суббота, 23 сентября 2017 г.

Slot Canyons These fantastical landforms are the result of…

Slot Canyons These fantastical landforms are the result of…


Slot Canyons


These fantastical landforms are the result of flash flooding, usually in arid areas. Water gushes through the weak points in the rock when the occasional downpours happen, gradually eroding these deep narrow canyons. They can be as narrow as a metre for a 30 m depth. One of the most famous on Earth is the Siq (see http://bit.ly/2uIfSxL), that leads to the ancient Nabatean city of Petra in Jordan. They are usually carved into sedimentary rocks, especially sandstone.



Beauty, in this case, is also the handmaiden of peril, since their method of formation implies that a flash flood can gush through suddenly, so some basic precautions should be taken. Never camp in one, and if you are planning a hike in a non guided example, it’s wise to check the weather upstream to check if any rain or storms have recently occurred or are likely during your trip. Being trapped by one would not be a good idea, as the next exit may well be too far away to escape and the speed of flash flood water makes survival chances slim.


This photo comes from Antelope Canyon, where the Navajo sandstone (see http://bit.ly/1seOVqR) has been eroded into wild shapes by rushing sand laden water, funnelled from the upstream basin. It can only be visited on guided tours, but 11 tourists were still killed there in 1997 by a flash flood from a storm 10 km upstream.


Loz


Image credit: Lucas Löffler


http://www.americansouthwest.net/slot_canyons/index.html


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