Sand is so confusing. I go to one beach and it’s soft sand I go five minutes down the road and is angry sand full of broken shells and hurts my feet, I go to the other side of the country and it’s made of rocks and no sand. I look at photos of the Sahara desert and there is lots of sand and no sea! How does the sand decide where to go?
Also if I brought my digger to the beach and made a big hole would there be dirt under the sand?
In: Planetary Science
It all depends on when the sand was made; ocean currents; costal topography
Believe it or not; not every piece of coast is the same age; expierences the same wave intensity/frequency and ocean live.
The soft sand was probably placed there to form a nice beach if it’s only in one section and everything else is shelly.
Think of sand as a size range of granular materials. It can be small pieces of rock or shells, hence seeing different types.
Wave action will break down rock to sand over time. So if you’re on a rocky beach, it’s probably relatively new. Additionally, the waves and currents may also be moving the sand to another location so you won’t see much of it.
Wind can also move sand, although it tends to be in much smaller pieces since the wind doesn’t have as much energy as a wave does. You can also tell how much sand has moved based on how angular or rounded it is. Sand that has moved a long way will be rounded where it’s been moved over and around other materials. An angular sand will be closer to its original location. Where it goes is like anything else, it relies on energy moving it. It goes where the wind or wave takes it. You can learn the currents and patterns to get an idea of where it should be going, but it’s kind of a weird science and you never have all the data you really need.
There’s no one thing underlying all beaches, but you won’t hit dirt. You may hit mud or seashells, you’ll eventually hit rock. The depth varies depending on the location.
The reason sand exists, and is particularly common near oceans and lakes, is because the motion of the water running over rocks breaks off tiny pieces of the rocks and then deposits it on the beach. So the type of sand depends on where it’s coming from and what types of rocks are being deposited there.
As far as the shells, that’s also related to currents. There are certain areas in an ocean that have more dense aquatic life like shells and they tend to get deposited in certain places due to the currents.
If you dug under the sand deep enough, you would eventually find soil that isn’t sand but you’d have to go really really deep. That sand has been getting deposited there for millions of years.
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