NEWS re Black Sea Flood

[Dr. John E. McLaughlin]

[ moderator re-formatted ]

Steve Long wrote:

> I quoted:
> << The incoming salt water, more dense than the fresh water it
> displaced, plunged to the bottom of the lake bed, transforming it
> into a sea where the depths support no life.>>

> It's a valid point.  I don't know what the scientists involved would say, but
> my guess is that they would say it's a matter of degree.

> Salinity is the relative concentration of ions dissolved in the water.
> Salinity in lakes is not only increased by lack of outflow, but also by the
> chemical composition of the inflow and the geology it passes through.  And
> another factor is the amount of climatic evaporation.  The Great Salt Lake is
> an example of especially high salinity due to the chemical makeup of the
> surrounding area - which includes the famous Bonneville Salt flats.  The
> Caspian Sea is an example of a closed lake or inland sea where the evidence
> is of a large reduction in water level even in historical times.  You'll see
> the climatic factor sometimes phrased as "salt lakes only occur in arid
> regions."

> The Black Sea is fed by rivers that don't flow through regions of high
> aridity, evaporation or especially concentrated salineous chemical deposits.
> So at least the inflow would tend to be less preconcentrating than those of
> heavily saline lakes like the Great Salt Lake or the Dead Sea.  Climatic
> evaporation would also seem to have been less of a factor, especially in the
> north.  So the relative salinity of the Black Sea 'before the flood' might
> still be conjectured to have been less than ocean-high levels of the entering
> Mediterranean.

A note on relative salinity for the non-fluid dynamics people.  Water of
different salinities does not mix very well in any condition except over
long periods of time and exceptionally high current or wave activity.  The
Great Salt Lake is an example of this.  The lake is only several dozen feet
deep at its deepest point, but there are actually two lakes, one on top of
the other.  The lake we see is composed of a solution that varies from 10 to
30% salinity depending on the evaporation/precipitation ratio over the last
few years (we're in a higher precipitation cycle right now, so the lake is
rising and salinity is dropping--we in the Great Basin benefit from global
warming).  This lake is about two dozen feet deep.

The other lake lies beneath the other one and is composed of a heavy brine
solution that approaches 40-50% salinity (I'm remembering right now, so the
numbers may be off a little, but the relative salinity is right) and never
varies by precipitation cycle.  In fact, if this lower lake were ever
exposed to the air for any length of time, there would be a massive
explosion of dissolved hydrogen sulfide that would wipe out all life in the
Valley (about 2 million persons) like the volcanic CO2 gas cloud did in
Cameroon a couple decades ago.

These two layers don't mix.  They are virtually independent of one another.
One of the chemical companies around the lake (a major producer of magnesium
chloride, potassium sulfate, and road salt), actually uses this to their
advantage.  Their major brine collection ponds are about 30 miles away from
the main plant.  Instead of pumping the brine through pipes or running it
through surface canals, they have scoured an open trench on the lake bed.
The heavier brine from their first pond sinks into the trench and flows by
gravity along it until it reaches the plant site where it is pumped into
surface ponds.  Their loss through mixing with the upper lake water is only
about 1%.

What does this have to do with the Black Sea?  Well, 1) it demonstrates how
different salinity layers don't mix well in lakes, 2) heavier salinity water
sinks.  If the Black Sea had developed as a freshwater lake and was later
inundated by Mediterranean salt water, then the heavier sea water would have
settled to the bottom.  If, however, the Black Sea was a body of water with
greater salinity, then the influx of Mediterranean water would have floated
on top and not mixed with the higher salinity layer.  The layers of the
Great Salt Lake, however, developed different salinity layers without a
major influx of new water.  The lake naturally developed layers.  Could this
layered salinity have also happened in the Black Sea without postulating
radical influxes of new water?  Probably.  The sea invasion theory may or
may not be correct, but there are other natural explanations for different
salinity layers in inland bodies of saline water.

John E. McLaughlin, Ph.D.
Assistant Professor
mclasutt at brigham.net

Program Director
Utah State University On-Line Linguistics
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