The skittish saga of Plymouth Rock says more about how we Americans memorialize our heritage than about the heritage itself. Most probably ignored by the pilgrims themselves, the legend of the rock was belatedly incorporated into memories of Mayflower descendants and successive efforts to move the rock to suitable, and ever grander, settings as a focus for Forefathers Day celebrations resulted in its being split in half twice and damaged by souvenir hunters. Fritz acknowledges that historians have begun to wonder whether there might be some truth to the rock's claim to fame and admits that, whatever the case, "Americans weren't going to argue about it anymore." We're inclined to agree that the whole business isn't all that earthshaking, and Handelsman's weightless illustrations add to the overall impression of insignificance. Nevertheless, we can imagine lots of children saddled with bicentennial reports and field trips welcoming the chance to cast a stone or two at the mythmakers. And at least Jean Fritz always manages to tell us something we haven't heard before. . . and with such easy informality that even a footnote like this is worth a glance.