A tuff ring is a low, wide volcanic crater formed by the explosive interaction of magma with water, producing a ring of tuff (consolidated volcanic ash) around the vent. Tuff rings are significant in volcanology for understanding phreatomagmatic eruptions and the formation of volcanic landforms.
Source Lorenz, V. (1986). “On the Growth of Maars and Diatremes and Its Relevance to the Formation of Tuff Rings.” Bulletin of Volcanology, 48(5), 265-274.