Yes, Noah’s Flood May Have Happened but Not over the Whole Earth 

Lorence G. Collins   Department of Geological Sciences, California State University Northridge

The Bible (Genesis 6-9) describes a worldwide flood (the Noachian Flood), covering even the highest mountains of the earth and the construction of a huge boat (a rectangular box-like craft) that transported animals, at least two of a kind of all land animals on the earth.  The Qur’an (the bible for Muslims; Suras, chapters 11 and 71) has almost a duplicate story with a similar huge boat that transported animals and a worldwide flood.  In addition two older stories exist in ancient Babylonian epics that describe a huge flood.  One is the Epic of Gilgamesh, describing a flood on the Euphrates River (Gilgamesh).  The other is the Epic of Atrahasis, which has a huge flood on the Tigris River (Atrahasis A).  In the Epic of Gilgamesh, Gilgamesh is warned that a god plans to destroy all humanity and is told to build a ship to save him, his family, friends, and cattle.  In the Epic of Atrahasis a tribal chief survived with his family by floating in a boat down to the Persian Gulf.  After the flood subsided, the chief got out on dry land and erected an altar and made sacrifices to a water god so that such a flood would not happen again (Atrahasis B).  Noah also built an altar when he got off the Ark and offered burnt sacrifices (Genesis 8:20).  Because these stories all describe an ancient huge flood in Mesopotamia, it is extremely likely that a huge flood could have occurred.  However, the next question is:  “Did the Noachian Flood cover the whole earth?” 

Scientific evidence against a whole-earth flood
The Bible says that the rains that created the Noachian Flood lasted for 40 days (Genesis 7:17), that the waters prevailed on the earth for 150 days (Genesis 7:24), and after these 150 days the waters gradually receded from the earth so that by the seventh month and the seventeenth day, Noah’s Ark came to rest upon the mountains of Ararat (Genesis 8:4).  A year plus two months and twenty seven days later the earth was dry enough so that Noah, his family, and the load of animals could disembark from the Ark (Genesis 8:14).  Because this flood was intended by God to destroy all flesh on earth (Genesis 6:13) and because sedimentary rocks on all continents contain fossils that supposedly represent the “destroyed flesh of all life,” it might be thought that the Bible story, describing a whole-earth flood, was true.  However, interlayered with these fossil-bearing sedimentary rocks on all continents are layers of evaporite rock salt (sodium chloride), gypsum (hydrated calcium sulfate), anhydrite (calcium sulfate), and various potash and magnesium salts, which are associated with red beds (shales) containing fossilized mud cracks (Schreiber and others 2007).  Many of these mineral compounds and red beds have combined thicknesses on different continents of more than one kilometer (~3,281 feet) (Collins 2004).  The red beds are red because they contain red hematite (iron oxide) which formed from magnetite grains that were oxidized while the muds were exposed to oxygen in open air.  The mud cracks can form only under drying conditions that cause the mud to shrink and form polygonal cracks.  The evaporite mineral compounds in the layers are deposited in the correct chemical order that corresponds to the solubility of each kind of ion in these compounds and whose increasing concentrations during the evaporation of water would cause them to precipitate in a predicted depositional sequence as the water volume decreased.  Such evaporite deposits would be expected to occur where a marine sea was once present and which disappeared when the sea became completely dry.  Therefore, one could expect these evaporites to be at the top of the supposed Noachian Flood deposits when the water supposedly receded and the land dried out, but certainly not in different levels in between older and younger fossiliferous “Flood deposits.”  We read in the Bible that there is only one time in which the Flood waters are said to recede and leave the earth dry.  That is, no multiple worldwide climatic conditions are described in which flooding, then drying to a dry earth, more flooding, more drying to a dry earth, in repeated cycles occur over and over again in that Flood year.  On that basis, it is logical that all the kinds of evaporite deposits and red beds in many different levels in the supposed Noachian Flood deposits could form only in local climates with desert drying-conditions and could not have possibly formed at the same time in which a flood covered the whole earth for more than one year (Collins 2004).  On that basis, the Noachian Flood story cannot describe a whole-earth flood, but it could only represent a large flood in a local region of the earth. 

