This article is about one of the key tools of palaeoclimatology. Ice cores contain an extraordinary amount of information about past environments. I am not an expert on this topic, but have done a fair amount of reading and I think the article covers the ground fairly thoroughly, and is ready for FAC.
Mike Christie (
talk -
contribs -
library) 16:26, 26 August 2017 (UTC)reply
Support on prose per my
standard disclaimer. Well done. As always, feel free to revert my copyediting.
These are my edits. - Dank (
push to talk) 23:14, 26 August 2017 (UTC)reply
Support Comments by Pbsouthwood
A fascinating read, and accessible to an ordinary engineer (can't speak for the general public). A little heavy going towards the end at a single sitting, but my eyes get tired after a while when nitpicking. I also spent a bit of time referring to linked material, and noticed a few places where extra links would be nice if available, otherwise some explanation would help. • • •
Peter (Southwood)(talk): 12:18, 27 August 2017 (UTC)reply
Yes, it's very commonly used. The website is at
eastgrip.org, for example, and you can see most of their pages introduce the acronym and then use it for the rest of the page.
Mike Christie (
talk -
contribs -
library) 11:13, 27 August 2017 (UTC)reply
does not become denser with additional pressure - Why, then, is there a crystal structure change at about 1500m?
I've cut this, since I can't find an unequivocal statement that it is the case; the pages I was using to source this discuss the thinning but never explicitly say that it doesn't get denser. I think it's probably
WP:OR to make the statement, and it's probably technically not true since there must, as you say, be at least a slight difference for there to be a crystal structure change. When brittle ice relaxes there is no significant visible change in its volume, so the density can't change by more than a tiny fraction; the point I was trying to make was that the major changes in density are with the transition from snow to firn to ice.
Mike Christie (
talk -
contribs -
library) 11:14, 27 August 2017 (UTC)reply
... slowly flow outwards, thinning as they do so How is the rate of flow distributed over depth? I assume there is some variation.
Yes; there's a simplified diagram in Alley that shows the fastest flow at the top; this is because the top layers do the most thinning so they must be flowing faster. The details are apparently quite complex, and Alley glosses over them; I think I have more details in another source but I felt this was too much detail for this article. Perhaps
ice sheet could cover it in more detail.
Mike Christie (
talk -
contribs -
library) 11:15, 27 August 2017 (UTC)reply
I have added a see also link to
Ice-sheet dynamics, which doesn't say much at present, but it is where the information should be. Done. • • •
Peter (Southwood)(talk): 15:25, 27 August 2017 (UTC)reply
An ice core is a vertical column through an ice sheet which provides a sample of each layer of ice, - It was a bit of a surprise to see this in the penultimate paragraph of this section. Basically this is the definition. I would have expected to see it at one of the first statements about ice cores, possibly even in its own section, possibly the first section. Is an ice core always vertical? Perhaps all the information about ice sheets should be grouped together, and a separate section or subsection on what a core is.
I see your point, but I'm not sure what the best thing to do about it would be. The reason for that section's structure is that an ice core, and the reasons for retrieving one, aren't comprehensible without knowing about ice sheets and how they are formed. The sentence explaining what an ice core is naturally come after the description of ice sheets, not before. I was hoping that the lead would serve to give the background necessary for this section to seem reasonable. Would it work to move this sentence, edited somewhat, up to start the section? And ice cores are not always perfectly vertical, though they are generally meant to be so; the current EastGRIP core deviated substantially from vertical over this summer and effort was spent to return it to vertical.
Mike Christie (
talk -
contribs -
library) 15:49, 27 August 2017 (UTC)reply
It works well for me. On rereading I think that the 3rd from last paragraph of this section (starting "Cores are often drilled...") would be better as the last paragraph, as this keeps all the physical information about the ice sheet together. If you don't think so, no problem. • • •
Peter (Southwood)(talk): 10:25, 28 August 2017 (UTC)reply
I have been trying to find out exactly which phase the cubic ice below 1500m represents. Do you have access to the relevant pages of Alley? The phase diagram in
Ice and associated descriptions is not helping me.
I've wondered about that too, but have not seen an answer in the refs so far. Alley has no more information than I put in the article, but he cites
this paper, which has further refs. Let me know if you think there should more about this in the article.
Mike Christie (
talk -
contribs -
library) 15:58, 27 August 2017 (UTC)reply
I read the article linked above. It makes no mention of cubic crystal ice, just type II air clathrates which occur in a depth zone around 1500m, where apparently they are relatively stable and presumably have a lower energy state than hexagonal ice (Ice Ih) with bubbles. The clathrate has a cubic structure and higher compression resistance than gas bubbles in ice at higher pressures, so the bubbles and hex ice reform at greater depths. The brittle zone is where the clathrates are, and when they decay after decompression. the ice may develop microscopic cracks. Apparently the clathrate structure is slow to form and decay. The article on
Nitrogen clathrate has some of this background.• • •
Peter (Southwood)(talk): 19:33, 27 August 2017 (UTC)reply
Perhaps mention in this section that the clathrate zone reverts to hex ice again at greater depths, then when one gets to the section on brittle ice it would be clearer. • • •
Peter (Southwood)(talk): 10:25, 28 August 2017 (UTC)reply
The paper linked above doesn't say that, as far as I can see; it talks about hexagonal inclusions. I got the impression that the structure of the ice below the brittle zone wasn't well understood, so I've avoided being specific. Did you have a particular part of that paper in mind as giving additional details?
Mike Christie (
talk -
contribs -
library) 09:38, 29 August 2017 (UTC)reply
Since I wrote this I've read Uchida et al. (1994), now cited in the article, which makes things clearer. I think the text I added to the brittle zone section may address this.
Mike Christie (
talk -
contribs -
library) 10:15, 29 August 2017 (UTC)reply
Coring:
What is a wireline? (a wikilink would do) Is it the same as a cable suspended drill?
How does a cable suspended drill power the cutting head? how does it lock to the ice to allow torque to be exerted at the cutting head? (a wikilink would do)
When samples are analyzed, an outer layer may be removed to reduce the risk of contamination of the ice during drilling and handling By the time the samples are analysed any contamination during drilling has already occurred. It is no longer a risk.
The brittle ice ceases eventually, does not look right. How does brittle ice cease? The word relax is used later in the section, and makes more sense, but how does it relax? is it a matter of gas diffusing out of bubbles through the solid ice until internal pressure balances with ambient? If so, an amusing parallel to
decompression sickness, one of my interests. If not, does the core expand to reduce internal gas pressure stress? What happens to deep cores with cubic structure? do they transform back to hexagonal? do the clathrate gases form bubbles again?
