Two heavy rock masterpieces were thrust upon the public in the first year of the seventies, Deep Purple's "Black Night" and the Birmigham outfit "Black Sabbath" with 'Paranoid', it was fitting that both bands came from the industrial heartland of Britain as their musical style was as hard and heavy as the steel mills of Sheffield and Birmingham . . . . Sabbath in particular, was the definition of 'heavy', it was a grinding freight train of rock and roll overload that almost buried Purple and Zeppelin in its wake and certainly had the squares and the straights well and truly fucked up and fully freaked out.
The band's name alone was causing the clergy and the chinless elite to pull their hair out and the whole nature of the music was so far removed from even the Stones, Cream, Vanilla Fudge and Zeppelin that the majority of the music press of the day, unlike the instant fan base the band attracted, were quite scathing in their reviews of the first two Sabbath albums . . . . on a technical level, let's be honest here, Sabbath were not the virtuosos that Page and company were, or even Deep Purple, that their primary contribution to rock + roll was the bar chord is evidence enough of their approach . . . . but, if it ain't broke . . . .
Personally, I don't find find them any heavier than my all time fave hard/heavy rock act, the manic, in your fucking face, Motor City 5, but they sure as hell were nothing like any other band of the time or since, and shit, were they loud . . . . you'll note I haven't introduced the term "Heavy Metal", as originally coined by the writer William S Burroughs, as I don't believe it was first used to describe Black Sabbath, or Deep Purple for that matter, in a musical sense . . . . some critic had already used it in reference to Hendrix and it was also written in an article regarding a description of MC5 and their sound, therefore fans, Heavy Rock is the most I'm prepared to concede.