Chapter 1: The Geologic Mystery of the Tsangpo River

In the spring of 2002, I embarked on a journey to Tibet to unravel an intriguing geologic enigma: How did the formidable Tsangpo River carve the deepest gorge in the world amidst the towering Himalayas? Such origin inquiries captivate my interest. As a geomorphologist, my focus is on the formation of landforms and crafting scientific narratives that elucidate the processes that shaped them. For years, I thought my narratives were distinct from myths, rooted firmly in the tangible features of the landscape. That perception changed dramatically after my visit to the Tsangpo.

Upon landing in Lhasa, my team and I traveled southeast, traversing a frosty pass that led us into a tributary. As we made our way toward the main river, I was astonished to encounter vast flat surfaces, resembling enormous tables, poised high above the valley floor. These formations, known as terraces, typically develop when a river cuts into its bed, leaving older floodplains behind. However, many terraces I observed were layered with alternating silt and clay—deposits that seemed incongruous with the turbulence of a mountain river.

While bouncing around in our Land Rover, I meticulously recorded the heights of these terraces on topographic maps. I noted that, at certain points downstream, they aligned to a similar elevation, maintaining that height as the river descended, gradually increasing in height as the riverbed lowered. Later, at the confluence of this tributary and the Tsangpo, we found the terrace tops soaring hundreds of feet above the valley floor.

From this large-scale landscape puzzle, a narrative began to emerge: A primordial lake had once submerged the Tsangpo and its tributaries. Rivers flowing into this lake had created deltas, layering sediments into terraces that now marked the ancient shorelines of the lake. Yet, one critical question lingered: What had prevented all this water from draining down the Tsangpo gorge?

Could these two narratives—one cultural, the other geological—be different interpretations of the same event?

At the gorge's head, which plunges nearly 20,000 feet below the surrounding peaks, we discovered remnants of a glacial moraine—debris pushed downhill by glacial ice. Material was present on both banks of the Tsangpo, indicating that a glacier had advanced down a nearby mountain, forming a massive earthen and icy dam across the river. This dam had sealed the valley, causing the river to swell into a vast lake. However, the water-worn features of the moraine indicated that this barrier was not permanent. When it eventually failed, a torrent of water surged down the steep gorge at a staggering rate—surpassing even the Amazon's flow.

This revelation was thrilling. By interpreting the landscape, we had uncovered a grand geological saga thought to be lost to time. But that was not the end of our discoveries. One day, as we drove past a peak encircled by terraces, one of my graduate students shared a story he had read in a guidebook. The peak, he explained, was the site of a kora—a Tibetan Buddhist pilgrimage—marking the arrival of Buddhism in Tibet by the revered teacher Padmasambhava, also known as Guru Rimpoche. Legend has it that Guru Rimpoche converted the local people from animism through miraculous feats, including defeating a demon residing in a great lake—by draining it.

Guru Rimpoche is believed to have visited the Tsangpo in the eighth century, coinciding with the time the ancient lake we had discovered filled the valley, as indicated by radiocarbon dating of charcoal found in the terraces. I found myself contemplating the parallels between these two stories—one cultural, the other geological. Could they actually be retellings of the same incident?

The late geologist Dorothy Vitaliano introduced the term geomythology in the 1960s to describe oral traditions that explain unique landforms or reference geological disasters—earthquakes, floods, volcanic eruptions, and the like. Like many geologists, I had previously dismissed these narratives as mere fantasies, embellished with supernatural elements and cloaked in mythic language. However, there is mounting evidence that many geomyths are indeed rooted in actual historical events.

The tale of the great flood is one of the oldest and most widely recounted stories. Variants of this narrative exist across numerous cultures, so much so that some pseudoscientific theorists have suggested its prevalence as evidence for a global deluge. While these flood myths share common themes—catastrophic inundation and miraculous escapes, often by boat—the specifics of the floods differ significantly among cultures, revealing insights into local geological phenomena.

Flood legends from coastal communities, such as those in Fiji and Tahiti, recount sudden, colossal waves that strike from the ocean without warning or preceding rainfall. In central Chile, an ancient tale describes two powerful serpents competing to raise the sea, triggering an earthquake and subsequent flooding. In the Pacific Northwest of the United States, indigenous tribes narrate epic battles between Thunderbird and Whale, where the winged creature captures the sharp-toothed beast and drops it back into the water, creating massive waves that sweep canoes into treetops.

These accounts closely resemble the phenomenon of tsunamis. Historical records from Japan confirm that a major earthquake struck the Pacific Northwest on January 26, 1700, generating waves that reached as far as Japan. Archaeological evidence suggests that around this time, Native American communities abandoned their coastal villages from British Columbia to Oregon. In the myth of Thunderbird and Whale, it seems that survivors preserved memories of these tsunamis that forced them from their homes.

The Oldest Flood Myth and its Origin - This video explores ancient flood myths across various cultures, examining their origins and similarities.

