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Author Topic:   Origin of the Flood Layers
edge
Member
Posts: 3711
From: Colorado, USA
Joined: 01-09-2002
Member Rating: 1.7


Message 361 of 409 (753548)
03-20-2015 1:52 PM
Reply to: Message 359 by Faith
03-20-2015 12:46 PM


Look, I'd be happy enough if it was as shallow as you say because finding out the tiny scale of the image changed most of my view of it.
HOWEVER, as I analyze even your lightened version I still think that's a depression the clasts came out of. That IS the physical edge of a depression, not just the edge of the shadow that was originally there.

The lightened area is red on your image, and the edge, which I've marked in blue on my own copy of the image, is the color of the schist. The remaining shadow that is still visible under the clasts indicates that they are suspended over the depression.


So, if you are correct, we should be able to find similar occurrences within the Vishnu Schist. The occurrences should have a fragmented appearance with schist on both sides.

You may want to do this search, but I'm going to abstain for the time being (likely a very long time).

In the meantime, could you explain why we do not have these veins or dikes in the Tapeats?

The clasts still appear to be suspended above the depression.

Interesting observation. Why do you think that is that case? What does that material between the clast and the schist seem to be?

The lightened area where the shadow was is the schist at the bottom of the depression, it is not continuous with the surface.

Why do you suppose it looks different? Is there anything else you can say about that material?
This message is a reply to:
 Message 359 by Faith, posted 03-20-2015 12:46 PM Faith has responded

Replies to this message:
 Message 362 by JonF, posted 03-20-2015 2:02 PM edge has responded
 Message 369 by Faith, posted 03-20-2015 7:42 PM edge has responded

  
JonF
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Posts: 3483
Joined: 06-23-2003
Member Rating: 2.8


Message 362 of 409 (753550)
03-20-2015 2:02 PM
Reply to: Message 361 by edge
03-20-2015 1:52 PM


Interesting observation. Why do you think that is that case?

Well it sho' looks like that to me.

What does that material between the clast and the schist seem to be?

Looks like air from here.


This message is a reply to:
 Message 361 by edge, posted 03-20-2015 1:52 PM edge has responded

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edge
Member
Posts: 3711
From: Colorado, USA
Joined: 01-09-2002
Member Rating: 1.7


Message 363 of 409 (753551)
03-20-2015 2:04 PM
Reply to: Message 360 by JonF
03-20-2015 1:52 PM


It's the edge of the shadow that was originally there. It's the boundary between the un-lightened and lightened version.

Actually, I think it's a different material, also. The question is, what is it? It has something to do with the process of creating an unconformity.

Oh, the clasts are definitely slightly above the Vishnu surface. That's why your idea of encroaching sandstone picking them up off the Vishnu is so silly.

I don't have a problem with the clasts being transported, just not from those 'depressions', and probably not by the same flow regime that deposited the sandstone. And I don't think they were transported very far. The clasts are what I would call sub-angular, meaning that they have been transported a short distance, but more than simply plucked up and resettled in the same place.

You are also seeing something that is interesting to me. You are pointing out a fabric in the softer, shadowed material. How did that form and from what material? Does it look like sand?


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 Message 360 by JonF, posted 03-20-2015 1:52 PM JonF has responded

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edge
Member
Posts: 3711
From: Colorado, USA
Joined: 01-09-2002
Member Rating: 1.7


Message 364 of 409 (753553)
03-20-2015 2:09 PM
Reply to: Message 362 by JonF
03-20-2015 2:02 PM


Well it sho' looks like that to me.

Well, according to Faith that seals it. It 'looks like' is pretty solid evidence.

Looks like air from here.

I don't know if even Faith would think it was always air, but if the Vishnu at this location has always been exposed to the surface (never buried), you never know...
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JonF
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Posts: 3483
Joined: 06-23-2003
Member Rating: 2.8


Message 365 of 409 (753555)
03-20-2015 2:37 PM
Reply to: Message 363 by edge
03-20-2015 2:04 PM


You are also seeing something that is interesting to me. You are pointing out a fabric in the softer, shadowed material. How did that form and from what material? Does it look like sand?

Not sure what you mean by "fabric", and we don't know much from that photograph about the hardness. IMHO the shadowed area is Vishnu Schist, just a continuation of the un-shadowed area.


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 Message 363 by edge, posted 03-20-2015 2:04 PM edge has not yet responded

  
Admin
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From: EvC Forum
Joined: 06-14-2002
Member Rating: 1.9


Message 366 of 409 (753557)
03-20-2015 2:51 PM
Reply to: Message 354 by edge
03-20-2015 11:25 AM


Re: Moderator Clarification
Hi Edge,

Yeah, you got it, thanks for the clarifications.

