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Author Topic:   Depositional Models of Sea Transgressions/Regressions - Walther's Law
NoNukes
Inactive Member


Message 256 of 533 (726975)
05-14-2014 10:01 AM
Reply to: Message 252 by Faith
05-14-2014 9:03 AM


Re: "Parallel"
cross section are in fact much more neatly parallel overall
More neatly parallel?
What they prove is that tectonic disturbance did not occur during their laying down at all,
Interesting conclusion. We had an earthquake in Northern Virginia a couple of years ago. The seismic activity was felt at least as far south as Central North Carolina. But when I went outside I found that all of the streets that had been approximately horizontal remained so. Could not see any difference in alignment. The streets were all still nearly parallel to their original planes as far as I could see.
I'm not sure what kind of distortions from perfectly flat and horizontal you would accept as being evidence of tectonic activity, but when you call the layers in your drawing parallel, then I can see that you would ignore any deviation from horizontal anyway.
Edited by NoNukes, : No reason given.

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Percy
Member
Posts: 22388
From: New Hampshire
Joined: 12-23-2000
Member Rating: 5.2


(2)
Message 257 of 533 (726987)
05-14-2014 11:53 AM
Reply to: Message 252 by Faith
05-14-2014 9:03 AM


Re: "Parallel"
Hi Faith,
I don't have any problem with you using the term "parallel" when you're talking about something like this:
But you're going to confuse people about what you really mean if you use the term "parallel" when what you have in mind is this. You could describe the layers as roughly aligned with one another or as predominantly horizontal, but they're certainly not parallel:
You again have to realize how exaggerated are the tilts on diagrams like this where the tilted portions are circled in red:
Take, for example, the middle red circle which shows the layers tilting upward from the Vermilion Cliffs to the Grand Canyon, a distance of about 60 miles. Over that distance the elevation increases about 2000 feet to the canyon rim, or about 33 feet per mile. That's less than a 1% grade, 0.625% actually. That's a difference of only 0.36 degrees from the horizontal. If you were standing on a grade of 0.625% right now you'd think you were standing on level ground.
So what looks like a dramatic tilt and a dramatic increase in elevation on that diagram is actually almost flat level, and at any significant scale the boundaries between layers are going to appear horizontal and parallel, as you can see in this image of the Grand Canyon:
Now, getting back to the original point, we're trying to explain to you that the effects of tectonic forces were not completely absent from the region during the half billion years that these layers were deposited. If major tectonic forces that elevated the entire Grand Canyon region cause a grade of only 0.625%, then we should expect equally unspectacular grades for tectonic forces that occurred before all the layers were deposited and therefore only affected some of the layers.
And this is just what we find. We know that the thickness of the Temple Butte ranges from 0 ft in some parts of the Grand Canyon to a couple thousand feet in Nevada around 75 miles west. The angular difference between the top and bottom boundaries of the Temple Butte is therefore 0.5%, just slightly less than that for the tilt for the geography between the Vermilion Cliffs and the Grand Canyon.
Of course the top and bottom boundaries of the Temple Butte are unconformities and so erosion confuses the picture of how much of the effect was tectonic, but erosion alone combined with sea transgressions/regressions would be very unlikely to cause that great an angle.
--Percy
Edited by Percy, : Clarify.
Edited by Percy, : Found a Grand Canyon image I liked better.

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edge
Member (Idle past 1705 days)
Posts: 4696
From: Colorado, USA
Joined: 01-09-2002


Message 258 of 533 (727000)
05-14-2014 1:09 PM
Reply to: Message 243 by Faith
05-13-2014 8:53 PM


Re: Thickness of layers doesn't change parallel
I was never talking about parallel top and bottom of each layer, that's your own daydream.
Well, then, you shouldn't be looking at pictures of the canyon walls.
I was always talking about a whole block of parallel layers which my drawing illustrates just fine.
I'm not sure what you mean by a 'block of parallel layers' if you are ignoring the layers...

