Episode 84. London Geology

Join Hazel Baker as she talks with Natalia Jagielska about London geology including dinosaurs and fossils!

Find out why the first dinosaur was called the human scrotum, why London’s buildings don’t reflect its geology and the best way to fossil hunt in the city.


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Related Blog:

Dinosaurs in Crystal Palace Park – a Virtual Tour


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Show Notes:


Hazel Baker: Hello and welcome to London Guided Walks London History podcast.  In the coming episodes, we will be sharing our love and passion for London, its people, places and history in an espresso shot with a splash of personality. For those of you who don’t know me, I am Hazel Baker, founder of London Guided Walks, providing guided walks and private tours to Londoners and visitors alike.



Natalia Jagielska is studying for a PhD in Palaeontology at the University of Edinburgh and is studying Jurassic Pterosaurs. She is also a talented Illustrator and dino consultant for






  1. London Geology
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  1. London Geology

Hazel Baker: Joining me in the studio today is Natalia Jagielska. She is studying for a PhD in palaeontology at the University of Edinburgh studying Jurassic pterosaurs. She is also a talented illustrator. So Natalia, thank you for coming today because we are going to be talking about something that I know a teeny bit about, and I know, you know a lot more, and that is geology, specifically geology of London, clay, and chalk, and the fossils and its uses.

So let’s get down and dirty with the details. 

Natalia Jagielska: I study palaeontology, which is geology, which is the study of rocks. And the best thing about London is every facet of that city is related to geology. So you look at the buildings, they are composed of limestone, which is a fossil.

various rocks you’ll look at the things that are paleogene, that’s ice age, superficial deposits. You look beneath that. and that’s Jurassic. So we have three different layers of geology you can interact with. And I just stand in one place. It’s like biblical, yeah. Made up of the world. But then also everything, to be honest, it’s also made of the same thing.

So that’s really interesting geology. It’s the principle of things stacking on top of each other . Sometimes I’m holding some things growing, changing, and the same applies through architecture, which also goes on top of each other . The best thing about architecture;. it’s use of geological stone. Bioturbation in which animals interact with the sediments, activate it and change it.

I call architecture similar because it’s us, as animals, digging up the rocks and stacking them in different positions. We are just doing extreme things by activating and altering geology. Yeah, that’s a different introduction. 

Hazel Baker: Hope that’s right. That’s a really nice way I think about it actually.

And because I’m a geocacher in my part-time job and we do a geology walk on Earth Day, and we look at things and they’re actually there are earth caches and it’s all about geology. You notice certain things when you have to really look at it because you want to get that little geocaching star.

And there were some really obvious ones in London that people could see and go “actually they’re fossils’ ‘ straight away, and people don’t expect it at all. Like maybe on the Bank of America, on NewGate Street, for example they’re really obvious ones. But thinking about how you were saying about us digging stones up and then using them again and actually creating what was underneath our feet on top of the earth and interacting with it.

That was a really nice way of thinking about it. 

Natalia Jagielska: With London, most of the building rocks actually don’t come from London because London is sitting on clay and clay is excellent for brick-making. If you bake it. it’ll make a pretty nice brick and there’s other original brick-making making in London, but clay itself is not a good building stone because it’s not a stone, it’s clay.

So lots of things we are getting it’s imported and most of the imported places come from Bath or Portland, which I’ll be explaining about because they are limestone. So it’s a rock that formed in shallow seas and a little bit of rocks a hundred million years ago and the UK was actually pretty warm, it was a tropical sea , a Mediterranean kind of setting, without a lot of calcite deposition, which usually happens around Mediterranean settings and very warm climates. And during that time, a lot of things called fusulinids, which have small bits of shell that are covered by limestone. And perform a pretty big rock, usually trapping fossils. that have lived in , that area and then

over time, those have solidified and we cut them into squares, and imported them to London. The best place for that is Portland, which is a small island south of London. The best thing about it is you can take a boat. From things to the north to this tunnel, I’m just picking it up, which makes it very handy for transport instead of dragging things across the land.

And that’s why it became very popular. Especially you have to have the Great Fire of London where you have a lot of things destroyed and architects thought. “We have to build something that will not go in flames easily” and stone doesn’t really catch fire so that you build other things. using portland limestone and wasn’t at least St Paul’s cathedral and it was small.

But sometimes when you just sit there or just look around white buildings, because it’s a very white stone and you’ll see, notice small shells usually have Aptx Ella portlandica which are just snails. and ammonites within it. Last time when I was just having a Gregg’s with my friends next to Westminster, I just thought it was sort of a random thing, close to the church that he was like, oh, I can see a Bible impression on this.

