Tuff Cone

A tuff cone is a small, monogenetic volcanic cone produced by phreatic, or hydrovolcanic, explosions that occur when magma rising through a conduit reaches the surface and interacts explosively with water. Like other volcanic cones, it is built from ejecta piling up around the vent in a cone shape with a central crater, but its defining material is consolidated ash, or tuff, rather than the welded spatter of a spatter cone or the loose cinders of a cinder cone.