# Identify these concentric markings on mortar in an old wall **URL:** \ **Category:** Factual Questions\ **Created:** [June 9, 2023, 1:29pm UTC](https://boards.straightdope.com/t/identify-these-concentric-markings-on-mortar-in-an-old-wall/985242 "2023-06-09T13:29:10Z")\ **Posts on this page:** 20\ **Page:** 1
**Author:** ![Mangetout](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mangetout/32/19_2.png) [@Mangetout](https://boards.straightdope.com/u/Mangetout)\ **Post date:** [June 9, 2023, 1:29pm UTC](https://boards.straightdope.com/t/identify-these-concentric-markings-on-mortar-in-an-old-wall/985242/1 "2023-06-09T13:29:10Z")
Out and about on my travels, I happened to walk past an old building with walls made from limestone and flint. All over the surface of the mortar, I observed whorls of concentric ridges. Here are some photos: > **[public](https://onedrive.live.com/redir?resid=B021FB3140391EBE%21150032&authkey=%21ABq4FGMvrJQy9_w&ithint=folder)** > > Folder The wall is quite old. Probably at least a few hundred years. It looks as though the mortar has been repointed maybe a decade or three ago. The repointing is a mortar based on Portland cement. It’s quite likely that the mortar beneath it, bedding the stones together, will be traditional lime mortar. The markings don’t appear to be the work of human artistry (if for no other reason than creating them would have taken longer than the repointing). They’re on vertical surfaces, and the examples at the bottom of the wall are more pronounced than the ones nearer the top. There is an overhanging roof, but there’s no way that these represent spots where there has been consistent fall of individual water drops - I don’t think they can be ripple patterns from drops falling (some of them are on slightly undercut surfaces) They remind me a little of desert rose type minerals. Did these grow on the surface of the cement? Or are they raised because material has weathered away? Why rings like this? What are they? ---
**Author:** ![Gryphea](https://avatars.discourse-cdn.com/v4/letter/g/e19b73/32.png) [@Gryphea](https://boards.straightdope.com/u/Gryphea)\ **Post date:** [June 9, 2023, 2:00pm UTC](https://boards.straightdope.com/t/identify-these-concentric-markings-on-mortar-in-an-old-wall/985242/2 "2023-06-09T14:00:21Z")
They look like " Liesegang rings" or “Flos Tectorii” caused during the deterioration of lime mortar. you can read an abstract here [Flos Tectorii degradation of mortars: An example of synergistic action between soluble salts and biodeteriogens - ScienceDirect](https://www.sciencedirect.com/science/article/abs/pii/S1296207415000679) if you want a jumping-off point for more research See also [https://twitter.com/TeresaCeli\_](https://twitter.com/TeresaCeli_) for more photos ---
**Author:** ![OldGuy](https://avatars.discourse-cdn.com/v4/letter/o/3bc359/32.png) [@OldGuy](https://boards.straightdope.com/u/OldGuy)\ **Post date:** [June 9, 2023, 4:50pm UTC](https://boards.straightdope.com/t/identify-these-concentric-markings-on-mortar-in-an-old-wall/985242/3 "2023-06-09T16:50:56Z")
If I click on that link I get a message that reports to be from Microsoft. “Because you’re accessing sensitive info, you need to verify your password.” Needless to say I’m not doing so. I can’t imagine how that information is considered sensitive. ---
**Author:** ![TriPolar](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/tripolar/32/3008_2.png) [@TriPolar](https://boards.straightdope.com/u/TriPolar)\ **Post date:** [June 9, 2023, 4:54pm UTC](https://boards.straightdope.com/t/identify-these-concentric-markings-on-mortar-in-an-old-wall/985242/4 "2023-06-09T16:54:57Z")
Good call by @Gryphea. An image search on [flos tectorii](https://www.google.com/search?rlz=1C1RXQR_enUS984US984&sxsrf=APwXEdedLIY6qKaRHAOTFxwqoiKyklJeiw:1686329550446&q=flos+tectorii&tbm=isch&source=univ&fir=RngAIRjrkAzPvM%252CnHMEhAxHT_LaQM%252C_%253BFWW5hHb-_YUmmM%252CxcLCsz-G99_OKM%252C_%253B9UKn9uuLUQHpPM%252CnHMEhAxHT_LaQM%252C_%253B_hi0ATyLGWNu8M%252CgOw75i-X-VNszM%252C_%253BALP62SemBxPb3M%252CMlfUSSY7jFFNdM%252C_%253BvBTQbuwaRmPHAM%252CnHMEhAxHT_LaQM%252C_%253Bdb7_1yejSdrlEM%252CAXOcvTez3_V0iM%252C_%253BxE3-2JGpftfU6M%252CMp2kKA_RTt3WuM%252C_%253Bht4J_IsT6H7tTM%252CgOw75i-X-VNszM%252C_%253Bf9DxtOjogwjkhM%252Cdlx3kZr0kMYK_M%252C_&usg=AI4_-kSNwG7HayVGXqHuPV3U8oW95NodYw&sa=X&ved=2ahUKEwiHiNCO07b_AhVAkYkEHd0gD5IQjJkEegQIDRAC&biw=1280&bih=579&dpr=1.25) shows a number of examples similar to the OP’s. Pretty cool looking. ---
