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Author Topic:   Evidence that the Great Unconformity did not Form Before the Strata above it
edge
Member (Idle past 1706 days)
Posts: 4696
From: Colorado, USA
Joined: 01-09-2002


Message 1728 of 1939 (757526)
05-10-2015 12:46 AM
Reply to: Message 1727 by Faith
05-10-2015 12:09 AM


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.
Geologists are actually pretty good at thinking up alternatives. The point is that they search for evidence to support different schemes.
So they dismiss the idea of a fault on the unconformity line.
Based on the evidence, yes.
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.
Well, you have just seen a demonstration that they can.
Just wondering: Would you say the layered rocks in the picture are highly compacted?
Considering that it's very lithified, yes, I'd say it was compacted. Your point being?

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edge
Member (Idle past 1706 days)
Posts: 4696
From: Colorado, USA
Joined: 01-09-2002


Message 1729 of 1939 (757527)
05-10-2015 12:49 AM
Reply to: Message 1723 by Faith
05-09-2015 11:28 PM


Re: sedimentation on slope
I'm aware of the variations in thickness across huge distances. Nevertheless the impression of the strata over pretty huge distances, such as seen for instance from a distance in the Grand Canyon, is of a remarkable evenness of thickness.
Not in the case of the Tapeats which we see pinching out over short distances as shown by McKee.
Visible variations of thickness within a few hundred or even perhaps thousands of feet would suggest something other than normal deposition patterns to me.
And yet, they happen. Suggestions to you are not evidence.

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 Message 1730 by Faith, posted 05-10-2015 12:54 AM edge has replied

  
edge
Member (Idle past 1706 days)
Posts: 4696
From: Colorado, USA
Joined: 01-09-2002


Message 1731 of 1939 (757529)
05-10-2015 1:01 AM
Reply to: Message 1722 by Faith
05-09-2015 11:16 PM


Re: Sedimentation Video
ABE: I'll grant that there is more drape effect in the experiment than I would have expected, ...
Considering that you expected there would be no drape effect, yes, there is 'somewhat more'.
... but unlike the McKee drawings it's so evenly distributed it just comes off as thinly coating the slopes on the way down to pooling in the depressions, rather than forming draped layers as in the drawings.
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.
I know this seems picky but that's how it hits me. Maybe you need to get something more asymmetric to make your case. /ABE
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.
As for the draped sandstone I'm not sure how it should be set up. I DON'T see the same draped effect in the video experiment; I DON'T see sediment pooling in the depressions on the drawings, just draped layers.
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.
"Drape upon drape" means to me something more like layers of equal thickness that start thin at the top but drape down into the depressions with equal thickness like actual layers except they're draped, if that conveys anything. That's what I see in the McKee drawings. Maybe steeper "monadnocks" are needed for the experiment.
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?
In other words it's got to prove your argument or it's not worth it?
I think he is referring to your tendency to dismiss evidence and conclusions without explanations other than 'it kinda, sorta looks that way'.

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edge
Member (Idle past 1706 days)
Posts: 4696
From: Colorado, USA
Joined: 01-09-2002


Message 1732 of 1939 (757530)
05-10-2015 1:04 AM
Reply to: Message 1730 by Faith
05-10-2015 12:54 AM


Re: sedimentation on slope
Are you talking about variations in thickness from DEPOSITION or from deformation after deposition?
Seeing as there is no evidence of forced folding, it would be at deposition.
ABE: (interpretation) The geometry is from deposition./ABE
Forces, pressures, compaction after deposition can thin out a layer for instance.
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.

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edge
Member (Idle past 1706 days)
Posts: 4696
From: Colorado, USA
Joined: 01-09-2002


(1)
Message 1737 of 1939 (757575)
05-10-2015 10:13 PM


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:
quote:
"Figure 12--Three patterns of channel fill: A) horizontal layers, common in subaerial channels; B) layers conforming approximately to the channel shape, common in subaqueous channels; C) asymmetric fill by inclined layers, common in tidal regimes (from Reineck and Singh, l975, p. 63; based on McKee, l957)."
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.

  
edge
Member (Idle past 1706 days)
Posts: 4696
From: Colorado, USA
Joined: 01-09-2002


Message 1738 of 1939 (757649)
05-11-2015 6:17 PM


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

  
edge
Member (Idle past 1706 days)
Posts: 4696
From: Colorado, USA
Joined: 01-09-2002


Message 1739 of 1939 (757864)
05-14-2015 9:19 PM


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.

  
edge
Member (Idle past 1706 days)
Posts: 4696
From: Colorado, USA
Joined: 01-09-2002


Message 1741 of 1939 (757989)
05-17-2015 11:26 PM
Reply to: Message 1740 by snapdragon
05-17-2015 9:24 PM


Re: NY roadcut pictures
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 This item might not exist or is no longer available - OneDrive...
They may or may not be useful, but it was nice just to touch and see them firsthand.
Nice photos. Not sure if they resolve much of the discussion, but the 'gaps' seem to have disappeared, and still, we see no faults that penetrate across the unconformity. The lower white beach sand still appears draped across the irregular top of the gneiss. Thanks for the pictures.

