Volcanic islands tell their own story — just look at the rocks.

Yes, and you don’t need a degree to read them.

Most islands that aren’t continental fragments are volcanic. The markers are usually right there in plain sight: lava flows, volcanic cones, crater lakes, and layers of ash. If you’re on Hawaii, you can walk on fresh pahoehoe lava. In the Galápagos, the older islands have eroded tuff cones and the younger ones are still barren basalt. Iceland is basically a giant geological billboard with rift valleys and steaming vents.

For coral atolls, the markers are underwater — reefs that grew on top of sinking volcanoes. But you can still see the shape: a ring of islands around a central lagoon. That’s the old volcano’s footprint.

Geological markers are usually obvious once you know what you’re looking for. A dark, jagged coastline? Volcanic. Layers of limestone on a hilltop? Old reef that got pushed up. The islands themselves are the evidence.

The best markers are the ones you can touch.