Yes, I think the parallel is definitely there, though I'm not clear on the internal crystal mechanics. For "cease", take a look at the diagram at the bottom of page 21,
here; it shows that the brittle ice zone is restricted to a certain range of depths, so from the point of view of the drillers, as time goes by, they encounter brittle ice after a way, and then after some more drilling it ceases, and the ice is no longer brittle. Can you suggest clearer wording? How about "As drilling continues to greater depths, the brittle ice zone eventually passed, and the core becomes stable again"?
Mike Christie (
talk -
contribs -
library) 16:03, 27 August 2017 (UTC)reply
The first paragraph of this section suggests that the bubbles are responsible for the brittleness, but I understand correctly, the brittle ice zone is where the clathrates are, and this zone actually has less bubble volume than the less brittle zones above and below it. • • •
Peter (Southwood)(talk): 10:25, 28 August 2017 (UTC)reply
Your comment prompted me to dig a little more, and I finally found a paper that unequivocally explains it. I added a few words to the brittle ice zone section; essentially they showed that the brittle ice zone ends when the clathrates begin. The brittle ice zone is the range of depths where the bubbles still exist, and pressure in the bubbles is great enough to crack the ice. Apparently clathrates are extremely stable, so even though Alley says somewhere that they will slowly break down, and bubbles will reappear, the process is too slow to make the ice brittle, while drilling at least.
Mike Christie (
talk -
contribs -
library) 10:03, 29 August 2017 (UTC)reply
Dating:
corrected for the presence of 14C produced directly in the ice by cosmic rays, - Is there anywhere to link to that explains how the 14C is produced?
I've linked 14C to
carbon-14, which talks about atmospheric production of 14C; the mechanism is the same. I could add a footnote if this isn't clear enough to the reader.
Mike Christie (
talk -
contribs -
library) 16:08, 27 August 2017 (UTC)reply
A link should be sufficient. The article is not about isotope formation, but it is something I wanted to look up at the time, so we have a sample of at least one for whom it will be useful. • • •
Peter (Southwood)(talk): 19:33, 27 August 2017 (UTC)reply
It's linked -- it's actually "Project", not "Program", though I have made this mistake myself at least once and there may still be an errant version in there somewhere. It's linked in the lead and again near the end.
Mike Christie (
talk -
contribs -
library) 16:11, 27 August 2017 (UTC)reply
Ref Langway 2008 only has 57 pages, (numbered to 47) in the linked pdf. Page ref in sources is to pages 101 to 117, which may be is correct for original publication, but is confusing. I don't know what the recommended work-around would be. Content claiming Langway (2008), pp. 27–28. as ref (116) is supported on spot check.
Bleah. That's a situation I've not run into before.
Ealdgyth, you're an expert on this sort of thing; what's a good way to handle that?
Mike Christie (
talk -
contribs -
library) 16:15, 27 August 2017 (UTC)reply
Maybe the source can be cited as originally published in journal XXX, pages n to m, accessed via YYY website. Not sure of the syntax. • • •
Peter (Southwood)(talk): 10:37, 28 August 2017 (UTC)reply
Langway, Chester C. (2008).
"The history of early polar ice cores"(PDF). Cold Regions Science and Technology. 52 (2): 101–117 – via US Army Engineering Corps: Cold Regions Research and Engineering Laboratory.?
After some more thought I decided
WP:SAYWHEREYOUGOTIT applies here, and I've reworked it to point directly to the CRREL report abstract, since that's what I'm actually citing.
Mike Christie (
talk -
contribs -
library) 10:15, 29 August 2017 (UTC)reply
Pbsouthwood: Barring a couple of queries above, and the source query to Ealdgyth, I think I've responded to everything now. Thanks for the review.
Mike Christie (
talk -
contribs -
library) 16:15, 27 August 2017 (UTC)reply
well-written: By my standards, yes. I leave details of spelling and grammar to others. Comprehensibility and use of appropriate terminology look good to me
comprehensive: I have not noticed any major deficits, but I am not an expert in the field.
well-researched: Those citations I have checked are good.
neutral: No sign of a problem.
stable: No recent conflicts.
appropriate structure: Simple and logical. Seems appropriate.
length: Not too short, not too long.
media: Relevant and appropriate. Copyright etc checked by someone else.
Refs 46, An extremely brief reversal of the geomagnetic field, climate variability and a super volcano and 47, Blunier et al. (2007), p. 325., check out on 1 pre-selected item.
I'm not sure if I will have time to review the entire article, but I would like to weigh in on Criterion 1(a). A high standard of writing is expected in FA articles, but I see a lot of the sort of problems that
Tony's article warns about. Examples:
The only
ice sheets are in Antarctica and Greenland, so the statement is inaccurate. How about: An ice core is a
core sample from a
glacier. Common coring sites include
Antarctica,
Greenland, and high mountains.
Changed to "An ice core is a core sample that is typically removed from an ice sheet or a high mountain glacier": I think it's better to keep the distinction between glacier and ice sheet, since the sources don't use the terms interchangeably. I dropped the reference to Antarctica and Greenland; it's not important enough to mention in the first sentence of the lead.
Mike Christie (
talk -
contribs -
library) 19:38, 2 September 2017 (UTC)reply
First paragraph, last sentence is a bit wordy. How about: Cores are drilled with hand
augers (for shallow holes) or powered drills; they can reach depths of over two miles and contain ice up to 800,000 years old.
Next paragraph: plenty of unnecessary words (generally, it should be obvious we're talking about ice): Both the physical properties of the ice itself and of material trapped in the iceit can be used to reconstruct information aboutthe climate over the age range of the core. The ratio of oxygen and hydrogen isotopes in the ice provides information about ancient temperatures; and the air trapped in tiny bubbles in the ice can be analyzed to determine the level of atmospheric gases such as carbon dioxide ... Since
heat flow in a large
ice sheet is very slow, the borehole temperature is another indicator of temperature in the past. and these sources of informationThese data can be combined to find thein the best fitting climate model that best fits all the available data.
I think the paragraph should be split at "Impurities": Impurities in ice cores may depend on location.; for example, cCoastal areas are more likely to include material of marine origin, such as sea salt
ions. Greenland ice cores contain layers of
wind-blown dust that correlate with cold, dry periods in the past, when cold deserts were scoured by wind.
Radioactive elements, either of natural origin or created by
nuclear testing, can be used to date the layers of ice in the cores. Some volcanic events whichthat were sufficiently powerful to have distributedsend material around the globe leaveleft a signature in the ice which can be detected many different cores, allowing synchronization of thethat can be used to synchronize their time scales between two different locations.
