Hi Petrophysics1,
You seem to be addressing yourself to the larger discussion in this thread rather than to my rather minor point, namely that when you said, "Formations and their boundaries ARE NOT time lines. In special instances they could be, but in general they are not," that it was overstated. Nothing you've said here changes my mind, because nothing you've said here addresses what I said.
petrophysics1 writes:
Ash falls, or all the diatoms dying the in winter and settling out are very close to a time line,but almost everything else you look at is either prograding/regressing or transgressing.
But, as I asked already (see where I concluded with, "Not millions, surely."), how much vertically compared to how much horizontally? For example, the vertical thickness of the layers in the Grand Canyon represent ten, twenty, sometimes more, millions of years. Only at most a few hundred feet thick, the horizontal extent of these layers is for miles and miles and miles. Obviously the horizontal transgressing is far, far faster than the vertical deposition rate, and so these layers, especially at the precision of millions of years, represent pretty clear time lines.
This doesn't have anything to do with the Gilbert Delta or RAZD or some poor schmuck from Australia. I was just making a minor point that when you say that layers could only be considered time lines under special circumstances that in my opinion you were overstating the case.
--Percy