At Siccar Point it's all exposed and the layers break off, they aren't continuous. At the GC I figure the rubble is somewhere under the strata outside the frame of the usual diagram. The strata of which the Great Unconformity was made must continue to exist somewhere too.
That's just assumptions without explanations.
No, the upper material WAS eroded but it maintained its finegrained character so that all you see is that material with the chunks of the lower material embedded in it.
Please produce evidence that th is the case. It certainly doesn't make any sense in the case of the boulder.
And in both cases, the GC and Siccar Point, the chunks are suspended above the contact line, which is NOT what you'd expect if they preexisted the deposition of the upper strata. And I can't even picture how that would happen if they were supposedly redeposited as you claim either. They'd already be there on the usual scenario, how do they get redeposited?
By my understanding that IS the case at Siccar Point. And you seem to have forgotten that the situation at the Grand Canyon is rather less simple than you suppose. There are portions of the "lower" strata still sticking up into the "higher" strata. Have fun explaining how that is possible in your scenario.
Try Lyell's experiment with folded cloth, using folded flannel, terrycloth, cotton sheet, satin, velvet. Flannel will not slide relative to flannel but buckle together, and probably not relative to terrycloth either, though it's possible the terrycloth would buckle beneath the flannel, if I had some flannel I'd check, but flannel will slide relative to satin for sure, and you'd have to test the others but there should be similar effects between the
Which combinations produce the result you claim, why, and how do you know that this applies to rock?
The lower strata were presumably built up slowly over millions of years, tilted and eroded and submerged while the upper strata were deposited, if I'm remembering the sequence Hutton had in mind correctly. That means the lower were supposedly exposed a long long time before being submerged and if the weather was the same all that time there should be a difference in the effect from one layer to another.
You seem to have forgotten to work out how long the upper strata were exposed. It' sided that you seem to think that you can do a comparison by only looking at one side. And as I remember the pictures showed a vertical cross-section, much of which may well not have been exposed in the period of erosion between the formations.
I see no differences among the vertical strata myself. And the vertical strata appear to be weathered in the same degree as the upper as well, and in that case since they were already supposedly severely weathered befpre being submerged they should continue to be far more weathered looking than the upper strata no matter how long they were exposed.
My evaluation is different, and as I have already pointed out this makes the mistake of assuming that there is no period when the upper strata were exposed to weathering while the lower were not. You need evidence, not assumptions. Hard facts, not subjective evaluations of photographs.