These are relatively small volcanoes made of basaltic fragments. The most common types of volcanoes on earth, they are made up of cinders (nut-sized pieces of red or black lava containing bubble like cavities known as vesicles) and form steep-sided mounds with a little crater at the top. They are usually found in clusters, sometimes in groups of a hundred or more. They can also occur on the slopes of other volcanoes.
