The Rocks Don't Lie: A Geologist Investigates Noah's Flood (29 page)

After European geologists dismissed a central role for a catastrophic flood in earth history, the idea became geological heresy. Although J Harlen Bretz uncovered evidence of giant floods in eastern Washington in the 1920s, it took most of the twentieth century for other geologists to believe him. Geologists had so thoroughly denied the existence of great floods that they could not believe it when somebody actually found evidence for one.

A controversial figure throughout his career, Bretz won no awards until long after he retired and his most influential and vociferous critics died. There was no volume written by distinguished colleagues to honor his career. He was an outsider, a heretic dismissed by the scientific establishment. A classic field geologist, Bretz figured out the story of the region’s giant glacial floods, seeing what others at first could not and then would not see to sort out the pieces of a landscape-scale jigsaw puzzle.

Bretz became unpopular when he questioned orthodox uniformitarianism, Lyell’s dictate that the processes of today are the same as those of the past. Fresh out of graduate school and perhaps not knowing any better, Bretz identified compelling evidence for a gigantic flood. A reluctant heretic, he insisted on valuing field evidence above theory, piecing together the story of how a raging wall of water hundreds of feet high roared across eastern Washington, carving deep channels before cascading down the Columbia River gorge as a wall of water high enough to turn Oregon’s Willamette Valley into a vast backwater lake. This time it was the scientific community that refused to see the evidence. Vying to be the first to prove himself wrong, Bretz kept digging. But as he kept finding more evidence of a really big flood, the geological establishment kept coming up with ways of explaining it away.

Bretz taught in his native Michigan before heading west to teach high school in Seattle. A field enthusiast, he spent his weekends and summers studying the geology around Puget Sound as well as glaciers in the nearby Cascade Range. Eventually he enrolled at the University of Chicago, graduating
summa cum laude
with a PhD based on western Washington’s glacial geology in 1913. After spending a year on the faculty of the University of Washington, where his colleagues did not appreciate his enthusiasm for fieldwork, he accepted an invitation to return to Chicago, where he taught until he retired in 1947. Dedicated to teaching geology in the field and enamored with the landscapes of eastern Washington, he started bringing summer classes to the Columbia River gorge.

There Bretz found exotic granite boulders perched on basalt cliffs hundreds of feet above the highest recorded river level. Glaciers could not have carried these boulders to these elevations. Geological evidence had already proven glaciers had never reached the gorge. His colleagues thought this part of the Cascade Range lay submerged beneath the Pacific Ocean when the boulders arrived, carried by floating ice. Finding no evidence of marine fossils or ancient beaches, however, Bretz concluded the boulders must have been deposited by fresh water. But what could have generated such an enormous flood?

Each summer he returned to explore farther upstream. After several summers canvassing the gorge, he shifted north to the scablands. Exploring the strange topography of the area, Bretz came across dry waterfalls and potholes hundreds of feet above the modern river. Gigantic gravel bars deposited within coulees (dry valleys) implied deep, fast-flowing water. Scour lines that crossed over drainage divides showed that flowing water had overtopped ridgelines and spilled into adjacent valleys. Streamlined hills rose like islands sticking up more than a hundred feet above the scoured out channelways. Bretz realized the chaotic landscape had been carved by enormous floods that chewed deep channels through hundreds of feet of solid basalt. Here, right before his eyes, was the unthinkable.

Ever since Reverend Samuel Parker first described the Grand Coulee as a former channel of the Columbia River in 1838, explorers and geologists agreed that a glacially diverted river that ran across the plateau gradually carved the scablands before returning to its normal valley. But Bretz identified how these now streamless canyons defined a drainage pattern unlike any formed by normal rivers. Here was an interconnected complex of enormous channels that branched out only to reconnect downstream. Such a network could only form if water had filled valleys to overflowing and spilled a great flood over their drainage divides. He called this enormous flood the Spokane Flood. But what was the source of all that water?

Bretz first presented his thoughts on the channeled scablands to the Geological Society of America in 1923. Focused on describing his field observations, he was careful not to invoke the taboo of referring to a monstrous flood. He attributed the flows that carved the valleys to an ice dam across the Columbia River that forced water to spill out across the scablands. Over successive summers Bretz became increasingly confident that the scablands were not just the gradually produced work of a diverted river.

He recognized that 100-foot-high piles of gravel on the canyon floors were built by even deeper flows and that the hanging valleys that drained over dry waterfalls were not the product of normal stream erosion. These features were carved by a process that shut off before forming a smoothly integrated channel network. Troubled by how the field evidence pointed to a giant flood spilling over from the Columbia River to scour the scablands, he found good reasons to reject all other possibilities.

Tracing the evidence downstream through the Columbia River Gorge, Bretz found that his flood deposited an enormous delta around Portland, Oregon, backing up flow into the Willamette Valley. Taking advantage of locations where the flow constricted, he calculated a peak discharge so large he even doubted it himself—over sixty-six million cubic feet per second. Field evidence kept pointing to a really big flood.

Bretz could think of only two forces that could have produced his troubling flood. Either a very rapid and short-lived warming of the climate or a volcanic eruption beneath an ice cap. Neither provided a satisfying explanation. He had a flood without a cause.

His colleagues were as perplexed as he was. The battle over how long it took rivers to carve valleys had already been won. Even Bretz acknowledged the challenge that his catastrophic flood presented to conventional thinking. Yet, the giant gravel bars in the now dry canyons mirrored the form of ripples on the bed of a sandy river—only they were much, much larger. Some tear-dropped shaped bedrock hills were still capped with loose silt, showing that the flow that streamlined them did not overtop them. One could map the extent of the flood. Somewhat reluctantly, Bretz concluded that catastrophic flooding provided the best explanation for his field observations.