You were wondering why I chose the scenario of a cliff face towering over a riverbed, and that was because you said, "Probably much the same way as they would look as if they fell out of the cliff face shown and ended up in the river sediments below," and the "cliff face shown" was this one:

So in my reply I tried to be consistent with that pictured scenario of a cliff face over a riverbed. I understand it doesn't have to be a cliff face, just a difference in height. But it's the difference in height combined with the transport that is a part of the scenario that I think many people will miss when you say that the material atop the Vishnu Schist is from the Vishnu Schist. I think many will assume you mean it came from that exact spot of the Vishnu Schist, or perhaps just be confused.

Also, the material coming off that cliff face can be from other layers above the Vishnu Schist. We can only see Vishnu Schist in that photo, but somewhere above out of view are other layers. It's another part of the potential confusion that when it is said about that clast photo that when clasts from the lower layer are found embedded in the layer above that it is evidence of an unconformity, many will conclude that you mean the clasts always have to be from that lower layer. They don't. They could be from some layer above that layer, and even possibly below that layer depending upon how "interesting" the geological history has been.


--Percy
EvC Forum Director

This message is a reply to:
 Message 354 by edge, posted 03-20-2015 11:25 AM edge has responded

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 Message 368 by edge, posted 03-20-2015 3:18 PM Admin has acknowledged this reply

    
Admin
Director
Posts: 12389
From: EvC Forum
Joined: 06-14-2002
Member Rating: 1.9


Message 367 of 409 (753560)
03-20-2015 2:57 PM
Reply to: Message 364 by edge
03-20-2015 2:09 PM


Moderator Request
Please use PM's if you want to discuss other participants and their contributions.

--Percy
EvC Forum Director

This message is a reply to:
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edge
Member
Posts: 3711
From: Colorado, USA
Joined: 01-09-2002
Member Rating: 1.7


Message 368 of 409 (753568)
03-20-2015 3:18 PM
Reply to: Message 366 by Admin
03-20-2015 2:51 PM


Re: Moderator Clarification
So in my reply I tried to be consistent with that pictured scenario of a cliff face over a riverbed. I understand it doesn't have to be a cliff face, just a difference in height.

Sure, all scenarios of topographic relief are valid, and they do happen.

But it's the difference in height combined with the transport that is a part of the scenario that I think many people will miss when you say that the material atop the Vishnu Schist is from the Vishnu Schist. I think many will assume you mean it came from that exact spot of the Vishnu Schist, or perhaps just be confused.

That is why I included that image of different types of placer gold deposits. There are differing degrees of transport.

And, there is little doubt in my mind that some of the material just above the unconformity is actually part of the schist itself.

Also, the material coming off that cliff face can be from other layers above the Vishnu Schist. We can only see Vishnu Schist in that photo, but somewhere above out of view are other layers. It's another part of the potential confusion that when it is said about that clast photo that when clasts from the lower layer are found embedded in the layer above that it is evidence of an unconformity, many will conclude that you mean the clasts always have to be from that lower layer. They don't. They could be from some layer above that layer, and even possibly below that layer depending upon how "interesting" the geological history has been.

Exactly. All Jon and I are saying is that if it is incorporated into the sand, its source is older than the sand; and since the sand is a product of erosion, then erosion must be occurring somewhere, probably at a higher elevation.
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 Message 366 by Admin, posted 03-20-2015 2:51 PM Admin has acknowledged this reply

  
Faith
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Posts: 23953
Joined: 10-06-2001
Member Rating: 1.0


Message 369 of 409 (753580)
03-20-2015 7:42 PM
Reply to: Message 361 by edge
03-20-2015 1:52 PM


You may want to do this search, but I'm going to abstain for the time being (likely a very long time).

Not much point in my sticking around either. When an argument is about an observation it helps to have others see the same thing along with you and I'm always just one against many.

In the meantime, could you explain why we do not have these veins or dikes in the Tapeats?

Takes heat and pressure I would expect, plus the fact that schist is made up of many rocks and minerals including those that form quartz or pegmatite veins.


This message is a reply to:
 Message 361 by edge, posted 03-20-2015 1:52 PM edge has responded

Replies to this message:
 Message 370 by edge, posted 03-20-2015 7:51 PM Faith has responded

    
edge
Member
Posts: 3711
From: Colorado, USA
Joined: 01-09-2002
Member Rating: 1.7


Message 370 of 409 (753582)
03-20-2015 7:51 PM
Reply to: Message 369 by Faith
03-20-2015 7:42 PM


Not much point in my sticking around either. When an argument is about an observation it helps to have others see the same thing along with you and I'm always just one against many.

Some kind of common observation is one of the main requirements of science. If you consistently see something different, could there be something wrong with your sensors? Or maybe your processing is out of calibration?

