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Faith  Suspended Member (Idle past 1466 days) Posts: 35298 From: Nevada, USA Joined: |
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Author | Topic: Evidence that the Great Unconformity did not Form Before the Strata above it | |||||||||||||||||||||||||||||||||||||||||||
edge Member (Idle past 1727 days) Posts: 4696 From: Colorado, USA Joined: |
What are you looking at in the gneiss that indicates it experienced deformation?
I'm pretty sure that it is both deformed and eroded. Just look at the layering in the gneiss and you will see that appears to be going in different directions. Is this gneiss "already deformed" or is it "already eroded". You've just said both. I think everyone could agree about "already eroded" because that's what we already know about the boundary between the Precambrian gneiss and the Potsdam sandstone. This would, of course, be a problem for most people professing a young earth scenario because you've got sedimentation, dynamic metamorphism (deformation), more sedimentation (the Supergroup in the GC), faulting and then more erosion even before the Great Unconformity even formed.
I'd like to bring up something that was under discussion a while back, your doubt that erosion can result in flat horizontal surfaces. I just serendipitously came across this GIF of a meandering river changing its course:
Ah, yes, this sends us full circle back to the Grand Canyon, incised meanders and formation of flat erosional surfaces...
Meandering is what happens to rivers that travel across relatively level landscapes. The changing meanders that you see in the above image level out the area. Over more years the river will change its course even more dramatically, with changing meanders that flit about (in geologic time), flattening and leveling the landscape. Flat plains are generally just way stations for sediments that are being carried from higher elevations to lakes or seas.
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edge Member (Idle past 1727 days) Posts: 4696 From: Colorado, USA Joined: |
A little content would be helpful. I have to guess: You don't think it makes sense to talk about an increase in rock volume unless there's actually more sediment added? Granted my analogies aren't that great but stretching versus compaction ought to make the point that volume can increase or decrease simply mechanically.
There are ways of doing it, but there is always evidence that it has happened. What is your evidence?
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Faith  Suspended Member (Idle past 1466 days) Posts: 35298 From: Nevada, USA Joined: |
Evidence: layers thinner in one place, thicker in another place.
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ThinAirDesigns Member (Idle past 2395 days) Posts: 564 Joined: |
No, that's just evidence of thinner in one place and thicker in another.
JB
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ThinAirDesigns Member (Idle past 2395 days) Posts: 564 Joined: |
Baseball on kitchen floor.
Faith: "Next door neighbors kids threw ball through window" Edge: "What's your evidence for that?" Faith: "Ball on kitchen floor." Faith, evidence would be something like: Broken kitchen window facing neighbors yard where kids play baseball every afternoon. The ball on the floor is just evidence for a ball on the floor.
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Admin Director Posts: 13018 From: EvC Forum Joined: Member Rating: 1.9 |
He then kept insisting it would involve volume so I said OK then the volume must have expanded that small amount, not really thinking. A couple of points. First, about the "not really thinking" part, could I strongly suggest that's inadvisable, that you should think things through before posting? You've heaped a great deal of abuse on people for not understanding you and always thinking you're wrong, so I think you owe others at least that much, to cease issuing half-baked flights of fancy. Second, the possibility that the solid rock of a lithified sedimentary layer could somehow expand in volume in any visible amount is something that few people would ever entertain for even the merest instant. If you don't want to feel like you're ideas are being treated as if they're less than stellar then you can't just say things like this off the top of your head.
The answer I'd give now to explain the difference is that the layers to the right must have thinned. Thinning? I think you must have given this answer as much thought as the one about thickening. What evidence are you looking at that suggests they "thinned"? This is a rhetorical question because obviously you're not seeing any evidence in the image, else you would have already seen that evidence of "thinning" and never made your earlier suggestion of thickening. Also, realize that more compressed layers would be denser and harder and therefore less likely to crumble and collapse, as here:
No, I probably wouldn't have said the left side sags if I had only the street view to go by. Right, exactly. The evidence, and low-res evidence at that, doesn't support the notion.
