1911 Encyclopædia Britannica/Mofetta

MOFETTA (Ital. from Lat. mephitis, a pestilential exhalation), 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 word is used frequently in the plural as mofette, or, following the French, mofettes. The volcanic vents yielding the emanations are themselves called mofette. They are not uncommon in Auvergne and in the Eifel, notably on the shore of the Laacher See; whilst other examples are furnished by the Grotta del Cane, near Puzzuoli, the Valley of Death in Java, and the Death Gulch in the Yellowstone Park.