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Author | Topic: TEMPORARY: So how did the GC (Geological Column) get laid down from a mainstream POV? | ||||||||||||||||||||||||||||
Tranquility Base Inactive Member |
This is a continuation of the original 'So how did the GC . . . ' thread that presumably Percy will attach to the end of the old thread once it is fully working again.
Wehappyfew, I agree that Lyellian features are superimposed on the epeiric sea beds (ie the beds deposited as seas 'transgressed' and 'regressed' onto much of the area of the continents). I take your points on continental shelves being flat. I'm aware of El Capitan etc but I still think the vast majority of, eg the marine Grand Canyon area beds, appear to be, perhaps not too flat (although I would love to see cross sections compared of modern vs epeiric), but too undisturbed. One can follow the flat interfaces with only very little ups and downs. Much of these beds do not look like marine habitats as supported by the mainstream comment I cited. Even the marine burrowing looks more like escape burrows becasue the sediments are not mixed throughout the regions near the burrows indicating that these burrows were created suddenly in new sediments and then it ceased (we know why). Both of our arguements are at extremes and the data seems to be just compatible with both IMO although of course I beleive you are stretching it and you believe I am stretching it! [This message has been edited by Tranquility Base, 05-27-2002]
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Tranquility Base Inactive Member |
I have now found mainstream sources which state categorically that much of the sediments on the continents were generated by epeiric seas (transgressions of sea onto land). We all of course knew this was true becasue how else do vast marine beds form on land!
My sources at this point are citaitons from lecture notes on the web from mainstream geology courses. I will ultimately find peer reviewed sources on this but here are the excertps, and web sites of, from some mainstream geology courses on origin of the geological column:
quote: The first lecturer goes on to point out that these layers were generated gradually of course but my point here is simply that 'much' of the Cambrian to Cretaceous was formed by depositons from these seas not as river deltas etc although I agree that there are Lyellian features superimposed on these beds. In any case it is clear that the majority of layering from Cambrian to Cretateous in North America at least is due to transgressions and regressions of the sea. And as I said, we all knew this although I find that mainstream geolgoists and textbooks emphasize the smaller Lyellian features on some occassions completely neglecting to mention the major role played by the epeiric seas. Most continental formations are marine so it is no surprise. I will state it as such: much of the continental geological column was laid down by epeiric seas. The key word that might be new for some is 'much'. [This message has been edited by Tranquility Base, 05-27-2002]
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Tranquility Base Inactive Member |
Joe, you were wondering about my conceptions/misconceptions about sea-floor spreading etc. Yes, thanks. I now understand that the sea-floor spreading didn't fold the sea floor necessarily (or at all) but rather it is the build up of new sea floor ridges themselves that caused the sea level rises.
My thought that you also commented on that I called 'delayed subduction' was just me trying to work out what caused the regressions. I'm now aware that mountain building on continents could lead to sea level drops. Having said that, now that I've seen the graphs of actaul sea-level vs time over the last 500 million years (see Hamblin, Christiansen & Hamblin for example) I am really wondering whether the idea of 'delayed' subduction is not a bad one (and might be a mainstream one). The graphs vs time (extracted from the geological record) show gradually increasing sea levels (transgression) with a rapid initial gradient that then decreases and levels of. Then the sea-level suddenly drops (regression). The graphs actually look exactly like a charging/discharging capcitor (for those into electronics [This message has been edited by Tranquility Base, 05-27-2002]
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Joe Meert Member (Idle past 5680 days) Posts: 913 From: Gainesville Joined: |
quote: JM: So does glaciation.
quote: JM: you mean 1st order sea level curves.
quote: JM: Again, I am not sure why you would call it 'delayed subduction' since oceanic crust (all other things being equal) will subduct when it becomes negatively buoyant. In one sense, subduction is ALWAYS delayed until such time as it becomes subductable. I must admit that I am not sure what your point is here at all!
quote: JM: Sea level fluctuations are not all that simple. As I said, there are many orders of sea level fluctuations and they are due to different effects (glaciation, orogeny, seafloor spreading, the geoid, subduction) and to try and simplistically attribute them all to a single cause is dangerous (if not totally wrong). By the way, I would call your idea a hypothesis (it's not quite to the level of theory yet).
quote: JM: Then you've not looked very far. try searching glaciations and sea level. Try searching geoid and sea-level. Have a look at hereCheers Joe Meert
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Tranquility Base Inactive Member |
Yes, Joe I'm mainly talking the 1st order curves. I'm not denying that there will be local effects and smaller global effects superimposed on this. But like any dynamical model it will have a central mechanism and my hypothesis is this idea of delayed subduction.
