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Faith  Suspended Member (Idle past 1475 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 | |||||||||||||||||||||||||||||||
Faith  Suspended Member (Idle past 1475 days) Posts: 35298 From: Nevada, USA Joined: |
The "mainstream view" is that the sediment originally deposited on the pre-existing slope, and the same above that, on the slight tilt, right? ' Well, there seem to be several viewpoints around here, but any one of them is better than yours for the reasons I have given. You're going to have to give it all again if you want me to know what you're talking about. I've only seen one viewpoint against mine, and that's the idea the layers deposited in the sloped and tilted position rather than deforming later.
I don't think that "better" explains it at all, I don't even believe it.
Well, that is part of the problem. You have a belief system, we have evidence, basic principles, experience and logic. And, perhaps, better eyesight. "Belief" was being used in the perfectly ordinary everyday sense of believing something true. I could make a snarky remark but I'm the only one who ever gets "moderated" for those, you never do.
But evidence will have to wait until I can do the experiments. And by the way, nobody on your side has produced evidence for your view, either, since diagrams aren't evidence
If you are saying that sediments cannot be deposited on a slope, you are wrong. No I am not saying that, I'm saying you'll never get a normal even layer that way, such as those seen here and especially in long sequences such as are visible from a distance in the Grand Canyon. That is NOT how sloping layers are formed, they are laid down horizontally and then deformed.
It can and does happen, and it is very common. You have been given demonstrations and examples. And I'm not even saying that's what happened. I'm just saying that there is no evidence that the features we see are not related to sedimentation. And again you haven't proved it. Edited by Adminnemooseus, : Fixed 1 quote box. It was the second one down, one of the quote box in quote box. Hope I got it right.
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Faith  Suspended Member (Idle past 1475 days) Posts: 35298 From: Nevada, USA Joined: |
What I think I said was that they must have stretched that small distance, the rock being soft.
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Faith  Suspended Member (Idle past 1475 days) Posts: 35298 From: Nevada, USA Joined: |
Rock can stretch and rock can compress or compact, when still soft enough.
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Faith  Suspended Member (Idle past 1475 days) Posts: 35298 From: Nevada, USA Joined: |
It wouldn't have increased its volume, if you're talking about quantity of sediment. But stretching WOULD increase its volume in the sense of absolute measurements, the way beating egg whites or adding yeast to bread dough increases volume.
Edited by Faith, : No reason given. Edited by Faith, : No reason given.
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Faith  Suspended Member (Idle past 1475 days) Posts: 35298 From: Nevada, USA Joined: |
I'm just trying to clarify again. This is the Google Street View image of the road cut, this time without the yellow circle. I'm posting this to emphasize the point that the layers appear to tilt upward to the right across the entire image, Yes, it does give quite a different appearance.
that there's not really much if any bend at the point that you've been indicating. Which I believe I noted in my previous post.
Please let me know if you need me to add some marks so you can get your bearings in the image relative to the other image of the road cut, but what this means is that it would be incorrect to argue that there is a tilting or sagging that occurs only on the left side of the image. The layers appear to have the same general tilted upward orientation from left to right across the entire image. If you actually go to Google Street View and follow the road cut a little further to where it ends you'll see that the upward tilt to the right continues all the way. Yes, there is certainly a general tilt to the whole formation that is not at all apparent on the other view. However, there is still a particular sagging on the left as the sandstone climbs up onto the gneiss, much less pronounced than it is in the other image, but not just part of the general tilt. A definite curve or bend. The appearance of tilt on the left in the layer or two above the "sag" can't be seen from this perspective but it couldn't disappear altogether, must be merely even less pronounced than it appears in the other view. So it still remains true that there is a separate but very slight tilt on the left that isn't just part of the overall tilt. Here's the left side of the street view with the layer marked to show that there is still a recognizable sag though much less steep. Wiggly line isn't intentional.
Others can correct me if I have this wrong, but I don't believe the mainstream view is that the sediment was originally deposited on a pre-existing slope. All that's being said is that there's nothing in the image to indicate that the sediment was originally deposited horizontally. It certainly could have been horizontal, but it also could have been in some other orientation. Original horizontality is a principle more than something that should need to be proved, but I do nevertheless intend to try to construct some experiments to address all the different claims. But not to lose the point of the distinction: if the layers deposited horizontally and then deformed, that suggests that the deformation was caused by the deformation of the gneiss over which they now lie and to which they appear to be conformed in basic shape. This would be evidence that they were already in place when that deformation occurred, which is the whole point of my argument that there was no appreciable time gap between the two rocks. If, however, they were deposited on top of the already-deformed gneiss, conforming to its contours as seen, that would support the idea of pre-existing gneiss already eroded long before the deposition of the sandstone. I do feel it is necessary to repeat this because otherwise the whole reason for the dispute could get lost. Sorry if it is in the category of what you said I can't repeat. This is not meant as an argument, merely a statement of what the argument is about because otherwise it can all get lost and confused.
