Talk:Cryogenian

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edit·history·watch·refresh Stock post message.svg To-do list for Cryogenian:

Here are some tasks awaiting attention:
  • Article requests : Lifeforms in Cryogenian, Subdivisions of Cryogenian, Nonglacial periods.
  • Update : Fossils
Priority 3

Discussion[edit]

(William M. Connolley 18:43, 22 Sep 2004 (UTC)) I've merged this with Varanger glac. In the course of that I removed:

However, carbon isotope analysis indicates that several worldwide glaciations may have occurred.

Carbon dating doesn't go back the far. I think. Radiocarbon dating says 50kyr.

The carbon analysis here isn't C-14 decay, actually, it's calculating the concentrations of stable C-13 in sediments. The more carbon that's locked away in sediments means that there's fewer greenhouse gases left to warm the atmosphere.

The Caltech link is broken. RandomCritic 16:51, 23 November 2006 (UTC)

Me being hyperprecize: the carbon analysis is [13C:12C] balance, natural isotopic balance implying inorganic origin, deviation from natural implying organic origin. Organic origin implies no glaciation, inorganic origin may imply glaciation or some other harsh conditions for life. Rursus 21:40, 27 December 2006 (UTC)

Varanger??[edit]

As much as I've experienced, there seem to be no scientific consensus to what Varanger and Marinoan refers. I've seen Varanger referring to a short glaciation around ~570 Ma, which was otherwise called Gaskier's. I may be wrong however... Rursus 21:43, 27 December 2006 (UTC)

The term Varanger is now depreciated. It referred to any or all of the glaciations in the Snowball Earth period. Verisimilus T 22:52, 9 May 2007 (UTC)
Adelaide Geosyncline - There is a table with a time-scale. I'm guessing they are terms used locally to define when those formations where depositied. The younger Marinoan event occured at the end of the Cyrogenian, by definition, as the overlying Nuccaleena formation dolomite defines the start of the Edicaran. —Preceding unsigned comment added by 139.130.43.94 (talk) 04:43, 30 January 2009 (UTC)

...Oh, dear...[edit]

I think we need a massive rewrite of this article: It's one of the most layman-unfriendly articles I've seen, not only failing to explain terms, but often using an obscure geological term where a perfectly good common-language term is available, such as use of Ma for dates, "tillage" for glacial deposits, etc. Adam Cuerden talk 20:42, 21 May 2007 (UTC)

I've had a go at the first paragraph, but am not really sure what to do after that.... Adam Cuerden talk 21:02, 21 May 2007 (UTC)
I have made a pass over both paragraphs. I think the geological terms are fine since it's an article on geology, but have tried to give some contextual cues and to streamline the sentence structure. --Reuben 16:18, 18 September 2007 (UTC)
On the same subject i don't know if everyone knows what "circa" means... I don't think Latin expressions would help anyone... —Preceding unsigned comment added by Sinekonata (talkcontribs) 23:18, 3 October 2009 (UTC)

Start 850 or 750??[edit]

Actually, the Subcommission on Neoproterozoic Stratigraphy of ICS says 750 million years ago, in it's annual report of 2006. Said: Rursus 22:54, 28 October 2007 (UTC)

I think these link are deads. In 2015, ICS updated to 720 Mya, See [1] Red Planet X (talk) 18:15, 27 February 2016 (UTC)

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And shouldnt the end be at the start of the Ediacaran at ~635 Ma rather than 630? Although there is no exact dating on the Australian succession it is more correct to say 635 than 630 Ma. I will change it. —Preceding unsigned comment added by 130.238.7.35 (talk) 12:59, 24 March 2010 (UTC)

Land Plants[edit]

Would this research be important to include in this article, since it states one of the possible causes of glaciations? --Artman40 (talk) 10:50, 5 April 2009 (UTC)

Sponges[edit]

According to recent research, sponge fossils have found in Cryogenian period. When we can add that information? --Artman40 (talk) 17:16, 5 April 2009 (UTC)

 Done I just added the sponge fossils to the template. --Tobias1984 (talk) 10:49, 7 December 2012 (UTC)

Hey, this whole sponge-origin thing is really quite hazy, you know?

