Time Ghost

Katz (Whalesinger) combines fantasy, science fiction and ecological issues in this appealing tale of time travel, set in the 21st century with excursions to the year 1993. Sara's activist grandmother takes her two grandchildren and their best friends out of their enclosed city to the North Pole, where she is protesting impending oil-drilling. But when Sara and her friend Dani break an antique pendant, the two girls find themselves transported back in time, with Sara inside her then-adolescent grandmother's body and Dani a ""time ghost"" outside a body. Their travels produce a solution to the conflict between Sara's grandmother and the oil-drillers. Katz, while dwelling a bit lengthily on the process enabling time-tripping, draws stimulating comparisons between the ""past"" and the girls' own era (Sara and Dani have never seen a real horse, only an image on the ""televid""; they marvel over the long-ago custom of women changing their names upon marriage). The environmentalist message comes through strongly, yet it stifles neither the characters nor the plot. Ages 9-12. (Apr.)