And as Moose stated earlier, the layers have the appearance of dipping downward away from the rock face, so the tilt isn't exclusively left-to-right. I assume this refers to the vertical tilt or incline from top to bottom? Not sure what the significance of this is.
So just to clarify once more, no one's saying the layers could not have been deposited horizontally. They're saying that there's no evidence that horizontal is the only possible original orientation. Noted. Edited by Faith, : No reason given.
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Faith  Suspended Member (Idle past 1475 days) Posts: 35298 From: Nevada, 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.
Edited by Faith, : No reason given.
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Faith  Suspended Member (Idle past 1475 days) Posts: 35298 From: Nevada, USA Joined: |
Well, rock, including sandstone, does stretch:
http://en.wikipedia.org/wiki/Lineation_(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. Edited by Admin, : Fix link.
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Faith  Suspended Member (Idle past 1475 days) Posts: 35298 From: Nevada, USA Joined: |
I agree. You are right.
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Faith  Suspended Member (Idle past 1475 days) Posts: 35298 From: Nevada, USA Joined: |
I didn't say the sagged layers became thicker as they sagged although I can see how someone could have read it that way. I was talking about the layers ABOVE the sagged area, where the contacts are so tight and yet tilt slightly from the horizontal lines to the right -- those aren't horizontal, we can see now from the street view, but there is nevertheless a slight tilt down from those in the contacts on the left just above the sagged area.
I was asked how the space between the contacts could be larger,or that's how I heard it, and I just tossed off the thought that since the rocks were still soft they must have stretched in that area. He then kept insisting it would involve volume so I said OK then the volume must have expanded that small amount, not really thinking. Eventually I took that back. But it was never about anything other than the couple of layers above the sagged area, to explain how there could be such tight contacts there if the layers are wider than those to the right. The answer I'd give now to explain the difference is that the layers to the right must have thinned. No, I probably wouldn't have said the left side sags if I had only the street view to go by. I might still have argued for original horizontality though. 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. Edited by Faith, : No reason given.
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Faith  Suspended Member (Idle past 1475 days) Posts: 35298 From: Nevada, USA Joined: |
Yeah, I noted that possibility back in Message 1481, Edge seemed to agree, and I reminded Faith of this in Message 1565. The odd thing is I never even noticed that jog until you "reminded" me of it. Then I said there couldn't be any jog there at all. Who drew that line originally? I missed it at the time.
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Faith  Suspended Member (Idle past 1475 days) Posts: 35298 From: Nevada, USA Joined: |
I spoke too soon, that's all. Please see my explanation to Percy in 1675.
Edited by Faith, : No reason given.
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Faith  Suspended Member (Idle past 1475 days) Posts: 35298 From: Nevada, USA Joined: |
With your "compaction" explanation, are you saying that rather than the orange lines having sagged down from the yellow level (which would require the magical expanding rock bs), you are saying that your short yellow lines were pushed UP from the orange level to where they are now, and the material within the pink circles was compacted that extra distance? Something like that, yes. There has to be an explanation for the difference in width, either expansion or compaction, and compaction appears to be the best explanation. But I never said the straight tight contacts indicated by the orange lines "sagged," that word I only applied to the layers below. I used the term "slight tilt" for those above. Edited by Faith, : No reason given.
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Faith  Suspended Member (Idle past 1475 days) Posts: 35298 From: Nevada, USA Joined: |
When I drew the line to indicate the sag I was looking at a much bigger closeup picture where the curve is more apparent. I don't know why only one layer seemed to show up whereas at the greater distance I identified two.
yes of course it makes a difference to see a different perspective. if snapdragon gets some good shots maybe it will make enough of a difference to give up the whole argument. I used "eroded" for the gneiss as the statement of the conventionalview that I'm arguing against. "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. HOW flat is the surface eroded by meanders? They leave raised areas at the edges of their sharp turns, don't they? Edited by Faith, : No reason given.
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Faith  Suspended Member (Idle past 1475 days) Posts: 35298 From: Nevada, USA Joined: |
Evidence: layers thinner in one place, thicker in another place.
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Faith  Suspended Member (Idle past 1475 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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