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Author Topic:   Geology- working up from basic principles.
stewartreeve
Junior Member (Idle past 5190 days)
Posts: 10
From: Central Coast, NSW, Australia
Joined: 01-06-2010


Message 121 of 156 (542194)
01-08-2010 8:49 AM
Reply to: Message 118 by Dr Adequate
01-07-2010 10:30 AM


OK, firstly, someone asked, "Are you a geologist"? No, i'm not; i hope i don't seem like i am pretending to be. I'd call myself a geology enthusiast as the very best. No, my primary interests WRT geology are, at this point, the philosophical/logical aspects (stemming from my more frequent interest in the Philosophy of Science, it's Logic, etc...)
Secondly, i can't respond to all this - i either don't know enough of what is being said, or i just don't have time to (more the latter, but definitely some of the former)...but i'll do my best.
But do me a favour: don't just disagree with me because i am suggesting a divergent perspective (i'm not saying that people necessarily are doing that, i'm just asking that it doesn't happen ) - there are things i don't understand well and will seek to have clarified by people that know more than me - and i may also request further breakdown on assertions, etc; but there are also things i do understand well, such as arguement/logic structure, and even particle-chemical interactions.
Now that i've had my cry (), back to it...
A "Law" can't be a "law" if it has exceptions; that's why the Principle of Superposition is only a Principle (which is great!) but perhaps no longer even deserves such a title, given that flowing slurries (a very common phenomena!) can produce the same basic features simultaneously.
What it does not, apparently, provide, is a mechanism whereby thing on the bottom can settle after the things on the top.
You're right, it doesn't provide such a mechanism, and i think i would be at fault to suggest that it does (so i don't).
And that's not the perspective by which i'm suggesting that the Principle of Superposition has some issues in light of a dynamic mechanism, which hypothetically forms successive strata....i'll express it in terms of something else i read recently (tell me if i'm on the money, or getting ideas mixed up...)
Doesn't the Principle of Superposition have the following corollary/necessary implication (paraphrased):
"For any given vertical coordinate in a layer, it follows that any given horizontal point is said to be deposited at the same time, and thus, has the same age" (yes? no? am i mixed up with the Principle of Original Horizontality? Don't think so, but i should ask...)
Consequently, the dynamic simultaneous deposition of layers potentially contradicts at least THIS interpretation/version of the Principle of Superposition, because it is possible to have the VERTICAL points being deposited at the same time (and thus having the same "age"), instead of the horizontal points being deposited at the same time, and thus having the same age....and this is just because the layers have been formed horizontally instead of vertically. It's a 90 degree axis shift, so to speak....
Logically speaking, what was considered a closed deduction now has another possible option, such that further deduction to a non-impossible conclusion must again close-off the other possibility (even if it is by a priori denial of the other possibility's validity - a valid proposition, but not a very good qulity one...)
At least that is one perspective on how dynamic formation of strata could affect an axiom like Superposition...i am tired....it's 12:45am now
It sounds to me as though you're talking about turbidite formation or something very similar. It would be a bit of a stretch to say that this contradicts superposition.
yeah, from what i know if turbidites (which is not admittedly not grand, though i understand slurry flow fairly well...) i can't see why what i'm saying would not apply to turbidites.
Hopefully the clay-settling notion (of being slow) is also not a "Principle" (though i do hear that A LOT!), as isn't even the norm...i still scratch my head at why geos keep saying it's so....
I believe that observation of actual geological processes has a lot to do with it.
I've actually heard quite the opposite from geos: that flocculation is the norm, and that dispersed particle settling (true Stokian - the "ideal"?) is actually the exception. Again, it is a matter of what conditions one hypothetically invokes, and many natural conditions cause particle agglomeration (yes, yes, i will get onto a brief theory and mechanisms of particle agglomeration later, as i have been requested to do...)
Edited by stewartreeve, : No reason given.

This message is a reply to:
 Message 118 by Dr Adequate, posted 01-07-2010 10:30 AM Dr Adequate has replied

Replies to this message:
 Message 124 by PaulK, posted 01-08-2010 9:32 AM stewartreeve has replied
 Message 134 by Dr Adequate, posted 01-11-2010 8:48 AM stewartreeve has not replied

  
stewartreeve
Junior Member (Idle past 5190 days)
Posts: 10
From: Central Coast, NSW, Australia
Joined: 01-06-2010


Message 122 of 156 (542195)
01-08-2010 9:06 AM
Reply to: Message 117 by edge
01-06-2010 11:10 PM


