A
cinder cone or
scoria cone is a steep
conical hill of loose
pyroclastic fragments, such as either volcanic clinkers, cinders, volcanic ash, or
scoria that has been built around a
volcanic vent. They consist of loose pyroclastic debris formed by explosive eruptions or lava fountains from a single, typically cylindrical, vent. As the gas-charged lava is blown violently into the air, it breaks into small fragments that solidify and fall as either cinders, clinkers, or scoria around the vent to form a cone that often is beautifully symmetrical; with slopes between 30-40°; and a nearly circular ground plan. Most cinder cones have a bowl-shaped
crater at the summit.