That's the first two (three?) paragraphs. My suggestions are just a start; with more time, I think they could be further improved. Glancing over the rest of the article, I see similar problems, particularly unnecessary repetition of information. I'll do more if I can find time, but I hope this helps. RockMagnetist(
talk) 17:40, 2 September 2017 (UTC)reply
Thanks for the review; this is very helpful -- it's hard to see the problems in one's own prose. I've made the edits you suggested, with a couple of minor differences. The main one is that I kept "combined to find the climate model that best fits all the available data" rather than changing it to "combined in the best fitting climate model", because I want to retain the sense that the data comes first and that model is constructed to fit the data. I'll go through the rest of the article for wordiness, and I'll see if I can find similar simplifications and improvements.
If you have time to do a more thorough review, both for content and prose, I'd really appreciate it -- I'm not a subject matter expert, and it would be good to get more input from someone with more expertise.
Mike Christie (
talk -
contribs -
library) 19:38, 2 September 2017 (UTC)reply
I think your take on the climate model is better. I started to edit the first section, but got into an edit conflict with you, so I'll wait for you to have a crack at it. RockMagnetist(
talk) 19:54, 2 September 2017 (UTC)reply
OK, I'm done for now -- I found more to fix at the start of the article, which I'd like to think is because the prose gets better, but may be just because I started to glaze over trying to critique my own prose. It's all yours.
Mike Christie (
talk -
contribs -
library) 20:36, 2 September 2017 (UTC)reply
Taking the helm now. One question, though - I notice you said "ice sheet or glacier", but according to the lead of
glacier, an ice sheet is just a form of glacier. I'd like to change "ice sheet" to "glacier" through most of the article. Any objections? RockMagnetist(
talk) 22:05, 2 September 2017 (UTC)reply
I think that would be confusing, but I'll do some looking through sources and report back. As far as I'm aware (with a layman's understanding of the sources I've read) the term "ice sheet" is only used for Greenland and the Antarctic; "glacier" seems to be used to refer specifically to a stream of ice. For example, the
Jakobshavn Glacier in Greenland is a moving stream of ice attached to the Greenland ice sheet. The distinction is not used much in this article, but it seems to be real. I'll see if I can find support for one position or the other.
Mike Christie (
talk -
contribs -
library) 22:12, 2 September 2017 (UTC)reply
Googling for "glossary glaciology" finds
this, which unambiguously states that glaciers and ice sheets are different. There's also
this, which doesn't define "ice sheet" but defines "glacier" in a way that would seem to exclude ice sheets.
Mike Christie (
talk -
contribs -
library) 22:19, 2 September 2017 (UTC)reply
Both of those could be read a different way, but I also found a book titled
Dynamics of ice sheets and glaciers. Maybe there isn't a consistent terminology. However, most of the material in this article can equally well apply to glaciers or ice sheets, so maybe we need to come up with a compact way of referring to both at once. RockMagnetist(
talk) 22:31, 2 September 2017 (UTC)reply
On a different subject, the citations are fine from a stylistic point of view, but would be easier to use if there were links to the sources using {{sfn}} or {{harvnb}}. That could easily be implemented using global search and replace. Or a more compact presentation could be achieved with {{rp}}. RockMagnetist(
talk) 22:39, 2 September 2017 (UTC)reply
I've never worked with either of those styles, and the few times I've edited an article with them I haven't found them intuitive to work with; probably a combination of laziness and inertia on my part. They also don't play well with
VE, which is my preferred editor. I've no objection to you or anyone else changing the citations to another style, but it's not something I would do myself.
Mike Christie (
talk -
contribs -
library) 11:29, 3 September 2017 (UTC)reply
In the section on coring, one thing is a little puzzling. You mention electromechanical drills in the first paragraph, and then there is no further mention until you are comparing them with thermal drills. I presume most of paragraphs 2-5 are referring to electromechanical drills - is that true? RockMagnetist(
talk) 23:16, 2 September 2017 (UTC)reply
Also, the concept of a string of drill pipe was a little unclear. At first I pictured something that was snaking around the core. RockMagnetist(
talk) 23:26, 2 September 2017 (UTC)reply
Not all the material in those paragraphs is relevant only to EM drills; cuttings aren't an issue for thermal drills, but drilling fluids are required for deep boreholes regardless of the drill type. You can have a cable-suspended thermal drill or use wireline technology on a thermal drill, in theory; I don't know of an example, which I think is because thermal drills are rarer. The best reference I have (Talalay 2016) is specifically about mechanical ice drilling -- I think the paucity of references on thermal ice drilling is because it is used less, particularly for deep cores. For
drill string I added a link; does that help?
Mike Christie (
talk -
contribs -
library) 11:29, 3 September 2017 (UTC)reply
Coordinator notes: Looking through, I see we have a source spot check, but I don't see a check for source formatting/reliability. If I haven't missed it, one can be requested at the usual place. Also,
RockMagnetist, do you have anything further to add?
Sarastro1 (
talk) 21:27, 13 September 2017 (UTC)reply
Support - a very well organized, well researched article. I am done with the copy edits, so I think the writing passes muster now. Nice job, Mike! RockMagnetist(
talk) 16:38, 20 September 2017 (UTC)reply
Source review
Source review - spotchecks not done
There are several harv errors in both References and Sources - suggest using
this script Done
RockMagnetist is converting the citations; they should be gone when he's done.
Mike Christie (
talk -
contribs -
library) 11:50, 14 September 2017 (UTC)reply
Be consistent in whether you use "et al" or spell out all authors Done
I use et al for more than two authors; there were several that were inconsistent with that but I think all are now fixed.
Mike Christie (
talk -
contribs -
library) 11:45, 14 September 2017 (UTC)reply
Actually there were several left, but I fixed them all. I could be wrong, but I had the impression that the preferred style was to list all the authors. Most of the time that is easy enough because of the citation forms that fill the fields in for you. RockMagnetist(
talk) 16:05, 14 September 2017 (UTC)reply
Generally your web refs are a bit off in terms of works vs publishers. Organizations are publishers, website names are works (but need consistent formatting in terms of whether www. is included)
@
Mike Christie: This is still off - AAAS, Emporia, Niels Bohr Institute etc are all publishers, not works.
Nikkimaria (
talk) 03:08, 15 September 2017 (UTC)reply
Nikki, I've fixed several of these by changing "website=" to "publisher=". It appears the "website=" parameter displays in italics so looks like the work, but if I have the publisher I don't think I need that in most cases. For EnvironmentalChemistry.com the name of the publisher appears to be the name of the website; I used the publisher parameter there too. Let me know if these now look OK.
