Re: What was the color of the primordial soup ocean?

Rose:

You have asked a very good question. I will say right away that I don't
believe anyone knows the answer. However, we can make some educated guesses.

The primordial ocean probably differed from the modern ocean in a lot of
ways. It wasn't as salty. The salt in the ocean comes from minerals, and it
took some considerable amount of time for enough minerals to dissolve to
make the ocean as salty as it is today.

The modern ocean has a lot of floating organisms, many of which are large
enough to see, and many of which have white calcium-carbonate shells. None
of this would have existed in the primordial ocean.

The modern ocean contains, near the mouths of rivers, a fair amount of
suspended sediment. Four billion years ago the kinds of sediment reaching
the ocean would have been very different. Erosion was much faster, because
there were no plants to trap sediment. However, weathering was probably
slower, because plants and microorganisms cause a lot of weathering.
Therefore, most of the sediment reaching the sea would have been relatively
coarse, and it would have settled to the sea floor relatively quickly.

Of course, the sea would not have been polluted by people; there was no
floating tar (no tar at all; it comes, ultimately, from decaying
organisms), no bubbles of detergent, and no bits of plastic, paper, or wood.

I think that the primordial ocean was clearer than the modern ocean. If
there were places where the primitive organic molecules were concentrated,
such as in coastal lagoons, the water may have been cloudy, but not as
cloudy as it is today in similar places. Aside from greater clarity, the
color may not have been much different from what it is today in the open ocean.

David Kopaska-Merkel
Geological Survey of Alabama
PO Box 869999
Tuscaloosa AL 35486-6999
(205) 349-2852
FAX (205) 349-2861
www.gsa.state.al.us