Talk:Geology of Dorset

GA review fail

Lack of citations. Needs a lot of improvements. Sushant gupta 11:10, 27 August 2007 (UTC)

And basic fact checking - eg Gault Clay is not Tertiary! More seriously it does not mention that half the county is part of the Hampshire Basin, which indicates a more general problem with such articles. Most counties are not remotely defined by geology. There should be articles about regions that make some sort of geological sense, and a brief geology section in the main county article linking to the relevant region(s). The map is a valuable piece of work (but see my comments about spellings on commons)! Pterre (talk) 23:44, 1 March 2008 (UTC)

I think it's fair enough to have an article on the geology of a county, as thet will be where many people will start to understand the regional geology. These inappropriately subdivided article can refer to an article on the broader structure. However also a norrowly focussed article can allow treatment of beds, formations and fossils which could be too much detail for a broader article. It should be possible to improve so that it qualifies for GA though. Graeme Bartlett (talk) 03:52, 2 March 2008 (UTC)

Hi Graeme, I'm not about to propose the article for deletion. My point is that we should probably avoid people writing an article about the geology of every single county just for the sake of it. I've probably picked on a bad example, as Dorset has a lot of geology, even though the county boundary has no geological significance (and more to the point has changed since I began studying geology). In most cases a summary section in the county article ought to be adequate, linked to relevant regional stuff. In particular we need to avoid large repeated chunks. Pterre (talk) 11:20, 3 March 2008 (UTC)

WikiProject Dorset reassessments

I've changed the Dorset WikiProject's assessment values of this article, from 'B'/'Mid' to 'C'/'High'. An article covering something as fundamental as the geology of the whole county really should be of high importance (for comparison, I notice the Somerset WikiProject places Geology of Somerset as of 'Top' importance in their assessments), and I don't think this article is of sufficient length nor quality to warrant a 'B' rating (in fact as it stands, I think this article's subject matter is more like the physical geography of Dorset rather than the geology - it needs quite a lot of work). PaleCloudedWhite (talk) 22:51, 9 January 2012 (UTC)

I agree. I've removed the erroneous reference to Gault as Eocene and corrected the spellings in the map (see above), but I'm reluctant to do much to the article for the reasons mentioned above (1 March 2008), since when little of substance has happened. As you say, this article is bettter described as the physical geography of Dorset, mentioning the geology only to the extent that it is relevant to this aspect. Pterre (talk) 11:25, 10 January 2012 (UTC)

Hello Pterre - nice to see someone's out there! I confess that I hadn't read your previous exchange with Graeme Bartlett, and having now done so, I'm now unsure as to the best route forward (having just decided to make Geology of Dorset a 'High' importance article). I can understand your point about county geology articles in general, although I also think that they could provide the general reader with a good entrance to the topics involved. People tend to identify themselves with areas which have human cultural significance, rather than geological significance. Hence many people will proudly state "I come from Dorset", but rather fewer would claim "I come from the Hampshire Basin". This might seem as if I'm being facetious, but there is a serious point, which is that I think people with no particular interest in geology might actually be prepared to read about it, if it refers to an area which they identify with. As a consequence, I would favour trying to expand the article, although obviously there may be quite a few "Main article: etc." posted throughout. Unfortunately my own knowledge is insufficient to edit the article with any confidence, although considering that "Dorset has a lot of geology" as you say, I wonder if it's worth trying to coax someone else from the Geology WikiProject to have a look at it? PaleCloudedWhite (talk) 21:29, 10 January 2012 (UTC)

I'm not sure I agree totally. The article does talk about the soils, minerals and bedrock of the county and in doing this it has to relate to the geography. I think 'geology of..' is an apt title but I wouldn't oppose a move to 'geography of..'. In fact that might be better and would allow greater expansion. For me the lack of inline citations is far and away the biggest problem with this article. I live in Dorset so I should be able to get something from the local library--Ykraps (talk) 22:39, 10 January 2012 (UTC)

PS I see you are qualified to talk about geology whereas I am not so I bow to your superior knowledge.

