Talk:Last glacial period
From Wikipedia, the free encyclopedia
 |
This article is within the scope of the Glaciers WikiProject, a collaborative WikiProject related to glaciers and glaciology worldwide. It may include the Glacier infobox. If you would like to participate, you can choose to edit the article attached to this page (see Wikipedia:Contributing FAQ for more information). |
| B | This article has been rated as B-Class on the assessment scale. |
[edit] Move to 'Ice Age'?
Given the number of geographically-specific names (Wisconsinian and Vistula can be added to the list in the article), would it make sense to move the article to Ice Age or The Ice Age? 68.81.231.127 19:01, 21 Jan 2005 (UTC)
- The more general article at Ice age explains that the topic of this article, under its various local designations— none of them fully satisfactory overall— is merely the most recent glacial event. Some writers prefer to call it the Wisconsinian Glaciation, emphasizing, as the stages of geologic time like the Cretaceous "Maastrichtian" do, that "Wisconsin" is simply a place where the episode was recognized. The "Würmian Glaciation" is also a familiar term in English-language discourse, though not Wikipedian, apparently (red-linked). (Wetman 08:54, 28 September 2005 (UTC))
- Würm glaciation seems to be more common, and redirects to this article. (SEWilco 14:48, 28 September 2005 (UTC))
I am inclined to move this article to The last ice age in view of the various names for it in this article. Comments? Abtract 18:16, 21 October 2007 (UTC)
I'd agree with "Last Ice Age", because everyone's heard of that whereas very few would know what "Wisconsin glaciation" refers to. EamonnPKeane 17:01, 15 November 2007 (UTC)
[edit] "BC" or "BP"?
The present article is somewhat inconsistently expressed in years Before Christ. Years Before Present, with a "Present" permanently fixed at 1950, reflects the best normal practice, however. (Wetman 08:54, 28 September 2005 (UTC))
- Who says 1950 is the present? I assumed ybp meant 2000, or 2005, or 2006, and was worried what this article would look like in 10 or 20 years, then thought about the cleanup issues created by using such a contrived notation, but nevermind. Xaxafrad 01:33, 9 December 2006 (UTC)
- Read my lips: a "Present" permanently fixed at 1950, reflects the best normal practice. Any high school text will give you a first clue. --Wetman 05:39, 9 December 2006 (UTC)
[edit] Inconsistent timeline?
Um, how is it that the "general glacial advance began about 70,000 BC" but "The Tahoe reached its maximum extent perhaps about 70,000 years ago" [i.e., 68,000 BC] Did those early glaciers really gallop?
[edit] Conflict with other data?
I found this page while looking for more info on a passing comment by Richard Dawkins (The Ancestor's Tale, pg 405): “... guessing that our ancestors, but not the chimpanzees’, passed through a genetic bottleneck not very long ago. The population was reduced to a small number, came close to going extinct, but just pulled through. There is evidence of a fierce bottleneck - perhaps down to a population of 15,000 some 70,000 years ago, caused by a six-year ‘volcanic winter’ followed by a thousand-year ice age. Like the children of Noah in the myth, we are all descended from this small population, and that is why we are so genetically uniform. Similar evidence, of even greater genetic uniformity, suggests that cheetahs passed through an even narrower bottleneck more recently, around the end of the last Ice Age.” Dawkins does not provide footnotes or endnotes, so I can't provide his sources, but the apparent contradiction with Wiki's summary is striking.
-
- You'll be interested to read Toba eruption and Volcanic winter. The Toba eruption seems like quite a specific culprit for our Genetic bottleneck: Toba catastrophe theory gives the details. --Wetman 12:22, 26 November 2005 (UTC)
[edit] other places
There is nothing in this article on
(1) The quite different character of the North American Cordellian
Ice Sheeet.
(2) Patagonian Ice Sheet
(3) New Zealand Glaciers
(4) ... and other places that maybe matter less.
