culture, and life of people of the Itoigawa Geopark.
Aerial View of the Itoigawa Geopark
looking south from over the Japan Sea
Attractions of Itoigawa Geopark
The whole city (746.24km2) is designated as the Geopark. To enjoy many places of interest, altogether 24 areas are arranged as “Geosite” in the order of ease of understanding to the visitors. Besides each Geosites has many “Geo-points”, where you can observe specials of each Geosite.
Let’s select some Geosites for example. At “Itoigawa-Shizuoka Tectonic Line and Salt Trail Geosite” awe-inspiring geology and connecting human history and culture can be enjoyed.
Itoigawa city is situated at the northern terminus of the great fault line, the Itoigawa-Shizuoka Tectonic Line geologically separating North-Eastern Japan and South-Western Japan. This also said to be the border of the North American and Eurasian plates, and the Fossa Magna, a geological U-shaped trench that runs from Itoigawa to the Izu peninsula on the Pacific Ocean.
Along the fault, being developed was a trading route called “Salt trail” by which salt and sea products were transported from the sea to the mountainous area. As a result of avoiding a violent Himekawa River, people found the safe route along the fault line. Up until now the fault line separates not only Geological features of Japan but also the culture of the country in many aspects like special food eaten in New Year, dialect and so on.
The other example is the “Kotakigawa Jade Gorge” Geosite. When someone talking about the Itoigawa Geopark, what they can’t forget is the oldest Jade culture in the world. Jade, a representative gemstone of the East, is a products of crustal movement during the age of continent and island arc. Jade was formed at depths of subducting plate in Paleozoic, brought up to the surface by tectonic movements and then dispersed by rivers and sea.
People in Itoigawa used to collect jade and use as ornaments. Until now processed Jades has been found from the archeological site of about 2,600 years B.C. within the Geopark. It is known that these were distributed all over Japan and some had even reached Korean Peninsula.
Still active Mt. Yakeyama volcano in “Yakeyama Geosite”
Those are just a few example of intimately intertwined relationship of man and nature. Following theme are also found in other geosites within the Itoigawa Geopark.
-Natural disasters (Volcanoes, earthquake, landslide and debris flows) and fighting human histories.
-Various topography corresponding to from 0 m to 3,000 m high
-Living in deep snow country and natural gas utilization, hot springs
-Submarine volcano and marine culture
In Itoigawa Geopark typical life, history and culture of people on the island arc area retained and those can vividly be shown to the world. To find out more about Itoigawa Geopark, simply visit and experience still active earth under your feet.
Itoigawa Geopark Promotion Office (Itoigawa city office)