tephra

plural tephras

1. countableuncountablegeographyThe solid material thrown into the air by a volcanic eruption that settles on the surrounding areas.

   Tephra could encourage phytoplankton blooms that could potentially sequester huge amounts of carbon dioxide

   2020 October 5, Ian Randall, Chemistry World, Royal Society of Chemistry

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   The sky would have darkened with sheer volume of ash, the grapes would have withered upon the vine; misfortune would have fallen with the inexorability of volcanic tephra upon rich and poor alike.

   2004, Richard Fortey, The Earth, Folio Society, published 2011, page 126

   Over a five-year research period, RESET is correlating tephras from their volcanic sources to where they fell in deep ocean and lake sediments, and even further into important archaeological sites in Europe, western Asia and North Africa.

   2011, Chris Stringer, The Origin of Our Species, Penguin, published 2012, page 46