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Author Topic:   Evidence that the Great Unconformity did not Form Before the Strata above it
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Message 2 of 1939 (752803)
03-13-2015 7:24 AM


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Message 314 of 1939 (753871)
03-23-2015 7:32 AM


Moderator On Duty
This morning will be reading through the hundred or so posts since I last checked in on Saturday, and I'll respond as I read. In many cases I may be noting an issue that has been resolved or is no longer relevant, so please just bear with me.

--Percy
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Message 315 of 1939 (753872)
03-23-2015 8:06 AM
Reply to: Message 217 by herebedragons
03-21-2015 4:09 PM


Re: Erosion simply CANNOT explain the flat contact line
herebedragons writes:

Faith writes:

And I'd ask the same question about the actual contact line there as well, which can only be seen when the whole context is included in the picture

But it's not flat, that was the point of Message 204 which the only thing you took out of that was the point about quartzite. Go back and read the rest of the post that describes the contact surface.

You refer to Message 204, but that message wasn't making any arguments about non-flatness. It had this image, where all the contact surfaces appear to be flat (also, the angular conformity between the Shinumo Quartzite and the Bright Angel Shale isn't apparent, I assume because from this angle the unconformity is in a frontal rather than side orientation):

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.
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.
etc...
etc...

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?

I'm going to try to draw an analogy to the problem faced by those arguing that the Great Unconformity represents an eroded surface. Images like this would seem like undeniable evidence of tilted layers being eroded flat:

I'll draw an analogy to a car accident, where images like this would seem like undeniable evidence of a car accident:

What does one do in response to denials that this image proves there was a collision between two vehicles. Once one overcomes the initial bewilderment at the denial of the apparently obvious, one is forced to draw upon other more technical evidence, say by quoting from the report of an expert analyst: "Analysis of the detritus is consistent with fragmentation caused by a serendipitous confabulation." Huh?

In other words, I think you're making your case very well with all the appropriate images and explanations, but some of the important details may not be getting across.


--Percy
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Message 316 of 1939 (753873)
03-23-2015 8:21 AM
Reply to: Message 221 by herebedragons
03-21-2015 5:01 PM


Re: Erosion simply CANNOT explain the flat contact line
herebedragons writes:

quote:
(From Message 204) The maximum height of these monadnocks in the Shinumo quadrangle he gives as 600 feet. Schuchert,” after visiting an area farther east, refers to hills up to 700 feet, and Wheeler and Kerr “’ describe one north of Grand Canyon Village which rises approximately 800 feet above the base of the Tapeats sandstone.

These monadnocks are in the same general area as that photograph. Not flat.

An image of the monadnocks would be helpful.

In Message 205, I showed an image with 4 unconformities. How would any of those unconformities form during continuous sedimentation WITHOUT erosion?

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.


--Percy
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Message 317 of 1939 (753874)
03-23-2015 8:25 AM
Reply to: Message 224 by Faith
03-21-2015 5:22 PM


Re: Erosion simply CANNOT explain the flat contact line
Faith writes:

IT SHOULDN"T BE FLAT ANYWHERE! NOT ANYWHERE! IT'S A LUMPY BUMPY POKY SPIKY IRREGULAR SURFACE. IT SHOULD NOT ERODE FLAT ANYWHERE, LET ALONE AS FLAT AS YOU CAN SEE IT IS IN THE PHOTOS I POSTED.

I think more discussion about what erosion does to a landscape would be worthwhile.


--Percy
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Message 318 of 1939 (753875)
03-23-2015 8:32 AM
Reply to: Message 227 by herebedragons
03-21-2015 5:50 PM


Re: Erosion simply CANNOT explain the flat contact line
herebedragons writes:

It has monadnock structures just like the ones I have been describing in the Great Unconformity.

This is a good example of how erosion, which tends to abrade landscapes flat, can produce a lumpy surface due to differential hardness. In this case what you're calling monadnocks have not been eroded because they're composed of harder material that perhaps goes all the way through or perhaps just caps the top.

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


--Percy
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Message 319 of 1939 (753876)
03-23-2015 8:38 AM
Reply to: Message 234 by Faith
03-21-2015 6:47 PM


Re: Erosion simply CANNOT explain the flat contact line
Faith writes:

Sure seems like an argument going on here to me. But now you are nitpicking. "FOLLOW THE TRAIN OF THOUGHT" then. Good grief.

I'm finding your train of thought difficult to follow. Clearly you think that people haven't followed your arguments properly and that the rebuttals therefore aren't relevant, but this just as clearly indicates that your arguments require clarification.


--Percy
EvC Forum Director

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Message 320 of 1939 (753877)
03-23-2015 8:42 AM
Reply to: Message 236 by Faith
03-21-2015 7:10 PM


Moderator Request
Faith writes:

Never mind. I know what you'll say and I don't want to get into that right now.

This is the total content of your post, which wasn't addressed to anyone.

I'd like to hope that all participants will continue to make a big effort in keeping this thread focused and constructive.


