In 1997, two Columbia University oceanographers and geophysicists (and again not archaeologists), Walter Pitman and Bill Ryan, presented a widely heralded theory that the breaching of a shallow ridge around 7200 years before the present, literally ‘opened the flood gates’ from the Mediterranean and ‘deluged’ the lower elevations of a landlocked basin to create the Black Sea. The two researchers also upped the scientific ante by suggesting that the event correlated in time, and was one and the same as the Biblical tale of Noah’s flood. The well-publicized theory received much attention, and given the institutional affiliations of the proponents, was broadly accepted as... gospel. In his important 2004 synthesis, The Long Summer: How Climate Changed Civilization, Brian Fagan captured the enthusiasm of the moment in vivid terms of prehistoric loss and angst:
The rising lake... killed carefully tended gardens... Helpless villages watched as their thatched houses and storage bins vanished under the brackish tide. At some points, the shoreline advanced up the river valleys as fast as a young man could walk. (p. 113).
Alternate Data and Interpretations
Though popular in the West, the thesis apparently was developed with little consultation or reference to over 30 years of archaeological, environmental, and geological research on the Black Sea by Russian scientists. At the forefront of this research tradition was the work of a Ukrainian climatologist, Valentina Yanko-Hombach, whose investigations (like parallel studies in the West), used thousands of sediment cores and high-resolution seismic profiles to study the geological and environmental history of the Black Sea. Aside from the radiocarbon evidence that local agriculture did not flourish for another thousand years (suggesting the lack of any farming communities that would have been available to be drowned), her work on ‘foraminifera’ (microscopic marine shells that varied by species depending on the water being fresh or saline) suggested instead that the Black Sea basin had experienced not one major deluge, but in fact a series of many smaller ‘floods’ over many thousands of years. Her sediment cores identified salt-tolerant foraminifera varieties around 9500 years ago, and concluded that if there was a deluge, ‘‘Noah’s flood legend has nothing to do with the Black Sea.’’
In 2002 the Journal of Marine Geology published a special volume of papers dedicated to presenting alternate data and interpretations of the Black Sea issue. One Canadian-led study indicated that the salinity of the Black Sea was never as low as that of a freshwater lake, and that gradual processes were sufficient to account for reported changes in the water chemistry of the Black Sea. In addition, pollen data suggest that environmental conditions were not amenable to either pastoral or agricultural settlements along the shores of the Back Sea until 4600 BP, or 3000 years later than the postulated flood.
The deluge hypothesis - and the international debate it precipitated - was promulgated long after the collapse of the Soviet Union and thus could not be attributed to political or Cold War barriers, only linguistic and cultural ones. What the debate does underscore is the critical need to evaluate different interpretations of cultural and environmental history with both a strong multidisciplinary and ‘crosscultural’ perspective. Sometimes in science it takes a small voice to muster the courage to say ‘‘the Emperor has no clothes’’ - hopefully in the same language as the audience.
Stopping the Flood: The Trigger of Gradual Sea-Level Rise
As recently highlighted this year for its significance by a National Academy of Science review, two scientists, an archaeologist and paleoclimatologist, Douglas Kennett and James Kennett presented a radical new interpretation of the role of Holocene climate change on the origins of civilization. Instead of prolonged droughts, they argue that a slow-down in the rate of marine transgression, or ‘sea-level rise’ - and the associated formation of high water tables, coastal estuaries, and marshes - may have played an even more critical role in the formation of city-states in Mesopotamian culture history.
They summarized available climatic data for the Persian Gulf region and concluded that climate change between 10 000 and 5000 BP, but not drought alone, was responsible for the prehistoric demographic shifts and cultural changes documented in the archaeological record. They argued that between 9000 and 8000 BP the region experienced a period of high humidity and frequent monsoons that resulted in dispersed lakes, the availability of rich aquatic resources. High rates of sea-level rise also created inshoreline incursion rates of 110 m (c. 330 feet) per year, a rate equal to the loss of six miles of shoreline per century. This rapid shoreline incursion would, they postulate, have led to dispersed settlements that needed to periodically move inland.
Then, after 8000 BP, the slowdown or demise of melting ice brought a slowdown in the rate of sea-level rise and marine encroachment. This change in turn led to the formation of stable wetlands and marsh habitats, which depend upon low rates of ‘marine transgression’ to maintain sediments deposition at pace with the rising waters. These ecological changes created important new subsistence sources including access to fresh water, a diverse set of new habitats for hunting and fishing of birds, fish, and land animals. This period also corresponded with the initial formulation, between 8000 and 6300 BP, of centralized settlements - the Ubaid Period - in southern Mesopotamia.
They also make the point, overlooked by others, that irrigation agriculture can only be practiced in areas of high water table and that canal systems could have ‘only been successfully constructed after’ the wetlands and high water tables had formed and stabilized. Unlike earlier theories stemming from the original 1981 suggestion by Dr. Adams, that the early Mesopotamia centers developed as a ‘result’ of irrigation agriculture, the authors reverse the case and argue instead that irrigation agriculture came about ‘after’ the city-state had formed and only after the water table had stabilized near the surface. After 6300 BP - the Uruk Period - they point to an expanding population, the advent of canal systems, and the realignment of settlement patterns. Instead of being oriented to the irregular topography and shorelines of the marshes and estuaries, these growing urban centers followed lineal patterns paralleling the extensive network of the new canal and irrigation systems. In essence, while increasing aridity may have added to the process after 6200 BP, they argue the primary impetus was due to ‘‘a deceleration in marine transgression that stimulated the expansion of floodplains in southern Mesopotamia and formation of high water table necessary for large-scale, flood plain irrigation agriculture.’’
Not only does this new model present a convincing alternative to attributing demographic, settlement and economic shifts in culture history to catastrophic causes, but they also suggest, as did others 2 years before, that the source of several myths of biblical floods derived more likely from the area of southern Mesopotamia, not the Black Sea. They also conclude that both the Sumerian and the Christian flood sagas (myths) more likely reflected a period of rapid sea-level rise forming a rapidly expanding inland sea several thousand years before the advent of the Mesopotamian Urban centers.
World History
