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Salts in the Earth's early ocean
We all know that today ocean waters are very salty. There aren't many sedimentary rocks
older than 2.5 billion years (see geologic time
) that means that there must have been mostly igneous rocks
at the beginning of time. Since igneous rocks are made of mostly of iron and aluminum, those were the only rocks around, and these rocks are easily destroyed by acids
, that means that the waste products of erosion by acid
, namely chlorine and iron from the rocks and the acid, had no where to go but into the ocean. Thus the early ocean was full of chrorine and iron.
What caused this environment to change was the introduction of oxygen into the system by the activity of early life. Free oxygen is an agent of change, ready to attack other molecules and react with them. In the early ocean environment, oxygen from life attacked iron left over from erosion.
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