The source of salt in the ocean is from rocks on land. Carbon dioxide in rainwater corrodes rocks as it wends its way to the ocean, bringing with dissolved minerals. According to the United States Geological Survey, "The two ions that are present most often in seawater are chloride and sodium. These two make up over 90% of all dissolved ions in seawater."
In fact, if all the salt in the ocean were removed and spread evenly over the Earth's land surface, it would form a layer more than 500 feet (166 meters) thick—about the height of a 40-story office building
The article contains a number of other facts you can share with strangers on your next elevator ride:
- Oceans cover about 70% of the Earth's surface.
- Approximately 97% of all water on and in the Earth is saline, or saltwater.
- The concentration of salt in seawater (its salinity) is about 35 parts per thousand, meaning about 3.5% of the weight of seawater comes from the dissolved salts.
- In a cubic mile of seawater, the weight of the salt (as sodium chloride) would be about 120 million tons.
- A cubic mile of seawater can also contain up to 25 pounds of gold and up to 45 pounds of silver.
- 1 cubic mile contains 1,101,117,147,000 gallons of water.