Local evidence for the Noachian Flood and similar floods
Two rivers, the Euphrates and Tigris flow through Mesopotamia, which is now the country of Iraq (Fig. 1).    There are several layers in exposed rocks near these two rivers in southeastern Mesopotamia (Iraq) that are likely flood deposits.  Most are about a foot thick, but one is as much as 11 feet thick (MacDonald 1988).  Flood debris from this same thick deposit along the Euphrates River near the ancient Sumerian city of Shurappak about 125 miles southeast of Baghdad has been dated by archaeological methods, giving an age of 2900 BC (Scholars).  Flood deposits 8 feet thick are also reported by MacDonald (1988) as far northeast as the ancient Babylonia city of Kish (74 miles south of Baghdad).  At any rate, the many flood-deposit layers show that flooding in southeastern Mesopotamia was not unusual in ancient times. 
Similar large local floods are common throughout history around the world.  For example, monsoon storms in Bangladesh frequently produce much rain over the country and in the Himalaya Mountains which rise in the northern part of the country.  Runoff of water from the rain and melting snow during such storms create great floods in four rivers that converge to a single river, the Wang River, which then drains into a huge delta in the Bay of Bengal (Bangladesh).  Thousands of people have been drowned in this delta region by many such floods during the last century.  Almost every culture through history has a flood story to tell, as would the people in Bangladesh, but in each of these times and places, the floods would have been local and not worldwide. 
Many creationists have pointed out that the Bible indicates that God promised not to cause another huge flood to occur and, therefore, there cannot be any floods that are similar to the Noachian Flood.  This promise is in Genesis 9:13-15 which reads: 
“13I have set my bow in the clouds, and it shall be a sign of the covenant between me and the earth. 14When I bring clouds over the earth and the bow is seen in the clouds, 15I will remember my covenant that is between me and you and every living creature of all flesh.  And the waters shall never again become a flood to destroy all flesh.” (English Standard Version) 

Why was the local large Flood possible?
Storms that occur in Mesopotamia usually come from the Mediterranean Sea, cross the mountains in Syria, Turkey, and western Iran northwest of Mesopotamia, move over Mesopotamia to the Persian Gulf, and then exit in the Gulf of Oman.  The Euphrates and Tigris Rivers that would transport water from these storms leave higher land in northern Mesopotamia and enter a nearly flat area about 80 miles north of Baghdad.  In this 80-mile interval the gradients of these rivers are about 1 foot per mile.  Both the Euphrates and Tigris Rivers near Baghdad have elevations of 100 feet above sea level, and at the city of As Samawah (174 miles south of Baghdad), the Euphrates River has an elevation of 30 feet (a drop in elevation of 70 feet) (Climate).  A similar 70-foot drop occurs along the Tigris River.  On that basis, the gradients of the two rivers in these intervals are about 0.4 feet per mile.  In the additional 223 miles to the Persian Gulf (sea level) the gradients are about 0.13 feet per mile.  Therefore, in both southeastern and mid-Mesopotamia the gradients are so low that the rivers are barely flowing downhill, and frequent flooding could be common. 
A large river has natural levees.  During a big storm, water rushing down the channel carries abundant sedimentary debris.  If the water in the channel overflows its banks onto the adjacent flood plain, the velocity immediately slows because of friction with the flat land, and the water at lower speed cannot carry its entire load of sediment.  Heavier coarser particles are deposited abruptly on tops of the banks adjacent to the river while finer silts and clay particles are transported onto the flood plain.  When such overflowing floods are repeated year after year, the deposited coarser sediments adjacent to the river build up natural levees on both sides of the channel.  Natural levees along the Euphrates and Tigris Rivers rise up to 10 to 15 feet above the river channels, and the surface of these levees slope gently away from the rivers for 3 to 5 miles to lower, adjacent, nearly-flat flood plains that are up to 65 miles wide (Tactical Pilotage Chart TPC G-4C, H-6A, and H-6B).  The people living in Mesopotamia in biblical times would have had their villages on the natural levees because the flood plains would have been swampy. 

