Jan 2, 2018
Sand and Ice. The Great Dunes as tall as mountains! Sand and sediment from the Sangre De Cristo mountain range dumped into the valley over geological time periods and then with the receding of lakes, the sand was exposed. And with the South West winds - Dunes were formed. #thegreatsanddunes #coloradosanddunes #permafrost #ripirianforest #ancientwatersheddeposit @sayerdan4th (at Great Sand Dunes National Park and Preserve)