Sound basic geology following the same textual and pictorial pattern as Zim's other familiar What's Inside? books. A page of simple, easy to read text, and a facing picture pose the question and part of the answer while the next two pages- an amplifying text in double columns and another picture, tell about the inside. In this way the aspects of our globe- its layers, a typical coal mine, a cave, an earthquake, a volcano, a mountain-are explained. Valuable classroom material. Raymond Perlman's natural drawings in brown and green convey an added earthiness.