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edge
Member (Idle past 1705 days)
Posts: 4696
From: Colorado, USA
Joined: 01-09-2002


Message 259 of 533 (727001)
05-14-2014 1:10 PM
Reply to: Message 244 by Faith
05-13-2014 8:57 PM


Re: photobucket came through
Wow, what obfuscation!
Heh, heh...
When you don't show us the obfuscation that you are talking about, that's the greatest obfuscation of them all.

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edge
Member (Idle past 1705 days)
Posts: 4696
From: Colorado, USA
Joined: 01-09-2002


Message 260 of 533 (727002)
05-14-2014 1:13 PM
Reply to: Message 245 by Faith
05-13-2014 9:06 PM


Re: the great unconformity
I got the description from geology websites, I didn't make it up. It ought to be obvious that I said "root of a mountain range" not root of "an eroded package of rocks" as the usual interpretation I've encountered is that this tilted block of layers was the foundation of such a mountain range. I believe you might even find roxrkool saying so somewhere on this very forum.
In some cases, it was a mountain range and in some cases, not. I prefer the more general description to include all situations.
And I was not generalizing when I said it was eroded nearly flat, that too is a description of the one and only Great Unconformity as I've many times found it in Geology sources.
Flat in general and flat on a large scale, but in places there is relief on the surface. Some of these sections presented here even show that.

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edge
Member (Idle past 1705 days)
Posts: 4696
From: Colorado, USA
Joined: 01-09-2002


(1)
Message 261 of 533 (727003)
05-14-2014 1:25 PM
Reply to: Message 246 by Faith
05-13-2014 9:13 PM


Re: the great unconformity
What I would point out is that the whole area rose at that point, was lifted up. The pushing up of the pieces of strata plus the intrusion of magma are part of that scenario.
What about the intrusives and the sediments that were partly eroded previously?
if the strata buckled and then broke at this location, ...
Why would it buckle and break?
... it should have continued to the north and south of it unbroken, ...
Why north and south?
... though the diagram doesn't show anything at that level.
Oh...
You really don't understand how to interpret cross-sections, do you?
The rubble from the breaking and sliding ...
What is your evidence for breaking (brecciation) and sliding?
... could be quite some distance from this location too, ...
Why? What is the direction of the strain?
... or spread out along the distance, as well as part of the rock over which the strata above was uplifted, ...
What do you mean? What rock is being uplifted over what rock?
If the vergence of your deformation was vertical, why would the deformation form a (kind of) flat layer?
... and I still think much of it is what ended up as Vishnu schist,.
Then you need to explain the compositional differences and why the Vishnu is intruded by granite, but the overlying rocks are not.
Faith, your wording is vague and your logic is mushy; you have no evidence. I have asked you repeatedly for evidence of dislocation along the unconformity and you have done nothing but regurgitate this melange of disconnected ideas.

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edge
Member (Idle past 1705 days)
Posts: 4696
From: Colorado, USA
Joined: 01-09-2002


Message 262 of 533 (727004)
05-14-2014 1:28 PM
Reply to: Message 249 by Faith
05-13-2014 10:14 PM


Re: "Parallel"
Oohh, BR-U-U-U-U-U-U-THER.
Obviously the plan here is just to garble up EVERYTHING. Wow.
Plainly, the contacts are not parallel, and what do we look at in the canyon wall if not contacts?
Just like the contact between the 'fish' and the 'snake'...

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edge
Member (Idle past 1705 days)
Posts: 4696
From: Colorado, USA
Joined: 01-09-2002


(1)
Message 263 of 533 (727010)
05-14-2014 1:56 PM
Reply to: Message 252 by Faith
05-14-2014 9:03 AM


