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Mofetta is a name applied to a volcanic discharge consisting chiefly of carbon dioxide, often associated with other vapours, representing the final phase of volcanic activity. The Oxford Dictionary of English lists mofetta as an archaic term for the modern word fumarole.
The volcanic vents yielding the emanations are themselves called mofette. Examples are furnished by the Grotta del Cane, near Pozzuoli, the Valley of Death in Java, the Death Gulch in the Yellowstone Park and the series of mofette in Romania‘s Harghita and Covasna counties.