A PBS documentary from 1983 co-produced with the BBC.
From the VHS box: "Volcanoes produce a wide variety of different features on the surface, which are often controlled by the viscosity of the magma, which is in turn controlled by its composition and the temperature at which it is erupted. This is demonstrated with a variety of volcanic features from active volcanoes in Iceland, Hawaii, Sicily, and North America. Includes unique footage of a number of important eruptions such as those of Mt. St. Helens in the U.S.A. Also examines the volcanic and sub-volcanic igneous structures."
