@bdp24 - I make the same distinction you do, between rock and roll and 'rock'- the former, to me, is the stuff from the '50s and after, Elvis, Jerry Lee Lewis, Chuck Berry and all that it inspired- mixing R&B, gospel, country, etc. JLL Live in Hamburg is one of the great recorded performances, though not the best sounding recording.
To me, in my fractured view of music history, rock (as opposed to rock and roll) grew out of the psych period and went in several directions-- from the very heavy stuff which is now considered proto metal (the genres labels can be constricting, i like some of the early stuff from Sabbath, Zep, Purple in the post-1970 era), hard rock (many of those UK bands, like Free, started as blues rock bands and morphed into a more radio friendly style), and stuff that is now labelled 'classic' rock.
To me, in my fractured view of music history, rock (as opposed to rock and roll) grew out of the psych period and went in several directions-- from the very heavy stuff which is now considered proto metal (the genres labels can be constricting, i like some of the early stuff from Sabbath, Zep, Purple in the post-1970 era), hard rock (many of those UK bands, like Free, started as blues rock bands and morphed into a more radio friendly style), and stuff that is now labelled 'classic' rock.