Science in Christian Perspective



Geology and the Great Flood

From: JASA 13 (December 1961): 117-119.

Many Christians accept the idea that a single flood swept, in the day of Noah, across the entire surface of the earth, submerging even such lofty peaks as Mt, Everest. Many scientists have doubted this story, for two reasons: (1) there is neither a known source from which to draw such fantastically large volumes of water, nor a place to store it after the flood has subsided, and (2) there has not seemed to be any particularly convincing geological evidence in favor of such a flood.

Christian authors have sought scientific support for a strict, literal, interpretation of the Bible account, among the facts of geology. This search has led to rather ludicrous results. Various writers have cited, as proof of Noah's flood, Pennsylvanian beds (deposited about 3 x 108 years ago), as well as rocks which were formed at other times, both earlier and later than that.

Scientists have, in many cases, used their scorn for the flood story as a means of casting doubt on the authenticity of the entire Bible.

Although scientists and theologians have been able to resolve their differences in many fields, the flood narrative has presented an apparently insoluble problem.

Recent results in the earth sciences, however, now raise the hope that perhaps here, again, the historians who wrote the early books of the Bible will be vindicated. It may well be that some Christians will not be pleased with the result; on the other hand, the present agreement beween the observations of geology and the Bible story confirms the latter as well as the nature of the Genesis account will permit.

Many geologists may not be pleased with the results, either. Traditionally, geologists have thought that earth history, over the last 25,000 years or so, was sufficiently well documented to preclude anything remotely resembling the Noachian deluge. The present report is based on a modification of each of these extreme points of view. However, it is thought that in no sense is either

*Dr. Tanner is Associate Professor of Geology at Florida State University, Tallahassee.

the Bible account, or the geological record, undermined or diluted.

The science-oriented Christian must admit, in the first place, that God is quite capable of performing miracles. It is not necessary, therefore, that the total amount of water on and in the earth be conserved. God can create any necessary additional amount, and likewise can later dispose of the surplus. If, however, we can see both a science-based mechanism, and a miraculous mechanism (i.e., one not understood or apparently mechanically contradictory), we should choose the former. This is because God is not capricious; He does operate within the framework of His own laws; and science is, in the final analysis, merely a study of the behavior of those God-ordained laws which affect the physical universe. A decision to accept the scientifically plausible explanation, rather than the scientifically illogical one, does not prove anything one way or the other; it merely shows that we think that the same God who guided the writing of the Bible account also established the laws which govern the day-to-day operation of the universe. In other words, the best answers which we are able to obtain are those that fit into both realms of thought: the Biblical, and the scientific.

If the Bible states flatly, beyond any possible argument, that 100% of the presently-known earth was inundated, we must face the alternative: a miraculous act of some kind. The Genesis account, in translation, does use the word "all." Our interpretation of this word must be colored, however, by other uses of the same word. For example, in Luke 2:1-3 we read that Caesar ordered "all" the world to be enrolled (that is, counted for census and tax purposes), and that "all" the world was, consequently, enrolled. It should be fairly clear that the Incas, Aztecs, and Eskimos were not affected by this order, and that probably large numbers of people in Australia, Asia and Africa never heard of it either. The usage here is essentially that of "all the world that is pertinent to the discussion," which is roughly, but not precisely, the same thing as saying "all the known or civilized world." Such a usage of "all" is standard in spoken English today. When we say, "Everybody's doing it" (whatever "it" may be), we do not mean "100%." The same thing is true in other languages, and particularly true in languages which have not (or had not) been influenced by scientific concepts. The notion of "100,7o" (mathematically pure and complete) is largely a scientific idea, and should not be forced onto other types of communication. The statement, "All have sinned, and come short of the glory of God," is something else again. This deals with a spiritual principle, is reiterated many times in various forms, and does not admit of an exception.

In the case of Noah's flood, we must choose between the two uses. The physical, non-mathematical one (i.e., "all of the world pertinent to the discussion") is to be preferred.

