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Faith  Suspended Member (Idle past 1475 days) Posts: 35298 From: Nevada, USA Joined: |
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Author | Topic: Motley Flood Thread (formerly Historical Science Mystification of Public) | |||||||||||||||||||||||||||||||||||||||||||
Minnemooseus Member Posts: 3945 From: Duluth, Minnesota, U.S. (West end of Lake Superior) Joined: Member Rating: 10.0 |
But the fact remains that you've got a huge flat slab of rock covering a huge area where you thnk there used to be an ancient landscape with ancient forms of living things, and that is impossible. Your "huge flat slab of rock covering a huge area" was deposited as sediments (or perhaps volcanics). At time of deposition it was the top of the then stratigaphy ("geologic column") at its various locations. Be it on dry land or underwater, its top surface was the "landscape" of the time. There may or may not have been things living at that surface in the various locations.
edge writes: This is why we recognize both lithostratigraphy and chronostratigraphy in geology. Remember out favorite "Walther's Law" diagram:
The bottom left of this diagram illustrates the difference between lithostratigraphy and chronostratigraphy. As you go right to left, the lithostratigraphy (say, the sand unit) becomes progressively younger. And the top surface of the various sediments are the "landscape" of the time. Moose Edited by Minnemooseus, : Change subtitle.
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Minnemooseus Member Posts: 3945 From: Duluth, Minnesota, U.S. (West end of Lake Superior) Joined: Member Rating: 10.0
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I was interested in the use of the calcium content of the garnets found in the Vishnu Schist to determine the height of the rock above it that had provided the pressure to form the scshist and the garnets, which they determined to have been six miles. Of course they were thinking of the supposed former mountains they imagine to have existed there before the canyon. Metamophic petrology (what they are and how the rocks form) is some pretty heavy complicated stuff. It's been 40+ years since my met-pet class, and I wasn't that strong at it even then.
Garnets come in a lot of chemical varieties, depending on the bulk composition of the rock they grow in and other factors. There are end member varieties of garnets and there is also what is called "solid solution" in garnets - Garnets with compositions between the end members. Anyway, without getting into the really gory details, laboratory experiments can be done to determine the pressures and temperatures required for a certain composition metamorphic mineral to form. Apparently their variety of garnets required the pressure of 6 miles of burial.
The weight of the Paleozoic strata into which the canyon was cut has always been my explanation for the schist and the granite formed beneath the Great Unconformity, but that only comes to three miles, possibly four, not six. You know of course that I'm not giving that up in any case but it was interesting how they use the garnets. The thing is, you can't go from a high grade metamorphic rock to a low grade or unmetamorphosed rock at a contact unless that contact is either a nonconformity (like at the Grand Canyon) or a fault. What you would find is that the rocks under the greatest pressures and temperatures would be the highest grade metamorphics, and as the pressure and/or temperature decreases, the metamorphic grade of the rocks would correspondingly decrease. My analogy for your scenario would be having two pans of cake dough in the same oven. One gets baked to a near cinder and the other remains totally unbaked. Not going to happen. Which is why it's thought that a lot of rock had to be eroded off above the schist prior to the non-metamorphosed sediments being deposited. Moose Edited by Minnemooseus, : Fixed a blotch spelling.
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Minnemooseus Member Posts: 3945 From: Duluth, Minnesota, U.S. (West end of Lake Superior) Joined: Member Rating: 10.0 |
I got the general idea of the point you were making but wasn't able to follow the chain of logic. I mean that I think I understood the technical points, but not how they fit together into an argument. Here's my attempt at putting the pieces together: You first explain that the particular qualities of the garnets at the top of the Vishnu Schist required an overburden of about 6 miles in order to form. It was the video that claimed that "particular qualities of the garnets at the top of the Vishnu Schist required an overburden of about 6 miles in order to form". I really don't know the details of their reasoning, but I do know that the temperatures and pressures required for various metamorphic minerals to form can be determined through laboratory experiments.
Then you quote Faith insisting that there were only three miles above the schist. I have no idea where Faith comes up with that three mile figure. But she wants it to be the Grand Canyon Supergroup and younger currently present sedimentary rocks.
You rebut this position by saying that there cannot be high grade metamorphic rock on one side of a contact and low grade metamorphic or unmetamorphosed rock on the other side unless that contact is a nonconformity or a fault. Indeed. The rocks currently in contact with the Vishnu Schist were not there to be part of the metamorphism.
