Well, I would tend to think that, at best, AUs make a case that at least two events occurred: one for the layers at the one angle and one for the layers at the other. I fail to see how AUs indicate that all the layers involved are sequential and that every lower layer must be entirely solid before another layer can be deposited on it.
Or have I misunderstood you?
well, it requires a bit of inductive logic. extrapolate it another step.
if we have an angular section, under a flat section, every layer below the flat section had to have been formed before. so they had to be solid, then upturned, then a new layer formed on top.
so if we have more than one of these, and we do, and they happen in different layers, and they do... what does it mean? say we have layers a, b, and c. now, in on place, we have an uncomformity between a and b. so b had to be later than a. now suppose we have another unconformity elsewhere between b and c. so not only does c had to have been formed after b, but after a as well by the commutative proprety.
considering the vast amount of angular unconformities we have occuring at so very many different locations in the geologic column, it stands to reason that the layers were laid down sequentially.
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