... that's why the Principle of Superposition is only a Principle (which is great!) but perhaps no longer even deserves such a title, given that flowing slurries (a very common phenomena!) can produce the same basic features simultaneously.
Actually, it doesn't. See my earlier post.
OK - i need to clarify where you're coming from here, edge.
Are you saying that there are details that apparently differentiate water-formed simultaneous strata from wind-formed strata? On that i'd agree - there is boudn to be differentiating signatures...but it seems that you are suggesting that the water-formed simultaneous strata bear VERY LITTLE resemblence at all to what would be conventionally labelled wind-formed strata?
Like i conceeded before - i'm not up on all the details, and how they might feature in differentiation...but also consider that any idiot (me, perhaps?) can see that there are some very significant, major similarities, and that i would think any idiot would be hesitant to dismiss them so casually...For example, the water-formed simultaneous mechanisms can produce:
i) parallel stratum
ii) cross-bedding
iii) inter-bedding
iv) angles of repose for cross-beds normally/conventionally interpreted as being categorically wind-derived
When so many major features have their boxes ticked "yes", how can one so easily dismiss it?
Given such weight, isn't when compelled to consider, then, that, if we consider the hypothesis of high-energy water-dynamics as a theoretical starting point, it is reasonably possible that the finer details that are said to differentiate the strata as "necessarily wind-blown" might infact be conceivably (and even experimentally!) explained in another light?
Could you conceed that my reasoning at least has some merit?
Regards.

This message is a reply to:
 Message 117 by edge, posted 01-06-2010 11:10 PM edge has replied

Replies to this message:
 Message 129 by edge, posted 01-08-2010 10:30 AM stewartreeve has not replied
 Message 140 by Dr Adequate, posted 01-11-2010 2:00 PM stewartreeve has not replied

  
stewartreeve
Junior Member (Idle past 5190 days)
Posts: 10
From: Central Coast, NSW, Australia
Joined: 01-06-2010


Message 123 of 156 (542197)
01-08-2010 9:11 AM
Reply to: Message 119 by Coragyps
01-07-2010 12:07 PM


Hopefully the clay-settling notion (of being slow) is also not a "Principle" (though i do hear that A LOT!), as isn't even the norm...i still scratch my head at why geos keep saying it's so....it's just not....
Geologists and oceanographers putting sediment traps in the bottom of bodies of water and actually measuring how sediment accumulates may have a lot to do with why they say that. And ferric chloride, or polyacrylamide, or polyDADMAC aren't really that abundant in natural waters, anyway.
Mind you, Cora, from what i understand of a sediment trap, it can only give an indication of the unit mass collected per unit time, not the unit distance settled of a given particle per unit time (which is settling rate, what we're talking about).
As for the chemicals you've listed that can (and often are) used by engineers to induce coagulation and flocculation (though the listed chemicals are mainly primary coagulants, not primary flocculants...beside the point, yes ).

This message is a reply to:
 Message 119 by Coragyps, posted 01-07-2010 12:07 PM Coragyps has not replied

  
PaulK
Member
Posts: 17822
Joined: 01-10-2003
Member Rating: 2.2


Message 124 of 156 (542200)
01-08-2010 9:32 AM
Reply to: Message 121 by stewartreeve
01-08-2010 8:49 AM


quote:
Doesn't the Principle of Superposition have the following corollary/necessary implication (paraphrased):
"For any given vertical coordinate in a layer, it follows that any given horizontal point is said to be deposited at the same time, and thus, has the same age" (yes? no? am i mixed up with the Principle of Original Horizontality? Don't think so, but i should ask...)
Unless you assume horizontality very strongly, that can't be true. If the sediment was deposited at an angle, the layer will necessarily include points that were deposited at the same time at different vertical levels. That's simple geometry.
And while I'm no geologist the Principle seems to be about the relationship between layers, rather than the relationships between the particles that make up a layer:
Sedimentary layers are deposited in a time sequence, with the oldest on the bottom and the youngest on the top.
(from Wikipedia)
So I'm not convinced that there are true exceptions to the Principle - in my view there are only cautions on applying it outside of a strictly vertical context.

This message is a reply to:
 Message 121 by stewartreeve, posted 01-08-2010 8:49 AM stewartreeve has replied

Replies to this message:
 Message 127 by stewartreeve, posted 01-08-2010 10:24 AM PaulK has replied

  
stewartreeve
Junior Member (Idle past 5190 days)
Posts: 10
From: Central Coast, NSW, Australia
Joined: 01-06-2010


