Cinder cone volcanoes are made of material called scoria, a low density form of basalt. Scoria forms as gases in the lava try to force their way out of the molten material through a vertical path.
As the gas escapes, it carries lava high in the air. This ash material then cools into rock filled with air pockets before it strikes the ground forming a cone around the vent without sticking together. Lava rock from cinder cone volcanoes is popular in landscaping. The red rock is a lightweight material that is easy for the landscaper to transport and spread. In the United States, cinder cone volcanoes are visible in California, Oregon and Hawaii.