Galápagos Fumaroles
As our chiva (rustic Ecuadorian bus) winds its way into the highlands, the vegetation condenses and humid fog thickens into an almost oppressive drizzle. A cowboy and six horses emerge from the shroud and we stop briefly to drop off the group of horse-riders. The rest of us continue in the chiva, winding up a track of fresh volcanic rock and slippery clay mud. A dense growth of guava and Darwin bush swamps the surrounding land.
The view from the edge of the caldera is limited to a white fog, and, after dismounting our transport, we stop briefly at an information board to imagine what we, on a clearer day, would have seen. With a 10 km diameter but only 100 m in depth, this is the second largest caldera in the world, estimated to be 535000 years old. There is no time to waste, so we start down the steps into the caldera.
This is a textbook example of primary succession in reverse. We pass from the treed outer slopes over the lip and into a shrubland of ferns and rosemary. Deeper into the caldera, these shrubs peter out into grasses, followed by a margin of lichens and eventually, bare rock spans the fumarole field.
At this point, we can smell the sulfur (or rather, hydrogen sulfide, as sulfur itself has no scent). Most infamous for being reminiscent of rotten eggs, sulfuric compounds are responsible for the scent of gas, skunk scent, bad breath, grapefruits, and garlic. Today, the wind blows just enough to keep the overpowering stench at bay, and we choose not to wear the masks we brought.
Our guide stops to explain how churning convection currents below the earth’s crust form hotspots where magma builds and rises like a pimple under the skin of our planet. A magma chamber then forms, and fissures release lava across the island. When the pressure on the chamber is eased, the crust above collapses in on itself, hollowing out the top of the mountain and leaving a caldera. He likens this process to boiling milk. How, when you cool the milk, a skin forms, and how we are akin to tiny flies sitting on the fragile surface. Ending on an ominous note, he asked us to think about what happens to the fly when you start to re-heat the milk.
The sulfur mines are now just a short uphill hike away. The terrain consists of small rocks, most white but some close to baby blue and others almost blush pink. Porus chunks of rock – lava bombs – are strewn across the landscape as a reminder of the battlefield this area can become.
Of course, we are all intrigued to see the sulfer itself. Large and crystalline, sickly yellow yet strangely edible-looking, sulfur is the fifth most common element on earth (by mass). It is an essential component of the planet we live on, yet looks so extra-terrestrial in this alien landscape. Clouds of steam and volcanic gases billow out of vents, gradually breaking down the surrounding rock and depositing minerals. Below this geological spectacle we find a small cave of sulfur, hot air streaming from its mouth. We take it in turns to inspect, careful not the touch the fragile sculpture.
The hike back to the lip of the caldera is surreal, moving away from the science fiction landscape of raw elements and transient rock to the developing stability of vegetation. We arrive just in time to meet the horse riders, trotting in from their trek around the edge of the caldera. Sharing lunch, we exchange stories of galloping and exploring this unfamiliar landscape. After an adventurous morning, an afternoon beer in town is well-earned.
