Talk:North Downs
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[edit] Landscape
I think "Due to the porous nature of the underlying chalk, the North Downs is generally a treeless landscape" is purely conjecture and indeed factually incorrect. Many many species of tree like good drainage.
Much of the downland is indeed treeless but this is due to them having been cleared of trees in the distant past and the regrowth being suppressed by grazing as can be witnessed by the increase in scrubland when grazing reduced. Mixed deciduous forrest is the climax vegetation.
Living as I do at he bottom of Wrotham Hill I can assure you that trees will happily grow on the North Downs if left to their own devices. Indeed before the intervention of man the downs were almost entirely forrested.
I agree, most of Ranmore, Boxhill, Reigate Hill and the Greensand hills of Leith Hill, Holmbury Hill and Pitch Hill are covered in trees. Also, the North Downs in many places consists of two sub-parallel ridges a few miles apart. The northernmost hills being chalk overlaying clay, the southernmost being greensand. The latter set of hills also now has a long distance path called 'the Greensand Way'. I shall consider a re-write over the next few weeks.
[edit] The Ends of the North Downs
Okay, the White Cliffs of Dover are pretty definitive, but where's the Hampshire end generally considered to be? 82.36.26.229 17:23, 16 September 2005 (UTC)
[edit] Re-written Article
I have re-written the article to place information under relevant headings. I have removed the "Towns near the North Downs" section as it is difficult to define and would be better placed under a catagory. If anyone is unhappy with the changes then they are welcome to edit or revert to the previous article. Spagus
[edit] Chalk ridge only?
Are the greensand hills that form a parallel ridge to the south of the chalk downs not considered part of the North Downs? They were created as a result of the same geological process. St. Martha's hill, which is mentioned in the article as part of the downs, is part of this greensand ridge, along with Leith Hill, Holmbury Hill and Pitch Hill.Robruss24 14:30, 14 August 2007 (UTC)
- I'm not an authority on this but I thought the greensand ridge was part of the upper weald. --LiamE 15:11, 14 August 2007 (UTC)
- This is disputed. The greensand ridge is often referred to as part of the North Downs and Leith Hill is often quoted as the highest point on the Downs. Peter Brandons book on the North Downs also writes about the Greensand ridge. The Greensand ridge also are included in both the Kent Downs AONB and Surrey Hills AONB. Furthermore, the North Downs Way also traverses St Martha's Hill which is part of Greensand Ridge. However, the NDW does not pass along the higher sandstone hills (Blackdown, Leith Hill or Toys Hill). The greensand does not form such an apparent ridge in the southern half of the weald (in Sussex) as it does in the northern half and unless anyone can correct me I believe that the South Downs refers exclusively to the chalk uplands from Eastbourne to Winchester. For consistancy with the South Downs article it would perhaps be best that the North Downs should refer solely to the chalk and a seperate article should cover the Greensand Ridge. GkgAlf 09:58, 17 August 2007 (UTC)
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- Is it a geographical error though (as stated in the 'Leith Hill' article)? I don't know how far the fact is true that it is only chalk hills which determine the name North Downs. Can you cite evidence?
- Can the National Trust [1],the National Trails website [2], The Leisure Guide [3] be so wrong? I will say the Surrey Wildlife Trust does state:[4]
- "The highest point in south east England, Leith Hill sits upon the Greensand Ridge that runs parallel with the North Downs through Surrey".
- Then the "Surrey Hills" website [5] combines all the locations under the catch-all title "Surrey Hills", but then carries on:
- "there are numerous other locations along the North Downs and Greensand Hills that afford a view over the surrounding countryside"
- The point I am making is, has it been established that the North Downs consist of chalk hills and chalk hills only, or is it conceivable that other types of soil/geological formations may be part of the name "North Downs". Can you actually cite any sources that this is so? I am afraid you will have to now that so many different opinions seem to be abroad. Or is it just a matter of 'you pays your money and takes your choice'?
- Personally, I think you might be hard put to disprove that the two different types of hill are that far removed from one another in as far as types of formations are concerned.