Message 125 of 156 (542206)
01-08-2010 10:09 AM


Coagulation and Flocculation
OK, first up, look at references, don't just listen to me...here is a good references i dug up for a geo acquaintance recently (there was others, but this was the best freebie!):
Coagulation and flocculation in water and wastewater treatment
By John Bratby
Error 404 (Not Found)!!1
...i actually might buy that book - it's some of the best material on the topic i've ever read, actually
Oh, and a note, someone brought up recently that i was using the notion of flocculation to disprove the Lake Shigetsu varve interpretations - i actually did not such thing...i merely corrected a comment previous to that original correction, which asserted that clays necessarily settled slowly. That's it. I did not comment on the Lake Shigetsu info at all, initially.
Anyhow, for a briefer explanation from me re: how does coagulation and flocculation affect clay and silt settling rates? Under what conditions does coagulation and flocculation occur?
hmmm...how to do this briefly?
Ok, basics:
- the smaller particles get, the more significant (surface area to volume ratio) the surface electrical layer repulsion becomes WRT the mass of the particle
- i'd take a stab and say that particles < 150 micron (in very general! mining guy here!) are where we start to really see dispersive particle behaviour really start to kick in. It's the electrical field that does the particle-particle repulsion, and keeps particles "suspened'/stable in water.
- the field characteristics are generally well-correlated to a quanitity known as the "Zeta Potential" - the stronger the zeta-potential, the stronger the field of charge, and the stronger the repulsive effect. Note that the electrical field can be net negative or net positive (or can be ~ zero!...more on that later...)
- what is Coagulation? Basically: It is the reduction of the strength of the repulsive field surrounding the particle, such that particle-particle interaction can occur
- what is flocculation? Basically: It is the agglomeration of particles with their fields of charge sufficiently reduced (now that is a geo-specific deinfition...water treatment lingo/theory generally collapses this definition of flocculation into the definition of coagulation, and redefines "flocculation" as relating to the "bridging"-type agglomeration of particles ("flocs") by a chemical-bridge - normally a high-molecular weight organic molecule, such as a synthetic polymer, but also inorganic polymers such as poly-aluminium chloride amd activated silica).
- factors affecting the strength of the electrical field include (but are not necessarily limited to): i) particle-specific geo-chemistry; ii) size of the particle; iii) water chemistry
- as you can gather from the above list of only three items, the range of affects is HUGE - so the answer to the question, "What conditions are conducive to coagulation and flocculation" is also HUGE if we focus on these factors...there are MANY, MANY different combinations for coagulation and flocculation of a specific particle(s)...but the best way of expressing it is with that single quantity: ZETA-POTENTIAL
- when Zeta-potential is lowered from a "high" net-negative or net-positive state (ie. ZP approaches zero), particles can interact and agglomerate. A zero value is not NEEDED necessarily - just what is "needed" is the reduction of the repulsive forces between particles so that they can agglomerate. ZP ~ 0 is a good guide, though, and many particle systems have best agglomeration around this value.
- some particles - like clays such as kaolinite, with their charged platelet surfaces - tend to "self-flocculate", which for us means that they will tend to agglomerate more easily, over wider ranges of water chemistry
- but it is true that the most common mechanisms (in industry, as well as nature) that coagulation and flocculation occur is by the appropriate ranges of water chemistry and assistance kinetic energy (ie. mixing) being present
- water chemistry: pH (or "bulk affect") is important - any fine particle system will have the "positiveness" or "negativeness" of water of a particular pH affect the zeta-potential. A given particle system will have a range (often fairly wide) where pH affects alone will, in conjunction with a little mixing, induce coagulation and flocculation
- water chemistry: typically, most particle systems have a net-negative charge...thus, the presence of dissolved cations in the water are of particular interest....ie. ANY dissolved cation...sodium, potassium, calcium, iron, magnesium, aluminium, cobalt, strontium...anything....all become "coagulants" and can induce coagulation if the right concentrations are present. Similarly, over-concentration of cations can actually "re-suspend" a particle by creating a neg-popsitve charge....so it's just reversed the problem However, that normally takes a very high concentration of cations.
- the coagulative potential of a cation is directly proportional to the sixth power of the valance (pretty sure that's right!)...definitely very exponential, that's for sure.
- This implies that, with adequate mixing for increased chemical-particle-particle interaction, sodium(1+), for example can perform the task, but calcium(2+) is far more effective, and iron(3+ in this case) is more effective again, and vanadium (5+) is far more effective again...and the efficiency trend is exponential.
- applying it briefly: sea-water should generally coagulate (high sodium(1+) concentration
- a little bit of mixing goes a long way (not much required; make up for energy with time!); and is an important factor is coagulation and flocculation, and "floc" stability
- someone also mentioned that making the size of the particle larger shouldn't affect it too much, as it wasn't related to density, as if this should invalidate the signficance of agglomeration to fine particle settling rates. Not so: look at the basic Stokes Equation for Terminal Velocity in a viscous fluid as a guide (laminar flow assumption, Stokes' law - Wikipedia): the terminal velocity in linearly proportional to the density of the particle, but proportional to the SQUARE of the diameter (read-in hydrodynamic diamter, as we are not dealing with spheres in the real world).
- FINAL COMMENT: it is the prevalence of either favourable cation concentrations (which don't even need to be that high!), and/or favourable pHs, and abundance of natural mixing environments that assist chemical-particle-particle collisions, that makes coagulation and flocculation of fine particles (silts and clays, etc) so common in the natural world.
I really hope that was at least interesting to someone! Should i at least give myself a gold star for effort? lol
Regards.
Stewart

