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Tenjosan Tephra

• Tephra
• Holocene (AD838)

• Sedimentary facies: Pyroclastic surge deposit
• Lithofacies: Biotite rhyolite volcanic ash
• Sedimentary structures: Cross stratification

• Source: Tenjosan volcano
• Thickness: 20 - 100 cm
• Upper limit: Unconformity (Mukaiyama Tephra)
• Lower limit: Unconformity (Shikinejima volcano)

• Distribution: Shikinejima island, Niijima city, Tokyo

• Isshiki (1987) Geology of the Nii Jima District, Quadrangle Series, Scale 1:50,000, Geological Survey of Japan, 85p. (in Japanese with English abstract 3p.)