Contents in wrong place[edit]

{{help}} There is an error which I cannot sort out which puts the contents in the wrong place. Can an expert deal with this? Dudley Miles (talk) 21:21, 8 March 2012 (UTC)

I've fixed it by splitting the intro into the intro and a second section and forcing a table of contents in between. I called it "ratification" because that was the first key word I saw, so there is probably something better to call it--Jac16888 Talk 21:28, 8 March 2012 (UTC)
{{help}} Thanks for sorting this but there is still a problem which I do not understand. There is now a duplicate references heading on the right. (I have moved entries in references which belonged in further reading but this did not make any difference.) Dudley Miles (talk) 21:55, 8 March 2012 (UTC)
A newbie had messed up a template transcluded onto the page. I've fixed that. Reaper Eternal (talk) 22:13, 8 March 2012 (UTC)

Mismatches between graphic and Climate text[edit]

The Climate section's text speaks of two glaciations (Sturtian and Marinoan) whereas the graphic shows 3 glaciations (Kaigas being the third), and the Sturtian dates disagree (720 to 700 million years ago in the graphic, 750 to 700 million years ago in the text, which thus overlaps the Kaigas in the graphic). As an ignorant layman, I don't feel competent to try to fix any of this.Tlhslobus (talk) 08:49, 7 December 2012 (UTC)

Hi Tlhslobus! Thank you for bringing attention to this problem. I moved the Kaigas glaciation to the notes. According to the sources I could find it is a really enigmatic glaciation. Duration and global extent are still very uncertain. It also seems that the duration that was given in the template previously was not the duration of the glaciation, but the estimated time interval in which the glaciation is thought to have happened. I will try to fix the text as soon as possible. --Tobias1984 (talk) 10:47, 7 December 2012 (UTC)

Controversy?[edit]

These 'snowball earth' events are the subject of much scientific controversy

Is this still true? Viriditas (talk) 02:02, 4 January 2013 (UTC)

Not an expert on the subject but there is no doubt that these ice ages happened. I think the degree of glaciation is controversial. Maybe the wording should be changed to this. --Tobias1984 (talk) 08:23, 4 January 2013 (UTC)

Map?[edit]

I am trying alot of ways to get an image of Rodinia during the Cryogenian period. The only one I found was this: http://www.scotese.com/precambr.htm. However I need someone (or an admin) to get this image displayed as it is the only valid paleogeography image during the Cryogenian period. MarioProtIV (talk) 16:47, 4 January 2014 (UTC)

there is no information about the copyright of the map. Do a google image search and see if you can find where this came from. The chances are that we will need a redrawn map so as to be free. Graeme Bartlett (talk) 21:09, 4 January 2014 (UTC)
As I said, the page I got it from is this: http://www.scotese.com/precambr.htm. But do I have to upload it to Wikimedia in order to get it uploaded here? --MarioProtIV (talk) 16:42, 5 January 2014 (UTC)

Cryogenian's base changed from 850 Mya to 720 Mya[edit]

Can anyone explain why the ICS changed this?

Additional remark: "The Sturtian glaciation persisted from 750 to 700 million years ago." The graph on the right hand side shows the Sturtian lasting from 720 to 660 million years ago. I detect a contradiction there.

Martin — Preceding unsigned comment added by 193.26.252.253 (talk) 17:17, 17 August 2015 (UTC)

Cryogenian Base changed to 720 MYA[edit]

I think I have found the reason.

According to "Age constraints on Precambrian glaciations and the subdivision of Neoproterozoic time" there were four glaciations during the Cryogenian.

Kaigas (poorly constrained to between 770 and 735 Ma) Sturtian (well constrained to c. 715 - 680 Ma) Marinoan (well constrained to 660 - c. 635 Ma) Gaskiers (extremely well constrained to c. 585 - c. 582 Ma)

The youngest, Gaskiers has been placed in the Ediacarian. They wanted the two biggest and most important glaciations to constitute the Cryogenian, so they proposed a new GSSP for the base of the Cryogenian to be placed between the end of the Kaigas and the beginning of the Sturtian. Including the Kaigas would have been difficult because it is so poorly constrained and probably not even global in extant. — Preceding unsigned comment added by Martin3003 (talkcontribs) 21:10, 24 September 2015 (UTC)

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