How Volcanoes Work

 Image Described in Caption
 Linear vent system on the volcanic field Harrat Khaybar in western Saudi Arabia. The basaltic vent system is Neolithic in age, feeding flows that advanced downslope, largely to the left (east) of the vent system. It is composed of aligned spatter cones and spatter ramparts and contains a large scoria cone at its northern terminous. Such vent systems are typical of fissure eruptions. Photo by Vic Camp.