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Author Topic:   Evidence that the Great Unconformity did not Form Before the Strata above it
Percy
Member
Posts: 20398
From: New Hampshire
Joined: 12-23-2000
Member Rating: 4.7


(2)
Message 38 of 1939 (752885)
03-14-2015 9:31 AM
Reply to: Message 1 by Faith
03-12-2015 12:42 PM


Hi Faith,

I don't see you saying anything new in this thread. These are the same arguments you've made in previous Grand Canyon discussions.

This has been pointed out before in this thread (and countless other threads), but your view of what happened is impossible because it requires cubic miles of rock to just disappear. The layers in this diagram represent the layers in the Grand Canyon region as you imagine them before the uplift. The sky blue layer represents the top layer of the supergroup, the tan base is the Vishnu Schist:

You propose that tectonic forces tilted just the supergroup layers and not those above to form this:

This is impossible because it requires cubic miles of rock to just disappear. The sky blue layer and the layers beneath it represent cubic miles and miles of rock, and apparently in your view most of these layers with their cubic miles of rock just disappears. That is impossible.

The Grand Canyon Supergroup is the remains of an ancient and typical basin and range formation that occurs as a region is stretched:

We can tell that the region became elevated because this basin and range composed of supergroup layers was then eroded flat, the layers of the supergroup completely disappearing in many areas. Subsidence and/or rising seas or some combination caused the region to become submerged and marine layers began depositing atop the tilted supergroup layers, starting with the Tapeats.

--Percy

Edited by Percy, : Typo.


This message is a reply to:
 Message 1 by Faith, posted 03-12-2015 12:42 PM Faith has responded

Replies to this message:
 Message 41 by Faith, posted 03-14-2015 11:08 AM Percy has responded
 Message 52 by edge, posted 03-14-2015 1:35 PM Percy has acknowledged this reply

  
Percy
Member
Posts: 20398
From: New Hampshire
Joined: 12-23-2000
Member Rating: 4.7


Message 43 of 1939 (752901)
03-14-2015 12:29 PM
Reply to: Message 41 by Faith
03-14-2015 11:08 AM


Faith writes:

Well I had hope for it as proof that the G.U. was not formed before the strata above it, which IS a new emphasis.

It isn't new. Your claim has always been that the layers of the supergroup and all the layers above them were deposited at the same time by the flood.

Nobody is really addressing that factor though, some insisting on making a case for the strata to be laid down over a mound, though even Geology doesn't make that claim, they recognize the mound as an uplift that came later.

In Message 3 and Message 6 PaulK does appear to be saying that the layers were deposited after the uplift. Since that's absurd he must be saying something else. Marine layers could not possibly have been deposited on a terrestrial uplift. I don't know what contours he's referring to when he says, "First it is possible for sediment to drape over existing contours provided friction and adhesion are sufficient to keep it in place." What he says is true in some contexts, but if he's referring to your diagram where you show layers butting up against the sides of the Grand Unconformity, then no.

Calling the uplift a "mound" is misleading. The tilt is very, very gradual. The exaggeration of the vertical direction of most diagrams has already emphasized repeatedly in this thread.

The idea was that SINCE the strata didn't follow the contour of the mound, if the G.U. was there first they would have to butt into it. Since they didn't butt into it that's evidence it wasn't there first.

As all diagrams clearly show, the top of the tilted G.U. was eroded fairly flat before more layers were deposited atop it. The differences in radiometric dates make clear that the formation of the G.U. was followed by an immense timespan before the formation of the layers above.

--Percy


This message is a reply to:
 Message 41 by Faith, posted 03-14-2015 11:08 AM Faith has responded

Replies to this message:
 Message 45 by Faith, posted 03-14-2015 12:45 PM Percy has responded
 Message 48 by Faith, posted 03-14-2015 12:52 PM Percy has responded

  
Percy
Member
Posts: 20398
From: New Hampshire
Joined: 12-23-2000
Member Rating: 4.7


(5)
Message 88 of 1939 (752970)
03-15-2015 9:17 AM
Reply to: Message 45 by Faith
03-14-2015 12:45 PM


Faith writes:

I recalculated the rise of the mounded area. It's a rise of 160 feet in one mile. Pretty shallow but still I don't see how layers are going to follow its contour.

No one is claiming the uplift was already present when the layers were deposited, but that's only a 3% slope. Take a foot-long ruler, lie it on a table surface, put a pencil under one end. That's a 3% slope. Layers will have no problem accumulating on such a mild slope.

You said this in Message 44:

Unfortunately for you all the evidence shows that the Great Unconformity was laid down before the layers above it

Except the evidence I'm giving.

