Colca Canyon, PeruThis is one of two gigantic canyons found on the western side of the Andes Mountai

Colca Canyon, PeruThis is one of two gigantic canyons found on the western side of the Andes Mountains of Peru. Colca Canyon reaches depths of over 3 kilometers beneath its rim, more than twice the depth of the Grand Canyon in Arizona.The Colca begins on the edges of the Altiplano, a high desert plateau in the Andes that cuts across Bolivia, Peru, and Chile. It is being pushed up by subduction of the Nazca plate beneath South America, including in parts subduction of a ridge on the ocean floor that is helping push the continent up further (see my recent post here: https://tmblr.co/Zyv2JsYv1SocSy00).This plateau is thought to have been uplifted starting in the Miocene, just under 25 million years ago. The surrounding rocks were capped by hard volcanic rocks, including a major ignimbrite (an ash deposit from a large, explosive volcanic eruption). Sometime between 12 and 8 million years ago, erosion was able to punch through this ignimbrite at 2 spots, one of which localized water flow right here and began cutting its way down. Erosion has removed the edges of the Altiplano at this spot, taking the river down from the high country and cutting through the surrounding sedimentary and eventually metamorphic rocks.Erosion was aided by a wetter climate in the Andes around 7 million years ago, prior to the onset of the modern glaciations that helped this part of the world dry out. As the plateau continued being uplifted, these rivers cut down, each of them removing nearly 2000 cubic kilometers of sediment.Today this canyon is one of Peru’s most visited natural features. It hosts a variety of cultures and a number of native species, including the Andean Condor.-JBBImage credit:https://commons.wikimedia.org/wiki/File:Colca_Canyon,_Chivay,_Peru_(Unsplash).jpgReferences:https://www.geocaching.com/geocache/GC1HKWF_colca-canyonhttp://geomorphology.sese.asu.edu/Papers/Thouret_etal_EPSL2007.pdf -- source link

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