Re: "Parallel"
The actual strata illustrated on the GS-GC cross section are in fact much more neatly parallel overall than my drawings anyway, with nice tight contact lines and all the rest.
Of course, the section is on a scale of tens of kilometers per page whereas your little diagram is at centimeters per page.
This is a silly argument, Faith.
But even if they were as lumpy as my illustration they would illustrate the point I've been trying to make forever against the stubborn pedantic nitpickery of EvC.
Well, here is what MW-Online says...
Full Definition of PARALLEL
1a : extending in the same direction, everywhere equidistant, and not meeting
b : everywhere equally distant (bold added)
So, I assume you are using a different definition of 'parallel'?
What they prove is that tectonic disturbance did not occur during their laying down at all, ...
Well, I'd agree that it was not severe disturbance, however, there was plenty of action elsewhere in the region and on the continent. The Colorado Plateau happened to behave as a rigid block at this time, which we have demonstrated.
... but did in fact occur after they were all laid down from at least Tapeats to Claron and I think probably both higher and lower, ....
Not really. The Ancestral Rockies rose during this time and proved much of the sediments to the CP region. And realistically, there were several unconformities in the GC area attesting to this. Remember, the base of the Claron is an unconformity, probably related to the Laramide Orogeny, and the formatin itself is composed of lake sediments and coarse conglomerates shed from the east.
... at which time, at the end of what was no hundreds of millions of years, ...
You like making unsupported assertions, do you not?
something pretty drastic happened to shake up the land.
Not really. It was another uplift with very little deformation. All of the action was at the Hurrican Fault and several other minor faults in the region.
You can see this in the rise and fall of the surfaces of the land, the "contour" of the land as I've often referred to it, as well as in the tremendous erosion that broke off chunks of strata leaving the cliffs and canyons of the Grand Staircase.
This is an erosional event, not really tectonic, other than the fact that the region was uplifted, largely as a block.
This erosion also scoured the surface of the Kaibab plateau and broke open the Grand Canyon while the extra mile of sediments above the Kaibab was still there.
Actually, I think that that post Kaibab rocks were eroded earlier, at least in part, when the river meanders were established.
But I'm glad you agree that this was largely erosional due to uplift of the region.
The upheaval was accompanied by volcanic activity beneath both the GC and the GS, and earthquakes at fault lines which caused the angular conformity at the far north of the GS ...
Please reference this unconformity.
... and the displaced strata at other points, ...
What strata at what other points?
As far as I know the faults were late, but some were likely pre-Claron in part.
All that occurred after all the strata were stacked, which is evidenced by their parallel form which follows the rising and falling of the land.
But maybe not all of the strata and there is certainly evidence of unconformities in the section.
The main problem here is that you ignore the evidence for at least three deformational events and at least two erosional event prior to the Great Unconformity.
I think it is plain perverse of anyone to pretend not to see this or deny it once they've seen it.
I'm sure you are correct. I mean, certainly, you have amassed a fortress of evidence and support for your arguments.
Edited by edge, : No reason given.

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Percy
Member
Posts: 22388
From: New Hampshire
Joined: 12-23-2000
Member Rating: 5.2


Message 264 of 533 (727016)
05-14-2014 4:36 PM
Reply to: Message 246 by Faith
05-13-2014 9:13 PM


Re: the great unconformity
Hi Faith,
Here's what's wrong with your idea about the origin of the Great Unconformity. You're saying we start with this, where the sky blue layer is the top layer of the supergroup:
And we all agree that this is what we see today at the Grand Canyon where the tilted layers of the supergroup stop at the bottom of the Tapeats, which is the yellow layer in this diagram:
So where did all the material in the first diagram go that is missing in the second? Take, for example, the bottommost layer that is a darkish orange. In the first diagram it stretches from one side of the diagram to the other. In the second diagram it is clipped short at the Tapeats and then below and to the right at the Vishnu Schist. It used to stretch for hundreds of miles in all directions buried beneath a mile of rock, now it's just a short stretch of maybe a mile. Where did all the cubic miles of rock go? That much rock could not help but leave huge amounts of evidence behind telling us what happened to it.
--Percy

This message is a reply to:
 Message 246 by Faith, posted 05-13-2014 9:13 PM Faith has replied

Replies to this message:
 Message 265 by edge, posted 05-14-2014 6:25 PM Percy has replied
 Message 271 by Faith, posted 05-15-2014 3:13 AM Percy has replied

  
edge
Member (Idle past 1705 days)
Posts: 4696
From: Colorado, USA
Joined: 01-09-2002


