If these rocks resemble a pile of cannon balls, it’s with good reason. They’re actually known as volcano bombs, and they spewed out of Iceland’s volcano Eldfell in its first (and only) eruption in 1973. The rocks formed from molten lava, which cooled and solidified rapidly whilst still flying through the air.
These are just a minute fraction of the amount that came raining down on the nearby town. Imagine six months of these rocks pelting down, and you’ll have a good idea of what Heimaey had to endure. The eruption was completely unexpected, but thanks to a lucky combination of factors, all but one of Heimaey’s residents managed to survive, fleeing the island on the town’s fishing boats. Though the constant onslaught of these bombs, mixed with molten lava streams, left most with no homes to come back to.
When the residents did come back, they found that the island had grown by 2km² thanks to the constant lava flow, and volcano bombs were dotted everywhere. The rocks are a rainbow of colours, just like Eldfell volcano itself, and these hint at the minerals within the volcano’s churning lava. Yellows are thanks to the presence of sulfur, reds are due to iron and greens come from copper. Some rocks are completely solid, whereas others have a bubbly Aero-like consistency. These bubbles form due to trapped gases, such as carbon dioxide, which didn’t have time to escape into the air before the molten magma cooled and solidified.
Volcano bombs aren’t unique to Heimaey – if you keep an eye out you can spot them in almost every lava field in Iceland. In fact, Iceland has some awesome rocks. But its here in Heimaey, piled up high as if ready for battle with the town below, that the term ‘bomb’ takes on added significance. All that’s missing is a cannon.
- To see these volcano bombs, you’ll have to hike up Eldfell volcano. It’s short, but steep! Though it should be doable even for those with quite low fitness, possibly with a number of stops along the way 🙂 – budget about 30 minutes to get to the top from the hike’s starting point.
- Heimaey is a small island, but it packs a punch. Besides volcano bombs, it has black sand beaches, puffins, Icelandic horses and beautiful vistas. It was actually one of my favourite places in Iceland, so I would recommend staying at least one night. I’ve written more about it here. I stayed in Guesthouse Hamar and can thoroughly recommend it – comfy beds, beautiful views of the volcano, and the hotel staff were super helpful.
- Heimaey can be reached by ferry from Landeyjahöfn, which takes about an hour. I’ve mapped locations below. (Heimaey is part of the Westman Islands, also known as Vestmannaeyjar)