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Field Photographs of the Rio Blanco Tephra Deposit



A) The Rio Blanco tephra is a well-sorted, lithic-poor lapilli airfall deposit that ranges in thickness from a few centimeters to greater than 20 m near source. The pumices contain phenocrysts of plagioclase, orthopyroxene, and rare hornblende.

B) View looking west from the boundary of the dead zone. The Rio Blanco tephra deposit blankets most of the ridgetops in the dead zone but has been eroded from the valleys. The deposit rests unconformably above all other deposits in the dead zone.

C) View of proximal deposits of the Rio Blanco tephra 1.2 km SW of the Active Crater. The deposit exceeds 20 meters in this area and is extremely poorly sorted, containing blocks and bombs up to a meter in diameter.

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