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Author Topic:   Earth science curriculum tailored to fit wavering fundamentalists
Tanypteryx
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From: Oregon, USA
Joined: 08-27-2006
Member Rating: 5.9


(1)
Message 916 of 1053 (768713)
09-13-2015 11:35 AM
Reply to: Message 915 by edge
09-13-2015 11:08 AM


Re: Igneous rock over sedimentary layers
The issue would be the presence of significant unconformities beneath or above the lava flows. I would be very careful about either unless I was in a fairly continuous sequence of sediments briefly interrupted by a volcanic event.
In the case of a sill, the only relationship would be intrusive younger than sediments on either side.
Sure, that makes perfect sense.
I assume that ash layers are the best, from a geology dating standpoint, because they can cover much wider areas than lava flows.

What if Eleanor Roosevelt had wings? -- Monty Python
One important characteristic of a theory is that is has survived repeated attempts to falsify it. Contrary to your understanding, all available evidence confirms it. --Subbie
If evolution is shown to be false, it will be at the hands of things that are true, not made up. --percy

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


(1)
Message 917 of 1053 (768715)
09-13-2015 12:31 PM
Reply to: Message 916 by Tanypteryx
09-13-2015 11:35 AM


Re: Igneous rock over sedimentary layers
I assume that ash layers are the best, from a geology dating standpoint, because they can cover much wider areas than lava flows.
Indeed, and each volcano has a "signature" mix of minerals and elements so they can be compared and correlated. An ash layer in a peat bog in Japan is from the same volcanic eruption as one in Lake Suigetsu, and this can be used to validate the age of the layers in Lake Suigetsu or vice versa.
In addition sometimes artifacts or footprints are found in the tuff (Laetoli being a famous example) or killed by the ash cloud (as occurred at Pompeii) and thus they can be dated directly by the tuff.
Major eruptions also leave ash on glaciers or ice fields, and this allows those dates to be correlated.
Creationists love to intentionally do science badly because they know that they will get bollixed results which they can then foist on the gullible as "evidence" that the science is wrong. Time and again it is shown that all they have done is gotten the science wrong, as seen in the article TAD posted at the beginning of this subthread.
Enjoy
Note: you can follow subthreads by using the thread index and searching it for the subtitle (why subtitles are important?) -- click the little icon at the top left -- for this post I have changed it to
and on this thread it takes you to EvC Forum: Earth science curriculum tailored to fit wavering fundamentalists Message List

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This message is a reply to:
 Message 916 by Tanypteryx, posted 09-13-2015 11:35 AM Tanypteryx has seen this message but not replied

  
Admin
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From: EvC Forum
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Member Rating: 2.3


(1)
Message 918 of 1053 (768740)
09-13-2015 3:20 PM
Reply to: Message 914 by Faith
09-13-2015 7:51 AM


Moderator Provided Information
Precipitation and sedimentation are two different things. Precipitation is the result of a chemical reaction. Sedimentation is when solids suspended in a liquid fall out of suspension. The only way they're related is that after solids precipitate out of a solution via chemical reaction, those solids are then suspended in the liquid, and they will over time fall out of suspension, but they are called precipitates, not sediments.
There's an experiment anyone can perform that's been described to you many times. Take a few tablespoons of dirt and stir them into a large glass of water, then let it sit. While being stirred the dirt will remain suspended in the active and energetic water. Once the stirring stops there is no longer sufficient energy to maintain the larger particles in suspension and they will fall to the bottom, the larger first. Over time smaller and smaller particles will fall of suspension. The end result will be the dirt sorted by particle size, with the largest particles on the bottom and the smallest on the top.
It would be very unlikely for there to be no chemical reactions taking place in our dirt, but certainly not anything particularly noteworthy. There wouldn't be any expectation of noticeable precipitates.
In other words, the Earth's sedimentary layers consist primarily of sediments, not precipitates.

