Talk:Geologic time scale/Archive 1

Old posts

I'm pretty sure that there is an article on Radiometric dating under some name variant or other, but I can't seem to locate it. For the time being, I'll write another and I (or, better, somebody who actually knows about the subject) can clean the multiple articles up.

You probably mean the Radiocarbon dating page. There probably should be a broader page that also deals with dating using other radio-isotopes. --Eob. I thought there was a more general article as well -- no matter djk.

Is there a specific reason why this is an ASCII table instead of a HTML one?

Posts above added to this page by Hagedis (Talk) at 23:04, 13 December 2001 (UTC)

Because that's the way whoever put it in formatted it. I left it that way when I worked it over because I'm a firm believer that the simplest approach to most things that works fairly well is usually the best one. --djk —Preceding unsigned comment added by 216.192.71.140 (talk • contribs) 14:20, 8 July 2002 (UTC)

Appearance of Flowering Plants

Angiosperms first appeared in the Jurassic, not the Cretaceous. I have slightly altered the mention of them in the column so that it says they "proliferate"d in the Cretaceous, not they "appear"ed. Ventifact 05:01, 15 May 2006 (UTC)Ventifact

Age versus Stage

I noticed that throughout many articles in Wikipedia, the smallest subdivision of geologic time is referred to as a Stage. While I have used the same nomenclature in my own articles in order to be consistent with the project, I wanted to bring up the fact that this is technically not correct. Stage is a stratigraphic term referring to a bed of rock that corresponds to what in the geologic time scale is referred to as an Age. An Age is the "geochronologic" equivalent of a Stage. Thus, an age is the proper term for the smallest division of geologic time. Though, you can have sub-ages if necessary.

I am basing this on The International Stratigraphic Guide, Second Edition, 1994, The Geological Society of America and The International Union of Geological Sciences. Age is defined on page 106, and Stage is defined on page 136. Also, section 9.C.2 and Table 3 (pages 78 and 79) deal with the stratigraphic and time scale subdivisions and how they relate to one another.

I would like to get other people's input. I believe that all occurrences of Stage in Wikipedia that refer to time scale should be changed to Age. What do other people think?

---

Likewise, "Late" and "upper", and "early" and "lower" are not interchangeable - Late and Early are time terms, Upper and Lower refer to rocks. You should not talk about "Late Cretaceous chalk" for example, nor about "upper Cretaceous events". Generally, in this article about geologic time, "upper" and "lower" have no place, except in terms of explaning the difference between them and the time terms. --Geologyguy 15:12, 9 April 2006 (UTC)

Actually, you can talk about "late Cretaceous chalk." It's chalk that was deposited during the late Cretaceous. Rocks can be described by upper/lower or by late/early.

You can, and many do. But it is not correct. "Early" and "late" are time terms. From the Glossary of Geology: early "applied to the name of a geologic time unit (era, period, epoch) to indicate relative time designation, and corresponds to lower as applied to the name of the equivalent time-stratigraphic unit; e.g. rocks of a Lower Jurassic batholith were intruded in Early Jurassic time." So, strictly speaking, chalk that was deposited during the Late Cretaceous must be Upper Cretaceous chalk. You could talk about Upper Cretaceous chalk and everyone would know it was deposited in Late Cretaceous time. Or you could talk about chalk of Late Cretaceous age and everyone would know it was from the upper part of the Cretaceous System (system is the rock equivalent of period, the time term). I know it is nit-picky, but this is the correct formal usage, according to the Glossary of Geology as well as the USGS Suggestions to Authors. Also, the adjectives - early, middle, late, lower, middle, upper, are capitalized when the division is formal, as with Upper and Lower (or Late and Early) Cretaceous, but upper Paleozoic and early Eocene. There is a good discussion here: [1]. --Geologyguy 22:03, 15 May 2006 (UTC)

Palaeozoic / Paleozoic

I'm noticing that the page for the era is Palaeozoic though most of the links trying to reach that page are spelled "Paleozoic". Is one more correct than the other? -- RjLesch.

As far as I can tell, both spellings are acceptable. Without the extra a is more common -- especially in American English -- but the original link was set up with the other spelling. Same story on Paleogene

Yes, Palaeozoic, Palaeogene, and Palaeontology are all UK spellings, while Paleozoic, Paleogene, and Paleontology are U.S. spellings. But, which should be used here? --Lenn 17:56, Jun 23, 2005 (UTC)

Wikipedia already has guidelines set up to answer that question.

First Fish

6/15/02 I removed "first fish" from the Ordovician because in the past five years, a number of (probable) chordates have turned up in the Lower Cambrian of China. Two of them are almost certainly "fish". No intent to start a war. If anyone wants the first fish back in the Ordovician, put them back and I promise to leave them alone. djk

HTML table

Note that the improvement that converted the table to HTML moved the date of the end of the period to line up with the name and description whereas with the "primitive" ascii, it was (as it should be) lined up with the line delineating the end of one period and the start of the next. If anyone can think of any easy way to put the dates back where they belong, please do so. (... yet more proof tht Ned Ludd and his followers had a point).

--

I think the HTML table is great, but my opinion is that the time scale should be reversed, with the oldest time at the top and the most recent at the bottom. It makes more sense to read the history of geology and evolution in the order in which it happened, rather than backwards. -Monz (talk) 18:17, 23 November 2008 (UTC)

i disagree. the natural sequence of rock layers is most recent at the top, older underneath. and placing oldest at the top puts a lot of historically empty time where it can't be ignored. 67.142.161.21 (talk) 01:44, 10 February 2009 (UTC)

Neophyte question

I'm a neophyte just trying to learn the Geologic Time Scale for the first time (however noticed all the different presentations),and so comment (question, actually)with trepidation. I don't understand what is being said in 5) near the end of the article: "In common usage the Tertiary-Quaternary and Paleogene-Neogene-Quaternary Periods are treated as equivalents to the Mesozoic and Paleozoic Periods". Are you saying in part that the Mesozoic and Paleozoic Ages are, in common usage, sometimes regarded/referred to as Periods? I'm also not sure what you mean by "treated as equivalents"; strictly on word-meaning, I would take this to mean that the Tertiary-Quaternary covers the same time period as the Mesozoic, and the Paleogene-Neogene-Quaternary as the Paleozoic, but its obvious from the Time Scale you don't mean that. I think probably it's meant that these are placed on the same level (in this case, figuratively in the same column) or given the same weight, etc. I would really appreciate some clarification on this, because its the presentation of the origin, variation, and use of the Geologic Time Scale terms here and in other related articles, that I find so valuable.

Is the Proterozoic subdivision verified? This page says that it includes

• Hadean
• Archean
• Paleoproterozoic
• Mesoproterozoic
• Neoproterozoic

However other sources list

• Hadean
• Archean
• Proterozoic
  • Paleoproterozoic
  • Mesoproterozoic
  • Neoproterozoic

Help, anyone? - fagan

---

Why are the epochs in the cretaceous and before not shown? should be added. I tried to do so, but I can't get the table formatting to work. Can someone else do this? Amblypygi 16:37, 17 Apr 2004 (UTC)

---

The Ediacaran has been upgraded to a bonafide geologic period. http://news.bbc.co.uk/2/hi/science/nature/3721481.stm Therefore, it will have to be squeezed in between the Cambrian and Neoproterozoic.TimothyPilgrim 15:35, May 20, 2004 (UTC)

Actually the Neoproterozoic should be an Era (not a period) and one which contains the Ediacaran period. Likewise, Proterozoic, Archean and Hadean are technically eons, not eras. Essentially the whole botton part of that chart needs to be shifted. I suggest refering to the Geowhen database or the ICS list (both linked at the bottom of the article) to see how it ought to be set up. Dragons flight 17:12, May 21, 2004 (UTC)

Boundaries

(William M. Connolley 19:11, 22 Sep 2004 (UTC)) I notice that the period boundaries aren't defined in the table. To me this seems odd. For example, the pleistocene/holocene boundary is the end of the last ice age, which is important. Could this be incoporrated into the table?

Technically the Pleistocene/Holocene boundary is 10000 Carbon-14 years BP, and I'm not sure many of the other boundaries are particularly informative either. The end of the Cretaceous, Jurassic, Triassic, Permian, Ordovician, and Silurian are all exinction events. The Devonian boundary is slightly after a major extinction. The end of the Cambrian is the onset of an adaptive radiation, and the ends of the Carboniferous and Paleogene are basically arbitrary.

One probably could list all of the extinctions, but I'm not sure that is all that useful or at all that easy to incorporate. I did however add end of ice age to the events of the Holocene.

Dragons flight 06:25, Sep 23, 2004 (UTC)

Note 5

I have a degree in geology, and I'm not sure what note 5 is getting at. Is it suggesting that "Tertiary" (or "Neogene and Paleogene") and "Quaternary" are sometimes regarded as being at the same level as "Mesozoic" and "Paleozoic"? If someone can't explain this, we should probably remove that note. Gwimpey 20:59, Nov 16, 2004 (UTC)

Since some time the term "Tertiary" is out of use and there are two periods which replace the Tertiary: "Neogene and Paleogene". Perhaps the note should point in that direction. Surely they are not in the same level as "Mesozoic". --chd 10:05, 19 Nov 2004 (UTC)

Mnemonic for the Geological Timescale

When I first started studying geology, I found it difficult to remember the order of the periods. The following mnemonic [for the Cambrian to Holocene] helped. It is modified from one passed down through the generations of students at my college, so I'm afraid I can't acknowledge the original source: Camels Ordinarily Sit Down Carefully, Perhaps Their Joints Creak [Probably Even Old Mules Plod Peacefully Home]

Discussion item - nav boxes

Cross posting for those who might not otherwise notice, to point out the discussion item I added at Wikipedia_talk:WikiProject_Geologic_Timescale#Top_navigational_templates. —Mike 09:19, Jan 27, 2005 (UTC)

Periods?

I am working on sr: timeline scales and calendars. It seems that this page was changed: where are Tertiary and Quaternary? As I am not geologist (or paleologist or...), I am confused. What is Quaternary and what is Neogene? --Millosh 08:40, 20 Feb 2005 (UTC)

Effective with the 2004 time scale, the International Commission on Stratigraphy has removed "Tertiary" and "Quaternary" from the set of stratigraphic terms recommended for formal usage. Instead the usage of "Neogene" and "Paleogene" Periods, as shown on the page, is reccomended.

Dragons flight 09:08, Feb 20, 2005 (UTC)

Thanks for quick response. I'll remove Tertiary and Quaternary from sr:, too. (I mean from timeline scales.) --Millosh 10:23, 20 Feb 2005 (UTC)

The ICS has now (as of their 2007 time scale) proposed adding back Quaternary, which undoes some of the mess they made by extending the Neogene to the present, creating confusion with the previous definition of Neogene, which was wholly in the Tertiary. See http://www.stratigraphy.org/gssp.htm -- 68.45.104.173 10:01, 5 November 2007 (UTC)

JCHYSK's Hadean

JCHYSK recently added 4 subdivisions to the Hadean. I am inclined to revert this on two grounds a) they are not part of the formal ICS nomenclature (even though they are admittedly well established), and b) I just think having a compressed Hadean looked better. It is not like very many people are going to come along and care about the divisions of the Hadean. This is basically the same reason for not using all the upper and lower epochs of the Mesozoic and Paleozoic, it just gets messy, and links on this page can provide additional detail for those that actually need it.

Anyway, that's my feelings on the matter, but before I reverted it, I thought it is worth posting here for comment. Dragons flight 13:05, Mar 4, 2005 (UTC)

As for me, I would prefer to actually have Cryptic, Basin Groups, Nectarian and Lower Imbrian on the chart. As for the appearance, a border (or better yet, an outline, CSS-speaking) could fill the bill of not cluttering the chart:

• different consideration (official/not official)
• different styling (background color/border color)
  

Reply to David Latapie 00:35, 22 May 2006 (UTC)

Removal of Hadean from main chart

The chart dosn't include Precambrian, Tertiary and Quaternary. These divisions, like Hadean, are not official ICS nomenclature, but are (still) in widespread use with some Geologists. Addind these divisions would seriously clutter the chart and I think everyone would agree that it would be a mistake. By that logic, Hadean should be removed. The inclusion of Hadean is confusing: The way the current chart stands, a naive reader would believe that the Archaean and Eoarchean begin 3800 mya, whereas actually they have no lower boundary according to the ICS. Also, it seems sort of silly to have an entire chart except one entry fit with ICS nomenclature. I think that Hadean should be reslihed to being a footnote. Comments? -Casito⇝Talk 19:54, 25 Apr 2005 (UTC)

I am opposed to this. I don't think the Hadean contributes to clutter the way the other cited terms would. You are correct that it not currently part of the formal nomenclature, but it is pretty much the de facto term for the earliest part of Earth's history. Potentially more important, the Precambrian Subcommission of the ICS is calling for its ratification as formal division, with voting on this issue to start later this year. The biggest hold up has been that people are having a hard time defining where the beginning of the Archean ought to be. Some prefer using a 3800 Ma GSSA (or some similar time), but others want to define a GSSP associated with the earliest known crustal rocks. So while they argue about this, the base of the Archean is left hanging, though I don't know of anyone who actually wants the Archean to extend all the way back to the formation of Earth. So basically, I think it makes sense to leave the Hadean in, following common usage, while we wait for the ICS to get their act together and decide how exactly they want to define the earliest part of Earth's history, which will probably mean including a Hadean anyway. Dragons flight 20:27, Apr 25, 2005 (UTC)

Okay. Let's leave it in. Once ICS makes up their mind, we should be sure to update the chart, and change its color once the USGS adopts one. Thanks. -Casito⇝Talk 20:33, 25 Apr 2005 (UTC)