- This was part of the talk page of the Leith Hill article, which I have now included in this talk page. Dieter Simon 00:25, 6 September 2007 (UTC)
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- Okay - The NT clearly seperates the ND and GSR. From their site... "The North Downs is a chalk ridge that runs from the Hampshire border, eastwards through Surrey and Kent to the White Cliffs of Dover." The Leith Hill site says nothing either way that I can see. The Leisure Guide must be discounted. It is a circular reference quoting wikipedia. The other two quotes you have posted clearly differentiate between the 2. Put simply, the North Downs are a single 100+mile chalk cuesta running from Dover through Kent and Surrey and on to the Hampshire border. In comparison the GSR is a small feature and is both physically and geologically seperate. The OED specifies "Chalk uplands of SE England" for Downland. If it aint chalk, it aint the downs. Any other confusions that I can see stem from trying to use walks and AONB's to try and define the downs, which is of course bound to fail as it is never their purpose to do anything of the kind. --LiamE 01:01, 6 September 2007 (UTC)
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- The point I am making, Liam, about the National Trust is, it includes Leith Hill in its North Down list, that's all I am saying. Ok, discount the Leisure Guide, I agree I should have noticed our own source there. However, are you now going to discount our own articles, such as Greensand:
- "Upper Greensand and Lower Greensand, these strata tend to occur just beneath the Chalk and can be separated by...", or Geography of Kent:
- "The (Wealden) dome was formed of an upper layer of chalk, above subsequent layers of upper greensand, upper clay, lower greensand..."?
- What I am saying, it isn't so much that Leith Hill happens to be on a ridge called Greensand Ridge but that greensand is in fact intimately connected and associated with chalk, every time there is a chalk upland involved you will find greensand being one of the layers either under or even above the chalk layers. None better than the gov. uk. website about the South Downs:
- [[6]], which when you scroll down to NI.2 tells you:
- "The Blackdown to Petworth Greensand Hills form a prominent ridge of hills with steep escarpments that enclose the Milland Basin. This ridge of hills includes Black Down which, at 280m, is the highest point in the South Downs."
- So, you see, the divide is really only in the mineralogical composition of chalk and greensand, but not in where the different layers of chalk and greensand may be found, and that they actually go together where they occur. I am sorry, that really includes Leith Hill as one of the North Down hills on a ridge called Greensand Ridge.
- As for the OED, an admirable source of English, they will also quote what umpteen other dictionaries state, namely: "Chalk uplands of SE England", and I agree with that. The Greensand Ridge, however, is an outcrop of greensand among the many geological layers of the North Downs. Dieter Simon 23:53, 6 September 2007 (UTC)
- The point is that the chalk that forms all of the north and south downs is a single entity. Yes it overlays greeensand but that is neither here nor there to my mind. If you try reversing the argument you may see the fallacy. Instead of trying to include Greensand Ridge hills in the North Downs, how about including say, Box hill and Detling Hill in the Greensand ridge? They are not made of Greensand so they cant be, in the same way that hills not made of chalk cannot be part of the North or South Downs. The single overriding feature of the downs is that they are chalk hills. --LiamE 18:27, 7 September 2007 (UTC)
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I am not trying to include anything at all. I am citing a source, such as the 'Southdowns gov uk' website which states that the Blackdown Greensand Hills are part of the South Downs, and that the Blackdown is the highest point in the South Downs, in other words is part of the South Downs. I am not claiming anything. I am doing, what all Wikipedians are supposed to be doing, cite sources. These are not my ideas, but are facts which have been established by official bodies. This is one of the principles we in Wikipedia have: do not do own research but cite established sources. Please read up on the various articles which point this out. Please read also the sources I have mentioned which you don't seem to have done. Dieter Simon 00:35, 8 September 2007 (UTC)
- You do yourself a diservice by suggesting that I havn't read the sources. I have. And they are directly contradictory. Some say the North Downs include several hills that simply are not on the North Downs and some differentiate. I would suggest that you take a step back and look at what you are doing. You have quoted 2 refs to support Leith Hill being on the North Downs, one is hardly an authority and the other DIRECTLY contradicts your claim. Utterly ridiculous. May I quote from your source "The North Downs is a chalk ridge..." --LiamE 00:53, 8 September 2007 (UTC)
- If nothing further is forthcoming I'll remove the contradiction from the article tomorrow. --LiamE 14:33, 17 September 2007 (UTC)
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- I must say to you at this stage that "Leith Hill" in this article is linked to Leith Hill in which it states that it is the highest point in the North Downs. I don't know how you are going to reconcile this fact with the fact that you are taking out your so-called "contradictions". But there we are. Dieter Simon 18:00, 18 September 2007 (UTC)
