Where did all the sand in the Sahara desert come from?
All scholars hold the view that the primary source of the world’s quartz sand and sandstone deposits is granite rock – that is to say billions of years of weathering and erosion of granite outcrops created the sand that forms our beaches, sandy deserts and sandstone deposits globally.
Impossible!
No amount of time or erosion by rainwater could ever produce such vast quantities of pure quartz grains let alone dump them in one basic location to remain virtually unaltered for many millions of years. It doesn’t add up, especially when considering how granitic source rock rarely protrudes earth’s surface.
The vast sandy oceans comprising the Sahara look pristine, as though they were laid down fairly recently. That’s because they were!
Extraterrestrial Sands 
The theory states that the planet Mars entered into hundreds of catastrophic close encounters with earth during historical times. During these encounters an incandescent molten Mars internally convulsed and ejected immeasurable quantities of vaporised rock, volatiles, dust and debris out into space – a natural by-product of planetary chaos. Vast swaths of rock vapour fell to earth (along with tons of other sedimentary material) where it condensed out of the atmosphere as tiny quartz grains. In other words, it rained sand!
Lots of it!
As the sand fell it ‘choked’ what was previously a verdant green paradise.
From lakes and grasslands with hippos and giraffes to a vast desert, North Africa’s sudden geographical transformation 5,000 years ago was one of the planet’s most dramatic climate shifts. The transformation took place nearly simultaneously across the continent’s northern half …
https://www.livescience.com/28493-when-sahara-desert-formed.html
The reason why sand is relatively uniform in size is because, like rain, it fell from the sky!
As the sand grains fell they were coated in a submicroscopic coating of iron rich clay drawn from moisture in earth’s atmosphere – this is where sand gets its colour. Any variations would be down to density and saturation variations in the atmosphere. Post depositional processes would of course play a part, but quartz sand has nothing to do with the absurd “billions of years of erosion” from granitic rock.
If sand is the result of millions of years of fluvial erosion (rainwater, stream flow, etc.) then how did it maintain its iron rich coatings? Moreover, if sand was initially born from granite as clear quartz crystals how on earth did the the gains become coated in the first place? For more detailed answers I refer you to my latest book … “Extraterrestrial Sands.”
There were numerous ET sand episodes around the globe. Many clouds falling in regions that, as with the Sahara, were once green and fertile such as the Rubʿ al-Khali, in Arabia.
Another such deposit would be the Thar Desert in India.
And the coastal Namib desert in southern Africa.
All fell from the sky!
Next time you dig out your bucket and spade and feel like making sandcastles on the beach have a thought for the origin of the tiny fragments of rock you are using for construction … sand from Mars. As too are large boulders, rocks, stones, pebbles, water, volatiles, dust and debris – material believed to be indigenous to earth, is largely from the planet that was once our home … Mars.
