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Part of Hall of Planet Earth.
AMNH/R.Mickens
Glass Mountain began with an explosive eruption of ash that blanketed the surrounding forest, killing all the trees. Hot gases from a second eruption melted the ash and burned the trees, remnants of which are preserved as charcoal. Radiocarbon dating of the charcoal indicates that the date of eruption is approximately A.D. 1113
Provided by Echo Mountain Quarry, California