It doesn't matter whether C-14 is produced by a decay chain or is cosmogenic. The C-14 concentration will build up at the same rate, with the same math, as a short-lived isotope formed from a long-lived parent.
It's not quite that simple. The calculations work for a constant production rate, but the cosmogenic production of C14 is not constant.
And there are other factors, human activity has upset the balance with nuclear testing, and with the release of old carbon from burning fossil fuel.
I think that we can agree that, as a practical matter, the atmosphere is close enough to equilibrium that radiocarbon dating will produce reasonable results without correcting for the differences.
However, corrections are needed - to account for historic variations as well - if we want really accurate dates. And the argument that the Earth must be young because the atmosphere is not in equilibrium is just plain wrong.
Wikipedia states that the Redwall Limestone is found in Northern Arizona, southeast California, New Mexico, and southern Utah. The Tapeats Sandstone is found in northern Arizona (Grand Canyon), central Arizona, southeast California, southern Nevada, and southeast Utah
That map - and similar ones - seem to come from Creationist sources (and only Creationist sources), which is a bit of a red flag.. The little investigation that I have done suggests that they are probably including other formations, such as the St Peter Sandstone.
So if I understand correctly we have similar rocks deposited at the same time (with some leeway, no doubt) rather than a single formation. In some cases the similarities could be quite extensive - possibly even derived from the same source of sediment? but nevertheless there are reasons to consider them distinct.
Another point to consider, especially with older formations, is continental drift. Places which are far apart now, may not have been so when the material was originally deposited.
To make a quick reply, the idea is that the rate of deposition can vary, but it would be surprising indeed - at least to geologists - to interpret a massive formation like the Redwall as being due to a single event.
But my main point is this: it is wrong to describe the Redwall Limestone as being "all Redwall Limestone" when it is in fact a mix of varying limestones, dolomites and chert. The Redwall Limestone is composed of distinct "members", and even those are not uniform. here is a description of the actual composition - perhaps a bit technical but it does make it clear that even the individual members are not homogenous.
Hundreds of millions of years is an exaggeration, so let's not worry about that.
Limestone is especially easy to explain - because so much of it is biogenic. So long as the organisms producing it keep on going there will be sediment to deposit.
Really, the mechanisms of deposition aren't believed to be any different from those operating today. And so long as conditions remain similar, why shouldn't the material deposited also remain similar ?
The fact that it's only 540 million years to the Cambrian supports my point. No single formation is likely to occupy more than a third of that.
And I'm certainly not going to reject scientific conclusions just because you find them "strange" for some unexplained reason. I find Relativity and Quantum Mechanics to be much stranger, and I'm still happy to accept them.
What you are imagining is quite strange but it isn't the reality - the rocks are not is neat and tidy as you think. Not nearly. Now, the geological periods are based on the rocks, but not because there are sudden closely synchronised changes in the rock being deposited on a global basis. (This is even more true of subdivisions of the major periods which are NOT recognised globally). Rather, there are global changes affecting the environment which, by my understanding, have a more gradual effect.
In reality the iridium layer produced by the meteorite strike at the end of the Cretaceous was something of a gift for geologists because it did provide a precise marker for the end. Something that the rocks otherwise did not provide.
Since the periods are identified from the rocks, and since they represent the effects of global changes, and since they are not at all precise where the boundary is actually present I am at a loss to see anything actually strange.
Perhaps you could point to a genuinely strange example ? Let's have something we can clearly look at instead of arguments based on the way you think things are.
Every boundary ? Well, let's consider the Redwall again.
The Redwall is from the Carboniferous.
In places it sits on the Muav Limestone from the Cambrian. A difference of more than 100 million years, missing out the Devonian altogether. Is it really strange that rocks deposited at such different times should be different ?
In other places it sits on the Temple Butte Limestone, which is closer in age - but even there, there is a break in deposition, again for a considerable period. Again, not strange.
Above you have the Surprise Canyon formation, which is also quite similar in age, also starting in the earlier part of the Carboniferous. So this doesn't represent a boundary between geological periods, but even here there is a long break in deposition, as shown by the erosion of the Redwall surface.
In there being any correlation whatever between a rock type and a time period.
That isn't really strange. The rock has to be deposited at some time, and it isn't surprising that it would all be deposited within a single geological period since those periods are so long. So, to the extent that it is true it isn't strange at all.
In there being a pattern of time periods marked by rock types that repeats up the entire geo column.
That would be strange if it were true. But it isn't,