The geologist author of Earth in Motion (1978) describes some major volcanic eruptions (the book starts with Mount Saint Helens, 1980), explains how these result from magma rising through ""escape vents,"" distinguishes among the forms it takes at the surface, and--illustrating with accounts of specific eruptions--tells how volcanoes are classified according to degree of violence. In the process he probes deeper into the forces at work, finally describing two new volcanoes born before human eyes and then showing how the theory of plate tectonics accounts for such events. There's a final short chapter on how people have tried to control lava flow or use volcanic conditions for energy. Fodor's prose has a leaden quality, but he has taken care to make the sentences simple and straightforward, and to organize the material for gradual understanding and easy access. With relevant photos and diagrams and the reassuring Morrow format, it could serve.