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- What do I mean by so called contradictions? How about 1 (not particulary strong) source saying that Leith Hill is is part of the North Downs and and one saying the North Downs is a chalk ridge. Surely you will concede that Leith Hill is not on the chalk ridge that is the North Downs? I can see you will not agree with me on this, but if I cannot make you understand that a sandstone hill is by definition not part of a chalk feature some compromise must be found. I'll have a go now. --LiamE 14:05, 19 September 2007 (UTC)
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- Yes, I agree, we should find a compromise, and for that reason I have added a complementary item, citing from the Greensand article, re narrow bands of greensand in chalk and clay. Dieter Simon 21:44, 19 September 2007 (UTC)
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- Just to clarify Greensand does not appear in the chalk or gualt clay - they are sperate entities laid down at diferent times. The greensand is the oldest, there is then a fairly thin layer of gault clay and then later the chalk was laid on top. Deformation that produced the now weathered away wealden dome anticline means that these strata reach the surface at an angle rather than laying horizontal hence layers that were on top of each other are now side by side. It should further be noted that there is no causal link between the greensand and chalk, it was simply that conditions to create chalk were preceded by the conditions to create greensand. Although at first glance the greensand/gault/chalk occuring 1000's of miles apart in Europe and America may suggest that there must be some link between the layers when one considers that these rocks were laid down before the existance of the Atlantic as we know it today one can easily see why the same formation appears so far apart, namely that a single formation has been pushed apart by the nacent spreading ocean. --LiamE 22:32, 19 September 2007 (UTC)
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Hello. The following extracts are from the Wealden District volume of the British Regional Geology series published by the National Environment Research Council's Institute of Geological Sciences (4th Ed. 1965). You should be able to borrow a copy from the local public library.
Page 39 "The Weald proper is surrounded by the chalk downs, the North Downs extending from Farnham to Dover and the South Downs extending from Petersfield to Eastbourne. The greater part of the chalk downland is occupied by Upper Chalk; Middle Chalk and Lower Chalk crop out chiefly in the scarped slopes of the North and South Downs, and at the bottom of some valleys."
P67 "...the Lower Greensand escarpment which reaches nearly 1000 ft OD in the Leith Hill district of Surrey includes the highest part of the Weald... The Chalk Downs encircle the Lower Greensand hills from which they are separated by a narrow belt of low-lying ground... In contrast to that of the Lower Greensand the chalk escarpment is remarkably constant in height throughout its length..."
P69 "The district includes the four well-known hills of Leith Hill, Holmbury Hill, Coneyhurst Hill and Winterfold Heath, and forms the highest part of the Lower Greensand outcrop of the Weald, the top of Leith Hill being 965 ft above sea level."
I think that these extracts show that the British Geological Survey consider that the Greensand Ridge is not part of the North Downs and that the North Downs are purely a Chalk formation.Mertbiol 16:52, 24 October 2007 (UTC)
- Thank God for a decent source. Thanks very much Mertbiol. --LiamE 17:17, 24 October 2007 (UTC)
Two further references. (They are both from specialist academic geology books, so it may be difficult to obtain copies.)
- Benninson GM and Wright AE (1969) The geological history of the British Isles Published by Edward Arnold (London)
"Chert is important in the western outcrops and so reinforces the lower Greensand that it forms a higher outcrop at Leith Hill than that of the chalk Downs nearby." page 321
- Dines HG and Edmunds FH (1933) The Geology of the country around Reigate and Dorking published by the Department of Science and Industry Research
"The chalk hills or North Downs form a bold and striking feature rising abruptly on the north side side of Holmsdale and continuing except where broken by gaps across the district." page 1
If you would like to challenge this then you need to provide a peer-reviewed publication which explicitly says that the name North Downs is also used for the Greensand Ridge. The chalk and greensand outcrops may well be closely associated, but that does not mean that the same name is used for both. Mertbiol 12:35, 29 October 2007 (UTC)
- I should also add that the National Trust groups its countryside properties together under the control of a Head Warden and Property Manager. Leith Hill is grouped with other Surrey properties under the control of the North Downs office at Headley Farm, Box Hill. i.e. The use of "North Downs" in this instance solely reflects the local organisation of the NT. Mertbiol 14:21, 29 October 2007 (UTC)
Hi, Mertbiol and LiamE, I wish to apologise about the discussion on my part and that your points were absolutely correct. I should like to cite the reply I received to my query from Dr Donald T Aldiss, of the British Geological Survey as per the next section. Dieter Simon 01:09, 8 November 2007 (UTC) I have replied to Dr Aldiss and mentioned the two articles involved, 'North Downs' and 'Leith Hill'. So, if you find anything in the articles that is missing in the light of what he has said, please complement them. Hope that this will be satisfactory to everyone concerned. I shall also add this to the article "Leith Hill". Dieter Simon 00:06, 7 November 2007 (UTC)
- Now if we could get the good doctor editing these articles we'd be laughing. Good work Dieter. Any chance of getting his comments on the greensand article too as that still needs a rewrite. --LiamE 00:20, 7 November 2007 (UTC)
[edit] Email of Dr Aldiss of the British Geological Survey
Dear Mr Simon
Thank you for your enquiry of 1 November 2007.
