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>
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!)
  <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>
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)
<tr>
 
  <td rowspan="3" style="border: 1px solid rgb(255,255,153);border-left: 20px solid rgb(255,255,153)">[[Pliocene]]
: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.
</td>
 
<td style="border: 1px solid rgb(255,255,153);border-left: 20px solid rgb(255,255,153)">[[Gelasian]] </td>
: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.
<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>
: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)
<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>
::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)
</tr>
 
<tr>
I believe this does it for now. Thanks Thomas. --[[User:Nereo Preto|Nereo Preto]] 10:05, 20 April 2007 (CDT)
  <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>
== What is this article about? ==
</tr>
 
<tr>
I read more carefully the article and I got confused about its function. What is this article about?
  <td rowspan="6" style="border: 1px solid rgb(255,255,0);border-left: 20px solid rgb(255,255,0)">[[Miocene]]
* 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]]
</td>
* If the topic is the numbers, i.e., how many million years ago a certain event occurred, then we are talking about [[geochronometry]]
<td style="border: 1px solid rgb(255,255,0);border-left: 20px solid rgb(255,255,0)">[[Messinian]] </td>
* 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.
<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>
* 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".
</tr>
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).
<tr>
 
  <td style="border: 1px solid rgb(255,255,0);border-left: 20px solid rgb(255,255,0)">[[Tortonian]] </td>
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].
  <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>
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.
<tr>
--[[User:Nereo Preto|Nereo Preto]] 10:53, 20 April 2007 (CDT)
  <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>
:We'll probably want to cover all four (and manybe more) aspects you described. However, are they all mutually exclusive. Could the article discuss more than one aspect. Even if they are exclusive, could they simply take independent sections within the whole article. Are not several of your devisions simply different views of the same item.
</tr>
 
<tr>
===What is the article about? (part 2)===
  <td style="border: 1px solid rgb(255,255,0);border-left: 20px solid rgb(255,255,0)">[[Langhian]] </td>
Lots of lists out there that purport to be about geologic ages. The lists are generated from and by many sources. Some of them do not coincide with the ICS for example. In other words, there is agreement and disagreement in that they are presented differently.
  <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>
So, on the one hand you want to present what is accepted or at least debated by those in the know and possibly avoid if not relegate nonsensical, unfounded or outdated to their proper categories. In the meantime, what is the reader looking for and what are our limitations?
<tr>
 
  <td style="border: 1px solid rgb(255,255,0);border-left: 20px solid rgb(255,255,0)">[[Burdigalian]] </td>
*Point One: Subdivisions of geologic time (relative to each other) are listed here with reference to absolute time in millions of years or fractions thereof (which does not detract from relevant disciplines in that it illustrates their overlap), and their names—which originate from a multitude of sources and for various reasons (e.g.  it was first studied in this place, there were these types of flora and fauna at that time as is evident from these fossils, etc.)—and the varying aspects of nomenclature (e.g. subdivisions which have a name regardless of their duration in millions of years). They can then be elucidated in the appropriate way here and then explained in detail in a linked article on, for example, [[chronostratigraphy|chronostratigraphic units]]. That said, assuming that I am reading the comments above correctly, it makes no sense to people who are living in the here and now (and measure time as humans are wont to do) to simply list the strata without reference to time—we will leave them with more questions than answers and put them off the topic. To that end, we put events into context. It is a daily thing that we are comfortable with. So, not at all sure why these strata (listed as they are by the ICS with their relative time spans by the ICS) would be listed otherwise. It is about the ages of the earth.
  <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>
*Point Two: The same can be said of [[geochronometry]]
<tr>
 
  <td style="border: 1px solid rgb(255,255,0);border-left: 20px solid rgb(255,255,0)">[[Aquitanian]] </td>
*Point Three: So yes, it is at first glance about geologic time scale and obviously there is relevance to stratigraphy and geochronometry which will be elucidated in those articles.
  <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>
*Point Four: As a “timeline of geologic time”, it serves to introduce a plethora of disciplines and as such is a portal to those disciplines. I can not imagine an in-depth discussion of this in one article, it would be huge and surely exceed the limitations of a normal article. It serves to delineate ages and their classification and broad but pertinent aspects.
<tr>
 
  <td colspan="5">&nbsp;</td>
Geological age here and its relation to stratigraphy is an expedient and certainly an accepted one. The article is an accounting of, an overview actually, the concept of the age of the earth and how it is delineated. Then you go into sedimentology, chronogeology, stratigraphy, relative and absolute time and so forth. If it is too limited, if there is no place for the hypernymic "supercategory", the generic and conceptual, it loses cultural and thus textual coherency and would simply exist in a semiotic vaccum. This then must serve as a primer. The issues or aspects are illuminated much like a map and does not have the capacity to go into great detail which must surely be explained elsewhere.
</tr></table>
 
