Talk:Geologic ages of earth history: Difference between revisions

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==Headings==
{{subpages}}
== Absolute ages in schemes ==


Thomas, standard top-level headings are two equals signs; bold is not necessary. The reason it's two and not one is that single equals signs produce headings that are the same size as the title of the article --[[User:Larry Sanger|Larry Sanger]] 21:23, 15 April 2007 (CDT)
[[Image:Piecetimescale.jpg|thumb|500px|right|Something ''like this'', I mean...]]
Is anyone able to do something like this with schemes of time/rock subdivisions? It would be great. The alternative is to add a column to the tables with the absolute age of beginning for each subdivision, in Ma (million years ago). This latter solution would be, however, much less fancy. --[[User:Nereo Preto|Nereo Preto]] 13:19, 3 June 2007 (CDT)


Hi Larry, Right. Caught that after I had switched them back. Thought it was my oversight. But I reverted them. All article headings start at double equals and work down from there.  Thanks for the tip. - [[User:Thomas Simmons|Thomas Simmons]] 14:33 18 April, 2007 (EPT)
P.S.: an example of one more column is in the thread above, green-colored. I don't like it much. --[[User:Nereo Preto|Nereo Preto]] 13:23, 3 June 2007 (CDT)
:''Note: the green example is now stored in [[/Archive 1]]'' --[[User:Nereo Preto|Nereo Preto]] 02:25, 21 August 2007 (CDT)


== Change title to 'Geologic time scale'? ==
How does this look. (The code is far form beautiful, it's not an easy thing to do this.) [[User:Derek Harkness|Derek Harkness]] 20:49, 9 June 2007 (CDT)


Could we change the title of this article? To "Geologic time scale", I suggest.
<table class="wikitable" border="3" style="font-size:95%; border-collapse: separate; border-spacing: 0px;" cellpadding="0" cellspacing="0">
There are at least two reasons for this.


First, the description and classification of geologic time is usually found in Geologic time scales (what I also mean is that books about this topic are traditionally titled "Gologic time scale <year>", e.g., Gradstein F.M., Ogg J.G. and Smith A.G., 2004, A Geologic Time Scale 2004, Cambridge University Press).
<tr>
<th width="25%"> [[Erathem]]/[[Era]]
</th><th width="25%"> [[System]]/[[Period]]


Second, [[age (geology)|age]] has, in [[sedimentary geology|stratigraphy]], a precise meaning. Strictly speaking, the article "Geologic ages of earth history" should thus be a list of ages.
</th><th width="25%">[[Series]]/[[Epoch]]
</th>
<th width="25%">[[Stage]]/[[Age]] </th>
<th width="5">([[Ma]]) </th>
</tr>
<tr>
<td rowspan="13" style="border: 1px solid rgb(250,253,1);border-left: 20px solid rgb(250,253,1)">[[Cenozoic]]</td><td rowspan="13" style="border: 1px solid rgb(255,232,0);border-left: 20px solid rgb(255,232,0)">[[Neogene]]


This article is quite important for Earth Sciences. It might evolve into a description of the geologic time OR to a timeline of event in geologic time. I'll contribute soon (as soon as I can find the time). Thanks for starting it, for now! --[[User:Nereo Preto|Nereo Preto]] 01:57, 18 April 2007 (CDT)
</td><td style="border: 1px solid rgb(255,251,240);border-left: 20px solid rgb(255,251,240)">[[Holocene]]
</td>
<td style="border: 1px solid rgb(255,251,240);border-left: 20px solid rgb(255,251,240)">&nbsp;</td>
<td width="5"><div style=" position:relative; top:0.8em; width:5em; background-color:#FFFFFF;"><span style="font-size:0.75em">0.0118</span></div></td>
</tr>
<tr>
  <td rowspan="3" style="border: 1px solid rgb(255,247,176);border-left: 20px solid rgb(255,247,176)">[[Pleistocene]]
</td>
<td style="border: 1px solid rgb(255,247,176);border-left: 20px solid rgb(255,247,176)"> Upper/Late </td>
<td width="5" style="border-color:#FFFFFF;"><div style=" position:relative; top:0.8em; width:5em; background-color:#FFFFFF;"><span style="font-size:0.75em">0.126</span></div></td>
</tr>
<tr>
  <td style="border: 1px solid rgb(255,247,176);border-left: 20px solid rgb(255,247,176)"> Middle/Mid </td>
  <td width="5" style="border-color:#FFFFFF;"><div style=" position:relative; top:0.8em; width:5em; background-color:#FFFFFF;"><span style="font-size:0.75em">0.781</span></div></td>
</tr>


