Black Sea Floods

At www.sciencenews.org/view/generic/id/71291/title/Cave_formations_record_B… … stalagmites in a cave in Turkey not far away from the Black Sea coastline contain a record of 19 flooding events – 0ver 650,000 years. It seems over the course of time a series of floods have drowned the Black Sea and its environs – over and over again (see Nature Geoscience March 13th). In other words, the waters of the Mediterranean seem to have poured into the Black Sea on some 12 occasions and the waters of the Caspian did the same thing on the other 7 occasions. Why?