by Jack Nisbet
If, on the other hand, you are on a spacecraft orbiting Earth, you have a very wide field of view that extends for many hundreds of miles. That slows the cycle way down. When the craft passes through an aurora or straight over it, observers on board usually detect only a diffuse green color, as if they were inside a pale cloud. On the ISS, Phillips found that he had to look askance, toward Earth’s horizon, to see the bright coherent sheets. Even then, because of the great distance, they appeared to vibrate on a very slow period of activity. The color patterns would remain static for fifteen seconds or more before reconstituting themselves into some new form, then hold still for several more beats. “After a while, it wasn’t that big of a deal,” Phillips said. “With the aurora, it all depends on where you are.”
On the Ground
Whenever the northern limits of the space station’s orbit were above western Canada during daylight hours, John Phillips found himself in a perfect position to observe the geography of David Thompson’s western journeys among the tributaries of the upper Columbia River. These conditions occurred about every forty-eight hours. The astronaut began to time breaks in his required duties so that he could return to the single viewing port that looked directly down on the planet. From that vantage, just as the ISS was approaching its maximum northern latitude for a particular swing, Phillips soon located several of Thompson’s touchstone waterways—lured to them, really, by their luminous reflections.
As the ISS passed over southeastern British Columbia, Phillips spotted the two source lakes of the West’s great river, partially obscured by scudding clouds. Two days later, there he was again, leaning against his porthole, willing to coast through many more orbits in order to see the scene clearly. When his camera finally captured those twin lakes to his satisfaction, Phillips forwarded the image to me through the electric fluid of space.
Two centuries earlier, following the advice of Kootenai tribal elders, David Thompson built his first trade house west of the Rockies at the north end of those source lakes. In an attempt to absorb that landscape, I had walked myself footsore retracing his meanders along ancient Kootenai trails. But John Phillips’s photograph instantly provided me with a much deeper sense of context. Time and space seemed to move within it, providing a taste of the slow collision of one tectonic plate against another during the Late Cretaceous period, around seventy million years ago. I could suddenly see how the uplift of the Rocky Mountains related to the long narrow trench where the Columbia flowed north along the range’s western flank.
The photograph also captured the scars of more recent geologic events, after the great ice sheet of the Pleistocene epoch bulldozed along that trench from the north. As the ice retreated, it left behind a moraine of gravel that bulged just enough to nestle two puddles within the ditch, then pulled the water that leaked out of them north, in the direction of the receding glacier.
When I placed one of David Thompson’s maps next to Phillips’s image, all the same elements marched across the page, from the mountain ridges on each side of the nascent Columbia’s valley to the low divide that allowed the Kootenay River to rush south while its mother river began a much longer journey in the opposite direction. Thompson, with only tribal information and his own survey data, had created a bird’s-eye view that jibed remarkably well with the camera’s stark image.
John Phillips followed that first photo with several more, working his way south and west from the Columbia’s source lakes to track the course of David Thompson’s trade routes. What the astronaut saw from the space station was a landscape just below the southern edge of the great ice sheet—a terrain that at the end of the last glacial period was created and re-created by cycles of advancing ice thousands of feet thick. As those cycles waxed, ice-penned drainages backed up into huge lakes; as they waned, a succession of catastrophic meltdowns unleashed sudden torrential floods to rush across the Columbia Basin to the Pacific Ocean.
Such events seem to bend the elemental rules of physics in some of the same ways that David Thompson wrestled with during his winters in the north country. The air around us may light up with a glowing electrical charge. Fire can burble out of nowhere in the form of luminescent globes. The rocks of this Earth travel of their own accord, then explode or fly away. Ice sculpts solid ground, only to be followed by a rolling tsunami that transforms an entire landscape. The best any observer can hope for is to try to take it all in. There will be time later to figure out what was left behind and what has changed forever.
II
MELTDOWN
Keeping Fish Cool
Just north of downtown Spokane, Washington, a rough basalt mesa floats above the grid of city streets like an aerial island. Its heights provide stunning views of the Spokane and Little Spokane Rivers as they circle toward their confluence downstream. Farmed fields spot its interior, and tribal history tells of epic horse races across its flat top.
It was a searing summer day when I visited the base of the mesa with a group of Spokane tribal friends, descendants of the original residents of this area. On the edge of a quiet neighborhood, we parked near a stand of cattails that marked a small spring. A couple of younger members hopped out and dashed through a tangle of Douglas-firs, stumbling over rocks as they disappeared into the greenery. Before long, we could hear their voices oohing and aahing.
“What are we waiting for?” one of the elders asked, beckoning for me to help her out of the van.
Four of the ladies were over eighty, but they all negotiated a branchy trail that led to the base of an overgrown talus slope. We soon came in sight of an erect bus-sized boulder of pillow basalt poised higher on the hillside. “Like a finger,” I heard one of them say from behind me. “Pointing the way.”
Below the trail, in a hollow that had obviously been excavated and reworked by humans over the years, we found the youngsters holding out their palms in front of a crack in a craggy basalt face. The vent was only a couple of feet tall and half as wide, but even from a distance of several yards we could feel cool air wafting from its blackness. Nearby, a recent windstorm had partially toppled a gnarled, rockbound fir tree. From around its exposed roots, the same refreshing breeze poured out, continuous and strong. On such an uncomfortably hot day, it felt as though we had been carried to an entirely different place.
