Science Advances<\/a>.<\/p>\nThe canyons carved into the 3.7-kilometer Andean Plateau are 2-3 kilometers deep. For comparison, even at its deepest, the Grand Canyon spans less than 2 km from top to bottom. The structures are so vast, McQuarrie says, that she couldn\u2019t capture its scope on camera. \u201cWe were there, I know it\u2019s there, but the pictures don\u2019t convey the scale of the full canyon.\u201d<\/p>\n
There have been two predominant theories for the processes that led to the formation of the canyons: Either they were the result of an abrupt event, such as the rapid rise of earth caused by an earthquake, or they were the result of a period of heavy rainfall, increasing the amount of water carving its way through the plateau. The researchers wanted to determine which of the two explanations was likely to be correct.<\/p>\n
It turned out, there might be a third explanation.<\/p>\n
The research team, which included first author Jennie Plasterr, a graduate student working in McQuarrie\u2019s lab, tested both scenarios using computer modeling. They ran models incorporating current knowledge about historical tectonic activity in the region and recent estimates about climate and precipitation.<\/p>\n
\u201cWhat we found is that neither of the two prior explanations were likely the primary driver of the canyon incision,\u201d McQuarrie says. \u201cThey were both important contributors, but the main thing that allowed for the incision of this deep canyon was the ability of a river to capture another river.\u201d<\/p>\n
River capture occurs when the erosional power of a river carves the surrounding land until it ultimately breaches the ridgeline that separates it from another river. The water from the second river is diverted to the first, increasing its erosional power and its ability to dramatically reshape the landscape.<\/p>\n
In the Andean Plateau, although it was not the primary factor, tectonic activity was one of the mechanisms that allowed river capture to take place, but not by lifting the ground up. \u201cCounter to what most people think, the uplift needs to slow down,\u201d McQuarrie explains.<\/p>\n
As the ground was rising in response to tectonic activity\u2014a process known as uplifting\u2014and the plateau was forming, rivers didn\u2019t have enough power to erode through the rising ridgeline. However, once that tectonic uplift slowed, the erosional power of the river could carve through the ridgeline, ultimately breaching it and capturing a nearby river.<\/p>\n
In fact, according to the research team\u2019s models, tectonic uplift had to slow down by almost an order of magnitude before river capture could occur and reshape the area. \u201cWhen growth slows from 4 mm per year to 0.4 mm per year, that\u2019s when capture can occur, and you start getting a landscape that looks like the modern landscape.\u201d<\/p>\n
In a way, tectonic uplift and river incision were both drivers of the canyons\u2019 creation, McQuarrie says, \u201cBut the effect of tectonics wasn\u2019t the mountains going up and the rivers incising into them. It\u2019s that the mountains were up and then everything slowed down.\u201d Then rivers, strengthened by river capture, were able to carve the landscape that exists today.<\/p>\n
This research was supported by the National Science Foundation and the German Research Foundation.<\/p>\n
Source: University of Pittsburgh<\/a><\/p>\n","protected":false},"excerpt":{"rendered":"Share this Article You are free to share this article under the Attribution 4.0 International license. New research…\n","protected":false},"author":2,"featured_media":218507,"comment_status":"","ping_status":"","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[7],"tags":[61,60,24787,82],"class_list":{"0":"post-218506","1":"post","2":"type-post","3":"status-publish","4":"format-standard","5":"has-post-thumbnail","7":"category-science","8":"tag-ie","9":"tag-ireland","10":"tag-peru","11":"tag-science"},"_links":{"self":[{"href":"https:\/\/www.newsbeep.com\/ie\/wp-json\/wp\/v2\/posts\/218506","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.newsbeep.com\/ie\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.newsbeep.com\/ie\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/ie\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/ie\/wp-json\/wp\/v2\/comments?post=218506"}],"version-history":[{"count":0,"href":"https:\/\/www.newsbeep.com\/ie\/wp-json\/wp\/v2\/posts\/218506\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/ie\/wp-json\/wp\/v2\/media\/218507"}],"wp:attachment":[{"href":"https:\/\/www.newsbeep.com\/ie\/wp-json\/wp\/v2\/media?parent=218506"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.newsbeep.com\/ie\/wp-json\/wp\/v2\/categories?post=218506"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.newsbeep.com\/ie\/wp-json\/wp\/v2\/tags?post=218506"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}