The ICS has made up its mind, and the Quaternary has been reinstated (with a changed base just to keep you confuzzled). See the latest version of the ICS chart. Orcoteuthis (talk) 21:37, 19 November 2009 (UTC)

remember there are quite a lot of textbooks, or "popular" accounts such as "Basin and Range", which may use older terminology. retaining even outmoded or superseded terms in a concordance, or a section on updated nomenclature, would be useful. Macevoy (talk) 01:49, 10 February 2009 (UTC)

Thanks for leaving it in - I agree - it's also used in present published academic literature, such as that with the ancient detrital zircons in the Jack Hills of Australia. Awickert (talk) 02:07, 10 February 2009 (UTC)

USGS

How can it be said that the USGS doesn't recognize the Hadean when it is a term both in their Thesaurus and a search term in GEOLEX? --Bejnar 03:39, 17 January 2007 (UTC)

Carboniferous

Apart from the Gzelian and Kasimovian (in the Late Pensylvanian), the Early Middle and Late divisions of the Mississipian and Pensylvanian match exactly with the well-known epoch names of Tournaisian, Visean, etc. For this reason, I feel that this should be allowed to stand, rather than reverting back to the earlier version. Ok i know that Gradstein and Ogg 2004 use Early Middle and Late for each of the Carbooniferous subperiods, but this seems completely redudant, and the Carboniferous epoch names are well established. M Alan Kazlev 09:18, 8 May 2005 (UTC)

We say in the header that the timescale follows ICS conventions, and I think it is problematic to start deviating from that, since there are any number of places where one could. (The single exception to ICS conventions at present is the Hadean which is footnoted and follows the discussion given above (i.e. noting that the Hadean is a sort of preconvention convention)) Also, while I agree that the names are well-established, I would question whether they are well-established as "epochs". Harland 1989 used them that way, but both the GSA and ICS have prepared time scales where they are listed as stages, not epochs. I agree with you that it is somewhat awkwardly redundant, but that strikes me as the ICS's problem. In my opinion, consistency is more important than trying to overcome what may be viewed as the failings of the ICS nomenclature. Dragons flight 16:44, May 8, 2005 (UTC)

Continents vs. Critters

It would make sense to separate columns on the table for geology and biology. Show what was going on with the various continents and supercontinents - Rodinia .. Pannotia .. Pangea .. etc in one column with biological evolution over to the right. It is difficult to read as it is. Quinobi 08:49, 8 Jun 2005 (UTC)

But what about climate etc? Or we could have geology, climate etc in one column, and the evolution of life in the other. But would there be enough space available, considering how crowded the table is already? M Alan Kazlev 04:02, 29 September 2005 (UTC)

Congratulations

This page is "quite accurate" and "consistent with the most recent data".

Wikipedia:Wikipedia_Signpost/2005-07-04/In_the_news

Dragons flight 16:14, July 11, 2005 (UTC)

Table of geologic time - recent series/epochs

I like the way the table of geologic time shows the calculated error values for the column giving the start times, but is there any way to change from "millions of years ago" for the earlier times, to thousands of years for the Holocene Epoch; and maybe also from milions to billions for the earliest times (unless many people still use the outdated milion million for a billion)? ie. The Holocene started 11,430 years ago, +/- 130 years? Since it is only one entry that might confuse people with a start date of 0.011430 million years ago, maybe leave it that way in the table, and add a footnote giving this value in thousands of years? 194.200.237.219 11:21, 17 October 2005 (UTC)

Table footnotes

I understand that the footnote system is largely used for linking passages to their relevant references, but is there any reason it should not be used for the numbered footnotes within the Table of geologic time? Lusanaherandraton 06:45, 18 November 2005 (UTC)

Great work!

BBC links to you from their Prehistoric life site. Congratulations! — Knowledge Seeker দ 05:34, 7 April 2006 (UTC)

Early/Late vs Lower/Upper

I added an explanation in the Terminology section differentiating between these words' uses. Reference, Glossary of Geology: "lower - pertaining to rocks or strata that are normally below those of later formations of the same subdivision of rocks. The adjective is applied to the name of a time-stratigraphic unit (system, series, stage - see also comment by someone near the top of this page - system, series, and stage are rock equivalents of the time terms period, epoch, and age, respectively) to indicate position in the geologic column and corresponds to early as applied to the name of the equivalent geologic-time unit; e.g. rocks of the Lower Jurassic System were formed during the Early Jurassic Period. The initial letter of the term is capitalized to indicate a formal subdivision and is lowercased to indicate an informal subdivision." I can't find the most recent edition of the USGS Suggestions to Authors, but I'm sure this usage is followed there too, and my copy of the International Commission on Stratigraphy time scale does not use the words Lower or Upper anywhere, but I'd leave them on the graphical column on this page because many time scales do include both. I've made appropriate changes on some of the pages for periods and stages (most of Mesozoic, working on Paleozoic). --Geologyguy 14:36, 30 April 2006 (UTC)

Radiometric Dating = a measurement tool, NOT a piece of evidence.

Was: ...Current radiometric dating evidence indicates an age of the Earth of about 4570 million years old...

Should Be: ...Current radiometric dating indicates an...

All measurements are made by methods, tools and standards. All methods, tools and standards are characterized by uncertainties and assumptions. It is merely a measurement, not necessarily a piece of evidence, especially not in the interpretive context here. In fact, it is a measurement, further "post-processed" via mathematical models. The end result is a rough calculation. A calculated result may be evidence of a method, but the method is not evidence of its calculated result.

Presence of carbon left somewhere, for example, can be a piece of evidence. A measured amount is not evidence, it is a measurement, already subject to the weaknesses of uncertainties and assumptions. The interpretation of said measurement, via post-processing or other is even less a piece of evidence. That many such intepretations agree is also not evidence. It is massaged data.

For instance, in the fields of mechanical engineering, there is the ASTM (American Society for Testing and Materials). These are field established means to get all communications on the same page.

Perhaps this discussion of what is acceptably coined "evidence" is a philosophical discussion in itself.

In my PhD work in failure of continuum mechanics medium at Purdue University, the overriding philosophy was that if you do not understand the underlying assumptions in your models, you are not ready to present. If you do, you will be overwhelmed with humility at the real obsurdity with what we deal. In other words, if you do not understand the assumptions, forget about defending a thesis. Your candidacy should never have occurred.

Hopefully, Wikipedia can adhere to high standards of academic integrity such as this and not be just another stream of journalistic (ie drop-out from the pure or applied sciences) garbage where loaded words are carelessly applied.

(Above unsigned five edits by anon. 192.35.35.34)

No. Radiometric dating is not a tool, it is a technique or batch of different techniques that use a variety of physical tools (scintillation counters, mass spectrometers ... etc) to gather the raw data which is the evidence. Your piece of carbon left somewhere is not in itself evidence. The evidence are the data which we derive from that piece of carbon with our scientific techniques and tools. The measurements (data) made with the tools using the techniques of radiometric dating are the evidence.

An analogy would be the our understanding of the composition of stellar atmospheres. We gather light from the star and using the tools of spectrography we gather the data that is the evidence for our understanding of the star atmosphere.

For a different analogy. A geologist uses a tool, the Brunton compass, to measure the attitude of strata in a complex area. the dip and strike data are ploted and analysed to decipher the structure of the region. The dip and strike measurements are the evidence supporting the interpreted structure.

The tool or technique used is not the evidence. The evidence is the data aquired or measured with the tools.

The data gathered by the tools of the radiometric dating techniques are the evidence for the ages of rocks. A single piece of data (datum point) doesn't suffice, it must be backed up by other data collected by the study.

Radiometric dating techniques and the tools they utilise have been in use for nearly a century and have been (and continue to be) fine tuned and refined to make sure the data collected is adequate to use as the evidence in a variety of academic and commercial applications.

Now, your bragging about your PhD is irrelevant here, in fact it simply brings to mind the old saw: Phd = piled higher and deeper. And if you don't know what is piled, then you must be out of the loop. Cheers, Vsmith 23:17, 15 May 2006 (UTC)

Yes. The PhD itself is irrelevant (as are the qualifications of anybody who's contributed anything to any field); and neither is it bragging. Hopefully, you are not implying that the philosophy of high academic integrity is irrelevant. Though these techniques and tools (and we would add the largepart of the collection of datapoints) have been in use for nearly a century and fine tuned, their basic assumptions remain common and the same. If the assumptions are found at a loss, the entire deck of cards collapses; and the game is over. That is what a PhD means that one should understand. Others usually don't. And if you don't know what the danger is with assumptions are, then being in the loop is the least of your concerns. Regards, User:192.35.35.34, 17 May 2006 (UTC)

So, if you are aware of some basic flaw in the assumptions that radiometric dating is based on, then I'd suggest discussing it on the talk page of that article and not here. Now, if the conflict is simply between the assumptions behind the science and the assumptions that your religious views are based on -- discussion over. Cheers, Vsmith 01:56, 18 May 2006 (UTC)

Toot toot! I find the reasons behind the one-word change to this article filled with rhetoric. If I measure PhD Pat's editing using current "methods" and "standards," the most accurate terminology would be "recent radiometric dating" or "prevalent radiometric dating," rather than his "corrected" "current radiometric dating." The term "current" assumes immediately present technique and technology, which is incorrect.

merge fossils article in?

there is a shorter article called Fossils and the geological timescale, it should probably be merged in with this better more complete article, but i'm not sure how to do it.

Made that a simple redirect here as the info there was rather sketchy and much more is already here. Vsmith 03:01, 24 May 2006 (UTC)

Inaccuracy of statement "no way to determine time scale represented"

While they didn't have a good way to determine the time scale represented, it is incorrect to say they had no way at all. In fact, early geologists had good information by which they knew that the time scales was in hundreds of millions of years even though they could not be very precise about anything. Greeneto 16:33, 2 June 2006 (UTC)

Timothy Clemans has stated arbitrarily that my point here is incorrect, but without any explanation whatsoever. My statement is correct, and I was hoping for someone more knowledgeable to address the specific issue (which Timothy unfortunately just ignored) and reword the sentence correctly. Since now even the fact that the sentence itself is incorrect (which is what the tag was for the purpose of flagging) is being removed, looks like I'll reword the sentence in a vague manner myself. I hope someone will come along soon who can give it a little more detailed explanation. (Greeneto 01:03, 11 June 2006 (UTC))

Hello - what exactly is the sentence needing rewording? As near as I can tell the changes Greeneto made look good; indeed, the early geologists did have ways to determine absolute age, but (as you say) they were not very accurate. It seems to me that this history part of the article should focus most on the relative time scale, which was what the British geols developed well; the references to absolute age are appropriate but discussion in depth could go in the article Age of the Earth. Just my 2 cents --Geologyguy 01:35, 11 June 2006 (UTC)

History of the time scale

I created a comparison of Lyell's 1833 scale with the modern scale here. I arbitrarily cut it off 650 mya, since Lyell didn't demarcate boundaries past what is today the Phanerozoic, but I think it makes for an interesting visual comparison. Anyone object to my adding the timelines to "History of the time scale"? Or any suggestions for improvement? -- bcasterline • talk 04:41, 26 June 2006 (UTC)

Holocene timescale

One of the footnotes needs more context and corrections:

• "The start time for the Holocene epoch is here given as 11,430 years ago ± 130 years (that is, between 9560 B.C. and 9300 B.C.). For further discussion of the dating of this epoch, see Holocene."

Firstly, as this is the time period closest to today's time, when people calculate what "11,430 years ago" means, they need to know when this calculation was made? 1950? 1970? 2004? Does anyone know? Ah. Looking at footnote 2, I see these values are based on the International Commission on Stratigraphy 2004 time scale - so 2004 was a good guess on my part! :-)

Secondly, calculating "9560 B.C. and 9300 B.C." from "11,430 years ago ± 130 years" from 2004, seems wrong. Shouldn't it be 9426 BC ± 130 years? That is 9556 B.C. to 9296 B.C. as the range. The range quoted in the article assumes the dating was done in the year 2000. What is going on here? Was the original table based on the International Commission on Stratigraphy 2000 time scale (if such a thing exists)? Carcharoth 00:40, 2 July 2006 (UTC)

Geological convention is that "years ago" and "years before present" are with respect to 1950. Hence 11,430 years ago should be 9,480 BC. Also, one shouldn't carry more than one digits than make sense with the error estimate. Hence 151,123 +/- 1200 should always be reported as 151,100, etc. In this case the correct numbers are 9610 BC to 9350 BC. Dragons flight 00:53, 2 July 2006 (UTC)

Ah. 1950 is the convention. Thanks. I never knew that. Has all this been added to the article? Carcharoth

PS. After puzzling over your 'error estimate' bit, I think I see where we've misunderstood each other. When I said 9426 BC ± 130, I was presenting a number generated from a calculation. ie. 2004 A.D. - (11,430 ± 130) = 9426 BC ± 130. I didn't mean to imply that the error of ± 130 was in the figure of 9426 BC, which is what I think prompted your bit about error estimates. I was merely placing the error bar around a point in time 11,430 years before 2004 AD. Hope that clears up any misunderstanding. Carcharoth 01:25, 2 July 2006 (UTC)

Hmm. Investigating further, I found an HTML version of a PDF document from the International Commission on Stratigraphy. That document gives the Holocene boundary as "0.0118 Mya", which differs by four from the "0.0114" figure above, which makes sense if that document was published in 2004, but our figure refers to a document published in 2000 (it would account for the 4-year time difference). So it seems our figures are internally consistent, but the discrepancy with the latest charts need to be corrected or explained. Either we need to increase this figure by one every year, like the ICS seem to do, or we need to make clear when the definition/measurement was publiched/made. Carcharoth 00:51, 2 July 2006 (UTC)

0.0118 Mya would be 11,800 years ago, a difference of 400 years not 4 years. Dragons flight 00:53, 2 July 2006 (UTC)

OOPS!! :-) You are quite right. I must avoid doing mental calculations late at night... I assume that the article needs updating if this is indeed a new figure used by the ICS? Carcharoth 01:02, 2 July 2006 (UTC)

I've checked again, and the ICS chart definitely says "0.0118" instead of "0.0114". I also found the chart at this link, which should be authoritative enough. I think the value for Holocene needs updating here and at Holocene. I'm also uncertain as to where the error values for the more recent epochs are coming from. They aren't on any of the charts I've been able to access online. Carcharoth 01:19, 2 July 2006 (UTC)

It comes from the definition of the Holocene as starting exactly 10000 radiocarbon years before present. Assuming your reference is authoritative, it would appear that this informal definition has been supplanted by one referencing the Younger Dryas event. Dragons flight 01:55, 2 July 2006 (UTC)

The authors of A Geologic Time Scale 2004 suggest that the ICS is trying to move away from dating chronometrically even in the Precambrian, so it makes sense that they would avoid a chronometric definition for the base of the Holocene and rely on a climatic event instead. -- bcasterline • talk 03:03, 2 July 2006 (UTC)

I also wonder about the Neogene error values. The footnote says the values come from the 2004 ICS scale, but that stratigraphy.org chart is a recreation of the published chart, and both provide ± 0.00. -- bcasterline • talk 03:03, 2 July 2006 (UTC)

Well, as long as you two can sort something out, that would be great. I don't know enough about this sort of thing, but I do like to point out stuff like this when I spot it. The Neogene error values almost certainly come from an earlier edit that wasn't referenced. It may require someone to dig back through the page history to find out, or just quietly replace it with the latest, most up-to-date information, unless someone wants to start an article tracing the evolution of the international data and definitions of the geologic timescales and how the values varied over time until the final values were settled! Carcharoth 12:55, 2 July 2006 (UTC)

What does the * mean in the table?