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edge
Member (Idle past 1706 days)
Posts: 4696
From: Colorado, USA
Joined: 01-09-2002


Message 1767 of 1939 (760865)
06-26-2015 10:56 AM
Reply to: Message 1766 by JonF
06-26-2015 10:41 AM


Re: sedimentation on slope
It's preferable to unsupported claims from ignorant and incompetent people.
Not that I have any particular person in mind.
The temptation is great.
Give me strength.

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edge
Member (Idle past 1706 days)
Posts: 4696
From: Colorado, USA
Joined: 01-09-2002


(1)
Message 1795 of 1939 (761072)
06-27-2015 6:38 PM
Reply to: Message 1789 by Pressie
06-27-2015 11:32 AM


Re: sedimentation on slope
Somehow Faith doesn't realise that the geological time scale doesn't represent "layers". The geological time scale represents time periods.
This is another one of those unnecessary arguments that accomplishes nothing, but we commonly run into with Faith. It appears to me that Faith has confused the geological time scale with the 'geological column'.

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edge
Member (Idle past 1706 days)
Posts: 4696
From: Colorado, USA
Joined: 01-09-2002


(1)
Message 1802 of 1939 (761103)
06-28-2015 10:42 AM
Reply to: Message 1801 by Admin
06-28-2015 9:01 AM


Re: sedimentation on slope
If sand can form a slope, and if a slope of sand can become buried, and if the sand can become lithified, then how could strata forming while sloped be impossible?
Normally, I don't get into personal stories, but this discussion has reminded me of one of my first exposures to geology where the concept of original horizontality was introduced. I distinctly remember the professor saying that original horizontality is not absolute but could be used as a generalization for first-order interpretations. There are many cases of exception to the rule such as clastic fans (of which I think Dr. A provided an example image).
Now, maybe Faith knows better than my professors. After all, revealed truth always trumps learned truth.
Hey, it could be!

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edge
Member (Idle past 1706 days)
Posts: 4696
From: Colorado, USA
Joined: 01-09-2002


Message 1803 of 1939 (761104)
06-28-2015 10:53 AM
Reply to: Message 1800 by Pressie
06-28-2015 6:08 AM


Re: sedimentation on slope
edge, all YEC's writing on the subject deliberately confuse the geological time scale with local stratigraphic columns. They do it on purpose. To mislead.
Usually, I hate to declare a case of dishonesty when stupidity suffices. But your point is well taken, especially when the situation has been explained so many times.
Personally, I don't like the term 'geological column' and often place it in quotation marks, particularly where it confuses people. The problem is that this is a talking point for YECs. I like your use of 'stratigraphic columns' (empasizing the plural).

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edge
Member (Idle past 1706 days)
Posts: 4696
From: Colorado, USA
Joined: 01-09-2002


(1)
Message 1819 of 1939 (762152)
07-09-2015 11:21 AM
Reply to: Message 1817 by Admin
07-09-2015 8:33 AM


Re: Images from the Experiment
This doesn't make any sense. When deeply buried and under great pressure, what would prevent the area of the light sand layer that I've indicated from becoming lithified just like the rest of the layer?
If you magnify the highlighted area of the photograph, you will see another sedimentary feature that shows how sediments can be deformed shortly after deposition.
Note how the tan sand sinks into the underlying brown mud and the mud itself surges upward into the sand. These have a number of descriptive name such as 'ball and pillow' structures or sole marks. If we could see fine laminae in those pillows, they would be warped according to the flow of the sediments.
The point here is that these features formed almost immediately upon deposition and didn't wait until the 'entire sedimentary section' was deposited and lithified, as proposed by Faith in some of the earlier photographs that we have viewed in this and other threads.

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edge
Member (Idle past 1706 days)
Posts: 4696
From: Colorado, USA
Joined: 01-09-2002


Message 1820 of 1939 (762154)
07-09-2015 11:34 AM
Reply to: Message 1816 by JonF
07-09-2015 8:00 AM


Re: Images from the Experiment
Whatever you may have meant, you said many times that strata can only deposit horizontally.
Exactly true, and the equivocation we see going on now was predictable from the start.
If it were the case that strata could only be deposited horizontally, then the tan layer should pinch out against the brown layer. At least that's the way that it was always presented to us.

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edge
Member (Idle past 1706 days)
Posts: 4696
From: Colorado, USA
Joined: 01-09-2002


Message 1826 of 1939 (762222)
07-09-2015 4:37 PM
Reply to: Message 1821 by Faith
07-09-2015 2:14 PM


Re: Images from the Experiment
I'm afraid you've misread the image, edge. That's not mud, that's rather stiff dark gray nondrying clay that nothing could sink into. Although I did my best to get a tight fit between the clay and the sides of the container there was apparently enough space for the very fine sand to filter down between the clay and the container wall. I mention that in my description. It was one of the effects that spoiled the experiment.
Okay, I see. Nevertheless it does happen in nature.

This message is a reply to:
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Replies to this message:
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