I just started looking at one and, go cover the dirt in the pavement. He was like, oh, there’s so many fossils and we start figuring out from which area of the UK the stone had come from. There are some limestones which have been imported from Italy, the same with marble as usually we just use local materials and they usually come from Bath.

When you see a yellow building that possibly comes from the bath limestone, which I happen to be studying. And if it’s white, apparently that’s what is most likely coming from Portland. And they’re all Jurassic in age . There are some fossil vertebrates and reptiles within that rock, but they’re not very common. I think there’s one church close to Westminster, which has reptiles inside it. So if you go to churches and try to find one, but otherwise they are quite rare. It’s usually invertebrates, mollusks and Ammonites and things like that. So that’s exciting.

Hazel Baker: I like the idea now of walking through Jurassic London. That’s it that’s a new thought, isn’t it? 

Natalia Jagielska: Just the fact that London is sitting on top of Jurassic deposits, more or less, Jurassic features, your sink and other things, but it’s there within the same basin.

There’s other Jurassic deposits, which yield amazing fossils. And that’s why palaeontology and the study of dinosaurs that’s our sort of came from London and it’s intellectual and elite engaged with it. Actually that Paleogeographic Society started as the London Clay Club in which people are just filtering from. London clay in search for fossils, and it sort of started from that. The first major dinosaur fossil was actually discovered in the 17th century and many people did not know about dinosaurs or extinctions back then, they thought it came from a big elephant. And one guy called it human scrotum ( Scrotum Humanum) because it looked like it and it’s actually an end of a humour of a proper dinosaur, it’s a fragment of the Megalosaurus leg bone. In the future.

The natural History of Oxford-shire. Being an Essay toward the Natural History of England. Oxford 1677

when they discovered dinosaurs were a thing a thing, they thought, oh, that human scrotum that’s fossilised, it ‘s actually not a scrotum , it’s part of a leg bone. Same as that we have big dinosaurs and things to megalosaurus. From dinosaurs which we called the Natural History Museum in London. The national History Museum in London is not built out of any stone. It’s made of terracotta, which is baked clay, They didn’t make it of limestone because limestone dissolves in rainwater and London, is rainy. Rain, usually carries acid, especially we have other Colborne Anchorage. A lot in Victorian times.

So he said we want to do something that doesn’t erode quickly. So they picked terracotta, but other buildings that are built from limestone are very prone to erosion, especially Westminster, which has a lot of problems. They had to change this limestone piece once entirely, fully. Then it was created for one different type of eroded worksite and for the 19th century, because it was so prone to erosion, thanks to the rain and its mixing with that coal from coal-burning and still ongoing problem. Limestone is affected by rain water. 

Hazel Baker: Well, that’s it.

Also the colours of London have changed throughout the years due to the popularity of whatever building materials. So you mentioned Portland stone from Portland. Christopher Wren after the great fire of London in 1666. He. Given the access to Portland stone solely, no one else could touch it.

And that was Charles the second who signed that one off. So he was rather lucky. It wasn’t him to have access to all of that building material. Then as you can see, the whiteness of St Paul’s get the draw, the whiteness of the temple bar and that, it’s Portland stone, because she’s just so gorgeously white.

And then as you were saying, The terracotta and also the the clay in building bricks, especially after the also 1815 and the population burn in the 1820s, people needed new houses, houses needed to be put up quick and bricks were a really good way of doing that because you can literally have clay right there.

And then make the bricks and build the houses right next to it. So we think that London now, when we’re walking through and it’s always a building site, isn’t it there’s always something that is being built somewhere, but it was exactly the same in Victorian times as well. And you have the two types of brick.

 Walking through, you’ll see a London stock that is yellow, grey, blue, quite a pretty brick and that’s from the clay from London. However if you look at some of the details of some of the buildings, i.e. This red brick, then that comes not from London, but usually from Leicestershire or Staffordshire, which is where I’m from originally.

So I’m very used to seeing red buildings and then coming down to London and seeing very different colours. That is once again, something very different and unique to London. Now, Natalia, you were talking about what you were studying, which is the Bath stone. So tell us a little bit about that. 

Natalia Jagielska: Okay.

So when you look at the Thames valley, you have a big basin created by London chalk then if you have something called the great lake group, which was created when you have all the small islands. In the UK, and that’s where there’s transparency by dinosaurs and pterosaurs a lot of those exposures of some skills slate, just

which is Bathonian for the Portlandia in age, which is also associated with the potent information from that information. dinosaur remains is what is actually one of the best sites in the world to see the middle Jurassic, which is a very understudied area and also birthplace of the Megalosaurus other creatures coming from that specific formation.