I'm noticing that in the table of timeperiods, the number in the "start" column has a superscripted ^* in almost every row down to Ediacaran. I'd normally expect that to mean there's a footnote for those, but I can't find any footnote marked with a star so I have no idea what it means. Also, while I'm on the subject, the start date for the Ediacaran is messed up; it reads "630 +5/-30", which I also don't know the meaning of. Bryan 03:34, 28 August 2006 (UTC)

As explained in footnote 2 7, * means a GSSP exists for that boundary. 630 +5/-30 means the prefered date is 630 Ma, but the possible range is 600-635 (ie. asymmetric error range). Dragons flight 03:38, 28 August 2006 (UTC)

How do they know how old the rock layer is?

The answer might be in the text, but I can't seem to find it. Anyway, how do they know how old the rock layer is? I ask this because creationists argue that the rock layers are dated by circular reasoning. They say scientists state the rock layer is as old as the fossils located in that layer. But then they state that the fossils are dated depending on the layer it is found it, hence the circular reasoning. Also they state that the layer can't be dated by how deep it is found because the mineral deposits could have formed quickly in a short period of time. It's an interesting catch-22, so I'm curious.

Is there a method to date the layer using some absolute dating method? Inforazer 15:24, 25 September 2006 (UTC)

This is a standard creationist claim, that like most creationist claims has little or no basis. The geologic column (that, is the releative age of strata and fossils) was determined prior to the theory of evolution by basic geological techniques such as comparisons between strata types and order of the strata. Absolute times are generally then derived by radiometric dating. The only thing remotely close to the creationist claim is that sometimes a fossil in location A may be dated by some method (such as radiometric dating) and then when the same type of fossil shows up in location B we can get a rough idea how old the B location is even if we don't have a direct method of dating the B site. Similarly, if we know that animal X lived after animal Y in the fossil record and X then shows up elsewhere with Z that gives us some rough data about Y and Z's relationship. I hope that explain the matter. JoshuaZ 16:43, 25 September 2006 (UTC)

Radiometric Dating is highly inacurate and and the geological column is just a construction of the diferent layers of rock and has not been found anywhere in the world. there is evidence that the world is young and the dates given by the geological column is far too old.

2002 champs talk 20:36, 2 July 2007 (UTC)

Uranium-Lead dating is accurate to 1 to 2 million years. Considering that we are dealing with hundreds of millions of years, I'd say that's fairly accurate. It may be inaccurate in that it couldn't pinpoint the exact year of the end of World War II, but for geologic purposes it's accurate enough.

What you are claiming is that if we measure the distance between Paris and London in kilometers, then it isn't reliable or accurate, and that we should use millimeters instead.

As for the geologic column, claiming you cannot find it anywhere in the world is denying what is right in front of your eyes. Go to any mountain range that has been uplifted, and you can see the layers of rock strata themselves. These could not have formed as a result of any kind of flood, since these layers can also be seen in mineshafts some 2 kilometers below the surface. To deposit that amount of silt and rock the Biblical flood (to which I am sure you are referring as evidence that the geologic column is false) would have had to exceed the total volume of water present on the Earth today, even counting the water trapped as ice at the poles and glaciers.

In any event, the claims you are bringing up, Champ, are relatively old and have been debunked since at least the 1940s. I'm sure a good read in modern geology journals would do you well.

It is my understanding that uranium-lead dating makes up roughly ONLY 4% of recognized radioisotope ages that are used to construct the theoretical geologic column because U-Pb dating rarely agrees with others. To claim U-Pb dating is "accurate to 1 million years" is baseless if you do thorough research. Accurate relative to what? Magma processes, Pb volatility in cold temperatures, leaching of U or Pb through some rocks, as examples can all throw off the decay model and ratio. U-Pb dating is only good if there is no dynamic process involved, but what are the odds of that? The geologic column is theoretical, it's guesswork, and based on hypotheses, no concrete evidence. Radiometric dating is inconsistent and theoretical and does not consistute evidence. The age of the planet is still unknown. The age of man, however, is becoming more and more conclusive. We will never know how old the planet was before our creation, however, and the age is irrelevant to human history. —Preceding unsigned comment added by 70.112.69.253 (talk) 05:00, 20 September 2007 (UTC)

interesting that creationists habitually leave unsigned posts, isn't it? there are several radiometric methods for dating rock formations, not just one, and the crux is that when two or three or more are used in the same sample, or in different samples in the same relative geologic position, they very closely agree. the idea that geologists "work blind" by simply sticking a rock into a radiometric measurement is laughable. Macevoy (talk) 02:00, 10 February 2009 (UTC)

Not to mention that (a) U-Pb dating may be out of agreement with other ages because it's the age through a closure temperature. One age says when it cooled through a higher temperature, such as Sm-Nd. Zircon is extremely stable to high temperatures and is stable in weathering. Dated zircon crystals are the ones that do not have lead loss, and even those with lead loss can provide useful information through the concordia. This thread is really old, and the creationist claims do not seem to have any basis here. I suggest archiving unless there are other things of note to say.

Some rock layers are accurately dateable, most are not. Using stratigraphic principles, those layers that are not dateable can be dated approximately around the correct age. This would be a good topic to cover. Hardyplants (talk) 02:26, 10 February 2009 (UTC)

That sounds like a good idea - I'm going to start a new section to discuss it, as this one is very cluttered, and copy/paste your comment there. Awickert (talk) 02:50, 10 February 2009 (UTC)

1. Paleomagnetism
2. Radiometric dating
3. Index fossils
- Parsa (talk) 05:31, 22 March 2009 (UTC)

Can we improve readability?

The article currently reads: "Evidence from radiometric dating indicates that the Earth is about 4,570 million years old (expressed with m.y.a. or "Ma" as in "it dates from 4570 Ma")."

While this is technically correct, most people do not speak this way. If something is thousands of millions of years old, they usually say it is billions of years old. Since I am new to the article, I wanted to raise the issue here first. How about saying it is 4.57 billions of years old (4.57 Ga)? RonCram 13:49, 15 December 2006 (UTC)

By the way, I have been informed by a friend that Ma stands for Mega-annum (thousands of years), Ga stands for Giga-annum (billions of years) and Ea stands for Exa-annum (quintillions of years). So the definition in the article should be corrected as well. RonCram 13:53, 15 December 2006 (UTC)

"Billion" is an ambiguous word meaning either 10⁹ or 10¹² depending on the linguistic history of the region, which is why we try to avoid it. Ga is unambiguous but still generally needs to be introduced. I agree though that the sentence is somewhat stilted. Dragons flight 13:57, 15 December 2006 (UTC)

No such thing as "basin groups", "Imbrian" or "Nectaran" eras for Earth.

The Earth's geologic time scale does not include a "basin groups", "Imbrian" or "Nectarian" era. This is pure fabrication. I propose that these references be removed. Also, the term "basin groups" is not applied to the Moon either. This is either an archaic informal term, or inaccurate information propogated by the popular press and web. I will soon be proposing for deletion the {{Hadean Footer}} template, as well as the topic Basin Groups (see lunar geologic timescale). Lunokhod 18:58, 14 January 2007 (UTC)

I agree. Hadean itself of course is a valid unit for Earth, endorsed by the International Commission on Stratigraphy, which is more or less the ultimate say-so for Wikipedia, I guess (even though they spell it "Hadian"). Cheers Geologyguy 19:19, 14 January 2007 (UTC)

I removed the offending material. However, I have little confidence that the rest of the table is correct! Lunokhod 20:20, 14 January 2007 (UTC)

I'm pretty sure (not positive!) that the rest of the table and the child pages are consistent with the ICS nomenclature, which is as close to international agreement on this as there has ever been. Cheers and thanks - Geologyguy 20:34, 14 January 2007 (UTC)

It was not there last time I saw the timeline.--JyriL ^talk 14:49, 16 January 2007 (UTC)

• To the contrary, the Basin Groups and Cryptic stages have a long standing, at least 17 years, basis. See Harland, Walter Brian , et al. (1989) A Geologic Time Scale 1989 Cambridge University Press, Cambridge, UK, Fig. 1.7 on page 10 and the appropriate entries in the GeoWhen database, footnoted to the table in the article. The ICS has not deigned to address subdivisions to the Hadean yet, but the lunar subdivisions have been applied in general to the Hadean. The article is clearly marked "Their use for Earth geology is unofficial." --Bejnar 02:34, 16 January 2007 (UTC)

The base of the "Imbrian" and "Necaran" eras for the Moon are based on the stratigraphic marker of ejecta from the Imbrium and Nectaris basins. How could one possibly use this stratigraphic marker to subdivide relative geologig time on Earth? Lunokhod 15:19, 16 January 2007 (UTC)

If the names refer to time, it is no problem, just as "Permian" can apply to time periods worldwide. If the names refer to rocks, that's another story. Geologyguy 15:23, 16 January 2007 (UTC)

Sure, I agree, but consider this: The age of the Nectaris basin is not well known. It was once thought to be 3.92 Ga, but now some are suggesting an age of 4.1 Ga. The important point is that this controversy does not affect the lunar geologic timescale, because it was constructed on stratigraphic principles! In my opinion, applying lunar terms to Earth implies that there was some commonality of processes occurring on both bodies during the time interval. This has certainly not been proven to be the case (though some have suggested that both planets experienced a "spike" in the cratering rate between the Nectarian and Imbriam era; this is controversial). Lunokhod 15:46, 16 January 2007 (UTC)

• I guess my only thought (now that I see, as Bejnar points out, that the Hadean lunar subdivisions are flagged as unofficial for earth - I missed that earlier) is that throughout the Earthly geologic time scale WP has been quite consistent in using the ICS nomenclature, even though some reputable sources such as those Bejnar cites (also, Paleos [2]) do use them for divisions of earthly time. But with the "unofficial" marking it is not really awful, I guess, just slightly inconsistent in not adhering to ICS like the rest of it does. No strong feelings either way, as long as usage is clear. Cheers Geologyguy 04:27, 16 January 2007 (UTC)
• Let's try to be consisted and follow the ICS nomenclature. If the lunar periods are not used as Hadean periods even unofficially among experts, then there is no point to mention Earth in the articles. The Hadean footer template is therefore redundant and can be removed.--JyriL ^talk 14:49, 16 January 2007 (UTC)
• I have added this sentence to the footnote in the table concerning the Hadean: The Hadean has also sometimes been called the Priscoan or the Azoic. Sometimes, the Hadean can be found to be subdivided into the Cryptic, Basin Groups, Nectarian, and Lower Imbrian eras (the latter two of which are based on the lunar geologic time scale), but this practice is not too common. Please feel free to change this if it is not clear. Lunokhod 11:21, 17 January 2007 (UTC)

Basin Groups article proposed for deletion.

The Basin Groups article (discussing a purported lunar or terrestrial geologic era) had been proposed for deletion. Please leave your comments on the appropriate page.Lunokhod 10:35, 15 January 2007 (UTC)

Epoch link in "Graphical timelines" is irrelevant

The link to "epoch" in the "Graphical timelines" section of the article seems to lack a purpose. It links to a disambiguation page, which, when referring to geological time, links to "Era", which is not the same thing as an epoch, epochs are a small part of eras. Should not this link be removed, as epochs are explained later in the article? Or perhaps link to lower in the page to the table of geologic time? There is no such page concerning only epochs in a specifically geological sense, so there should not be a link to a disambiguation page.Yelling Bird 02:30, 16 March 2007 (UTC)

recent Nature article

This article should probably incorporate the recent Nature article that argues (based on molecular and fossil data) that many mammalian lineages arose in the Cretaceous period and didn't diversify until about 10 - 15 million years after the dinosaur extinction. Matthias5 13:47, 29 March 2007 (UTC)

Proposed merger

I have suggested that Period (geology) be redirected here as there seems to be no distinct content there.--Keith Edkins ( Talk ) 19:48, 4 August 2007 (UTC)

Units, Ma vs Mya

According to Annum, the unit Mya is now depricated, with Ma as the appropriate unit. Is there disagreement with the updating the article to reflect this? - Davandron | Talk 15:10, 20 August 2007 (UTC)

Agreement on units, merger, Nature suggestions

IMO...Yes the Nature article should be incorporated. Yes Period (geology) definitely should be merged, it is very much a subset of this article. Yes, Ma is pretty much the default usage now and should be preferred; hopefully no disagreement arises with that. [Jim Eckert, Yale U.] —Preceding unsigned comment added by 130.132.22.88 (talk) 23:09, August 29, 2007 (UTC)

Color choices

Somebody please explain the selection of colors in "Table of geologic time". What's their origin? What do they represent? —Preceding unsigned comment added by 194.103.205.101 (talk) 10:19, 18 September 2007 (UTC)

They follow quite closely the colors assigned to time periods by the International Geologic Time Scale by the International Commission on Stratigraphy. Cheers Geologyguy 13:33, 18 September 2007 (UTC)

Actually, the colors in the article for the big chart seem to be taken from the USGS standard, not from the ICS.

