Talk:Lower Greensand Group

Recent revert

Hemiauchenia I see that you have corrected some errors in dates in the version I amended, but the date range is still wrong. 125-113 million years ago is the Aptian and does not include any of the Albian. The current citation to Hopson et al is not valid as it gives no page number, so I cited the BGS page on the Lower Greensand Group. This does not list Woburn Sands among the component parts and gives the period as Aptian/Albian, not early Albian. As you have cited BGS for your revert, please provide a BGS reference for your statements. Note that I am not saying that you are wrong, just that valid references are needed for going beyond the BGS page which was my source. Dudley Miles (talk) 20:29, 8 January 2020 (UTC)

Dudley Miles How familiar are you with british Geology? Your age range erroneously suggests that the Lower Greensand Group runs for the entirety of the Albian, when this is occupied by the Gault and the Upper Greensand Formation. The BGS age ranges ae very rough estimates as they are database entries, so when it says Aptian to Albian, in means any part of the Aptian to any part of the Albian, not that it runs through the entire period, it completely lacks nuance. You can see from this diagram that MikeNorton did that the LG does not go significantly into the Albian, as this is occupied by the Selborne Group. Hemiauchenia (talk) 20:40, 8 January 2020 (UTC)

I am not an expert, but I am aware that the BGS age ranges are approximate. I made the edit because the article had two different age ranges, both wrong and neither well sourced. I replaced them with one well sourced approximation. The information on sourcing of Mike Norton's Wikimedia image is vague and it is not a reliable source according to Wikipedia rules. As I wrote above, my concern is to get dates based on reliable sources, and as you are obviously an expert you are best placed to supply dates with citations to reliable sources. Dudley Miles (talk) 22:32, 8 January 2020 (UTC)

Dudley Miles The link to MikeNorton's work was more as a demonstration of the timeline and the fact that the lower greensand could not occupy the entire Albian rather than a source. I have added a pdf link to the source and a page number of the given source, it clearly states the age range to be "Aptian to Early Albian" under "Lower Greensand" on page 15, none of these give specific answers as to the precise age of the boundary though, but considering that the Gault is also described as being Early Albian, the lower greensand occupies relatively little time in the Albian, and is of primarily Aptian age. Hemiauchenia (talk) 22:44, 8 January 2020 (UTC)

The Folkestone Formation is shown as late Aptian/early Albian, so the end date for the Lower Greensand Group should not be shown as 113 Ma. As the international chronostratigraphic chart shows the dates for the Aptian as approximate I suggest showing the date range as c.125 to c.110 Ma.

Also, you reverted my deletion of the unreferenced comments on Woburn and Faringdon Sands, which are just two of several local names. These should be deleted or expanded with reference to p. 14 of your source. Dudley Miles (talk) 09:34, 9 January 2020 (UTC)

Woburn and Faringdon Sands are considered by the by the BGS to be formal geological formations, and constituents of the Lower Greensand Group per their BGS lexicon entries, which are referenced in their respectie articles, I do agree that both articles should be expanded though. I also agree with the 125-110 dates, as the boundaries for the Aptian and Albian are uncertain. Hemiauchenia (talk) 13:23, 9 January 2020 (UTC)

The local names listed on p. 14 of the pdf are Woburn Sand Formation, Uffington Red Sands Formation, Faringdon Sponge Gravels Formation, Calne Sands Formation and Seend Ironstone Formation. If two are mentioned then I think all should be. Dudley Miles (talk) 16:37, 9 January 2020 (UTC)

I agree that the Calne Sands Formation and Seend Ironstone Formation should be included as they have formal Bgs entries. From research the Uffington Red Sands Formation and Faringdon Sponge Gravels are sub-units of the Faringdon Sand Formation, so they're already included. Hemiauchenia (talk) 16:46, 9 January 2020 (UTC)