Mike Christie (
talk -
contribs -
library) 11:59, 16 September 2017 (UTC)reply
ISBN for FN52? Done
I got the text from
a Google Books display which does not show the ISBN. Searching for copies of the book didn't bring up anything with the second edition's ISBN. Is there another way to find this?
Mike Christie (
talk -
contribs -
library) 11:45, 14 September 2017 (UTC)reply
Mike, if you scroll down to the bottom of the Google Scholar page, you can find the isbn. I also changed it to cite encyclopedia. RockMagnetist(
talk) 16:11, 14 September 2017 (UTC)reply
FN67 has duplicated website name Done
FN73 should include author and publication date Done
Why do some short cites use {{harvnb}} and others not? Done
Again this is because of the citation conversion; they should be gone soon.
Mike Christie (
talk -
contribs -
library) 11:50, 14 September 2017 (UTC)reply
FN118 date formatting doesn't match other citations Done
That was just related to the harvnb transition. RockMagnetist(
talk) 16:24, 14 September 2017 (UTC)reply
Can you double-check the ISBN for Talalay 2016? It throws up errors on Worldcat and GBooks
That's definitely what's on the book. It appears to be
this book, which has a completely different ISBN. The verso of my copy has text partly in Chinese, and it says it was published by "Geological Publishing House" in Beijing. Perhaps it's a pirated book and the ISBN is bogus? Not sure what do with the ISBN in this case.
Mike Christie (
talk -
contribs -
library) 11:50, 14 September 2017 (UTC)reply
this copy has preview on Google Books. Maybe you could switch to this after double-checking the citations. RockMagnetist(
talk) 16:36, 14 September 2017 (UTC)reply
Interesting. Given that there have apparently been changes within the text, not sure we can be certain a pirated version is an accurate representation of Talalay's work.
Nikkimaria (
talk) 14:34, 14 September 2017 (UTC)reply
Nikki, I checked the preview that RockMagnetist links to above, and the pages I can see match perfectly. I did some more Googling and I don't think it's definite that this is a pirated book, and even if it were it would be more trouble for them to edit the text than it's worth. I think this is probably OK.
Mike Christie (
talk -
contribs -
library) 22:06, 14 September 2017 (UTC)reply
Ueda and Talalay needs reformatting - this seems to be a report, not a journal article Done
The first external link redirects to another page that seems less directly relevant.
Nikkimaria (
talk) 01:56, 14 September 2017 (UTC)reply
Some of the above inconsistencies result from my starting to add harvnb but not completing the task. I'll try to get to it tomorrow. RockMagnetist(
talk) 04:19, 14 September 2017 (UTC)reply
File:EPICA delta D plot.svg: Source file needs to explain how it was created, since the source URL has no images. Section is pertinent.
Looks like this information is already present?
Nikkimaria (
talk) 16:12, 14 September 2017 (UTC)reply
I was wondering about the "GNU" thing, which implies that there is an additional copyright.
Jo-Jo Eumerus (
talk,
contributions) 16:16, 14 September 2017 (UTC)reply
The chart was generated using gnuplot, so I expect GNU would cover any copyright derived from that transformation.
Nikkimaria (
talk) 16:17, 14 September 2017 (UTC)reply
Yes, but there is no license statement there for such a case. Or maybe the listing of "GNU" under the "permission" header means something else.
Jo-Jo Eumerus (
talk,
contributions) 15:11, 15 September 2017 (UTC)reply
File:Upper Fremont glacier ice cl36.png: License seems fine. The image and caption do not seem to be supported by the text however, which only discusses 14 C in the context of nuclear testing.
Technically a test of a nuclear bomb is still a nuclear bomb, but I agree the caption is disconcerting. I've changed it to "nuclear testing".
Mike Christie (
talk -
contribs -
library) 01:45, 15 September 2017 (UTC)reply
The first URL (the second one seems to be broken) mentions that there is a high res TIF file.
Jo-Jo Eumerus (
talk,
contributions) 15:11, 15 September 2017 (UTC)reply
I just downloaded it; yes, it's higher res, but the image quality is not that great so I don't think it's worth messing with -- it's a TIFF so would have to be converted anyway. And I see in the file history that the first upload did an automatic conversion to png, so perhaps that's what happened.
Mike Christie (
talk -
contribs -
library) 22:17, 15 September 2017 (UTC)reply
File:Vostok Petit data.svg: See, I always wonder what the Commons description is sourced from. Source link seems broken for the origin file. Seems otherwise pertinent.
The source links that count are the FTP links -- those are working. Is something else broken?
Mike Christie (
talk -
contribs -
library) 01:45, 15 September 2017 (UTC)reply
File:Gripsaw.jpg: Use seems fine for me, I just wonder how we know that the photo is licensed under such a license.
Not sure about this, though I do know that the user who uploaded it was a professional climate scientist at one time, so may have known the author personally. I can drop this file if you want; it's not critical to the article.
Mike Christie (
talk -
contribs -
library) 01:45, 15 September 2017 (UTC)reply
The gif link works for me. Does the caption need to be changed? The change in colour in the ice with depth can be seen in the image; that's what the caption refers to.
Mike Christie (
talk -
contribs -
library) 01:45, 15 September 2017 (UTC)reply
The notes on the image mention firn, but it's not a controversial point -- snow pack like this is snow at the top, then firn below that, then ice -- that's sourced in the article. The caption doesn't specifically say that what can be seen is firn; the image just illustrates someone physically taking samples, and the caption provides a bit more general information. Do you see a problem with this?
Mike Christie (
talk -
contribs -
library) 22:20, 15 September 2017 (UTC)reply
File:Icecore 4.jpg: Use seems fine for me, source link appears to be broken however.
I found a version of it
here, which does at least establish that the license is likely to be correct, but I can't find a current copy of the entire image.
Mike Christie (
talk -
contribs -
library) 01:45, 15 September 2017 (UTC)reply
Some file sources ought to not be in bare URL form.
I fixed a couple of sources; can you point me at anything else that needs fixing?
Mike Christie (
talk -
contribs -
library) 01:45, 15 September 2017 (UTC)reply
Coordinator query: I think we are just about there, but I just want to check if
Nikki and
Jo-Jo Eumerus are happy with the sourcing and images side of things.
Sarastro1 (
talk) 21:14, 21 September 2017 (UTC)reply
Closing note: This
candidate has been promoted, but there may be a delay in bot processing of the close. Please see
WP:FAC/ar, and leave the {{featured article candidates}} template in place on the talk page until the
bot goes through.
Sarastro1 (
talk) 20:30, 22 September 2017 (UTC)reply
The above discussion is preserved as an archive. Please do not modify it. No further edits should be made to this page.
