I forgot to mention that rock'n'roll's other roots were country. Maybe "Rock Around The Clock" (which I still think is a great fun song) was the first big commercial hit that is now classified as rock'n'roll but Bill Haley didn't just wake up one morning playing the guitar and singing that way. I'm glad to hear about the Hank Williams song, I'll have to check it out sometime. But I prefer the term "folk process" to "rip-off." The physical process is the same but the intentions are a world apart.

Another rock and roll root is quartet singing from the African-American community in the '20s and '30s (or earlier?) I heard a song on the radio from that era that is virtually indistinguishable in style from the "do-wop" sound of the next generation, which was so important in the development of rock'n'roll. The same could be said about white bluegrass/gospel quartet singing, compared to say, surfer music.

I remain, Your humble and opinionated servant, Jon W.