Talk:Geologic time scale

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Circular scale, ugh...[edit]

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. (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. (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."..... (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.... (talk) 16:43, 28 January 2013 (UTC)


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[edit]

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.

Earth Clock 2.gif

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)

Geologic clock.jpg

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 [[1]]. 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 (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[edit] 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 (talkcontribs) 21:22, 25 March 2009 (UTC)

Time scale changes[edit]

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[edit]

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

Help requested[edit]

In watching recent changes I came across this edit: [2]. 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"[edit]

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. -- (talk) 22:59, 26 September 2009 (UTC)

Galactic Year[edit]

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 - material[edit]

Content from / 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 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[edit]

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[edit]

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[edit]

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):

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[edit]

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[edit]

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 ( and the Kaapvaal craton page ( 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 (talk) 15:48, 22 August 2010 (UTC)

Terminology: Late/Upper[edit]

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. (talk) 11:40, 1 September 2010 (UTC)

A comparative geological timescale[edit]

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[edit]

The spiral graphic ( 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 --Furrfu (talk) 19:15, 8 September 2011 (UTC)

Letter designations for periods etc[edit]

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[edit]

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 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. ( 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 (talkcontribs) 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. HrafnTalkStalk(P) 03:09, 31 December 2010 (UTC)

So here is one argument that is against the geologic time scale. 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. HrafnTalkStalk(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. HrafnTalkStalk(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[edit]

"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)


"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. (talk) 05:10, 5 December 2011 (UTC)

supereon: when? where? who?[edit]

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 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[edit]

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 (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[edit]

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. HrafnTalkStalk(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[edit]

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[edit]

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)[edit]

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[edit]

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: [3] 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"?[edit]

The clock representation diagram and the caption uses the term "Ga", which is never defined in the text. — Preceding unsigned comment added by Drozdyuk (talkcontribs) 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)


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[edit]

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. (talk) 11:55 10 April 2013 (UTC) 7:55am 04/10/2013 EDT. The following four timelines show the geologic time scale. The first shows the entire time from the formation of the Earth to the present, but this compresses the most recent eon. Therefore, the second scale shows the most recent eon with an expanded scale. The second scale compresses the most recent era, so the most recent era is expanded in the third scale. The third scale compresses the most recent period, so the most recent period is expanded in the fourth scale.
Siderian Rhyacian Orosirian Statherian Calymmian Ectasian Stenian Tonian Cryogenian Ediacaran Eoarchean Paleoarchean Mesoarchean Neoarchean Paleoproterozoic Mesoproterozoic Neoproterozoic Paleozoic Mesozoic Cenozoic Hadean Archean Proterozoic Phanerozoic Precambrian
Cambrian Ordovician Silurian Devonian Carboniferous Permian Triassic Jurassic Cretaceous Paleogene Neogene Quaternary Paleozoic Mesozoic Cenozoic Phanerozoic
Paleocene Eocene Oligocene Miocene Pliocene Pleistocene Holocene Paleogene Neogene Quaternary Cenozoic
Gelasian Calabrian (stage) Pleistocene Pleistocene Pleistocene Holocene Quaternary
Millions of Years

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. (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[edit]

... 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[edit]

There is a mention of a neozoic era in some sources, notably Montessori education material [4][5]and Romanian Wikipedia[6]. It is absent in the US Geological Society timeline page[7], 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[8], a term that refers to a combination of the mesozoic and cenozoic eras[9], or an era that follows the cenozoic era[10] . — Preceding unsigned comment added by Rcanand (talkcontribs) 04:18, 7 September 2013 (UTC)

Correction Needed On "Clock Representation" Graphic?[edit]

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 ( ) 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 . Hopefully we can resolve this confusing discrepancy. Paisleypants (talk) 14:35, 16 December 2013 (UTC)

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

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[edit]

  • 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. (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/ So the Wikipedia Geologic Time Scale should be updated. — Preceding unsigned comment added by (talk) 13:24, 30 May 2015 (UTC)

Gabonionta to add?[edit]

In the Table of geologic time, should the - "the earliest form of multicellular life" be mentioned? — Preceding unsigned comment added by (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[edit]

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.

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)

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