--Percy
EvC Forum Director

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Message 321 of 1939 (753878)
03-23-2015 8:52 AM
Reply to: Message 241 by Faith
03-21-2015 7:35 PM


Re: Erosion simply CANNOT explain the flat contact line
Faith writes:

I'm trying to follow your argument, but it doesn't make sense. You say that the unconformity is 'flat', even though it isn't.

Look at the pictures for a definition of "flat."

Many different images have been presented, so it's not possible to tell which you're referring to. Perhaps you could clarify the point you're trying to make here, using images if necessary.


--Percy
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Message 323 of 1939 (753880)
03-23-2015 8:58 AM
Reply to: Message 242 by edge
03-21-2015 7:40 PM


Re: Erosion simply CANNOT explain the flat contact line
edge writes:

Several lines of evidence have been shown to you that the Great Unconformity is not flat. Even by your pictorial definition.

I think the full argument has to be repeated at intervals. I'm trying to avoid becoming part of the discussion, but I'll briefly summarize my own understanding here and say that the Great Unconformity is not flat because on a large scale the different layers of the supergroup have different hardnesses and will therefore erode at different rates, and on a small scale that local conditions vary such as having ponds and rivers, or being more arid or more wet, or degree of elevation and exposure.


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Message 324 of 1939 (753881)
03-23-2015 9:05 AM
Reply to: Message 243 by Faith
03-21-2015 7:43 PM


Re: Erosion simply CANNOT explain the flat contact line
Faith writes:

I can't continue this discussion. This is nonsense. Just TRY to get what I'm saying. Somebody shoot me.

If you've been reading my comments, I've been encouraging everyone to clarify and even repeat their arguments as often as necessary.


--Percy
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Message 325 of 1939 (753882)
03-23-2015 9:13 AM
Reply to: Message 246 by Faith
03-21-2015 8:15 PM


Re: Erosion simply CANNOT explain the flat contact line
Faith writes:

YOU DON'T HAVE EVIDENCE EITHER. YOU THINK IT COULD AND THAT'S THAT. HOW DO YOU KNOW EROSION COULD DO THIS?

Maybe this is something the discussion needs to focus on. Jar has repeatedly made the point that erosion wears material from high places and carries it to low places, thereby flattening a landscape. If you don't accept this then I think you need to make that clear so it can be discussed.

THERE ARE LUMPY ROCKS WITH FLAT SURFACES.

An image of "lumpy rocks with flat surfaces" might be a helpful clarification.


--Percy
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 Message 246 by Faith, posted 03-21-2015 8:15 PM Faith has not replied

  
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Message 326 of 1939 (753886)
03-23-2015 9:20 AM
Reply to: Message 251 by Faith
03-22-2015 12:38 AM


Re: Erosion simply CANNOT explain the flat contact line
Faith writes:

If you had bothered to read what I wrote you'd know that I was talking about the impossibility of eroding down to flatness tilted surfaces like the angular strata of an angular unconformity and lumpy surfaces like schist and granite, and specifically said I was NOT talking about naturally FLAT surfaces like the Kaibab which is the upper surface of a limestone layer. I SAID THAT IN SO MANY WORDS. Sheesh.

Though I searched, I couldn't find where you said this in so many words, at least not recently.

I continue to urge everyone to clarify or repeat arguments as often as necessary.

Nobody here reads carefully, nobody thinks.

Please, no accusations aimed at the other side.

After I finish catching up today I'm going to object to all claims in any way similar to, "I already told you." There's far too much of this.


--Percy
EvC Forum Director

This message is a reply to:
 Message 251 by Faith, posted 03-22-2015 12:38 AM Faith has not replied

  
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Message 327 of 1939 (753887)
03-23-2015 9:23 AM
Reply to: Message 252 by Faith
03-22-2015 12:40 AM


Re: Erosion simply CANNOT explain the flat contact line
Faith writes:

No, there is no evidence of how they got that way, it's all fantasy.

It shouldn't be necessary to remind participants that bald declarations like this are inappropriate and unhelpful.


--Percy
EvC Forum Director

This message is a reply to:
 Message 252 by Faith, posted 03-22-2015 12:40 AM Faith has not replied

  
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Message 328 of 1939 (753888)
03-23-2015 9:32 AM
Reply to: Message 261 by edge
03-22-2015 12:59 PM


Re: Erosion simply CANNOT explain the flat contact line
edge writes:

That's Siccar Point. It has both upper and lower strata. What I'm saying is that the lower were not eroded flat before the upper were deposited on it.

Well, that's pretty obvious from the picture. The point is that this surface is demonstrably caused by erosion.

Presenting the image again:

What evidence in this image indicates that the boundary traced by the yellow line was caused by erosion?

To prove that's possible you need to find uptilted strata somewhere that have been eroded flat but without anything deposited on it.

Why would I need to do that? It's your point, not mine.

Faith would like photographic evidence of an angular unconformity at the surface, i.e., one where there's only sky above the unconformity. If I understand her correctly, that's all that's preventing her acceptance that the Grand Unconformity is an erosional surface.


--Percy
EvC Forum Director

This message is a reply to:
 Message 261 by edge, posted 03-22-2015 12:59 PM edge has replied

Replies to this message:
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