Message 265 of 533 (727019)
05-14-2014 6:25 PM
Reply to: Message 264 by Percy
05-14-2014 4:36 PM


Re: the great unconformity
Take, for example, the bottommost layer that is a darkish orange. In the first diagram it stretches from one side of the diagram to the other. In the second diagram it is clipped short at the Tapeats and then below and to the right at the Vishnu Schist.
Actually, I would place the Vishnu under and to the left of the lowest GC Supergroup unit.
In a pure geological sense, the Vishnu cannot cut supergroup rocks. Those rocks would extend to a point where they would be a) cut off by a fault, b) be eroded away as another limb of a fold, or c) never deposited.
Your point is taken, however, that Faith's scenario results in 'room' problems.

This message is a reply to:
 Message 264 by Percy, posted 05-14-2014 4:36 PM Percy has replied

Replies to this message:
 Message 267 by Percy, posted 05-14-2014 8:33 PM edge has replied

  
Faith 
Suspended Member (Idle past 1444 days)
Posts: 35298
From: Nevada, USA
Joined: 10-06-2001


Message 266 of 533 (727020)
05-14-2014 6:32 PM


Unbelievable.
Edited by Faith, : No reason given.

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Percy
Member
Posts: 22388
From: New Hampshire
Joined: 12-23-2000
Member Rating: 5.2


Message 267 of 533 (727028)
05-14-2014 8:33 PM
Reply to: Message 265 by edge
05-14-2014 6:25 PM


Re: the great unconformity
edge writes:
In a pure geological sense, the Vishnu cannot cut supergroup rocks. Those rocks would extend to a point where they would be a) cut off by a fault, b) be eroded away as another limb of a fold, or c) never deposited.
When I said "clipped" I was describing the image, not geological actions. I wanted to make sure Faith was aware how much the extent of the supergroup layers had been truncated in the second image versus the first, and how much of the supergroup layers had simply disappeared.
There was no effort to accurately represent the schist as it didn't seem a relevant factor.
--Percy

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edge
Member (Idle past 1705 days)
Posts: 4696
From: Colorado, USA
Joined: 01-09-2002


Message 268 of 533 (727029)
05-14-2014 8:41 PM
Reply to: Message 267 by Percy
05-14-2014 8:33 PM


Re: the great unconformity
When I said "clipped" I was describing the image, not geological actions. I wanted to make sure Faith was aware how much the extent of the supergroup layers had been truncated in the second image versus the first, and how much of the supergroup layers had simply disappeared.
There was no effort to accurately represent the schist as it didn't seem a relevant factor.
Well, the fact is that those units are truncated at the Great Unconformity. Faith does not recognize this fact. As I understand it, she want's it to be a tectonic contact for which there is no evidence. The GC Supergroup is tilted and truncated.

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 Message 267 by Percy, posted 05-14-2014 8:33 PM Percy has seen this message but not replied

Replies to this message:
 Message 272 by Faith, posted 05-15-2014 3:20 AM edge has replied

  
edge
Member (Idle past 1705 days)
Posts: 4696
From: Colorado, USA
Joined: 01-09-2002


Message 269 of 533 (727030)
05-14-2014 8:46 PM
Reply to: Message 266 by Faith
05-14-2014 6:32 PM


Unbelievable.
Thank you.

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edge
Member (Idle past 1705 days)
Posts: 4696
From: Colorado, USA
Joined: 01-09-2002


(1)
Message 270 of 533 (727040)
05-15-2014 1:17 AM


More unbelievable stuff!
With a tip of the hat to Tim H over at Carm, here is one of the best articles on Joggins polystrate trees that I've ever read. The reason for posting it is Figure 7, which I'm sure Faith will find laughably incredible since it shows 14 minor transgressive/regressive cycles in 2500 feet of section at the Joggins coal fields of Nova Scotia.
View of The Pennsylvanian Joggins Formation of Nova Scotia: sedimentological log and stratigraphic framework of the historic fossil cliffs | Atlantic Geoscience
I mean, it's really just an interpretation, right?

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