Talk:Precambrian

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I have reverted the page to remove the comment "Because it makes up roughly seven-eights of the earth's history, reffering to it as a singular time period is misleading." From the opening paragraph. If there is a debate about whether it ought to be called a 'time period' or not, then that ought to be mentioned in the article (with opposing views, if there are any, mentioned) it has no place in the opening paragraph, which is merely a summary of what the article is about. Cheers --Monk Bretton 16:52, 15 Feb 2005 (UTC) (PS there is only on f in referring).

I understand. bad idea.vvv

64

Copyvio

The section labelled Precambrian era is a cut and paste job from the Columbia Electronic Encyclopedia.[1] I'll remove it. Matt 16:27, 18 February 2006 (UTC)[reply]

other contributions by Megaman1188

http://www.nps.gov/blca/webvc/geo_pre.htm probably PD-usgov (yes, sitenotice says so.)

The former link is copyrighted, but the latter is in public domain because it is a governmental source and no copyright is explicitly mentioned on the page. I'm not familiar with the Columbia Encyclopedia, but I suspect its information copied from the National Park website. Therefore the text probably didn't violated copyright. However, Wikipedia is not a public domain text dump, so considerable rewriting is needed before the text could be readded. (PS. I fixed Megaman1188's contributions link.)--Jyril 19:19, 18 February 2006 (UTC)[reply]

oldest rocks

An edit from April 26th of this year correctly cites some research on zircon crystals from 4400 million years ago. But attributing that age to existing "rock beds" (identified as a little older than 3800 Ma in the prior edit) is somewhat misleading, because the zircons are detrital -- they're grains that eroded out of pre-existing rocks. Those older rocks no longer exist, only the zircons do, so the oldest existing rock beds still only date to around 3800 Ma. I'll clarify this in the paragraph about the Hadean Eon. Cephal-odd 17:03, 26 December 2006 (UTC)[reply]

Age

It says that earth is 4.5 million years old here, however I usualy seeit as 4.5 billion years old someone please clarify and correct if needed.

It says 4500 million years, which is the same as 4.5 billion - if there is a place "4.5 million" is used, please point it out. Thanks. Cheers Geologyguy 01:15, 3 March 2007 (UTC)[reply]

typo?

I might just be really ignorant, but in the opening paragraph there seems to be a terrible typo... the evolution of abundant macroscopic hard-shelled fossils. I didn't know that fossils could evolve ??? --DragonGuyver 04:03, 8 March 2007 (UTC)[reply]

Fixed. Thanks. Geologyguy 04:05, 8 March 2007 (UTC)[reply]

Smithsonian (AP article)

The Associated Press ran an article today about a fifth-grade student finding a mistake made by the Smithsonian that said the "Precambrian" was an "era". Already a couple of people have tried adding copies of the AP article to Precambrian. May I point out that articles on outside news sources are copyright those news sources. We can link to those sources, and cite them as references, but we should not copy them. See Wikipedia:Copyrights. I'm also unconvinced this event (as interesting as it may be to hear about) is relevant to the Wikipedia article on Precambrian. As described in the intro, it's "an informal name." If someone gets it wrong -- even an organization as important and respected as the Smithsonian -- that's not an earthshaking event. I'm posting here in order to open discussion as to whether it should be mentioned at all. I submit that if it is mentioned, it should be mentioned briefly (not giving the whole detail of the article) and not in the intro (which is supposed to give particularly essential information). (Note: For two of the news sites that contains the article, see here and [2].)-- Why Not A Duck 22:03, 3 April 2008 (UTC)[reply]

I think that we should put it in. perhaps we could create a new section, such as "references to Precambrian in popular culture". i'm sure there might be other examples and instances? --Steve, Sm8900 (talk) 22:21, 3 April 2008 (UTC)[reply]

I think it is absurdly trivial and does not belong here at all. Perhaps in an article on Newsworthy accomplishments of 5th graders, but not here. It contributes nothing at all to understanding of the subject of the article. Cheers Geologyguy (talk) 22:58, 3 April 2008 (UTC)[reply]

I don't think it even merits a brief mention. Bcostley (talk) 23:12, 3 April 2008 (UTC)[reply]

Totally irrelevant here, this isn't wikitabloid. And as for "references to Precambrian in popular culture" - such sections are usually just absurd piles of trivia - don't need 'em. Vsmith (talk) 23:23, 3 April 2008 (UTC)[reply]

Precambrian Z

What are Precambrian Z rocks? This term is introduced without a link or explaination. WilliamKF (talk) 18:48, 30 November 2008 (UTC)[reply]

This was a scheme set up by the USGS (James, H. L. 1972. Subdivisions of Precambrian: an interim scheme to be used by U. S. Geological Survey. Amer. Assn. Petrol. Geol., 56, pp. 1128-1133) as an interim measure. It was superceded fairly soon afterwards by the IGC and doesn't seem to have been used much, so probably not worth mentioning IMO. Mikenorton (talk) 23:35, 30 November 2008 (UTC)[reply]

supereon?

