熊野層群とこれを貫くマグマからできた流紋岩（花崗斑岩）の地質境界が露出します。マグマが低角に貫入してできたシート状の火成岩脈です。熊野川の岩壁（四目山）にはマグマの冷却時の収縮による柱状節理が発達し、熊野川の峡谷に特徴的な風景を形づくります。大峯山脈沿いに分布する大峯花崗岩質岩の最も南側の岩体です。

The geological boundary of rhyolite (granodiorite) formed from the Kumano Group and the magma that penetrates it is exposed. It is a sheet-shaped igneous rock vein formed by magma penetrating at a low angle. Columnar joints develop on the rock wall of the Kumano River (Mt. Yotsume) due to the contraction of magma during cooling, forming a characteristic landscape in the Kumano River canyon. It is the southernmost body of Omine granitic rocks distributed along the Omine Mountains.

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うえもり　う 2022/01/20(Thu) 21:40 No.196