Replies to this message:
 Message 126 by Percy, posted 01-08-2010 10:20 AM stewartreeve has replied

  
Percy
Member
Posts: 22392
From: New Hampshire
Joined: 12-23-2000
Member Rating: 5.3


Message 126 of 156 (542208)
01-08-2010 10:20 AM
Reply to: Message 125 by stewartreeve
01-08-2010 10:09 AM


Re: Coagulation and Flocculation
stewartreeve writes:
Oh, and a note, someone brought up recently that i was using the notion of flocculation to disprove the Lake Shigetsu varve interpretations - i actually did not such thing...i merely corrected a comment previous to that original correction, which asserted that clays necessarily settled slowly. That's it. I did not comment on the Lake Shigetsu info at all, initially.
Uh, not that coagulation and flocculation aren't fascinating, but unless you can tie them into evidence for your position, such as how they affect the interpretation of the Lake Suigetsu (not Shigetsu) varves, discussion of them doesn't really belong in this thread.
--Percy

This message is a reply to:
 Message 125 by stewartreeve, posted 01-08-2010 10:09 AM stewartreeve has replied

Replies to this message:
 Message 128 by stewartreeve, posted 01-08-2010 10:29 AM Percy has seen this message but not replied

  
stewartreeve
Junior Member (Idle past 5190 days)
Posts: 10
From: Central Coast, NSW, Australia
Joined: 01-06-2010


Message 127 of 156 (542209)
01-08-2010 10:24 AM
Reply to: Message 124 by PaulK
01-08-2010 9:32 AM


quote:
--------------------------------------------------------------------------------
Doesn't the Principle of Superposition have the following corollary/necessary implication (paraphrased):
"For any given vertical coordinate in a layer, it follows that any given horizontal point is said to be deposited at the same time, and thus, has the same age" (yes? no? am i mixed up with the Principle of Original Horizontality? Don't think so, but i should ask...)
--------------------------------------------------------------------------------
Unless you assume horizontality very strongly, that can't be true. If the sediment was deposited at an angle, the layer will necessarily include points that were deposited at the same time at different vertical levels. That's simple geometry.
And while I'm no geologist the Principle seems to be about the relationship between layers, rather than the relationships between the particles that make up a layer:
Sedimentary layers are deposited in a time sequence, with the oldest on the bottom and the youngest on the top.
(from Wikipedia)
So I'm not convinced that there are true exceptions to the Principle - in my view there are only cautions on applying it outside of a strictly vertical context.
PaulK, i see your point, but i think the correction is quite trivial....perhaps i should re-phrase it as relating to the same relative or proportional point in the same layer?
Nonetheless, the point is that vertically-successive strata can be formed by a simultaneous, dynamic mechanism, by HORIZONTAL progression- and said strata, if analysed "blind", would conventionally be interpreted as forming one layer after another: the lowest first, then the next, then the next, and so on, according to the normal rendering of the Principle of Superposition; whilst the truth of the matter would be that the stratum were all formed at the same time: with the "youngest" part being at the horizontal "start", and not at the vertical "start" (bottom)...
This is a thought-experiment to help convey my point...
Also, if people want to appeal to a particle-by-particle deposition for the dynamic scenario as still validating the general Principle of Superposition, then i'd have to remind them (and myself!) that the principle is concerned with the inter-stratum chronology - true? Thus, this appeal would reduce the necessary validity of the PoSn to only having intra-stratum relevance, instead of the inter-stratum relevance it is intended to have.
I really have to stop and go to bed....thanks for your patience...
Stewart

This message is a reply to:
 Message 124 by PaulK, posted 01-08-2010 9:32 AM PaulK has replied

Replies to this message:
 Message 130 by edge, posted 01-08-2010 10:44 AM stewartreeve has not replied
 Message 131 by PaulK, posted 01-08-2010 11:36 AM stewartreeve has not replied

  
stewartreeve
Junior Member (Idle past 5190 days)
Posts: 10
From: Central Coast, NSW, Australia
Joined: 01-06-2010


Message 128 of 156 (542211)
01-08-2010 10:29 AM
Reply to: Message 126 by Percy
01-08-2010 10:20 AM