The foregoing treatment of the meaning of "all" would be pointless if there were no other evidence bearing on the problem. Fortunately, there is other evidence, and the notion of "all of the world pertinent to the discussion" is therefore significant.

The Bible does not provide precise date so for the events in the early chapters of Genesis. Bishop Ussher's famous dates are only minimum dates; that is, they represent a summation of the recorded events, and hence the least possible time in which those events could have happened. They do not allow for events which Bible writers thought unimportant or not germane, and therefore may, or may not, be accurate dates. It is interesting to note that Ussher's chronology places the Noachian flood at about 5 X 103 years ago, or even further back. Any important flood which occurred appreciably later than about 5 x 103 years ago is, apparently, not the flood discussed in Genesis.

One other general fact emerges from the Bible account. Man was, at the time of the flood, practicing agriculture. This development occurred, according to the most reliable archeological estimates, between 7,000 and 9,000 B. C.-that is, 9 to 11 x 103 years ago (Braidwood, 1960). The Ussher chronology, plus the limit placed by the advent of agriculture, restrict us to a period between 11 x 103 and 5 x 103 years ago. Of course these dates are not precise, but they may prove useful.

General information obtained from the Bible story includes the fact of severe, prolonged, wet, stormy weather. This, also, may prove useful.

One important fact is not provided. The Genesis writer states that the flood receded, but we do not know whether or not the water level actually returned to its original position. It is quite possible that, after Noah and his family disembarked, sea level stood higher than it had before. The Bible does not clarify this point.

Recent geological research contributes a considerable body of information to the discussion. Radiocarbon dates from the Gulf of Mexico area (including the Mississippi River delta) show that an extremely rapid rise in sea level began about 12 x 103 years ago (Fairbridge, 1960). This rise continued until roughly 9 x 103 years ago. During this period, sea level was changed by about 400 feet. The average rate of rise was close to 1.5 inches per year (about 12 feet per century). At the end of this period sea level stood about 50 feet below its present position. The water for the rise was provided by partial melting of the major ice caps and glaciers of the world.

A reversal of the climate trend (back toward more snow and ice) lowered sea level temporarily, until it reached a position approximately 100 feet below the present level, roughly 8 x 103 years ago. Between that date and about 6 x 103 years ago a warming trend sent sea level up to within 15 or 20 feet of the modern position. This was, likewise, a rapid rise, and an erratic one. The average rate was only about five feet per century, but much of this rise may have been concentrated in relatively short periods of time at rates perhaps as rapid as one or more feet per year. No precise geological figures are available on this point.

At approximately 2 X 103 years ago sea level stood at minus five feet. It has risen slowly and somewhat irregularly since then, and apparently is still rising. If estimates of present ice volume are correct, a complete melting would result in a rise to about 300 or 350 feet above the present level. Such a rise, if fairly rapid, coubi be quite disastrous.

A summary of the geological data shows two rapid rises, separated by a fall of about 50 feet, with the second rapid rise followed by a slow rise up to the present. Of the two rapid rises, the second appears to coincide with the general interval available for the Great Flood, as established by Bible chronology and general archaeology. This agreement between the two lines of evidence may make a solution possible.

Geological Events     Thousands of years ago       Events
Rapid rise begins                          12 
                                                    11                           )
Rise ends; fall begins                     10                           ) First Agriculture?
                                                      9                           )
Rapid rise begins                           8
Rise slows down                            6
                                                      5                            Chronology Limit?
Slow rise                                        4                            Abraham
Slow rise                                        2                            Birth of Christ
Slow rise; levelling off ?                   0

The accompanying table compares the two sequences of events, as obtained from geological evidence, on the one hand, and from archeological and Biblical evidence, on the other. Noah's flood apparently must be fitted between the italicized items. The agreement is excellent, considering the limitations of the method of study.