But since it looks like a sag on the other view and can still be identified somewhat on the street view, I'll still try to make the case. Well, if you must, but this moderator's advice is that you're pushing a very improbable scenario onto very slight evidence, to say the least. This is the kind of thing that frustrates other people no end. If you won't stop doing such things even while I'm calling your attention to them then there is little I can do. There's only so much a moderator can do to enforce civility in the face of such behavior. But since you're still trying to make the case, then please explain what evidence you're seeing in the image that tells you the layers on the left "sagged". Edited by Admin, : Typo.
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edge Member (Idle past 1727 days) Posts: 4696 From: Colorado, USA Joined: |
Well, rock, including sandstone, does stretch:
Hopefully to clarify, stretching does not imply a volume change. To get a volume change there are basically two ways: Lineation - Wikipedia(geology) But if that isn't the cause of the greater volume between contacts, then it must be that the narrower part to the right was formed by compaction. I'm OK with either explanation. -- add or subtract to the rock mass-- compress or expand the existing rock mass Examples of the first are expulsion of water, or intruding an outside material such as a magma. There is always evidence such processes. The second is mainly done by changing the confining pressure and would be governed by Poisson's ratio for the rock. This is probably not what we are talking about. Edited by edge, : No reason given.
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edge Member (Idle past 1727 days) Posts: 4696 From: Colorado, USA Joined: |
Baseball on kitchen floor.
This is a good analogy.Faith: "Next door neighbors kids threw ball through window" Edge: "What's your evidence for that?" Faith: "Ball on kitchen floor." Faith, evidence would be something like: Broken kitchen window facing neighbors yard where kids play baseball every afternoon. The ball on the floor is just evidence for a ball on the floor. What Faith should show us is the addition of material to the volume of rock in question. She could do this by showing that the sandstone has undergone some kind of chemical reaction to expand its volume, perhaps; or maybe some kind of flow features (after all, it's plastic, right?) into the sandstone mass. However, by her own model of 'gaps' in the lower layers, maybe there should be gaps in the upper layers also. Just smaller ones... We can actually see such things in some mining operations, but there is usually pretty good evidence that it has happened. Like mining equipment laying around...
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Admin Director Posts: 13018 From: EvC Forum Joined: Member Rating: 1.9
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Faith writes: "Deformed" refers to its being higher in one place than the other but that concerns the idea that it was pushed up into the sandstone, which I still have to give better evidence for according to you although I think I've given good evidence already. First a brief moderator comment. This is another thing that frustrates people, referring to evidence as "good evidence" when it was immediately challenged and questioned and no one accepts it but you. By this criteria, all your evidence must be "good evidence." Now, about your "good evidence". If one of the things you're referring to as "good evidence" is the appearance of disturbance in the rockface of above layers, then that was immediately and repeatedly challenged, and you have not as yet provided any explanation for how you know that rockface represents a disturbance and not just the result of blasting and excavation. If one of the other things you're referring to as "good evidence" is that the top of the gneiss at the outcrop is possibly higher there, I think everyone grants that this is possibly true (but only possibly because the image is ambiguous on this point, as on many other points), but it isn't evidence. There isn't anything about a level change in a boundary that automatically says "pushed up." And if one of the other things you're referring to as "good evidence" is that there could be a slight leveling out of the layers above the outcrop, I think everyone grants that this is possibly true (but only possibly because the image is ambiguous on this point, too), but this isn't evidence. There isn't anything about a leveling out of layers that automatically says "pushed up," and this seems improbable. And if one of the other things you're referring to as "good evidence" is that there could be a diminishment in total thickness of that set of layers with the lighter color, then I think everyone grants that this is possibly true (but only possibly because the image is again ambiguous on this point), but this isn't evidence. There isn't anything about a diminishment of thickness of a set of layers that leads to the conclusion that they could only have been "pushed up," and this seems very improbable.
HOW flat is the surface eroded by meanders? They leave raised areas at the edges of their sharp turns, don't they? Might you be raising a possibility "without thinking" again? It is indeed amazing that for almost any fact about the real world that you somehow arrive at a contrary conception. Anyway, I'm sure there are some places where local conditions have caused sharp meander bends with higher banks on the outside, but I think if you look at these images of meandering rivers that you'll see that isn't commonly the case.
