Amazing windThese are some of the craziest wind-erosion pillars I’ve ever seen. These pillars
Amazing windThese are some of the craziest wind-erosion pillars I’ve ever seen. These pillars are formed by a sequence of water erosion followed by wind erosion. To form these, first the sedimentary layers had to be deposited and lithified by some sort of cement. Those rocks then were uplifted, either geologically or due to a drop in local water levels. Water started eroding through the layers, breaking through the more resistant upper layers in places. There had to be a role for water in creating channels or some other topography that penetrated the top layer, allowing wind to get through.At some point, wind took over. Wind erodes by picking up sand grains and sandblasting anything it runs into. Sand grains move via saltation, they bounce along the ground and usually don’t get more than a meter or so off the ground. Sand erosion therefore eats away at any rocks that are about a meter or less above the ground, leaving the slender pillars that hold up the larger rocks in this part of Egypt’s White Desert.Other terms for these could include mushrooms or ventifacts.-JBBImage credit: https://flic.kr/p/e3ae5gRead more:http://hte.si.edu/erosionmore.htmlhttp://bit.ly/1xuAobD -- source link
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