This is a timeline documenting the formative events in heavy metal music before 1970. Since the dawn of rock music in the 1950s and continuing through the 1960s, various artists pushed the boundaries of the genre to emphasize speed, aggression, volume, theatricality, and other elements that became staples of the heavy metal style. In the late 1960s, this experimentation coalesced into various rock subgenres like hard rock, acid rock, and psychedelic rock, which were all influential in the development of heavy metal.