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Author Topic:   Evidence that the Great Unconformity did not Form Before the Strata above it
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Message 331 of 1939 (753897)
03-23-2015 10:27 AM
Reply to: Message 271 by edge
03-22-2015 1:28 PM


edge writes:

Oh good grief. Why is this so difficul?. It wouldn't erode flat if it was tilted, but even if it was tilted it would be nothing like tilted STRATA.

But it is tilted. Do you know how I can tell? Do you think I would have shown you this picture if I didn't check?

I think it would be reasonable for Faith to ask for evidence that the strata are tilted.


--Percy
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Message 332 of 1939 (753898)
03-23-2015 10:29 AM
Reply to: Message 273 by Faith
03-22-2015 1:33 PM


Faith writes:

You've given a series of straw man answers. Nothing but denial and evasion. But what on earth could I possibly have expected here anyway? Masters of obfuscation.

Edge has provided what you requested, evidence of eroded tilted strata at the surface. If you actually wanted something different then could you please describe it?


--Percy
EvC Forum Director

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Message 333 of 1939 (753899)
03-23-2015 10:37 AM
Reply to: Message 282 by Faith
03-22-2015 3:04 PM


Faith writes:

However, you came up with some examples so you win.

This isn't a case of winning or losing, just a case of one point getting across from one side of the debate to the other, in this case that eroded tilted strata exist at the surface. I am, as I have said several times, responding as I read along, so I don't know where the discussion went after this, but we should be clear about what you're saying. Does this mean that there's now agreement that the Grand Uncomformity is an eroded surface?


--Percy
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Message 334 of 1939 (753900)
03-23-2015 10:41 AM
Reply to: Message 289 by herebedragons
03-22-2015 5:53 PM


Re: why can't erosion do it????????????
herebedragons writes:

I'm not sure this is the situation exactly. I am thinking that she is suggesting the the slip - folding is what caused the "perfectly" planar surfaces, rather than erosion. It is not a scenario you can find in any textbook, so it is something I was thinking about drawing up to show why it's not a feasible mechanism.

I think visual aids are making extremely valuable contributions to the discussion. If you can begin illustrating the mechanism Faith is describing, that could be very helpful.


--Percy
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edge
Member (Idle past 1022 days)
Posts: 4696
From: Colorado, USA
Joined: 01-09-2002


Message 335 of 1939 (753901)
03-23-2015 10:42 AM
Reply to: Message 315 by Admin
03-23-2015 8:06 AM


Re: Erosion simply CANNOT explain the flat contact line
And this description from Cambrian History of the Grand Canyon Region uses enough technical terms and unfamiliar references as to be indecipherable to many:

quote:
The principal points are as follows:
1. Weathering of the Archean rocks has extended downward 10 to 12 feet in many places and as far as 50 feet below the surface in some places.

Put simply, McKee (?) is saying that the surface effects of chemical weathering of rock extend well below the bedrock surface.

2. Weathering of Algonkian rocks has been slight, presumably because they are composed of minerals that have already survived at least one cycle of weathering.

Again, put simply, some of the rocks weather more slowly than others, probably due to mineralogy and how broken up they are.

etc...
etc...

To a trained person, these points are clear pretty clear. I'm glad someone is interested enough to ask.

What does it mean where it says that weathering has extended downward 10 to 12 feet? Does that mean that there's a dip in the surface of 10 to 12 feet. Of is that what it's referring to when it uses the term "weathered zone", and that the effects of weathering can be observed to a depth of 10 to 12 feet below the contact surface?

If it was eroded away, yes, the surface would depress by that amount. However, in this instance, it means that the chemical effects of weathering affect the bedrock to that depth but the rock is still intact.

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Message 336 of 1939 (753902)
03-23-2015 10:44 AM
Reply to: Message 290 by Faith
03-22-2015 6:03 PM


Re: why can't erosion do it????????????
Faith writes:

And I believe I do look at the big picture. Everybody else is looking at minuscule amounts of erosion between layers in my experience.

People may be wondering what you mean by this, particularly since the Grand Unconformity has been described a number of times as potentially representing a couple miles of missing material.


