A case in point are Iron Butterfly who were active in the late 1960’s / early 1970. Iron Butterfly whose heavy dramatic music clearly bridged the gap between the psychedelic/ blues bands of the mid-sixties such as Hendrix, Cream, The Doors and The Beatles (later period) to the heavier and often darker metal and prog acts of the seventies like Zeppelin, Purple, Sabbath and Yes & ELP.... Great Great band: 5 STARS