In context that would seem to be a reference to the Vishnu Schist//Tapeats contact, and your rebuttal then becomes an argument that this contact really is a nonconformity, and that deposition of the Tapeats must have taken place after the Vishnu Schist had already metamorphosed and cooled, else the Tapeats would itself have been metamorphosed though lower grade. Any rock at the same depth as the Vishnu Schist at the time of metamorphism would also have been highly metamorphosed. Back at the time of metamorphism, long before the Grand Canyon Supergroup and even longer before the Tapeats, there was supposedly (per the video) about six miles of rock above what is now left of the Vishnu Schist. That six miles, including a portion of the Vishnu, was eroded away prior to the Supergroup deposition. Were we able to see the nature of that long lost rock column, we would have seen progressively lesser grade metamorphism as we went up section. Metamorphism is not an on/off thing. You get lessening metamorphism as the pressure and/or temperature conditions decrease. Here's the analogy of how I see petrology (the study of rocks and their formation processes}: Sedimentary rocks are drinking milk. Igneous rocks are getting into drinking coffee of various strengths. Metamorphic rocks are getting into doing some heavy psychedelics. Or something like that. Moose
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Minnemooseus Member Posts: 3945 From: Duluth, Minnesota, U.S. (West end of Lake Superior) Joined: Member Rating: 10.0
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Tilting is not deformation. Deformation is bending, folding, stretching, compression or faulting. Both tilting and deformation can be present (as seems to be the case in the diagram but that you probably can't see), but they are not synonyms. Maybe Edge or Moose can be more definitive. Tilting is deformation. In a local outcrop it may be viewed as a low intensity deformation, but in the bigger picture, tilting is going to be an aspect of folding and/or faulting. Or can you come up with a scenario where a rock unit can be tilted without folding and/or faulting being involved? Moose
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Minnemooseus Member Posts: 3945 From: Duluth, Minnesota, U.S. (West end of Lake Superior) Joined: Member Rating: 10.0
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NoNukes writes: Percy writes: You're confusing reporters and journalists with scientists, and mystification exists only in your own mind. I think the issue is more fundamental than that. A physicist would not start every inquiry by proving that F = ma, and he would not question the origin of the sun every time he counted the number of sunspots on them. Similarly, a scientist studying the Jurrasic period is not going to write a bunch of papers proving that the earth is old or proving that dating methods work. That groud was well covered decades ago. If a popular science book is written describing the same period, the authors are not going to cover that material either. They do assume that the earth is old, for reasons that were covered when they were in college in countless fields of scientific endeavor. Etc. I gave the message a "Post of the Month". Via a new message elsewhere (hat tip to AZPaul3) I just rediscovered a relevant PZ Myers posting :
Writing synopses of science articles is hard quote: Etc. Moose Edited by Minnemooseus, : Added some quote from the message this is a reply to.
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Minnemooseus Member Posts: 3945 From: Duluth, Minnesota, U.S. (West end of Lake Superior) Joined: Member Rating: 10.0 |
The layer becomes skinny at that point not because of deformation but because it was deposited that way. I would be cautious about betting on such, even in the case of the above photo. eg: Boudinage quote: I think that this is a much more metamorphic situation than the first photo, but is it really that different? Moose
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Minnemooseus Member Posts: 3945 From: Duluth, Minnesota, U.S. (West end of Lake Superior) Joined: Member Rating: 10.0 |
minnemooseus writes: Remember out favorite "Walther's Law" diagram:
The bottom left of this diagram illustrates the difference between lithostratigraphy and chronostratigraphy. As you go right to left, the lithostratigraphy (say, the sand unit) becomes progressively younger. And the top surface of the various sediments are the "landscape" of the time. It would probably also be useful to explicitly point out to Faith that by "landscape" you mean seascapes being created according to the principles of Walther's Law. These seascapes that become preserved in the stratigraphic record are not the landscapes that the sea transgressed across. Those landscapes are gone, ground away by active coastal waters into sand, silt, mud and clay. The constituent elements of the landscape are preserved as particles of sediment. For example, if the landscape was rich in some element like iron, then the marine sedimentary layers will include that element. I interpret "landscape" to be the sums of all the "solid surfaces" of a given time. By "solid surfaces", I mean the top of geologic materials, below the atmosphere or whatever body of water. Topography and Bathymetry. Topography - Wikipedia
quote: Bathymetry - Wikipedia
quote: Now, per your "created according to the principles of Walther's Law". I still resist invoking Walther's Law as being a process. Recently I discovered a better terminology:
https://en.wikipedia.org/wiki/Deposition_(geology)#Null-point_hypothesis quote: quote: Now, Faith's muddled scenario apparently involves sediment being eroded off the continents and being deposited at ocean shorelines. While I envision that the results of the Faith variation of the mainstream concept would look substantially different from the above graphic, I think that Walther's Law would still be valid. It's still a migrating environment. Faith also invokes large sediment amounts being stirred up in the ocean basins and somehow being washed up into the near shore environment. While there are all sorts of problems with this scenario, I visualize that such might result in a sediment size distribution that goes from coarse to fine from seaward to landward (the opposite order of the "Walther's Law" model). I see this because of the sediment deposition fining as you get further from the ocean basin sediment source. So, the final stratigraphy might be some sort of hybrid of the land sourced sediment model and the ocean basin sourced sediment model. I would expect that even such hybrid would still result in a Walther's Law relationship. Now about a bit of Percy statement from message 556:
Percy, message 556, writes: The ocean floor has not dropped. Surveys of the ocean floor after WWII in order to aid submarine navigation revealed a great deal of information about mid-oceanic ridges and sea floor striping and so on, but not an ounce of evidence for dropping sea floors. As I understand it, the great sea transgressions and regressions in geologic history were indeed largely caused by ocean floor rises and falls. This is the reality that ties into the "catastrophic plate tectonics" fantasy. Over the years I've tried and failed to find good (or even mediocre) internet literature on this process. Perhaps to be discussed further in later messages. Moose Edited by Minnemooseus, : Failure of proofreading.
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Minnemooseus Member Posts: 3945 From: Duluth, Minnesota, U.S. (West end of Lake Superior) Joined: Member Rating: 10.0 |
There is no evidence left of the perfection of the original Creation, I'm assuming it. What I actually see is wreckage, period. And the strata certainly are evidence of the Flood. It has struck me that the Biblical narrative makes to mention of the flood affecting anything other than drowning all the air breathers except those on the ark. After submerging the land areas for about a year, the waters receded and everything was again ready for the ark survivors. No consideration of the devastation that would have happened to all plant life, among other things. Even if the extreme remodeling of the lands as Faith envisions had not happened, the land surfaces would still be unsuitable for sustaining the ark survivors. Moose
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