Geology and physical geography are different but connected. Geology looks more at the actual rocks: how they are formed, how old they are, how the different strata relate to each other in layers and folds etc., whereas physical geography (at least part of it) looks at landscapes, and the forces and processes which produce them. Therefore the geology of an area is an important component of its physical geography. I'm still thinking about what could be the best way to proceed. I am wondering if Pterre might actually be right in questioning these kinds of article, not because I think having an article called 'Geology of Dorset' is wrong in principle, but because in practice in the context of a wider encyclopedia, the text might be repeating what's written in other articles. I actually think that the geology of Dorset is really interesting, and there's potentially a lot that could be written, but consideration has to be paid to all the other geological articles, some of which already deal with formations that occur in Dorset (e.g. Oxford Clay, Corallian Limestone etc.) Maybe it would be a better idea to have 'Geology of Dorset' (I still think it's worth having it as an article) as a relatively brief overview of the formations within the county, with lots of links to other more detailed articles, and then creating a new article called 'Physical geography of Dorset' which could deal with the landforms/landscapes as they are uniquely found within the county. This latter article could actually be really large, and might be the one worthy of the 'High' importance rating, whereas if the 'Geology' article is kept relatively brief, perhaps that indeed should be a 'Mid' rating? (Or an alternative way to execute this would be to re-name this article as 'Physical geography of Dorset' and then expand it, and then create a new 'Geology of Dorset' article on the lines outlined above..) PaleCloudedWhite (talk) 00:52, 11 January 2012 (UTC)

Rather than keeping this and creating a 'Physical geography of Dorset' article, it might be better to rename this article 'Physical geography...' or simply 'Geography of Dorset' and expanding it, incorporating both the geology and geography and the relationship between the two. If this article becomes too large, then perhaps it could be split. I think this would be a quicker fix but I'm happy to work with you whatever is decided. Dorset is perhaps of more interest than some other counties because of the huge variety of rock within it.--Ykraps (talk) 23:44, 11 January 2012 (UTC)

I am amenable to renaming and expanding this article, although as someone who studied geography (albeit about 25 years ago...), I'm not comfortable with calling it just 'Geography of Dorset', as that would be potentially an enormous article and I think the intention here is really only to cover the physical geography aspects (see Human geography and Physical geography to understand where I'm coming from on this). I do understand however that for many people, "geography" probably just means physical geography, and "physical geography" is an unfamiliar term, so it is not a straightforward issue. Before proceeding, I think it would be good to have some input from other contributors on this matter. PaleCloudedWhite (talk) 00:36, 12 January 2012 (UTC)

If article is to remain (and I accept there may be reasons for that), we need to lose the stuff about arable agriculture, dairy farms, county flower competitions, varying habitats etc. This is clearly not geology. "What makes Dorset's coast particularly important to geologists though are the series of landforms which occur so close together, on the concordant and discordant coastlines." Really? Not the exposure of miles of fossiliferous cliffs then? More on the economic geology, on the structure (monoclinal folding? basins?) etc. Pterre (talk) 09:22, 12 January 2012 (UTC) For example I note that there is an article for Purbeck Monocline, but this feature does not even get a mention. Pterre (talk) 09:33, 12 January 2012 (UTC) I've dug out some references (Arkell's 1947 Memoir of the geology of the country around weymouth, Swanage, Corfe & Lulworth"; a 1982 ed of BGS,s regional geology 'The Hampshire Basin and adjoining areas'; MR House's 1969 "The Dorset Coast from Poole to the Chesil Beach"), but I have nothing very recent. Ideally it needs someone with access to current thinking on the structure. Pterre (talk) 09:42, 12 January 2012 (UTC)

We can have articles on both physical geography and geology. In this case there is so much overlap that you may as well keep expanding the geology aspects and have physical geography of Dorset point here as a redirect. Overlapping does not matter, but a complete duplicate should be avoided. If there are topics missing here then that is not so much a reason to complain or rename but to expand and improve. But on the topic of assessment, importance is importance for our readers, and top or high does seem to be overrated. Perhaps look at the view stats to see how popular it is compared to other Dorset articles. Graeme Bartlett (talk) 20:56, 12 January 2012 (UTC)

I have been reflecting on the question of how many articles to have (and what to call them), and in a bit of a turnaround from my earlier comment, I wonder now if having an article called simply Geography of Dorset (in addition to an amended and expanded Geology of Dorset) might actually be a good option. Before I thought such an article might be too broad, and hence I thought it best just to outline the physical geography of the county in an article titled Physical geography of Dorset. However much of such an article would be providing a summary overview of other articles (such as Isle of Portland, Dorset Downs, Chesil Beach etc.) and needn't be overly large. Also describing the physical geography can readily lead on to other aspects of the discipline, such as historical geography and human geography (including subjects such as patterns of settlement, agriculture and industry etc.). Furthermore I think having a general geographical overview article and calling it Geography of Dorset could be an option which the general reader could relate to. So I am tentatively proposing 2 articles: keep the existing Geology of Dorset, but expand the geological information within it whilst simultaneously taking out the strictly non-geological elements, and move them (if suitable) to sit within a new Geography of Dorset article (which would obviously have a great deal more information besides). Both articles would have many links to other main articles, and of course there would be overlap between the 2 of them. PaleCloudedWhite (talk) 22:00, 12 January 2012 (UTC)

