Estimates of "absolute" sea level are important (though it's
partly a matter of whose figures you believe -- the main point on which most
specialists agree is that there was a catastrophic rise ca. 7600 BC), but there
are other factors that have to be considered. The sheer mass of the increased
Black Sea and the Caspian would have caused their beds to depress, but the
surrounding areas would have experienced compensatory uplift. This means that
the present elevation of potential spillways (very close to sea level) is
now probably higher than at the time of the Euxine Event (in addition to the
Don-Volga route there's another viable "floodway" along the Rostov-Makhachkala
line, just N of the Caucasus. The dynamics of such processes is very complex,
and our "armchair palaeohydrology" is of course speculative in the extreme.
However, the region in question is attracting more and more scholarly attention
and there should be no shortage of expert opinions in the near future. I think,
by the way, that it was the replenished Black Sea that overflowed into the
Caspian, not the other way over.
Piotr
Mark wrote:
There are some problems with this. Worldwide sea level at the
time of the Black Sea event was about 50 feet below present. The former outflow
of the Caspian to the Euxine Lake, presumably the route of the present Don-Volga
Canal, is above present sea level. I don't know what elevation this part of
Russia is. Volgograd (former Stalingrad), of course, is practically at sea
level, with the course of the Volga being below sea level after Volgograd. The
Caspian would have had to have been much higher than present, to overtop the
present barriers and flow to the Euxine.
I might add that this part of the world is quite geologically
active, experiencing uplift. The weight of the additional waters flowing into
the Black Sea would have caused some depression of the
seabed.