Persian Gulf Once Dry, Green, and Inhabited by Humans: Implications

In the 1970s and 1980s, the late Saddam Hussein led the effort to nationalize the Western-owned Iraq Petroleum Company, seized control of the country in 1979, destroyed the water environments of Lower Mesopotamia, and sharply curtailed promising western-funded geologic, geographic, and archeological research. This research had demonstrated that about 14,000 B.C. the entire present Persian Gulf was a dry valley through which coursed both the Euphrates and Tigris Rivers, which emptied directly into the Gulf of Oman. The Gulf is very shallow in topography. Its maximum depth today is 270 feet and its average depth is around 150 feet.

Persian Gulf at 12,000 years B.C. “Figure 3: Reconstruction of the palaeoshorelines and palaeobathymetry for the Persian Gulf at 12,000 years ago. The lower part of the Gulf is first flooded at about 13,000 years BP but large freshwater lakes could have developed in several locations within the valley floor. Large shallow depressions also occur on the southern margin of the present Gulf.” Source: http://wwwrses.anu.edu.au/geodynamics/AnnRep/95/AR-Geod95.html and http://wwwrses.anu.edu.au/geodynamics/AnnRep/95/AR-Geod953.gif; accessed May 7, 2007.

Moreover, the research that was interrupted by the wars in Iraq, beginning with those perpetrated by Hussein, strongly suggest that prehistoric settlements of Stone Age humans “must” have been situated either on the floor of today’s Persian Gulf or beneath the present Mesopotamian alluvial plain (or both places), according to German researcher Werner Nutzel. (1) Further studies of the ancient climate and changes in the amount of water in the Mesopotamian river system and in the Gulf await peace in the region.

I. Science Behind Ancient Mesopotamia and Persian Gulf Paleoclimate

The German oceanographic research vessel Meteor during a voyage in the winter of 1964-1965 drilled deep core samples from the floor of the Persian Gulf. Tests of the retrieved floor sediments, especially the discovery of the respective proportions of organic materials, revealed “astonishing changes in its composition”, notes Near Eastern archeologist Hans J. Nissen. (2,3) With the help of individual carbon 14 measurements, it was possible to correlate dates of deposition with composition of the core samples.

Nissen explains: “Because the percentage of inorganic materials increases with the quantity of water flowing in from a river, a lower portion of organic material in the substances carried by a river and later deposited points to a large amount of water—that is, to high preciptiation in the drainage area of the river, and therefore to a damp, humid climate…The [findings] show that roughly in the middle of the fourth millennium B.C. [around 3,500 B.C.], what was probably a slight, but noticeable, change of climate must have taken place, leading to slightly cooler and dryer average conditions…[T]he sea level [of the Gulf] was almost three meters [10 feet] higher at the time the climatic changes began than it is today.” (2)

This ingenious methodology was used to date the sediments in the core samples to reconstruct the paleoclimate and archeology of the period 70,000 B.C. to the present.  

II. Time Line: Changes of the Mesopotamian River System: 70,000 B.C. to Today

Nutzel, applying the data from the Meteor core samples, theorizes (he calls it “theoretical geomorphology”) that four river systems--1a, 1b, 2 and 3--totally different from one another, existed in the period 70,000 B.C. until today. He then surmised archeological conditions for each period.

CLICK ON THE IMAGE TO ENLARGE Adaptation by M. O’Leary of Werner Nutzel map available in: “On the Geographical Position of as Yet Unexplored Early Mesopotamian Cultures: Contribution to the Theoretical Archaeology”, published in Journal of the American Oriental Society, Volume 99, Number 2, April-June, 1979, pp. 290.

River System 1: From about 70,000 B.C. until 5,500 B.C., there were two variations of an “incised river system”. The first system lasted from 70,000 B.C. (beginning of the last ice age) until 14,000 B.C. (maximum of the frigid ice age) and the second system lasted from 14,000 B.C. until the beginning of the “Atlanticum” (a warm and wet period of the Holocene geological epoch that extends back 11,430 +/- 130 years) about 5,500 B.C. The Atlanticum lasted from 5,500 B.C. until around 2,500 B.C.

