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The outcrop at the Tatsuishi coast. The yellow-color stratum is the debris flow deposit derived from the old Unzen Volcano. The ejecta of middle Unzen Volcano are coverd with it by unconformity. |
Tatsuishi
The Kuchinotsu group is deposited between 2.5 million and 700,000 years ago. Activity on Unzen Volcano began approximately 500,000 years ago. The center of this activity is thought to be the area from the present day Obama to Unzen. Unzen Volcano grew and its foothills began to spread approximately 300,000 years ago and extend as far as the Minami Shimabara area (Otsuka et al., 1995). On this coast can we see the debris flow of Unzen Volcano, which covered the Kitaarima formation in unconformity.