This article is about one of the key tools of palaeoclimatology. Ice cores contain an extraordinary amount of information about past environments. I am not an expert on this topic, but have done a fair amount of reading and I think the article covers the ground fairly thoroughly, and is ready for FAC.
Mike Christie (
talk -
contribs -
library) 16:26, 26 August 2017 (UTC)reply
Support on prose per my
standard disclaimer. Well done. As always, feel free to revert my copyediting.
These are my edits. - Dank (
push to talk) 23:14, 26 August 2017 (UTC)reply
Support Comments by Pbsouthwood
A fascinating read, and accessible to an ordinary engineer (can't speak for the general public). A little heavy going towards the end at a single sitting, but my eyes get tired after a while when nitpicking. I also spent a bit of time referring to linked material, and noticed a few places where extra links would be nice if available, otherwise some explanation would help. • • •
Peter (Southwood)(talk): 12:18, 27 August 2017 (UTC)reply
Yes, it's very commonly used. The website is at
eastgrip.org, for example, and you can see most of their pages introduce the acronym and then use it for the rest of the page.
Mike Christie (
talk -
contribs -
library) 11:13, 27 August 2017 (UTC)reply
does not become denser with additional pressure - Why, then, is there a crystal structure change at about 1500m?
I've cut this, since I can't find an unequivocal statement that it is the case; the pages I was using to source this discuss the thinning but never explicitly say that it doesn't get denser. I think it's probably
WP:OR to make the statement, and it's probably technically not true since there must, as you say, be at least a slight difference for there to be a crystal structure change. When brittle ice relaxes there is no significant visible change in its volume, so the density can't change by more than a tiny fraction; the point I was trying to make was that the major changes in density are with the transition from snow to firn to ice.
Mike Christie (
talk -
contribs -
library) 11:14, 27 August 2017 (UTC)reply
... slowly flow outwards, thinning as they do so How is the rate of flow distributed over depth? I assume there is some variation.
Yes; there's a simplified diagram in Alley that shows the fastest flow at the top; this is because the top layers do the most thinning so they must be flowing faster. The details are apparently quite complex, and Alley glosses over them; I think I have more details in another source but I felt this was too much detail for this article. Perhaps
ice sheet could cover it in more detail.
Mike Christie (
talk -
contribs -
library) 11:15, 27 August 2017 (UTC)reply
I have added a see also link to
Ice-sheet dynamics, which doesn't say much at present, but it is where the information should be. Done. • • •
Peter (Southwood)(talk): 15:25, 27 August 2017 (UTC)reply
An ice core is a vertical column through an ice sheet which provides a sample of each layer of ice, - It was a bit of a surprise to see this in the penultimate paragraph of this section. Basically this is the definition. I would have expected to see it at one of the first statements about ice cores, possibly even in its own section, possibly the first section. Is an ice core always vertical? Perhaps all the information about ice sheets should be grouped together, and a separate section or subsection on what a core is.
I see your point, but I'm not sure what the best thing to do about it would be. The reason for that section's structure is that an ice core, and the reasons for retrieving one, aren't comprehensible without knowing about ice sheets and how they are formed. The sentence explaining what an ice core is naturally come after the description of ice sheets, not before. I was hoping that the lead would serve to give the background necessary for this section to seem reasonable. Would it work to move this sentence, edited somewhat, up to start the section? And ice cores are not always perfectly vertical, though they are generally meant to be so; the current EastGRIP core deviated substantially from vertical over this summer and effort was spent to return it to vertical.
Mike Christie (
talk -
contribs -
library) 15:49, 27 August 2017 (UTC)reply
It works well for me. On rereading I think that the 3rd from last paragraph of this section (starting "Cores are often drilled...") would be better as the last paragraph, as this keeps all the physical information about the ice sheet together. If you don't think so, no problem. • • •
Peter (Southwood)(talk): 10:25, 28 August 2017 (UTC)reply
I have been trying to find out exactly which phase the cubic ice below 1500m represents. Do you have access to the relevant pages of Alley? The phase diagram in
Ice and associated descriptions is not helping me.
I've wondered about that too, but have not seen an answer in the refs so far. Alley has no more information than I put in the article, but he cites
this paper, which has further refs. Let me know if you think there should more about this in the article.
Mike Christie (
talk -
contribs -
library) 15:58, 27 August 2017 (UTC)reply
I read the article linked above. It makes no mention of cubic crystal ice, just type II air clathrates which occur in a depth zone around 1500m, where apparently they are relatively stable and presumably have a lower energy state than hexagonal ice (Ice Ih) with bubbles. The clathrate has a cubic structure and higher compression resistance than gas bubbles in ice at higher pressures, so the bubbles and hex ice reform at greater depths. The brittle zone is where the clathrates are, and when they decay after decompression. the ice may develop microscopic cracks. Apparently the clathrate structure is slow to form and decay. The article on
Nitrogen clathrate has some of this background.• • •
Peter (Southwood)(talk): 19:33, 27 August 2017 (UTC)reply
Perhaps mention in this section that the clathrate zone reverts to hex ice again at greater depths, then when one gets to the section on brittle ice it would be clearer. • • •
Peter (Southwood)(talk): 10:25, 28 August 2017 (UTC)reply
The paper linked above doesn't say that, as far as I can see; it talks about hexagonal inclusions. I got the impression that the structure of the ice below the brittle zone wasn't well understood, so I've avoided being specific. Did you have a particular part of that paper in mind as giving additional details?
Mike Christie (
talk -
contribs -
library) 09:38, 29 August 2017 (UTC)reply
Since I wrote this I've read Uchida et al. (1994), now cited in the article, which makes things clearer. I think the text I added to the brittle zone section may address this.
Mike Christie (
talk -
contribs -
library) 10:15, 29 August 2017 (UTC)reply
Coring:
What is a wireline? (a wikilink would do) Is it the same as a cable suspended drill?
How does a cable suspended drill power the cutting head? how does it lock to the ice to allow torque to be exerted at the cutting head? (a wikilink would do)
When samples are analyzed, an outer layer may be removed to reduce the risk of contamination of the ice during drilling and handling By the time the samples are analysed any contamination during drilling has already occurred. It is no longer a risk.
The brittle ice ceases eventually, does not look right. How does brittle ice cease? The word relax is used later in the section, and makes more sense, but how does it relax? is it a matter of gas diffusing out of bubbles through the solid ice until internal pressure balances with ambient? If so, an amusing parallel to
decompression sickness, one of my interests. If not, does the core expand to reduce internal gas pressure stress? What happens to deep cores with cubic structure? do they transform back to hexagonal? do the clathrate gases form bubbles again?