:The segmentation of time described, and the names of each segment, are not confined in their use only to geology. Biologists would also use many of these time classifications. Particularly within the study of Paleontology. Could this article be called the 'Classification of times'? [[User:Derek Harkness|Derek Harkness]] 04:53, 18 April 2007 (CDT)
<tr>
  <td style="border: 1px solid rgb(255,247,176);border-left: 20px solid rgb(255,247,176)">[[Lower/Early]] </td>
  <td width="5" style="border-color:#FFFFFF;"><div style=" position:relative; top:0.8em; width:5em; background-color:#FFFFFF;"><span style="font-size:0.75em">1.806</span></div></td>
</tr>
<tr>
  <td rowspan="3" style="border: 1px solid rgb(255,255,153);border-left: 20px solid rgb(255,255,153)">[[Pliocene]]
</td>
<td style="border: 1px solid rgb(255,255,153);border-left: 20px solid rgb(255,255,153)">[[Gelasian]] </td>
<td width="5" style="border-color:#FFFFFF;"><div style=" position:relative; top:0.8em; width:5em; background-color:#FFFFFF;"><span style="font-size:0.75em">2.588</span></div></td>
</tr>
<tr>
  <td style="border: 1px solid rgb(255,255,153);border-left: 20px solid rgb(255,255,153)">[[Piacenzian]] </td>
  <td width="5" style="border-color:#FFFFFF;"><div style=" position:relative; top:0.8em; width:5em; background-color:#FFFFFF;"><span style="font-size:0.75em">3.600</span></div></td>
</tr>
<tr>
  <td style="border: 1px solid rgb(255,255,153);border-left: 20px solid rgb(255,255,153)">[[Zanclean]] </td>
  <td width="5" style="border-color:#FFFFFF;"><div style=" position:relative; top:0.8em; width:5em; background-color:#FFFFFF;"><span style="font-size:0.75em">5.332</span></div></td>
</tr>
<tr>
  <td rowspan="6" style="border: 1px solid rgb(255,255,0);border-left: 20px solid rgb(255,255,0)">[[Miocene]]
</td>
<td style="border: 1px solid rgb(255,255,0);border-left: 20px solid rgb(255,255,0)">[[Messinian]] </td>
<td width="5" style="border-color:#FFFFFF;"><div style=" position:relative; top:0.8em; width:5em; background-color:#FFFFFF;"><span style="font-size:0.75em">7.246</span></div></td>
</tr>
<tr>
  <td style="border: 1px solid rgb(255,255,0);border-left: 20px solid rgb(255,255,0)">[[Tortonian]] </td>
  <td width="5"><div style=" position:relative; top:0.8em; width:5em; background-color:#FFFFFF;"><span style="font-size:0.75em">1234</span></div></td>
</tr>
<tr>
  <td style="border: 1px solid rgb(255,255,0);border-left: 20px solid rgb(255,255,0)">[[Serravallian]] </td>
  <td width="5""><div style=" position:relative; top:0.8em; width:5em; background-color:#FFFFFF;"><span style="font-size:0.75em">1234</span></div></td>
</tr>
<tr>
  <td style="border: 1px solid rgb(255,255,0);border-left: 20px solid rgb(255,255,0)">[[Langhian]] </td>
  <td width="5"><div style=" position:relative; top:0.8em; width:5em; background-color:#FFFFFF;"><span style="font-size:0.75em">1234</span></div></td>
</tr>
<tr>
  <td style="border: 1px solid rgb(255,255,0);border-left: 20px solid rgb(255,255,0)">[[Burdigalian]] </td>
  <td width="5"><div style=" position:relative; top:0.8em; width:5em; background-color:#FFFFFF;"><span style="font-size:0.75em">1234</span></div></td>
</tr>
<tr>
  <td style="border: 1px solid rgb(255,255,0);border-left: 20px solid rgb(255,255,0)">[[Aquitanian]] </td>
  <td width="5"><div style=" position:relative; top:0.8em; width:5em; background-color:#FFFFFF;"><span style="font-size:0.75em">1234</span></div></td>
</tr>
<tr>
  <td colspan="5">&nbsp;</td>
</tr></table>


Ok, let's do this: I'll take the time to collect some references and I'll post here soon some text about what could be this article about, and what should be its correct name in my view. I'll try to stick to authoritative sources. Then we'll discuss about it on the base of sources (of course, everyone who believes he has an argument is welcome to contribute! Don't take my step as something like "I'm the expert, shut up" please!)
It is a good start. Now if we could just get rid of borders and background in the last column... is there a help page or a handbook for wikitables? --[[User:Nereo Preto|Nereo Preto]] 03:21, 10 June 2007 (CDT)


The article of course can evolve under its current name for the moment. I suggest, however, to take a look at [[chronostratigraphy]], where I posted a table with all divisions of geologic time. Related articles may be also useful (see links there). --[[User:Nereo Preto|Nereo Preto]] 11:17, 18 April 2007 (CDT)
== List of perfectable things... ==


:The further the title gets from the actual topic, the more obscure it becomes and the less likely it will be spotted by the general public. The alternatives are semiotic artefacts of the sources which means if the reader is not familiar with the topic (one reason for coming here) they will miss these key words generated by very specialised literature. Redirects, however, are the best answer since they will fit a multitude of reader-contexts. If the literature shows a common use, then we simply put up a redirect. Piece of cake.
I am (slightly) passing this article throughout, to clean it up and make it look great. I open here a list of things that could be better. Add to list if you find problems, or strike the point if you find a solution!