Should we call the Precambrian a "supereon"? The term may be out there, but doesn't look like many stratigraphers use it to refer to the Precambrian. It's more common to speak informally of "Precambrian time". Moreover, some geologists have suggested a Geozoic supereon that overlaps considerably with the Precambrian. —Preceding unsigned comment added by Cephal-odd (talk • contribs) 17:38, 12 September 2009 (UTC)[reply]

era?

does this even matter? The Precambrian has sometimes been referred to erroneously as an "Era", which is a subdivision of an eon. why is this here?

eon(s) Precambrian EON is comprised by THREE other EONs ? (Hadean, Archaean and Proterozoic EONS) Next EON is the Phanerozoic, but it is comprised of three ERAs (Paleozoic, Mesozoic and Cenozoic ERAs)

So, like an Eon is comprised of Eras and an Era is comprised of Periods... and Periods are comprised of Epochs... In this case it seems the Precambrian EON is comprised of three other EONS; followed by a fourth EON the Phanerozoic? Bhug (talk) 20:54, 2 November 2009 (UTC)[reply]

I have removed the word 'period' after one instance of 'Precambrian' in this article. The Precambrian is also presented elsewhere in the article (and rightly, I would assert) as a 'supereon' and it is then stated to be divided into various eons. The accompanying geologic table has it as an 'eon'. The term 'Precambrian' is an awkward one for which a single appropriate word denoting 'interval of geologic(al) time' is hard to find and which, as a result is abused. It is, so far as I'm aware, the sole example of a 'supereon' but is more often referred to as a 'period' (or indeed an 'eon') - both these terms being used in the non-technical sense. This article more than any other ought to address this issue.

I have edited many Wikipedia pages replacing 'era' with period' when referring to the Jurassic, Cambrian etc etc and sometimes replacing 'period' with 'era' when referring to the Mesozoic etc but when it comes to Precambrian, it is difficult to know what to do for the best. I have tried supereon (with the wikilinking square brackets to provide the uninitiated with an idea as to what a supereon is) but often the popular (but technically inaccurate) words 'period or 'era' seem to fit better (stylistically at least) and I have guiltily let them be. Comment welcome! cheers Geopersona (talk) 07:10, 12 December 2010 (UTC)[reply]

What percentage of geologic(al) time does the Precambrian represent?

If we're settled on the Cambrian starting 542 million years ago then we need to ask when we consider geologic(al) time to have started. The article Age of the Earth would suggest we go for 4567 million years ago. That leaves us with a Precambrian supereon extending over some 4025 million years. If we do the math(s) then that gives us figure of 88.1% of all of geologic(al) time being constituted by the Precambrian - neither the 85% nor the 87% figure which have appeared on this page recently. Anyone care to offer up a different form of reasoning? thanks Geopersona (talk) 20:04, 20 December 2010 (UTC)[reply]

Help requested to correct format errors

I reversed an IP user's edit which appeared to me to be an error or vandalism, and I appear to have introduced some Skype formatting text into the article (see reference 9, Bleeker). I don't know how this happened and I don't seem to be able to correct it. Could someone else who watches this page (and who doesn't have Skype toolbar installed) please remove this extra text? I'm reluctant to keep trying myself in case I merely add more spurious formatting to the article. Sorry for the inconvenience. Thanks, Hallucegenia (talk) 16:44, 23 December 2010 (UTC)[reply]

Prediction

"It seems likely that it will eventually be replaced by the preferred terms Proterozoic, Archaean, and Hadean, and become a deprecated term. (See geologic time scale.)"

I removed this, since we shouldn't be predicting future events. I do think though, that we need to include something along these lines. Can anyone find a source for it happening already, or even just that these terms are preferable?--78.151.188.237 (talk) 20:41, 2 January 2011 (UTC)[reply]

Pangea animation

The animation above the infobox shows the break-up of the pangean super-continent to form the seven continets we have today. It is very nice, but since pangea wasn't formed until the Permian period, 299 – 251 million years ago, it isn't relavent. Could someone find something more apropriate? 81.187.148.35 (talk) 11:33, 2 February 2011 (UTC)[reply]