Re: Coagulation and Flocculation
stewartreeve writes:
Oh, and a note, someone brought up recently that i was using the notion of flocculation to disprove the Lake Shigetsu varve interpretations - i actually did not such thing...i merely corrected a comment previous to that original correction, which asserted that clays necessarily settled slowly. That's it. I did not comment on the Lake Shigetsu info at all, initially.
Uh, not that coagulation and flocculation aren't fascinating, but unless you can tie them into evidence for your position, such as how they affect the interpretation of the Lake Suigetsu (not Shigetsu) varves, discussion of them doesn't really belong in this thread.
--Percy
No, it's not relevant to this discussion. The whole clay/silt settling thing was initially a tangent, a comment i made on someone else's comment, that someone else decided (kind of randomly and definitely tangentially!) that it was relevant to Lake Shigetsu - perhaps i shouldn't have said anything? I apologise - i'll happilly stop discussing the topic if no one wants to discuss it IN GENERAL any further.
The Lake Shigetsu thingy is a strong point - great, i'll give you that. But i'm sure not obliged to discuss it in this thread (and i'd be silly to, given how little i know about it! Mind you, RAZD's post looks really good, and has lots of info...i'll go back to that sometime Ta)
Now let me go to bed
Edited by stewartreeve, : No reason given.

This message is a reply to:
 Message 126 by Percy, posted 01-08-2010 10:20 AM Percy has seen this message but not replied

Replies to this message:
 Message 132 by RAZD, posted 01-08-2010 6:40 PM stewartreeve has not replied

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


Message 129 of 156 (542212)
01-08-2010 10:30 AM
Reply to: Message 122 by stewartreeve
01-08-2010 9:06 AM


OK - i need to clarify where you're coming from here, edge.
Are you saying that there are details that apparently differentiate water-formed simultaneous strata from wind-formed strata? On that i'd agree - there is boudn to be differentiating signatures...but it seems that you are suggesting that the water-formed simultaneous strata bear VERY LITTLE resemblence at all to what would be conventionally labelled wind-formed strata?
Let's just say that the differences are more obvious to the trained eye. For instance, some of your references do not seem to be very detailed in the composition of some of the cross-bedded deposits they depict.
Like i conceeded before - i'm not up on all the details, and how they might feature in differentiation...but also consider that any idiot (me, perhaps?) can see that there are some very significant, major similarities, and that i would think any idiot would be hesitant to dismiss them so casually...For example, the water-formed simultaneous mechanisms can produce:
i) parallel stratum
ii) cross-bedding
iii) inter-bedding
iv) angles of repose for cross-beds normally/conventionally interpreted as being categorically wind-derived
When so many major features have their boxes ticked "yes", how can one so easily dismiss it?
Who is dismissing it? You are creating a strawman here. I'm saying that my experience looking at eolian deposits of the Colorado Plateau show that there are some differences that are best explained by depositional environment.
Given such weight, isn't when compelled to consider, then, that, if we consider the hypothesis of high-energy water-dynamics as a theoretical starting point, it is reasonably possible that the finer details that are said to differentiate the strata as "necessarily wind-blown" might infact be conceivably (and even experimentally!) explained in another light?
Now it appears that YOU are the one ignoring evidence...
Could you conceed that my reasoning at least has some merit?
If you are saying that there are some similarities and there are some disimilarities, then yes, your statement has merit. However, it appears more to me that you are picking the evidence you want to address.
Of your 4 features listed above, I did not use one of them to discriminate between eolian and aquatic deposition.
What you seem to be saying is that if orangutans have two arms, two legs, and opposable thumbs they are probably the same as humans. So, does that make sense?

This message is a reply to:
 Message 122 by stewartreeve, posted 01-08-2010 9:06 AM stewartreeve has not replied

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


Message 130 of 156 (542216)
01-08-2010 10:44 AM
Reply to: Message 127 by stewartreeve
01-08-2010 10:24 AM


PaulK, i see your point, but i think the correction is quite trivial....perhaps i should re-phrase it as relating to the same relative or proportional point in the same layer?
Well to me, your complaint seems trivial. In every case a stratum is younger than the one beneath it, regardless of the scale. Your point is conflating the scales of observation.
Nonetheless, the point is that vertically-successive strata can be formed by a simultaneous, dynamic mechanism, by HORIZONTAL progression- and said strata, if analysed "blind", would conventionally be interpreted as forming one layer after another: the lowest first, then the next, then the next, and so on, according to the normal rendering of the Principle of Superposition; whilst the truth of the matter would be that the stratum were all formed at the same time: with the "youngest" part being at the horizontal "start", and not at the vertical "start" (bottom)...
Actually, no. In cross-bedded strata, we look at the cross-laminations as the chronological break.
This is a thought-experiment to help convey my point...
Your point is based on misunderstanding.
Also, if people want to appeal to a particle-by-particle deposition for the dynamic scenario as still validating the general Principle of Superposition, then i'd have to remind them (and myself!) that the principle is concerned with the inter-stratum chronology - true?
If I read your intentions correctly, yes.
Thus, this appeal would reduce the necessary validity of the PoSn to only having intra-stratum relevance, instead of the inter-stratum relevance it is intended to have.
Again, no, because the time-equivalent discontinuities are cross-bedded.

