Kii Mountains

A mountain range that makes up the Kii Peninsula in the southern part of the Kinki region. It belongs to the Western Japan Outer Zone south of the Median Tectonic Line that connects the Kino River and the Kushida River, and the strata are arranged in a belt from north to south, with the Paleozoic, Mesozoic, and Tertiary Oligocene layers. The topography is also influenced by the arrangement of the strata, and a folded mountain range runs east to west parallel to the direction of the Median Tectonic Line, but in the central part of the mountain range, three lines run north to south: the Omine Mountain Range, which includes Mount Hakken (1,915 meters), the highest point on the peninsula, Mount Shakagatake (1,800 meters), the Daiko Mountain Range, which stretches from Mount Takami (1,248 meters) to Mount Odaigahara (1,695 meters) to the east, and the Kiwa Mountain Range, which includes Mount Gomadan (1,372 meters) to the west. Due to this influence, the rivers that flow through this area, such as the Kinokawa River, the Arida River, the Hidaka River, and the Tonda River, flow west, while the Kushida River and the Miyagawa River flow east, while the Hiki River, the Koza River, and the Kumano River (Kitayama River, Totsu River) flow south. The mountain range shows the rugged mountain shape of its prime, but there are no prominent peaks and it is isotopic. Mount Odaigahara and Mount Koya have flat summits, and the mountain range as a whole shows the characteristics of an uplifted semi-plain.

[Yoichi Koike]

Source: Shogakukan Encyclopedia Nipponica About Encyclopedia Nipponica Information | Legend

近畿地方南部、紀伊半島を構成する山地。紀ノ川、櫛田川(くしだがわ)を結ぶ中央構造線以南の西日本外帯に属し、地層は北から古生層、中生層、第三紀漸新層と帯状に配列する。地形も地層配列の影響を受け、中央構造線の方向に並行して褶曲(しゅうきょく)山脈が東西走するが、山地中央部では、半島の最高部をなす八剣山(はっけんざん)（1915メートル）、釈迦ヶ岳(しゃかがたけ)（1800メートル）などを連ねる大峰山脈(おおみねさんみゃく)と、その東側の高見山（1248メートル）から大台ヶ原山（1695メートル）を連ねる台高山脈(だいこうさんみゃく)、西側に護摩壇山(ごまだんざん)（1372メートル）などを含む紀和山脈の3列が南北走する。この間を流れる河川もその影響で紀ノ川、有田(ありだ)川、日高川、富田(とんだ)川などは西流し、櫛田川、宮川は東流するが、日置(ひき)川、古座(こざ)川、熊野川（北山川、十津(とつ)川）は南流する。山地は壮年期の険しい山容を示すが、際だった山頂はなく等高性で、大台ヶ原山や高野山(こうやさん)には山頂平坦(へいたん)面があり、山地は全体として隆起準平原の特徴を示している。

［小池洋一］

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