A search around the hollow revealed another crack that also breathed cool air. Noticeably caved in around the edges, this fissure looked as if it once might have been large enough for a person to walk inside. Craning forward, one of the ladies remarked that the subterranean air felt more than refreshing: it felt cold. A closer look revealed that ice rimed a few of the stones deeper inside.
The women, none of whom had ever been to this place, muttered with excitement. This must be one of the ice caves that they had been hearing about all their lives, but had never seen. Their Spokane ancestors, like many Plateau people, had stored fish and roots in caverns like these.
Newly arrived homesteaders trying to scratch out a living here in the early twentieth century used these cavities in exactly the same way. During the dog days of July 1929, a local newspaper ran a story headlined:
SPOKANE NATURAL WONDER
GIVES FREE ICE ON HOTTEST DAYS
OUTSIDE OF CAVES BAKES WHILE INSIDE IS ICEBOX
I had brought along a photocopy of the article for reference, and we studied the two grainy pictures that accompanied it. In the first, Mr. and Mrs. Edward Peterson posed in front of a narrow cave entrance, the opening of which looked like a tidier version of the vent beside which we were standing. The couple gazed at a thermometer that registered forty-five degrees, even as the rest of Spokane reported ninety-seven. Mrs. Peterson was quoted as saying that the cave extended about six feet into the hillside, and that she kept fruit inside it year-round.
By this time, the young explorers in the group had begun to work their way uphill along a pathway between the moss-covered talus slope and a windrow of loose basalt. The rest of us followed to an open area, where we gat
hered around a circular depression that was stuffed full with rotting lumber and rounds of old firewood. More cold air drifted from its depths.
This rubble-filled pit must be the old well described in the 1929 newspaper article, we decided. We compared the setting to the second photo, in which Edward Peterson squatted beside a rectangular cellar entrance. We soon spotted a handrail post and part of a step from Peterson’s neatly framed stairway among the debris. In the photo, Peterson had just ascended from the depths of the pit, where he had plucked a piece of ice from the rock floor to share with Patsy, his German shepherd. There were always several hundred pounds of ice on the bottom of the eight-foot well, Peterson explained. Ever since his parents homesteaded the place in 1899, the family had stored meat down there.
The newspaper reporter expressed bafflement at the source of the Petersons’ ice before wrapping up his article with the revelation that “Tule mats, well preserved, have been taken from this well.” That fact did not surprise the Spokane women, whose elders had told them how they would line their storage pits with tule mats, then arrange twined bags filled with salmon or roots between layers of sage leaves to discourage probing animals. In multifamily caches, distinct designs woven into each bag made for easy identification. Leaning over the edge of the pit, the women wondered whether any more of their ancestors’ tule mats or storage bags might still be down there, hidden in the darkness among the rocks—still perfectly flexible in the moist air, still carrying an odor of dried fish that no passage of time could extinguish.
At some point in the 1950s, residents in the neighborhood grew concerned about children playing among the dangerous rocks. They collapsed the cave openings and filled Peterson’s well with waste wood, but judging from the air that was caressing our faces, its bottom must still be covered with ice.
As we enjoyed our respite, one of the ladies recalled a cave that her uncle had told her about, somewhere near Kettle Falls. When he was about five years old, he had gone with his parents to the great salmon fishery there, a few years before the construction of Grand Coulee Dam. While everyone else was busy with the fish, he wandered off, tracing the edge of a stony outcrop. After a while he felt a breath of cool breeze seeping from a crack. Squeezing between two rocks, he found himself inside a cave. There he saw big icicles hanging down. He recalled touching the cold daggers and feeling the magic that made them grow. He broke one off and licked it: the first Popsicle he ever had.
“Just like here,” his niece said, leaning her head into the cool flow of air. “If we could crawl down into this hole, there would be Popsicles waiting for us.”
Many early newspapers and oral traditions throughout the Northwest contained reports about “ice caves,” “ice wells,” “ice tunnels,” “old ice,” and “blue ice” that mirrored the conditions of the odd vents in Spokane. In the days before electricity, such features were commonly used for refrigeration. In the town of Thompson Falls, Montana, on the Clark Fork River, early white settlers discovered that their basements often tapped into “cold air wells” that were perfect for preserving meat and produce. When a 1950s-era dam across Cabinet Gorge raised the water table upstream, it changed the dynamics of those drafty basements, and many old-timers were forced to purchase their first refrigerators. As recently as the 1980s, a road crew widening the state highway in the vicinity uncovered chunks of “ground ice” while removing rock from the base of surrounding outcrops. At the time, some reporters of the discovery wondered if the frozen blocks might be ancient ice left behind in the wake of the last glaciers.