USGS: Divisions of Geologic Time—Major Chronostratigraphic and Geochronologic Units - PDF file

ICS: CMYK and RGB color codes for Geologic Time Scale 2008 - JPG image, the chart is here - PDF file

-- Parsa (talk) 06:21, 22 March 2009 (UTC)

Time Scale

Should we include the Quaternary time period? I'm also thinking, perhaps we should include the faunal stages, as well, such as the Aquitanian, Burdigalian, Langhian, Serravallian, Tortonian, Messinian and Gelasian. Perhaps even including things such as the Neolithic? What's your opinion, wikipedians? RingtailedFox • Talk • Stalk 21:17, 29 September 2007 (UTC)

I second the change in the graphic of putting in the correct Quaternary Period, I know it's still fuzzy about how this will jive with the pliocene but i don't think just ignoring it is any better. It should begin at the 2.588 mya mark as agreed on by the ICS and INQUA.Miglewis (talk) 21:28, 15 October 2008 (UTC)

style concern

The silly corkscrew diagram and other lame analogies are overshadowing the real information. 75.8.92.94 (talk) 21:04, 7 December 2007 (UTC)

Images inconsistent with content.

The images "Diagram of geological time scale" and "Earth history mapped to 24 hours" are inconsistent with the text, and with the "Graphical timelines" and "Table of geologic time" images. They also do not conform to the ICS geologic time scale, the convention we are following in this article. These images are confusing to the viewer and should either be explained or removed. —Preceding unsigned comment added by Rico402 (talk • contribs) 13:27, 8 January 2008 (UTC)

Astronomic time

While this article is about geologic time, it might be useful to put in a line delineating an astronomic eon from a geologic eon. Apparently an astronomic eon is just a unit of time equal to 10⁹ years (one billion years US, one milliard years UK), whereas the geologic eon is the longest unit of geologic time (excluding the Precambrian supereon, which I believe is one of a kind), of arbitrary length.

If anybody else can confirm this, I think a note should be included to this effect. —Preceding unsigned comment added by 75.187.197.2 (talk) 02:57, 22 January 2008 (UTC)

Agreeal to Merger "motion"

I agree with a previous post that there should be a merger of Period (geology) and Geologic time scale.
--riking8 (talk) 18:17, 11 February 2008 (UTC)
(Sorry, I have not made a user page!)

• Removing {{Mergefrom}} tagging as:

1. improperly initiated... no common discussion section given by tagging editor with his/her reasoning
2. beyond reasonable time to junk up the article with no discussion
3. inappropriate in any event, both terms in official used in the official geological periodization system.

best regard // FrankB 17:09, 16 June 2008 (UTC)

TODO -- Fix Circular Definitions

Other Articles, particularly disambig pages are using redirected terms such as "Age", Epoch, and so forth which following the links from terminology Stage (geology) then links to, while Age (geology) just links back to this article. In short, the Terminology section BADLY needs to have a bulleted or table organized heirarchy and definitions for those who aren't familiar with the distinctions, as other writers/editors are assuming the distinctions and defines are being made herein.

“ Stage is a term defining a package of rocks formed in a certain interval in time; it is equivalent to the term age (geology) defining the interval of time itself, although the two words are often confused in informal literature. ”

1. Specific problem (One of several I found doing cross-discipline/cross-article edits) The (Stage (geology)) stages article says the above... making it clear [via the redirect to ages (expanded above)] that there is some distinction between stages and ages, but puts one right back via the redirect to the starting point. Education value=0, frustration and stupidity factors=Very High to chart topping.
   
2. Specific problem: Redirects are not tagged with categories, {{R to section}}, and #Section links See:
   1. this for proper redirects tagging,
   2. and line 17 of this, for a start or at least proper clues to other editors. Alternatively, could use {{redirectstohere}}, which in this case, if my suspicion that a number of redirects hit in that section title, and that is where you all want to handle this kind of needs issue, would be the best approach. Both editors changing a redirect (hopefully into a whole article) and those fiddling, are then on notice related changes must be made.
3. redirectstohere, has the added benefit to the users too, in that they aren't clueless when one link click plops them onto a page with title which doesn't even have the key word in the title.

It's not my mess, so have at it —it's sucked up too much of my time already — but do give some thought to the readers! // FrankB 18:40, 16 June 2008 (UTC)

While I'm here

The following five timelines show the geologic time scale to scale. The first shows the entire time from the formation of the Earth to the present, but this gives little space for the most recent eon. The second timeline shows an expanded view of the most recent eon. In a similar way, the most recent era is expanded in the third timeline, the most recent period is expanded in the fourth timeline, and the most recent epoch is expanded in the fifth timeline.

Horizontal scale is Millions of years (above timelines) / Thousands of years (below timeline)

This template Template:Timeline Geological Timescale(edit talk links history) is awfully fuzzy to read. Ironically, it's what brought me into this last hour wasted, as I was trying to clarify terms across articles. Font colors on background color choices and font selection really need worked out better. Especially the Hadean and next following.

Submit breaking it into four or five rows would give a better overall product, and the bottom links in some sections are mis-linked to null pages, specifically under Paleoproterozoic:

1. http://en.wikipedia.org/wiki/Orosirian -- correct
2. http://en.wikipedia.org/w/Orosirian -- null page error, amongst several. (Try testing it and see) // FrankB 18:54, 16 June 2008 (UTC)

Circular scale, ugh...

As a professor of evolutionary biology for more than a decade, I cringe seeing the circular time scale at the very top of this page. At this first glance, persons new to the concept will follow the circular arrow to conclude that we will soon be re-entering the Hadean "after midnight" (or noon), and that the Earth and Moon will soon be formed again. Circular time scales have only 1 use (of questionable value), which is to use a familiar cyclical clock-like metaphor to illustrate how old the Earth is relative to portions of its history, such as the human presence. "If the history of the Earth was 12 hours, mammals appeared at 11:00 and human beings first appeared at 11:59:57", blah blah blah. But the metaphor is not good enough to continue justifying the use of a circular time scale, which is misleading. It is also not better than a simple linear time scale, which suffices just as well to show a proportional comparison between portions of history and the total history. If anyone here insists on keeping it circular, then at least spiral it out a bit so that humans don't look like they are imminently re-entering the Hadean, or else about to slam into that black line. 198.187.251.52 (talk) 20:50, 25 January 2013 (UTC)

I mean: the graphic is bad on so many levels. Having the names of "Hominids, Mammals, Land Plants, Animals" etc etc to the right of the ineffective black dividing-line, gives the impression that these organisms existed at the time of the formation of the Earth, in the Hadean. Please put a conventional time scale at the top of this page! It took geologists centuries to develop, which is why it is still the best way to depict geologic time. 198.187.251.52 (talk) 20:55, 25 January 2013 (UTC)

And I agree with the poster below who said, "I'm sorry but as a research geologist I think this is just ridiculous. The first thing I think is "Wow! the world is going to end and we will go back to the beginning of earth!" There are much better ways to show that time is expansive."..... 198.187.251.52 (talk) 21:18, 25 January 2013 (UTC)

Hello? Unless there's some participation in this "consensus" process, I'm going to assume that nobody else cares about this, and I'll implement removal of the pie-scale and replacement with a traditional time-scale within 1 week. If nobody else speaks up, it won't be vandalism when I make that change. Speak now, or.... 198.187.251.52 (talk) 16:43, 28 January 2013 (UTC)

So nothing happened for another 8 years? Also, why does "First vertabrate land animals" point to the yellow stripe labeled "Land plants"? --Felix Tritschler (talk) 16:35, 3 October 2021 (UTC)

Interpolation

This commment is copied/pasted from above, and I started a new section to discuss it: Some rock layers are accurately dateable, most are not. Using stratigraphic principles, those layers that are not dateable can be dated approximately around the correct age. This would be a good topic to cover. Hardyplants (talk) 02:26, 10 February 2009 (UTC)

I agree that this would be useful. Does anyone have a suggestion as to where this would be useful to insert? Off the top of my head, the methods used for dating units that are not directly absolutely datable are:

• Interpolation of sedimentation rates
• Correlation with units which contain material that may be absolutely dated
• Correlation of fossils present with absolutely-dated sections with the same fossils
• Cross-cutting and erosional relationships to provide upper upper or lower bounds on when the units could be deposited.

Awickert (talk) 02:56, 10 February 2009 (UTC)

Another significant contribution is the use of the climatological effects of Milankovitch cycles to date sequences either absolutely (eg in terms of years before present) or relatively (in terms of intervals). This is because the effect of long-duration cycles in the Earth's orbit - precession, obliquity and eccentricity - can be used to interpret sedimentological cycles in a manner analogous to the use of tree-rings to date wood, except that the Milankovitch cycles span many thousands of years rather than sequences of single years. This approach has made important contributions to the chronology of the Cenozoic and many other parts of the Phanerozoic (cf eg A Geologic Time Scale 2004, Gradstein et al). The use of annual and sub-annual (eg tidal) laminations in lake and some marine sequences has also made very important chronological contributions. Orbitalforam (talk) 18:48, 15 May 2011 (UTC)

Earth clock

Mapping geological time units to 24 hours is a potentially useful educational tool, however the present graphic is erroneous. Rescaling the dates presented in the article to 24 hours would have the Archean ending at 10:52 (not approx. 18:40 as indicated) and the Proterozoic much longer. The 2 ma of the Quaternary represents 37.8 seconds (not 17). Some of the other boundaries look a little off too.

I don’t have the graphics skills or software to replace the clock image so for now shall simply remove it. If anyone cares to redo the graphic I’d be quite happy to contribute a full set of calculations. Shythylacine (talk) 07:06, 7 March 2009 (UTC)

Maybe a simple way to do it would be to use the ICS chart divided by 4.567 billion years, and make a pie chart in Excel, which we could then annotate. Anybody think this is too shoddy? Awickert (talk) 07:16, 7 March 2009 (UTC)

Another suggestion I have come across recently (documentary & book) is a 365 day calendar representing the timespan of the earth. Now I am not suggesting to replace that with the 24 hour day but a nice addition if someone wants to take up the gauntlet :-) -- Phoenix (talk) 08:38, 7 March 2009 (UTC)

That sounds like a cool idea - do you know how to make a succinct graphic out of it? (The nice thing about the clock was the circle.) Awickert (talk) 08:45, 7 March 2009 (UTC)

OK, here's an Excel pie chart clock, pretty shoddy compared to the original image, but accurate. Now, where to put it? I think the original was out of place in the history section so would suggest below the graphical time-line. It wouldn't need much text, eg:

"Another method of envisioning the geological time scale is to compress its vast length to 24 hours.

Once again, at 37.8 seconds the Quaternary is too short to display on a clock face."

So, is it too shoddy? Perhaps superfluous? Shythylacine (talk) 06:54, 8 March 2009 (UTC)

I'm glad I checked Wikipedia - I was just starting to make one of my own, so I'll stop. I actually really like it - I say it should definitely go in, and is a really good graphic! Awickert (talk) 08:45, 8 March 2009 (UTC)

Thanks for the image but could you add the Hadean? I found this image and since it is made by the US government I believe we can upload it or just use it as a reference (here's another one). Maybe a clock in a clock might be a good idea? Strike all that wikipedia already has a nice one... I'll change it right now.

As for the calendar idea it was shown as a full year calendar with all the days coloured to represent the geological times. So you see all 365 days at once and the amount of time each eon/period/etc took up. -- Phoenix (talk) 09:46, 8 March 2009 (UTC)

Cool! But now I like both; the bottom one looks nicer, and the top one has all of the geological periods in 2 circles. I wonder if it would look bad to use both, or if we can get away with it. Awickert (talk) 10:25, 8 March 2009 (UTC)

Problem is you can't read the text on the lower image - even at the 600 pixel scale it's a challenge for my bleary eyes (maybe I need more coffee to clear the morning fog). Point being, do we need the second, unreadable image just 'cause it's "prettier" - seems redundant to me. Vsmith (talk) 13:03, 8 March 2009 (UTC)

Personally it showed up just fine on my PC at 600px. Well since the newly created one was re-inserted I placed the File:Geologic clock.jpg image I found on wikipedia higher since the articles title is Geologic time scale. But can anyone edit the File:Earth Clock 2.gif image to include Hadean? If not it should just show the pre-cambrian. -- Phoenix (talk) 03:04, 9 March 2009 (UTC)

I omitted the Hadean on account of its informal status, but have since seen that ICS use it (informally) on their 2008 [[3]]. So yep, agree that Hadean needs to be in. The term is such evocative counterpoint to all those -zoics too ;) Shythylacine (talk) 10:39, 9 March 2009 (UTC)

This article does not need two clocks. Of the alternatives I prefer the one with the black background for its greater information density, so shall delete mine. I also prefer its aesthetics - the round clock of earth in the black of space-time. It's not perfect, but it's not boring either. The present layout with the clock next to the introduction leaves space to add some caveats and disclaimers in an expanded caption. Will have a go at that now. Shythylacine (talk) 10:52, 9 March 2009 (UTC)

OK - but please leave it on Commons: I like it, and have some friends who teach intro geology who would find something like that useful. Awickert (talk) 00:05, 10 March 2009 (UTC)

I'm sorry but as a research geologist I think this is just ridiculous. The first thing I think is "Wow! the world is going to end and we will go back to the beginning of earth!" There are much better ways to show that time is expansive. Also, to my most important point, the geologic time scale's page should not focus on the relative time, but the names of the periods and their subsequent periods. That is why we go to this page. Why not just have a column going down from Haydean and zomming into the paleozoic, then mesozoic, then cenozoic. Please. This is just retarded how it is. You could even switch it out with that spiral from below. That gets the point across well.

