Evidence that the Great Unconformity did not Form Before the Strata above it

Fair enough.

That's a great find, very similar to the other road cut situation, and the arguments are the same ones we've been pursuing. I didn't even know my own argument already existed.So they dismiss the idea of a fault on the unconformity line. That pretty much leaves trying to find out if layers like those and the ones in the other road cut really will form by deposition on the slope.Just wondering: Would you say the layered rocks in the picture are highly compacted?

Geologists are actually pretty good at thinking up alternatives. The point is that they search for evidence to support different schemes. Based on the evidence, yes. Well, you have just seen a demonstration that they can. Considering that it's very lithified, yes, I'd say it was compacted. Your point being?

Not in the case of the Tapeats which we see pinching out over short distances as shown by McKee. And yet, they happen. Suggestions to you are not evidence.

Are you talking about variations in thickness from DEPOSITION or from deformation after deposition? Forces, pressures, compaction after deposition can thin out a layer for instance.Edited by Faith, : No reason given.Edited by Faith, : No reason given.

Considering that you expected there would be no drape effect, yes, there is 'somewhat more'. I'm not sure that your eyesight isn't deceiving you. When I look at McKee's drawings, I see layers thinning to the point where they completely pinch out in some cases. Something hitting you is not evidence, although we have tried that. Again, I'm not sure what you are looking at, but I see assymetric deposition of layers in the demonstration akin to the ones in McKee's diagrams. Again, I'm thinking you are looking at a different video. Some of the layers on the basement high are quite thin compared to the depressions. I'm not sure what you mean by being of equal thickness if they 'start thin at the top...'.And what do you mean by draping 'into the depressions with equal thickness'? Equal to what? I think he is referring to your tendency to dismiss evidence and conclusions without explanations other than 'it kinda, sorta looks that way'.

Seeing as there is no evidence of forced folding, it would be at deposition.ABE: (interpretation) The geometry is from deposition./ABE Most compaction is gravity related and not forced folding.And yes, this is what I've been saying all along. Compaction is a process which can produce drapes. But it is not tectonic.ABE: (interpretation) Yes, this is what I've been saying all along, but compaction is not tectonic in this case. Edited by edge, : No reason given.

You've lost me every time you've said this about compaction and "forced folding." Sometimes I'll look up your terms but sometimes they are so unrelated to what's on my mind at the moment I just let them go. Anyway, if you want me to understand what you are saying here you need to translate.

In that case please put your views about the impossibility of non-horizontal deposition on the back burner until such time as you can provide rationale and/or evidence. Just so it doesn't catch you by surprise later on let me say that this means you can't argue for your view that there's a change in the angle of tilt in the layers of the road cut that could only have been caused by sagging of the layers to the left.

Hi Faith,In responding to your post I'm going to make a moderator ruling. I think what HBD is saying is that you're dismissing evidence and arguments out of hand while providing specious counter arguments ("it looks like...", "it just comes off as..."), and that if you're going to continue in this way then there's little point in putting effort into providing even more evidence and arguments to you. HBD provided this image: It has asymmetry reflecting flow. Contrary to your claims of even distribution (paraphrasing, just thin coats with pooling in the depressions), the bottommost layer (it's yellow) does become slightly thinner as it rises up the slope, and on the far side it disappears altogether for a while. The next layer up (it's brown) looks precisely like some layers in the McKee diagram. And the next layer above that (a lighter brown) almost completely pinches out on the far side of the mound.Ideally both sides in a discussion would bow to the evidence and move on, but as that isn't happening here I'm therefore ruling that unless you can present a rationale for your position that has far more substance and far better correspondence to the evidence than "it just comes off as thinly coating the slopes on the way down to pooling in the depressions" that the geological position that the boundary between the Tapeats and Archean is an erosion unconformity, not an intrusion, has succeeded and that discussion should move on.

This doesn't appear to have any correspondence to the video at all. It's like you're looking at something completely different than everyone else, or as if you are unable to see obvious similarities in images. In his reply Edge commented similarly.If you want to pursue the point then you're welcome to argue it again, but some points need significant modification if they're to make sense to anyone. To point out just one example, you say "There is no filling of the low places in the [McKee] drawing," yet everyone else sees the layers thickening the deeper they are in the basins. If you're looking for identicalness between the sedimentation experiment and the McKee drawings then you're not going to find it and should by no means expect it. The experiment was to illustrate general principles of sedimentation, not to replicate what happened in specific regions of the Tapeats boundary with the Great Unconformity. To continue arguing your point you need to make observations that don't cause people to wonder if you're looking at the same images they are, and you need to provide a reasonable rationale for why the sedimentation experiment and the McKee Tapeats diagrams aren't uncannily similar.

Just out of curiosity, I was looking at some inclined bedding references and ran across this article on the Lawrence Formation in Kansas. Here is one of the explanatory diagrams. The caption says: Note that the horizontal, flat channel fill sedimentary strata are 'common in subaerial channels'.So, even though the layers occur as Faith would like them to be, it still implies an unconformity occurring somewhere above sea level.I rather like the inference of 'tidal regimes' for the assymetric fill because it suggests a shoreline along the Tapeats sea as it rose across the Great Unconformity land surface.For those interested, here is a schematic strat column for the study area. Note that the age of these rocks is Pennsylvanian, which would be at a time between the Redwall Limestone and the Hermit Shale in the Grand Canyon. That would be at the time when Faith says there was no erosion or tectonism going on in the Grand Canyon and, ostensibly, no where else in the world.(Ooops, I forgot, we have to ignore what's going on outside of the Grand Canyon). This is one of the common ways that some detail is added to the normal stratigraphic column by showing erosional channels cut into lower formations. As you can see, it is quite complex. Edited by edge, : No reason given.

Another video for Faith. At about 2 minutes there is a discussion on the irregular unconformity surface at the base of the Tapeats and how it formed.https://www.youtube.com/watch?v=ZoaAh0I7rJM

Earlier in the thread someone asked if drag folds could form without faulting. The answer is 'not really', because 'drag' implies friction between two bodies.However, it is possible that folding may precede faulting and consequent drag folding.Here is a diagram depicting the stages in development of a 'monocline' (a fold with only one limb). In this case the fold 'drapes' over the basement fault but shows drag after the fault has developed. One can see that if faulting continued in this diagram, the fault would propagate upward through the remaining sedimentary rock layers.Note that this 'draping' is different from soft sediment drapes, but the driving force is still gravity. There is no compression such as what we see in normal fold development.Here is an image of an actual monocline in the northern part of the Uncompahgre Uplift in Colorado. Often times the hinge zones of these folds are highly fractured (and consequently more eroded) suggesting they were hard rocks when deformed or the strain rates were rapid. Here is an example: Edited by edge, : No reason given.

Today I had the opportunity to visit the area near the St. Lawrence River where the roadside unconformity (discussed earlier) is located. Here's a link to the pictures Microsoft OneDrive - Access files anywhere. Create docs with free Office Online.
They may or may not be useful, but it was nice just to touch and see them firsthand.ABE:just to clarify1-4 Head-on walking L-R
5-7 are angled from the Right, with 7 a little closer view
8 is angled from the L
9 is pretty, unweathered sandstone
10-15 are closer shots
16 is the opposite side of the roadEdited by snapdragon, : provide context