What happened during the Flood?
The watershed for the Euphrates and Tigris Rivers on which the flood could have occurred extends for more than 1,000 miles from the Persian Gulf through Mesopotamia into Syria and Turkey and laterally for more than 600 miles from eastern Saudi Arabia to southwestern Iran – an area of more than 600,000 square miles.  On that basis, if abundant rain fell, not only in the mountains of Syria and Turkey, but also in Saudi Arabia and Iran, the tributary streams from these two additional countries would also contribute their volumes of water to the flood plains of the Tigris and Euphrates Rivers (Fig. 2).  Normally, in lesser storms most water runoff would have come primarily from the mountains in Syria and Turkey and not also from Saudi Arabia and Iran.  During the Flood, upstream where water first accumulates the depth of water on the flood plains may be barely over the tops of the natural levees, but downstream the water “piles up” because it does not flow very fast downhill on a nearly flat surface.  Therefore, downstream water depths could reach 20 feet or more above the tops of the levees.  This increase in depth would be particularly true where the two flood plains with a width of 170 miles in the northern section would be squeezed into a 135-mile width in the lower part of the drainage system where the two rivers join.  The joining of the two rivers would also increase the volume of the water in the flood plains, thereby increasing the depth.  At any rate, all higher land on the natural levees where the people in the villages were present would be completely submerged.  Thus, it would be possible for a flood to have occurred in mid-Mesopotamia, perhaps about 2900 BC, as evidenced by the dated flood deposits.    

Remnant evidence of the Flood
When the huge storm ceased that caused the Flood, there would have been huge lakes, and it could have taken months to drain the water in these lakes into the gulf.  Taking months could explain why the Noachian Flood took so long to recede (as much as one year, according to Genesis 8:14).  Evidences for this poor drainage are the present-day lakes in the flood plains.  Lake Hawr al Hammar, which is 20 miles wide and more than 50 miles long, lies on the flood plain of the Euphrates River west of Basra, and several other large lakes are on flood plains adjacent to the Tigris River (e.g., Hawr as Sa’diya and Hawr as Saniyalt).  The poor drainage would be caused by the fact that the water covering the flood plains would have no channel through which to flow, would not flow uphill over the sloping natural levees to re-enter the river channels, and the slopes of the bottoms of the lakes would have been nearly flat with gradients toward the gulf of 0.4 to 0.13 feet per mile.

Effects of the curvature of the earth
Because of the curvature of the earth, the horizon drops in feet per mile from where the viewer is standing.  However, the drop is proportional to the square of the distance in miles rather than to a linear mile (Math).  See Appendix 1 for examples of calculations.  From these calculations, it can be seen that a tribal chief (or Noah) standing on the deck of a large boat (Ark), perhaps 36 feet above the water, would not be able to see the tops of any hills 50 feet high as little as 16 miles away across flood plains covered with water.  The drop in the horizon because of the curvature of the earth prevents it.  Most hills, as much as 50 feet high, are more than 65 miles away from the river levees.  Therefore, the survivors of the Flood could see only water in all directions while they were floating down the Tigris River and over the flood plains.  Many of these hills would also be partly covered with water which would make their tops project less above the water level, and therefore, the curvature of the earth would make them disappear from the line of sight in even a shorter distance than 16 miles.  Northeast and southwest of the nearly flat surface that contains the two rivers, the topography rises to more than 1,500 feet in Saudi Arabia and in Iran (Media).  Calculations show that elevations of 1,500 feet high cannot be seen beyond 55 miles away, and these places are more than 100 miles from the Euphrates or Tigris Rivers.  Therefore, none of the high country in Saudi Arabia or Iran would be visible to a tribal chief (or Noah).  On that basis, the “whole world” would definitely appear to be covered with water during the Flood, and that was the whole world for the people in this part of southeastern Mesopotamia at that time. 

Ramifications of the Noachian Flood
If one were to speculate that there really had been a “whole-earth” flood, then Noah needed to get a pair of pandas from China, a pair of kangaroos from Australia, and a pair of armadillos from Texas, find a year’s supply of fresh bamboo shoots for the pandas and other specialized foods for many of the other animals on the Ark, and then return these animals to their respective continents when the flood was over.  Those conditions and requirements are scientifically not possible, particularly because Noah likely neither physically brought the animals to the Ark nor returned them.  Therefore, many of the animals living in and coming from distant continents would have had to swim both ways, which is very unlikely. 

If the 11-foot thick layer of flood deposits in southeastern Mesopotamia (MacDonald 1988) represents a huge flood of ancient times, and if it is the remnants of the one described in the early Babylonian epics, then the authors of these epics were likely survivors who lived in a village on natural levees on the lower parts of either the Euphrates or Tigris Rivers where the Flood water covered their village, natural levees, and adjacent flood plains for distances of 135 to 170 miles so that no land could be seen, and their whole world would have been under water. 
Because both the Bible and the Epic of Gilgamesh contain information about birds being sent out from a boat to seek land at the end of the Flood and because in both stories these birds include two doves and a raven in the Bible and a dove, a swallow, and a raven in the Epic of Gilgamesh, the same occurrence of both kinds of birds (dove and raven) does not seem to be a coincidence (Deem).  This correlation strongly suggest that the biblical Flood story was taken from the older Epic of Gilgamesh and was not an original report describing actual history experienced by Noah.  Nevertheless, both Babylonian epics could have supplied information that inspired the biblical author of Genesis to describe the events leading to, during, and after the supposed Noachian Flood.  The difference is that the biblical account provided a theological meaning to the people of the time for the rainbow (Genesis 9:13-15) and why some people were able to survive. 