You wrote: Three queries have been thrown up in a couple of Wikipedia articles: 1. Is it true that both the North Downs as well as the South Downs are pure chalk hill ranges and nothing but chalk hills?
2.Is the Greensand Ridge, for example, a purely vertical and separate inclusion and has no horizontal layers of greensand either underlying or overlaying layers of chalk in the Downs?
3. Is Leith Hill which is on the Greensand Ridge therefore not classified as being part of the North Downs at all?
I would be grateful if you could clear this up and allow me to quote your reply whatever it may be.
Reply from Dr Aldiss
1 One should be aware of a distinction between the rock type (lithology) 'chalk' (no capital letter), which is a type of rather pure fine-grained limestone, and the lithostratigraphic unit, the 'Chalk Group' (always with a capital letter), which is a succession of rock strata of Upper Cretaceous age. The Chalk Group is composed mostly of chalk but includes other rock types such as flint and 'marl' (clay-rich chalk).
In general, downland topography is formed by the Chalk, including both the North Downs and the South Downs. The Chalk in these hills is in some places overlain by superficial deposits such as gravels or the clay-with-flints, but otherwise it is true that the North Downs and South Downs are formed of nothing but the Chalk.
2 The Greensand Ridge is separate from the Downs. Again, one has to be aware of the distinction between 'greensand' (typically glauconitic sand or sandstone; literally 'green sand') and 'the Greensand', a lithostratigraphic term which usually refers to the Lower Greensand Group (of Lower Cretaceous age). The Lower Greensand does contain some greensand, but also much silt, clay and limestone: most of it is neither green nor sand. It forms a distinct layer below the Gault Formation and the Upper Greensand Formation which directly underlie the Chalk Group. The 'Greensand Ridge' typically refers to one of a series of escarpments formed by the Lower Greensand. In Surrey, the Upper Greensand is thin and is not separately marked by rising ground, but elsewhere (in Sussex and Berkshire, for example) it too forms an escarpment.
These groups and formations each occur in separate layers. In Surrey these dip northwards, generally at an angle of 2 degrees or less but increasing to as much as 55 degrees in the Hogs Back area, west of Guildford.
No greensand occurs above the Chalk, except in the sense that there are some thin beds of green glauconitic sand in the Lambeth Group and other Palaeogene-age deposits of the London Basin.
If you need further information about the stratigraphic units named here, please refer to the BGS Lexicon of Named Rock Units: http://www.bgs.ac.uk/lexicon/lexicon_intro.html
3 Leith Hill forms part of the Greensand Ridge, not part of the North Downs as most people would use the term.
If you wish to quote this information, please acknowledge that its source is the British Geological Survey.
I would be interested to know which Wikipedia articles have thrown up these questions, please.
yours sincerely
Don Aldiss
D T Aldiss, PhD CGeol
District Geologist, London and the south-east
British Geological Survey
Keyworth
Nottingham
NG12 5GG
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[edit] Improving article
I am hoping to expand the North Downs article over the next few days/weeks to add more information and references etc. I think the article on the Mendip Hills is a good template to use. --GkgAlf (talk) 15:40, 6 December 2007 (UTC)
Good to hear it. The article can always do with it. However, source material should not be removed. Dieter Simon (talk) 01:05, 7 December 2007 (UTC)
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- Dan Tuson's excellent Kent Downs (Tempus, 2007) provides considerable valuable content that could be used to strengthen this article. I am working my way through this and adding relevant citations to articles I am familiar with (Wormshill and Frinsted for example). I shall continue to edit here where applicable. --John Gibbard (talk) 20:52, 4 February 2008 (UTC)
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