I'm not the one to attempt this summary. 134.121.64.253 02:11, 14 January 2006 (UTC)
[edit] Contradiction
The intro says, "The general glacial advance ... reached its maximum extent about 18,000 BCE." Later the article says "The Tioga was the least severe ... of the Wisconsinan group and reached its greatest advance 20,000 years ago". If the Tioga was the least severe one would expect the maximum for the whole period would have been in the Tahoe or Tenaya periods more than 30,000 years ago. Either some change or some explanation required.
Secondly, the first sentence says, "The Wisconsin ... and Würm glaciation ... are the most recent glaciations ...". If (as it seems to me) this is one glaciation with many names (and several periods), shouldn't it read, "... is the most recent glaciation ...". Otherwise, if it is many glaciations, shouldn't it read, "The Wisconsin ... and Würm glaciations ..."? Nurg 03:16, 5 November 2006 (UTC)
- Second point: no, they are different things. They are chronostratigraphic units and therefore can be different (but contemporary) regionally. There should in the ideal situation be separate articles about them. -- Woodwalker (talk) 19:50, 16 November 2007 (UTC)
[edit] Name of the article
I think the name of this article is a bit misleading. The last ice age is technically the Karoo Ice Age. Technically, again, we're still in an ice age, referred to as the Quaternary glaciation, host to the many familiar glacials and interglacials. I think it would be most prudent, so as not to confuse the readers, to rename the article to Last glacial or Last glacial period (prefer the latter). If you explain in the article that, colloquially, "ice age" is sometimes used to refer to the period ice advances, but "glacial" is a more correct term to use, then this will be less confusing for the reader. ~ UBeR (talk) 21:19, 16 December 2007 (UTC)
- Agreed William M. Connolley (talk) 22:11, 16 December 2007 (UTC)
I've done this now. ~ UBeR (talk) 04:31, 19 December 2007 (UTC)
- What was "the name of this article" and what did "done this" do? -- SEWilco (talk) 19:16, 29 January 2008 (UTC)
[edit] Wisconsin vs. Wisconsinan
Checked on with University of Wisconsin Geology Department Library classifications - Wisconsin and Wisconsinan are both correct usage, but the former simply points to a full entry under the latter, which indicates Wisconsinan is the preferred term. Edited accordingly.69.23.137.73 (talk) 18:36, 23 January 2008 (UTC)
- Some results of a web search:
- Searching USGS gives both names, though Wisconsin Glaciation seems to be a more common term. The background stuff seems to prefer it, like Glacial Limits, National Atlas and Glaciations, Ice Sheets, and Glacial Lakes.
- Google search "wisconsin Glaciation" yields ca. 23.600 hits, "wisconsinan glaciation" ca. 6.060.
- Wisconsinan Stage is an official term of USGS, see GEOLEX search results. Both terms are listed, but Wisconsinan is marked as the term used by the U.S. Geological Survey.
- If you follow the link to Wisconsin, it reads (emphasis by me):
- Geologic Unit: Wisconsin
- Usage:
- Wisconsin glaciation (WI)
- Wisconsin stage (WI)
- Occasionally used as drift or till, but originally intended as a time term, now Wisconsinan.
- The problem is, there's a difference in definition between the "glaciation" and the "stage", so the term "Wisconsinan Glaciation" (122,000 to 10,000 yrs) would be a glaciation in Wisconsinan Stage-time (Radiocarbon dates range from 28,000 yrs B.P. for top of Altonian (no date on base of Altonian, though probably is about 75,000 yrs) to between 5000-10,000 yrs B.P. Pleistocene age.)
[edit] An [sanitised] is working here.
The articles that should link here have been sabotaged and vandalized. The article about the Wisconsinian Glaciation, a North American geological/glacial event, has been destroyed. The persons responsible need be banned. In that some art has been used in this wanton act of vandalism, it will take some weeks for us mere scholars to repair it. I am so angry. --Ace Telephone (talk) 09:06, 27 January 2008 (UTC)
- Dear Ace, please watch your language and calm down. You won't start any reasonable discussion whith a phrasing like this. I'd recommend renaming this topic on the talk page fast (please see the talk page guidelines).
