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

Dr Adequate's image does appear as if it may be composed of soft material, and additionally the bending must be due to deformation. So I don't think his image is evidence for boundaries between layers forming unevenly.You've given participants the impression that your position is that layers do not form unevenly, that they only become uneven later. But what you've just said, that you want evidence of a level flat boundary, puts this interpretation into question, so perhaps it would help if you reexplained your position. By calling what looks to be a contradiction to your attention I'm trying to avoid you finding yourself in the position where you believe no one is listening to what you're saying.

I'm not replying to Faith, just clarifying. Faith's point here is that erosion cannot produce flat landscapes upon which sediments could be deposited to form the layers we find in the geological record. Briefly recapitulating the discussion, Message 213 contained images like this of straight contact boundaries: Faith later posted images like this to show how erosion makes a landscape uneven: The responses were a bit scattered (i.e., each response only included part of the explanation), but the explanation was that the very flat landscapes were produced by erosion, that if those landscapes later became buried that you'd have a very flat contact boundary with occasional stream and river channels cut into it, as is found in the geological record. Because the explanation was spread about, I'm not sure Faith understood that this is what people were trying to say.

Just to be sure you don't miss it, Edge recently commented on this in Message 447:

I want to clarify what other participants, especially Jar, have been pointing out about landscapes like the ones you showed in Message 345, like this one: You've been calling attention to eroded ditches in images like this one to call attention to how erosion makes landscapes uneven. Others have been trying to call your attention to the incredibly flat plains stretching off into the distance in the backgrounds of your images. These flat plains were caused by the flip side of erosion, namely deposition. It perhaps hasn't been expressed clearly, but when people say these plains are the result of erosion they do not mean that they were created by wind and water eroding away the surface in an incredibly even manner. What they mean is that the material on the plain is eroded material carried and deposited there from more highly elevated regions. Hills and mountains are eroded and the material is carried away by wind and water to become deposited on the plains below. Plains become flat because they are areas of deposition of eroded material from elsewhere, not because their surfaces are eroded flat.

I've been encouraging people to repeat and clarify as often as necessary.

This is what you said that Tanypteryx quoted: If I understand you correctly, you're referring to your belief that it is possible for erosion of a cliff face to affect the shape of an exposed boundary between two layers of solid rock. Participants like Tanypteryx and Edge have been saying that this makes no sense. If it actually does make sense then some clarification or explanation would be welcome.

I'm not sure you and Faith are referring to the same "stumps". I think your stumps might be where the vertical strata below the unconformity actually meet the unconformity. Faith may be referring to the parts of the gray rock near the center of this image that are not actually anywhere near the unconformity boundary, except near its top: This gray rock is the same one Hutton drew from a different angle that appears in the "Bottom Layers" part of his diagram as a thick vertical stratum a little to left of center: Here's an image that seems to come closer to replicating the angle from which the Hutton diagram was drawn: After looking at so many images of Siccar Point it's apparent that the diagram is pretty good but only approximate. Some erosion of anywhere from 2 to 10 inches of rock would have taken place over a couple centuries, but the angle of that tall section of big gray strata could not have changed.Edited by Admin, : Change author.

I want to better understand this exchange. When I read Faith's post I wasn't sure what she meant, but I decided not to pursue it. In your view is Faith saying that there should be abrasion between two adjacent layers of rock buried within a stack of strata? Or is she saying that abrasion can happen only where the boundary between two layers is exposed in a cliff face? Or is she referring to abrasion long ago when the upper layer was being being deposited upon the lower layer?

Please let the discussion be about the topic rather than assessments of the quality of others' contributions.

HBD made the same request. I was able to find this:

Reposting images into your message is extremely helpful. It makes no difference that the image has been posted a dozen times already, it is really helpful to have it right there in your message. It is even more helpful to annotate the image if you're calling attention to a specific part. When annotating, if it wouldn't be too ambiguous you might consider using circles, ovals, boxes and so forth instead of lines to identify boundaries, because at least in this particular discussion obscuring the boundary seems to raise doubts in the minds of some of what they're actually seeing.

This is the photo: This image is from a different part of Mosaic Canyon, but it provides a rough idea of the context. The sand with the embedded rocks was deposited atop the light-colored dolomite: It might be helpful to clarify this portion: It isn't clear what you're implying when you say you previously thought the dolomite and sandstone layers were separated. Why do you think it possible for rock layers to be separated (I assume you mean by air - of course rock layers can be separated by other rock layers), what do you think that implies about the angular unconformity, and what do you think the absence of a separation implies?

My attempts to elicit clarifications from you are only leaving me more confused. Okay, the images look odd to you for some reason, but is your focus on their minute details leading anywhere, because if not then it might better aid understanding if your comments addressed the larger message they convey about how angular unconformities form.

Okay, let me rephrase the question. Is your focus on the overall three-dimensional appearance of images leading anywhere, because if not then it might better aid understanding if your comments addressed the larger message they convey about how angular unconformities form. I don't think we know what your view really is. Earlier in this thread, after some discussion deriving from your opening post, you posted this in Message 131: So if your view is not represented in the opening post I think it would be helpful if you described your view of how angular unconformities form. We know you think the Great Unconformity formed as a result of tectonic forces and uplift, but there are open questions, and there are many angular unconformities around the world not in a region of uplift.Again, I'm not trying to debate the issues. I'm more just trying to identify the issues, which it seemed were getting lost in all the discussion about what was actually in the images. Questions can be raised about almost any image (e.g., "Is that a shadow or a recess?"), but I'm working at trying to keep the focus on those parts of the images relevant to the discussion.

In the view of this moderator, discussion of other angular unconformities around the world seems important to a better understanding of the processes that cause them.