Makinohara

This alluvial plateau stretches between the downstream of the Oi River and the Kikugawa River in central Shizuoka Prefecture. It was once an uplifted alluvial fan of the Oi River. The height of the plateau is about 270 meters above sea level at Andabara in Shimada City in the north, gradually decreasing to 50 meters above sea level at the uplifted marine plateau of Omaezaki at the southern end. The plateau has been dissected by eroded valleys from the surrounding area, giving it a dendritic form, and it has many local names such as Okadahara, Gongenhara, Chojahara, and Asahinabara. The surface is made up of river-formed Makinohara gravel layers, but at the southern end it becomes a marine gravel layer. Currently known as a large tea plantation, it was once covered by vast wilderness, and the existence of horse pastures and pastures is said to be the origin of the place name. The development of the tea plantation began in 1869 (Meiji 2) with the settlement of samurai who were former retainers of the Tokugawa clan and laborers from Kawagoe, Oigawa, and with the addition of land reclamation by nearby farmers, the area developed into a tea production area. Currently, the tea plantation covers an area of ​​about 5,000 hectares, and the National Agriculture and Food Research Organization's Vegetable and Tea Industry Research Institute and Shizuoka Prefectural Agriculture and Forestry Technology Research Institute's Tea Industry Research Center are advancing cultivation and tea processing techniques. In 2002 (Heisei 14), the Nagashima Dam was completed upstream of the Oigawa River, and it began to be used to regulate the Oigawa River's floods and as agricultural irrigation water for the plateau.

[Kitagawa Mitsuo]

Source: Shogakukan Encyclopedia Nipponica About Encyclopedia Nipponica Information | Legend

静岡県中部、大井川下流と菊川の間に広がる洪積台地。かつての大井川の隆起扇状地。台地面の高さは北の島田市の安田原(あんだばら)で標高約270メートル、南へ緩やかに低まり、南端の御前崎(おまえざき)の隆起海食台では標高50メートルになる。台地面は周辺からの侵食谷によって開析され、樹枝状の形態をもち、岡田原、権現原、長者原、朝比奈原(あさひなばら)など局地的名前も多い。表面は河成の牧ノ原礫(れき)層が堆積(たいせき)しているが、南端では海成の礫層となる。現在は大茶園として知られるが、かつては原野が広がり、馬牧や牧野の存在が地名の起源ともいわれる。茶園の開拓は1869年（明治2）徳川家旧臣の士族や大井川川越人夫の入植によって始まり、近在の農民の開墾も加わり産地化が進んだ。現在約5000ヘクタールの茶園が広がり、農研機構野菜茶業研究所と静岡県農林技術研究所茶業研究センターが栽培・製茶技術を進めている。2002年（平成14）大井川上流に長島ダムが竣工、大井川の洪水調節とともに、台地の農業用水として利用されるようになった。

［北川光雄］

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