:The limitations of the topic--in this case, geological--are the focus of the topic, but branching articles will of course make specific distinctions as would, say, palaeontology. The very names of the eras and other categories indicate a cross-disciplinary work--Phanerozoic, for example, refers not to rocks per se but about the evidence of life-- fossilised. Hence the conjunction of two disciplines  in the study of the non-living and the living. If the title becomes too ambiguous it will literally loss meaning to all but those who read the books the editor has perused. Not an efficient way to communicate with the reader in my view.
===''Introduction''===


:I had this very problem with the article on the [[Eastern Orthodox Church]]. I listed synonyms and made redirects and Robert is Your Mothers's Brother. [[User:Thomas Simmons|Thomas Simmons]] 17:07 19 April, 2007 (EPT)
* ''Geological ages in common use''. Could we have one or more references for the common use? --[[User:Nereo Preto|Nereo Preto]] 10:35, 9 June 2007 (CDT)


:Common use is just that. The point is a matter of clarification. Folks think of "The Jurassic Age" since they saw'' Jurassic Park''. ''Deep Impact'', another example of popular conception, there are these drastic catastrophes (redundant to make a point) and then everything changes.  Common use and thus common perception. --[[User:Thomas Simmons|Thomas Simmons]] 19:58, 9 June 2007 (CDT)
:Yes, got the point. Now, I believe what we are REALLY talking about are era/erathem boundaries here. At lower hierarchical levels, the relationship boundary-catastrophe becomes less and less true. I'll try to clarify this point better within the introduction. We'll need a [[mass extinction]] article sooner or later... This should be a solution also from the problem below. --[[User:Nereo Preto|Nereo Preto]] 03:29, 10 June 2007 (CDT)


::Did the redirects. If you input [[Classification of times]] or [[Geologic time scale]] you will get to [[Geologic ages of earth history]] - [[User:Thomas Simmons|Thomas Simmons]] 17:51 19 April, 2007 (EPT)
* ''refers to marked changes...'' at odds with ''boundaries are placed at completely arbitrary positions'' --[[User:Nereo Preto|Nereo Preto]] 10:35, 9 June 2007 (CDT)


I believe this does it for now. Thanks Thomas. --[[User:Nereo Preto|Nereo Preto]] 10:05, 20 April 2007 (CDT)
:It should be at odds. There were dinosaurs and then there weren't. Clear definitions in the common percpetion. The details get lost in the common perceptions. So, the first one is the common perception and the later is the scientific perception.--[[User:Thomas Simmons|Thomas Simmons]] 19:58, 9 June 2007 (CDT)
:I believe we can get rid of this contradiction without losing touch with common perception, see above. --[[User:Nereo Preto|Nereo Preto]] 03:29, 10 June 2007 (CDT)


== What is this article about? ==
===History===


I read more carefully the article and I got confused about its function. What is this article about?
===Definitions===
* If the article is about subdivisions of geologic time (without reference to absolute time, i.e., subdivisions which have a name regardless to their duration in millions of years), than we are talking about [[chronostratigraphy|chronostratigraphic units]]
* If the topic is the numbers, i.e., how many million years ago a certain event occurred, then we are talking about [[geochronometry]]
* If this article is intended at the description of geologic time, both in terms of its subdivisions, absolute ages and definition of subdivision boundaries (e.g.: the Cretaceous-Tertiary boundary ''may be'' defined  by the extinction of Dinosaurs), then the argument is the Geologic time scale.
* If instead the article is intended at a description of what happened through geologic time, then there is no name for it, but I suppose it would be something like "timeline of geologic time".
The reason I am so nitpicking -sorry about that- is the International Code of Stratigraphic Nomenclature (find it [http://www.stratigraphy.org/ here], under "stratigraphic guide"). The existance of such a code implies that some concepts of stratigraphy (as the first two of the list above) have an official name that cannot be changed. In other words, if we refer to, e.g., chronostratigraphic units and call them the Geological ages of the earth, every expert will stigmatise our article as wrong (and there will be no room for discussion).


