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.
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I live on an island. It’s basically all sand under the grass. Any time they do construction you can see it. And we have ants like you wouldn’t believe. It’s like a giant anthill. I’m assuming this is because I live right between the ocean and the bay.
Most deserts are not sand they are ice. It is the amount of precipitation during a year that defines a desert not surface material or temperature. The largest desert in the world is Antarctica.
Even if you look at warm deserts the large is Sahara but only 20% is sand. Most of it is stone plateaus. The sand and dirt have in large part been blown away.
The response is sand is dirt is mineral-like sand and organic part from plants. The organic part will get dried up and when the sane drift gets crushed to dust, new sand is produced all the time from rocks that get eroded by the wind, moving sand, etc.
Desert sand is not like the typical sand you find on the beach. On a beach, it is relatively large and not to rounded pieces of rock. Desert sand is a lot finer and has smooth edges. You can for example not use typical desert sand when you make concrete, countries like Saudi Arabia and other desert counties import huge amounts of sand for construction.
Part of your trouble is based on your mental picture of a desert being a little off. Deserts are way more complex and varied than you think (like, some are permanently icy cold!) The main feature is that it hardly rains at all.
Hot sandy deserts are sandy because there are fewer plants to live and die there, probably because it’s so hot and windy and barely rains so nothing can live. (But if you study deserts, you will find there’s actually a ton of life, just not the kinds you typically think of.)
This type of desert seems to you like they have no dirt because there isn’t enough decayed materials mixed in for you to say “that’s dirt.”
Dirt has enough rotten plant material in there for you to say “that’s not sand.” But dirt has teeny rocks in it. And that’s sand.
In places with dirt, there’s more life going on.
At the beach, the moving water makes it hard for lots of plants to live and die, and it keeps moving it all around. So we have sand there too instead of dirt.
Some moving water instead has mud (wet dirt) because living things ARE dying over many years there. If nothing died anywhere near a river for a long time, it would slowly get to be more sandy and less muddy.
That’s it really. If you removed all the life and rot from the planet, and crushed the whole planet up small, it would all be sand.
Soil is generally made up of a combination of sand, silt, clay, and organic matter in varying amounts. The top soil in most parts of the world that have some vegetation is most likely what you think of as “dirt”. In reality, it is just a mixture of those basic soil elements with a bit more organic matter from broken down and decaying plant matter. The gritty bits in the dirt, that’s sand. Goopy, muddy bits, probably clays and silts. If you were to boil all of the water out of the soil you could pass it through a series of sieves with increasingly smaller mesh sizes and see the different components and their proportions. Rocks being the largest particle, through sand, to clay being the smallest grain size.
Generally, under the topsoil, one type of soil component dominates with a bit of the others. This is where you might hear things like a “sandy soil” or a “clayey soil”. The different proportions of each component gives you different soil properties. Clayey soils are “tight” and don’t let water infiltrate well, for instance. Water wells would be in sandy soils where ground water can flow relatively freely to replenish the water in the well. Different areas have different soils left behind from geological formations and glaciers. Eventually, you can go deep enough and you’ll hit bedrock.
The desert, as you’re most likely thinking of it with big sand dunes, is simply an area that is predominantly sand with virtually no top soil. Loss of plant life and drought can functionally turn anywhere into a desert like what happened in the dust bowl.
Michigan has sand, lots and lots of sand, the last ice age crushed and ground rocks into sand.
We have sand dunes (Sleeping Bear Dunes National Lakeshore), Northern Michigan and the UP are very sandy.
Your view of what constitutes “desert” is not complete. In the geographic sense, “desert”simply denotes an exceedingly dry, or arid, region. It’s not concerned with the composition of the surface layer. There are mountainous deserts, salt flat deserts and ice sheet deserts, for example. Believe it or not the polar regions can be considered deserts.
In the upper Midwest if you dig a hole a few feet deep you will encounter sod, topsoil, and then sand as you go deeper.
My friend, you’ll be ecstatic to learn about beaches.
In all seriousness though, much of the time dirt isn’t just rock, but plant material and stuff mixed with it. Sand frequently is found in places where plants are less common and is mostly just rock
Deserts refer to the amount of rainfall not the soil type. Other people have answered why some deserts have sand.
Antarctica is a desert but has dirt under the snow and ice.
The entire premise of your question is wrong. Deserts have all types of soil in them. Have you ever seen a playa? That is clay and silt. Also, sand is found in many places. The topsoil of the upper Midwest of the US is mostly sand. River beds are made of sand.
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