I wish to thank Kevin Collins, Fred Tonsing, Eugene Fritsche, Warren Hunt, Jarvis Streeter, Steve Peralta, and Barbara Collins for helpful comments that greatly improved the manuscript. 

Atrahasis A. Available on line at:  Last accessed February 16, 2009.
Atrahasis B.  Available on line at:  Last accessed February 16, 2009.
Bangladesh. Floods in Bangladesh.  Available on line at  Last accessed February 17, 2009.
Climate.  Climate of Iraq. U.S. National Climatic Data Center. Available on line at  Last accessed February 23, 2009. 
Deem, R., 2008, Is the Biblical Flood Account a Modified Copy of the Epic of Gilgamish?  Available on line at  Last accessed March 16, 2009.
Gilgamesh. Available on line at  Last accessed February 16, 2009.
MacDonald, D. 1988. The Flood: Mesopotamian Archaeological Evidence: Creation/Evolution Journal, v. 8, no. 2, Spring, 14-20.
Math.  Available on line at  Last accessed February 16, 2009. 
Media. Available on line at  Last accessed February 25, 2009.
Scholars.  Available on line at .   Last accessed February 16, 2009.
Schreiber, B. C., Lugli, S., and Babel, B., 2007. Evaporites Through Space and Time, GSL Publishing Associates Limited, Cambridge, 373 pages.

Appendix 1
The drop in the horizon (curvature) does not vary linearly but with the square of the distance.  The formula is:  c = (2/3) times x2, where “c” is the curvature (drop) in feet and “x” is the distance in miles.  For a person who is 6 feet three inches tall, the eye level is about 6 feet above the ground. 
For 6 feet, we have:  6 = (2/3) times x2.  Then, x = 3 miles.  That is, at 3 miles, a 6-foot drop of the horizon occurs.
For a 6-foot person on a 45-foot high (30 cubits high) boat (Ark) that is 1/3 under water, we have a total height of:  6 + (45 times 2/3) = 36 feet.
Thus, we have: 36 feet = (2/3) times x2.  Then, x = 7.35 miles (a 36-foot drop at 7.35 miles)
For a 6-foot person at ground level looking at something 45 miles away, the calculations are:  45 miles - 3 miles = 42 miles.  Then, c = (2/3) times (42)2  = 1,176 feet,  Thus, he could barely see the tops of something 1,176 feet high.
If he were on a boat (Ark) at 36 feet above the water and looking at something 45 miles away, the calculations are:  45 miles - 7.35 miles = 37.65 miles.  Then, c = (2/3) times (37.65)2 = 945 feet.  Thus, he could barely see the tops of something 945 feet tall.
If the hills were 50 feet tall, as possibly occurs in high ground between the two river systems south of Baghdad, the calculations are:  50 = (2/3) times x2.  Then x = 8.66 miles.  Therefore, standing on a boat (Ark), he could barely see the tops of these hills at 8.66 + 7.35 = 16.01 miles, and such hills are more than 60 miles from the river levees.  Thus, just beyond 16 miles, the tops of these hills cannot be seen from the Ark.
If the elevations were 1,500 feet high, as occurs in eastern Saudi Arabia and on the steep slopes of the Zogras Mountains in southwestern Iran, the calculations are 1,500 = (2/3) times x2.  Then x = 47.4 miles.  Therefore, standing on an Ark, a person could barely see something at these elevations just 54.75 miles away (47.4 + 7.35), and these elevations are more than 200 miles away from the Euphrates River and more than 100 miles away from the Tigris River.

Lorence Collins is a retired professor of geology who has written extensively to promote general knowledge about geology and to counter arguments by anti-evolutionists, including three other articles for the RNCSE which also can be found at <>.

Fig. 1.  Map of Mesopotamia (Iraq).
Fig. 2.  Map showing elevation contours around the Euphrates and Tigris Rivers that extend NW-SE through Mesopotamia.