#yardang

Wind, ice and sand

Wandering along the beaches of an icy Lake Michigan, the photographer spotted these foot high baby yardangs (aka hoodoos) on the normally sandy beach. Dozens of these towers were rising up over what had been a flat expanse of sand, and the life cycle of this phenomenon reveals in a few days or weeks erosional processes that take many millennia or more in rocks. The beach was frozen in the winter cold, solidifying. The ice (which is also a mineral) cemented the grains into a temporary, temperature mediated sandstone, in much the same way as calcite or silica from the waters that percolate the depths of the Earth do to sediments during their transformation into rock (a complex set of processes known as diagenesis). The howling winter winds then eroded the beach in the same way that they would a sandstone, but much faster than usual since ice is a lot softer than the usual mineral cements found in sedimentary rocks.

A couple of days later (these were taken on Valentine's day), he returned to check on them, but a rise in temperature had dissolved them all, melting their icy cement.

Geological processes are fractalic as I keep on emphasising, recurring across scales from the tiny to the huge (see http://on.fb.me/1L72vp3). Yardangs many tens of metres tall exist, as do these beautiful tiddlers. This process reveals another fractalic dimension, that of motion through time. The same processes took place over a couple of days, rather than the usual millions of years.

Loz

Amazing wind

These wind-erosion features in Egypt's White Desert are some of the most amazing erosional features on Earth.

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 out of the water, making it so that erosion could take hold. 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, as water is a much more powerful erosive agent. Water started eroding through the layers, breaking through the more resistant upper layers in places. 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, yardangs, or ventifacts.

-JBB

Image credit: https://flic.kr/p/e3ae5g

Original caption:

During our two months travelling in South America, we came across to some breathtaking weather conditions. This is a Timelapse collection of the most stunning storms and clouds around Atacama desert in Chile, Lake Titicaca and Uyuni in Bolivia.

Music license by epidemicsound.com

Bolivia and Peru traveling with really neat editing. Original caption:

“Feb 2018 Salar de Uyuni, Cementerio de trenes, Iglesia San Cristobal Lipez, Géiseres, Laguna Colorada y Flamencos, Arbol de Piedra, Isla de la Luna, Teleférico La Paz, Puno Islas flotantes y Ciudad del Cusco

Photo Gallery https://adrianrivera.myportfolio.com/

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