This sounds good to me! I don't have much time at present but I'll try to contribute. Pterre (talk) 22:09, 12 January 2012 (UTC)

I agree. Thanks PaleCloudedWhite for alerting me to this discussion which raises a number of pertinent issues. I created an article Geology of Monmouthshire and took the approach of describing the geology of the county 'period by period' or indeed 'system by system' but had considered other ways of tackling the place. I'm doing something similar at the moment with the Geology of Wales which had contained all manner of non geological material added I guess by non-geologists, which is fine, but which took it away from the subject of the title. I do agree that 'geology of county x' is a good way in, if only because so many county geographies already exist and so it provides a neat tie-in, a sibling article for a recognised tract of country. cheers Geopersona (talk) 22:12, 12 January 2012 (UTC)

I too like PaleCloudedWhite's two proposed article titles. For Geology regional articles they can follow what the typical book on the topic covers. In addition to the above (geological history, surface geology) we can have geophysics, economic geology, geohazards, fossils, institutions, history of the study, law, and notable geologists from the area. Soils and landscape can get a small mention, but would be better in the geography article. Graeme Bartlett (talk) 10:13, 13 January 2012 (UTC)

It seems we have consensus, which is good - it's pleasing when this is achieved as a result of bouncing ideas off other's comments. I like Geopersona's description of the 2 articles as siblings - I think they could complement each other well. If no-one objects, I'll try to at least make a start on the basic structure of the Geography article within the next few days or so, and begin removing stuff from the Geology article as well - though if anyone wants to remove stuff themselves now, please feel free (I can always retrieve the old saved page if I want any of its contents for the Geography article). I think the expansion of the Geology article would really benefit from a contributor with more expertise than myself. I think Graeme Bartlett has described some interesting topics which could be included (though I'm not trying here to conscript Graeme into doing the job!) - I wouldn't have thought of topics such as institutions and notable geologists from the area. PaleCloudedWhite (talk) 22:01, 13 January 2012 (UTC)

Dates in section headings

I think it would help the reader if the years matched up to the period/epoch names in each section title. Some have changed since the article was put together, others predated the article being put together. Having the Pal(a)eogene start at 66 and the Quaternary at 2.6 million years ago for instance would cause less confusion. There is of course the issue of some formations and groups extending across such boundaries so I haven't immediately made the change in case there are extenuating circumstances. cheers Geopersona (talk) 12:24, 24 December 2022 (UTC)

@Geopersona: The date ranges were chosen because of the way the main source book was set out. I really don't know enough about the subject so if you think there's a clearer way of setting out the article, please feel free. Thanks for starting a discussion first though. --Ykraps (talk) 22:37, 24 December 2022 (UTC)

@Ykraps: - ah, yes, it's the kind of problem that will arise frequently in geology articles I guess as so many accepted dates have changed over the years as indeed have so many of the names of rock successions - often multiple times - so that what was generally agreed in say 1911, is quite different in 1964 or 1998 or 2022. Various references will therefore differ according to when they were published, an individual one perhaps still being entirely relevant except for some of those items and, were the author to write it now, they'd simply swap the old for the new. We would understand that an author like T R Owen who (in an imagined phrase) wrote . . . deposition continued until the end of the Devonian would have been referring at the time of his writing in 1973 to a date of 345Ma whereas that same phrase would now imply the date 359Ma. Conversely, had he simply asserted a date of 345Ma - knowing that his readers in the 1970s would take that as the end of the Devonian - without other contextual information we would now assign that to 14 million years into the Carboniferous; not his intention! Tricky. Geopersona (talk) 03:51, 25 December 2022 (UTC)

The main source, Ensom, was published in 1998. Is it just that the names of the periods (jurassic, cretaceous etc) no longer fit with the times frames (186 mya, 140 mya etc) ? Because that would be a fairly easy fix, I would have thought. --Ykraps (talk) 08:21, 26 December 2022 (UTC)

Hmm, without access to Ensom, it's difficult to say quite what the best way to address the mismatches would be. Rounding to the nearest million, period boundaries are fixed presently at; Devonian 419-359, Carboniferous 359-299, Permian 299-252, Triassic 252-201, Jurassic 201-145, Cretaceous 145-66, Palaeogene 66-23, Neogene 23-2.6, Quaternary 2.6-present. Rounding to the nearest 0.5ma, the divisions between the early/middle and middle/late Jurassic are now fixed at 174 and 163.5Ma. My own preference would be to remove the dates from the titles - perhaps putting them in the opening lines of each section and have them headed either with the name of the period/epoch/stage or else with the name of the geological formations/groups e.g. Wealden Beds in place of 140–125 Mya (early Cretaceous) but neither approach can be used entirely satisfactorily on its own. Geopersona (talk) 08:40, 27 December 2022 (UTC)