**Author:** ![Mangetout](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mangetout/32/19_2.png) [@Mangetout](https://boards.straightdope.com/u/Mangetout)\ **Post date:** [June 10, 2023, 6:25am UTC](https://boards.straightdope.com/t/identify-these-concentric-markings-on-mortar-in-an-old-wall/985242/5 "2023-06-10T06:25:54Z")
Your caution is admirable. It’s a shared photo on Microsoft OneDrive, which I tested as accessible in an incognito browser, so I think the thing you’re experiencing might be related to your own Microsoft account settings, or something like that ---
**Author:** ![Mangetout](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mangetout/32/19_2.png) [@Mangetout](https://boards.straightdope.com/u/Mangetout)\ **Post date:** [June 10, 2023, 7:35am UTC](https://boards.straightdope.com/t/identify-these-concentric-markings-on-mortar-in-an-old-wall/985242/6 "2023-06-10T07:35:29Z")
Thanks @Gryphea - very useful. I had so much trouble searching for anything about the phenomenon just by descriptive terms ---
**Author:** ![susan](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/susan/32/17537_2.png) [@susan](https://boards.straightdope.com/u/susan)\ **Post date:** [June 10, 2023, 10:29am UTC](https://boards.straightdope.com/t/identify-these-concentric-markings-on-mortar-in-an-old-wall/985242/7 "2023-06-10T10:29:59Z")
Apparently not accessible without a OneDrive account. ---
**Author:** ![puzzlegal](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/puzzlegal/32/3827_2.png) [@puzzlegal](https://boards.straightdope.com/u/puzzlegal)\ **Post date:** [June 10, 2023, 12:59pm UTC](https://boards.straightdope.com/t/identify-these-concentric-markings-on-mortar-in-an-old-wall/985242/8 "2023-06-10T12:59:20Z")
Huh, i could read it from my phone. ---
**Author:** ![Mangetout](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mangetout/32/19_2.png) [@Mangetout](https://boards.straightdope.com/u/Mangetout)\ **Post date:** [June 10, 2023, 8:18pm UTC](https://boards.straightdope.com/t/identify-these-concentric-markings-on-mortar-in-an-old-wall/985242/9 "2023-06-10T20:18:37Z")
I tested it in a private browser window, which does not have a OneDrive account. Not sure what problem you’re experiencing. ---
**Author:** ![susan](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/susan/32/17537_2.png) [@susan](https://boards.straightdope.com/u/susan)\ **Post date:** [June 10, 2023, 11:18pm UTC](https://boards.straightdope.com/t/identify-these-concentric-markings-on-mortar-in-an-old-wall/985242/10 "2023-06-10T23:18:58Z")
"Welcome to OneDrive. Access and share your documents and photos anywhere, on any device. SIGN UP SIGN IN" ---
**Author:** ![carrps](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/carrps/32/2957_2.png) [@carrps](https://boards.straightdope.com/u/carrps)\ **Post date:** [June 10, 2023, 11:52pm UTC](https://boards.straightdope.com/t/identify-these-concentric-markings-on-mortar-in-an-old-wall/985242/11 "2023-06-10T23:52:42Z")
Is there also flint in some pics? ---
**Author:** ![chela](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chela/32/21582_2.png) [@chela](https://boards.straightdope.com/u/chela)\ **Post date:** [June 11, 2023, 12:44am UTC](https://boards.straightdope.com/t/identify-these-concentric-markings-on-mortar-in-an-old-wall/985242/12 "2023-06-11T00:44:11Z")
Some context on the wall would be helpful. ---
**Author:** ![Mangetout](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mangetout/32/19_2.png) [@Mangetout](https://boards.straightdope.com/u/Mangetout)\ **Post date:** [June 11, 2023, 6:40am UTC](https://boards.straightdope.com/t/identify-these-concentric-markings-on-mortar-in-an-old-wall/985242/13 "2023-06-11T06:40:26Z")
Yes, the wall is constructed of dressed flint and limestone blocks ---
**Author:** ![Mangetout](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mangetout/32/19_2.png) [@Mangetout](https://boards.straightdope.com/u/Mangetout)\ **Post date:** [June 11, 2023, 6:44am UTC](https://boards.straightdope.com/t/identify-these-concentric-markings-on-mortar-in-an-old-wall/985242/14 "2023-06-11T06:44:59Z")
What happens if you open the link in a private tab? ---
