A fact for Sunday

Some time ago, I learned that in the beginning seawater was not salty, rather that it was much the same as the fresh water with which it was fed.

Then I learned that the fresh water was not that fresh, it was carrying the chemical products of erosion into the sea. This was a cumulative process, as these chemical products were left behind when seawater evaporated up into the sky, on its way back to the rivers. The sea is steadily getting more and more salty.

The same sort of thing can happen in hydraulic basins in the interior of continents, where the rainwater does not make it to the sea proper. Hence the salt flats of Salt Lake City.

Next I wondered about the salt, sodium chloride, perhaps not an ingredient of rock.

Then, yesterday, I turned up references 1, 2 and 3. Where the answer seems to be that while the sodium comes, in the first instance, from the erosion of primary rocks, the chlorine comes from volcanoes under the sea. The sodium and chlorine coexist as ions in the sea, coming together as salt when the seawater evaporates.

Something of the sort can also happen underneath lakes - giving rise to the striking images at reference 3, of which a sample is included above.

On which, I can let the matter rest.

Reference 1: https://www.thoughtco.com/all-about-salt-1441186.

Reference 2: https://www.futurelearn.com/courses/exploring-our-ocean/0/steps/730.

Reference 3: https://www.swisseduc.ch/stromboli/perm/erta/dallol-2011-en.html.