Wondering whether all these accounts might be related, I contacted Idaho geologist Roy Breckinridge, who has spent much of his career thinking about ice. We visited the vents and well at the foot of the mesa in Spokane, and stumbled across talus slopes along the Clark Fork River. I asked him if the road crew could possibly have dug into a pocket of glacial ice. “I don’t think so,” he replied. “I think they exposed new ice.” He then patiently explained how each ice cave, shattered outcrop, and scree slide harbors its own peculiarities, depending upon the different sizes and shapes of the rocks and their placement in relation to each other.
In situations where air has enough room to flow through the spaces between the rocks, a sub-surface area can function much like a modern heat pump. Breezes can circulate in a cooling pattern and sink into a cavity that stores them in a passive sump. As air rises back through this natural system, it can combine with humidity to manufacture ice. All these configurations, for a geologist like Breckenridge, can be linked to earth-building processes of long ago. The question becomes which combination of natural forces arranged the rocks in just such a way to create these natural iceboxes. The answers to questions like this are rarely simple.
Imagining the Deluge
Roy Breckenridge is part of a long tradition of geologists, both amateur and professional, who have attempted to explain certain anomalies in the Inland Northwest landscape. In the 1920s, some of them focused on the extent of the Cordilleran Ice Sheet during the last ice age, and how that ice related to an array of features that stretch from western Montana across the Columbia Basin and beyond.
The Pleistocene story line at that time held that one lobe of the great ice sheet had pushed south at least as far as the Spokane River. A local geologist named Thomas Largé created a map that showed its cold tongue licking against the mesa where the Petersons lived. The power of that ice would have scraped and shattered rocks all along the mesa’s base; as the tongue retreated, it would have left behind erratic boulders and massive windrows of debris. Largé proposed that ripple marks and scoured volcanic flows throughout the vicinity were the result of meltwater pushed to high velocities under the weight of the retreating ice lobe. Many established geologists agreed with his ideas.
University of Chicago professor J Harlen Bretz, however, was not convinced of that theory and spent years combing the dry side of Washington State, carefully examining and reexamining the evidence. He came to believe that the ice stopped well north of Spokane, and that many of the distinctive features of the Inland Northwest were not the result of the slow advance and retreat of glaciers, but rather had been sculpted by a sudden massive flood. Harlen Bretz was not the first to entertain the notion of water as a major player in the drama. A century earlier, naturalist David Douglas and missionary Samuel Parker had both surmised that the Grand Coulee west of Spokane must have been carved by some dramatic flow. In 1899, geologist and forester J. B. Leiberg postulated that an ice plug had dammed the Clark Fork River near its mouth on Lake Pend Oreille. In 1910, another geologist, J. T. Pardee, reckoned that this ice dam must have attained a thickness of several thousand feet. He visualized how it would have impounded tributaries all the way upstream to Flathead Lake and the Bitterroot Valley, creating a vast body of water that he called Glacial Lake Missoula.
Pardee’s work helped Harlen Bretz to envision a credible mechanism for a flood of biblical scale, and in 1923, Bretz published the first of more than a dozen technical papers detailing his ideas. He theorized that as the climate warmed at the end of the Pleistocene, the ice dam had come apart. Its sudden failure allowed the totality of the lake’s water to flush the ice from Lake Pend Oreille’s basin, then fan out with devastating speed, crashing through the Spokane countryside and across the Columbia Basin. The deluge backed up behind the constriction of Wallula Gap before tearing through the Columbia River Gorge with renewed force. This single jet of floodwater split again at the Willamette Valley, forking to find separate ways to the sea.
Few of Harlen Bretz’s fellow geologists bought into the notion of the cataclysmic event that he called the Spokane or Lake Missoula Flood, and decades passed before the theory gained wide acceptance. But by the early twenty-first century, the saga of the Ice Age floods stood as a defining chapter in the region’s history. To gain any sense of the Inland Northwest landscape, you have to comprehend these immense forces at work. You must try and picture how the dam failed within a matter of hours, and
how the whole event played out over the course of a few days. You have to realize that, after the first apocalyptic deluge, global weather cycled back toward the cold. Within a few decades, a lobe of the continental glacier again crept south to form another thick dam across the Clark Fork delta and Lake Pend Oreille. A new Glacial Lake Missoula filled, lapping at levels clearly visible today on bare hillsides. Another warming trend and catastrophic ice failure followed, releasing another torrent to pound its way to the sea. You have to imagine this happening dozens of times as the climate wobbled toward the warmth of the Holocene epoch. Today we have accepted the spectacle of these floods washing over our earth as common knowledge, and we marvel that it took geologists so long to figure it out.
Inside the Icebox
Even though the basics of this story have been available for almost a century, the devil, as Roy Breckenridge continually points out, is in the details. He and his colleagues study the events that took place around Lake Pend Oreille and the lower Clark Fork River at the end of the Pleistocene, trying to figure out how the Cordilleran Ice Sheet formed a wall that was tall enough and strong enough to back up an enormous Glacial Lake Missoula. They want to know how such a massive dam could have failed so catastrophically, and exactly what happened when three thousand square miles of deep water roared away. They are curious as to how the ice then re-formed to replay the same scene, with subtle variations, many times over.
Sometimes scaling down to the finer points of the story, all the way to refrigerated basements and cold air wells, can provide insight. And sometimes you have to consider the much grander progression of deep time.
