When you finally land in the Galapagos Islands, your eye is immediately drawn up and out. Up to the sky, to see the many birds soaring and whizzing past—was that a Nazca boobie? Was it a rare lava gull? And out, to scan the ocean’s horizon for a whale’s spout or surfacing sea turtle.

But don’t forget to look down.

The Galapagos Islands were formed millions of years ago as lava rushed from the earth into the sea. In the Galapagos, one can find two types of basaltic lava: “aa” and “pahoehoe.”

© Beth Cericola / WWF-US

Aa (“ah-ah”) lava moves more slowly, allowing gases more time to bubble and explode through its cooling crust. This lava creates sharp, jagged chunks that look an awful lot like gravel for thick-skinned giants. After a hike out on an aa lava field, it’s easy to see how this lava type got its name.

Pahoehoe lava is less viscous and faster to flow. As the surface of pahoehoe lava cools, it is pushed and folded into itself, forming smooth wrinkles and undulating curves. It’s easy to get lost into the soft lines of solid, ancient rock.

The Galapagos Islands still boast active volcanoes, sculpting new formations for you to discover.

© Beth Cericola / WWF-US

By Beth Cericola, WWF

Travel to Galapagos with Nat Hab and WWF.