This message is a reply to:
 Message 127 by stewartreeve, posted 01-08-2010 10:24 AM stewartreeve has not replied

  
PaulK
Member
Posts: 17822
Joined: 01-10-2003
Member Rating: 2.2


Message 131 of 156 (542227)
01-08-2010 11:36 AM
Reply to: Message 127 by stewartreeve
01-08-2010 10:24 AM


quote:
PaulK, i see your point, but i think the correction is quite trivial....perhaps i should re-phrase it as relating to the same relative or proportional point in the same layer?
That solves one problem, but it does potentially raise other issues (for instance, when did deposition start ? is it occurring at the same rate ?). The point is that you must add other assumptions, beyond superposition to identify the order when you include horizontal displacement.
quote:
Nonetheless, the point is that vertically-successive strata can be formed by a simultaneous, dynamic mechanism, by HORIZONTAL progression- and said strata, if analysed "blind", would conventionally be interpreted as forming one layer after another: the lowest first, then the next, then the next, and so on, according to the normal rendering of the Principle of Superposition; whilst the truth of the matter would be that the stratum were all formed at the same time: with the "youngest" part being at the horizontal "start", and not at the vertical "start" (bottom)...
I have to disagree. The vertical relationships all obey the Law of Superposition. It's just that the time involved is small. It would be more true to say that the deposition of the strata overlap and assigning a precise age to the whole stratum could be misleading. I'll also add that the sort of scenarios you seem to be proposing look to me to be small scale - both in terms of geographical area and time - and so not likely to be a big problem for geology.
quote:
Also, if people want to appeal to a particle-by-particle deposition for the dynamic scenario as still validating the general Principle of Superposition, then i'd have to remind them (and myself!) that the principle is concerned with the inter-stratum chronology - true? Thus, this appeal would reduce the necessary validity of the PoSn to only having intra-stratum relevance, instead of the inter-stratum relevance it is intended to have.
I don't think it does. That is, the particle-by-particle argument works in the same way whether the particles are part of the same layer or not. In every case the particle on top needs to arrive after the one on the bottom. The restriction that the argument does impose is that we are limited to strict vertical sections - however these sections can include any number of layers.
However, your idea of horizontal levels marking the same time runs into even bigger trouble if it is used between different layers. If the older layer is eroded unevenly, later sediment may be deposited into holes and gullies, arriving at the same horizontal level as sediment from the older layer.
So, I think all that can be said is that we need some caution when considering the horizontal dimension. In a strict vertical sense superposition works, unless the newer particles have some way of getting under the older particles already deposited.
Edited by PaulK, : Fixed broken sentence

This message is a reply to:
 Message 127 by stewartreeve, posted 01-08-2010 10:24 AM stewartreeve has not replied

  
RAZD
Member (Idle past 1405 days)
Posts: 20714
From: the other end of the sidewalk
Joined: 03-14-2004


Message 132 of 156 (542313)
01-08-2010 6:40 PM
Reply to: Message 128 by stewartreeve
01-08-2010 10:29 AM