--Percy
EvC Forum Director

This message is a reply to:
 Message 914 by Faith, posted 09-13-2015 7:51 AM Faith has not replied

Replies to this message:
 Message 919 by NoNukes, posted 09-13-2015 10:11 PM Admin has replied

  
NoNukes
Inactive Member


(1)
Message 919 of 1053 (768774)
09-13-2015 10:11 PM
Reply to: Message 918 by Admin
09-13-2015 3:20 PM


Re: Moderator Provided Information
Precipitation and sedimentation are two different things. Precipitation is the result of a chemical reaction.
I am tutoring several young folks in chemistry this semester, so perhaps I am overly sensitive, but I think your definition is just a tiny bit narrower than the one used in chemistry. From the wikipedia artilce (emphasis added by me).
Precipitation - Wikipedia(chemistry)
quote:
Precipitation is the creation of a solid. When the reaction occurs in a liquid solution, the solid formed is called the 'precipitate'.
Sometimes the formation of a precipitate indicates the occurrence of a chemical reaction. If silver nitrate solution is poured into a solution of sodium chloride, a chemical reaction occurs forming a white precipitate of silver chloride. When potassium iodide solution reacts with lead nitrate solution, a yellow precipitate of lead iodide is formed.
Precipitation may occur if the concentration of a compound exceeds its solubility (such as when mixing solvents or changing their temperature). Precipitation may occur rapidly from a supersaturated solution.
As I understand it, even a non-ionic substance, when coming out of a solution due to change in solubility or temperature may be precipitation. However in the case of a non-ionic substance no chemical reaction has taken place.

Under a government which imprisons any unjustly, the true place for a just man is also in prison. Thoreau: Civil Disobedience (1846)
History will have to record that the greatest tragedy of this period of social transition was not the strident clamor of the bad people, but the appalling silence of the good people. Martin Luther King
If there are no stupid questions, then what kind of questions do stupid people ask? Do they get smart just in time to ask questions? Scott Adams

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 Message 918 by Admin, posted 09-13-2015 3:20 PM Admin has replied

Replies to this message:
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Admin
Director
Posts: 12998
From: EvC Forum
Joined: 06-14-2002
Member Rating: 2.3


Message 920 of 1053 (768778)
09-13-2015 10:43 PM
Reply to: Message 919 by NoNukes
09-13-2015 10:11 PM


Re: Moderator Provided Information
Yes, of course, there's also supersaturation - salt deposits, for example. But they're not sedimentary. If you think it's relevant to what Faith was trying to say then go ahead and work it into the discussion, but from context it seemed to me that Faith was using the wrong term. What she said was, "...both must have precipitated out of water as all the other sediments did," and the vast majority of sediments in the geological record are not precipitates but just erosion products washed and blown down from higher elevations.

--Percy
EvC Forum Director

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 Message 919 by NoNukes, posted 09-13-2015 10:11 PM NoNukes has not replied

Replies to this message:
 Message 921 by petrophysics1, posted 09-14-2015 8:13 AM Admin has replied

  
petrophysics1
Inactive Member


Message 921 of 1053 (768810)
09-14-2015 8:13 AM
Reply to: Message 920 by Admin
09-13-2015 10:43 PM


Re: Moderator Provided Information, that's wrong
Percy,
A precipitate is a sediment and as such it is sedimentary. Limestone can be the result of chemical precipitation, biological activity, or clastic deposition or combinations of these. So salt, anhydrite, gypsum, limestone and dolomite are sedimentary.
Read your geology glossary on what a sediment is.
Thanks

This message is a reply to:
 Message 920 by Admin, posted 09-13-2015 10:43 PM Admin has replied

Replies to this message:
 Message 923 by Admin, posted 09-14-2015 10:50 AM petrophysics1 has not replied
 Message 927 by Dr Adequate, posted 09-14-2015 11:43 AM petrophysics1 has not replied

  
ThinAirDesigns
Member (Idle past 2374 days)
Posts: 564
Joined: 02-12-2015


(1)
Message 922 of 1053 (768816)
09-14-2015 10:14 AM


So cool the stuff I learn here just watching the back and forth.
Thanks
JB

  
Admin
Director
Posts: 12998
From: EvC Forum
Joined: 06-14-2002
Member Rating: 2.3