--Percy
EvC Forum Director

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Message 337 of 1939 (753904)
03-23-2015 10:50 AM
Reply to: Message 299 by Faith
03-22-2015 7:15 PM


Re: why can't erosion do it????????????
Faith writes:

I'm not explaining things again that were clear enough the first hundred times.

I am asking all participants to repeat clarifications and explanations as many times as necessary. About your claim of "the first hundred times" you explained things, the evidence shows you claiming many times that you've already explained something, but actual explanations seem much more rare.


--Percy
EvC Forum Director

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edge
Member (Idle past 1022 days)
Posts: 4696
From: Colorado, USA
Joined: 01-09-2002


Message 338 of 1939 (753905)
03-23-2015 10:50 AM
Reply to: Message 331 by Admin
03-23-2015 10:27 AM


I think it would be reasonable for Faith to ask for evidence that the strata are tilted.

Sometimes it would be good for someone to ask for an explanation. In this particular case, it could get into kind of a time-consuming, technical discussion relying on some visual interpretation that could be simply denied (of course, that never happens around here). But if someone really wants to know...

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herebedragons
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Posts: 1517
From: Michigan
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Message 339 of 1939 (753906)
03-23-2015 10:55 AM
Reply to: Message 315 by Admin
03-23-2015 8:06 AM


Re: Erosion simply CANNOT explain the flat contact line
You refer to Message 204, but that message wasn't making any arguments about non-flatness.

But it was. The description is of a weathered surface with cuts into it and structures that rose above it.

but some of the important details may not be getting across.

Yea, I get that. But if you look at Faith's response in Message 214, see only responds to the comment about quartzite not being metamorphic. I have no idea if she even read the rest of it. She has even stated she doesn't care about the details and that they are simply getting in the way of the discussion - or at least in the way of the point she is making. So I hope to eventually get back to some of the details in that post, but I'm not sure they would be helpful at this point.

from Message 316 An image of the monadnocks would be helpful.

They are hard to come by. There are so large that an image taken close up doesn't have the perspective and an image taken from far away doesn't have the detail. This image is the best example I could find of a monadnock.

I thought it was clear that the Shinumo Quartizite was the structure that protrudes through the Tapeats and so represents these so called monadnocks. Maybe not though, if you didn't catch it.

As you can see, it's not a cut and dried image, it takes some interpretation. And for sure, if there hadn't been a description that explained it, I wouldn't have picked it out. I also note that my interpretation might not be entirely accurate, if you want to look at it a bit closer and see if you agree with me? My concern was the brown band at the top of the Shimuno, it appears it might be Tapeats and this may not be the proper perspective to show the place where the Tapeats is missing.

Also, the grain is not completely clear from this distance, I think mostly because of the erosion that has created those vertical cuts. I do believe that the layer slopes upward from right to left. The slope of the Supergroup appears to much lower in this area than in some others where it can be up to 45 degrees.

from Message 316 Just to clarify, Faith doesn't believe the Great Unconformity was produced through sedimentation or erosion. She believes that tectonic forces caused it to rotate. Regarding non-angular unconformities, I believe Faith's denies that they are unconformities, denies evidence of erosion, and claims continuous sedimentation.

I thought as much, and I pressed her to spell it out so I would not mischaracterize her arguments. It is difficult to find illustrations of this concept so I am preparing a series of my own drawings to illustrate both how erosion CAN wear a surface flat and how the idea of rotating blocks under a stack of strata cannot work (or at least is not supported by observations). I will post them as soon as I can.

from Message 318 Might it be helpful to explain how a landscape came to be underlain by both harder and softer materials?

Hopefully my explanation of of how erosion can make a lumpy surface flat will help explain this. I will be sure to includes some details related to that as well.

But, I don't think it's worth spending time on complicated details until we can establish those basic principals.

HBD

Edited by herebedragons, : new link to image


Whoever calls me ignorant shares my own opinion. Sorrowfully and tacitly I recognize my ignorance, when I consider how much I lack of what my mind in its craving for knowledge is sighing for... I console myself with the consideration that this belongs to our common nature. - Francesco Petrarca

"Nothing is easier than to persuade people who want to be persuaded and already believe." - another Petrarca gem.

