Why does a composite volcano have a cone shape

Volcanic cones are among the simplest volcanic landforms. They are built by ejecta from a volcanic vent, piling up around the vent in the shape of a cone. One stratovolcano may have multiple summits when individual cones overlap one another. The Three Sisters volcanic complex in Oregon is an example of a complex. Alternating eruptions of volcanic ash and lava cause layers to form. Over time these layers build up. The result is a cone that has a gentler.