徳島市中徳島町で掘削された第四系ボーリングの記載（速報）

A 80 m-long borehole core (TK-B-1) drilled in the Tokushima Plain was examined. Based on the sedimentary facies, volcanic ash layers, pollen fossils and radiocarbon dates, this core was divided into the following 13 units. Unit 1 is a metamorphic rock that forms the base of the Tokushima Plain. Units 3 to 8 are Pleistocene and consist of marine and fluvial strata. Units 12-10 are considered to be Alluvium based on radiocarbon dates, and K-Ah tephra found in Unit 11. In Unit 10, we found a volcanic glass concentration derived from AT tephra, but the concentration is a possibility of rework. We intend to reveal the subsurface geological structure of the Tokushima Plain based on the database of borehole data, lithologic stratigraphy, volcanic ash stratigraphy and biostratigraphy.

令和2年度沿岸域の地質・活断層調査研究報告
Annual Report of Investigations on Geology and Active Faults in the Coastal Zone of Japan (FY2020)
出典：産総研地質調査総合センターウェブサイト（https://www.gsj.jp/researches/project/coastal-geology/sokuho/r2sokuho.html）