It's probably complete garbage but it might even be part of the mainstream thinking - I'm just thinking aloud. I just did a search on the web and even came up with one hit to 'delayed subducton' and am currently evaluating its relevance. I agree I'm moving into new teritory here for me but physicists have a history of that of course! I don't deny that all things being equal the oceanic plates will dive under due to their density but one could imagine that density aside there will be frictional issues and that the relatively rapid sea-level drops could be due to a frictional theshold that gets periodically overwhelmed (cf earthquakes). PS 1 - I can't access your link.PS 2 - I take your point about 'delayed'. I'm using it because the subduction is delayed relative to the spreading and sea level rise. From the normal point of view I agree it's more like 'forced subduction'. The 'delay' comes from the (do I really need to say hypothetical?) frictional threshold. [This message has been edited by Tranquility Base, 05-28-2002]
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edge Member (Idle past 1707 days) Posts: 4696 From: Colorado, USA Joined: |
quote: I'm not sure with whom you are disagreeing here. Other than the fact that, as far as I know, 'Lyellian' does not necessarily exclude deposition in shallow continental seas. I also think you need to clear up the 'continental' and 'marine' definitions. [This message has been edited by edge, 05-28-2002]
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Tranquility Base Inactive Member |
Thanks Edge, I was actually feeling that too (Lyellian vs epieric seas). I can appreciate that
(i) I'm not saying anything controversial(ii) except that I need a better word than Lyellian Perhaps I simply mean that the geological column can be considered to have been generated by a series of epeiric sea transgressions/regressions followed by primarily non-marine erosional processes that generated the smaller component of sediments. From the non-mainstream POV we would say that the flood surges generated the continental epeiric sea layers (which is much of the geological column). Each regression was followed by erosion of these soft layers via fresh water. At the end of the flood we have the final regression generating, eg Grand Canyon etc, out of soft layers, and then 4500 years of Lyellian gradualism. That is my current view of it but I would prefer it didn't side track us from the mainstream view in this thread. Debate it with me in the 'rapid layers' thread if you want. Is there something wrong with talking about marine strata on continents? Is there a better way to put it? Wait - I said that 'most continetal formations are marine'. I was hoping that that was not ambiguous - I meant: most formations on continents are actually marine. Is there a better way to say this? [This message has been edited by Tranquility Base, 05-28-2002]
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edge Member (Idle past 1707 days) Posts: 4696 From: Colorado, USA Joined: |
quote: The flood conotation is deceptive. If we are to accept that, any continental areas covered by water are in a state of flood. This would include the present.
quote: Rather a gross simplification. We know that some layers were no longer soft sediments.
quote: Nope, impossible. The Grand Canyon was carved in lithified sediments. If not, then we are wasting a lot of time and money protecting workers in trenches and tunnels and such. Heck, if soft sediments can support thousands of feet of canyon walls, we shouldn't need to worry about ground support at all in mines and quarries.
quote: I understand what you mean, but your wording 'marine-continental' deposits is a bit ambiguous. Marine sediments are deposited in the sea ... that would include shallow epeiric seas that cover parts of a continent. Marine deposits overlying continental crust could be called just that. I have heard them called 'shelf deposits' or 'shelf seas,' but perhaps there is a sedimentologist here who has a better handle on such terminology. They would be represented by the continental shelf and shallow seas such as the Baltic. Marine deposits would also include the pelagites and turbidites of the abyssal plains. Non-marine would be sediments deposited generally above sea level, including glacial, eolian, fluvial lacustrine deposits and others. While these are more subject to local deposition and subsequent erosion, there are substantially large deposits in some instances. Transitional environments would be deltas, tidal marshes and coral reefs.
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wehappyfew Inactive Member |
quote: A creationist with a sense of humor... that alone makes this discussion worthwhile.
quote: I'm not sure this is a reasonable interpretation of the "mainstream POV"... A continental landmass could spend quite a lot of time above sea-level... maybe even 99.9% of its history... and little or no net deposition might result. Then a brief submergence, coupled with a nearby orogenic pulse, might result in a thick sequence of shallow marine sediment grading laterally into delta and fluvial deposits nearer the source of clastics. Over-broad generalizations sans evidence are usually very wrong. Similar problems arise from your other forays into unfamilar territory...
quote: You THINK you know why...Please consider a small portion of the "mainstream POV" you are, perhaps, unfamilar with... Most net deposition in almost all sedimetary sequences - modern and ancient - occurs during the highest energy events. So storms commonly plane off the underlying sediment, mix it up, and redeposit it in a graded bed. This sequence is ubiquitous in the GC and in modern sediments. Any organisms that survive the tempest will probably have to burrow their way to the new surface through the freshly deposited sediment, where they will happily create new homes in the top layer. This layer is most likely destined to be sheared off by the next storm, so it is under-represented in the GC. Just to set the record straight, I fully agree that a large proportion of the GC on continents is epeiric in nature. This follows unavoidably from the bias towards preservation of marine sediments I mentioned in the first paragraph. Extrapolating a Noah's Flood from this fact is possible only by ignoring, or being ignorant of, a vast wealth of geologic knowledge built up over the last 200 years. Bringing you up to speed on the whole shebang is cumbersome and difficult in a BB format, but with the pleasant tone displayed by you so far, you can expect as much assistance as possible from me.
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Tranquility Base Inactive Member |
Edge, my main point is that much of the geological column was laid down as marine beds on land. We would be silly not to point this out as subscibers to flood geology and take some heart from it!