On the timelyness of replies and focus on the topic
Hi again stewartreeve, still slugging away eh?
The Lake Shigetsu thingy is a strong point - great, i'll give you that. But i'm sure not obliged to discuss it in this thread (and i'd be silly to, given how little i know about it! Mind you, RAZD's post looks really good, and has lots of info...i'll go back to that sometime Ta)
I suggest sooner rather than later, as you seem to be going down a rather pointless rabbit-hole.
In Message 113 it was pointed out that this thread is about how geological principles are applied to understand evidence:
This thread is about explaining the basics of geology, and is not a thread to debate the results.
You are still arguing about the latter and ignoring the former.
The principle in question is the law of superposition (Message 1):
quote:
The first thing I would like to deal with is the law of superposition. This states that sedimentary layers form in a time progressive sequence with the oldest layers at the bottom and the youngest on the top. To view this simply, picture stacking books one on top of the other- the book you put down first will by at the bottom of the pile, and the book you put down last will be at the top. Can we agree this principle is sound?
You appear to be arguing that this may not be sound in all cases due to your premise that some apparently horizontal depositions may be formed by Berthault's dynamic flow deposition, with quick settling materials (granular sands, for example), even though this is only demonstrated in very small scale experiments and can only apply in certain special circumstances.
In Message 113 I noted:
quote:
Certainly it is incapable of explaining alternate layers of silty clay (which takes a long time to deposit) and diatom shells (which fall fast) as seen in Lake Suigetsu in Japan (see Age Correlations and An Old Earth, Version 2 No 1, Message 5).
It appears that you agreed that Bertault's flume flow would not apply to Lake Suigetsu (note S•U•I•G•E•T•S•U):
Message 116: Aha...sorry, not true. Silty clay does not necessarily take a long time to deposit - this assumes a Stokian settling regime, considering dry particle hydrodynamic diameter and density only; it does not consider the very significant impact of water chemistry on these colloidal and near-colloidal size particles. But it's good you brought it up.
Coagulation and flocculation ...
You did not dispute that the dynamic system, aka Bertault, was incapable of explaining this deposit, but instead changed to a different mechanism. You are now proposing fast settling of clay deposits by some hypothetical flocculation mechanism.
This means that the law of superposition de facto applies to the Lake Suigetsu deposits, and all we are arguing about is the rate of deposition - the results and not the principle of geology, in this case the law of superposition.
Further, Message 120 describes in detail how superposition accurately explains (all) the evidence and that no other known mechanism explains (all) the evidence.
In other words your original premise has been shown to not apply in one case (of many that are similar in nature to the Lake Suigetsu deposits), and we can agree that the principle of superposition is indeed sound in this case.
Curiously that is the point of the topic, and further discussion is rather off topic.
Message 116: As a result, particles can have their settling rates increased by orders of magnitude WRT their calculated Stokes Settling rates. It has not been uncommon for me to see colloidal clays with Stokes Settling rates of years per metre accelerated to metres per minute with the appropriate water chemistry (HUGE range! normal!), and a little agitation (for particle-particle agglomeration opportunity). It's really, really easy to do, too, and happens readily.
This turns out to be a red herring logical fallacy, for several reasons - not least of which is that what can occur under certain controlled circumstances cannot be assume to apply to any natural system without first showing that it is possible - and it ignores the actual physical evidence from Lake Suigetsu.
Interestingly, Message 120 also shows that the rates of sedimentation could not have been increased in any significant amount by hypothetically adding imagined flocculation chemicals, because the diatoms exhibit an annual variation independent of chemical additives that results in the alternating layers. It also shows independent evidence that correlates with and corroborates the annual deposition process, thus demonstrating that there was no increased rate of sedimentation.
Thus your second premise is also shown to be of no value.
Not only does this additional data confirm the annual deposits, but it also confirms the principle of superposition:
Every layer that was dated was indeed organized by youngest on top and oldest on the bottom.
The "law of superposition" is thereby confirmed as a sound principle for use in geology.
Message 121: ... but there are also things i do understand well, such as arguement/logic structure, ...
Then you should recognize that the "law of superposition" is confirmed as a logical principle and any further posting on this issue is moot and off-topic.
If you want to pursue Bertault's conjecture further, I suggest a new topic with an example of where it could be observed in a known deposit.
Enjoy.

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This message is a reply to:
 Message 128 by stewartreeve, posted 01-08-2010 10:29 AM stewartreeve has not replied

Replies to this message:
 Message 133 by petrophysics1, posted 01-11-2010 7:56 AM RAZD has seen this message but not replied

  
petrophysics1
Inactive Member


(1)
Message 133 of 156 (542607)
01-11-2010 7:56 AM
Reply to: Message 132 by RAZD
01-08-2010 6:40 PM


