Our Living Earth

Viewed simply as a pop-up, this has often-dramatic feats of paper engineering; one memorable picture shows the breaking and shifting of the ocean floor. But as a work of basic nonfiction, the book falters, with an abundance of abstract data, particularly numbers, some oversimplification and other problems that spring up when such a general topic is reduced to five full-page spreads. In showing all the life that existed before the advent of human beings, the author employs the oft-used example of a clock, divided into 12 hours; Homostet sapiens enters in the last quarter second. But even this is vague: ""Midnight: Softbodied creatures and jellyfish swam in the seas. 1:00 a.m.: Creatures with hard parts had evolved. This is probably the most important change in animal evolution.'' Young readers will shrug off these statements, or ask a resounding ``Why?'' before moving on to more informed sources. Ages 10-13. (October)