When the 60’s turned into the 70’s there was a musical crossroads. The American blues had had it’s run with teens on both sides of the Atlantic long enough so that the blues-offspring named rock’n’roll had to expand or die. It did not die, it expanded in all kinds of directions! And right there in the crossroads between blues-based rock and all the world’s other sub-genres of rock, something happened to the blues. The format got experimented with, expanded and almost made unrecognizable.