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Admin Director Posts: 13018 From: EvC Forum Joined: Member Rating: 1.9 |
edge writes: I'm pretty sure that it is both deformed and eroded. Just look at the layering in the gneiss and you will see that appears to be going in different directions. Maybe I've gone off in the wrong direction, but I thought Faith was using a different definition of "deformed," or at least adding additional aspects to the existing definition. For example, in Message 1680 Faith said, "'Deformed' refers to its being higher in one place than the other but that concerns the idea that it was pushed up into the sandstone..." I assumed in my response to Faith that when she said "deformed" that she meant "deformed upward into the sandstone." Please let me know if I've misunderstood something.
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edge Member (Idle past 1727 days) Posts: 4696 From: Colorado, USA Joined: |
Please let me know if I've misunderstood something.
I see what you mean now. This discussion has gone down so many rabbit holes that I'm completely confused at times.
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edge Member (Idle past 1727 days) Posts: 4696 From: Colorado, USA Joined: |
If one of the other things you're referring to as "good evidence" is that the top of the gneiss at the outcrop is possibly higher there, I think everyone grants that this is possibly true (but only possibly because the image is ambiguous on this point, as on many other points), but it isn't evidence. There isn't anything about a level change in a boundary that automatically says "pushed up."
Exactly. I believe that there is some relief on the gneiss surface, and that is only evidence that the surface is irregular. I think Faith's logic here is that the surface is irregular due to 'intrusion' of the basement, but that the evidence for intrusion is the irregularity.
It is indeed amazing that for almost any fact about the real world that you somehow arrive at a contrary conception. Anyway, I'm sure there are some places where local conditions have caused sharp meander bends with higher banks on the outside, but I think if you look at these images of meandering rivers that you'll see that isn't commonly the case. Here is a photo of meanders and abandoned meanders in the Imuruk Basin of the Seward Peninsula. It gets pretty flat out there...
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Faith  Suspended Member (Idle past 1466 days) Posts: 35298 From: Nevada, USA Joined: |
Unless somebody comes up with a new example that looks interesting, or wants to insist that I address a particular issue, assuming I'm in a position to do that, I don't see any point in my continuing on this thread until I'm able to do the experiments with sand in a couple of months.
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edge Member (Idle past 1727 days) Posts: 4696 From: Colorado, USA Joined:
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Heh, somehow, I never found this link before:
http://www.gly.uga.edu/railsback/VFT/VFTManitou.html Faith should read the whole thing if only to show that there are crazy people outside of this Forum. Brainwashing college students... scandalous...
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Admin Director Posts: 13018 From: EvC Forum Joined: Member Rating: 1.9 |
Faith writes: I don't see any point in my continuing on this thread until I'm able to do the experiments with sand in a couple of months. Concerning horizontality, you believe that sand falling uniformly upon a submerged sloped surface would pool at the lowest point as if it were water. A little contemplation about how that could possibly happen should bring you to the same conclusion as everyone else, that such an experiment is as unnecessary as dropping a rock into water to prove it sinks. If loose sand really flowed to the lowest point then all beaches would soon be bare as the sand would flow out into the deep ocean as soon as it was stirred up by a wave. Sand can maintain a steeper angle of repose on land, but it doesn't flow to the lowest point on land either. Here's an image of a very steep street. Do you know what would happen if a dump truck dumped a load of sand in the middle of this street? It would run downhill a few feet and then sit there. Or what if you sprinkled sand very slowly on this street. The grains might rebound a few inches downhill off the hard surface, but they would otherwise just sit there.
Or think about it another way. You create a sloped surface of loose sand on the bottom of the aquarium. The sloped surface of loose sand has no trouble maintaining itself. It doesn't flow to the lowest point and form a horizontal surface. It just sits there. Now a grain of sand falls somewhere on the sloped surface and becomes just another grain of sand making up the sloped surface. Why is it any more likely to move toward the lowest point than any of the other grains of sand that were already there? And the same is true of all subsequently falling grains of sand, assuming they're falling uniformly across the sloped surface. Only if all the grains fell in one place and built up a mound would the sand tend to roll off that mound more down the slope than in any other direction. A 50-lb bag of fine playground sand is $3.69 at Home Depot, a cheap aquarium is around $20. A couple people here have made noises that they might be willing to carry out the experiment and post photos. Would you accept such evidence?
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