Ash and Tuff Cones
See also: Phreatomagmatic eruptionAn ash cone is composed of particles of silt to sand size. Explosive eruptions from a vent where the magma is interacting with groundwater or the sea (as in an eruption off the coast) produce steam and are called phreatic. The interaction between the magma, expanding steam, and volcanic gases results in the ejection of mostly small particles called ash. Fallen ash has the consistency of flour. The unconsolidated ash forms an ash cone which becomes a tuff cone or tuff ring once the ash consolidates (see also tuff). Flat-floored craters that scientists interpret have formed above diatremes as a result of a violent expansion of magmatic gas or steam; deep erosion of a maar presumably would expose a diatreme.
An example of a tuff cone is Diamond Head at Waikīkī in Hawaiʻi.
Read more about this topic: Volcanic Cone
Famous quotes containing the words ash and, ash and/or cones:
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—Martha Shelley, U.S. author and social activist. As quoted in Making History, part 3, by Eric Marcus (1992)