There are many reasons why we’re building our firework volcano, but another reason is there there isn’t already a volcano in Norfolk. But why aren’t there any? I’m sure that this question has led to many a sleepless night for you all, so I’ll try and explain why. Let’s first start with the United Kingdom as a whole.
There are some volcanoes in the UK, but they’re all extinct, meaning that they’re unlikely to erupt again – which is good news, because we’re a small island, and adding a volcano to the mix would probably not be such a good idea. We’ve had big volcanoes in the past though, for example, Snowdonia would not have been as nice a place to visit around 450 million years ago. In fact, it would have been pretty toasty!
We haven’t had any volcanoes for a while (about 55 million years ago) because we’re not close to the edges of the tectonic plates that make up the Earth. It’s at these boundaries that volcanoes tend to form. As you can see from the picture below, the UK is safely tucked away inside the Eurasian Plate.
When tectonic plates converge (come together) or diverge (move apart) you tend to get volcanism. When tectonic plates converge, if one plate is lighter (e.g. made up of continental crust) and the other is denser (e.g. made up of oceanic crust), then the denser plate is subducted and forced down to great depths. Here there are high temperatures and pressure which cause the rock to melt, forming magma which rises to the surface creating volcanoes – just look at the Andes! When plates diverge, you also get magma forming, but a lot of this activity is on the seafloor, and when it erupts, it forms new oceanic crust. But if it’s above the ground (like at the East African Rift) then you do get volcanoes. You can also get volcanoes above mantle “hotspots” in the center of plates, for example Hawaii – but luckily there isn’t one underneath the UK! When tectonic plates slide past each other, you don’t normally get magma forming, but you do get earthquakes – for example, along the San Andreas Fault.
So, we’re pretty safe from volcanoes right now – but why aren’t there any extinct volcanoes in Norfolk? The oldest rocks that are exposed in Norfolk are Jurassic in age (161 million years old) and the geological record of rocks since then has been made up entirely of sedimentary rocks. It just so happens that Norfolk has never been too close to any of the volcanic activity that has taken place in the UK. Instead, it has been covered by seas of varying depths, or exposed to the air and covered by rivers. But even though there are no volcanoes in Norfolk, there is still plenty of interesting geology to be found. Just look at the cliffs at Hunstanton or all the fossils you could be looking for right now!
So, to see a volcano in Norfolk, you’ll just have to come and see our firework volcano on the 28th of September. See you then!