Three comments on your point about the Grand Canyon etc being cut out from lithified sediments:(i) We presume this was one of the later episodes of the 400 day event. (ii) Mt St Helens displays sharp canyons cut out of soft layers (and yes there are of course scale differences here). (iii) It's possible that a lot of the canyon collapsed due to it being soft and that 4500 years of Lyellian processes has worn down the collapsed edges through both erosion and landslides. [This message has been edited by Tranquility Base, 05-29-2002]
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Tranquility Base Inactive Member |
Wehappy, thanks for your offers of help. I'll accept it gladly. At the same time don't write me of too quickly either!
From the first order sea level curves it does seem to me that the continents have spent a lot of time underwater. Having said that the main piont for me is that most of the geological column on land is marine regardless of how long it took. If anything we would totally agree with you on the orogenic pulses - that much of the geological column tells a story of uninterputed deposition for thousands of vertical feet at a time (you would probably not say 1000s of feet I suspect I'll agree that your scenario for recording only the undisturbed sediments rather than than the actual sea floors is possible. But when the raw data tells the story of continuous parallel layering Occam's razor's first port of call is surely that the layering was continuous and rapid due to the lack of evidence of long-term habitation. Your scenaruio is possible but the dat better fits a sinlge 'storm' than many (1000s? of) storms. PS - I've read quite a lot on the early geolgoists. It is fascinating stuff and I'm not just in it for the flood geolgoy. I like the science of it too. I'm a fan of Hutton, Smith, Lyell, Cuvier, Mantell and Buckland etc. I have my own ideas of why the 'creationist' geologists failed to see the flood in the strata. The main reason IMO was that no-one expected that you could get layering from rapid deposition - they all thought it only happened due to cyclical seasonal events. The majority at least hadn't thought much about hydrodynamic sorting as a mechanism for rapid layering. The other aspect is that no-one knew about continental drift, the sea-level cycles and the possibility of tectonically induced flood surges. This is all a part of modern flood geology and IMO it is a valid sceanrio. [This message has been edited by Tranquility Base, 05-29-2002]
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Joe Meert Member (Idle past 5680 days) Posts: 913 From: Gainesville Joined: |
quote: JM: Well, then I suggest you look again. Try reading some of Agassiz's material. I am still swamped with other work, but I will say that this whole discussion reminds me of words i read most recently in Pennock's "Tower of Babel". Namely that flood geology makes sense as long as the details are ignored. Now, I know that's not fair to say without providing those details, but neither have you (or your side) provided details to support the Noachian flood. I will get back to this, but June 1 is a big deadline here. Cheers Joe Meert
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Philip Member (Idle past 4723 days) Posts: 656 From: Albertville, AL, USA Joined: |
I hope that TB will at some time recap his main points concerning his GC scheme in layman's terms so that I may ingest it better.
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edge Member (Idle past 1707 days) Posts: 4696 From: Colorado, USA Joined: |
quote: Of course you take heart from it. The problem is that this ignores all of the rest of the geological data.
quote: Usually, sediments would be very weak 400 days after deposition. And you did say they were soft. That means weak. That means they cannot support steep walls, but will flow.
quote: This would be a silly comparison, but we hear it all the time. If the MSH valleys were thousand of feet deep, the walls would not stand.
quote: Are you admitting that carving the GC took longer than the standard creationist line? I suppose that by some miracle the rocks of the GC suddenly lithified and the rate of erosion decreased just before it was observed by humans. This is sort of like the speed of light decreasing until the 1960's when we first obtained the ability to make accurate measurements.
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edge Member (Idle past 1707 days) Posts: 4696 From: Colorado, USA Joined: |
quote: I remain uncertain as to what your point is. Why do you keep repeating this point? Is there some controversy?
quote: You have never provided any evidence for this. Why do you think that continuous parallel layering is diagnostic of flood deposits?
[QUOTE]PS - I've read quite a lot on the early geolgoists. It is fascinating stuff and I'm not just in it for the flood geolgoy. I like the science of it too. I'm a fan of Hutton, Smith, Lyell, Cuvier, Mantell and Buckland etc. I have my own ideas of why the 'creationist' geologists failed to see the flood in the strata. The main reason IMO was that no-one expected that you could get layering from rapid deposition - they all thought it only happened due to cyclical seasonal events. I'm not sure who you are talking about here. Who has said that you cannot get layering in storm deposits or rapid deposition? If you are talking about early geologists, I am sorry, but they are not here. You are stuck with us. Why is it that creationists like to pick on the dead guys?
quote: I'm not sure that there was a reason to. However, why don't you address what we say about it?
quote: You mean marine transgressions and regressions? No they didn't know about that in the early days of geology. So what? We do now, and it is a part of mainstream geological theory. You have made it a part of your scenario to give it an air of reality, but you are required to ignore major tracts of geological evidence. You are very adept at making sweeping assertions about the geological column and sedimentation, but are seriously short on evidence. Could you please provide some evidence that supports your scenario at the exclusion of mainstream science?
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