(talk) 11:23, 25 July 2012 — Preceding unsigned comment added by 129.116.198.144 (talk)

Well if you do keep the image can you either edit or upload a version that has the Hadean in it? Either that or make it pre-cambrian :-) -- Phoenix (talk) 08:49, 10 March 2009 (UTC)

March 23, 2009 Vandalism

64.187.47.18 made a series of changes on March 23, 2009. Most were silly vandalism such as adding the everett to several random locations.

Two were more substantial. This person apparently removed the much of the "History of the Time Scale" section. This revision could not be easily undone, and restoring the section is beyond my wiki-abilities. This person also made a revision deleting several lines from the "Graphical Time Scale" section. Also could not be "undone". Could someone else fix these? —Preceding unsigned comment added by Ukemike (talk • contribs) 21:22, 25 March 2009 (UTC)

Time scale changes

I suggest that the eras in the Hadean Eon be removed. They do not reflect either the International Commission on Stratigraphy International Stratigraphic Chart 2008, the Commission for the Geological Map of the World Geologic Time Scale 2008 color coding, or USGS time scales (see below).

Also, the text states the colors are from the ICS standard, but this is not the case. They more closely resemble USGS time scale and geologic map colors.

-Parsa (talk) 02:31, 29 March 2009 (UTC)

I personally like having the Hadean subdivisions because, although not official, they are used in the literature.

The color issue has been brought up before; if there's a consensus to change the timescale templates to use the ICS colors, I'd say it would be a decent thing to do, and would help. Awickert (talk) 04:22, 29 March 2009 (UTC)

Page size

As of this posting, the page is 3.4MB in total! 59.167.39.47 (talk) 12:01, 28 April 2009 (UTC)

Help requested

In watching recent changes I came across this edit: [4]. Seeing this was a revert of a ClueBot reversion and noting a less than gentle appraisal of the redirect as it was, I reverted. The editor has taken issue with my reversion. With my limited experience in the technical details of the subject I am hesitant to take issue with the editor (even though I think the ClueBot version was correct). If the editors here could look into the matter I would appreciate it. If I'm making mountains out of mole hills, I will offer my apology in advance. Thanks. Tiderolls 15:33, 29 April 2009 (UTC)

including the terminology "age"

I was wondering in the Geologic time scale#Terminology the table of "Units in geochronology and stratigraphy" should include the classification systems of Age and The Great Year as footnotes.

In the Origin of Religion (part 2) it mentions that in the Ancient Science (Astronomy and Astrology), each 25,765 years is called The Great Year according to the 12 Celestial sphere Constellation, that is viewable from Earth. There hasn't been any new map/grid (proposals, theories, concepts...etc) published to the any research organization or to the general public and I think this infromation if perfectly valid, since current science still related information like Equinox, Solstices, Star navigation...etc. There is also scientific evidence that this time measuring system is based on the Earth's axial precession and each 2150 years is called an Age. --75.154.186.241 (talk) 22:59, 26 September 2009 (UTC)

Galactic Year

I've never seen the 'galactic year' used for purposes of geology other than on the linked page (which calls it a suggestion, not an accepted convention) and derivative Wikipedia entry. Moreover, the abbreviation "GY" is highly unfortunate as it may easily be interpreted as "gigayear" (properly "Ga"). I propose the section be deleted as non-notable. Orcoteuthis (talk) 21:30, 19 November 2009 (UTC)

Unreliable source - Muslimheritage.com material

Content from Muslimheritage.com / FSTC is an unreliable source, as discussed on Wikipedia:Reliable_sources/Noticeboard/Archive_18#History_of_Science. None of its publications are peer-reviewed, and its authors often exhibit a strong bias and incomplete or flawed citation practices. The site has been used as a source in numerous science and history of science articles to make extraordinary claims about Islamic invention and discovery. I am working to remove these extraordinary claims where they stem directly and solely from a Muslimheritage.com reference. Many of these claims were added by a user who has a history of using flawed sources for extraordinary claims, as discussed on Wikipedia:Requests_for_comment/Jagged_85. That page details numerous examples where claims from these sources contradict more reliable sources, on a scale which casts the entirety of the material originating from the site into doubt. If you would like to discuss this or any related removal with me, please leave a note on my talk page. Dialectric (talk) 12:05, 26 April 2010 (UTC)

Early Cambrian

There is a mess-up on the chart in the Early Cambrian section. The early is located in the Supereon when it shouldn't be there. I am not even going to attempt fixing it beacause I am not good at the table making stuff. Can someone fix this? Andrew Colvin | Talk 05:53, 4 June 2010 (UTC)

Misuse of sources

Jagged 85 (talk · contribs) is one of the main contributors to Wikipedia (over 67,000 edits; he's ranked 198 in the number of edits), and practically all of his edits have to do with Islamic science, technology and philosophy. This editor has persistently misused sources here over several years. This editor's contributions are always well provided with citations, but examination of these sources often reveals either a blatant misrepresentation of those sources or a selective interpretation, going beyond any reasonable interpretation of the authors' intent. Please see: Wikipedia:Requests for comment/Jagged 85. The damage is so extensive that it is undermining Wikipedia's credibility as a source. I searched the page history, and found 7 edits by Jagged 85 (for example, see this series of edits). Tobby72 (talk) 16:55, 18 June 2010 (UTC)

Children's books being used as a reference

I deleted references to the following book from this and several other articles today, on the basis that it is a children's book (aimed at 11–14 year old children, according to the publisher):

• Scheppler, Bill (2006). Al-Biruni: Master Astronomer and Muslim Scholar of the Eleventh Century. Great Muslim Philosophers and Scientists of the Middle Ages. New York: The Rosen Publishing Group. ISBN 978-1-4042-0512-3.

I do not believe that such a book can, by its very nature, be considered a reliable source; certainly such books don't seem to be considered appropriate by WP:SOURCES for example. (Note that I didn't delete the claim it was being used to support: I just replaced the reference with {{Cn}}.)
This change was reverted with the comment that "no evidence of unreliability yet adduced". As I say, I don't think that reliability or otherwise is the issue here: the book is simply unsuitable for a reference in an encyclopaedia. But as it happens, on the very page (86) being used as a reference (see Google books), we can find the claim that "Ibn Sina embraced the heliocentric theory" which is plainly false. The explanation on page 84 of that book about Biruni's reasons for placing the orbits of Mercury and Venus below that of the Sun also looks very confused to me.
If books such as this should be used as references for material such as this, could someone explain to me why, as I really don't see that it is appropriate.
Many thanks. –Syncategoremata (talk) 21:38, 18 June 2010 (UTC)

Individual Pages for Eras During the Archean Eon are Misrepresented a Eons

First off, I just wanted to note that this (the Geologic Time Scale) is truly a great addition to the ever-growing Wikipedia body of knowledge and I greatly appreciate the efforts of those involved to putting together the section.

I noticed the other day, while perusing the individual pages dedicated to the eras of the Archean Eon, that each of those eras, on their respective pages (in the colored graphics on the right side of the page), are misrepresented as eons. As I am relatively new to Wikipedia, I haven’t the ability to correct this and would offer the correction up to whomever is currently overseeing the aforemntioned pages. --Astro1001 (talk) 16:18, 5 August 2010 (UTC)

Thanks, the wrong template had been applied. I've removed Template:Geological eon as those aren't eons. Vsmith (talk) 21:43, 5 August 2010 (UTC)

Kaapvaal craton, Kalahari craton & Vaalbara

I would like to propose that these terms be inserted (with their respective links) together with the (Canadian Shield and the Pilbara Craton) under the Paleoarchean section as major events.
Furthermore would anybody be so kind and inform me as to what is required to improve the Kalahari craton page (http://en.wikipedia.org/wiki/Kalahari_craton) and the Kaapvaal craton page (http://en.wikipedia.org/wiki/Kaapvaal_craton) so as to meet Wikipedia's quality standards. Any help will be greatly appreciated.
Many thank SamiAEH (talk) 18:00, 16 August 2010 (UTC)

There is an incongruence in origin of animal phyla in the detailed scale. If there were trilobitomorphs since pre-cambrian (ediacaran according this scale), most of animal phyla were already established in that supereon, not in Cambrian. Trilobitomorphs are well-defined chelicerate, then we have to accept older origin of phyla. There were molluscan shells, already as gastropods or cephalopods, from pre-cambrian too. I would suggest anyone could take out "most modern animal phyla appear" from cambrian. One should search more about origin of phyla to write a better informatin about this... —Preceding unsigned comment added by 187.64.36.244 (talk) 15:48, 22 August 2010 (UTC)

Terminology: Late/Upper

I've tidied up the terminology section to make it a bit clearer that Upper/Lower refers to rocks and Late/Early refers to time. Hopefully I've got the intermediate right as well (middle = time, mid = rock), but that was based partly on memory and partly on the chart further down the page. Can someone less rusty confirm (or correct) this please. 62.172.108.23 (talk) 11:40, 1 September 2010 (UTC)

A comparative geological timescale

The graphic captioned "A comparative geological timescale" [File:Geological_Time_Scale.png] has some problems. The Miocene and the Holocene both are omitted from the Neogene in the fourth bar from the left (second to last bar), which is the most serious problem. Whether the fifth bar (subdivisions of the Holocene) even belongs in a graphic for this article is another question. --arkuat (talk) 06:18, 3 September 2010 (UTC)

Spiral graphic

The spiral graphic (http://en.wikipedia.org/wiki/File:Geological_time_spiral.png) is possibly outdated. According to the International Commission on Stratigraphy the Pennsylvanian and Mississippian are not periods, but epochs of the Carboniferous. It's a great graphic, though. (I also contacted the author of the original poster, via http://pubs.usgs.gov/gip/2008/58/) --Furrfu (talk) 19:15, 8 September 2011 (UTC)

Letter designations for periods etc

I wonder if we don't put somewhere within this page some reference to the letters which stand for each of the Phanerozoic periods and indeed the eras and eons of the Precambrian. I'm talking of course about N=Neogene, G=Palaeogene, K=Cretaceous, J=Jurassic, T=Triassic, P=Permian, C=Carboniferous, D=Devonian, S=Silurian, O=Ordovician, E=cambrian and X=Neoproterozoic, Y = Mesoproterozoic, Z=Palaeoproterozoic and A=Archaean. Many are straightforward enough, others may not appear so at first glance - some explanation for the lay-reader might assist. I don't know but I have always presumed that these were agreed by the ICS. Perhaps someone who is more familiar with the subject than I, might care to comment? cheers Geopersona (talk) 09:49, 12 December 2010 (UTC)

This article is in dire need of a controversy section

Kent Hovind & his ministry is an infamously unreliable source -- dismissed even by many creationists, and thus no basis for adding material to the article, and a very poor basis even for article talk discussion. WP:NOTAFORUM
The following discussion has been closed. Please do not modify it.
The stance of Creation Science Evangelism as well as CMI and many other creationist ministries is that the earth is NOT billion of years old as is seen throughout their audio-video materials available online such as this one from CSE http://www.drdino.com/seminar-part-1-the-age-of-the-earth In regards to the carbon dating bezerk stuff which is all one big huge assumption based on the CIRCULAR REASONING of the geologic tables (the fossils are dated by the layers and the layers are dated by the fossils) their stance is also the same, as in it being an utter fairy tale. Here is one source content from CSE http://www.drdino.com/questions-and-answers-seminar-part-7a Someone REALLY has to add this section to the article due to the fact that after watching these 2 videos in their entirety (the first deals with the ASSUMPTION that the earth is millions of years old based on the same ALLEGED datings by carbon dating which is covered in video number 2) one CAN NOT ascertain that the statement according to which the earth is billions of years old (As the fairy tale line says "Once upon a time") is anything buth a lie, myth and deliberate speculation. PLEASE ONLY COMMENT TO THIS POST AFTER WATCHING BOTH VIDEOS YOU CAN NOT APPROPRIATELY COMMENT IF THE CONTENT THAT IS ACCUSING THIS HAS NOT BEEN VIEWED AND UNDERSTOOD Sergiu-Daniel (talk) 18:08, 16 December 2010 (UTC)

Please don't shout. And as noted in reply to your identical rant on talk:Age of the Earth, take it to Dating creation or the religion article of your choice. This article is about the geologic timescale and its development. Vsmith (talk) 18:29, 16 December 2010 (UTC)

OK, scrap Hovend, what about CMI http://creation.com/age-of-the-earth and other creationist ministries that clearly refute the "once upon a time the earth formed" phrase and support the young earth theory. Their arguments are the same as Hovend's, the gology column is based on circular reasoning, the layers are dated by the fossiles and the fossiles are dated by the layers. Can any of you give me one bit of scientific evidence for this fairy tale of a geology column? Who came up with the numbers? The radiocarbon dating that can't properly date a NY Times paper, or anything else of known age for that matter? Here are some of CMI's arguments: Many fossil bones “dated” at many millions of years old are hardly mineralized, if at all. (http://creation.com/dinosaur-bonesjust-how-old-are-they-really) They have at least 101 arguments against your holy geology column which atheists venerate so religiously!!! "Billions of years agooooo........" Do you think that 101 arguments from only 1 website (with accredited scientific research) is enough for you guys to start a controversy cathegory on this article??????????????????????? — Preceding unsigned comment added by Sergiu-Daniel (talk • contribs) 20:49, 30 December 2010 (UTC)

