BORN FROM FIRE

Galapagos Geology

Magma rises from the Earths’ core, breaking through its crust, and a torrent of lava erupts to form strange landscapes. On the surface, calderas, lava fields & tubes, black sand beaches, and puffing volcanic peaks are created while rich volcanic soil feeds weird and wonderful flora. Such geological processes tell a great deal of stories about the world we live in, stories that began millions & millions of years ago.

More than 10 million years ago, volcanic eruptions on the ocean floor started spewing lava until more than 3 kilometers of thick lava piled up, forming the one big Platform on which now sits a chain of islands and underwater mountains. Over time (not more than 3 million years ago), tips of the seamounts reached the ocean’s surface and the islands were born. In geological terms, they’re still relatively young. Today, with six active volcanoes and more than fifty eruptions in the last two centuries, the islands are one of the most volcanically active island groups in the world!

Unlike other volcanic islands, the Galapagos islands don’t align with the tectonic plate underneath them so neatly, which puzzles geologists for various reasons, adding to that the lack of a clear pattern of age between the volcanoes suggests a complicated history of creation. Several hypothesis were proposed involving the interaction of Plate Tectonics, Mantle Plumes, and Hot Spot Volcanism but how exactly the islands were formed remains a geological mystery. So let’s delve deep, way deep below the ocean floor, to where all that Magma comes from and try to understand what happens down there.

Magma can vary in temperature. Exceptionally hot magma resides in what’s called a mantle plume. Excessive heat causes Earths’ rocky crust to melt, allowing the Magma to pierce through the seafloor and form seamounts and volcanoes. The area above all of this volcanic activity is called a hotspot and the Galapagos is located over one. Over millennia, hotspots feed magma into submarine volcanos until they emerge from the ocean and form volcanic islands. While mantle plumes & hotspots are relatively stationary, tectonic plates are not. As volcanoes move with the tectonic plates, away from the magma feeding hotspots, they cool & subside creating older islands and atolls.

The Nazca Plate, on which the Galapagos sits, moves eastward across the hotspot. New islands form above the hotspot while older volcanoes & islands drift away; some of the original islands have long since receded beneath the ocean’s surface while some of the younger ones are still in the process of being made to the northwest of them, eventually though (not in any of our lifetimes), the islands will be subsumed beneath the South American continent and disappear!

Over millions of years, all of these processes have created a cluster of unique volcanic islands which now make up the Galapagos archipelago. The islands’ extreme isolation made getting there very difficult. The species of plants and animals that did manage to float, drift, or fly here had to adapt and survive in an extremely harsh environment. This adaptation process has been taking place over thousands of years, but in the last 500 years that pace changed dramatically. Humans stumbled on to the islands, forever changing the ecosystem, and our understanding of the natural world has never been the same.