If water flowing over continents in rivers is what concentrates salt in our ocean, would a planet that has always been covered in water just be freshwater? The water is just sitting there, not eroding through salts.
If water flowing over continents in rivers is what concentrates salt in our ocean, would a planet that has always been covered in water just be freshwater? The water is just sitting there, not eroding through salts.
So let’s consider the premise that our oceans got their salt from water washing over the land in rivers after it rains.
On a world completely covered with water, are we presuming there is a solid ocean bottom? Because if so, that water is “washing over the land” 24/7, isn’t it?
Running water causes a lot more erosion than stationary bodies of water. Consider lakes, which are still cycling water much like a river, but over thousands of years they deposit so much silt that they cease to exist.
Underwater erosion is certainly a thing, but in comparison to downhill water erosion on land, it’s pretty insignificant. It does not seem a given that it could significantly offset the processes that remove salt from salt water.
A river will erode more than a static lake, true, but what about an ocean? They’re far from calm. And an ocean’s amount of water to rock contact is a couple of orders of magnitude greater than a rocky landscape with rivers in specific places, so more sites where salination can occur.