Message 923 of 1053 (768823)
09-14-2015 10:50 AM
Reply to: Message 921 by petrophysics1
09-14-2015 8:13 AM


Re: Moderator Provided Information, that's wrong
petrophysics1 writes:
A precipitate is a sediment and as such it is sedimentary.
Yes, of course, but the point I was making to Faith is that the sedimentary layers we're usually discussing (e.g., Grand Canyon layers) did not originate as precipitates, and so did not precipitate out of solution as Faith describes. Layers like the Tapeats and the Muav and the Coconino and so forth are the ones usually being discussed. Can the sediments making up those layers be accurately described as precipitates? I don't think so, and so when Faith in her Message 914 postulated that diatomite and volcanic tuff layers "precipitated out of water as all the other sediments did," I provided correct information. Those layers were not formed (for the most part) from material precipitating out of solution and falling as sediments to the bottom. They were formed (for the most part) by suspended material falling out of suspension.
I appreciate the additional detail, and I understand the desire for accuracy and precision, but the approach I'm trying to take is to coax the other side out of the crawling stage of understanding before asking them to walk or run. I understand there will be other opinions about the best approach, but that's the one I've chosen.

--Percy
EvC Forum Director

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 Message 921 by petrophysics1, posted 09-14-2015 8:13 AM petrophysics1 has not replied

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 Message 924 by Faith, posted 09-14-2015 10:58 AM Admin has seen this message but not replied

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


Message 924 of 1053 (768824)
09-14-2015 10:58 AM
Reply to: Message 923 by Admin
09-14-2015 10:50 AM


Re: Moderator Provided Information, that's wrong
So they fell out of suspension, they dropped out of the water anyway. But limestones may precipitate out as petro said, and that would be the Tapeats and the Muav.

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 Message 923 by Admin, posted 09-14-2015 10:50 AM Admin has seen this message but not replied

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 Message 925 by edge, posted 09-14-2015 11:28 AM Faith has replied

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


Message 925 of 1053 (768829)
09-14-2015 11:28 AM
Reply to: Message 924 by Faith
09-14-2015 10:58 AM


Re: Moderator Provided Information, that's wrong
So they fell out of suspension, they dropped out of the water anyway. But limestones may precipitate out as petro said, and that would be the Tapeats and the Muav.
I don't think you intend to mention the Tapeats here. I've seen the Muav described as precipitated, but I'm not sure that's entirely accurate since few limestones are 'pure' and usually have a fine siliciclastic component.
Indeed, 'precipitate' would be a nonstandard usage in the rocks we are discussing, but it is also kind of vague. Often, I try to use the phrase 'chemical sediment' to avoid ambiguity.
I think that, for a layman, the confusion is understandable.
ETA: I have no problem with making the clarification, however.
Edited by edge, : No reason given.

This message is a reply to:
 Message 924 by Faith, posted 09-14-2015 10:58 AM Faith has replied

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


Message 926 of 1053 (768831)
09-14-2015 11:35 AM
Reply to: Message 925 by edge
09-14-2015 11:28 AM


Re: Moderator Provided Information, that's wrong
You are right, the Tapeats is sandstone and I shouldn't have included it.
I think that, for a layman, the confusion is understandable.
I would think so. One way or another it appears that the sedimentary particles dropped out of water, whether by precipitation or by falling out of suspension.

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


Message 927 of 1053 (768832)
09-14-2015 11:43 AM
Reply to: Message 921 by petrophysics1
09-14-2015 8:13 AM


Re: Moderator Provided Information, that's wrong
A precipitate is a sediment and as such it is sedimentary. Limestone can be the result of chemical precipitation, biological activity, or clastic deposition or combinations of these. So salt, anhydrite, gypsum, limestone and dolomite are sedimentary.
But we were talking about diatomite and volcanic tuff. They didn't precipitate. Percy's reply: "Precipitation and sedimentation are two different things. [...] The Earth's sedimentary layers consist primarily of sediments, not precipitates" is perfectly accurate. If he had said "THERE ARE NO PRECIPITATES IN THE GEOLOGICAL RECORD YOU FOOL", then he would have needed putting right.
Edited by Dr Adequate, : No reason given.