How many arguments do you need me to post here before someone will start a controversy section on this article? There obviously is one between evolutionists and creationists on this very subject, why has Wikipedia fallen behind at catching up with this? Sergiu-Daniel (talk) 20:58, 30 December 2010 (UTC)

No, there is no controversy about the geological time scale. A few religious fanatics will try to claim otherwise, but this is an article about science, not about fringe religious sects. DuncanHill (talk) 21:11, 30 December 2010 (UTC)

OK. When I'll have some spare time after the holidays I'll bombard this discussion page with REAL SCIENTIFIC facts against this overrated religious geology column that is always being introduced with the oh so venerated "unce upon a time" (billions of years ago...) Sergiu-Daniel (talk) 22:28, 30 December 2010 (UTC)

<chuckles> First you'd have to find some "real scientific facts". Given that you have cited nothing but Creationist Christian apologetics here & on Talk:Age of the Earth, I consider (i) that it is unlikely that you even know where to look for them & (ii) that your claim that the "geology column" is ludicrously WP:POT. In any case controversy sections are depreciated per WP:STRUCTURE. Hrafn^Talk_Stalk^(P) 03:09, 31 December 2010 (UTC)

So here is one argument that is against the geologic time scale. http://www.icr.org/article/445%20/ The Polystrate Trees and Coal Seams of Joggins Fossil Cliffs initially discovered by Sir Charles Lyell, friend and colleague of Charles Darwin. Why aren't his findings not even mentioned on this article? Petrified trees sitting upside-down throughout the hole column. This really shoots the geologic time scale between the eyes...Sergiu-Daniel (talk) 21:55, 6 January 2011 (UTC)

I believe I said "real scientific facts" -- not bogus pseudoscientific claims, made by a geological engineer not a geologist, and published by an organisation that could not even convince the state of Texas (hardly a liberal hotbed) that what they were teaching is "science education". For a scientific treatment of the topic, read Polystrate fossil, and then the sources cited there. Hrafn^Talk_Stalk^(P) 04:29, 7 January 2011 (UTC)

See also Creationist Claim CC331, which links to further rebuttals. I would note that this claim is old and long-debunked. Hrafn^Talk_Stalk^(P) 05:10, 7 January 2011 (UTC)

Please stop feeding the troll and holding up this soapbox. This is not the place for debunking science, there are plenty of blogs in cyberspace. It's time to close down this discussion as an abuse of a wikipedia article talk page. --Kleopatra (talk) 05:15, 7 January 2011 (UTC)

Errors in Terminology section

"If the entire history of the Earth was to be compressed into one day, ... the first life will appear at 6:00 pm"

That's about 1.5 billion years ago, yet the graphic shows that life originated on earth at least 3.8 billion years ago. I guess "life" in that section should be corrected to "multicellular life" since that appears to be what the graphic indicates. Ashwan (talk) 18:36, 8 November 2011 (UTC)

Also:

"the Moon will be forming at 5:00AM"

That would put the moon formation sometime around the end of the Archaen. The time should be more like 12:05AM. 65.102.180.83 (talk) 05:10, 5 December 2011 (UTC)

supereon: when? where? who?

The timescale chart in this article includes a unit of geological time called a "supereon". Since I have never encountered this term before, I would be interested to know more about it. For many years the term "precambrian" has been used to (informally) identify any time earlier than the cambrian (period); I guess the motivation for this was that, throughout much of the early development of geology, fossil evidence (more or less) started in the cambrian. To formalise this by creating a time unit corresponding to the precambrian is not unreasonable (since the term "precambrian" is not assigned to any other geological time unit). However, naming the following supereon the "cambrian" is unsystematic (since it duplicate the long-establised name of the cambrian period). It seems very unlikely to me that an organisation such as the International Commission on Stratigraphy would adopt such an unsystematic practice. Can anyone identify a primary source for the formal adoption, firstly, of a time unit called "supereon", and, secondly, of a supereon called the "cambrian". When was it first published? In what article or publication? By whom? FredV (talk) 19:42, 13 November 2011 (UTC)

The International Commission on Stratigraphy's guidelines explicitly permit the use of 'super-' and 'sub-' when applied to stages/ages, series/epochs and periods/systems so as to enable useful grouping and dividing though no reference appears to be made to either eras/erathems or eons/eonothem in this respect - either in support or to the contrary. See http://www.stratigraphy.org/upload/bak/chron.htm It may perhaps then be seen as a natural and convenient extension (if not officially sanctioned) of the application of the prefix 'super-' to collectively describe the Precambrian eons which alone (maybe?) in stratigraphic terms would otherwise have no following noun - so 'supereon' does perform a role. However any reference to a 'Cambrian Supereon' would simply be an error. cheers Geopersona (talk) 05:40, 22 February 2012 (UTC)

Correction needed in Table 2

In the table that lists the "Units in geochronology and stratigraphy", the number of eras is listed as 12. But from the time scale it is pretty much clear that the number is 10. I believe that when removing the eras from the Hadean eon this number went unnoticed. — Preceding unsigned comment added by 122.178.18.231 (talk) 16:51, 14 November 2011 (UTC)

Thanks, I changed it to 10 - I don't believe that there are any formally accepted subdivisions of the Hadean. Mikenorton (talk) 17:51, 14 November 2011 (UTC)

time scale condensed into a single day

Whilst I am aware this analogy gets used, I am doubtful as to its value in an encylopaedia article. It does not really add value to the extensive scientific presentation of the time scale presented above. Would we also end up comparing the Structure of the Earth to a peach? Babakathy (talk) 07:31, 6 January 2012 (UTC)

I would have to agree. Hrafn^Talk_Stalk^(P) 08:06, 6 January 2012 (UTC)

So I will also have to reluctantly agree. (Rats.) I have to remember WP:NOTTEXTBOOK: "Wikipedia is an encyclopedic reference, not a textbook. The purpose of Wikipedia is to present facts, not to teach subject matter." I'm a teacher, and just naturally fall into what I do best.

On the light side, Babakathy, no, not a peach; an apple! :-) Yopienso (talk) 10:13, 6 January 2012 (UTC)

Ah yes, shows more heterogeneity than a peach...Babakathy (talk) 10:48, 6 January 2012 (UTC)

Agree with all. Not encyclopedic, its as simple as that. Cadiomals (talk) 19:04, 6 January 2012 (UTC)

Historical use of terms era and period

We ought perhaps to make reference in the article to the fact that the fourfold division of Earth history employed by early geologists made use of the term era for each of these divisions. Two (the primary and Secondary) were abandoned at an early stage but use of both Tertiary Era and Quaternary Era continued into modern times - these eras being subdivided into the Miocene Period, Eocene Period etc. Only later was the Tertiary reclassified as a period itself and its subdivisions downgraded to epochs -I am not sure exactly when that occurred but for example Britain's Institute of Geological Sciences' fourth edition of the regional guide to the geology of 'The Wealden District' of southeast England (which was published in 1965) refers to the Tertiary, the third geological era (p45) and goes on to talk about the Eocene System and so on. cheers Geopersona (talk) 05:53, 22 February 2012 (UTC)

Completely Earth-centric

Mercury also has eras. It would be nice to list other planets/bodies that have a time scale. Solar Apex (talk) 08:25, 23 April 2012 (UTC)

It also would be nice to create a comparative time scale for planets. Solar Apex (talk) 08:27, 23 April 2012 (UTC)

I have absolutely no idea what this is talking about! The Geologic Time Scale to which the main article refers is a human construct, developed to organise the observed structure of the geological record. Since Geology is study of the structure of the Earth, it is no surprise that the timescale only refers to the Earth. What does it mean to say "Mercury (or the Moon, or Rigel) have eras or have a time scale"? If it just means they have existed for a long time, then most of the objects in the universe have eras. If it means that a study of their structure would reveal recognisable stages of change with time, this is very likely true, but until such a study is undertaken, there will be no defined time scale; I am not aware of any observation-based time scale for any astronomical body other than the Earth (we simply don't have the millions of stratigraphic observations required to establish such a time scale). FredV (talk) 12:43, 23 April 2012 (UTC)

We know comparatively little about the geological histories of other planets and moons within our solar system but it seems that we do know enough to have established geological time scales for some of them eg Mercury, Mars and our own Moon. These might be considered provisional divisions of the timescales just as we have been able to refine the timescale for the evolution of the Earth. Now, the lunar and Martian subdivisions are styled 'periods' whereas the timespans which they occupy equate broadly with terrestrial eons. I can see that there may indeed be merit in laying out, side by side, these timescales and those of other nearby bodies with a view to making comparisons - after all there are elements of shared history amongst the members of our solar system family - the early and late heavy bombardments come to mind. This article is not the place to do so however. cheers Geopersona (talk) 19:16, 23 April 2012 (UTC)

Just to clarify my point. The term "geologic time scale" applies not only to the Earth even though "Geos" in Greek means Earth (See Lunar geologic timescale as an example). So I would expect this to be an article that talks about what geologic time scale is in general with references to geologic time scales for some bodies, the Earth included. For example, most of the contents of this article could be transferred to something like "Geologic time scale of the Earth". Or even better, just rename this article to "Geologic time scale of the Earth", and have another article about general stuff. Certainly, there is a value of laying timescales side-by-side, but on a separate page. This is merely a suggestion, not something I'm insisting on. Solar Apex (talk) 21:49, 23 April 2012 (UTC)

Sorry Solarapex but I can't follow your argument. The geologic(al) timescale is something that has been devised so as to aid our understanding of, and enable structured conversations around, the history of the particular planetary body on which we live ie Earth. It was not devised so as to be able to describe the histories of other bodies - indeed it would be largely irrelevant given that the evolution of those bodies would be governed for the larger part by processes inherent to those worlds. Geopersona (talk) 21:05, 6 November 2012 (UTC)

While I wouldn't agree with trying to bring in the histories of other planets to this article, I do see that the original commentators (Solarplex, Fredvanner) do have a point. I've added a paragraph with links out to the separate pages for Geology of Venus, Mars, Moon, etc. The Late Heavy Bombardment also gets a mention, but since there continues to be debate over it's significance - or even existence, it isn't mentioned heavily. (Recent work, whose references I forget, questions if any significant amount of material was added to the Earth's structure in this period. Extra-solar planets are mentioned as a "why not." Aidan Karley (talk) 22:56, 9 May 2016 (UTC)

Period (Geology)

My class is reasearching rocks and we can't figure out why there is no 'Period' timescale. Help please?Airlinesguy (talk) 23:20, 27 May 2012 (UTC)

ICS Updated time Scale

The ICS has released a revised version of the official geologic time scale used in the templates and articles associated with this page. See the new version here: [5] Since we use this as the source for all dates, they need to be adjusted to reflect the changes. MMartyniuk (talk) 19:21, 21 August 2012 (UTC)

Agreed, this should probably be raised at the template talk page. Mikenorton (talk) 17:11, 22 September 2012 (UTC)

There were also updates in 2015 and 2016. I've put a comment to this effect into the main page, but since this is going to be a constantly moving target, there really should be a technique for dealing with such moving targets. I guess that sports fans (I'm not one ; I loathe sports with abiding hatred) have some techniques since they have never-ending data streams too, but I don't know how they deal with it. Aidan Karley (talk) 14:59, 9 May 2016 (UTC)

What the hack is "Ga"?

The clock representation diagram and the caption uses the term "Ga", which is never defined in the text. — Preceding unsigned comment added by Drozdyuk (talk • contribs) 14:25, 5 November 2012 (UTC)

Thanks for pointing that out, I've linked it and explained it. Mikenorton (talk) 15:13, 5 November 2012 (UTC)

Ga = Gigaannum = One billion years or one thousand million years - Used mostly by astronomers and geologists. Cadiomals (talk) 16:31, 5 November 2012 (UTC)

Thanks! Sorry I didn't see your reply, I wish there was some way to tell wikipedia to notify me when someone replies to my comment. Drozdyuk (talk) 20:38, 3 December 2012 (UTC)

Horizon?

The term "horizon" is used without a definitino in the text. I think I know what it means, but it is only very loosely related to any term on the Horizon (disambiguation) page. Can an expert please create a Horizon (geologic stratum) page? -Arch dude (talk) 22:38, 31 December 2012 (UTC)

I've had a go at that - see Horizon (geology) - still needs a bit of work though. Mikenorton (talk) 00:00, 29 January 2013 (UTC)

Thanks! That's a good start and does give an intrested layman access to the right information even if it were never improved. I suspect it will serve as a good nucleus for incremental improvement. -Arch dude (talk) 01:01, 29 January 2013 (UTC)

Expanded description for Condensed graphical timelines

An editor removed some explanatory text from this section in good faith, on the grounds that the successive changes in scale are self-exlpanatory. I added this text originally because I did not find it to be self-explanatory. If we reach consensus that most readers do not need this text, we should in fact remove it, but I feel that I am unlikely to be the only reader who did not find it to be obvious. -Arch dude (talk) 23:30, 31 March 2013 (UTC)

I had moved all the text into the template. Here is the template shown below my comment. Do you see the description? Yes. Also I moved all the text in 1 paragraph. That means that you just made 2 copies of the paragraph. So you should undo the edit you made. 24.218.110.195 (talk) 11:55 10 April 2013 (UTC) 7:55am 04/10/2013 EDT. The following five timelines show the geologic time scale to scale. The first shows the entire time from the formation of the Earth to the present, but this gives little space for the most recent eon. The second timeline shows an expanded view of the most recent eon. In a similar way, the most recent era is expanded in the third timeline, the most recent period is expanded in the fourth timeline, and the most recent epoch is expanded in the fifth timeline.