This preliminary comparison allows examination of a possible geological setting for the Great Flood. Sea level was rising rapidly from about minus 100 feet to about minus 20 feet. The climate was becoming warmer, and the moisture capacity of the atmosphere correspondingly greater. The latter suggests, for non-glacial regions such as Asia Minor, the possibility of more rain, perhaps (temporarily) extended periods of extremely heavy rain. Wet periods, covering very much of the world, coupled with a warming trend, should accelerate glacial melting, and produce short, fairly sharp, rises of sea level.

The pre-flood civilization described in the Bible was probably centered in the valley of the Tigris-Euphrates river system. There the relief of the land is low, largely because much of the area is constructional, built up of river sediment. A low, smooth, nearly flat alluvial plain of this kind is easily covered, to relatively large depths, by a slight rise in water level. A typical alluvial or deltaplain gradient is only one or two inches per mile at the lower end. A water level rise (for example, during a severe storm) of 15 feet would translate the zero contour to a point about 100 miles inland. If the gradient of the plain were much steeper, perhaps as much as four inches per mile, a 15-foot rise would move the shore line about 50 miles inland.

The entire low-land length of the drainage system is only about 400 miles (straight-line measurement; not winding river length) at the present time. A disastrous river flood, coupled with a rise and advance of stormdriven sea-water, could inundate the entire valley, sweep everything man-made away, leave nothing (within an area of roughly 105 sq. mi.) visible above the water surface, and drown the entire population of the area (with the exception of people who were already on or near well-provisioned boats). Combine this with an extended torrential down-pour, and we have a pretty fair picture of what may have been the flood story.

When the waters receded, the face of the plain would have been unrecognizable, for several reasons: (1) Storm tides, along the Persian Gulf, would have severely eroded the coastal areas; (2) Various rivers, during the high-water stages, would have changed their courses (a well-known geological fact); and (3) Much of the plain would have been plastered with new alluvial deposits, possibly several feet thick. Furthermore, by the time man could re-inhabit the plain, rising sea-level would have buried relatively large areas which previously had been cultivated.

Similar catastrophes must have occurred in the earlier, longer, sea-level rise (from 12 to 10 x 103 years ago). Man was not, at that time, a farmer. Since he was more or less nomadic, he would not have been anchored to cultivated fields, probably would not have preferred the deltaic end of the valley, and would not think of the sea level rise as a disaster.

The incident of the birds, and the tree leaves, as recounted in Genesis, is revealing. Burial of leaves under water, for long periods of time, is fatal. The green branch was either a direct miracle, or the bird found it on an unharmed tree growing on adjacent hills, perhaps 100 or more miles away.

We do not know the path taken by the drifting ark. One would infer that it, eventually, drifted sea-ward, rather than upstream against the flood-time river current. Where it finally struck land we do not know. The traditional identification of the spot with a mountain in Turkey does not, at the present moment, seem to have any validity.

A combination of sea-level rise, rapid glacial melting, torrential rains, and widespread floods would affect, primarily, coastal areas and the down-stream ends of river valleys. The entire world would have been so affected. Man probably had not spread over the entire world; the Bible account does not clarify this point, but geological and glaciological evidence do. However, wherever he was, along the waterways and coasts (which provided the only good means of transportation), he must have suffered the same fate.

The hypothesis advanced here distorts neither the geological, nor the Biblical, picture. The result is not a 100% universal flood, with water 30,000 or more feet deep over the modern coasts. The Bible, however, does not require such a flood. Falling back on minimum Bible requirements, we find a reasonable agreement with the best evidence provided by geology. The relatively simple, straight-forward picture which emerges is not miraculous. But it does tend to show that Bible history is completely reliable. That, in itself, is a worth-while result.


Braidwood, Robert J., 1960: "The Agricultural Revolution," Scientific American, September, pp. 130-148.
Fairbridge, Rhodes W., 1960: "The Changing Level of the Sea," Scientific American, May, pp. 70-79.