From The Art and Popular Culture Encyclopedia
Early years (1960s)
As stated, one of the major influences of hard rock is blues music, especially British blues. British rock bands, such as Cream, The Rolling Stones, The Beatles, The Yardbirds, The Who and The Kinks modified rock and roll, adding to the standard genre harder sounds, heavier guitar riffs, bombastic drumming and louder vocals. This sound created the basis for hard rock. Early forms of hard rock can be heard in the songs "Happenings Ten Years Time Ago" by The Yardbirds, "Revolution" and "Helter Skelter" by The Beatles, "I Can See for Miles" by The Who, and "You Really Got Me" by The Kinks.
At the same time, Jimi Hendrix, produced a form of blues-influenced psychedelic rock, which combined elements of jazz, blues and rock and roll, creating a unique genre. He was one of the first guitarists to experiment with new guitar effects like phasing, feedback and distortion, along with Dave Davies of the Kinks, Pete Townshend of The Who, Eric Clapton of Cream, and Jeff Beck of the Yardbirds.
Hard rock emerged with British groups of the late-1960s, such as Black Sabbath and Led Zeppelin, who mixed the music of early British rock bands with a more hard-edged form of blues rock and acid rock. Deep Purple helped pioneer the hard rock genre with the albums Shades of Deep Purple (1968), The Book of Taliesyn (1968), and Deep Purple (1969), but they made their big break with their fourth album, Deep Purple in Rock (1970). Led Zeppelin's eponymous first album, Led Zeppelin I (1969), Uriah Heep's Very 'eavy... Very 'umble (1970), and The Who's Live at Leeds (1970), are examples of music from the beginning of the hard rock genre. The blues origins of the albums are clear, and a few songs by well-known blues artists are adapted or covered within them.