Paleo-dunes reminds me of when I was gobsmacked when I learned the kilometers deep sandstone deposits in Grand Canyon and Grand Staircase (Coconino and Navajo other sandstone formations) were sand from huge sediment carried by ancient east to west running possibly Mississippi sized rivers from the Himalaya high great Appalachian mountain ranges on the North American east coast. Huge mountains were just "sanded down" over time and deposited thousands of miles away to the west.

The surprised and shocked to learn that thousands(!!) of feet of rock had been eroded away above the current ground level of the Grand Canyon to move that enormous volume of former solid rock elsewhere. It boggles the mind to imagine a mile of rock over a large region just being just moved to a new location.

And then surprise turns to astonishment, as they say, to learn that the Vishnu Schist unconformity at the bottom of the whole sequence records several hundred million years in two periods of the earth being a giant snowball covered in ice where the entire continental surface across the planet was sanded almost smooth by enormous Greenland scale glaciers.

Geology is crazy.