River System 1a: Around 70,000 B.C., Mesopotamia and the Gulf area were warm, even warmer than today. More ice melted from the glacier zones in Anatolia (source of the Tigris and Euphrates rivers) and, as a result, the sea level was some 20-25 feet higher than today’s level. (4) The Persian Gulf must have covered much of what is today the Mesopotamia plain (Baghdad to the Gulf was submerged). After 70,000 B.C., the last ice age began. Temperatures fell, glaciers reformed in the higher altitudes in Anatolia, and the sea level began to drop, which included the Persian Gulf. The lowering of the sea level caused more and more land to emerge in the Mesopotamian plain.

Rivers on the plain, “seeing” a higher downslope gradient, began to incise deeper and deeper into their beds, thus creating river valleys. (4) By around 14,000 B.C., the rivers were maximally incised into their river valleys both in the Southern Mesopotamian plain and in the Gulf area, whose sea level had fallen some 120 meters (360 feet!). Thus, around 14,000 B.C., the Persian Gulf became a dry valley. “The original Euphrates and Tigris rivers emptied directly into the Gulf of Oman. In what is today’s Gulf several lakes mush have been formed. These lakes were ‘flow-through-lakes of the original river.” (4)

The coastlines of the rivers and lakes provided possible areas for settlement for humans, particularly for nomadic groups, which would have encountered good fishing and hunting. Limited amounts of vegetation could have been grown along side the rivers in both the Mesopotamian region and along the whole Gulf axis, according to Nutzel. 

River System 1b: The maximum cold was reached at 14,000 B.C., and then began the onset of the “Atlanticum”, the warm and wet subdivision of the Holocene epoch. The glaciers melted and the Gulf sea level ascended again. (Elsewhere, England once again became an island and northern Europe became very marshy.) Coastal settlements that earlier had been above sea level were drowned during the Atlanticum. The Gulf began to fill up with water, extending onto the continent once again in Southern Mesopotamia. (There were periodical “stops of transgression” in which the postglacial melting was interrupted. For example, in the 9th millennium B.C., the ocean “again released land for several centuries during the “Dryastime”.) (5) The course of the drowned rivers in the Gulf has been accurately located, according to Nutzel, although the courses of the ancient Euphrates and the Tigris rivers beneath the large amount of alluvium covering Lower Mesopotamia have not.

From the archeology perspective, extraordinary river flow evolved to flooding problems for settlers during the summer months from 14,000 B.C. to 5,500 B.C. If nomads retreated during the flooding into the Zagros Mountains in what is today Iran, they would have been safe, enjoying good hunting and fishing and vegetation cultivation along the widedn places of the “incised river system” especially in the alluvium that was beginning to accumulate in Lower Mesopotamia.

River System 2: Around 5,500 B.C., the sea level was still about 50 feet lower than it is today. The original river systems must therefore still have been “incised” into the Mesopotamia plain, says Nutzel. In the 4th millennium B.C. (4,000 B.C. to 3,000 B.C.), however, the rivers began to “braid” for two reasons. In 5,500 B.C., the sea level began to rise again, reaching about to the present level at around 4,000 B.C., and then kept rising, reaching in 3,000 B.C. about 10 feet above what it is today, filling up the river valleys in  Southern Mesopotamia and then braiding out.

When the Euphrates and the Tigris rivers met the rising sea level at the Gulf head waters, they slowed down, causing the braiding and deposition of sediment (from the highlands in Anatolia) in the delta. The deposition of sediment raised the level of the middle of the Mesopotamia plain and eventually caused the two rivers to slide one to either side of the fertile hump formed along the axis of the valley, according to Nutzel. The flow in the rivers rose in response to the increased rainfall that characterized the humid and wet Atlanticum. Recall that the core samples drilled by the Meteor research ship provided the data on organic and inorganic content, which enbabled researchers to determine the paleoclimate.

Settlement around 3,500 B.C. was everywhere possible on the plains around the river system. South of the ancient city of Ur, however, there were no places for settlement because of the rising sea level and encroaching water in the Gulf. The danger of flooding was high, however, so humans chose higher places on which to dwell, such as wind-shaped hills and the mountain ranges parallel to the Zagros mountain chains, which today are drowned, according to Nutzel. Irrigation of fertile soil was easy with so much water available.

