by John Dvorak
Muir was unconvinced and responded to Whitney in his first published work, “Yosemite Glaciers,” an essay that appeared on December 5, 1871, in the New York Tribune, the city’s most widely read newspaper. He laid out the argument that “the Great Valley itself, together with all its domes and walls, was brought forth and fashioned by a grand combination of glaciers.”
One wonders what direction the earthquake-versus-glacier debate might have taken if a major earthquake had not occurred beneath the Sierra Nevada Mountains less than four months later.
Muir was asleep in a small cabin he had built near Sentinel Rock on the valley floor when, during the early morning hours of March 26, 1872, he was awakened by shaking. “Though I had never before enjoyed a storm of this sort,” he would later write, “the strange, wild thrilling motion and rumbling could not be mistaken.”
He ran outside into a clear, moonlit night, feeling “both glad and frightened.” “A noble earthquake,” he shouted. He was sure he was going to learn something.
The shaking was so violent and varied, one pulse quickly succeeding another, that he had difficulty walking and had to balance himself as if on a ship in big waves. He could hear rocks from the steep walls descending all around him, and so he took shelter as best he could behind a large yellow pine. The shaking lasted almost two minutes. Muir watched as the face of Eagle Rock gave way and fell into the valley with a tremendous roar. But even before the great boulders had settled in place, he was on top of them, listening as they gradually quieted.
After sunrise, he walked about to see what other changes had occurred. He saw some people who were wintering in the valley assembled in front of a small hotel. He joined them and listened as they compared notes. They talked about the earthquake and whether they should leave the valley. A muffled rumbling similar to thunder was heard, followed by a shock milder than the initial one.
Muir recognized one of the people to be a shopkeeper in the valley who Muir knew was a firm believer in the cataclysmic origin of Yosemite Valley. Muir jokingly remarked that Whitney’s “wild tumbled-down-and-engulfment hypothesis” might soon be given a test. Just then came another shock, and the shopkeeper became solemn. Muir now tried to cheer him up by telling him that the earthquake had just been Mother Earth “trotting us on her knee to amuse us and make us good.” The man was not amused. He and the others quickly gathered their things and left the valley. A month later the man returned, but when another tremor happened the same day in a shocking coincidence, Muir watched as the shopkeeper was sent flying again.
Muir remained at Yosemite after the large earthquake and its aftershocks, intrigued by what might happen next. He filled a bucket with water and placed it on a table and watched it for hours, noticing that the surface of the water would dimple every time Mother Earth sent another slight tap from far below.
Whitney was in San Francisco during the earthquake and slept through the event, as did almost everyone else in the city. Thomas Tennant, a self-appointed weather observer who had been in California since the Gold Rush, was one of the few in the Bay Area who felt the shaking, recording it as “a light earthquake.”
By sunrise, telegraph wires were buzzing with reports. The earthquake had been felt from Shasta to San Diego and as far east as Eureka, Nevada. A quick study of the reports showed that the most severe shaking had not been in Yosemite Valley, but along the east side of the Sierra Nevada Mountains in Owens Valley at a small mining community known as Lone Pine.
By coincidence, Whitney was planning to work later that spring in Owens Valley, and so he passed through Lone Pine on May 21. He confirmed what had been reported in the newspapers: Almost every one of the 59 buildings of Lone Pine, mostly adobe houses, had collapsed. And 27 people, nearly 10% of the population, had been killed.
In an article he would write for Overland Monthly, a California-based magazine, he described entering Lone Pine as being “in the midst of a scene of ruin and disaster.” He surveyed the damage, which was still quite evident. At some point he went to the north edge of town, where, even today, there is a poignant reminder of the sorrow an earthquake can bring. At the top of a sandy hill just west of State Highway 395 is a mass grave where 16 of the earthquake victims were buried. Today it is surrounded by a weathered wooden picket fence. The plot is so small that some of the bodies must have been laid atop others. At first thought, one is puzzled why so small an area was used as a grave site; then one remembers that all 16 had died at the same instant, and this was the only way, in this treeless expanse, to bury them quickly, something that was of prime importance in an era when disease spread rampantly.
From the grave site, one can see something else of curiosity related to the earthquake. To the southwest, in the direction of the Sierra Nevada Mountains, at the base of a range of low hills that, because of their striking appearance, has been the filming location for many popular Hollywood movies (including How the West Was Won, Star Trek Generations, and Transformers: Revenge of the Fallen, as well as the opening scene of Iron Man) is a line that looks like a frozen wave of upturned rocks. Close inspection shows that is exactly what it is.