Yes, I think the parallel is definitely there, though I'm not clear on the internal crystal mechanics. For "cease", take a look at the diagram at the bottom of page 21,
here; it shows that the brittle ice zone is restricted to a certain range of depths, so from the point of view of the drillers, as time goes by, they encounter brittle ice after a way, and then after some more drilling it ceases, and the ice is no longer brittle. Can you suggest clearer wording? How about "As drilling continues to greater depths, the brittle ice zone eventually passed, and the core becomes stable again"?
Mike Christie (
talk -
contribs -
library) 16:03, 27 August 2017 (UTC)reply
The first paragraph of this section suggests that the bubbles are responsible for the brittleness, but I understand correctly, the brittle ice zone is where the clathrates are, and this zone actually has less bubble volume than the less brittle zones above and below it. • • •
Peter (Southwood)(talk): 10:25, 28 August 2017 (UTC)reply
Your comment prompted me to dig a little more, and I finally found a paper that unequivocally explains it. I added a few words to the brittle ice zone section; essentially they showed that the brittle ice zone ends when the clathrates begin. The brittle ice zone is the range of depths where the bubbles still exist, and pressure in the bubbles is great enough to crack the ice. Apparently clathrates are extremely stable, so even though Alley says somewhere that they will slowly break down, and bubbles will reappear, the process is too slow to make the ice brittle, while drilling at least.
Mike Christie (
talk -
contribs -
library) 10:03, 29 August 2017 (UTC)reply
Dating:
corrected for the presence of 14C produced directly in the ice by cosmic rays, - Is there anywhere to link to that explains how the 14C is produced?
I've linked 14C to
carbon-14, which talks about atmospheric production of 14C; the mechanism is the same. I could add a footnote if this isn't clear enough to the reader.
Mike Christie (
talk -
contribs -
library) 16:08, 27 August 2017 (UTC)reply
A link should be sufficient. The article is not about isotope formation, but it is something I wanted to look up at the time, so we have a sample of at least one for whom it will be useful. • • •
Peter (Southwood)(talk): 19:33, 27 August 2017 (UTC)reply
It's linked -- it's actually "Project", not "Program", though I have made this mistake myself at least once and there may still be an errant version in there somewhere. It's linked in the lead and again near the end.
Mike Christie (
talk -
contribs -
library) 16:11, 27 August 2017 (UTC)reply
Ref Langway 2008 only has 57 pages, (numbered to 47) in the linked pdf. Page ref in sources is to pages 101 to 117, which may be is correct for original publication, but is confusing. I don't know what the recommended work-around would be. Content claiming Langway (2008), pp. 27–28. as ref (116) is supported on spot check.
Bleah. That's a situation I've not run into before.
Ealdgyth, you're an expert on this sort of thing; what's a good way to handle that?
Mike Christie (
talk -
contribs -
library) 16:15, 27 August 2017 (UTC)reply
Maybe the source can be cited as originally published in journal XXX, pages n to m, accessed via YYY website. Not sure of the syntax. • • •
Peter (Southwood)(talk): 10:37, 28 August 2017 (UTC)reply
Langway, Chester C. (2008).
"The history of early polar ice cores"(PDF). Cold Regions Science and Technology. 52 (2): 101–117 – via US Army Engineering Corps: Cold Regions Research and Engineering Laboratory.?
After some more thought I decided
WP:SAYWHEREYOUGOTIT applies here, and I've reworked it to point directly to the CRREL report abstract, since that's what I'm actually citing.
Mike Christie (
talk -
contribs -
library) 10:15, 29 August 2017 (UTC)reply
Pbsouthwood: Barring a couple of queries above, and the source query to Ealdgyth, I think I've responded to everything now. Thanks for the review.
Mike Christie (
talk -
contribs -
library) 16:15, 27 August 2017 (UTC)reply
well-written: By my standards, yes. I leave details of spelling and grammar to others. Comprehensibility and use of appropriate terminology look good to me
comprehensive: I have not noticed any major deficits, but I am not an expert in the field.
well-researched: Those citations I have checked are good.
neutral: No sign of a problem.
stable: No recent conflicts.
appropriate structure: Simple and logical. Seems appropriate.
length: Not too short, not too long.
media: Relevant and appropriate. Copyright etc checked by someone else.
Refs 46, An extremely brief reversal of the geomagnetic field, climate variability and a super volcano and 47, Blunier et al. (2007), p. 325., check out on 1 pre-selected item.
I'm not sure if I will have time to review the entire article, but I would like to weigh in on Criterion 1(a). A high standard of writing is expected in FA articles, but I see a lot of the sort of problems that
Tony's article warns about. Examples:
The only
ice sheets are in Antarctica and Greenland, so the statement is inaccurate. How about: An ice core is a
core sample from a
glacier. Common coring sites include
Antarctica,
Greenland, and high mountains.
Changed to "An ice core is a core sample that is typically removed from an ice sheet or a high mountain glacier": I think it's better to keep the distinction between glacier and ice sheet, since the sources don't use the terms interchangeably. I dropped the reference to Antarctica and Greenland; it's not important enough to mention in the first sentence of the lead.
Mike Christie (
talk -
contribs -
library) 19:38, 2 September 2017 (UTC)reply
First paragraph, last sentence is a bit wordy. How about: Cores are drilled with hand
augers (for shallow holes) or powered drills; they can reach depths of over two miles and contain ice up to 800,000 years old.
Next paragraph: plenty of unnecessary words (generally, it should be obvious we're talking about ice): Both the physical properties of the ice itself and of material trapped in the iceit can be used to reconstruct information aboutthe climate over the age range of the core. The ratio of oxygen and hydrogen isotopes in the ice provides information about ancient temperatures; and the air trapped in tiny bubbles in the ice can be analyzed to determine the level of atmospheric gases such as carbon dioxide ... Since
heat flow in a large
ice sheet is very slow, the borehole temperature is another indicator of temperature in the past. and these sources of informationThese data can be combined to find thein the best fitting climate model that best fits all the available data.
I think the paragraph should be split at "Impurities": Impurities in ice cores may depend on location.; for example, cCoastal areas are more likely to include material of marine origin, such as sea salt
ions. Greenland ice cores contain layers of
wind-blown dust that correlate with cold, dry periods in the past, when cold deserts were scoured by wind.
Radioactive elements, either of natural origin or created by
nuclear testing, can be used to date the layers of ice in the cores. Some volcanic events whichthat were sufficiently powerful to have distributedsend material around the globe leaveleft a signature in the ice which can be detected many different cores, allowing synchronization of thethat can be used to synchronize their time scales between two different locations.