River System 3: Around 3,000 B.C. the sea level again began to fall until it reached its present level. A braided river system continued to exist at the time, which created unparalleled opportunities for irrigation systems to water the crops as managed by the human groups dwelling there in a temperate climate.

III. Implications of Findings: Theories
Several theories have been advanced by researchers on the meaning of the data and information presented above. The first theories, developed by a group of researchers at The Australian National University in 1995, concern the enigmatic origins of the Sumerians: “The region at the northern end of the present Gulf and at the junction of the Euphrates and Tigris Rivers was settled by the early Sumerians during the fourth millennium BC but the origin of this civilization has raised many questions. Whatever directions the search for answers may take, a significant element in the puzzle must be the evolution of the physical environment of the Gulf itself. For example, during Palaeolithic (before about 8000 years B.C.) and Mesolithic and Neolithic (from 8000 to about 5000 years B.C.) times much of the Gulf floor would have been exposed…and the broad river valley with lakes and marshes in the flatter regions, would have formed a natural route for people moving westwards from east of Iran. Is this the route traveled by the ancestors of the Sumerians? Another example is that excavations at Ur and elsewhere have led to evidence of a flooding event at about 4000-3000 B.C. and it is tempting to associate the Sumerian `Flood' legend with the peak of the Holocene transgression during the flooding of the low-lying delta region when sea levels rose perhaps a few meters above present between about 6000 and 3000 years B.C.” (6)
The second theory, posited by Theresa Howard-Carter in the 1981 Journal of Cuneiform Studies, states that “the original Gulf inhabitants lived along the banks of the lower or extended Shatt al-Arab, ranging some 800 km across the dry Gulf bed. We can thus postulate that the pre-Sumerian cultures had more than ample time to be born and flourish in a riverine stetting, encouraged by the agricultural potential and the blessings of a temperate climate. The fact that the body of proof for the existence of these societies must now lie at the bottom of the Gulf furnishes at least a temporary excuse for the archaeologist’s failure to produce evidence for their material culture.” (7,8,9)
IV. Conclusion

Sea levels have a history of instability over time. Human societies have a long history of adapting successfully to the changes in sea level.

Notes:

1. Werner Nutzel: “On the geographical position of as yet unexplored early Mesopotamian cultures” in Journal of the American Oriental Society, volume 99, Number 2, April-June, 1979, pp. 288-296. Available for purchase online at: http://links.jstor.org/sici?sici=0003-0279(197904%2F06)99%3A2%3C288%3AOTGPOA%3E2.0.CO%3B2-4; accessed May 6, 2007.
2. “RV Meteor” is owned by the German Ministry for Science and Education and is operated by the German Science Foundation. For more information, see: “IFM-GEOMAR at: http://www.ifm-geomar.de/index.php?id=1402&L=1; accessed May 6, 2007.
3. Hans J. Nissen: The Early History of the Ancient Near East: 9000-2000 B.C., translated by Elizabeth Lutzeier, with Kenneth J. Northcott, University of Chicago Press, 1988, p. 55.
4. Nutzel, p. 289.
5. Ibid, p. 291.
6. K. Lambeck, P. Johnston, C. Smither, K. Fleming and Y. Yokoyama: “Late Pleistocene and Holocene Sea-Level Change: The Persian Gulf”, 1995. Available online at: http://wwwrses.anu.edu.au/geodynamics/AnnRep/95/AR-Geod95.html; accessed May 7, 2007.
7. Theresa Howard-Carter: “The Tangible Evidence for the Earliest Dilmun” in Journal of Cuneiform Studies, Volume 33, Number 3/4 (July - October, 1981), pp. 210-223.
8. “Prehistoric Deluge” at: http://en.wikipedia.org/wiki/Deluge_(prehistoric); accessed May 7, 2007.
9. For more information on the Shatt-al-Arab, see: SEMP Biot #152: “What is the ‘Thalweg Principle’” December 18, 2004. Available at: http://www.semp.us/publications/biot_reader.php?BiotID=152&Letter=; accessed May 7, 2007.