Did you know the buildings in your city could be hiding ancient secrets? Urban geology reveals a fascinating world of fossils, rocks, and history right under our feet. But here's where it gets controversial: some people think these fossils are fake, carved into the stone for decoration. Let's dive into this captivating field with geologist Ruth Siddall, who’s turning city walks into prehistoric adventures.
In the bustling heart of London, near the iconic St Paul's Cathedral, Siddall points out a greyish-brown shape embedded in a building’s limestone. It’s a fossil from the Jurassic period, and it’s not just any fossil—it might be a bone from an ancient creature, possibly even a pterosaur. Most people rush past such details, but Siddall, an 'urban geologist,' specializes in uncovering these hidden gems. She’s here to show us that cities are not just concrete jungles but treasure troves of Earth’s history.
But here’s the part most people miss: the stones in our cities tell stories of both geology and human history. Take Portland Stone, for example. This creamy-white limestone, quarried from Dorset, became a symbol of British architecture after the Great Fire of London in 1666. It was used to rebuild St Paul's Cathedral and later found its way into Buckingham Palace and even the United Nations General Assembly Building in New York. Its durability and marble-like appearance made it a global favorite, but its fossil content—shells, snails, and occasional ammonites—often leads people to doubt its authenticity. Siddall recalls a security guard in Paternoster Square who insisted the fossils were fake, pressed into the stone. But these fossils are real, around 150 million years old, and they’re everywhere if you know where to look.
Urban geology isn’t just about identifying rocks; it’s about understanding human choices. Why did Victorian pubs in London use smooth granite? Siddall explains it was a practical choice—easy to clean after rowdy nights—but also a statement of class, less elitist than marble. Similarly, the Washington Monument in the U.S. has a marble 'unconformity' halfway up, not a design flaw but a historical marker of the American Civil War halting its construction.
And this is the part that sparks debate: What stories are we missing in our own cities? As we walk, Siddall points out the eclectic stones on the plaza near St Paul’s. These aren’t random—they’re remnants of the medieval cathedral destroyed in the Great Fire of 1666, recycled into the new plaza. Each stone has lived three lives: formed in the Earth, built into a cathedral, and now paving a modern square. It’s a reminder that cities are layered with history, waiting to be discovered.
As our tour ends, I realize how much I’ve overlooked in my own city. Urban geology invites us to slow down and see the world differently. What secrets lie in your city’s stones? Are the fossils real, or are they man-made decorations? And what does your city’s architecture reveal about its past? Let’s start looking closer—and maybe even start a discussion in the comments. What hidden histories have you noticed in your urban environment?