Re: On the timelyness of replies and focus on the topic
Hi RAZD,
If you want to pursue Bertault's conjecture further, I suggest a new topic with an example of where it could be observed in a known deposit.
Actually that is not necessary. You see RAZD, you have taken the bait, like most others, because you are not a geologist.
This is merely an expierment which shows the deposition of a classic Gilbert delta. It was first described and explained by G.K.Gilbert looking at a delta at Lake Bonneville, Utah in 1885.
Yes, that is correct. This deposition has been known to geologists for 125 years. It is taught in introductory stratigraghy because its the simpilest form of deltaic deposition.
It's not something new, an expierment done in 1998 or 2007 which shows something we geologists knew for the last 125 years is not ground breaking news. However, if you are not a geologist, you might buy the shit that this is something geology hasn't noticed.
You fell for it in part but our chemical engineer friend in Australia grabbed it hook, line and sinker.
The following is important.
Formations and their boundaries ARE NOT time lines. In special instances they could be, but in general they are not.
Let me explain this using the Mississippi delta today. I'm going to simplify it a bit to make it easier to understand.
A time line is the surface of the earth today, right now.
If we look at the Mississippi River and delta system right now, we see many different types of deposition occuring at the EXACT same time.
North of New Orleans we have river deposits, point bars, cravasse splays, oxbow lakes along with all the associated plants, animals, organic material and sediments we see in this environment. Let's call this "River Deposits".
South of New Orleans as we approach the coast we have swamp deposits. Low areas with lots of water having abundant plant life but not strong sand deposition except in some small areas.Let's call this "Swamp Deposits".
At the mouth of the Mississippi River it is dumping sand into the standing water of the Gulf of Mexico. This sand being deposited is called a destributary mouth bar(DMB). It has like the river and swamp areas a particular sand deposition, along with associated plants, animals, and organic material.
Farther out to sea, the sand can't make it out there. We see very fined grained sediments. Clays and some silts. NOTE: clay, silt, sand and gravel ARE GRAIN SIZES, they have nothing to do with a particular grains mineralogy. These sediments we will call "pro-delta".
Now lets look at what happens as this complex progrades out into the Gulf Of Mexico trying to fill it in. All of these environments will move seaward if the delta is prograding/trying to fill in the Gulf of Mexico.
At some point in time the river deposits will be where the mouth of the river is now. At that point if we drill a well, we will see in our core or cutting , from the top down....
1.river deposits
2.swamp deposits
3.distributary mouth bar deposits
4.pro-delta deposits
Now, a formation is a unit which can be mapped.
So I might map the river deposits as a formation, but I never think they all happened at the same time. Nor does any other geologist.
If I am looking, in a borehole or vertical section at the rocks, I know that everything in this borehole from bottom to top goes from older to younger, unless I have a recumbent fold or a reverse fault I passed through.
So in a vertical section, a borehole or a measured section, I know that the DMB is older that the river deposits, but that upsteam there are river deposits the same age as my DMBs.
Sorry, I have to go, I have to do my morning report on the 6 gas wells I'm drilling for EnCana Oil and Gas.
If you have a question I'll be back later.

This message is a reply to:
 Message 132 by RAZD, posted 01-08-2010 6:40 PM RAZD has seen this message but not replied

Replies to this message:
 Message 135 by Percy, posted 01-11-2010 9:04 AM petrophysics1 has replied
 Message 136 by Coragyps, posted 01-11-2010 9:28 AM petrophysics1 has replied

  
Dr Adequate
Member (Idle past 284 days)
Posts: 16113
Joined: 07-20-2006


Message 134 of 156 (542613)
01-11-2010 8:48 AM
Reply to: Message 121 by stewartreeve
01-08-2010 8:49 AM


Doesn't the Principle of Superposition have the following corollary/necessary implication (paraphrased):
"For any given vertical coordinate in a layer, it follows that any given horizontal point is said to be deposited at the same time, and thus, has the same age" (yes? no? am i mixed up with the Principle of Original Horizontality? ...
Apparently.
Consequently, the dynamic simultaneous deposition of layers potentially contradicts at least THIS interpretation/version of the Principle of Superposition, because it is possible to have the VERTICAL points being deposited at the same time ...
But it is not possible to have the stuff on the bottom deposited after the stuff on the top.

This message is a reply to:
 Message 121 by stewartreeve, posted 01-08-2010 8:49 AM stewartreeve has not replied

  
Percy
Member
Posts: 22392
From: New Hampshire
Joined: 12-23-2000
Member Rating: 5.3


Message 135 of 156 (542614)
01-11-2010 9:04 AM
Reply to: Message 133 by petrophysics1
01-11-2010 7:56 AM


Re: On the timelyness of replies and focus on the topic
petrophysics1 writes:
Formations and their boundaries ARE NOT time lines. In special instances they could be, but in general they are not.
Isn't this overstated when you say "special instances"? You used the example of the Mississippi and the Gulf of Mexico, but isn't the area around the margins of the Gulf dwarfed by the area of the Gulf itself? Aren't the intersections of major rivers like the Mississippi with major bodies of water like the Gulf of Mexico the exception rather than the rule? And if we're talking about millions of years rather than thousands of years, aren't a great many formations and their boundaries fairly useful time lines?
So if we're looking at sandstone deposits that formed just off the coast of a continent then as we move further and further way from the old continental margin we're looking at newer and newer sandstone deposits, but how many years are we talking about per horizontal mile? Not millions, surely.
And if we're looking at limestone deposits that formed in shallow seas far from the coast then they were pretty much deposited all at the same time, and limestone deposits are not "special instances."
--Percy

This message is a reply to:
 Message 133 by petrophysics1, posted 01-11-2010 7:56 AM petrophysics1 has replied

Replies to this message:
 Message 138 by petrophysics1, posted 01-11-2010 12:02 PM Percy has replied

  
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