Ok but actually though that’s great! Why does sand have different textures in different areas? I assume it had to do with the elemental composition of the dirt, and geological shifts like some deserts being dry seabeds, but I don’t know the answers to a lot of these!
No, that's a funny conspiracy theory.
There really is no scientific definition of fish or tree. It's basically just calling something a square. Except "equilateral rectangle" is more of a definition than fish gets.
In a lot of places, it depends on two things especially: transport history and wave energy.
Sand grains get tumbled together during transport by rivers or waves, which breaks them into smaller pieces and smooths off the edges. So sand that's been carried a long distance, or which has been washing
around for a while, will be finer and smoother.
On beaches, the stronger the waves are the coarser material they can carry. So a beach that's exposed to the open ocean might be mostly gravel and cobbles, since all the finer-grained stuff gets washed away by the crashing surf.
A beach that's protected by a reef or sandbar or barrier island, which breaks up waves as they pass over and dissipates some of that energy, will be sandier, since the weaker waves can't carry it all off. And a lagoon behind the beach might even have very fine-grained mud!
Desert sand is a different animal. It's carried by wind rather than water, so it's all pretty fine-grained; even a howling gale can't carry gravel! Tumbling during wind transport also gives desert sand a microscopic "frosted glass" texture not seen in beach sand.
Fun fact: this texture makes desert sand unsuitable for use in concrete, since the cement doesn't stick to the frosted grains properly. For this reason, Saudi Arabia (a famously sandy country) actually imports a lot of sand
This is great. Instead of ridiculing the question it would be better to start explaining all the facets of sand and how it came to be in the Sahara and other deserts. And why there is (often) sand on the beach in the first place.
How *did* and come to be in the desert? I had literally never thought of that before. Is it because they used to be underwater?
But is it really sand at, say, a creek? What differentiates sand from dirt?
I have never thought about this, I'm not a geologist.
Short version,, all sand is erosion. Sometimes water,sometimes wind. Some beaches are mostly eroded lava. Some are mostly eroded coral. Some are mostly eroded stone. In deserts it's eroded stone as the topsoil has blown away so no longer retains moisture. The Sahara is only about 20% sand.
Plus: There were large lakes and rivers in and around today's Sahara desert. Sahara area was not always a desert. Fun fact: In the movie / book The English Patient a cave in the Sahara plays an important role with ancient cave paintings showing swimmers.