**Author:** ![Mangetout](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mangetout/32/19_2.png) [@Mangetout](https://boards.straightdope.com/u/Mangetout)\ **Post date:** [June 11, 2023, 6:45am UTC](https://boards.straightdope.com/t/identify-these-concentric-markings-on-mortar-in-an-old-wall/985242/15 "2023-06-11T06:45:58Z")
What context do you want to know? ---
**Author:** ![susan](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/susan/32/17537_2.png) [@susan](https://boards.straightdope.com/u/susan)\ **Post date:** [June 11, 2023, 11:08am UTC](https://boards.straightdope.com/t/identify-these-concentric-markings-on-mortar-in-an-old-wall/985242/16 "2023-06-11T11:08:45Z")
Good strategy–I can see the photos in Incognito mode! ---
**Author:** ![chela](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chela/32/21582_2.png) [@chela](https://boards.straightdope.com/u/chela)\ **Post date:** [June 11, 2023, 1:09pm UTC](https://boards.straightdope.com/t/identify-these-concentric-markings-on-mortar-in-an-old-wall/985242/17 "2023-06-11T13:09:58Z")
Thx. Where in the world is this wall? is it a ruin or still occupied? Inland or near the sea? ---
**Author:** ![Mangetout](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mangetout/32/19_2.png) [@Mangetout](https://boards.straightdope.com/u/Mangetout)\ **Post date:** [June 11, 2023, 6:11pm UTC](https://boards.straightdope.com/t/identify-these-concentric-markings-on-mortar-in-an-old-wall/985242/18 "2023-06-11T18:11:33Z")
It’s a stone outbuilding - possibly a former stable or small barn - in central Dorset, UK the sea is about 10 miles away as the crow flies; far enough for it not to feel ‘coastal’ at all - the building itself it’s made from local stone - limestone probably from quarries further north in the county; flints probably dug out of the ground on site or in the immediate locality. That’s all I know - I don’t know the history of it or anything like that - it’s just a place I happened to walk past. It has an intact roof so it appears to be at least sound and weatherproof, if not in full active use. ---
**Author:** ![Isilder](https://avatars.discourse-cdn.com/v4/letter/i/cc9497/32.png) [@Isilder](https://boards.straightdope.com/u/Isilder)\ **Post date:** [June 13, 2023, 11:32am UTC](https://boards.straightdope.com/t/identify-these-concentric-markings-on-mortar-in-an-old-wall/985242/19 "2023-06-13T11:32:56Z")
Ok, so the lime in the mortar provides a soluble material that will shift… the lime migrates. So the different amount of lime in the mortar results… the resistance to erosion has changed based on the amount of lime in it, which is based on the distance from the edges. So the curves ,shells, of different erosion resistance… and so the erosion happens differently. The same sort of thing that makes a spherical solid lump inside sedimentary materials… but often its iron forming the concretion… The evidence for it being related to the distance from the exposed surface… eg a sphere around a lump of iron, or a sphere forming around a lump of iron free materials. You get plane and grid concretions due to cracks which have formed a plane or network of planes … See [https://ozgeotours.yolasite.com/resources/Concretions.pdf](https://ozgeotours.yolasite.com/resources/Concretions.pdf) ---
**Author:** ![eburacum45](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/eburacum45/32/8690_2.png) [@eburacum45](https://boards.straightdope.com/u/eburacum45)\ **Post date:** [June 13, 2023, 11:39am UTC](https://boards.straightdope.com/t/identify-these-concentric-markings-on-mortar-in-an-old-wall/985242/20 "2023-06-13T11:39:42Z")
> [@Gryphea](#): > > They look like " Liesegang rings" or “Flos Tectorii” caused during the deterioration of lime mortar. > you can read an abstract here [Flos Tectorii degradation of mortars: An example of synergistic action between soluble salts and biodeteriogens - ScienceDirect](https://www.sciencedirect.com/science/article/abs/pii/S1296207415000679) > if you want a jumping-off point for more research > See also [https://twitter.com/TeresaCeli\_](https://twitter.com/TeresaCeli_) > for more photos Absolutely fascinating. I’ve occasionally seen effects like this, due to rising damp on the outside of buildings, but I had no idea that there were bacteria involved. I note that “Flos Tectorii” is a biological process while “Liesegang rings” appear to be a non-biological, geological process that happens in native rock.