The relevant question isn't geological terminology, it's what non-geologist commentators on the blues mean when they say "Mississippi Delta."

As a layman, my perception (and that's all it is) is that what Alan Lomax and others called "the Delta" was restricted to southeast Louisiana and southwest Mississippi, much as Guest suggests. In that case, if the blues began in Memphis, for example, Lomax would be in error.

Did Lomax ever define the area he called "the Delta"? (I suspect that if he'd meant the geological "Mississippi Delta," he'd have said something plainer, like "the banks of the Mississippi from the Ohio down." Did he? A "delta" is usually taken to mean the area where a river obviously diverges in a delta-like pattern close to its mouth.

There seems to be inevitable confusion between the technical "Mississippi Delta" and the easily understood "Mississippi River Delta."

I don't know Joseph Scott, but I do know an ad hominem argument when I see one. The issue is the comparative reliability of the cited sources. If you have reason to doubt his conclusions, go back to the sources and show why he's wrong.

It seems rather obvious that given the early obscurity of the blues among writers, and the inability of anyone in the 1920s to carry out extensive ethnomusicological studies across the South - or anywhere - any claims about where the blues began must have been based on limited evidence and mere impressions.

Even W. C. Handy's testimony, while extremely valuable, is inconclusive. When he heard the blues in Indiana for the first time, they might already have been common in Florida, or Oklahoma, St. Louis, or (even) Louisiana. Who knows? Nobody was looking for them.

Questions about place of origin of folk-music characteristic are generally unanswerable in any detail. The historical information is rarely sufficient.

The farther back you go before the first known mention, however, the less likely the phenomenon is to have existed. I think that saying the blues seem to have existed in parts of the South some years before the First World War, almost solely among African Americans, is about as far as one can go.

It would be interesting to know who first commented on "blue notes," however they might have been described, and when. The Oxford English dictionary's earliest example of the sense we mean is from so late as 1915, suggesting the influence of Handy's compositions. Earlier than that it simply meant "an incorrect or off-pitch note."

So it's easy to see how the secondary sense of the word developed - from a theoretically "wrong" note to a perfectly acceptable one.