Galapagos Geology




 The Geology of the Galapagos

By Sam Beesley









The Galapagos islands consist of many different islands formed by volcanoes which were produced by the tectonic plate (nazca plateau) passing over a hot spot in the earth's mantle. A hot spot is when the earth’s crust gets really thin allowing magma from the mantle to rise and form volcanoes. Hawaii was also formed in this way. 


The Galapagos islands are slowly moving eastward and diving below the sea when they hit the tectonic plate that formed the Andes mountains.  This means that the eastern islands (San Cristóbal and Española) are roughly five million years older than the western islands (Isabela and Fernandina) Which also means that there have been other islands that are currently either under the sea or in “Liquid hot Magma”.




The volcanoes on the Galapagos islands are not constructed like most volcanoes. While most are more cone shaped, the volcanoes on the Galapagos have some of the widest tops in the world. The Sierra Negra, a volcanic mountain on Isla Isabela has the second largest caldera on earth. 



The caldera of Sierra Negra


The lava is also different, with at least 3 different types: The Ah Ah lava which is so sharp that if you lean up against it you’ll get cut, The Rope lava (Pahoehoe) which looks like ropes, and the red lava, which is just REALLY old lava that has turned a rusty color due to the oxidation of the iron in the rock.  The lava rock on the Galapagos islands is basalt, which coincidentally is the same rock found on the moon.  


Ah Ah Lava (I think)



Pahoehoe (easy walking)


Oxidized lava


The volcanoes of the Galapagos are all separated by Ah Ah lava, which being sharp,  separates animals causing isolation and eventually speciation.  For example, tortoises can’t cross the Ah Ah lava,  which is why there are multiple species of tortoises on one island.  When an island is originally created it only has lava on the surface, which means that very few plants and animals survive there due to the lack of nutrients found on young islands. 


Lava tubes are created when lava flows down the side of a volcano and the outer crust hardens. This causes a tube that is then preserved for centuries.  The rope lava is created when lava is flowing over flat ground and the skin hardens slightly, this creates an appearance like coiled rope.  


Lava tubes

Comments

  1. UnknownFebruary 27, 2022 at 8:15 PM

    Hi Sam, I’m enjoying your discoveries from afar and thank you for sharing. It seems you are thriving in a pretty amazing spot on the planet. I found the idea of speciation to be interesting and had no idea there could be different kinds of lava in one area. Your explanation makes sense. Enjoy your adventure and remember every single day! Lots of love to you and your family.
    Best, Pam

    ReplyDelete
    Replies
    1. SusanMarch 5, 2022 at 7:04 AM

      Thanks for reading Pam, I hope you’re doing well. Sam

      Delete
  2. Tim JesterMarch 4, 2022 at 10:48 PM

    Thanks, Sam. I learned a lot about lava and the geology of Galapagos.
    Tim

    ReplyDelete
  3. UnknownMarch 9, 2022 at 7:24 PM

    Sam: I had no understanding of the different types of volcanic rock, and how they developed, until I saw this blog by you. The photos are really neat and great at showing us the differences. The blue sky against these different lava formations is gorgeous, and the size of that caldera is unbelievable!
    Muchas gracias! Irene

    ReplyDelete
  4. Michael RymerMarch 13, 2022 at 1:10 PM

    Thanks for this, Sam - I learned a lot from this post. Great photos, too.

    ReplyDelete

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