Outer Zone

geographical region, Japan

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July 1, 2026

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The Outer Zone is a geographical region within Japan, characterized by a regular arrangement of crystalline schists and Paleozoic, Mesozoic, and Cenozoic formations. This zone is part of the larger Southwestern Region of Japan and is distinguished from the Inner Zone by its more continuous geological structure, except where separated by sea straits. The Outer Zone's geological makeup is a result of warping, a process of bending in the Earth's crust. This region includes mountain groups such as the Akaishi, Kii, Shikoku, and Kyushu mountains.1

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Japan
The major physiographic regions
…by complex faulting, and the Outer Zone, formed by warping. The Inner Zone is chiefly composed of ancient granites, rocks of Paleozoic age (250 to 540 million years old), and geologically more recent volcanic rocks, which are arranged in complicated juxtaposition. The Outer Zone, consisting of the Akaishi, Kii, Shikoku,…
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…by complex faulting, and the Outer Zone, formed by warping. The Inner Zone is chiefly composed of ancient granites, rocks of Paleozoic age (250 to 540 million years old), and geologically more recent volcanic rocks, which are arranged in complicated juxtaposition. The Outer Zone, consisting of the Akaishi, Kii, Shikoku,…
Read More