Related: See all the best images of Earth from space A group of five barchan, or "horned," sand dunes can be seen in a zoomed-in version of the 2013 photo (see below). Over time, these arrowhead ...

Thanks to images in publications such as this and all across the internet, we know what to expect when we arrive at Great Sand Dunes National Park & Preserve. But imagine the early, unsuspecting ...