I remember when I was quite young, I asked the question, “Why is the ocean salty?” We had just visited my grandparents in Florida and I had discovered first hand just how salty the seawater in the Gulf of Mexico could be. I was told that salt dissolves in water and is carried to the oceans by rivers, so that over time the sea keeps getting saltier. It seemed like a good answer to me, so I moved on other questions.
Recently, however, I heard Robert Ballard, the famous oceanographer and underwater archaeologist of Titanic and Thresher fame, say that, until recently, oceanographers did not know why the ocean was salty. They didn’t know until 1979 to be exact. The problem is that the old explanation, that salt was carried in from the rivers, didn’t quite work. The chemistry of the oceans and the chemistry of the rivers were different enough to suggest that something else was going on. Here is Ballard explaining their discovery on National Geographic.
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