The creator of this Infographic contacted me with the question: did we get it right?
Well, not sure if anybody could adequately fact check this winding visual amalgam of genres related to Rock and Roll over a 100 year timeline, but it is sure fun to click around in. Click through and the first thing you'll experience is the dramatic 30 second "waterfall" progression from a handful of traditional folk musics into the labyrinthe of genres, sub-genres and sub-sub-genres that could be legitimately be classified as Rock starting in the mid-50's. They're neatly divided up in color coded families that get highlighted as you explore. Click on any of the boxes for an audio example of what what these genres sound like sourced from the iTunes store. Pretty cool.
So did they get it right? You be the judge.