You're not providing any evidence. Obviously you think you are, so what is it? In your Message 1 you didn't describe any new evidence, just "THINGS TO NOTICE" that were incredibly obvious. Not only had everyone already noticed them, they've been discussed, with you, in previous threads.

As all diagrams clearly show, the top of the tilted G.U. was eroded fairly flat before more layers were deposited atop it.

I always find that idea as absurd as the idea that the strata would conform to the slope of a hill.

That's your problem if you find absurd the process of erosion gradually flattening landscapes. It's a process we can see occurring in the world today, and one we find has happened enumerable times in the past.

Normal erosion doesn't reduce sharply tilted rock to a flat plain in my experience.

Erosion erodes whatever is there, whether it's been tilted from its original orientation or not. Look at this diagram of the formation of a basin and range again:

Look at the last step in the process, the bottom drawing. This is a typical basin and range. The highest parts of the exposed top portions of the tilted blocks form mountain ranges. The lowest parts of the exposed top portions of the tilted blocks form valleys. Here's my own rendition of the last stage in the formation of basin and range:

This next diagram shows what happens as the forces of weathering begin to work on the new landscape. The topmost parts of the layers that are sticking up begin to erode away (the mountains) and the eroded material accumulates in the lowest regions (the valleys):

The weathering of the high regions and the transport of the eroded material by the forces of wind and water into the lower regions continues:

The exposed top layers of the tilted blocks are eroded away until they are completely gone, exposing the layers below which are also eroded, eventually leaving only a flat plain atop tilted layers.

If the region should subside and become submerged then layers will begin accumulating atop them:

If the region is again uplifted and subjected to erosion and if a river flows through the region as it is uplifted then a canyon will be cut into the layers:

This is what happened at the Grand Canyon.

--Percy

Edited by Percy, : Fix quote.

Edited by Percy, : Typo.


This message is a reply to:
 Message 45 by Faith, posted 03-14-2015 12:45 PM Faith has not yet responded

Replies to this message:
 Message 89 by ThinAirDesigns, posted 03-15-2015 9:28 AM Percy has acknowledged this reply

  
Percy
Member
Posts: 20398
From: New Hampshire
Joined: 12-23-2000
Member Rating: 4.7


(1)
Message 90 of 1939 (752973)
03-15-2015 9:37 AM
Reply to: Message 48 by Faith
03-14-2015 12:52 PM


Faith writes:

Yes, but I didn't have the evidence of the order of things at the G.U. level, I didn't see how the layers would have butted up against it if deposited in the order usually accepted.

If by "butted up against it" do you mean the way your diagram shows new layers forming adjacent to the supergroup layers and butting up against them (Your diagram is mislabeled, by the way - what you've labeled the Great Unconformity is actually layers of the supergroup. The Great Unconformity is at the boundary at the very top of the supergroup layers. That boundary is at an angle to the supergroup layers themselves, and your diagram fails to show that, too.):

If this is what you mean, there is no evidence that anything like this ever happened. The Vishnu Schist adjacent to the supergroup layers were already there when the supergroup layers were deposited. When the stretching of the continent caused all the faulting that formed the blocks of basin and range then the lowest supergroup layers slipped to be adjacent to older Vishnu Schist layers. What we see in the region of the Grand Canyon you're looking at is just the very lowest and oldest layers of the supergroup.

See my previous Message 88 for a detailed illustration of how the layers at the Grand Canyon formed.

--Percy


This message is a reply to:
 Message 48 by Faith, posted 03-14-2015 12:52 PM Faith has responded

Replies to this message:
 Message 100 by Faith, posted 03-15-2015 3:58 PM Percy has acknowledged this reply

  
Percy
Member
Posts: 20398
From: New Hampshire
Joined: 12-23-2000
Member Rating: 4.7


Message 170 of 1939 (753271)
03-18-2015 5:33 PM
Reply to: Message 169 by Faith
03-18-2015 3:46 PM


Re: The Reformers on Science
Faith writes:

HOWEVER, this is all off topic in this thread.

But your final comment on the topic was just a couple days ago in Message 131:

I'm giving up on this thread at this point. I've concluded I didn't have the OP thought out and don't have the evidence I thought I had. Thanks.

So I didn't bother replying to your last message to me, and I didn't poke my nose in as moderator when the topic drifted because you, the thread's originator, had abandoned it.

But if your comment that the thread is now off-topic means you want to resume discussing the topic then I think only a statement of what you really meant to say in the OP is needed.

--Percy


This message is a reply to:
 Message 169 by Faith, posted 03-18-2015 3:46 PM Faith has responded

Replies to this message:
 Message 171 by Faith, posted 03-18-2015 5:36 PM Percy has acknowledged this reply

  
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