A Naturalist's Pilgrimage to the Galapagos
Smithsonian's Laura Helmuth vacationed in the Galapagos Islands and returned with even more respect for Charles Darwin
- By Laura Helmuth
- Smithsonian.com, January 30, 2009
The archipelago of 19 islands was and is being created by a "hotspot" where magma bursts through Earth's crust. The hotspot stays in one place, but the oceanic plate through which it erupts is creeping steadily eastward. So the islands on the eastern side of the archipelago were built up earlier--a few million years ago--than the ones on the west, most of which are still erupting.
As if Darwin didn't do enough for science with the theory of evolution by natural selection, he also figured out the life history of oceanic islands. He realized that such islands start as volcano peaks, erode into flatter islands as their volcano ceases spewing lava, and eventually sink into the sea surrounded by an atoll of coral that grew on the flanks of the volcano.
This caldera at the top of Sierra Negra volcano on Isabela last erupted in 2005.
So the islands emerged from the sea as molten rock--perfectly sterile.