- I think you have a point at least in that the move of the special article Wisconsinian to Last glacial period has not really been discussed here, on Wikipedia talk:WikiProject Geology or on the mover's talk page. The pages linking to Wisconsinian glaciation mostly point to a special designation and not to this general term here.
- I doubt the neccessity to assemble all last glaciations under a general article only, because there are essential differences in the definition terms. The redirects are justified though in the cases of very short articles like the former Devensian article. --Jo (talk) 10:55, 27 January 2008 (UTC)
- The move was done by people that do not understand the difference between geochronology (last ice age) and chronostratigraphic stages (Wisconsinian, Devensian, Weichselian, etc). The last can be regional definitions. The current structure seems to regard them all as the same thing, but they aren't. Ace has a point. Woodwalker (talk) 22:35, 27 January 2008 (UTC)
- Yes, he has indeed. So there should be some reworking on this article, like shortening of the paragraphs and some general editing, and the special terms have to be re-established. jm2c,--Jo (talk) 01:23, 28 January 2008 (UTC)
- I think the problem can be fixed within this article. I don't think we need a bunch of separate articles. ~ UBeR (talk) 03:14, 28 January 2008 (UTC)
- Beg your pardon, but no, you can't fix it within this article. Example: there's a lot of links pointing to Wisconsinan Glaciation, dealing speficically with the NA stages, and if you follow the link to Wisconsinan Glaciation, you're lost on top of Last Ice Age. Examples:
- Geology of the Yosemite area#Glaciations
- Lassen Volcanic National Park
- and so on etc etc. Go to the redirect page and check via What links here. Read the articles.
- The way this article was moved perhaps did follow the WP procedure for moving articles technically (apart from the missing discussion, which should have taken place first), but it doesn't make sense concerning the content. Obviously nobody really checked the links to Wisconsinan Glaciation (or to the other local glaciations, I bet). It would have been a good idea to at least change these links, pointing to Last Ice Age#Wisconsinan_glaciation.2C_in_North_America.
- Nobody looking for this North American glaciation wants to wade through all of the other stages or look for the Wisconsinan chapter in the TOC. On the other hand, someone trying to get an overview of the subject doesn't want to have all this special content in the article.
- And there's no need to unify all of the subcategories of last glaciations in one article. First it's not a bunch of last glaciations, there are only a few of them; second, there are a lot of categories with hundreds of subcategories - if you think about it, collecting all birds in one article ... - and exactly this is one of the strong features of WP: you can find in-depth information about very, very esoteric subjects, bound by links, explained in a general page etc.
