Isawa alluvial fan

Japanese: 胆沢扇状地 - いさわせんじょうち

…A river that flows through the southern part of Iwate Prefecture. It originates at Mt. Omori (1,150m) in the Ou Mountains, flows eastward, creates the magnificent Isawa alluvial fan, and empties into the Kitakami River at the southern end of Kanagasaki Town. The main river length is 49km. …

From the Kitakami Basin

…On the west side of the alluvial lowlands south of Morioka City, higher river terraces and alluvial fans have developed, continuing to the fault cliffs of the Ou Mountains. Among them, the Isawa alluvial fan and the Rokuhara alluvial fan are famous, and in the early 9th century, Isawa Castle and Shiwa Castle were built at the ends of these alluvial fans and plateaus, and together with the alluvial lowlands, they became bases for the development of the Tohoku region from an early stage. In the Edo period, the Kitakami River was used as a shipping route, and the Oshu road also ran through the basin from north to south, so the major urban clusters of today, such as Ichinoseki, Mizusawa, Iwayado (Esashi City), Kurosawajiri (Kitakami City), Hanamaki, Hizume (Shiwa Town), and Morioka, developed from post towns and river port settlements along the road. …

*Some of the terminology that refers to the Isawa alluvial fan is listed below.

Source | Heibonsha World Encyclopedia 2nd Edition | Information

Japanese:

…岩手県南部を流れる川。奥羽山脈の大森山(1150m)に源を発し，東流してみごとな胆沢扇状地をつくり，金ヶ崎町南端で北上川に注ぐ。幹川流路延長49km。…

【北上盆地】より

…盛岡市以南の沖積低地の西側は，一段と高い河岸段丘や扇状地が発達し，奥羽山脈の断層崖に続いている。中でも胆沢（いさわ）扇状地や六原扇状地は有名で，9世紀初めにはこの扇状地や台地の末端に胆沢城や志波（しわ）城が築かれ，沖積地とともに早くから東北開発の拠点となった。また，江戸時代の北上川は船の交通路として利用され，さらに奥州道中もこの盆地を南北に通じていたため，現在の一関，水沢，岩谷堂(江刺市)，黒沢尻(北上市)，花巻，日詰(紫波（しわ）町)，盛岡などのおもな都市群は，街道筋の宿場町や河港集落を母体として発展した。…

※「胆沢扇状地」について言及している用語解説の一部を掲載しています。

出典｜株式会社平凡社世界大百科事典第２版について | 情報

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