WHAT MAKES THE GRAND CANYON GRAND?

Christian and Felix (Can It Really Rain Frogs?, 1997, etc.) take readers on a globe-spanning tour of the natural world, pointing out its wonders topically with chapters on canyons, great rivers and waterfalls, glaciers and icebergs, caves, mountains, and forests. Plenty of boxed side comments, plus titles, boldface terms, and random words in a variety of type styles are nicely designed to catch a browser's eye; recurring gnomic representations of Christian mingle with a plethora of casually drawn views and diagrams. The authors have a gift for choosing memorable facts and anecdotes, but are guilty of oversimplification (e.g., ``The air in high levels of the atmosphere contains less oxygen''); several of the low-tech demonstrations are recipes for domestic disaster; since the rest of the book is about water and landforms, the chapter on forests is tangential. Written with enthusiasm, the book is too slapdash to be more than superficially useful. (index, not seen, maps, diagrams, glossary) (Nonfiction. 9-11)