Some of the most maligned scientists, historically, are the diluvialists, who pursued the notion that a Noachian flood once covered the Earth. Today, we commonly assume that diluvialist geologists of the early 1800s simply wasted their time scientifically--pursuing research that had no hope of contributing to scientific knowledge because it was misguided and, ultimately, wrong.

In fact, the notion of a worldwide flood had been proposed earlier and accepted, though not in a religious context. In the late 1700s to early 1800s, Abraham Werner worked with the idea that rock layers represented sedimentation from an early ocean that later withdrew. Minerals and other rocks formed out of solution, like crystals. Werner's school was immensely productive over many decades. It especially helped the mining industry (which supported its research) in locating mineral beds. The primary difference between Werner and the diluvialists was just the particular timing(s) of flood waters.

The diluvialists made at least two significant and lasting contributions to geology--raising awareness of two sets of phenomena that might have gone unnoticed without the "bias" introduced by Biblical thinking, and collecting observations with a corresponding motivation.

The first began with William Buckland's award-winning discovery and research on fossil assemblages. Buckland was appointed to the first chair of geology at Oxford University in 1814. In 1821 he examined the newly found Kirkdale cave in northern England. The cave floor was littered with bones, some half-buried in dried silt. Buckland made the obvious inferences that the cave had formed first, the bones deposited next, and then the mud. The silt, he reasoned further, must have come from a flood, which he equated with the Noachian deluge. The bones included hyenas, rhinos, and elephants--animals not found in England. Reasoning that the large animals could not have entered the cave through its narrow opening, Buckland concluded that he was walking in an antediluvian hyena den. The mixed collection of fossil bones allowed him to reconstruct the world before Noah. Buckland's research earned him the Royal Society's highest honor, the prestigious Copley Medal, in 1822--the first time it was ever awarded for geological work.

Buckland's work inspired similar research, even across the Channel in France. Unfamiliar ancient fauna in each area became evident. It soon became clear that if there had been a flood, there had been many floods, burying bones in caves at different times. Some came to see Noah's flood as the last of many. The Earth may have been much older than once imagined, but the evidence for flooding certainly concurred with Biblical testimony. Buckland himself was later able to divorce his own discovery from the explanation he had originally assigned to it. His discovery and all those he inspired nevertheless remained.

The second major contribution of diluvial geologists involves what we now call glacial erratics--large boulders up to several tons that did not match the underlying bedrock or nearby elevated strata, but which sometimes matched rock far away. In one case, boulders in central England were traced to Norway! Had the rocks really moved? How? Visible scratch marks in the underlying bedrock supplied the first clues to their origin. The deep grooves were likely vestiges of scouring by the huge rocks, which would have been moved in catastrophic movements of water, such as during a worldwide flood. Such immense floods would seem implausible, of course, were it not for independent accounts in Biblical narratives.

Other phenomena confirmed the geologists' conclusions. Piles of rocks lined some hillsides, as though left by water. Charles Darwin, a young emerging geologist, explained one such set as the successive shorelines of a receding ocean. In other places, mixtures of large rocks and fine-grained silt indicated former turbulence. Many of these observations were found in open, rounded valleys, such as might result from the erosive action of powerfully moving rocks.

Diluvialists focused on these phenomena with meaningful vigor. They documented where the enormous boulders occurred and where they had come from. Later, their collected informa-tion would be invaluable evidence for another interpretation: that these rocks had been moved by glaciers. The glacier hypothesis at first was far less plausible, however, and was viewed with proper skepticism. After all, how could a sheet of ice move, since it was not fluid like water? Ultimately, the concept of glaciers, championed by Louis Agassiz, was able to explain the particular location of erratics and numerous other small facts. And most diluvialists acknowledged the broader evidence and adopted the once implausible glacial theory.

No well informed geologists now accepts the diluvialist hypothesis, but it is hard to discount how it contributed to building current knowledge. How could a hypothesis that seems misleading (in retrospect) have been so productive? Trial and error, conceptual change, and theoretical development are all integral parts of science as a process. Should religion alone be singled out for criticism?

Diluvial geology is an occasion for several important lessons about science. First, motiva-tion and guiding ideas are important elements of research. Without these, science does not even begin. Second, science is not just about having confirming evidence. Evidence may support several conflicting hypotheses at the same time. Hence, scientific controversies arise. When students master the basics of the relevance of observations, they are ready to learn, on a more advanced level, how scientists resolve conflicts among competing interpretations of the data. Finally, scientific knowledge changes. New observations do not always fit conveniently as mere additions within the framework of an early theory. Human imagination allows us to perceive different or more complex patterns that wholly reconfigure and unify the information. The former theories, while not completely "wrong," may still grossly mislead us outside a certain domain. In these three ways, diluvial notions once promoted good science. Valuable lessons lie hidden, here, though they may best be learned elsewhere first, outside a religious context with strong emotional overtones.

References

• Gould, Stephen Jay. 1985. "The Freezing of Noah." In The Flamingo's Smile. New York: W.W. Norton. pp. 114-25.
• Hallam, Anthony. 1983/1990. "The Ice Age." Great Geological Controversies. New York: Oxford Univ. Press. Chap. 3.
• Laudan, Rachel. 1987. From Mineralogy to Geology, Chicago: Univ. of Chicaago Press.

updated: 6/20/07