Horizontal scale is Millions of years (above timelines) / Thousands of years (below timeline)

OK. I'm not sure what happened, but when I re-instated the text, the the text that is now in the template was not showing in the article. The template text looks good. Thank. I removed the now-redundant article text. -Arch dude (talk) 21:05, 11 April 2013 (UTC)

Hello Arch dude I have moved the remainder of the text that wasn't in the template into the template. Plus I just wanted to let you know that nearly almost all computers or screens show the text, maybe 99.76% shows it my guess. 24.218.110.195 (talk) 02:58 14 April 2013 (UTC) 10:58pm 04/13/2013 EDT.

What is happening in this section is beyond my Wiki-understanding, but there seems to be a bug in the template(s). The links or "hover text" in the bottom row of each, at the right/ recent end point to the penultimate item. For example, where the middle chart last two elements should link to "Pleistocene" and "Holocene", they both link to and "hover text" to "Pliocene" (the preceding time period). I suspect it's typos in the implementation, but I'm not sure, and I don't know where templates are stored to try to examine or edit them. Aidan Karley (talk) 23:15, 9 May 2016 (UTC)

The "Proposed Precambrian" section shows more of the structure in this "timeline" template, which data looks about right (caveat, ISC 2016 has moved the base of the Cryogenian from 850 Ma to 720 Ma) but the bottom row still seems to have this off-by-one error, so I'm now more suspicious of the template. Which remains beyonf my Wiki-knowledge. Aidan Karley (talk) 23:34, 9 May 2016 (UTC)

Events in the Holocene

... Little Ice Age (stadial) causes brief cooling in Northern Hemisphere from 1400 to 1850. Following the Little Ice Age, Atmospheric CO2 levels, primarily as a result of reduced oceanic CO2 solubility where the ocean has turned from a CO2 sink to a CO2 source with the increasing temperature, rise from around 280 parts per million volume (ppmv) to the current level of 390 ppmv.

Is this a joke? HughesJohn (talk) 10:05, 6 August 2013 (UTC)

Ah, this is actualy Template:Geologic time scale. Discussion continues there. HughesJohn (talk) 11:26, 6 August 2013 (UTC)

Neozoic era

There is a mention of a neozoic era in some sources, notably Montessori education material [6][7]and Romanian Wikipedia[8]. It is absent in the US Geological Society timeline page[9], and has no mention on this (English) Wikipedia page. While most sources that recognize this era consider it to be the current era, they are divided on whether the neozoic era is a synonym of the cenozoic era[10], a term that refers to a combination of the mesozoic and cenozoic eras[11], or an era that follows the cenozoic era[12] . — Preceding unsigned comment added by Rcanand (talk • contribs) 04:18, 7 September 2013 (UTC)

Correction Needed On "Clock Representation" Graphic?

I noticed a discrepancy between when the "clock representation" graphic at the top of this page says the Hadean ends (3.8 billion years ago) and when the Hadean page ( https://en.wikipedia.org/wiki/Hadean ) says the Hadean ends (4 billion years ago). Although I know nothing about geology, I mentioned it on the Hadean page and someone said that this graphic is now outdated. Their source was https://engineering.purdue.edu/Stratigraphy/gssp/index.php?parentid=all . Hopefully we can resolve this confusing discrepancy. Paisleypants (talk) 14:35, 16 December 2013 (UTC)

Correction also needed of the date of the Cambrian Explosion. Can someone knowledgeable in graphics please change the number from "530" to "541" for the Cambrian Explosion? The clock representation is such a great visual tool for obtaining a comparative perspective and I think "541" is the presently accepted estimate (although the German version in the Wikipedia Commons Collection uses "543"; see https://commons.wikimedia.org/wiki/File:Geologische_Uhr_mit_Zeitskalen_und_Ereignissen.svg). Wish I could do it myself, but it would take me eons ... We certainly don't want the interested public to wait that long for the improved educational tool. Thank you in advance! --77.11.151.243 (talk) 13:22, 20 December 2020 (UTC)Interested reader

 Done I changed "c. 530" to "c. 540"; better not to try to be too accurate here. Peter coxhead (talk) 07:25, 22 December 2020 (UTC)

The correction is great; however, there is no recording of the change in the graphic's file history, and the correction is also not presented as a new version of the Wikipedia article. What is even more distressing is that the changed graphic is appearing down through the older versions of the Wikipedia article! George Orwell is nodding his head! It must be possible to keep older article versions including their accompanying graphics unchanged and present a corrected graphic in a new version of the article. I hope that you can do this. Thank you in advance! --78.55.204.89 (talk) 15:54, 22 December 2020 (UTC)Interested reader

Sorry, that's not how links from Wikipedia to Commons work. The change is recorded at File:Geologic Clock with events and periods.svg – look under "File history". Earlier versions of Wikipedia articles always link to the latest version of a file. Peter coxhead (talk) 20:04, 22 December 2020 (UTC)

Yes, it is very unfortunate that "that's not how links from Wikipedia to Commons work ... Earlier versions of Wikipedia articles always link to the latest version of a file" at the moment. The older graphic versions do have links (for example, https://upload.wikimedia.org/wikipedia/commons/archive/7/77/20201222072229%21Geologic_Clock_with_events_and_periods.svg), so it is possible to link up any version of the text file with the real version of its accompanying graphic. Somebody knowledgeable in computing must find the current way of doing things as very distressing as I do. The history of Wikipedia articles is something for the interested public. And the current way that Wikipedia is linking graphics to file versions changes the history of the Wikipedia articles. I ask you: is this a petty issue? I can imagine that George Orwell is snickering. 78.55.216.212 (talk) 13:56, 23 December 2020 (UTC)interested reader

Cross-link other geological periods (etc.) back to here?

Any objections if all the other related articles get cross-linked back to here? I think that would help unify these related topics. ~ J. Johnson (JJ) (talk) 19:53, 21 December 2013 (UTC)

No objections. Links are encouraged. I think you will find that most such articles have templates that already link back here, frequently from the title of the template. If you find an article without such a template, and the template is relevant, add the template. Even when a template with a link is present in an article, it is still acceptable to link from the first reasonbable location in the running text, but I would not reccommend adding text to the running text merely to create a link to this article. Since the named intervals form a hierarchy, it is often more natural to have finer-grained names link to their parents in the hierarchy. The interested reader will eventually get here by climbing through the hierachy. -Arch dude (talk) 17:59, 22 December 2013 (UTC)

I think it is good to have each interval linked back to its parent. But I also think there should be a link directly to the top (i.e., here) as the general concept. And not buried in the text, but something like a "see also" right at the top. ~ J. Johnson (JJ) (talk) 23:44, 22 December 2013 (UTC)

I do not agree. Please consider the general case. There are a great many hierarchies of articles on Wikipedia. If all such articles had "see also" links to the top of their respective articles, the articles would become cluttered. Many articles are part of multiple hierarchies, and it's not clear where the "top" of a hierarchy is. For example, This article is not the top of the "Geology" hierarchy, or the "Science" hierarchy. Should all "geology" articles have a "geology" hatnote? A "science" hatnote? A hatnote to each article in in its ancestral path? No. Wikipedia has evolved multiple mechanisms to handle these hierarchies. These include the category system and the template system. Note: I'm just one editor and my opinions have no more weight than yours. But you are suggesting a fairly major change, so you will need to get consensus before proceeding. I personally think that Wikipedia has far too many hatnotes already, so I prefer to avoid adding still more. Our goal should be to make it easy for a reader to use Wikipedia, and for me, wading through a bunch of front matter before reaching the material I need detracts from the experience. -Arch dude (talk) 04:37, 23 December 2013 (UTC)

I think you over-generalize. All of the geological "intervals" (epochs, eras, periods, series) are definitely instances of "geological time scale", whereas the latter is not an instance of "geology". To place an interval only within its parent only begs the question of where that interval is overall; one has to climb all the way out. A top link doesn't have to be a hat note; Eocene includes such a link in the text. Or if that that clutters the text too much I think it would suffice to have such a link in the infobox. ~ J. Johnson (JJ) (talk) 22:44, 23 December 2013 (UTC)

Then we are in complete agreement. This is what is said in my first reply. My second reply (the objection) was against your And not buried in the text, but something like a "see also" right at the top, which I interpreted as an obtrusive hatnote. -Arch dude (talk) 01:09, 24 December 2013 (UTC)

FWIW, I agree with the option suggested by J. Johnson. While, if there is no objection, I'll be updating the pertinent articles with recourse to the 2004 and 2012 versions of the GTS, anyone is welcome to do that particular edit. --Dracontes (talk) 15:41, 24 December 2013 (UTC)

  Ah, your objection was just to being in the form of a hatnote. Okay, I'm fine with "not a hatnote". Before Dracontes goes charging forth, I wonder if we might consider some kind of general formulation that be applied to all geological time interval articles. Something like at Eocene: "[interval] is ... a [major? minor? ??] [epoch, period, ...] in the geological time scale ...." Or? ~ J. Johnson (JJ) (talk) 21:31, 24 December 2013 (UTC)

Just so. Basically, a typical WP article (not policy, but fairly standardized when the construction is not awkward) starts with defining sentence of this type, and this is exactly what I meant by "first reasonable occurance in the running text." Of course, I would have been more helpful if I had actually said that in the first place! -Arch dude (talk) 20:51, 27 December 2013 (UTC)

Yeah, I sympathize. It's so hard to be perfect all the time. :-)

Should we run up some model lead sentences for emulation? ~ J. Johnson (JJ) (talk) 22:53, 27 December 2013 (UTC)

A few corrections

• The (controversial; see above.) picture at top right shows only non-avian dinosaurs on it's line; there is no excuse for leaving birds out in 2014. And besides, non-avian dinosaurs went extinct 66.5 mya, not 65.
• Section with table has multiple errors;
• Triassic section says that Icthyosaurs and nothosaurs are archosaurs, and that dinosaurs where the dominent land fauna. The first mistake is fairly obvious; as for the second, dinosaurs only appeared in the Late, and Croc-line archosaurs where more successful anyway.
• Cretaceous section goes with the outdated idea that birds replaced pterosaurs.
• I remember reading somewhere that grasses appeared in the Cretaceous.
• Angiosperms appeared in the Triassic.
• Shouldn't the Cretaceous section mention the K-pg event?
• Cretaceous section in general could use expantion.
• Carboniferous is the only paleozoic section to go in-depth at the epoch level; all others do period level.
• Is there seriously nothing else to say about the Pliocene and Olgiocene?
• Probably some other stuff I forgot to mention; someone else please do a second check.142.176.114.76 (talk) 12:45, 28 February 2014 (UTC)

The boundary between the Ordovician Period and the Silurian Period is 443.8 mya according to the Geologic Time Scale published by the International Commission on Stratigraphy in January 2015: http/www.stratigraphy.org/ICSchart/ChronostratChart2015-01.pdf. So the Wikipedia Geologic Time Scale should be updated. — Preceding unsigned comment added by 212.50.248.2 (talk) 13:24, 30 May 2015 (UTC)

Gabonionta to add?

In the Table of geologic time, should the http://en.wikipedia.org/wiki/GaboniontaGabonionta - "the earliest form of multicellular life" be mentioned? — Preceding unsigned comment added by 193.170.196.53 (talk) 12:21, 27 August 2014 (UTC)

Hmmm, Gabonionta. That may be a bit recent and not-fully settled work. I was checking up on it when I was working in (well, offshore) Gabon in the last couple of years. I'll check the current state of published research, but my first inclination would be to leave it for a couple of years until there has been independent work on these fossils. We don't want to do a "Schopf" on this and expose ourselves to a Brasier! Aidan Karley (talk) 15:14, 9 May 2016 (UTC)

Ooops, typo in previous comment summary. Doesn't seem to be a way to edit that though. Aidan Karley (talk) 15:16, 9 May 2016 (UTC)

Reviewed the 2010 and 2014 papers from ElAlbani et al ; I can't find evidence of strongly made arguments against their interpretation, and the data presented do seem to fulfil the necessary criteria to establish them as fossils rather than pseudo-fossils. The interpretation of them as multicellular seems a little weaker, and the assertion that they don't appear to have left descendants is also a little less solid (think of the "string-of-beads" fossil, Horodyskia . But this is plainly an active area of research. Aidan Karley (talk) 21:54, 9 May 2016 (UTC)

Lower, Middle, Upper

The current 2015 chart put out by the International Commission on Stratigraphy no longer shows the epochs as Early, Middle, and Late. They are shown as Lower, Middle, and Upper.

http://www.stratigraphy.org/ICSchart/ChronostratChart2015-01.jpg

How do you change the Wikipedia chart? Under edit mode, it doesn't show the epochs. Yet, they're still displayed in read mode.

The chart in the article is about geochronology, that is the geological ages, and uses the appropriate terms Early, Middle and Late. The ICS chart uses, and has always used as far as I know, chronostratigraphy, referring to the rock sequences themselves - see the terminology section of the article and the preamble to the chart itself. Mikenorton (talk) 17:44, 5 July 2015 (UTC)

External links modified

Hello fellow Wikipedians,

I have just modified 3 external links on Geologic time scale. Please take a moment to review my edit. If you have any questions, or need the bot to ignore the links, or the page altogether, please visit this simple FaQ for additional information. I made the following changes:

• Added archive http://web.archive.org/web/20050920105136/http://www.stratigraphy.org:80/ to http://www.stratigraphy.org/
• Added archive http://web.archive.org/web/20140530005940/http://www.stratigraphy.org/index.php/ics-chart-timescale to http://www.stratigraphy.org/index.php/ics-chart-timescale
• Added archive https://web.archive.org/web/20060716071827/http://www.stratigraphy.org/gssp.htm to http://www.stratigraphy.org/gssp.htm

When you have finished reviewing my changes, please set the checked parameter below to true or failed to let others know (documentation at {{Sourcecheck}}).

