Curious how volcanologists collect samples of ash? Last week, Alaska Volcano Observatory's Kristi Wallace teamed up with California Volcano Observatory’s Seth Burgess to sample tephra around Fairbanks. Where tephra occurs as thin layers sandwiched between other materials, volcanologists dig into the layers above to expose & remove portions of the ash bed. The ash is then studied in the laboratory & can reveal the age & source volcano of the tephra. #TephraTuesday USGS Volcanoes | Alaska Volcano