Bath stone is cheaper than Portland and it’s easier to cut. Everyone’s like to cut it so a lot of residential buildings and less prestigious ones, like at the back of booking a palace from it. And it looks white. A symbol of you, Parkland stone is also I’m a northerner I come from Manchester where Portland stone is used in the Liverpool docks quite extensively.

So we still have this very alien rock. That’s not a problem. He had just imparted because it looks so 

Hazel Baker: nice. It does look very nice, 

Natalia Jagielska: but it didn’t look nice. Always. When you look at historical photos, it’s very prone to sooting because when limestone reacts with water, it’s strict, this kind of grey to black is there has to be there, so in 60, 50% fifties, you have Blackish.

I’m not really nice. That’s why I only go to Edinburgh, which doesn’t have any problems. We have another standstill because it sounds done. These sorts of remains are very happy. So it looks black and classic and they say, oh, that’s the aesthetic of there. It’s meant to be a yellow, which a white is just a side effect of cold, but it looks cool.

And Gothic people, that’s everything. And that’s 

Hazel Baker: yeah. Oh, it’s fantastic. And how did everybody get all of these different stones to London? Because we have the canals. But then you’ve got the railways coming in in the late 1830s and really mainly in the 1840s. So was it coming by rail or was it coming by sea and then not the terms?

What, how charming would they be? 

Natalia Jagielska: Both by, right up and the famous, and that’s what makes a person so special because it’s on a small island, so it’s never easy to pass on something as heavy as it is. So just easier to drag around, but also. Same with the bath. It was actually, those materials were carried over even during development times.

So people knew how to transport them. Not exactly at the same volume. You say it’s crunchy, but they’re still transporting those things and. It’s still going on the Alvin stone, which is the company that was still transported by rail boat. But if you might cut that off because I’m not unexpected, I’m transformed over them.

Hazel Baker: And if you’re building buildings from the start and they are big, significant buildings, which means you need them. I 

Natalia Jagielska: know, even when you lived there, because poplin stories also in New York. So I assume it’s not a big leap to export it. Let’s just put it on a big tanker and send it across the Atlantic shutter, 

Hazel Baker: Iceland.

But I do. I do love the idea of being able to play with different types of building materials as well. I can never understand why they built the houses of parliament Westminster with such a rock that is known for. Reduce or amongst the rain now, admittedly London has less rainfall than Rome.

I’ll just want to put that out there. It’s just that it just seems that. It has been wet here for longer. We don’t have the heat to episode all the rain. I say London 

Natalia Jagielska: seems like a tropical place compared to Manchester. It rings me chest and unstuck. And you go to the head bride, which is suddenly dry. It’s just mentioned that in Wales, they just counted.

Everybody thinks, oh, your case, rainy. No, it just railed on them and tested everybody else. They take all the 

Hazel Baker: beading. Yeah. I yes, you’re talking to a girl who first ever went to Manchester, wearing blue suede shoes. I remember that trip very well. So thinking about London, and the colours.

So you’ve got the 

sand-coloured limestone you’ve got the yellow, you’ve got the Portland stone with the white, you’ve got the terracotta and the red brick. You’ve got the yellow grey London stock as well. That’s technical to London, 

Natalia Jagielska: isn’t it? Cities are usually made of things they might sit on.

For example, Aberdeen is not the greatest city because it’s all probably right from the product. It’s sitting on a grant formation. Same with. Paris Lieutenant limestone, which is in the Paris basin, everything parcels, this creamy yellowy thing, because it’s sitting on the quarry, it’s making itself similar to London because they are both lime, some base is just house yellowish.

Lama has this.

it looks kind of like marble, like until of course you have some other inputs. You have other granite, which comes from Cornwall. Is the carnage branded more darkish with some shiny material? And they usually use us as pedestals for a lot of seizures and you have some marble that has been booked for a little bit longer in his processes, as it has been metamorphosed as we call it, it is very multicoloured until about any pin drop on anything.

It’s just the rocks it’s using. Interesting because like it’s created authentic, sounding golf, so things he hasn’t parted, which is 

Hazel Baker: great. agree. And I go back to the fossils that you were mentioning, what fossil was it that you said that you could see. Immature. 

Natalia Jagielska: It’s an unidentified reptile.

Eh, what if you’re going to search for things? Look for things that look like screwdrivers. So just because they are gastro ports, they are basically snails and there’s also some other resources. I am very bad, so they are not the most exciting things, but sometimes. It happens. Pupils find actual fossils and look a couple times at some things just that’s just missing, eh, people going.

