Register | Sign In


Understanding through Discussion


EvC Forum active members: 65 (9162 total)
1 online now:
Newest Member: popoi
Post Volume: Total: 915,818 Year: 3,075/9,624 Month: 920/1,588 Week: 103/223 Day: 1/13 Hour: 0/1


Thread  Details

Email This Thread
Newer Topic | Older Topic
  
Author Topic:   Origin of the Flood Layers
edge
Member (Idle past 1706 days)
Posts: 4696
From: Colorado, USA
Joined: 01-09-2002


Message 289 of 409 (753384)
03-19-2015 1:55 PM
Reply to: Message 275 by Faith
03-19-2015 12:00 PM


OK but that leaves the striping, which is pretty unusual whatever their colors.
Normal tilted bedding with intensive erosion.
Where else does that phenomenon appear?
You mean like here in Nevada?
Perhaps it does somewhere but that formation in China hit me like something from another planet when I first saw it and I've still not seen anything comparable anywhere else.
I dare say that there are a lot of things on this planet that you have not yet seen. And, of course, the gaudy colors are attention grabbers.
You said something about photos from Mexico though -- perhaps something similar there?
There are lots of similar locations, but all are somewhat different, so I doubt you would accept any photos that I have.
AND the main thing about the formation in relation to what I've been saying isn't the color anyway but the way the sandstone looks like it was squeezed out of a tube.
And I noticed the other day that the rocks along the highway looked like they formed in the same way as the paving operation going on between here and Boulder. So, that must be it: continental paving.
Nobody ever talks about sandstone as having a viscous quality at any stage of wetness that I know of, but both the Chinese formation and that picture of the Tapeats with the quartz chunks stuck in it suggest something along those lines.
I know what you mean. The flat-lying sandstones look like the layers laid down by the paving company. I'll work on this theory a little bit more tonight, but in the meantime, it seems plausible.
So does The Wave, but that's the only other one I can think of.
There are more things out there than you can imagine...

This message is a reply to:
 Message 275 by Faith, posted 03-19-2015 12:00 PM Faith has replied

Replies to this message:
 Message 290 by Faith, posted 03-19-2015 2:03 PM edge has replied

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


Message 292 of 409 (753392)
03-19-2015 2:16 PM
Reply to: Message 284 by Faith
03-19-2015 12:56 PM


Would somebody please explain the significance of "this point?"
It's where the picture was taken.
All I see is a trench left after the vein of quartz was removed from it.
I do not see a trench, nor a vein. Those are fragments of a vein or intrusive.
That's how it LOOKS to me. It still looks that way. Somebody will have to show clearly that it's better explained some other way, and probably show me on the photo itself.
Do you understand cross-sections?
All I can say is that it just doesn't LOOK LIKE that to me.
I understand. That's why I'm proposing the continental paving theory.
The "pebbles" don't look like they are sitting, they look like they are stuck in the sandstone and suspended above a depression out of which they came.
I have shown you where they came from. It doesn't look like this picture.
OK, that's something to wonder about. But what, in your opinion, explains that vertical edge of the sandstone in which the quartz is stuck?
Probably just a fracture surface modified by erosion. Hard to tell in a photograph like this.
But the point is moot anyway.
We know that there have been faults and erosion prior to deposition of the Tapeats based on superposition, cross-cutting features and the fragmentation of the pegmatite.
No comprendo Senor.
Never mind. It's an esoteric point anyway.
That's what the evidence I just gave you shows until something shows me I'm misreading it.
The evidence shows that the clasts came from various veins and dikes, not from irregular depressions in the Vishnu that just happened to be at the contact between the Vishnu and overlying Tapeats.
If you are talking about the picture in Message 247, no, they look like veins of quartz in a wall of schist. If something caused the quartz to come out of their veins then they might look like clasts either lying on the schist or stuck in sandstone and not lying on anything.
And that would be erosion...

This message is a reply to:
 Message 284 by Faith, posted 03-19-2015 12:56 PM Faith has not replied

Replies to this message:
 Message 334 by Admin, posted 03-20-2015 10:22 AM edge has not replied

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


Message 293 of 409 (753393)
03-19-2015 2:21 PM
Reply to: Message 290 by Faith
03-19-2015 2:03 PM


Thank you for the picture of the formation in Nevada. It's striped like the Chinese formation and curved like the Wave and I hadn't known about it.
The carved formation at the bottom is a different kind of thing than I'm talking about.
I don't think you've said anything to explain the appearance of viscosity in either the Danxia formation -- especially those barrel-shaped forms lying on their side in a row -- or the Tapeats we've been discussing. Neither is "normal tilted bedding."
I don't know what to tell you. I see continuous bedding in very soft sedimentary rocks that have been eroded into rather fanciful forms. In the foreground the bedding is vertical and in the distance it is tilted to the left.
In the descriptions of the site, there is nothing abnormal except the presence of pseudokarst, but I've seen that elsewhere too.

