Hertfordshire Puddingstone

[LucasBMylks]

I found this last year on one of my hunts. Looks just like a bit of hardcore (concrete) but it is actually a conglomerate called Hertfordshire Puddingstone. Pudding as in plum pudding, an English dessert.
I live in the county next to Hertfordshire.
I am not sure if it is an artifact but it ticks the boxes on its ergonomics.

[clovisoid]

Artifact or not, it's a very cool specimen.

[Hal Gorges]

Nice, never saw anything like that before...just looked em up, saw they were found up around the Great Lakes, if I lived in that neck of the woods I’d be lookin for some, thanks for sharing.

[LucasBMylks]

I didnt know that. Thanks Hal. Some more reading for me to do now.

[Olden]

Interesting material: harder than a concrete, and sometimes used in buildings

https://www.hertsmemories.org.uk/content/herts-history/topics/traditional-hertfordshire-project-2017/hertfordshire-archives-local-studies/hertfordshire-puddingstone

https://en.wikipedia.org/wiki/Hertfordshire_puddingstone

[LucasBMylks]

The `Church` took to using them too. Only as people believed in the mysteries of the stone `PRIOR` to the `Church` even existing.

[sailorjoe]

A very unusual specimen for sure. I never saw a chunk of conglomerate that looked like it was sawed to create a right angle and as you say the overall ergonomics seem to fit the idea of it being a tool. Very strange, indeed.

[LucasBMylks]

Yeah really weird....it fractures thru the pebbles and `the bit that sticks it together` like it is one whole lithic. Strange thing is, just like flint, we still dont know exactly how it is formed.

[sailorjoe]

Hi Lucas. I am not a geologist at al, having only one class in introductory geology in my college days many, many years ago, but HST if I did not misunderstand your comment to my post then yes we know how flint/chert was formed and also conglomerate. That is why I think your possible artifact is most unusual.

[Cecilia]

It’s beautiful! We have lotsa conglomerate here near the Savannah River, Georgia, but mostly the coloring is drab (I still keep it, though). The only British-type pudding we have is at the grocery store:
Quarantine has made me silly. But did eat sponge pudding a lot when lived mother country one summer many yrs ago. Went to St. Alban to look for Verulamium and Bleak House. Enjoy your phenomenal surrounding heritage, comforting plum pudding, and beautiful rocks! And, thank you for posting and reviving my memories.

[LucasBMylks]

Thank You Cecilia. You went to St. Albans? That is where this stuff is found in abundance!!

https://www.megalithic.co.uk/article.php?sid=10785

There is a bit less there now https://www.bbc.co.uk/news/uk-englan...herts-36203933

But I would`ve been sorely tempted myself if I saw that too.


As I understand it what you guys over there call pudding we here call custard.

[CMD]

That is some very nice conglomerate. One of our nearby parks has large outcrop ledges of conglomerate. It’s Upper Carboniferous in age, Rhode Island Formation. The larger the pebbles in pudding stone, the stronger the river that deposited them at its mouth in that distant past world....

[LucasBMylks]

Amazing! Thanks Charlie you have just answered the question I havn`t asked yet. After Hal mentioned the Great Lakes I went looking on-line and remembered I had looked at them before and noticed the pebbles were a lot smaller. This made me wonder and you have solved it for me. Top Man!

[CMD]

The outcrop in my photos overlooks Narragansett Bay, in the state of Rhode Island.

[painshill]

Hi Lucas. How've ya been?

Cool specimen.

Geologically, Hertfordshire puddingstone is what we call a ‘silcrete’… a rock which contains high purity silica (around 97% in this case) but, despite being composed of two phases, behaves as if it were a single rock. It has no pores, is frost-resistant, doesn’t readily weather and is virtually indestructible. Generally, there’s not much of it left in situ where it originally formed (in what is now the Chilterns), but it has been distributed further south as a result of glacial disturbance and transport.

In the early Palaeocene through to the beginning of the Eocene between 66-56 million years ago, there was rapid erosion of uplifted chalk deposits, releasing huge numbers of flint cobbles and pebbles into what was the beginnings of the North Sea. These stones were smoothed and rounded by wave action, geologically sorted to a typical size range of 10-20mm and deposited as shingle beaches or off-shore shoals mixed with silica sand.

Over the next few hundred thousand years these shingle deposits became subsurface land deposits as a result of falling sea levels and a brief period of ‘drying out’ during the Palaeocene-Eocene Thermal Maximum. Then, groundwater rich in silica from the surrounding rocks percolated through the shingle, precipitating to form a conglomerate of pebbles and sand, strongly bonded by a silica matrix. The groundwater was also iron-rich, resulting in generally brownish colourations (occasionally pinkish) from iron oxide staining.

Here’s a slice from my collection. You can cut and work this stuff without any danger of pebbles separating from matrix.



Local folklore holds that it has magical properties and, traditionally, a piece of it was given to newly-weds… probably as a fertility symbol. It was also said to protect against witchcraft, and there is a record from 1662 of a suspected witch being buried with a piece of puddingstone on top of her coffin (to keep her in). Among many colloquial names it’s also known as ‘growstone’, from a belief that it could multiply itself in an amoeboid fashion.

[LucasBMylks]

Hello Roger
I`m good yes thanks for asking.
Hope you and the Good Lady are doing well.

Wonderful input as always. I had read about the `drying out` sequence and it kinda fascinates me. Such a hard stone.

`to keep her in` had me crying.
The Mother-in-Law said she would claw her way to the surface and haunt me when she goes. So I was going to bury her face down! But maybe now i`ll just chuck this on top of her coffin.