And so you have to look off, you might find some kind of big advertisements for me, especially in newer buildings, just go and sink a drought marble, which is the most popular, important story we have from Germany, at least in Edinburgh and new buildings. And you have a lot of amazing Ammonite sponges, and I’m looking out, maybe I’ll throw SRR.

I’ll be very excited. It’s pretty likely, there’s some cases of people finding whale bones or bigger bones in their marbles or kitchen puddles. And yeah. 

Hazel Baker: My goodness and I, while I was thinking I was really smart because I’ve seen, I found some links to shells in I think it was limestone. It’s the base of the statue of Charles the first, which is just at the bottom of Trafalgar square.

It was the very first renascence question statue that we had in the country. And when you have a look at it more closely, you can see how the Walter, over those hundreds of years, Has it worn it all down and you can actually when you touch it the oyster shell is in, looks like a horseshoe because obviously it’s not all available.

It’s just imagining. Yeah. 

Natalia Jagielska: Yeah. It might be a Bible. Most of the things we are seeing, it’s becoming prevalent on their watch formation, which is usually used for corrective purposes, because you’ve started and have all the fossils. It also other fossils are created from aragonite, which is not very stable.

So changes a form as it fossilizes. So usually we just see Casco things. So we’re not actual fossils, just gaps they left behind. It’s like chemically altered versions of them. So it looks more. Office holes, rabbit, actual full foster ribs, other things. So it’s pretty possibly up to something.

And if you have time, you can go to the Green Park tube station because it’s entire femur length. Limestone has this kind of big artwork showing different gastro ports on top of it. And then it goes like the Cooper Oak, I think it’s west. And you have that. Ralph bumper at Memorial, which is also a creative port of life.

So go down the memorials and find some you about to spend some fossils. 

Hazel Baker: I’m really inspired to go on a fossil hunt now. And I think you have given me a tool which is going to help that, and that’s the London pavement geology. They have. I downloaded it when she gave me the link and I haven’t been stopped.

I’ve stopped playing with it since actually. And now I can just imagine getting my little nephew back into London and I think we should go on a fossil hunt. That sounds like a lot of fun. Actually. I think it’s something that all ages can do. 

Natalia Jagielska: And the best thing about it is that we can ask her. So if you’ve spotted something you can contribute.

First. I found a fossil fish in Caitlin’s pavements done in Edinburgh. Nobody knew about it, so you might be the auctioneer at the best thing we’ve looked at. This challenge is hard, so we go fossil fuel, but there’s so many fossil prose rocks in cities already. So be a pathologist and to crawl around London and look up differences.

Pavements since Carlos is on the streets, because he might find something cool. It’s 

Hazel Baker: yes, I can. Can I expect this to be taking up a lot of my spare time now. Thank you very much for that. I don’t think it’s a problem. Making geological history. 

Natalia Jagielska: Yeah, you can always go to national history, museums, London and grand museums.

And look at actual fossils. 

Hazel Baker: I have done that and I must admit they have huge Ammonites. The biggest one I’ve seen in England. When I went to Morocco they had some gigantic ones on display. I really could not believe that these things were real. It just goes to show you we are as people and also a space and a little dot in time. Really compared to everything else that has been on this earth, it is quite amazing.

Isn’t it? It is also 

Natalia Jagielska: how we should shoot in a short amount of time, how much we have changed it. After all, we dig the different things that were in the deficit for millions of years, several years. I don’t know, shifting the power in which we like. I also just can see how big they are, because I’m nice with snacks, full things that live in the seat.

So you can imagine how big those other,

Hazel Baker: I have nightmares now about that. Thank you very much. For our listeners I’m going to put the links that Medallia is shared with me onto the show notes as well, where the link to Natalia’s Twitter account, where she shared some really amazing stuff, including her registrations and also, if you want to hear a little bit more about that the the ice age and the change, but more importantly, the animals that lived in what was now London, then you can listen to episode two of our podcast called fantastic beasts. And then you will hear all about giant Elks and wooly mammoths.

Hazel Baker: Hippos into Trafalgar square; brilliant. 

And continuing on to our dinosaur theme, then episode 47, if you haven’t listened to that so far, then get onto it. It is Victorian dinosaurs in crystal palace park, where I talked to Sarah slaughter about these wonderful life-size dinosaurs that they’ve got there and which you can visit absolutely free. 

That’s all we’ve got time for now. Thanks very much for joining us. If you have any suggestions on themes or indeed no of anybody, who’d be a wonderful guest on our

London history podcast, then please do get in touch. 

You can do that. By going to our website and click contact us

Thanks again. Till next time. 


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