This message is a reply to:
 Message 921 by petrophysics1, posted 09-14-2015 8:13 AM petrophysics1 has not replied

Replies to this message:
 Message 928 by NoNukes, posted 09-14-2015 12:24 PM Dr Adequate has not replied
 Message 929 by Faith, posted 09-14-2015 1:02 PM Dr Adequate has replied

  
NoNukes
Inactive Member


Message 928 of 1053 (768844)
09-14-2015 12:24 PM
Reply to: Message 927 by Dr Adequate
09-14-2015 11:43 AM


Re: Moderator Provided Information, that's wrong
If he had said "THERE ARE NO PRECIPITATES IN THE GEOLOGICAL RECORD YOU FOOL", then he would have needed putting right.
There is no question that Faith's statement was imprecise. However Admin's correction lacked some precision as well (cleared up for the most part in his subsequent posts). I think petrophysics1 could rightly take issue with the following:
Admin writes:
It would be very unlikely for there to be no chemical reactions taking place in our dirt, but certainly not anything particularly noteworthy. There wouldn't be any expectation of noticeable precipitates.
What does in our dirt refer to? It appears to me not to refer to just the grand canyon, but to sedimentation in general. But even if we limit it to the GC, surely we can find gypsum, limestone and metal carbonates and sulphates in places in the Canyon. For example the Redwall and Muav includes limestone layers which are in part chemical sediments.

Under a government which imprisons any unjustly, the true place for a just man is also in prison. Thoreau: Civil Disobedience (1846)
History will have to record that the greatest tragedy of this period of social transition was not the strident clamor of the bad people, but the appalling silence of the good people. Martin Luther King
If there are no stupid questions, then what kind of questions do stupid people ask? Do they get smart just in time to ask questions? Scott Adams

This message is a reply to:
 Message 927 by Dr Adequate, posted 09-14-2015 11:43 AM Dr Adequate has not replied

Replies to this message:
 Message 930 by Admin, posted 09-14-2015 1:40 PM NoNukes has not replied

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


Message 929 of 1053 (768852)
09-14-2015 1:02 PM
Reply to: Message 927 by Dr Adequate
09-14-2015 11:43 AM


Re: Moderator Provided Information, that's wrong
But we were talking about diatomite and volcanic tuff.
So how do you explain the layering of the diatomite and tuff? The layers look like all the other layers which were deposited from water.

This message is a reply to:
 Message 927 by Dr Adequate, posted 09-14-2015 11:43 AM Dr Adequate has replied

Replies to this message:
 Message 931 by edge, posted 09-14-2015 2:00 PM Faith has not replied
 Message 932 by Dr Adequate, posted 09-14-2015 3:42 PM Faith has replied

  
Admin
Director
Posts: 12998
From: EvC Forum
Joined: 06-14-2002
Member Rating: 2.3


Message 930 of 1053 (768855)
09-14-2015 1:40 PM
Reply to: Message 928 by NoNukes
09-14-2015 12:24 PM


Re: Moderator Provided Information, that's wrong
The interest in accuracy and precision is laudable but isn't contributing to the discussion and may easily be causing confusion. My comments were made in the context of the discussion, where Dr Adequate asked Faith her reaction to an image that included diatomite and volcanic tuff layers:
In her reply Faith said that "both must have precipitated out of water as all the other sediments did." That is incorrect. It is untrue that all other sediments precipitated out of water. In fact, almost the opposite is true. The vast majority of sedimentary deposits around the world are not precipitates but ordinary sediments. I was only communicating this information to Faith.
If my manner of expression lacked accuracy or precision in the eyes of some, then please while correcting me at least keep one eye on the topic and put the corrective information in context.

--Percy
EvC Forum Director

This message is a reply to:
 Message 928 by NoNukes, posted 09-14-2015 12:24 PM NoNukes has not replied

  
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