This message is a reply to:
 Message 290 by Faith, posted 03-19-2015 2:03 PM Faith has not replied

Replies to this message:
 Message 336 by Admin, posted 03-20-2015 10:26 AM edge has not replied

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


Message 294 of 409 (753394)
03-19-2015 2:24 PM
Reply to: Message 291 by JonF
03-19-2015 2:15 PM


The point is that there are many pictures of many locations where the Tapeats contacts the Vishnu and clasts are in the Tapeats and the near-vertical face of the Tapeats is obviously from erosion and not from magic flowing sandstone.. I'm not going into a long explanation, I've been down that road before. Perhaps someone else will.,
It would seem fruitless and rather unnecessary. There is ample evidence without getting into the details of photographs which have odd artifacts due to lighting and lack of depth.

This message is a reply to:
 Message 291 by JonF, posted 03-19-2015 2:15 PM JonF has not replied

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


(2)
Message 297 of 409 (753398)
03-19-2015 2:55 PM
Reply to: Message 272 by JonF
03-19-2015 11:28 AM


{ABE} I sure don't see any way to interpret this as a fluid sandstone [sic] flowing across and stopping at the Vishnu. Pretty obviously both were eroded to expose this cross-section. Note the clasts in the sandstone.
I'm not sure it's clear to Faith, but this is the exact location where her photograph of the unconformity came from.
Thank you for tracking this down.

This message is a reply to:
 Message 272 by JonF, posted 03-19-2015 11:28 AM JonF has replied

Replies to this message:
 Message 299 by JonF, posted 03-19-2015 4:12 PM edge has replied

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


Message 298 of 409 (753401)
03-19-2015 3:18 PM
Reply to: Message 295 by JonF
03-19-2015 2:33 PM


Re: HOW I KNOW IT'S A DEPRESSION AND NOT A SHADOW
I'm trying to find an image of the granite dikes terminating against the unconformity and forming a pebble trail along the unconformity. This one isn't quite what I wanted, but it does show the relationship of the dikes (the irregular pink lines on the black wall) being cut off by the unconformity. They do not extend upward into the flat-lying sedimentary rocks.

This message is a reply to:
 Message 295 by JonF, posted 03-19-2015 2:33 PM JonF has not replied

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


Message 300 of 409 (753427)
03-19-2015 6:44 PM
Reply to: Message 299 by JonF
03-19-2015 4:12 PM


Nicelyl labeled. Except for the misspelling. :-)
New geological term.

This message is a reply to:
 Message 299 by JonF, posted 03-19-2015 4:12 PM JonF has not replied

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


(1)
Message 309 of 409 (753447)
03-20-2015 12:37 AM
Reply to: Message 308 by Faith
03-20-2015 12:20 AM


Of course, erosion going on NOW since they were exposed. But that totally glosses over the important questions how LONG they were exposed, whether the currently exposed Vishnu was ever covered by the Tapeats, and whether any buried surfaces ever were exposed to the surface.
Faith, you do realize that you are not making any sense here, right?
As for this picture, I don't care what it is supposed to represent, it's so frustrating to have my observations dismissed out of hand at the moment I don't feel like continuing any of this discussion.
Well, you could try being reasonable...
I have to say that this is the funniest post I've seen in a long time. It does more to destroy YEC than anything we could have written. Please, keep up the good work.

This message is a reply to:
 Message 308 by Faith, posted 03-20-2015 12:20 AM Faith has not replied

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


(2)
Message 312 of 409 (753451)
03-20-2015 12:50 AM
Reply to: Message 310 by herebedragons
03-20-2015 12:44 AM


Is not the Grand Canyon composed of layers? Is not the Tapeats the lowest layer of the Paleozoic group? Wouldn't that mean there were layers on top of it?
Faith has not grasped that, if the Vishnu was never covered by other sediments, then it has been eroded since even before the Tapeats was deposited. That, of course, contradicts her point that there was no erosion before the entire sedimentary sequence was deposited.
Standard YEC fare, but kind of entertaining in this case. And almost 100% predictable.

This message is a reply to:
 Message 310 by herebedragons, posted 03-20-2015 12:44 AM herebedragons has not replied

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


Message 313 of 409 (753452)
03-20-2015 12:51 AM
Reply to: Message 311 by Faith
03-20-2015 12:46 AM


Both of you guys aren't making any sense, sorry.
Heh, heh ...
Ummm, no apologies necessary.

