Of the salts of the seas sodium chloride is by far the most abundant. The provenance of it is, however, a riddle. It was, and still is, assumed that the salts in the oceans originated mainly through importation from land, having been dissolved from rocks by flowing rivulets and rivers, themselves fed by underground sources, and the same process working on the rocks of the seabed. Terrestrial formations are rich in sodium, and in eons of time, it is assumed, the sodium washed out of the rocks supplied its content to the oceans; the seas evaporate and the concentration of these salts grows. But the rocks are by far not so rich in chlorine, and hence the problemâfrom where did chlorine come to contribute its abundance to oceanic water? There is chlorine in source water, but usually not in significant amounts. The proportion of salts in the rivers is very different from their proportion in the seas.
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Why should we be the only ones who have nice, salt-water oceans?