The Rocks Don't Lie: A Geologist Investigates Noah's Flood (15 page)

Despite the popularity of Ussher’s chronology, dozens of biblical analysts offered competing claims. Their disagreements illustrate the inherent difficulty in pinning down the meaning of even literal interpretations of the Bible. Depending on the reader and what else he or she brings to the table, two people may arrive at different meanings. After Steno, natural philosophers began to pursue increasingly independent approaches, piecing together earth history directly from reading the rocks.

The influential Baron Georges-Louis Leclerc, Comte de Buffon and director of the botanical gardens in Paris, argued that the world was at least ten times older. Born into a family of wealthy French aristocrats, Buffon inherited the family fortune at a young age, giving him the freedom to study law before he turned to mathematics and natural history. When he became keeper of the king’s garden in Paris in 1739, he converted it into a center to pursue his research interests.

In 1749, after a decade of study, Buffon proposed that Earth was created when a comet smashed into the Sun and knocked loose a molten fireball. The cooling of this piece of the Sun to form our world was described in the first installment of his massive thirty-four-volume
Histoire Naturelle
. After the flaming blob cooled into a rocky satellite, a universal ocean receded to expose the continents. Buffon denied that Noah’s Flood ever occurred and suggested that animals evolved based on otherwise enigmatic vestigial organs that served no apparent purpose, like the sightless eyes of a mole and the wings of flightless birds.

Two years later, in January 1751, the theological faculty of the Sorbonne sent Buffon a letter calling him out for more than a dozen reprehensible ideas. Among Buffon’s heretical notions were that currents scouring the bed of the primeval ocean shaped mountains and valleys, that topography was made by erosion rather than by God, and that eventually erosion would grind mountains down to sea level. Faced with the same choice that confronted Galileo, Buffon chose to recant and keep his prestigious position. He renounced everything in his book “respecting the formation of the earth, and in general all which may be contrary to the narrative of Moses.”
¹

Shaken but undeterred, Buffon experimented with how long it took to cool spheres of molten metal. He determined that the first day of Creation had to have lasted more than twenty-five thousand years for the planet to cool to the point where water could settle on it. Based on rainfall rates, he calculated that the second day must have lasted ten thousand years to build up the primordial seas. His concluding estimate was that the world must be about 75,000 years old to have cooled to its present temperature. This time, when Buffon included this estimate in his
Introduction to the History of Minerals
in 1775, he escaped theological condemnation.

Three years later, Buffon expanded on the idea of an ancient Earth in his
Epochs of Nature
. He argued that the days of Creation were figurative and corresponded to geological ages, while cautiously refraining from publishing his own opinion that the world was millions of years old. The first of his great epochs saw the formation of Earth and other planets. During the second epoch Earth’s rocky interior consolidated, releasing volatile substances to create the atmosphere. During the third epoch, about thirty-five thousand years after the planet formed, continent-covering seas deposited stratified rocks, coal, and marine fossils. Rushing currents circulating on the bottom of this great sea carved modern topography. Volcanoes became active in the fourth epoch. He offered Siberian fossil elephants (mammoths) as proof that even the poles enjoyed a tropical climate during the fifth epoch. In Buffon’s sixth epoch the modern continents formed as the intervening land collapsed to form ocean basins. Finally, the arrival of mankind ushered in the world we know roughly six thousand years ago.

Although he did not grant Noah’s Flood any place in his geologic history, Buffon did point out that there was no conflict between Genesis and geology if one did not take the days of Creation literally. He thought, just as some theologians had argued, that Genesis was written for uneducated people and should not be interpreted literally on matters pertaining to earth history. It was never intended to convey scientific truths.

Again, the church remained silent, torn by internal controversy over how to interpret Genesis. Unlike Galileo, this time Buffon escaped censure because influential theologians were themselves toying with the notion of an old Earth. Catholic opinion in France was divided about how to interpret Genesis. Even those in positions of authority were now willing to consider the idea that the six days of Creation might refer to geological ages.

