Why is there sand in deserts and no dirt? Why isn’t there sand anywhere else?

Question

I figured it was something to do with sand being light enough to be carried by wind, but that wouldn’t explain why the rest of the world lacks sand.

In: 327

Answer 1

Sand is defined by particle size (0.005 – 2 mm). Smaller particles are called silt, bigger ones are called gravel. What you would consider dirt is made up of particles of various sizes, including sand particles. So in fact, you will have sand in the ground almost anywhere on earth.

And while we’re on it: Deserts are defined by lack of moisture. Not presence of sand, not temperature.

So: There absolutely can be sand without it being a desert, and there absolutely are deserts without sand.

Why are deserts where they are?
Without going too in-depth, deserts emerge where there is more evaporation than precipitation, resulting in (relatively) permanent aridity. This can have various causes, and we actually differentiate deserts by their origin.

Why is there no dirt in, say, the Sahara desert?
Let’s actually call it soil. Soil is made up of mineral and organic particles. You might be able to guess where I’m going here – there is not much vegetation or life in a desert. Hence very little organic particles and no soil.