Ignorance is a most formidable opponent rivaled only by arrogance; but when the two join forces, one is all but invincible.


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edge
Member (Idle past 1022 days)
Posts: 4696
From: Colorado, USA
Joined: 01-09-2002


Message 340 of 1939 (753907)
03-23-2015 10:58 AM
Reply to: Message 330 by Admin
03-23-2015 10:25 AM


I am, as I said, gradually reading and responding through the thread. Your last three posts contain precisely what I suggested might be helpful a little earlier this morning, thank you. For this particular image, could you clarify what in the image indicates that the layers are tilted?

Not having been there, I'm not exactly sure what the rock type is, but I think you can see the layering which tilts steeply to the left toward the sea. The large flat surfaces face toward the sea and stand at about a 50 degree angle. Those surfaces are cut off at the top where a soil is developed and humans have constructed a lighthouse.

On the lower elevations, at wave level, you can see another flat bench starting to develop. Someday if it is uplifted, it will also develop a soil and someone will build on it. The current lighthouse, of course, will be eroded away...

Edited by edge, : No reason given.


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Message 341 of 1939 (753908)
03-23-2015 11:00 AM
Reply to: Message 304 by Faith
03-22-2015 7:40 PM


Re: why can't erosion do it????????????
Faith writes:

THE FRUSTRATION COMES FROM PEOPLE NOT READING WHAT I WRITE AND NOT THINKING AND IMPUTING RIDICULOUS NOTIONS TO ME.

Please leave moderation to the moderators. If you have specific complaints or issues please take them to the Report Discussion Problems Here 4.0 thread. I'm requesting that all participants clarify and explain as often as necessary.


--Percy
EvC Forum Director

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Message 342 of 1939 (753909)
03-23-2015 11:08 AM
Reply to: Message 309 by Faith
03-22-2015 7:53 PM


Re: why can't erosion do it????????????
Faith writes:

You aren't understanding the simplest most obvious things and I can't stand it any more.

In case it hasn't been clear from my previous messages, I'd like to encourage responses that seek to clarify and explain rather than blame.


--Percy
EvC Forum Director

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Message 343 of 1939 (753910)
03-23-2015 11:10 AM
Reply to: Message 312 by edge
03-22-2015 11:12 PM


edge writes:

Zoom in on the yellow highlight line in the upper left and you can see the layering in the outcrops.

Does Faith know about Ctrl-+, etc.?


--Percy
EvC Forum Director

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 Message 312 by edge, posted 03-22-2015 11:12 PM edge has not replied

  
AdminAsgara
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(1)
Message 344 of 1939 (753925)
03-23-2015 12:28 PM
Reply to: Message 341 by Admin
03-23-2015 11:00 AM


Re: why can't erosion do it????????????
Just stepping in here for a moment.

Faith continually claims that erosion can not and did not create the GC features discussed throughout this thread.

I suggest that Faith give us her description of exactly what erosion is and what it does to a land form. Explain why it can't make a flat surface instead of just repeating that it can't.

Maybe she can include some images of exactly what she thinks erosion will do to the surfaces discussed.


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Faith 
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Message 345 of 1939 (753949)
03-23-2015 3:00 PM


G U too flat to be eroded: images
Googled "erosion" to get some images to explain why I think years of erosion would never produce a flat surface. None of these address the situation at the contact of the Great Unconformity with its lumpy schist or tilted strata base, but it clearly has severe enough effects on flatter surfaces. And if you did get a flattish surface from the erosion of those very bumpy surfaces, the sort of thing shown in the pictures should be expected to happen at that point to that flatter surface.

However, the Great Unconformity contact is amazingly straight and level, flat and horizontal, much more so than the surfaces in any of the pictures put up by HBD and edge recently. Go to my Message 213 and Message 313 to see what I mean.

{Also note that in 213 that I did say which kind of surfaces are already flat or "depositional" surfaces as edge prefers I call them: I mentioned the Kaibab plateau and the tops of buttes, mesas, tepui. To make it clear the problem is not with those but with the very irregular kind of rock that is clearly very flat at the G.U. in the pictures I posted. }


Replies to this message:
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