Among Buffon’s correspondents was Joseph Needham, the first Roman Catholic priest elected to Britain’s Royal Society. In embracing Buffon’s view that each day in the week of Creation represented more than twenty-four hours, Needham pointed out that even sixty million years represents an infinitesimal portion of eternity. Theologians were starting to waver on a six-thousand-year-old Earth.

As the idea that geologic time involved more than a few thousand years became reasonable, Abraham Werner, a charismatic professor at the Freiberg Mining Academy, began popularizing the idea that the rocks revealed that earth history consisted of four periods. Werner’s father, a Saxon foundry inspector, had passed on to his son a keen interest in minerals, and at the age of twenty-five Werner published an influential field guide that landed him a professorship at the Freiburg School of Mines. Five years later he offered the first course in historical geology. A gifted lecturer, Werner’s influence grew as his students dutifully spread his ideas about geologic history across Europe.

A lab man who wanted to understand earth history from the study of minerals and rocks without all the bother of fieldwork, Werner adopted Buffon’s view that our planet formed when a stray comet smashed into the Sun, spinning off a fireball that slowly cooled to become covered by a universal ocean. He proposed that the primary (crystalline) rocks precipitated from this global sea, accounting for marine fossils found high in mountains. Neptunists, as Werner’s disciples were known, attributed deposition of the secondary (layered) rocks to material settling slowly to the bottom of the drying sea. They saw the signature of Noah’s Flood in the sculpting of topography, and the deposition of the tertiary rocks that were made of gravel, sand, and clay derived from erosion and redeposition of the primary and secondary rocks. On top of all this was a fourth, or quaternary, level of unconsolidated sand and gravel eroded off uplands by running water, like the deposits of modern rivers. In short order, these four divisions were found to adequately describe the rocks of other mountain ranges, like the Apennines and Caucasus.

As this crude geological system began to formalize the basis for evaluating the thickness, lateral extent, and relative age of rock formations, it became apparent that irregular boundaries (unconformities) separated geological eras. And yet individual layers within the secondary rocks could be traced across Europe. Delicate layers just a few centimeters thick could be traced across tens of kilometers, something impossible to attribute to a chaotic deluge that ripped apart and mixed up the world’s surface in the way that Burnet and Woodward had imagined. Werner’s dominant influence on geological thinking meant that layered rocks were no longer all thought to date from the Flood. Now it was just the tertiary rocks and the form of the land itself that testified to the Flood.

A few years later, in 1788, James Hutton’s startling discovery on a windswept stretch of Scottish coast went a step further in proving that earth history was more complicated than allowed by a literal reading of Genesis. At least two rounds of deposition and erosion were required to account for the deposition and deformation of the sandstone beds at Siccar Point—meaning that there were either two independent rounds of Creation, or Earth reshaped itself every now and again.

The son of a successful merchant, Hutton lived comfortably while studying at the University of Edinburgh. Upon graduation in 1743, at the age of seventeen, he apprenticed to a solicitor, offsetting the drudgery of copying wills and contracts by distracting coworkers with occasionally calamitous chemistry experiments. By the end of the summer Hutton’s experiments had exhausted his employer’s patience. That fall he reenrolled at the university, this time as a medical student. In 1747 he left Edinburgh to continue his studies, starting in Paris and finishing two years later with a medical degree from the University of Leiden (Steno’s alma mater).

Despite his medical training, Hutton never seriously considered practicing medicine. Insatiably curious, he continued studying chemistry before turning to geology. Inspired by a favorite experiment, Hutton started a company with a former classmate to use chimney soot to make sal ammoniac (ammonium chloride). This key component of metalworking flux otherwise had to be imported from Egypt. The scheme was brilliant. Chimney sweeps were thrilled to get rid of soot, and metalworkers were glad to have an affordable and reliable supply of an essential ingredient. In combination with his inheritance, the profits meant Hutton need not work, which left him plenty of time to pursue his many other interests.

At first, Hutton devoted himself to his family’s farm. Set on 140 acres just north of the English border, it lay on some of the best land in Scotland, where rolling hills carved out of volcanic rock produced rich, fertile soil. In contrast to Darwin’s epic voyage around the world, Hutton began forming his radical ideas about the age of the world by watching the dirt wash off his fields.