This message is a reply to:
 Message 311 by Faith, posted 03-20-2015 12:46 AM Faith has not replied

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


Message 338 of 409 (753492)
03-20-2015 10:31 AM
Reply to: Message 331 by Admin
03-20-2015 10:02 AM


Re: Moderator Clarification
Though this is a reply to Faith, I'm actually just trying to draw attention to what Faith has been trying to say about the shadows beneath the clasts. I've circled what Faith sees as depressions in the Vishnu Schist in the image. Faith believes that the clasts used to be down in those depressions and were somehow "sucked up" into the Tapeats:
Thank you for translating these questions.
First of all, the shadows are there partly because the quartz pegmatites protrude out from the rock face which is nearly vertical as shown in the image with the geologist. Light coming from above necessarily casts a shadow beneath the fragments.
Second, if the pegmatite pebbles have an original position in the schist as dikes and veins, they would not look like fragments positioned in little depressions (which just happen to be directly on top of the unconformity, by the way). But maybe this isnt' clear...
What if we put those fragments back into their depressions. Would they look like dikes and veins?
She wants to know how pieces of quartz broken off from the veins of quartz embedded within the Vishnu Schist came to be deposited atop the Vishnu Schist.
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.
Does that help clarify things, because I'm not sure how to further explain it. The appearance of the fragments now is not in veins or dikes, and if they came from depressions in the schist surface that would not look like the veins or dikes either.
There may be some confusion here that the fragments are lying directly on the surface of the unconformity. This is not always the case. I believe there are some images out there showing pieces of the pegmatite farther up in the Tapeats, which is also something that we would expect.
I have looked far and wide to find an image where we might see a pegmatite dike running upward through the schist and terminating against the unconformity, and also showing a trail of pebbles spreading out along that erosional unconformity surface. Perhaps a drawing will suffice. Later.

This message is a reply to:
 Message 331 by Admin, posted 03-20-2015 10:02 AM Admin has replied

Replies to this message:
 Message 351 by Admin, posted 03-20-2015 11:16 AM edge has replied

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


Message 341 of 409 (753496)
03-20-2015 10:35 AM
Reply to: Message 337 by JonF
03-20-2015 10:28 AM


Sure don't look like it tome. Pockmarked, ridges, a bedding plane that Edge pointed out, definitely rough front surface.
I agree. Perhaps to someone not familiar with rocks, it looks like a flow of taffy or something draped over the schist, but 'smooth' surfaces are fairly common in geology.
Now, if I crashed my bike on that surface and skidded a a few feet, I would probably not characterize the surface as 'smooth'...

This message is a reply to:
 Message 337 by JonF, posted 03-20-2015 10:28 AM JonF has not replied

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


Message 343 of 409 (753498)
03-20-2015 10:43 AM
Reply to: Message 339 by Admin
03-20-2015 10:33 AM


Re: Moderator Info
Though I'm replying to Faith, I'm really just calling attention to something Faith believes that might be worth addressing. She indicates here her belief that rocks form by drying:
I read that post also, but couldn't, for the life of me, figure out what she means.
She talks about plucking out fragments of the dikes, but earlier suggested that they came from those 'depressions' in the schist.
If anything was 'sticky' at the time of deposition, it would be the schist. But, unfortunately for Faith, that would mean the the schist had been weathered at an erosional unconformity.
I'm waiting for clarification.

This message is a reply to:
 Message 339 by Admin, posted 03-20-2015 10:33 AM Admin has seen this message but not replied

Replies to this message:
 Message 345 by Faith, posted 03-20-2015 11:01 AM edge has not replied

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


Message 348 of 409 (753503)
03-20-2015 11:05 AM


Okay, I haven't found an example in the Grand Canyon, but perhaps this diagram will help to explain a little bit. It shows how a gold-bearing quartz vein is weathered to produce placer deposits of different types, depending on the degree of transport. If we just ignore the gold and accept that the quartz vein will be similarly distributed by weathering we have something similar to the quartz pegmatite on the unconfomity surface.
This important thing here is the process of erosion and transport that happens at the unconformity, meaning that the rocks are exposed to surficial processes.
Does this help?

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


Message 352 of 409 (753508)
03-20-2015 11:17 AM
Reply to: Message 349 by Admin
03-20-2015 11:05 AM


Re: Formation of schist etc.
Faith presented a pretty detailed description of what she thinks happened, so couldn't we consider that as her model? Anyway, naturally it raises some questions, which you go on to do.
Well, I'm not sure that I would call it a model. Perhaps we could call it an ad hoc, hypothetical scenario ... one that has been compromised on several accounts. We keep asking questions, but the only real response is that it looks like ... 'something', to one individual.

This message is a reply to:
 Message 349 by Admin, posted 03-20-2015 11:05 AM Admin has seen this message but not replied

Replies to this message:
 Message 353 by Faith, posted 03-20-2015 11:21 AM edge has not replied

  
Newer Topic | Older Topic
Jump to:


Copyright 2001-2023 by EvC Forum, All Rights Reserved

™ Version 4.2
Innovative software from Qwixotic © 2024