|WikiProject Environment / Climate change||(Rated Start-class)|
|WikiProject Geology||(Rated Start-class, Low-importance)|
I've removed the addition of Nanocycles method. It's not a recognised or important part of the history of varve research, and not yet peer-reviewed / accepted science. I think we need to create a general article on sedimentary rhythmites. I've made some comments on the nanocycles talk page too. NickW 08:51, 25 May 2005 (UTC)
Good to have a photo for this article. I've edited the caption slightly. I've also removed the external links because they both link to only very basic descriptions of varves - neither as comprehensive as this article. We should find some more useful and complementary external links. NickW 18:34, 6 September 2005 (UTC)
Varve genesis and Re: the edit by 184.108.40.206.
It would be worthwhile adding content regarding varve genesis - but it's a big subject. Most of the simplified versions in popular literature (textbooks etc..) have become so simplified as to be inaccurate as generalisations. Hence my removal of the content added by 220.127.116.11. NickW 12:23, 15 December 2005 (UTC)
Good to see a section dealing with varve formation. However, I've made some fairly radical edits to make it more accurate for the time being. The variety of varves around the world is often overlooked, while the misnoma that they are limited to glaciolacustrine environments is endlessly regurgitated in textbooks etc.. It's great to see the Santa Barbara varves appearing here - perhaps we should provide details of other important sites too. NickW 20:36, 28 April 2007 (UTC)
The depth of this article does not go very deep. It does not provide any assumptions that pertain to varves, so unless you know them going into reading the article then you are not going to have this information. There is also no discussion about the strengths and weaknesses of using this technique as a climate proxy. Furthermore, this article as a whole is very weak because it only discusses the history of research up until 2012 and then talks about how varves form. While these two things are important to know if you are trying to learn more about varves, just having these two sections does not make a complete article. There is nothing about the data collected, what the data means, or how the data is gathered. There is a note that says that the listed references are unclear and there are insufficient in line citations. A quick search using almost any search engine will reveal peer reviewed articles that could be used here, as there really is not any in the references that are recent. I will link to two of them below. To improve this article, i would add more subheads just to give a more encompassing overview of valve research, and the references section needs expanded to make the article more reliable.
http://adsabs.harvard.edu/abs/2014EGUGA..1613381K http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.444.5878&rep=rep1&type=pdf#page=8 Ugoliniaw (talk) 21:41, 26 February 2017 (UTC)Ugoliniaw
Meaning of "varva"
Could we find a more precise meaning of the Swedish word "varva"? When it's used about layers, it means "putting several materials in layers (alternating between the materials)". One example is a "pancake-cake" where you "varva" pancakes, cream and chocolate. Would a short and good translation of "varva" then be "alternate layers"? --Md2perpe (talk) 21:49, 31 December 2012 (UTC) (non-native English speaker)
Seawater exclusion uses opaque language
While it's useful information to mention that the effect will no occur in salt water, the description of why that is so is nearly useless. I hope someone can rewrite this part in a more lay-accessible language to explain why flocculation prevents varves. Thanks! Unclepea (talk) 05:11, 4 July 2013 (UTC) Never mind. I came back and fixed it myself. Thanks! Unclepea (talk) 05:24, 4 July 2013 (UTC)
I have read the article and noticed that the Swedish version is only a stub although the Swedish use is major. I also notice some errors, varve can be deposited in salt water and in presence of oxygen. I also noted that the fixing of exact date (in Sweden) all the way back to local end of glaciation is not mentioned. The reason that they did not consider varve good for dating (In "History of varve research" at the end) was not that the dates was uncertain, BUT that the age of C14 deposition was uncertain! Reading the article referenced (Radiocarbon dating: revolutions in understanding) shows that it was not concerned about the exact date of deposition but age of C14 in the deposition. (Surprising is that there is no mentioning of the absolute dating of the end of last icing through varve counting, The retreat of ice in Scandinavia is now dated to exact BC year! (That dating happened about 1980, before that there was some uncertainity of a decade or so.) I need some references to consider changing the article so I will refrain until I have checked the documents in SGU library.Seniorsag (talk) 16:13, 10 August 2015 (UTC)
Varve as a climate proxy
This article only makes brief mention in the lead section of the role of varve as a climate proxy, but does not further elaborate on this in the body of the article. There are explanations of the formation of varve, how researchers discovered that each layer of sediment in glacial lakes represented one year, and how this then enables them to create chronologies using varve. However, there is no clear mention of how varve is analyzed to understand climate trends.There are no assumptions, nor are there pros and cons regarding the use of varve as a climate proxy, as there is not much information on the subject to begin with. The only mention of effectiveness of these sediment layers in scientific research is their uncertain reliability if they were to be used to generate chronologies over longer periods of time.
Most of the sources used are from the past 10 years, but there are a few that are a bit more dated. There are, however, more recent scholarly articles that are more focused on the use of varve as a climate proxy, as well as how this data is collected and analyzed for this purpose. Upon looking at the Wikipedia page for Proxy (climate), which does include a section on lake and ocean sediments, I found a web page cited as a reference that is helpful in explaining generally how different climate variables affect varve, and thus how studying these layers of sediments can illustrate climate trends over a period of time. I was able to find two fairly recent peer-reviewed articles that clearly display the use of varve as a climate proxy. The first looks at varve records in the Northwest Territories region around Mirror Lake in Canada, and how they relate to the overall climate and glacial history of the region. The article provides clear examples of data analysis, as well as advantages and limitations to the use of varve as a climate proxy while comparing it to the use of tree rings, another climate proxy. The second article, from 2016, is titled “Functional clustering of varved lake sediment to reconstruct past seasonal climate,” and could contribute similar type of evidence to this Wikipedia article.
Overall, the article could benefit from expanding on the claim made in the lead section that varve has been used to study past climate change, as there are many recent sources that support this claim. Additionally, if possible, it could be of use to include a figure or two that relates to the data analysis aspect in these types of articles, to give readers a more clear idea of how data from varves is used in the field of paleoclimatology. JocA1 (talk) 23:30, 22 February 2017 (UTC)
My evaluation and opinion
I think that this page is well written and explains the idea of this proxy well. I would like to see another image or two in addition to the one already on the page, just to show a variety of what it looks like. Another suggestion I have to make the page more well rounded and current is to talk about global warming and how it could disrupt the warming and cooling leading to different rock layers. I think that I found two sources that could help and or support the information found on this page. http://www.sciencedirect.com/science/article/pii/S0277379115001262 is one while http://journals.sagepub.com/doi/abs/10.1177/030913339301700101?journalCode=ppga is another.
- "IPCC Third Assessment Report - Climate Change 2001". www.grida.no. Retrieved 22 February 2017.
- Tomkins, Jessica D.; Lamoureux, Scott F.; Sauchyn, David J. (1 July 2008). "Reconstruction of climate and glacial history based on a comparison of varve and tree-ring records from Mirror Lake, Northwest Territories, Canada". Quaternary Science Reviews. 27 (13–14): 1426–1441. doi:10.1016/j.quascirev.2008.04.012.
- Arnqvist, Per; Bigler, Christian; Renberg, Ingemar; Sjöstedt de Luna, Sara (1 December 2016). "Functional clustering of varved lake sediment to reconstruct past seasonal climate". Environmental and Ecological Statistics. 23 (4): 513–529. doi:10.1007/s10651-016-0351-1. ISSN 1352-8505.