Shiranuka Hills

Hills in southeastern Hokkaido. Extending from the western part of the Kushiro Regional Subprefectural Bureau to the eastern part of the Tokachi Regional Subprefectural Bureau, with an elevation of 200 to 400 meters. It borders the Kushiro Plain and Tsurui Hills to the east, a volcanic region to the north, the Tokachi Plain to the west, and the Pacific Ocean to the south. Erosion progressed from the end of the Tertiary Period to the beginning of the Quaternary Period, and the terrain became flat for a time, after which the ground rose and erosion resumed. The geology is dominated by Paleogene layers, with Neogene layers distributed on the eastern and southern fringes. The Akan, Shoro, Charo, and Onbetsu rivers run parallel to each other on the southeastern side, flowing southeast into the Pacific Ocean, and flat areas continue in strips along the river valleys. Dairy farming and forestry were carried out by turning the river valleys and some of the hills into pasture. They were part of the Kushiro coalfield, but coal mines such as Yubetsu, Shoji, Kamicharo, and Shakubetsu were all closed by 1970 (Showa 45).

[Furukawa Shiro]

Source: Shogakukan Encyclopedia Nipponica About Encyclopedia Nipponica Information | Legend

北海道南東部の丘陵。釧路(くしろ)総合振興局管内の西部から十勝(とかち)総合振興局管内の東部に広がり、標高200～400メートル。東は釧路平野、鶴居(つるい)丘陵に、北は火山地域に、西は十勝平野に接し、南は太平洋に臨む。第三紀末から第四紀初めにかけ侵食が進み、いったん平坦(へいたん)な地形に変わったのち地盤が上昇し、侵食が復活した。地質は古第三紀層が大部分を占め、東と南の周縁部に新第三紀層が分布する。南東側を阿寒(あかん)、庶路(しょろ)、茶路(ちゃろ)、音別(おんべつ)の諸河川が並行して南東流して太平洋に注ぎ、河谷に平地が帯状に続く。河谷と一部丘陵の牧草地化による酪農や林業が行われた。釧路炭田の一部をなしたが、雄別(ゆうべつ)、庶路、上茶路(かみちゃろ)、尺別(しゃくべつ)などの炭鉱は1970年（昭和45）までにすべて閉山した。

［古川史郎］

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