Gr 7 Up In a clear journalistic style, Carlin chronologically details the evolution of rock and roll music and its offshoots. The origins of this musical phenomenon are traced back to a blending of black and white folk music traditions underlying 20th-Century pop music. As he follows the development of the different trends in rock music, Carlin offers a social history of the times as well as the musical one. Rock is defined as a genuinely American form, but its penetrating influence in Great Britain is shown in the discussion of groups such as the Beatles and the Rolling Stones. The book surely could be ``a starting point for further exploration'' as it is intended. The logical format offers easy access, and each chapter is followed by a bibliography and a discography. Several musical terms in the text remain undefined, which could be a drawback for readers totally unfamiliar with music. Rock music is a field which is constantly changing and of high interest. This would be an excellent addition to collections which already include Encyclopedia of Rock/Pop Stars (Gallery, 1985) and Jeremy Pascall's three-volume Story of Rock (Phoebus, dist. by Columbia House, 1976; o.p.), for example. Renee Steinberg, Fieldstone Middle School, Montvale, N.J.