In January 1927, Bretz was invited to present his findings to the Geological Society of Washington, DC. It made no difference that he systematically outlined his arguments: dry canyons carved hundreds of feet into hard basalt, hundreds of dry waterfalls some two to three miles across; the stripping off of several hundred feet of silt and soil over large areas; and interconnected overflow channels that crossed drainage divides. It was an ambush. Representatives of the Geological Society of America and the U.S. Geological Survey also attended the meeting. One by one they rose to crucify the heretic’s description of the flood.

The first critic cautiously warned about the difficulty in finding a source that could release so much water so fast. Surely, he asserted, many small floods gradually carved the scablands. The next critic doubted that so much hard basalt could be carved out in a brief flood, no matter how deep the flow. Another argued that a diverted Columbia River swollen by glacial meltwater could have slowly incised the scabland channels. This defender of geologic sanity was so eager to dismiss the idea of a catastrophic flood that he argued that the elevations of spillways originally cut at different altitudes were now identical due to subsequent earth movements fortuitously aligning them at precisely the same height. Although no one questioned his observations, every speaker challenged Bretz’s interpretation, pointing out that he had no way to explain how to get so much water so fast. Although this was a lopsided debate, it was deeply rooted in a long tradition of geologists sparring and arguing over how to interpret observations. What everyone, including Bretz, could agree on was that further fieldwork was needed to explain the channeled scablands.

One of those attending the DC ambush was Joe Pardee, a Geological Survey geologist. Two years before, Pardee wondered whether the scablands could have been carved by catastrophic drainage from Lake Missoula, an ancient glacier-dammed lake he had discovered evidence for in western Montana back in 1910. He wrote to Bretz suggesting this as a possible source for his Spokane Flood. Bretz ignored him. An account of the DC meeting relates how during the discussion Pardee confided to a colleague that he knew
the origin of Bretz’s flood. But with a career and a reputation to maintain he stayed quiet, unwilling to upset his boss, who had been the first speaker to challenge Bretz.

Map of floods from ice-dammed glacial Lake Missoula (black) showing branching structure of flood through the Channeled Scablands and the extent of backwater up into the Willamette Valley (gray).

The next summer, Bretz went back to the field and found deposits formed by water flowing backwards up Columbia River tributaries. Along the Snake River he traced backwater deposits upstream beyond Lewiston, Idaho. Only a huge flood could have sent deep water surging back up into tributaries. Grudgingly taking Pardee’s hint, Bretz settled on drainage from Lake Missoula as the source of his flood.

Nobody else believed him. The remoteness of the scablands and the difficulty of traveling there during the Depression fostered skepticism among colleagues back east, few of whom had been out west to see the area for themselves.

Geologists kept arguing about the scablands and attacking the heretic’s flood. One colleague dusted off Bretz’s original idea of a flood produced by water backing up from a Columbia River ice jam. Others invoked glacial erosion, ignoring the fact that the scablands lay south of the well-documented extent of glaciers. Or maybe ancient rivers slowly cut down through normal river erosion, although this could not account for the giant potholes. One prominent critic carefully described—and then ignored—areas of ten-foot-high undulating ridges running across the trend of the valley they occurred in, features Bretz later identified as incontrovertible evidence of catastrophic flooding.

The tide turned at the 1940 Seattle meeting of the American Association for the Advancement of Science. In a session on the glacial geology of the Pacific Northwest crowded with megaflood skeptics, Joe Pardee described evidence for giant ripple marks on the bed of the glacial-age Lake Missoula. Pardee recognized that the fifty-foot-high ripples on the lakebed were formed by fast-flowing currents rather than the sluggish bottom water of an impounded lake. Only sudden failure of the glacial dam could have released the two-thousand-foot-deep lake. Pardee did not need to point out that here was a logical source for Bretz’s flood: the catastrophic release of six hundred cubic miles of water through a narrow gap would sweep away everything in its path.

In 1952 Bretz returned for a last summer of fieldwork in the scablands. Nearly seventy years old, he wanted to see evidence uncovered by the Bureau of Reclamation’s Columbia Basin project. He was delighted to find their excavations showed that the hills he interpreted as hundred-foot-high gravel bars were indeed formed by deep, fast-flowing water.

Examining the bureau’s aerial photography, Bretz found the smoking gun that clinched his story. The bird’s-eye view revealed the rugged rise and fall of the topography he recalled scrambling over decades before to be giant ripples like those hundreds of miles upstream at the outlet to Lake Missoula. Hidden beneath the sagebrush, the field of megaripples was strikingly obvious from the air. There was “no other explanation for their rhythmic patterns than that of bedform development by amazingly deep, swift flood water.”
¹
Bretz had been right all along.

It had taken decades, but he finally had the evidence to convince skeptical colleagues. In August 1965, an international delegation of geologists traveled from Lake Missoula down through the scablands to see the evidence firsthand. Bretz was no longer able to travel, so at the end of the trip the delegation sent him a congratulatory telegram that ended with “We are now all catastrophists.”
²
It took a changing of the generational guard for geologists to accept the heretic’s flood.

In the summer of 1976, just before his ninety-fourth birthday, NASA scientists invoked Bretz’s careful fieldwork on understanding features diagnostic of catastrophic flooding to explain streamlined hillslopes and giant channels in images returned by the Viking spacecraft orbiting Mars. Half a century after government scientists gathered to denounce his radical theory of erosion by catastrophic flooding, NASA was hailing his studies of the channeled scablands as the key to understanding enigmatic Martian landforms.