I was thinking remove the bracketted period names. Would that work, do you think? --Ykraps (talk) 09:35, 27 December 2022 (UTC)

That would remove the mismatch(es) in the short term though a longer term fix might well use section headings that more readily relate to aspects of the county's geology, e.g. named rock units or events. cheers Geopersona (talk) 18:53, 27 December 2022 (UTC)

I've removed the period names from the sub-headings but feel free to revert or change as you see fit. Best --Ykraps (talk) 07:04, 28 December 2022 (UTC)

That removes the mismatch between periods and absolute dates, which needed to be sorted out, but I think we can be pretty certain that the numbers were derived from the periods as there will be little direct radiometric dating applied to this sequence, due to the lack of igneous beds/intrusions. An alternative might be to label the subsections relative to the events that affected the area, although that will take some thought. I'll try to come up with some suggestions. Mikenorton (talk) 17:45, 30 December 2022 (UTC)

Any ideas you have would be welcome. --Ykraps (talk) 07:48, 31 December 2022 (UTC)

And I'm now the owner of a copy of Ensom's book so I'll see what might work, per that as a reference. cheers Geopersona (talk) 07:51, 31 December 2022 (UTC)

That will be useful. Thanks. --Ykraps (talk) 08:12, 31 December 2022 (UTC)

Proposed section and sub-section names

@Geopersona: @Ykraps: My suggestion is that we replace the existing sections/sub-sections with:

Devonian (mention the Variscan)

Triassic (maybe include Permian?)

Uppermost Triassic to Jurassic

Lower Lias

Middle Lias

Upper Lias

Inferior Oolite

Great Oolite (with the Cornbrash added from the next sub-section)

Ancholme Group (minus the Cornbrash)

Kimmeridge Clay

Portland Group

Uppermost Jurassic to Cretaceous

Purbeck Group

Wealden Group

Lower Greensand & Selborne groups

Chalk Group

Paleogene

Neogene

Quaternary

The "Uppermost Triassic to Jurassic" may seem a bit unwieldy but most of the Lower Lias is Jurassic and it looks a bit odd in the Triassic - the same goes for the Purbeck Group, which is mainly Cretaceous. The only bit that needs moving is the Cornbrash, but I don't think that's an issue - thoughts? Mikenorton (talk) 12:55, 31 December 2022 (UTC)

Thanks Mike - that looks like a good workable proposal to me. We can also make some further tweaks to the body text (dates etc) to make it all hang together nicely. Geopersona (talk) 14:52, 31 December 2022 (UTC)

It seems a reasonable solution. My knowledge of the subject is quite limited so I don't think I'm much use here but I wish you both luck and a happy New Year. --Ykraps (talk) 09:21, 1 January 2023 (UTC)

Well, I've had a go at that - see what you think. I still need to come up with a citation for the Triassic, but that shouldn't be difficult, hopefully. Mikenorton (talk) 17:03, 1 January 2023 (UTC)

Thanks for doing that, it looks good to me. Geopersona (talk) 18:04, 1 January 2023 (UTC)

Kimmeridge Clay dates

@Geopersona: I've been going through the various subsections trying to replace all the dates with stratigraphic ages. I've reached the Kimmeridge Clay but I am a bit mystified about the 140 to 145 Mya currently used in that section, which matches the lowermost Cretaceous Berriasian, whereas the BGS give Kimmeridgian as the age (understandably, although the British definition has changed with time). The overlying Portland Group is Tithonian, so I would have expected the date range to be about 157 to 152 Mya. What does Ensom say? Mikenorton (talk) 17:42, 5 January 2023 (UTC)

@Mikenorton:Ch10 Blooming algae and the anoxic ocean? (pp 43-46) opens with 'Time:145 - 140Ma, Formation: Kimmeridge Clay'. The preceding chapter, Dorset all at sea: turtle stones and roller sand (pp 39-42) opens with 'Time:160 - 145Ma, Formations: Cornbrash, Kellaways Beds, Oxford Clay and Corallian', and the following one, titled Titanic ammonites and 'osses 'eads (pp 47-50) opens with 'Time:140 - 137Ma, Formations: Portland Sand and Portland Stone'. I can't see that he introduces the reader to the names of stages in the book at all. Not sure if that helps. Geopersona (talk) 08:14, 6 January 2023 (UTC)

I've gone back and looked at older timescales that Ensom might have used e.g. Harland (1990) and can find no explanation - they appear to be just plain wrong, which is concerning. The Portland Group is all Tithonian, 152–145 on the current timescale. Enworth is just talking about rocks, not about absolute dating, I presume, so I suggest that we ignore those dates and concentrate on the stratigraphy. Mikenorton (talk) 17:38, 6 January 2023 (UTC)