Hita Basin

A fault basin in the western part of Oita Prefecture, stretching 16km from east to west and north to south. The main and tributaries of the midstream Chikugo River have formed river-eroded hills such as Higuma, Tsukikuma, and Hoshikuma, giving the area the name Mikumagawa River, and the city of Hita facing this has earned it the name Suigou Hita. It is surrounded by mountains 300m high, and the area is part of the Yaba-Hita-Hikosan Quasi-National Park. It is said to have been drained by the inflow of Aso lava, and the bottom of the alluvial basin at an altitude of about 80m is rice paddy fields, the lava plateau at an altitude of 100-150m is ordinary fields, mulberry fields, and orchards, and the surrounding mountain areas are forests of pine, cedar, and other trees. In addition, bronze swords and bronze spears have been excavated from the plateau, and ancient tombs are distributed throughout the area. The districts of Arita, Watari, and Ishii in the Wamyōshō were centered on the eastern, northern, and southern plateaus, respectively, which indicates that the plateau was opened up early.

[Shunichi Kaneko]

Source: Shogakukan Encyclopedia Nipponica About Encyclopedia Nipponica Information | Legend

大分県西部にある、東西・南北各約16キロメートルの断層盆地。筑後川(ちくごがわ)中流の本・支流が網流し、日隈(ひぐま)、月隈(つきくま)、星隈(ほしくま)などの河食残丘をつくり、三隈川(みくまがわ)の名が与えられ、これに臨む日田の市街は水郷日田の称を有する。周囲は高さ300メートル級の山に囲まれ、一帯は耶馬日田英彦山国定公園(やばひたひこさんこくていこうえん)の一部となる。阿蘇(あそ)溶岩の流入で排水されたといわれ、高度80メートル前後の沖積盆地底は水田、高度100～150メートルの溶岩台地上は普通畑・桑園・果樹園、周辺山地は松・杉などの森林になっている。なお、台地上には銅剣・銅鉾(ほこ)の出土と、古墳の分布があり、『和名抄(わみょうしょう)』の在田(ありた)、曰理(わたり)、石井(いしい)の各郷(ごう)はそれぞれ東部、北部、南部の台地を中心とし、台地が早く開けたことを物語る。

［兼子俊一］

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