A cinder cone is a conical hill of mostly cinder-sized pyroclastics. The profile of the cone is determined by the angle of repose, that is, the steepest angle at which debris remains stable and does not slide downhill. Larger cinder fragments, which fall near the summit, can form slopes exceeding 30 degrees. Finer particles are carried farther from the vent and form gentle slopes of about 10 degrees at the base of the cone. These volcanoes tend to be explosive but may also extrude some lava.
Cinder cones are numerous, occur in all sizes, and tend to rise steeply above the surrounding area.
Those occurring on the flanks of larger volcanoes are called parasitic cones. Volcanic activity typically alternates between short active periods and much longer dormant periods. An extinct volcano is one that is not erupting and is not likely to erupt in the future. A dormant volcano, while currently inactive, has erupted within historic times and is likely to do so in the future. An inactive volcano is one that has not been known to erupt within historic times.