- And last: I don't think there's a way to prevent somebody to change the redirect and create a new Wisconsinan Glaciation, and I'm shure someone will. This move was a bad one, there'd better been some discussion first, and instead of the move a new article on Last glacial period, pointing to all of the different glaciations.--Jo (talk) 11:49, 28 January 2008 (UTC)
- Actually we already had different articles on regional stages of the same age on the Dutch wikipedia, the Germans are now starting to do the same. Both these projects are far smaller than this one. If I have time I will try to help. Woodwalker (talk) 13:00, 28 January 2008 (UTC)
- What is the best way to proceed? I think the Wisconsinian article has to be restored to its version in November prior to the move as well as all major stages (Würm etc.), and the Last glacial period article has to be edtited so that it only gives a short description of the different terms used and appropriate links to them. It should concentrate on a more global view, describing causes, wildlife, human development under glacial conditions etc. The Wisconsinian article, in contrast, should drop all this general text which probably led to its move to Last glacial period, citing every single penecontemporous glacial stage, and just describe the North American situation. jm2c, --Jo (talk) 13:40, 29 January 2008 (UTC)
- The way this article was moved perhaps did follow the WP procedure for moving articles technically (apart from the missing discussion, which should have taken place first) isn't exactly polite either. The mv was proposed on the talk page, a reasonable time was left, no-one objected and one person agreed. There was nothing at all improper about the mv, from a procedures point of view William M. Connolley (talk) 21:26, 29 January 2008 (UTC)
- Restoring WG to its pre-mv state makes no sense to me. Only about 25% of the article was actually about WG, the rest was about the same time but in other places. I think that last glacial period is a sensible unifying article. When the WG/Devensian/Stoatonian subsections become big enough to get moved out into their own articles, they should be. LGP unifies a whole bunch of disparate geological stuff in a way that makes sense of them all. Anyone reading about one of them is very likely to want to know about what was happening at the same time elsewhere William M. Connolley (talk) 21:37, 29 January 2008 (UTC)
- There's a paragraph about moving to Ice Age from 2005, and there are indeed two responses discussing the actual move under the term Last ice age, not discussing any Last glacial period. I did not see them until you mentioned them, perhaps my fault.
- I think the LGP-article is a good idea. I don't think you're right about the subsection not being big enough to merit its own article. That's not the point, see Woodwalker's contributions. There is a need for a short, exclusive paragraph on these terms, giving at least temporal and spatial definition, and a link to LGP.
- Restoring WG to its pre-mv state makes no sense, that's right. I proposed to drop all the general text and to only describe the North American situation, the Wisconsin glaciation proper (see above).
- Apart from these considerations those links pointing slightly wrong still remain.--Jo (talk) 10:31, 30 January 2008 (UTC)
- Whether the WG section is big enough to be its own article is a matter of taste. If you want to split it out, thats fine by me. One reason for that is that the old WG article talked of it entirely within the LGP; whereas Ace seems to think of the WG as several events over a longer period. Dangling links... can be fixed William M. Connolley (talk) 18:50, 30 January 2008 (UTC)
- There must be a misunderstanding. See the above talk in Wisconsin_vs._Wisconsinan. The WG began 122,000 BP (according to other sources 70,000 BP) and lasted to 10,000 BP. The Karoo Ice Age in the 300–400 Ma period was in southern Africa, South America, Australia and India. The Ordovician glaciation was in Africa and South America, and that's all for the last 500 Ma. So this cannot be the reason for an extra article. The issues involved have been mentioned above. --Jo (talk) 20:22, 30 January 2008 (UTC)
- You'll need to sort that out with Ace then: The term Wisconsinian glaciation is quite local to North America, for three phases over about 500 million years. Those who oppose the term must be termed ignorant; should the article continue with this name, it can only be deprecated.Ace Telephone (talk) 05:38, 30 January 2008 from below William M. Connolley (talk) 20:38, 30 January 2008 (UTC)