I am not at all sure what the sentence "The meaning of "Geologic time scale" is not encoded, but it is implicit in expert's use." I say this since all language is encoded. Language is by definition a code. Symbols, both orthographic and phonetic, stand for other things.  In fact the more implicit it is, the more embedded the coding. Technical jargon is very much encoded coding. [[User:Thomas Simmons|Thomas Simmons]] 12:15 20 April, 2007 (EPT)
 
:OK, I thing I understood what you mean. You say "The article is an accounting of, an overview actually, the concept of the age of the earth and how it is delineated" and this is almost the concept of "Geologic time scale", plus some cultural excursions around it.
 
:You are also pushing for a writing style that can be understood by the beginner in Earth Sciences. I agree, this is a topic of wide interest and the article is an opportunity to offer scientific culture.
 
:What I'd like to do, however, is to keep language as close as possible to scientific correctness. So for example, for students of Earth Science there are two meanings for "age": one is the fundamental chronostratigraphic unit ([[Age (geology)]]), the other is the result an absolute datation, e.g., a radiometric datation, and is a number (e.g., the Induan ''age'' begun ca. 252 Ma, where "252 Ma" is a ''radiometric age''). So "Induan" is and age, but if we write or suggest that also "Triassic" is an age, this is an error: "Triassic" is a period. This was the reason I posted, in the beginning, some brief articles as [[Age (geology)]], so they could be used to build an article like this one.
 
:The average reader will not get the difference between ''age'' and ''period'' perhaps, but a reader with University instruction could notice it, and could dismiss the whole article as "uninformed". We must try to satisfy also that reader, I believe. --[[User:Nereo Preto|Nereo Preto]] 04:15, 21 April 2007 (CDT) (continues below inserted comments from [[User:Thomas Simmons|Thomas Simmons]])
 
::Could not agree more. At some point it becomes possible the beginning reader will want to pose informed questions and the language then becomes paramount. Disambiguation is also a step in the right direction as is the need to divest them of misconceptions. So, yes, beginner's language-->expert's language transitions would be very constructive. [[User:Thomas Simmons|Thomas Simmons]] 13:14 22 April, 2007 (EPT)
 
 
:About differences between sources. The rules in the International Guide of Stratigraphic Nomenclature MUST be obeyed. The way one defines, names, revises and eventually publishes, e.g., a chronostratigraphic unit is coded. If one's don't follow those rules, it cannot get published and his work is dismissed (this is the way things go at present). There are some residual "informal" chronostratigraphic units from past which are still in use, but they are becoming scarcer, and all specialists know they are going to be estinguished.
:The International Guide of Stratigraphic Nomenclature hasn't a definition fot Geologic time scale, so the use of this term is somehow less rigid. However, the authors of the latest time scale give this definition:
 
:The geologic time scale is the framework for deciphering the history of the Earth and has three components:
:* The international stratigraphic divisions and their correlation in the global rock record,
:* The means of measuring linear time or elapsed durations from the rock record, and
:* The methods of effectively joining the two scales.
:I believe this definition matches your view on this article quite well. I'll assume, as an editor, this is what you (we) are writing about.
:--[[User:Nereo Preto|Nereo Preto]] 04:15, 21 April 2007 (CDT)
 
::I am all for making this comply to national standards. Would not have it any other way. - [[User:Thomas Simmons|Thomas Simmons]] 13:33, 22 April, 2007 (EPT)
 
===What is the article about? (part 3)===
With regard to, "So "Induan" is and [sic] age, but if we write or suggest that also "Triassic" is an age, this is an error: "Triassic" is a period. This was the reason I posted, in the beginning, some brief articles as Age (geology), so they could be used to build an article like this one."
 
I take your point and to that end I have pursued the accepted nomenclature. However, the Triassic period is explicitly defined by ages and thus a determined period of time with margin of error factored in of course. But this is the connection that students make. If we need to elucidate this factor then so be it.  - [[User:Thomas Simmons|Thomas Simmons]] 13:40, 22 April, 2007 (EPT)
 
 
Regarding ''eonothem'' and ''erathem'', do we have a definition we can use? - [[User:Thomas Simmons|Thomas Simmons]] 14:14, 22 April, 2007 (EPT)
 
:Yes. Stratigraphers make a distinction between time and rocks deposited during that time. A interval of time is a [[geochronology|geochonologic unit]], while the body of rocks formed during that time is a [[chronostratigraphy|chronostratigraphic unit]]. The two categories of units have different names, as in this table:
 