As he learned to read the land, he translated his love of chemistry to agriculture, developing ways to use calcium carbonate to enhance soil fertility. He also tried to retain the soil eroding off his bare, plowed fields by enclosing them behind stone walls. Stacking blocks of sandstone quarried from nearby hills, Hutton couldn’t help but recognize the similarity between the mineral grains leaving his fields and those that composed the rocks he piled.

There, in his hands, below his feet, and before his eyes, lay the keys to a grand cycle in which rocks eroded and the resulting sediment was deposited elsewhere and buried deep enough to reform into new rock. Most rocks in Britain are made of sediments eroded from somewhere else, and everywhere above sea level is eroding. Neither idea was new—Leonardo had long before recognized the nature of sedimentary rocks, and most farmers were familiar with erosion. But Hutton did something new: he put these ideas together, seeing them as two halves of a grand cycle. Here was the foundational insight behind his radically original concept of deep time.

Such a cycle presented a dilemma. Without a way to restore eroded material, the soil would eventually disappear and, along with it, the fertility of the land, something a benevolent creator would not allow. What could refresh the land after erosion wore it down?

After setting up his farm, Hutton moved back to Edinburgh in 1767. He arrived in a city on the cusp of an intellectual renaissance. The Scottish aristocracy that backed Bonnie Prince Charlie’s failed attempt to claim the throne had been purged, dismantling class distinctions and ushering in a new egalitarian spirit that fostered innovative thought. The new intellectual culture that sprang from the ruins of Edinburgh society nurtured Hutton’s curiosity and interests.

At the time, most natural philosophers thought rocks precipitated out of Werner’s drying primeval ocean in a global version of those grow-your-own crystal sets. But Hutton’s continual experimentation with mineral chemistry convinced him that rocks contained a lot of material that would not dissolve in water. How could rocks precipitate out of a drying sea if they could never be dissolved in the first place? And if Werner’s conventional wisdom about how minerals formed was wrong, then what could be responsible for solidifying rocks? Hutton theorized that the combined effects of heat and pressure offered the only viable alternative. Both would be available at the bottom of a pile of sediment—as long as the pile was thick enough.

In 1784 the newly chartered Royal Society of Edinburgh invited Hutton, then nearly sixty, to present his theory of the Earth, forcing him to gather his thoughts into presentable form. He did not give his own lecture, whether due to illness or a bad case of nerves. His best friend, Joseph Black, who had recently discovered carbon dioxide, graciously read it—the tradition being that lectures were written up in advance and simply read aloud at the meeting. Black presented Hutton’s ideas about layered rocks being made of sediment eroded off of previous land, and how heat and pressure were required to form rocks, as well as the case for rejecting Werner’s ideas about rocks precipitating from an ancient sea. Ignoring the Bible and the Flood, Hutton had inferred that the world was unknowably old. Instead of a grand catastrophe to explain the world, he invoked the subtle day-to-day action of wind, rain, and waves that he himself had observed.

Four weeks later, Hutton personally read a second lecture. He finished his critique of Werner’s theory and focused on how to get stratified layers of rock back to the surface after they solidified at the base of a thick pile of sediment. If rocks just precipitated from a shrinking ocean, then they should all lay horizontal. Yet it was well known that some layered rocks lay steeply inclined. Instead of invoking worldwide collapse during Noah’s Flood to explain the tilted layers (as Steno had), Hutton literally turned the problem on its head and proposed a different action—Earth’s internal heat and volcanic action was what deformed rocks. The key to his argument was how granite veins cut across layered rocks. If, as he thought, granite began as molten rock that rises up from the overheated base of a sedimentary pile, granite veins in cracks and fissures should cut across the layers in the rocks they pushed up through before cooling. Hutton saw this basic process as the force driving a grand cycle of regeneration in which the sea and land continually changed places—continents eroding into oceans to form great piles of sediment that eventually melted at the base and rose anew.