The meaning of "Geologic time scale" is not encoded, but it is implicit in expert's use. Check out: Gradstein F.M., Ogg J.G. and Smith A.G., 2004, A Geologic Time Scale 2004, Cambridge University Press, Cambridge, UK. This is the latest work about the topic, and is at present used as "the Bible" among researchers and students. Brief description of the work [http://www.stratigraphy.org/scale04.pdf here].
===...===


I believe we must take a decision on which part, or concept(s), of stratigraphy we want to put in this article. Then it can be properly linked to other existing articles. Most important, we'll then be able to file it under a proper title.
===Schemata/eons/Phanerozoic===
--[[User:Nereo Preto|Nereo Preto]] 10:53, 20 April 2007 (CDT)
 
* Table: is someone able to put the ages on? (see ''Absolute ages in schemes'', above) --[[User:Nereo Preto|Nereo Preto]] 10:37, 9 June 2007 (CDT)
 
== Need to match article name with topic sentence ==
 
It seems to my uninformed mind that the first sentence "The geologic history of the earth..." is a better title than the current and cumbersome "Geologic ages of earth history". I leave it to the experts to decide what the focus of the article actually is/should be, but in any case the title and content should match and the title should be readily understood and snappy. [[User:Aleta Curry|Aleta Curry]] 18:54, 20 June 2008 (CDT)

Latest revision as of 13:05, 1 July 2008

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 Definition:  Measurement of the geologic history of the earth which can be broadly classified into two periods: the Precambrian supereon and the Phanerozoic eon. [d] [e]
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 Workgroup category:  Earth Sciences [Categories OK]
 Talk Archive:  1  English language variant:  British English

Absolute ages in schemes

Something like this, I mean...

Is anyone able to do something like this with schemes of time/rock subdivisions? It would be great. The alternative is to add a column to the tables with the absolute age of beginning for each subdivision, in Ma (million years ago). This latter solution would be, however, much less fancy. --Nereo Preto 13:19, 3 June 2007 (CDT)

P.S.: an example of one more column is in the thread above, green-colored. I don't like it much. --Nereo Preto 13:23, 3 June 2007 (CDT)

Note: the green example is now stored in /Archive 1 --Nereo Preto 02:25, 21 August 2007 (CDT)

How does this look. (The code is far form beautiful, it's not an easy thing to do this.) Derek Harkness 20:49, 9 June 2007 (CDT)

Erathem/Era System/Period Series/Epoch Stage/Age (Ma)
CenozoicNeogene Holocene  
0.0118
Pleistocene Upper/Late
0.126
Middle/Mid
0.781
Lower/Early
1.806
Pliocene Gelasian
2.588
Piacenzian
3.600
Zanclean
5.332
Miocene Messinian
7.246
Tortonian
1234
Serravallian
1234
Langhian
1234
Burdigalian
1234
Aquitanian
1234
 

It is a good start. Now if we could just get rid of borders and background in the last column... is there a help page or a handbook for wikitables? --Nereo Preto 03:21, 10 June 2007 (CDT)

List of perfectable things...

I am (slightly) passing this article throughout, to clean it up and make it look great. I open here a list of things that could be better. Add to list if you find problems, or strike the point if you find a solution!

Introduction

  • Geological ages in common use. Could we have one or more references for the common use? --Nereo Preto 10:35, 9 June 2007 (CDT)
Common use is just that. The point is a matter of clarification. Folks think of "The Jurassic Age" since they saw Jurassic Park. Deep Impact, another example of popular conception, there are these drastic catastrophes (redundant to make a point) and then everything changes. Common use and thus common perception. --Thomas Simmons 19:58, 9 June 2007 (CDT)
Yes, got the point. Now, I believe what we are REALLY talking about are era/erathem boundaries here. At lower hierarchical levels, the relationship boundary-catastrophe becomes less and less true. I'll try to clarify this point better within the introduction. We'll need a mass extinction article sooner or later... This should be a solution also from the problem below. --Nereo Preto 03:29, 10 June 2007 (CDT)
  • refers to marked changes... at odds with boundaries are placed at completely arbitrary positions --Nereo Preto 10:35, 9 June 2007 (CDT)
It should be at odds. There were dinosaurs and then there weren't. Clear definitions in the common percpetion. The details get lost in the common perceptions. So, the first one is the common perception and the later is the scientific perception.--Thomas Simmons 19:58, 9 June 2007 (CDT)
I believe we can get rid of this contradiction without losing touch with common perception, see above. --Nereo Preto 03:29, 10 June 2007 (CDT)

History

Definitions

...

Schemata/eons/Phanerozoic

  • Table: is someone able to put the ages on? (see Absolute ages in schemes, above) --Nereo Preto 10:37, 9 June 2007 (CDT)

Need to match article name with topic sentence

It seems to my uninformed mind that the first sentence "The geologic history of the earth..." is a better title than the current and cumbersome "Geologic ages of earth history". I leave it to the experts to decide what the focus of the article actually is/should be, but in any case the title and content should match and the title should be readily understood and snappy. Aleta Curry 18:54, 20 June 2008 (CDT)

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