Ōu Mountains

Ōu Mountains
奥羽山脈 Ōu-sanmyaku
A section of the Ōu Mountains near Kōriyama, Fukushima
Highest point
Peak	Mount Iwate (Iwate Prefecture)
Elevation
Dimensions
Length	North-South
Width	East-West
Geography
Country	Japan
States	List Aomori Prefecture Akita Prefecture Fukushima Prefecture Iwate Prefecture Miyagi Prefecture Yamagata Prefecture
Region	Tōhoku
Range coordinates
Geology
Orogeny	Island arc
Type of rock	Volcanic

The Ōu Mountains (奥羽山脈, Ōu-sanmyaku) are a mountain range in the Tōhoku region of Honshū, Japan. The range is the longest range in Japan and stretch 500 km (311 mi) south from the Natsudomari Peninsula of Aomori Prefecture to the Nasu volcanoes at the northern boundary of the Kantō region. Though long, the range is only about 35 kilometres (22 mi) wide. The highest point in the range is Mount Iwate, 2,038 metres (6,686 ft).

The range includes several widely known mountains: Hakkōda Mountains, Mount Iwate, Mount Zaō, Mount Azuma, and Mount Adatara.

Naming

These mountains previously formed the boundary between historical provinces of Mutsu (陸奥国) and Dewa (出羽国). The kanji for the name of the mountain range was created from one kanji of the two provinces, 奥 and 羽, respectively.

Geology

The Ōu Mountains began to form in the Pliocene. They sit over the middle of the inner arc of the Northeastern Japan Arc. This is the result of the Pacific Plate subducting under the North American Plate. A chain of Quaternary volcanoes along the range forms the volcanic front.