- Yeah, I read that, and didn't want to comment on it, perhaps the meaning was not the Wisconsin Glaciation, but WI geological history. He's right about the term, though, it's a midwestern USA term. BTW, there's a good section about them all in the Pleistocene, very NPOV, if somewhat short. And if you read the Ice age, you'll see that every single glacial stage of it has its own article (in two cases it's a redirect to the british term, I admit) under a local term except..., yes, LGP.--Jo (talk) 21:05, 30 January 2008 (UTC)
- You'll need to sort that out with Ace then: The term Wisconsinian glaciation is quite local to North America, for three phases over about 500 million years. Those who oppose the term must be termed ignorant; should the article continue with this name, it can only be deprecated.Ace Telephone (talk) 05:38, 30 January 2008 from below William M. Connolley (talk) 20:38, 30 January 2008 (UTC)
- There must be a misunderstanding. See the above talk in Wisconsin_vs._Wisconsinan. The WG began 122,000 BP (according to other sources 70,000 BP) and lasted to 10,000 BP. The Karoo Ice Age in the 300–400 Ma period was in southern Africa, South America, Australia and India. The Ordovician glaciation was in Africa and South America, and that's all for the last 500 Ma. So this cannot be the reason for an extra article. The issues involved have been mentioned above. --Jo (talk) 20:22, 30 January 2008 (UTC)
- Whether the WG section is big enough to be its own article is a matter of taste. If you want to split it out, thats fine by me. One reason for that is that the old WG article talked of it entirely within the LGP; whereas Ace seems to think of the WG as several events over a longer period. Dangling links... can be fixed William M. Connolley (talk) 18:50, 30 January 2008 (UTC)
- Beg your pardon, but no, you can't fix it within this article. Example: there's a lot of links pointing to Wisconsinan Glaciation, dealing speficically with the NA stages, and if you follow the link to Wisconsinan Glaciation, you're lost on top of Last Ice Age. Examples:
- I think the problem can be fixed within this article. I don't think we need a bunch of separate articles. ~ UBeR (talk) 03:14, 28 January 2008 (UTC)
[edit] Driftless Area
The Driftless Area can be characterized as the supreme artifact of the Wisconsinian Glaciation, the region that should have been glaciated (but left behind no drift). The Wikipedia move was moronic, idiotic. The Wisconsinian involves five hundred million years of geologic history in North America, all of which are usually present in the Driftless. Trust me: I live on a hill 1200 feet and 17 miles above the 660 feet of the local pool and dam, about 17 miles away; we don't live in mountains, but something ever more peculiar.
The Wisconsinian Glaciation was local to North America. Ace Telephone (talk) 03:28, 29 January 2008 (UTC)
Wisconsinian Glaciation is the historic term. Wikipedia does not invent new nomenclature, but some [sanitised] decided to do so.Ace Telephone (talk) 03:28, 29 January 2008 (UTC)
- What "Wikipedia move"? -- SEWilco (talk) 05:11, 29 January 2008 (UTC)
- Can you at least try to remain a bit civil. This is not an unsolvable problem. ~ UBeR (talk) 07:04, 29 January 2008 (UTC)
- @Ace: I did support your point (see above), and you treat me like an idiot on my talk page. I know what the Wisconsinian glaciation is, and I didn't move the Wisconsinian article. Please be more careful and calm down.--Jo (talk) 13:40, 29 January 2008 (UTC)
- three colons in. I have been an idiot, but the decision to eliminate pre-Illinoian-age or Wolstonian glaciation, along with the Wisconsinian glaciation is silly. Wikipedia seems to be putting together an ideology that any glacial event in Eurasia shall not be mentioned vis-a-vis North America -- and all usual learned nomenclature shall be discarded.
- @Ace: I did support your point (see above), and you treat me like an idiot on my talk page. I know what the Wisconsinian glaciation is, and I didn't move the Wisconsinian article. Please be more careful and calm down.--Jo (talk) 13:40, 29 January 2008 (UTC)
The term Wisconsinian glaciation is quite local to North America, for three phases over about 500 million years. Those who oppose the term must be termed ignorant; should the article continue with this name, it can only be deprecated.Ace Telephone (talk) 05:38, 30 January 2008 (UTC)
- You mean several articles were merged into this one? Whatever happened hasn't been described above, despite mention that there was some sort of announcement or discussion. -- SEWilco (talk) 05:52, 30 January 2008 (UTC)
