Over thousands of years, however, these cones can reach massive size. Hawaii is the largest lava structure in the world, while Mauna Loa, if measured from the sea floor, is the world's largest mountain in terms of both height and volume. Stratovolcanoes are the most common volcanic form. They are composed of alternating layers of lava and pyroclastic material. When a quiet lava flow ends, it creates a seal of solidified lava within the conduit of the volcano.
Pressure gradually builds up below, setting the stage for a violent blast of pyroclastic material.
These alternating cycles repeat themselves, giving stratovolcanoes a violent reputation. 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.