Our third stop of the day was about the ground itself. We had spent the morning on people, the ones who may have come first and the ones who scratched a living out of turf and stone, and in the afternoon we went to look at the thing all of them were living on top of. The Lava Centre, in Hvolsvöllur, is an exhibition about the volcanoes that made this island and are still making it, and it was the right place to end a day of learning.

The best part was the film. It runs through the recent eruptions in Iceland, one after another, and seeing them listed with their years is genuinely hard to take in. Eyjafjallajökull in 2010, the one that stopped air travel across Europe. Grímsvötn in 2011, the largest at that volcano in a hundred and forty years. Holuhraun in 2014, a vast outpouring of lava in the highlands. And then the Reykjanes Peninsula, near Reykjavík, which had not erupted in about eight hundred and fifteen years and then woke up in 2021 at Fagradalsfjall, and has erupted again and again since, a whole series of eruptions right up to the present. The list just kept going. Sitting there watching the dates stack up, you understand that in Iceland an eruption is not a rare historical event. It is something that happens every few years, sometimes every few months.

One number from the exhibition stays with you more than the rest. Over the last five hundred years, this one small island has produced about a third of all the lava that has erupted anywhere on Earth. A third. A country of a few hundred thousand people, a speck in the North Atlantic, has poured out a third of the whole planet’s lava in that time. On average there has been a major eruption here every five years or so since the Middle Ages, and thirty-eight in the last hundred years alone. We wrote about why this island is so restless in our geology primer, and here was the number that puts it beyond doubt. This is not a country that has volcanoes. This is a country that is one.

Around the film the exhibition explains the how and why, and it is hands-on and well done. Iceland sits on the boundary between two tectonic plates that are pulling apart, and on top of a hot spot, a plume of heat rising from deep in the earth. That combination is why there is an island here at all, and why it is so restless, and it is the same thing we laid out in our geology primer. The displays walk you through magma, the different kinds of eruption, the earthquakes that come before, and the way the ground swells and cracks as molten rock forces its way up. It ties together a lot of what we had been seeing all over the country, the lava fields, the geothermal steam, the black sand, the calderas, back to the single engine underneath all of it.