Takes heat and pressure I would expect, plus the fact that schist is made up of many rocks and minerals including those that form quartz or pegmatite veins.

Well, the geological level of the Tapeats isn't much different from the GC metamorphic suite: and the composition of the pegmatites is mostly quartz, so I'm not sure why the Tapeats would be exempt from forming such veins and dikes.

Do you think there could be an age difference?


This message is a reply to:
 Message 369 by Faith, posted 03-20-2015 7:42 PM Faith has responded

Replies to this message:
 Message 371 by Faith, posted 03-20-2015 8:00 PM edge has responded

  
Faith
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Posts: 23953
Joined: 10-06-2001
Member Rating: 1.0


Message 371 of 409 (753583)
03-20-2015 8:00 PM
Reply to: Message 370 by edge
03-20-2015 7:51 PM


Heat and pressure does it for me.

And no, I'm seeing the clasts and the depression correctly, you aren't.


This message is a reply to:
 Message 370 by edge, posted 03-20-2015 7:51 PM edge has responded

Replies to this message:
 Message 372 by edge, posted 03-20-2015 8:04 PM Faith has responded
 Message 373 by jar, posted 03-20-2015 8:06 PM Faith has responded
 Message 397 by JonF, posted 03-21-2015 8:48 AM Faith has not yet responded

    
edge
Member
Posts: 3711
From: Colorado, USA
Joined: 01-09-2002
Member Rating: 1.7


Message 372 of 409 (753584)
03-20-2015 8:04 PM
Reply to: Message 371 by Faith
03-20-2015 8:00 PM


Heat and pressure does it for me.

Does what for you?

And no, I'm seeing the clasts and the depression correctly, you aren't.

You don't even know what I think about the depressions. I've been careful about that...
This message is a reply to:
 Message 371 by Faith, posted 03-20-2015 8:00 PM Faith has responded

Replies to this message:
 Message 374 by Faith, posted 03-20-2015 9:47 PM edge has responded

  
jar
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Posts: 28424
From: Texas!!
Joined: 04-20-2004
Member Rating: 2.6


Message 373 of 409 (753585)
03-20-2015 8:06 PM
Reply to: Message 371 by Faith
03-20-2015 8:00 PM


how do you make heat and pressure?
Faith writes:

Heat and pressure does it for me.

So how do you make heat and pressure?

How do you get a layer made from very fine metamorphosed mudstone and shale below a layer of far more coarse sandstone?


Anyone so limited that they can only spell a word one way is severely handicapped!

This message is a reply to:
 Message 371 by Faith, posted 03-20-2015 8:00 PM Faith has responded

Replies to this message:
 Message 375 by Faith, posted 03-20-2015 9:49 PM jar has responded

  
Faith
Member
Posts: 23953
Joined: 10-06-2001
Member Rating: 1.0


Message 374 of 409 (753590)
03-20-2015 9:47 PM
Reply to: Message 372 by edge
03-20-2015 8:04 PM


One of the many difficulties of trying to have a discussion with you is that you NEVER read in context. Heat and pressure does it for me without the factor of great age, about which you had just asked me. Does that clarify or do I need to copy out every quote, even the most recent? I guess I could do that but since this is only one of many difficulties I don't expect it to be worth the time anyway.

You don't even know what I think about the depressions. I've been careful about that...

OK, but didn't you just respond to JonF by suggesting that the material in the depression / shadow is not schist?

And please make something else clear: You called the clasts "boulders" at one time, and referred to that little ridge in the Tapeats as a "bedding plane." Did you see Percy's post since then that showed the area of this photo to cover about twenty 100 square inches? ABE: About nine by twelve or so, judging by the size of the woman's hand in Message 322 ./ABE

Edited by Faith, : No reason given.

Edited by Faith, : No reason given.


This message is a reply to:
 Message 372 by edge, posted 03-20-2015 8:04 PM edge has responded

Replies to this message:
 Message 379 by edge, posted 03-20-2015 10:38 PM Faith has responded

    
Faith
Member
Posts: 23953
Joined: 10-06-2001
Member Rating: 1.0


Message 375 of 409 (753591)
03-20-2015 9:49 PM
Reply to: Message 373 by jar
03-20-2015 8:06 PM


Re: how do you make heat and pressure?
I explained the heat and pressure back in that lengthy description I gave of the scenario I have in mind that Percy suggested you should take as my model.

As for the question about the laying down of different sediments let's not change the subject, OK?


This message is a reply to:
 Message 373 by jar, posted 03-20-2015 8:06 PM jar has responded

Replies to this message:
 Message 377 by jar, posted 03-20-2015 10:08 PM Faith has responded

    
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