I Believe In An Age Of Bronze

I got an e-mail about this attempt to define the parameters of a Bronze Age of American mainstream comics, but I figure out why. It seems to me that if you insist on breaking comics down into periods like that and assigning minerals to them a third era is well-defined, obviously so, by the first non-Jack Kirby issue of Fantastic Four on one end and the first issues of the mega-crossovers Secret Wars and Crisis On Infinite Earths on the other. I can't even imagine any strong contenders to those candidates, at least not any that frame that general comic book era in as compelling and convincing a way, although I suppose you could quibble over, say, last Kirby/first non-Kirby. You could also go specific, and generate one of those crazy articles that you see out there in magazines to which I've never been lucky to subscribe where grown-up people spend tons of time and energy trying and name "the last Potassium Age comic per series" or whatever, but why would you want to? It's such a rough measure, and the general high and low points in mainstream comics are pretty clear -- there really aren't as many as fans of those kinds of comics sometimes think.