Figure 4

(A) The Zao volcano's crater lake is surrounded by a 3-m layer of white ash, which also covers the old crater. The blackish material present is scoria derived from the scoria cone. (B) The upper and lower lava flows of 0.3 Ma are accompanied by the 100-m Kaerazuno-taki waterfall. The sequence includes white altered lavas and pyroclastics, followed by block-colored, unaltered scoria cone at the summit. The Zao-Kawasaki Scoria (Za-Kw), dating back to 0.03 Ma, originated from this scoria cone. (C) Aoso-yama summits are primarily composed of lava, while the Magaritake quarry outcrop displays its lateral facies. (D) The quarry consists of 15-m basaltic pyroclastics, followed by 20-m dacitic pyroclastics, and finally 30-m rhyolitic pyroclastics which have weathered to a reddish color. The reddish layer at the top serves as the source of the Aoso-Tsubonuma Pumice 1 (TbP1). (E) The Aobayama II higher terrace, located near the "Nanno Terrace" in Aobayama, is observed at Tohoku University. The sequence from bottom to top includes weathered gravels, white fluvial silt, reddish "Koeji Ash", and the Adachi-Medeshima Pumice (Ac-Md). (F) The higher terrace can be found at the top of a 150-m outcrop and consists of 15 m of weathered gravels. The thick white pumice tuff belongs to the upper Miocene Nashino Formation. The observation was made from the lower terrace, with the present Natori-gawa River in the Akiu-Baba area. Sight seeing point named “white rock”. (G) Reddish loam is intercalated with a 50-cm layer of white Aoso-Tsubonuma Pumice 1 (TbP1), overlain by the 1.5-m of white Adachi-Medeshima Pumice (Ac-Md). In this photo, the contact with the basement rocks of the lower Miocene Takadate Formation, basaltic tuff breccia, can be seen. The outcrop is located at the top of the Tsubonuma quarry. (H) The Sendai Kamimachi terrace consists of a 1-m layer of lower gravels and a 1-m layer of upper loam. It unconformably overlays tilted black basaltic lava of the Takadate Formation and stratified shallow marine sandstone and conglomerate of the middle Miocene Moniwa Formation. This terrace is relatively downstream of the Natori-gawa River.