by Bill Bryson
Once it is in place, the idea is that three people--Christiansen in Menlo Park, California, Professor Robert B. Smith at the University of Utah, and Doss in the park--would assess the degree of danger of any potential cataclysm and advise the park superintendent. The superintendent would take the decision whether to evacuate the park. As for surrounding areas, there are no plans. If Yellowstone were going to blow in a really big way, you would be on your own once you left the park gates.
Of course it may be tens of thousands of years before that day comes. Doss thinks such a day may not come at all. "Just because there was a pattern in the past doesn't mean that it still holds true," he says. "There is some evidence to suggest that the pattern may be a series of catastrophic explosions, then a long period of quiet. We may be in that now. The evidence now is that most of the magma chamber is cooling and crystallizing. It is releasing its volatiles; you need to trap volatiles for an explosive eruption."
In the meantime there are plenty of other dangers in and around Yellowstone, as was made devastatingly evident on the night of August 17, 1959, at a place called Hebgen Lake just outside the park. At twenty minutes to midnight on that date, Hebgen Lake suffered a catastrophic quake. It was magnitude 7.5, not vast as earthquakes go, but so abrupt and wrenching that it collapsed an entire mountainside. It was the height of the summer season, though fortunately not so many people went to Yellowstone in those days as now. Eighty million tons of rock, moving at more than one hundred miles an hour, just fell off the mountain, traveling with such force and momentum that the leading edge of the landslide ran four hundred feet up a mountain on the other side of the valley. Along its path lay part of the Rock Creek Campground. Twenty-eight campers were killed, nineteen of them buried too deep ever to be found again. The devastation was swift but heartbreakingly fickle. Three brothers, sleeping in one tent, were spared. Their parents, sleeping in another tent beside them, were swept away and never seen again.
"A big earthquake--and I mean big--will happen sometime," Doss told me. "You can count on that. This is a big fault zone for earthquakes."
Despite the Hebgen Lake quake and the other known risks, Yellowstone didn't get permanent seismometers until the 1970s.
If you needed a way to appreciate the grandeur and inexorable nature of geologic processes, you could do worse than to consider the Tetons, the sumptuously jagged range that stands just to the south of Yellowstone National Park. Nine million years ago, the Tetons didn't exist. The land around Jackson Hole was just a high grassy plain. But then a forty-mile-long fault opened within the Earth, and since then, about once every nine hundred years, the Tetons experience a really big earthquake, enough to jerk them another six feet higher. It is these repeated jerks over eons that have raised them to their present majestic heights of seven thousand feet.
That nine hundred years is an average--and a somewhat misleading one. According to Robert B. Smith and Lee J. Siegel in Windows into the Earth , a geological history of the region, the last major Teton quake was somewhere between about five and seven thousand years ago. The Tetons, in short, are about the most overdue earthquake zone on the planet.
Hydrothermal explosions are also a significant risk. They can happen anytime, pretty much anywhere, and without any predictability. "You know, by design we funnel visitors into thermal basins," Doss told me after we had watched Old Faithful blow. "It's what they come to see. Did you know there are more geysers and hot springs at Yellowstone than in all the rest of the world combined?"
"I didn't know that."
He nodded. "Ten thousand of them, and nobody knows when a new vent might open." We drove to a place called Duck Lake, a body of water a couple of hundred yards across. "It looks completely innocuous," he said. "It's just a big pond. But this big hole didn't used to be here. At some time in the last fifteen thousand years this blew in a really big way. You'd have had several tens of millions of tons of earth and rock and superheated water blowing out at hypersonic speeds. You can imagine what it would be like if this happened under, say, the parking lot at Old Faithful or one of the visitors' centers." He made an unhappy face.
"Would there be any warning?"
"Probably not. The last significant explosion in the park was at a place called Pork Chop Geyser in 1989. That left a crater about five meters across--not huge by any means, but big enough if you happened to be standing there at the time. Fortunately, nobody was around so nobody was hurt, but that happened without warning. In the very ancient past there have been explosions that have made holes a mile across. And nobody can tell you where or when that might happen again. You just have to hope that you're not standing there when it does."
