How Did the Ocean Become Salty?

The ocean became salty because tiny particles from rocks and soil got washed into it over a very long time.

Imagine you have a big bowl of water, like your bathtub. Now, suppose every day you throw in a little bit of salt, maybe from the snacks you eat or the salt you use for cooking. After many days, weeks, and even years, that tiny bit of salt adds up, and your bathwater becomes salty.

That’s kind of what happened with the ocean! Long ago, when Earth was still young, there was a lot more rock and soil on land. Rain would fall, and it would wash dirt and minerals, like salt, from those rocks into rivers and lakes. Then the rivers carried all that stuff down to the ocean.

Over millions of years, this happened again and again, rain washing away tiny bits of salt until the ocean got really salty, just like your bathtub if you kept adding salt every day!

Once the salt is in the ocean, it doesn’t just disappear. It stays there because water can evaporate, but the salt can't, it’s too heavy to go up with the steam. So when water from the ocean turns into clouds and falls back as rain or snow, the salt stays behind, making the ocean even saltier over time!