{| class="wikitable" style="font-size:95%;" width="60%"  
! Chronostratigraphic units
! Geochronologic units
|- style="background:rgb(225,225,175)"
|
* [[Eonothem]]
** [[Erathem]]
*** [[System (geology)|System]]
**** [[Series (Geology|Series]]
***** [[Stage (geology)|Stage]]
****** Substage
|
* [[Eon]]
** [[Era (geology)|Era]]
*** [[Period (geology)|Period]]
**** [[Epoch (geology)|Epoch]]
***** [[Age (geology)|Age]]
****** Subage
|}
 
:Thus, the [[Mesozoic]] [[erathem]] is the body of rocks formed during the [[Mesozoic]] [[era (geology)|era]]. --[[User:Nereo Preto|Nereo Preto]] 03:35, 22 April 2007 (CDT)


A; That is a cool table. Looks great. Elucidates an important distinction. Shall we put it in?
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)
B: The words themselves are not in any dictionary I can find so I am guessing it is Latin? Have not looked it up in a Latin dictionary.- [[User:Thomas Simmons|Thomas Simmons]] 22:22, 22 April, 2007 (EPT)


== Tables of time/rock units ==
== List of perfectable things... ==


I copied tables of the time/rock units from [[chronostratigraphy]], in order to avoid the spelled lists of Periods, Epochs, Ages... it seems to me more readable.
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!


DO NOT CHANGE THE FILLING COLORS! Those colors are codified and, though the exact RGB values may change, there is a >50 year consensus on facts as, e.g., the Cretaceous is green and the Jurassic is blue. Geologists are strange people sometimes, I must admit...
===''Introduction''===
I know some writings are invisible; I suppose we could change the color of text, but how to do it? --[[User:Nereo Preto|Nereo Preto]] 15:08, 21 April 2007 (CDT)


I'd also like to move all absolute ages into the tables. It can be easely done by adding a column with the absolute age of the stage/age lower boundary, but it would be more fancy to have the numbers right on the boundaries, perhaps outside the table itself. Is it technically possible? --[[User:Nereo Preto|Nereo Preto]] 15:36, 21 April 2007 (CDT)
* ''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)


:Colour--NO ARGUMENT FROM ME! : ) If they establish a standard that is acepted then I am a big one for coherency. The text colour is a problem though. Archean and Eoarchean are unreadable, most entries entries from Statherian are difficult, Permian and half of the epoch and stages are difficult to unreadable.
* ''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)


:Absolute ages--would be nice. I have had mixed sucess with these tables. Do we have a manual? I'd practice if I had somewhere to do it and a list of possible colour codes. [[User:Thomas Simmons|Thomas Simmons]] 13:27, 22 April, 2007 (EPT)
: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)


===History===


::Text colour--Just tried various permutations in a sandbox with no luck. I seem to be able to change everything including background colour and table configuration but not the text colour. - [[User:Thomas Simmons|Thomas Simmons]] 14:00, 22 April, 2007 (EPT)
===Definitions===


May I suggest using border colors for the table rather than background colors. This will maintain the white background behind the text and so prevent reading problems e.g. A very crude example (needs some polishing)
===...===


<table class="wikitable" border="3" style="font-size:95%;">
===Schemata/eons/Phanerozoic===
 
<tr>
<th> [[Eon]]
</th><th> [[Erathem]]/[[Era]]
</th><th> [[System (geology)|System]]/[[Period (geology)|Period]]
 
</th></tr>
<tr>
<td rowspan="4" style="border:10px solid rgb(240,2,127)"> [[Archean]]
</td><td style="border:10px solid rgb(249,155,197)"> [[Neoarchean]]
 
</td><td style="border:10px solid rgb(249,155,197)">&nbsp;
</td></tr>
<tr>
<td style="border:10px solid rgb(234,102,177)"> [[Mesoarchean]]
</td><td style="border:10px solid rgb(234,102,177)">&nbsp;
</td></tr>
<tr>
<td style="border:10px solid rgb(244,68,159)"> [[Paleoarchean]]
</td><td style="border:10px solid rgb(244,68,159)">&nbsp;
</td></tr>
<tr>
<td style="border:10px solid rgb(218,2,127)"> [[Eoarchean]]


</td><td style="border:10px solid rgb(218,2,127)">&nbsp;
* 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)
</td></tr></table>
Remember a very high percentage of men have some degree of color blindness. Particularly blue/green. We should be very carefull when placing text on a colored background or when using colored text. [[User:Derek Harkness|Derek Harkness]] 21:23, 21 April 2007 (CDT)


:This makes it. Thanks Derek! --[[User:Nereo Preto|Nereo Preto]] 03:37, 22 April 2007 (CDT)
== Need to match article name with topic sentence ==


::Definitely. Ta Derek. Good point. Looks great. - [[User:Thomas Simmons|Thomas Simmons]] 22, 22 April, 2007 (EPT)
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)

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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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