We're taking it waaaay back this time, dialing the clock back to the decade where hard rock and heavy metal were planting their seeds, progressive rock was finding its foothold and punk redefined what it meant for music to be truly rebellious. That's right, the 1970s! The decade can be the hardest to define when talking about hard rock and heavy metal as the lines often get blurred, namely because they didn't quite exist as separate genres yet. Now, here we are, trying to set guidelines and limitations on music that was more or less boundless in its aim at the time.

As we count down the Top 70 Hard Rock + Metal Albums of the 1970s, keep these parameters in mind: The albums that made the cut were selected for a multitude of reasons, including impact, influence, longevity, success and, of course, how great it is from start to finish! Bands like Black Sabbath, Deep Purple and Led Zeppelin were the hardest rocking acts of the era while acts like Rush and King Crimson were standouts in the prog community, as limited and nebulous as it was at the time. They may not be the hardest rocking or heaviest by today's standards — some definitely are — but the definition has changed drastically. Forget everything that's happened after 1979 and get to it!

Scroll through the gallery below to see the Top 70 Hard Rock + Metal Albums of the 1970s!