- No, I don't mean that. But the statement, in the article, the Pleistocene epoch, which ended between 10,000 and 15,000 BP, while accurate, reduces the North American event to a minor event. The last ice age acted differently on different continents. Preserve the usual names. The Wisconsinian glaciation describes 500 million years of the history of North America; don't complicate the encyclopaedia with issues of nomenclature. Ace Telephone (talk) 09:55, 2 February 2008 (UTC)
- Ace, what do you mean by 500 million years of the history of North America? To my knowledge the WG is a Quaternary glaciation, restricted to the Pleistocene, just as the line you cited states.--Jo (talk) 11:05, 2 February 2008 (UTC)
At this point, I'm not certain any of us know what we're talking about. I'm defending my article Driftless Area which is a spectacularly long-term local North American last-glacial-era event which indeed extended over a half-million years of the last ice age (but of course, describing an area that remained free of continental glaciers). The Driftless Area probably qualifies as a Geologic province. Ace Telephone (talk) 07:41, 3 February 2008 (UTC)
[edit] Confusion over dates
According to this article, the glaciation started about 70,000 years BP, but the article on the preceding Eemian interglacial states that it ended about 114,000 BP. What happened in the intervening period? Dudleymiles (talk) 20:47, 4 February 2008 (UTC)
- Its something of a difference between the geological and ice-core perspective. The article doesn't actually say the ice age started then; only that general glacier advance started then. It may be thinking about particular regions, like N America William M. Connolley (talk) 21:28, 4 February 2008 (UTC)
-
- The glacial and interglacial stages have been named according to international commisions. So the names and the local developments are not neccessarily identical. Local developments and local terms were coined to match the local geological evidence, which is different in detail in Asia, America, Europe or Antarctica. 70,000 is the time of maximum glaciation in the Tahoe stade of Wisconsin glaciation (see Last_glacial_period#Wisconsin_Episode_glaciation.2C_in_North_America), c. 115,000 the end of the Eem Interglacial in the official nomenclature.
- So in northern US it just continued to grow colder after 114,000 (a continuous trend since temperature maximum in Eem interglacial), until accumulation of snow and ice was sufficient to trigger the first advance of the local ice sheet, the beginning of oscillating glacial advance - retreat cycles approx. 90,000 - 70,000 (see the diagram in Pleistocene#Glacial_features for CO2 oscillations in Antarctica, thought to reflect glacial stages).
- Your question addresses the recently disputed problem here: the local terms for glacial stages are different and have to be adressed properly, and the difference between official nomenclature and local developments and definitions have to be clarified.--Jo (talk) 12:02, 5 February 2008 (UTC)
- The question wasn't really about local terms, though. If 70,000 is the time of maximum glaciation in the Tahoe stade of Wisconsin glaciation is really right, then the article is wrong to say that advance started then William M. Connolley (talk) 21:39, 5 February 2008 (UTC)
[edit] Driftless Area redux
My local geologic history lacks 500,000 years of continental glaciation! I live in the Driftless Area! Yes, local history -- an exemption from glaciation that needs an explanation. I've tried to explain it. And the silly change in name remains silly. Karst topography is not found in drifted areas. Deep steep canyons are not found in drifted areas. --Ace Telephone (talk) 05:43, 8 February 2008 (UTC)
- Oh, don't feel left out. Take a vacation in the Black Hills or Arizona so you'll feel at home. -- SEWilco (talk) 05:51, 9 February 2008 (UTC)
- Been there, done that. I'm just a little intense about the defense of my article, and the facts thereof (so are you).--Ace Telephone (talk) 05:13, 22 February 2008 (UTC)
- Your article?
- Been there, done that. I'm just a little intense about the defense of my article, and the facts thereof (so are you).--Ace Telephone (talk) 05:13, 22 February 2008 (UTC)
- Not too far from here! ~ UBeR (talk) 03:52, 8 May 2008 (UTC)
[edit] Let's involve a little science, shall we?
To get us started in the right direction, I changed "At the height of glaciation the Bering land bridge permitted migration of mammals and humans to North America from Siberia." to "At the height of glaciation the Bering land bridge permitted migration of mammals such as humans to North America from Siberia." I'm sure some will be shocked to learn that humans are a type of mammal!
Maybe someone else can pick up where I left off and make this article into something to be proud of? —Preceding unsigned comment added by 207.138.32.33 (talk) 22:57, 8 May 2008 (UTC)