Big rockfalls are also a danger. There was a big one at Gardiner Canyon in 1999, but again fortunately no one was hurt. Late in the afternoon, Doss and I stopped at a place where there was a rock overhang poised above a busy park road. Cracks were clearly visible. "It could go at any time," Doss said thoughtfully.
"You're kidding," I said. There wasn't a moment when there weren't two cars passing beneath it, all filled with, in the most literal sense, happy campers.
"Oh, it's not likely," he added. "I'm just saying it could . Equally it could stay like that for decades. There's just no telling. People have to accept that there is risk in coming here. That's all there is to it."
As we walked back to his vehicle to head back to Mammoth Hot Springs, Doss added: "But the thing is, most of the time bad things don't happen. Rocks don't fall. Earthquakes don't occur. New vents don't suddenly open up. For all the instability, it's mostly remarkably and amazingly tranquil."
"Like Earth itself," I remarked.
"Precisely," he agreed.
The risks at Yellowstone apply to park employees as much as to visitors. Doss got a horrific sense of that in his first week on the job five years earlier. Late one night, three young summer employees engaged in an illicit activity known as "hot-potting"--swimming or basking in warm pools. Though the park, for obvious reasons, doesn't publicize it, not all the pools in Yellowstone are dangerously hot. Some are extremely agreeable to lie in, and it was the habit of some of the summer employees to have a dip late at night even though it was against the rules to do so. Foolishly the threesome had failed to take a flashlight, which was extremely dangerous because much of the soil around the warm pools is crusty and thin and one can easily fall through into a scalding vent below. In any case, as they made their way back to their dorm, they came across a stream that they had had to leap over earlier. They backed up a few paces, linked arms and, on the count of three, took a running jump. In fact, it wasn't the stream at all. It was a boiling pool. In the dark they had lost their bearings. None of the three survived.
I thought about this the next morning as I made a brief call, on my way out of the park, at a place called Emerald Pool, in the Upper Geyser Basin. Doss hadn't had time to take me there the day before, but I thought I ought at least to have a look at it, for Emerald Pool is a historic site.
In 1965, a husband-and-wife team of biologists named Thomas and Louise Brock, while on a summer study trip, had done a crazy thing. They had scooped up some of the yellowy-brown scum that rimmed the pool and examined it for life. To their, and eventually the wider world's, deep surprise, it was full of living microbes. They had found the world's first extremophiles--organisms that could live in water that had previously been assumed to be much too hot or acid or choked with sulfur to bear life. Emerald Pool, remarkably, was all these things, yet at least two types of living things, Sulpholobus acidocaldarius and Thermophilus aquaticus as they became known, found it congenial. It had always been supposed that nothing could survive above temperatures of 50°C (122°F), but here were organisms basking in rank, acidic waters nearly twice that hot.
For almost twenty years, one of the Brocks' two new bacteria, Thermophilus aquaticus , remained a laboratory curiosity until a scientist in California named Kary B. Mullis realized that heat-resistant enzymes within it could be used to create a bit o
f chemical wizardry known as a polymerase chain reaction, which allows scientists to generate lots of DNA from very small amounts--as little as a single molecule in ideal conditions. It's a kind of genetic photocopying, and it became the basis for all subsequent genetic science, from academic studies to police forensic work. It won Mullis the Nobel Prize in chemistry in 1993.
Meanwhile, scientists were finding even hardier microbes, now known as hyperthermophiles, which demand temperatures of 80°C (176°F) or more. The warmest organism found so far, according to Frances Ashcroft in Life at the Extremes , is Pyrolobus fumarii , which dwells in the walls of ocean vents where the temperature can reach 113°C (235.4°F). The upper limit for life is thought to be about 120°C (248°F), though no one actually knows. At all events, the Brocks' findings completely changed our perception of the living world. As NASA scientist Jay Bergstralh has put it: "Wherever we go on Earth--even into what's seemed like the most hostile possible environments for life--as long as there is liquid water and some source of chemical energy we find life."
