560 50 BC. b. Formation of hydrogen sulfide zone in the Black Sea as result of decomposition of the giant sapropel deposits: Huge volumes of dead plankton, together with organic matter from the land, were deposited on the seafloor. At the same time, the incoming saline water suffocated the basin with the poisonous gas hydrogen sulfide, which was liberated from the decaying organic matter (Dimitrov and Dimitrov, 2004). As a result the Black Sea waters below ~200 m have been anoxic for the past 7 160 radiocarbon yrs (Jones and Gagnon, 1994). c. Another approach of dating of the Black Sea Flood is by dating of the appearance of the first marine organisms after it. With the appearance of Mediterranean-type mollusk species such as Cardium exiguum and Mytilus galloprovincialis at ~7.5 ka cal. BP, dinoflagellates shifted to full euryhaline assemblages (Wall & Dale, 1974; Atanassova, 1995; Majora et.al., 2006). Marine species of mollusks (Ryan et al, 1997) and dinoflagellates (Wall & Dale, 1974) appear subsequently close to the onset of sapropel formation at 7 560 50 cal. yrs BP (Jones & Gagnon, 1994). d. The last approach of dating of the Black sea Flood is by dating of palynological records in sea cores. Cores that penetrated though the drape reveal a sharp basal contact between the overlying organic mud with its marine molluscs and an underlying sand of variable thickness, rich in Dreissena sp. detritus. Recent palynological and dinocyst analyses by Popescu et al.(s.p.) on samples from within these cores indicate an abrupt replacement of the Black Sea freshwater dinocysts by a Mediterranean population at 7150 Radiocarbon yrs BP 7550 cal BP = 5550 BC. e. Seismic surveys indicate the presence of well preserved drowned beaches, sand dunes, and soils supporting the interpretations that the Black Sea was rapidly filled with marine water from the Mediterranean during the mid-Holocene (Dimitrov & Dimitrov, 2004, Lericolais et al., 2007) 2.2.Catastrophic rainfall Shopov et al., (1996) recorded catastrophic rainfall at 5600-5500 years B.C. by rapid increasing of the growth rate of a Bulgarian speleothem in result of faster precipitation of the speleothem calcite produced by much greater rainfalls. Speleothem growth rate depend primary on feed water flow rate (Gonzalez et al. 1992, Shopov et al. 1994, Hill and Forti, 1997), which variations are determined by the rainfall. Higher rainfall dissolves more carbonate from the bedrock, which letter re-precipitates as more calcite on speleothem surface. The observed high linear correlation (r= +0.57) between the growth rate of the speleothems and the annual precipitation at the cave site ........ .. ..... .. ....... ..... 2012 .......... .......... .. ..... (Shopov et al., 1996, 1997) allows quantitative reconstruction of the precipitation by measurement of the speleothem growth rate variations (Stoykova et al., 2005). By dense C14 dating of a speleothem from Duhlata Cave, Bulgaria Shopov et al. (1996, 1997) found that during 5600-5500 cal. years B.C. its growth rate (averaged for 120 years) exceeds 53 times its recent value, suggesting that enormous precipitation flooded the Black Sea basin at that time. All C-14 dates of this speleothem were