Now something from the dawn of Heavy Metal ...
The first six Sabbath albums are all brilliant and amazingly consistent. The self titled isn't my favourite (that's Paranoid) but it's very close and introduced the world to a whole new sound. Tony Iommi's finger chopping factory accident led to a unique style of playing that helped create the heavy throbbing riff that Sabbath became famous for and launched an entire genre of like minded bands.
Somehow I left Black Sabbath off my Top 50 Seventies albums, another mistake though partly motivated by not wanting to have too many albums by one band in the list.