Phreatic refers to geologic processes and features associated with shallow
water. It is most commonly used in reference to ground water and volcanic
explosions. A phreatic explosion is a "volcanic eruption or explosion of
steam, mud, or other material that is not incandescent; it is caused by the
heating and consequent expansion of ground water due to an underlying
igneous heat source."
Fiamme are "Dark, vitric lenses in welded tuffs, averaging a few centimeters
in length, perhaps formed by the collapse of fragments of pumice."
Vitric means glassy.
Steve Mattox, University of North Dakota
Source of Information:
Bates, R.L., and Jackson, J.A., 1987, Glossary of geology: American Geological
Institute, Alexandria, VA, 788 p.
Tara-lea Weedon
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