On the Arasaki Coast of the Miura Peninsula in Kanagawa Prefecture, Japan, there are striped strata with a crisp pattern of black and white. Two different colors of volcanic ash fall alternately to form such a formation. The whitish layer is a rhyolitic volcanic ash layer. The grain size is finer than sand and is classified as silt. On the other hand, the black layer is a basaltic volcanic ash layer, which has coarser grain size than the white layer and is classified as sand to gravel. Since there are more gravels in the black layer, it may be more appropriate to call it a scoria layer rather than a volcanic ash layer. The black layer was more resistant to wave erosion than the white layer, and the black areas were convex.
Photo story: Arasaki Coast, Miura Peninsula, Kanagawa
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渡邉克晃
写真家。地球科学コミュニケーター。東京大学地球生命圏科学グループ、原子力規制庁技術基盤グループなどで地球科学分野の研究に従事し、3年間の教職を経て、2020年よりサイエンスコミュニケーション事業を開始。博士(理学)。サイバー大学TA。