Why star dunes are rarely recognised in the rock record

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.

Been there, read carefully the entire paper --- couple of minor editorial mistakes and a doubt i express nelow, only. Nice study.

Fascinating to think what could have happened in Africa at the beginning of the Holocene: wildfire ravaging NW Africa and the West Africant Monsoon retreating to the South?

Maybe this is assumed if you know anything about dune science, but: exactly what is the ground penetrating radar measuring? Are these layers of different density/compaction of sand? How do they form?

Either way, I didn't know dunes could have that much detectable internal structure (though in retrospect I should have). Based on playing on beach dunes, I tend to think of dry dune sand as just a step above liquid.

Smithsonian magazine had an article on this finding some days ago

https://www.smithsonianmag.com/smart-news/scientists-unravel...

If the dunes move, the sand remixes, and then, how can the strata be meaningfully explored?

TIL: OSL