Day 21 - How did the Galápagos form?

Many groups of islands, such as Hawaii and Maldives, form long chains of islands springing up one after another. Other groups of islands, such as the Galápagos Islands, create a cluster of islands, forming no distinct line. So, why are the Galápagos in a seemingly random cluster, and not in a neat, little line? 

Groups of islands are most often created by volcanic activity--volcanoes erupting underwater and creating masses of land rising from the ocean's floor. Most communities of islands are created from one hot-spot. For example, Hawaii only needed one hot-spot create its long chain of islands. However, this seems nonsensical. How can one volcanic hot-spot lead to the formation of several islands? 

This seemingly impossible feat is accomplished by the movement of the Earth's tectonic plates. These plates make up the Earth's outer surface and are constantly--but very slowly--moving. As the plates crawl over a volcanic hot spot, the eruptions bursting through the Earth's crust will shift, creating the neat line of islands over millions of years. 

But this doesn't lend any help to answering the question of why the Galápagos was formed in such a random pattern. The answer is due to interactions between different tectonic plates on the Earth's surface. You can see in the picture below that the islands of Hawaii are located in the middle of a huge tectonic plate where little interaction between plates would occur. This means that the movement of the plate will be mostly lateral, creating a string of islands. However, in the case of the Galápagos, located on the northwest edge of the Nazca plate, there are constant interactions with both the Cocos plate and the Pacific plate. As a result, the constant battle between these three plates creates a movement that is not lateral, but more like a three person game of tug-of-war. 

The movement of these plates can also explain the different relative ages of the island. The picture above shows how the Nezca plate is slowly moving to the east, pulling the older islands eastwards. Following the islands from east to west, the oldest islands can be identified as San Cristobal and Española and the newest islands in the group appear to be Isabela and Fernandina. 

Several times throughout our trip we have had the opportunity to see 3D maps much cooler than the one above (we didn't take any pictures of them oops), and have gotten an explanation on why the islands formed the way they did. We thought it was super interesting and just wanted to give an explanation on the formation of the islands. Additionally, we think it is fascinating that we are getting to go to the oldest island, San Cristobal; a middle aged island, Santa Cruz; and one of the youngest islands, Isabela. We leave for Isabela tomorrow, and we will update you blog readers on some of the differences we notice between the different aged islands! 

- Grace + Sarah 

We did some research for this blog post so here are our sources for anyone interested: 

https://www.galapagos.org/about_galapagos/history/

https://education.nationalgeographic.org/resource/archipelago/

https://oceanservice.noaa.gov/facts/archipelago.html

https://www.nps.gov/features/yell/ofvec/exhibits/eruption/volcanoes/hotspot.htm