Ikoma Mountains - Ikomasanchi

A long, narrow mountain range that runs north to south on the border between Nara Prefecture and Osaka Prefecture. It is about 35 km north to south and 5 km east to west. Its main peak is Mt. Ikoma (642 meters), the northern end is the Otokoyama Hills, and the southern end is the Yamatogawa Valley. Beyond the valley is the Kongo Mountains, including the Nijo old volcanic group. Together with this mountain range, it is designated as the Kongo-Ikoma-Kisen Quasi-National Park. The geology is mostly granite, and its origin has traditionally been thought to be a tectonic plateau (tilted land mass), but in recent years the folded mountain theory has become more popular. The western slope facing the Osaka Plain is a steep fault scarp covered with trees and bushes, and housing development can be seen along the slope transformation line. The eastern slope facing the Nara Basin is gentle, and farmland has been opened up along the valley, with residential development thriving. Vineyards spread from the foot of the mountain to the mountainside on the southern slope of the Yamatogawa Valley. On the eastern slope of the main peak, Mt. Ikoma, is Hozan-ji Temple, affectionately known as "Ikoma's Shoten-san," and a temple town has developed around the foot of the mountain. In the southern part of the mountain range is Mt. Shigi (437 meters), and on its southeastern slope is Chogosonshi-ji Temple, known as "Shigisan's Bishamon-san." The Hanna Expressway runs between Osaka and Nara, and the Shigiikoma Skyline, which passes by the top of Mt. Ikoma, branches off near Tatsuma Pass. The Kintetsu Nara Line also connects Osaka and Nara through the Shin-Ikoma Tunnel.

[Ichiro Kikuchi]

Source: Shogakukan Encyclopedia Nipponica About Encyclopedia Nipponica Information | Legend

奈良県と大阪府との境界を南北に走る狭長な山地。南北約35キロメートル、東西約5キロメートル。主峰は生駒山（642メートル）、北端は男山(おとこやま)丘陵、南端は大和(やまと)川渓谷で、さらに渓谷を越えて二上(にじょう)旧火山群を含む金剛(こんごう)山地が続き、この山地とともに金剛生駒紀泉国定公園に指定されている。地質は大部分が花崗(かこう)岩で、成因は従来、地塁山地（傾動地塊）とされてきたが、近年は褶曲(しゅうきょく)山地説が有力となっている。大阪平野に臨む西斜面は急傾斜の断層崖(がい)で、樹木や藪(やぶ)で覆われ、傾斜変換線に沿って宅地化がみられる。奈良盆地側の東斜面は緩傾斜で、谷に沿って耕地が開け、住宅地の造成が盛んである。大和川渓谷の南斜面は山麓(さんろく)から山腹にかけてブドウ畑が展開する。主峰生駒山の東山腹には「生駒の聖天(しょうてん)さん」で親しまれる宝山寺(ほうざんじ)があり、山麓にかけて門前町が発達する。山地南部には信貴山(しぎさん)（437メートル）があり、その南東山腹に「信貴山の毘沙門さん(しぎさんのびしゃもんさん)」で知られる朝護孫子寺(ちょうごそんしじ)がある。大阪―奈良間の横断路として阪奈道路が走り、途中竜間(たつま)峠付近から、生駒山頂を経由する信貴生駒スカイラインが分岐する。また、近畿日本鉄道奈良線が新生駒トンネルを通して大阪―奈良間を結ぶ。

［菊地一郎］

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