Life, it turns out, is infinitely more clever and adaptable than anyone had ever supposed. This is a very good thing, for as we are about to see, we live in a world that doesn't altogether seem to want us here.
PART V LIFE ITSELF
16 LONELY PLANET
IT ISN'T EASY being an organism. In the whole universe, as far as we yet know, there is only one place, an inconspicuous outpost of the Milky Way called Earth, that will sustain you, and even it can be pretty grudging.
From the bottom of the deepest ocean trench to the top of the highest mountain, the zone that covers nearly the whole of known life, is only something over a dozen miles--not much when set against the roominess of the cosmos at large.
For humans it is even worse because we happen to belong to the portion of living things that took the rash but venturesome decision 400 million years ago to crawl out of the seas and become land based and oxygen breathing. In consequence, no less than 99.5 percent of the world's habitable space by volume, according to one estimate, is fundamentally--in practical terms completely--off-limits to us.
It isn't simply that we can't breathe in water, but that we couldn't bear the pressures. Because water is about 1,300 times heavier than air, pressures rise swiftly as you descend--by the equivalent of one atmosphere for every ten meters (thirty-three feet) of depth. On land, if you rose to the top of a five-hundred-foot eminence--Cologne Cathedral or the Washington Monument, say--the change in pressure would be so slight as to be indiscernible. At the same depth underwater, however, your veins would collapse and your lungs would compress to the approximate dimensions of a Coke can. Amazingly, people do voluntarily dive to such depths, without breathing apparatus, for the fun of it in a sport known as free diving. Apparently the experience of having your internal organs rudely deformed is thought exhilarating (though not presumably as exhilarating as having them return to their former dimensions upon resurfacing). To reach such depths, however, divers must be dragged down, and quite briskly, by weights. Without assistance, the deepest anyone has gone and lived to talk about it afterward was an Italian named Umberto Pelizzari, who in 1992 dove to a depth of 236 feet, lingered for a nanosecond, and then shot back to the surface. In terrestrial terms, 236 feet is just slightly over the length of one New York City block. So even in our most exuberant stunts we can hardly claim to be masters of the abyss.
Other organisms do of course manage to deal with the pressures at depth, though quite how some of them do so is a mystery. The deepest point in the ocean is the Mariana Trench in the Pacific. There, some seven miles down, the pressures rise to over sixteen thousand pounds per square inch. We have managed once, briefly, to send humans to that depth in a sturdy diving vessel, yet it is home to colonies of amphipods, a type of crustacean similar to shrimp but transparent, which survive without any protection at all. Most oceans are of course much shallower, but even at the average ocean depth of two and a half miles the pressure is equivalent to being squashed beneath a stack of fourteen loaded cement trucks.
Nearly everyone, including the authors of some popular books on oceanography, assumes that the human body would crumple under the immense pressures of the deep ocean. In fact, this appears not to be the case. Because we are made largely of water ourselves, and water is "virtually incompressible," in the words of Frances Ashcroft of Oxford University, "the body remains at the same pressure as the surrounding water, and is not crushed at depth." It is the gases inside your body, particularly in the lungs, that cause the trouble. These do compress, though at what point the compression becomes fatal is not known. Until quite recently it was thought that anyone diving to one hundred meters or so would die painfully as his or her lungs imploded or chest wall collapsed, but the free divers have repeatedly proved otherwise. It appears, according to Ashcroft, that "humans may be more like whales and dolphins than had been expected."
Plenty else can go wrong, however. In the days of diving suits--the sort that were connected to the surface by long hoses--divers sometimes experienced a dreaded phenomenon known as "the squeeze." This occurred when the surface pumps failed, leading to a catastrophic loss of pressure in the suit. The air would leave the suit with such violence that the hapless diver would be, all too literally, sucked up into the helmet and hosepipe. When hauled to the surface, "all that is left in the suit are his bones and some rags of flesh," the biologist J. B. S. Haldane wrote in 1947, adding for the benefit of doubters, "This has happened."
