CAVES AND CAVERNS

Again, by presenting the types of caves and how they are formed, Gibbons provides simple, straightforward science in picture-book format. Though sea, ice, and lava caves are mentioned, the focus here is on limestone caves. Several drawings show how rainwater containing carbonic acid erodes the limestone to form caverns filled with convoluted and beautiful spires, shards, and other shapes; one illustration defines the technical terms for these creations. The text is clear, but the drawings can be confusing—as when dripping water seems to create stalactites and stalagmites even in a cave filled with seawater. Cavils aside, a useful introduction. (Nonfiction. 7+)