English edit

Etymology edit

From micro- +‎ tephra.

Noun edit

microtephra (uncountable)

  1. (geology, paleontology) Microscopic deposits of tephra.
    • 2011, Chris Stringer, The Origin of Our Species, Penguin, published 2012, page 45:
      This microtephra may be ejected into the upper atmosphere and travel for many thousands of miles […].