Similarly, people living in Arctic and high-altitude regions, such as the Tibetans of the Tsangpo valley, have flood myths that appear to depict glacial dam failures. Norse mythology tells of Odin, the "allfather" of gods, and his brothers slaying the ice giant Ymir, whose watery blood flooded the earth. Although linking this mythical account to a historical event involves considerable speculation, it is plausible that Ymir's story originated from real ice-dam ruptures as glaciers retreated from Scandinavia following the Pleistocene.

A third category of flood narratives reflects the experiences of river communities, who recount tales of incessant rainfall and gradually rising waters. The biblical account of Noah from the Book of Genesis serves as a prime example. This Hebrew myth has its roots in an earlier Mesopotamian tale inscribed in cuneiform on a clay tablet unearthed from ancient ruins. The inscription tells of a righteous man warned of an impending flood meant to annihilate humankind, who builds an ark to save his family and animals.

I began to perceive science and mythology as two aspects of the same phenomenon.

There may be geological veracity behind this story as well. For instance, it is conceivable that heavy rainfall caused the Tigris and Euphrates rivers to overflow their banks, inundating the lowlands. Columbia University oceanographers Bill Ryan and Walter Pitman proposed another theory in the early 1990s. By analyzing sediment cores from the Black Sea's floor, they determined that prior to 5600 B.C., the sea was a large freshwater lake. As global sea levels rose due to melting polar ice, the Mediterranean overflowed a land barrier, cascading into the lake. This influx "roared and surged at full spate for at least three hundred days," as noted in their book, Noah's Flood, flooding the surrounding area at a rate 200 times that of Niagara Falls.

Ryan and Pitman speculate that this deluge quickly inundated a vast plain where some of the earliest farming communities thrived. Perhaps, they suggest, traumatized survivors migrated to Mesopotamia, bringing with them agricultural knowledge and a flood narrative that submerged their world.

On a subsequent trip to the Tsangpo valley in 2004, I shared with a local farmer our geological findings about an ancient flood that had drained a lake where her village now stands. She was already aware of the flood, having learned from the lamas at the local temple that when the lake emptied, it revealed fertile land for farming. She gestured toward the valley wall, indicating where the receding water had left three stranded boats.

We decided to visit the lamas, whose temple was situated high on a terrace overlooking the valley. A vibrant fresco inside depicted Guru Rimpoche hovering over a lake-filled valley. When we inquired about the flood, the head lama listened attentively but dismissed it as an old tale. However, he expressed curiosity about another geological mystery: Why, he asked, were there water-rounded rocks on nearby mountainsides? Did their presence not suggest that an ocean once covered Tibet's highest peaks?

As a geologist, I recognized that his hypothesis would not withstand scientific scrutiny. More likely, those smooth stones were cobbles left high on the valley wall when ancient rivers flowed into a glacier-dammed lake. Yet, the lama's keen interest and meticulous attention to the details of the landscape resonated with me. Despite lacking modern scientific training, his desire to comprehend the world mirrored my own.

I began to view science and mythology as two sides of the same coin. Historically, the distinction between these realms is a recent development; they were once intertwined.

Consider the story of Noah. Early natural philosophers' belief in a global flood influenced their interpretations of natural phenomena, even as they laid the groundwork for modern geology. Saint Augustine, a fourth-century bishop, cautioned against interpretations of the Bible that contradicted rational thought and nature study. He believed that the earth held truths; when he discovered seashells embedded in mountain rock, he interpreted them as evidence of a global flood. How else could marine life be trapped in mountaintops?

Nicolaus Steno, a 17th-century Danish natural philosopher, similarly used field observations to validate the biblical flood narrative. While examining a shark's head, he noted that its teeth resembled mysterious triangular objects in rocks—what we now recognize as fossilized shark teeth. To explain their presence in rock, Steno hypothesized that the earth formed in layers from a primordial sea, with the oldest layers at the bottom. This principle, now known as Steno's Law of Superposition, became foundational in geology. Steno argued that earth history included six stages, one of which was Noah's flood.

Over time, however, the connections between biblical accounts and geological science began to fray. Steno demonstrated that rocks could tell their own stories, thereby guiding and ultimately challenging religious doctrines. Successive generations of geologists and paleontologists established that the history of our planet, along with its flora and fauna, was far too intricate to conform neatly to a literal interpretation of scripture. By the time Darwin presented his revolutionary theories on evolution, the scientifically literate clergy had largely relinquished their belief in a global flood.

Now, geomythology is weaving together empirical evidence and symbolic narratives, uncovering factual kernels hidden within folklore. Humanity has always strived to make sense of the world and our place within it. For most of our history, oral traditions served as the primary means of preserving knowledge for future generations. In this regard, science can be viewed as an extension of folklore—a contemporary method of conveying the same stories, only with more robust data.

Great Flood Myths Across Cultures - The Similarities Will SHOCK You - This video delves into the various flood myths found in different cultures, highlighting their startling similarities and differences.

David R. Montgomery is a professor of geomorphology at the University of Washington and the author of The Rocks Don't Lie: A Geologist Investigates Noah's Flood and the forthcoming The Hidden Half of Nature: The Microbial Roots of Life and Health. In his free time, he plays guitar in the Seattle folk-rock band Big Dirt.