Photos - Kristi Wallace

shards

Volcanic ash, or tephra, as seen under a scanning electron microscope.
Photo credit: Photo courtesy of Andrei M Sarna-Wojcicki, U.S. Geological Survey

ukinrek

Ukinrek Maars, two low-lying volcanoes on the Alskan Peninsula, spew ash thousands of feet into the air in this 1977 eruption.
Photo courtesy of Juergen Kienle

Kristi

Kristi Wallace digs for volcanic ash in Alaska.
Photo courtesy of USGS