(Incidentally, the original diving helmet, designed in 1823 by an Englishman named Charles Deane, was intended not for diving but for fire-fighting. It was called a "smoke helmet," but being made of metal it was hot and cumbersome and, as Deane soon discovered, firefighters had no particular eagerness to enter burning structures in any form of attire, but most especially not in something that heated up like a kettle and made them clumsy into the bargain. In an attempt to save his investment, Deane tried it underwater and found it was ideal for salvage work.)
The real terror of the deep, however, is the bends--not so much because they are unpleasant, though of course they are, as because they are so much more likely. The air we breathe is 80 percent nitrogen. Put the human body under pressure, and that nitrogen is transformed into tiny bubbles that migrate into the blood and tissues. If the pressure is changed too rapidly--as with a too-quick ascent by a diver--the bubbles trapped within the body will begin to fizz in exactly the manner of a freshly opened bottle of champagne, clogging tiny blood vessels, depriving cells of oxygen, and causing pain so excruciating that sufferers are prone to bend double in agony--hence "the bends."
The bends have been an occupational hazard for sponge and pearl divers since time immemorial but didn't attract much attention in the Western world until the nineteenth century, and then it was among people who didn't get wet at all (or at least not very wet and not generally much above the ankles). They were caisson workers. Caissons were enclosed dry chambers built on riverbeds to facilitate the construction of bridge piers. They were filled with compressed air, and often when the workers emerged after an extended period of working under this artificial pressure they experienced mild symptoms like tingling or itchy skin. But an unpredictable few felt more insistent pain in the joints and occasionally collapsed in agony, sometimes never to get up again.
It was all most puzzling. Sometimes workers would go to bed feeling fine, but wake up paralyzed. Sometimes they wouldn't wake up at all. Ashcroft relates a story concerning the directors of a new tunnel under the Thames who held a celebratory banquet as the tunnel neared completion. To their consternation their champagne failed to fizz when uncorked in the compressed air of the tunnel. However, when at length they emerged into the fresh air of a London evening, the bubbles sprang instantly to fizziness, memorably enlivening the digestive process.
Apart from avoiding high-pressure environments altogether, only two strategies are reliably successful against the bends. The first is to suffer only a very short
exposure to the changes in pressure. That is why the free divers I mentioned earlier can descend to depths of five hundred feet without ill effect. They don't stay under long enough for the nitrogen in their system to dissolve into their tissues. The other solution is to ascend by careful stages. This allows the little bubbles of nitrogen to dissipate harmlessly.
A great deal of what we know about surviving at extremes is owed to the extraordinary father-and-son team of John Scott and J. B. S. Haldane. Even by the demanding standards of British intellectuals, the Haldanes were outstandingly eccentric. The senior Haldane was born in 1860 to an aristocratic Scottish family (his brother was Viscount Haldane) but spent most of his career in comparative modesty as a professor of physiology at Oxford. He was famously absent-minded. Once after his wife had sent him upstairs to change for a dinner party he failed to return and was discovered asleep in bed in his pajamas. When roused, Haldane explained that he had found himself disrobing and assumed it was bedtime. His idea of a vacation was to travel to Cornwall to study hookworm in miners. Aldous Huxley, the novelist grandson of T. H. Huxley, who lived with the Haldanes for a time, parodied him, a touch mercilessly, as the scientist Edward Tantamount in the novel Point Counter Point .
Haldane's gift to diving was to work out the rest intervals necessary to manage an ascent from the depths without getting the bends, but his interests ranged across the whole of physiology, from studying altitude sickness in climbers to the problems of heatstroke in desert regions. He had a particular interest in the effects of toxic gases on the human body. To understand more exactly how carbon monoxide leaks killed miners, he methodically poisoned himself, carefully taking and measuring his own blood samples the while. He quit only when he was on the verge of losing all muscle control and his blood saturation level had reached 56 percent--a level, as Trevor Norton notes in his entertaining history of diving, Stars Beneath the Sea , only fractionally removed from nearly certain lethality.