This message was posted before February 2018. After February 2018, "External links modified" talk page sections are no longer generated or monitored by InternetArchiveBot. No special action is required regarding these talk page notices, other than regular verification using the archive tool instructions below. Editors have permission to delete these "External links modified" talk page sections if they want to de-clutter talk pages, but see the RfC before doing mass systematic removals. This message is updated dynamically through the template {{source check}} (last update: 18 January 2022).

• If you have discovered URLs which were erroneously considered dead by the bot, you can report them with this tool.
• If you found an error with any archives or the URLs themselves, you can fix them with this tool.

Cheers.—InternetArchiveBot (Report bug) 11:54, 21 July 2016 (UTC)

External links modified

Hello fellow Wikipedians,

I have just modified one external link on Geologic time scale. Please take a moment to review my edit. If you have any questions, or need the bot to ignore the links, or the page altogether, please visit this simple FaQ for additional information. I made the following changes:

• Added {{dead link}} tag to http://resource.geosciml.org/sparql/isc2014
• Added archive https://web.archive.org/web/20060211234211/http://flatpebble.nceas.ucsb.edu:80/cgi-bin/bridge.pl?action=startScale to http://flatpebble.nceas.ucsb.edu/cgi-bin/bridge.pl?action=startScale

When you have finished reviewing my changes, you may follow the instructions on the template below to fix any issues with the URLs.

This message was posted before February 2018. After February 2018, "External links modified" talk page sections are no longer generated or monitored by InternetArchiveBot. No special action is required regarding these talk page notices, other than regular verification using the archive tool instructions below. Editors have permission to delete these "External links modified" talk page sections if they want to de-clutter talk pages, but see the RfC before doing mass systematic removals. This message is updated dynamically through the template {{source check}} (last update: 18 January 2022).

• If you have discovered URLs which were erroneously considered dead by the bot, you can report them with this tool.
• If you found an error with any archives or the URLs themselves, you can fix them with this tool.

Cheers.—InternetArchiveBot (Report bug) 14:20, 9 January 2017 (UTC)

Should "Major events" be removed from the "Table of geologic time"?

It seems time to push-back against adding one's favorite orogeny as a major event in the Geologic time scale#Table of geologic time, especially those that are not sufficiently major to have their own article. These and other details bloat the the table, greatly reducing its effectiveness. I note that the International Chronostratigraphic Chart this table is based on does not have "Major events", and seems all the better for that. Should "Major events" be removed?

If "Major events" is to be retained it should be only one or two major events that give the reader some overall sense of what happened when, and perhaps we need to state that nothing else should be added. Orogonies especially, as 1) they are all local, and 2) there's too many of them (see List of orogenies). But perhaps better to just delete "Major events". ~ J. Johnson (JJ) (talk) 22:07, 21 May 2017 (UTC)

I'm in favour of keeping it. I, at least, find it interesting. — Preceding unsigned comment added by EarthOcean (talk • contribs) 00:28, 20 September 2017 (UTC)

External links modified

Hello fellow Wikipedians,

I have just modified 4 external links on Geologic time scale. Please take a moment to review my edit. If you have any questions, or need the bot to ignore the links, or the page altogether, please visit this simple FaQ for additional information. I made the following changes:

• Added archive https://web.archive.org/web/20091209020034/http://www.stratigraphy.org/upload/bak/chron.htm to http://www.stratigraphy.org/upload/bak/chron.htm
• Corrected formatting/usage for http://flatpebble.nceas.ucsb.edu/cgi-bin/bridge.pl?action=startScale
• Added archive https://web.archive.org/web/20091229003212/http://www.stratigraphy.org/upload/ISChart2009.pdf to http://www.stratigraphy.org/upload/ISChart2009.pdf
• Added archive https://web.archive.org/web/20040623025505/http://www.stratigraphy.org/geowhen/ to http://www.stratigraphy.org/geowhen/

When you have finished reviewing my changes, you may follow the instructions on the template below to fix any issues with the URLs.

This message was posted before February 2018. After February 2018, "External links modified" talk page sections are no longer generated or monitored by InternetArchiveBot. No special action is required regarding these talk page notices, other than regular verification using the archive tool instructions below. Editors have permission to delete these "External links modified" talk page sections if they want to de-clutter talk pages, but see the RfC before doing mass systematic removals. This message is updated dynamically through the template {{source check}} (last update: 18 January 2022).

• If you have discovered URLs which were erroneously considered dead by the bot, you can report them with this tool.
• If you found an error with any archives or the URLs themselves, you can fix them with this tool.

Cheers.—InternetArchiveBot (Report bug) 10:12, 26 July 2017 (UTC)

External links modified

Hello fellow Wikipedians,

I have just modified 3 external links on Geologic time scale. Please take a moment to review my edit. If you have any questions, or need the bot to ignore the links, or the page altogether, please visit this simple FaQ for additional information. I made the following changes:

• Added archive https://web.archive.org/web/20050418090602/http://rst.gsfc.nasa.gov/Sect2/Sect2_1b.html to http://rst.gsfc.nasa.gov/Sect2/Sect2_1b.html
• Added {{dead link}} tag to http://www.chronos.org/
• Added archive https://web.archive.org/web/20051111150720/http://www.nmnh.si.edu/paleo/geotime/index.htm to http://www.nmnh.si.edu/paleo/geotime/index.htm
• Added archive https://web.archive.org/web/20110714173934/http://www.newsciencelessons.com/geology_lesson_plans.html to http://www.newsciencelessons.com/geology_lesson_plans.html

When you have finished reviewing my changes, you may follow the instructions on the template below to fix any issues with the URLs.

This message was posted before February 2018. After February 2018, "External links modified" talk page sections are no longer generated or monitored by InternetArchiveBot. No special action is required regarding these talk page notices, other than regular verification using the archive tool instructions below. Editors have permission to delete these "External links modified" talk page sections if they want to de-clutter talk pages, but see the RfC before doing mass systematic removals. This message is updated dynamically through the template {{source check}} (last update: 18 January 2022).

• If you have discovered URLs which were erroneously considered dead by the bot, you can report them with this tool.
• If you found an error with any archives or the URLs themselves, you can fix them with this tool.

Cheers.—InternetArchiveBot (Report bug) 05:26, 13 October 2017 (UTC)

Origin of eons

Perhaps I'm mistaken, or perhaps the books I was reading were mistaken, but when I went through my geology/paleontology phase as a kid, there were Proterozoic, Paleozoic, Mesozoic, and Cenozoic eras. I don't recall reading about eons at all. I'm now seeing that, compared with the arrangement I recall, the Proterozoic has been promoted to an eon, while the other three eras as I knew them have been assigned to a new eon, the Phanerozoic.

But wait—now I see that I'm not completely imagining it: the opening graphic in this article, the one with the circular diagram, appears to have been designed by someone who put the Paleozoic, Mesozoic, and Cenozoic on the same footing as the Proterozoic.

If there has indeed been an evolution (pun intended) in the nomenclature at some point in the last 50+ years, with the introduction of eons and the breakdown of the geological time scale into greater detail, I wonder whether someone can add an explanation of those developments in the History section of the article, for the benefit of those who, like me, will wonder what the heck is going on. You know, the same way that the article on Pluto and the Outer planets explain that Pluto was considered a planet despite not being counted as one now. Largoplazo (talk) 17:51, 5 December 2017 (UTC)

Galactic Rotational Cycles and the Age of the Earth

The Age of the Earth can be estimated from Galactic Rotational Cycles of 186.598 Million Years per Cycle Plus 66.043 +/- 0.011 Million Years since the Chicxulub Impact Event. That is (24.0 X 186.598) + 66.043 +/- 0.011 Ma = 4478.352 + 66.043 = 4544.395 Ma, which we will round to 4544.4 Ma. This is inside the range of 4540 Ma to 4550 Ma. As a cross check we can use the recession rate of the Moon away from the Earth which has a net value of 38.2 mm per Year. It is based on a tripple ratio. The Change in the Mass divided by the mass of the Earth-Moon system is proportional to the change in the distance divide by the distance, which is proportional to the change in the age divided by the total age (in parts per billion). For the age there is a two in the denominator (Final condition minus Initial condition divided by 2 ). The denominator is 9.0888 E 9 , so the Age is 9.0888 E 9 / 2 = 4.5444 E 9 = 4544.4 Ma. I would suggest consulting the wall chart called: A CORRELATED HISTORY OF THE EARTH, and look at the Author's Theory near the bottom, right of center. He uses 186 Ma, but 24 x 186 + 66 = 4530 Ma which is a bit short of the required time to get the full age. A Better simplified estimate is 186.6 X 24 + 66 = 4544.4 Ma. The Moons age is less than the Earth's Age by more than one Galactic Rotational cycle. 63.225.17.34 (talk) 15:14, 4 June 2018 (UTC)

Ice Ages are important

10¹⁰

Precambrian

" "

Hadean

Archean

Proterozoic

Phane

Eo-

Paleo-

Meso-

Neo-

Paleo-

Meso-

Neo-

P

M

C

9

8

7

6

5

4

3

2

1

10⁹

Proterozoic

Phanerozoic

Neoproterozoic

Paleozoic

Mesozoic

Cenozoic

Tonian

Cryogenian

Ediacaran

Cambr

Ordov

Si

Devon

Carbon

Permi

Trias

Juras

Creta

P-gene

9

8

7

6

5

4

3

2

1

Cloud forest (talk) 16:33, 25 September 2018 (UTC)

unsourced claim that contradicts itself

For example, the lower Jurassic Series in chronostratigraphy corresponds to the early Jurassic Epoch in geochronology.[2] The adjectives are capitalized when the subdivision is formally recognized, and lower case when not; thus "early Miocene" but "Early Jurassic."

The article Miocene chaotically uses both upper- and lowercase and Early Miocene uses only uppercase. --2001:999:50:E0C6:F5:2D89:6AF3:8C8D (talk) 09:21, 1 September 2019 (UTC)

Newspapers not authoritative sources for science

A citation of The Guardian for a point concerning the Anthropocene prompts me to remind everyone that newspapers are not the best sources for information about scientific matters. While many newspapers can be considered "reliable" (as in WP:RS) for ordinary news, in the scientific context they are generally not authoritative. And we do have better, more authoritative, secondary sources in the news and comment pieces in journals such as Science and Nature, especially for news regarding the Anthropocene. ♦ J. Johnson (JJ) (talk) 20:40, 16 September 2019 (UTC)

Uncited vague statement

"This discrepancy is caused by the lack of action in the first three eons (or supereon) compared to our’s (the Phanerozoic)" This line is very vague and not backed up by science. The pre-Cambrian is full of significant geological events. A key reason for the imbalance in the Phanerozoic and pre-Cambrian scales is the difficulty in defining a Global Boundary Stratotype Section and Point for the pre-Cambrian. Within the Phanerozoic this is often tied to a biostratigraphic event. I don't think this line is really necessary and the preceding sentences could also use some cleaning up. I would like to discuss this prior to changing it, in order to get the opinion of other editors as to what information they would find more useful here. Jarred C Lloyd (talk) 15:42, 30 July 2020 (UTC)

It doesn't sound very encyclopedic. There is, however, some indications that there was less tectonic activity through large parts of the Precambrian than has been the case during the Phanerozoic. APW curves suggest that most of the Proterozoic had limited orogenic activity (aka "the Boring Billion"), with small-scale "jostling" around a single supercontinent rather than cycles of "break-up" and "collision". Your point regarding lack of biostratigraphic markers is undoubtedly correct, although many of the subdivisions in the Phanerozoic can be tied to specific tectonic events. Mikenorton (talk) 16:32, 30 July 2020 (UTC)

If the sentence is not changed or removed for geological or source reference citation reasons, it should still be changed because of WP:PRONOUNS. GeoWriter (talk) 10:55, 31 July 2020 (UTC)

While general lithospheric and evironnmental stability has has been suggested in the past and the time ~1.7 Ga – 0.75 Ga has been dubbed the "Boring Billion", more recent work is suggesting that it may not have been quite so boring. As for the Piper (2018) I'm not sure I agree with the findings of it. Obviously there are mulitple views on the timing of the transition to plate tectonics from a stagnant lid, I am more in agreement with an older transition and find it hard believe a conclusion of only one supercontinent, even from just 1 Ga to present based on studies that utilise multiple datasets (palaeomag, rock records, geochemistry) .

My point of this though is I do think that the sentence in question should be revised to better reflect what was trying to be highlighted, the discrepancy in the size of the table for the Phanerozoic vs Precambrian. Which is based more on the difficulty tying the Precambrian rock record to a GSSP due to various factors, one being the difference in biological life and its preservation, but also the often fragmented and ill preserved Precambrian successions, particularly the Neoproterozoic. Jarred C Lloyd (talk) 13:47, 1 August 2020 (UTC)

I've had a go at revising it (only took me a year), but added a "citation needed" tag, as it's still just supposition. Mikenorton (talk) 20:48, 31 July 2021 (UTC)

Definitely reads more truthful, and I've been so busy lately I'd almost forgotten about this. Thanks for doing the edit. This paper might be somewhat suitable as it highlights the past issues and difficulties in obtaining chronostratigraphic units for pre-Cambrian time. It's an OA article, the introduction is the most useful part in the context of the original issue. I can add this as the citation if you think it addresses the issue at hand. Jarred C Lloyd (talk) 07:57, 5 August 2021 (UTC)

References

Anthropocene

"Others say that humans have not even started to leave their biggest impact on Earth, and therefore the Anthropocene has not even started yet." - which others have said that? This statement is currently unreferenced and should perhaps be removed if a ref can't be applied. Cheers Geopersona (talk) 16:39, 30 July 2020 (UTC)

Yes indeed. Though, I do remember seeing it in a news article some time back. i will try to scour it out. Regards, PNSMurthy (talk) 05:35, 4 August 2020 (UTC)

Rocks

Which statement is true about history of earth 2601:7C0:C080:1BE0:4C24:3B1A:8205:4F56 (talk) 22:59, 29 January 2022 (UTC)