The marine iguana rarely strays far from its watery habitat, but it comes ashore to warm itself in the sun. The creature’s claws tightly grasp the rough volcanic rock. A wave crashes over its black-green body, over the ridge of pointy spikes rising from its spine, over reptilian eyes that seem to register nothing. Dripping now with the cold water of the Pacific Ocean, the animal extends another foot forward. Its long digits, sensing like a beetle’s antennae, feel around for a new place to grab hold. Slowly it pulls itself out of the cold sea and up to a ropy flow of lava rock to absorb the heat of the equatorial sun. This scene could be millions of years old, but it is actually late in 1999 — a date that feels strangely arbitrary while watching a dinosaur-like marine iguana crawl from the brine onto a volcano. This particular marine iguana clambers on the edge of Fernandina, the youngest of the 14 Galápagos Islands. Other marine iguanas perch like gargoyles on the edges of all the islands in this chain, the only place in the world the species is found. According to some biologists, these algae eating reptiles split from their land dwelling cousins some 15 million years ago. Yet the oldest existing Galápagos Island is just more than three million years old. Blue-footed boobies are just one of myriad bird species found on the islands. So how does science explain the existence of an animal, slowly evolving for perhaps 15 million years, on a series of islands only a few million years old? The answer lies in the geologic history of the Galápagos and the marine iguana’s strange method of distribution. Fernandina rises ghost-like out of the eastern Pacific. Veils of rough basalt cascade down its steep upper slopes while solid rivers of the black rock braid down its gentle lower ones. Fields of cracked and broken lava, frozen in spatters and ropy flows, surround the base of the peak and end abruptly at the shore. Under the water, its flanks drop thousands of feet to the sea floor. The islands sit over the base of a great plume of molten rock rising from deep within the earth. Known as a "hot spot," this column of magma feeds the volcanoes that make up the famous Galápagos Islands, 600 miles west of Ecuador. The surface of the planet is sheathed with a broken collection of thin rock shells known as tectonic plates, which drift over such plumes. The Galápagos Islands ride on a slow moving oceanic plate called the Nazca. This plate drifts eastward over the hot spot like a sheet of metal slowly pulled over a cutting torch. A scar of volcanoes is left in its wake. The islands, born of magma, build gradually as the plate drifts over the swell of the plume. Fernandina is located directly over the hot spot and, at about one million years old, is the youngest island of this chain. To the east of this mighty mountain, older slowly cooling islands gently recede back into the sea as time, and distance, remove them from the hot spot. Submerged islands have been found some 500 miles and nearly 15 million years away, in a cold graveyard beneath the sea. The ancient relics sit on the western edge of the Pacific Ring of Fire, the volcanic border outlining the Pacific basin. They will eventually sink down under the South American continent as the tectonic plate recycles back into the earth.