English foursome Arc emerged from Skip Bifferty [aka Heavy Jelly] in 1970. They were a lesser but very talented blues-based heavy prog outfit comprised of Michael Gallagher's keys, Tom Duffy's bass, the drums of David Montgomery and guitarist John Turnbull. Occasionally compared to Patto though they also remind of Supertramp if that group had been young and hungry, Arc sound not unlike many bands of the era who took from what the Beatles had established but adding a harder, rawer feel mixed with the semi-classical sparks of early Yes, making 'At This' a respectable collector's item.
The untitled fourth studio album by the English rock band Led Zeppelin, commonly known as Led Zeppelin IV, was released on 8 November 1971 by Atlantic Records. Produced by guitarist Jimmy Page, it was recorded between December 1970 and March 1971 at several locations, most prominently the Victorian house Headley Grange. Led Zeppelin IV was a commercial and critical success, featuring many of the band's best-known songs, including "Black Dog", "Rock and Roll", "Going to California" and "Stairway to Heaven". The album is one of the best-selling albums of all time with more than 37 million copies sold. It is tied for third highest-certified album in the United States at 23x platinum. Writers and critics have regularly cited it on lists of the greatest albums of all time.