That's the first two (three?) paragraphs. My suggestions are just a start; with more time, I think they could be further improved. Glancing over the rest of the article, I see similar problems, particularly unnecessary repetition of information. I'll do more if I can find time, but I hope this helps. RockMagnetist(
talk) 17:40, 2 September 2017 (UTC)reply
Thanks for the review; this is very helpful -- it's hard to see the problems in one's own prose. I've made the edits you suggested, with a couple of minor differences. The main one is that I kept "combined to find the climate model that best fits all the available data" rather than changing it to "combined in the best fitting climate model", because I want to retain the sense that the data comes first and that model is constructed to fit the data. I'll go through the rest of the article for wordiness, and I'll see if I can find similar simplifications and improvements.
If you have time to do a more thorough review, both for content and prose, I'd really appreciate it -- I'm not a subject matter expert, and it would be good to get more input from someone with more expertise.
Mike Christie (
talk -
contribs -
library) 19:38, 2 September 2017 (UTC)reply
I think your take on the climate model is better. I started to edit the first section, but got into an edit conflict with you, so I'll wait for you to have a crack at it. RockMagnetist(
talk) 19:54, 2 September 2017 (UTC)reply
OK, I'm done for now -- I found more to fix at the start of the article, which I'd like to think is because the prose gets better, but may be just because I started to glaze over trying to critique my own prose. It's all yours.
Mike Christie (
talk -
contribs -
library) 20:36, 2 September 2017 (UTC)reply
Taking the helm now. One question, though - I notice you said "ice sheet or glacier", but according to the lead of
glacier, an ice sheet is just a form of glacier. I'd like to change "ice sheet" to "glacier" through most of the article. Any objections? RockMagnetist(
talk) 22:05, 2 September 2017 (UTC)reply
I think that would be confusing, but I'll do some looking through sources and report back. As far as I'm aware (with a layman's understanding of the sources I've read) the term "ice sheet" is only used for Greenland and the Antarctic; "glacier" seems to be used to refer specifically to a stream of ice. For example, the
Jakobshavn Glacier in Greenland is a moving stream of ice attached to the Greenland ice sheet. The distinction is not used much in this article, but it seems to be real. I'll see if I can find support for one position or the other.
Mike Christie (
talk -
contribs -
library) 22:12, 2 September 2017 (UTC)reply
Googling for "glossary glaciology" finds
this, which unambiguously states that glaciers and ice sheets are different. There's also
this, which doesn't define "ice sheet" but defines "glacier" in a way that would seem to exclude ice sheets.
Mike Christie (
talk -
contribs -
library) 22:19, 2 September 2017 (UTC)reply
Both of those could be read a different way, but I also found a book titled
Dynamics of ice sheets and glaciers. Maybe there isn't a consistent terminology. However, most of the material in this article can equally well apply to glaciers or ice sheets, so maybe we need to come up with a compact way of referring to both at once. RockMagnetist(
talk) 22:31, 2 September 2017 (UTC)reply
On a different subject, the citations are fine from a stylistic point of view, but would be easier to use if there were links to the sources using {{sfn}} or {{harvnb}}. That could easily be implemented using global search and replace. Or a more compact presentation could be achieved with {{rp}}. RockMagnetist(
talk) 22:39, 2 September 2017 (UTC)reply
I've never worked with either of those styles, and the few times I've edited an article with them I haven't found them intuitive to work with; probably a combination of laziness and inertia on my part. They also don't play well with
VE, which is my preferred editor. I've no objection to you or anyone else changing the citations to another style, but it's not something I would do myself.
Mike Christie (
talk -
contribs -
library) 11:29, 3 September 2017 (UTC)reply
In the section on coring, one thing is a little puzzling. You mention electromechanical drills in the first paragraph, and then there is no further mention until you are comparing them with thermal drills. I presume most of paragraphs 2-5 are referring to electromechanical drills - is that true? RockMagnetist(
talk) 23:16, 2 September 2017 (UTC)reply
Also, the concept of a string of drill pipe was a little unclear. At first I pictured something that was snaking around the core. RockMagnetist(
talk) 23:26, 2 September 2017 (UTC)reply
Not all the material in those paragraphs is relevant only to EM drills; cuttings aren't an issue for thermal drills, but drilling fluids are required for deep boreholes regardless of the drill type. You can have a cable-suspended thermal drill or use wireline technology on a thermal drill, in theory; I don't know of an example, which I think is because thermal drills are rarer. The best reference I have (Talalay 2016) is specifically about mechanical ice drilling -- I think the paucity of references on thermal ice drilling is because it is used less, particularly for deep cores. For
drill string I added a link; does that help?
Mike Christie (
talk -
contribs -
library) 11:29, 3 September 2017 (UTC)reply
Coordinator notes: Looking through, I see we have a source spot check, but I don't see a check for source formatting/reliability. If I haven't missed it, one can be requested at the usual place. Also,
RockMagnetist, do you have anything further to add?
Sarastro1 (
talk) 21:27, 13 September 2017 (UTC)reply
Support - a very well organized, well researched article. I am done with the copy edits, so I think the writing passes muster now. Nice job, Mike! RockMagnetist(
talk) 16:38, 20 September 2017 (UTC)reply
Source review
Source review - spotchecks not done
There are several harv errors in both References and Sources - suggest using
this script Done
RockMagnetist is converting the citations; they should be gone when he's done.
Mike Christie (
talk -
contribs -
library) 11:50, 14 September 2017 (UTC)reply
Be consistent in whether you use "et al" or spell out all authors Done
I use et al for more than two authors; there were several that were inconsistent with that but I think all are now fixed.
Mike Christie (
talk -
contribs -
library) 11:45, 14 September 2017 (UTC)reply
Actually there were several left, but I fixed them all. I could be wrong, but I had the impression that the preferred style was to list all the authors. Most of the time that is easy enough because of the citation forms that fill the fields in for you. RockMagnetist(
talk) 16:05, 14 September 2017 (UTC)reply
Generally your web refs are a bit off in terms of works vs publishers. Organizations are publishers, website names are works (but need consistent formatting in terms of whether www. is included)
@
Mike Christie: This is still off - AAAS, Emporia, Niels Bohr Institute etc are all publishers, not works.
Nikkimaria (
talk) 03:08, 15 September 2017 (UTC)reply
Nikki, I've fixed several of these by changing "website=" to "publisher=". It appears the "website=" parameter displays in italics so looks like the work, but if I have the publisher I don't think I need that in most cases. For EnvironmentalChemistry.com the name of the publisher appears to be the name of the website; I used the publisher parameter there too. Let me know if these now look OK.
