We spent a few more days hiking around in Nepal but yesterday we boarded a plane set for Rancagura near the Andes Mountains. We made it to Chile yesterday and spent this morning visiting museums until lunch time. We then gathered up our ski equipment and went into the Andes at about 34 deg 4'30.75"S and 69 deg 550'26.99"W to look for some powder. The skiing was great and when we were all exhausted we went into the lodge for a cup of hot chocolate. John took the time to explain the science of the Andes.
Similar to the Himalayas, the Andes are a convergent boundary so the plates are moving toward each other but they involve subduction and oceanic crust. I explained a little about convergent subduction boundaries in my last post but after visiting the Andes I have a lot more to explain. When two plates hit in a spot where there is continental crust on one plate and oceanic crust on the other, the oceanic crust subducts under the continental crust because it is thinner and less dense. As the oceanic crusts descends into the mantel, it heats up and around 100 miles under the plate starts to melt. This melting results in magma chamber that rises up to the surface and causes volcanic eruptions. According to John there are many volcanoes in the Andes as a result of the Nazca plate subducting under the South American plate. This subduction created the volcanic Andes Mountains and is continuing at a rate of 3 inches per year.
After our ski trip we headed to our hotel for a big group dinner and then went to bed awaiting our next tectonic adventure.
- Katherine
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