Mike Christie (
talk -
contribs -
library) 11:59, 16 September 2017 (UTC)reply
ISBN for FN52? Done
I got the text from
a Google Books display which does not show the ISBN. Searching for copies of the book didn't bring up anything with the second edition's ISBN. Is there another way to find this?
Mike Christie (
talk -
contribs -
library) 11:45, 14 September 2017 (UTC)reply
Mike, if you scroll down to the bottom of the Google Scholar page, you can find the isbn. I also changed it to cite encyclopedia. RockMagnetist(
talk) 16:11, 14 September 2017 (UTC)reply
FN67 has duplicated website name Done
FN73 should include author and publication date Done
Why do some short cites use {{harvnb}} and others not? Done
Again this is because of the citation conversion; they should be gone soon.
Mike Christie (
talk -
contribs -
library) 11:50, 14 September 2017 (UTC)reply
FN118 date formatting doesn't match other citations Done
That was just related to the harvnb transition. RockMagnetist(
talk) 16:24, 14 September 2017 (UTC)reply
Can you double-check the ISBN for Talalay 2016? It throws up errors on Worldcat and GBooks
That's definitely what's on the book. It appears to be
this book, which has a completely different ISBN. The verso of my copy has text partly in Chinese, and it says it was published by "Geological Publishing House" in Beijing. Perhaps it's a pirated book and the ISBN is bogus? Not sure what do with the ISBN in this case.
Mike Christie (
talk -
contribs -
library) 11:50, 14 September 2017 (UTC)reply
this copy has preview on Google Books. Maybe you could switch to this after double-checking the citations. RockMagnetist(
talk) 16:36, 14 September 2017 (UTC)reply
Interesting. Given that there have apparently been changes within the text, not sure we can be certain a pirated version is an accurate representation of Talalay's work.
Nikkimaria (
talk) 14:34, 14 September 2017 (UTC)reply
Nikki, I checked the preview that RockMagnetist links to above, and the pages I can see match perfectly. I did some more Googling and I don't think it's definite that this is a pirated book, and even if it were it would be more trouble for them to edit the text than it's worth. I think this is probably OK.
Mike Christie (
talk -
contribs -
library) 22:06, 14 September 2017 (UTC)reply
Ueda and Talalay needs reformatting - this seems to be a report, not a journal article Done
The first external link redirects to another page that seems less directly relevant.
Nikkimaria (
talk) 01:56, 14 September 2017 (UTC)reply
Some of the above inconsistencies result from my starting to add harvnb but not completing the task. I'll try to get to it tomorrow. RockMagnetist(
talk) 04:19, 14 September 2017 (UTC)reply
File:EPICA delta D plot.svg: Source file needs to explain how it was created, since the source URL has no images. Section is pertinent.
Looks like this information is already present?
Nikkimaria (
talk) 16:12, 14 September 2017 (UTC)reply
I was wondering about the "GNU" thing, which implies that there is an additional copyright.
Jo-Jo Eumerus (
talk,
contributions) 16:16, 14 September 2017 (UTC)reply
The chart was generated using gnuplot, so I expect GNU would cover any copyright derived from that transformation.
Nikkimaria (
talk) 16:17, 14 September 2017 (UTC)reply
Yes, but there is no license statement there for such a case. Or maybe the listing of "GNU" under the "permission" header means something else.
Jo-Jo Eumerus (
talk,
contributions) 15:11, 15 September 2017 (UTC)reply
File:Upper Fremont glacier ice cl36.png: License seems fine. The image and caption do not seem to be supported by the text however, which only discusses 14 C in the context of nuclear testing.
Technically a test of a nuclear bomb is still a nuclear bomb, but I agree the caption is disconcerting. I've changed it to "nuclear testing".
Mike Christie (
talk -
contribs -
library) 01:45, 15 September 2017 (UTC)reply
The first URL (the second one seems to be broken) mentions that there is a high res TIF file.
Jo-Jo Eumerus (
talk,
contributions) 15:11, 15 September 2017 (UTC)reply
I just downloaded it; yes, it's higher res, but the image quality is not that great so I don't think it's worth messing with -- it's a TIFF so would have to be converted anyway. And I see in the file history that the first upload did an automatic conversion to png, so perhaps that's what happened.
Mike Christie (
talk -
contribs -
library) 22:17, 15 September 2017 (UTC)reply
File:Vostok Petit data.svg: See, I always wonder what the Commons description is sourced from. Source link seems broken for the origin file. Seems otherwise pertinent.
The source links that count are the FTP links -- those are working. Is something else broken?
Mike Christie (
talk -
contribs -
library) 01:45, 15 September 2017 (UTC)reply
File:Gripsaw.jpg: Use seems fine for me, I just wonder how we know that the photo is licensed under such a license.
Not sure about this, though I do know that the user who uploaded it was a professional climate scientist at one time, so may have known the author personally. I can drop this file if you want; it's not critical to the article.
Mike Christie (
talk -
contribs -
library) 01:45, 15 September 2017 (UTC)reply
The gif link works for me. Does the caption need to be changed? The change in colour in the ice with depth can be seen in the image; that's what the caption refers to.
Mike Christie (
talk -
contribs -
library) 01:45, 15 September 2017 (UTC)reply
The notes on the image mention firn, but it's not a controversial point -- snow pack like this is snow at the top, then firn below that, then ice -- that's sourced in the article. The caption doesn't specifically say that what can be seen is firn; the image just illustrates someone physically taking samples, and the caption provides a bit more general information. Do you see a problem with this?
Mike Christie (
talk -
contribs -
library) 22:20, 15 September 2017 (UTC)reply
File:Icecore 4.jpg: Use seems fine for me, source link appears to be broken however.
I found a version of it
here, which does at least establish that the license is likely to be correct, but I can't find a current copy of the entire image.
Mike Christie (
talk -
contribs -
library) 01:45, 15 September 2017 (UTC)reply
Some file sources ought to not be in bare URL form.
I fixed a couple of sources; can you point me at anything else that needs fixing?
Mike Christie (
talk -
contribs -
library) 01:45, 15 September 2017 (UTC)reply
Coordinator query: I think we are just about there, but I just want to check if
Nikki and
Jo-Jo Eumerus are happy with the sourcing and images side of things.
Sarastro1 (
talk) 21:14, 21 September 2017 (UTC)reply
Closing note: This
candidate has been promoted, but there may be a delay in bot processing of the close. Please see
WP:FAC/ar, and leave the {{featured article candidates}} template in place on the talk page until the
bot goes through.
Sarastro1 (
talk) 20:30, 22 September 2017 (UTC)reply
The above discussion is preserved as an archive. Please do not modify it. No further edits should be made to this page.