It is what geologists call a scarp, a step on the ground surface where one side of a fault has moved vertically with respect to the other, and it is as high as 20 feet, running for more than 40 miles parallel with the valley and the mountains. Along its face are huge boulders. People in Lone Pine told Whitney that the scarp formed during the earthquake, and he agreed.
The scarp was not the only feature that formed during the earthquake. There were also long cracks and fissures that Whitney found elsewhere on the valley floor. Following convention, he explained these and the 40-mile-long scarp as secondary effects of the earthquake—that is, they were the result of the violent shaking that had caused the loose ground to settle more in some places than others. If he had paused, he might have realized that there was a fundamental difference between the cracks and fissures and the rock-faced scarp—one that another man would clearly see and, thereby, change the whole perception of the cause and nature of earthquakes—but Whitney was not attuned to make such a distinction.
If he had been, he probably would have realized that a cataclysmic earthquake could not have formed Yosemite Valley, although after what had happened in 1872, he could be forgiven for thinking so.** But for him to have seen a distinction between what created the valley and an actual earthquake would have required a radical change in thinking. And to achieve that change, one had to know exactly what caused earthquakes, something Whitney himself still did not know. At the time, conventional wisdom held that such sudden and, at times, strong shakings were caused by volcanic explosions occurring inside the Earth.
In 1750, England, seldom disturbed by earthquakes, was shaken twice. The first occurred just after noon on February 8 and caused so much alarm that the barristers at Westminster thought the stone hall was falling down. Exactly a month later, on March 8 at half past five in the morning, another tremor struck, throwing people out of their beds and causing the chime hammers to strike bells in church steeples. The next day, John Wesley, renowned minister and founder of Methodism, gave his Sermon 129, The Causes and Cure of Earthquakes. In that sermon, he proclaimed, “God is himself the Author, and sin is the moral cause.” The only cure, of course, was repentance.
Five years later, on November 1, 1755, an earthquake devastated Lisbon, Portugal. Tens of thousands died, most by drowning due to an earthquake-produced tsunami. Shaking was felt from Finland to North Africa and as far west as the Azores Islands. Then, 17 days later, just as news of the Lisbon disaster reached Boston, New England was struck by the strongest earthquake yet to hit that region.
The New England earthquake was felt from Nova Scotia to South Carolina. The most intense shaking was around Boston, where, though no one died, many brick walls and chimneys fell. John Adams, then 20 years old, was at his father’s house in Braintree. The next day, presumably inspired by the
earthquake, he started his famous diary, which would continue for more than 50 volumes and include details about the revolution and the difficulties of forming a constitutional government. The first entry, however, is about the earthquake, which caused his father’s house “to rock and reel and crack as if it would fall in ruin around us.”
John Winthrop, a professor of mathematics and philosophy at Harvard College, concerned that local clergy would replay Wesley’s sermons, on November 26 gave “A Lecture on Earthquakes: Read in the Chapel of Harvard College.” His lecture would mark a turning point in the study of earthquakes, suggesting that earthquakes could be explained based on physical causes, and denied that they were an intervention of God in earthly affairs.
During the lecture, he described the shock not as chaotic motion but as a “kind of undulatory motion,” a kind of “wave of earth” like a wave of water—Winthrop being one of the first to provide such descriptions. As to a cause, he proposed that it was the result of a release of pressure created by a buildup of “fumes from fermenting minerals.” More specifically, it was an explosion of gases produced by the underground mixing of iron and sulfur with water, a combination that chemists had already shown could produce an excess of heat—and, hence, might power volcanoes—and, if the explosion was confined, could shake the Earth.
More than a century earlier, French chemist Nicolas Lémery had given a demonstration of how the process might work. He mixed equal parts of iron shavings and powdered sulfur into a large jar filled with water until he had a paste. He then secured a lid on the jar, had assistants bury it a few feet underground, covered the jar with dirt, and waited. After a few hours, cracks formed on the ground surface over the buried jar. Gases emitted from the cracks could be ignited with glowing embers. There were even individual underground bursts that shook the ground.
This idea—that earthquakes were underground explosions caused by the mixing of naturally occurring chemical compounds—was the prevailing one when Whitney attended Yale College in the 1840s. By the 1870s, the idea had been tempered and some authorities were now suggesting that the sudden strong quaking of the ground surface might be a product of the slow, constant cooling of an initially hot Earth, which caused the entire planet to contract, shortening the surface much like an apple eventually shrivels and forms wrinkles on its skin. In truth, in the 1870s, no one knew what caused an earthquake except in a very general sense, as Whitney and others wrote that it was an “impulse” occurring somewhere inside the Earth.***
Having surveyed the damage at Lone Pine, seen the scarp, cracks, and fractures, and having rummaged through hundreds of telegraph wires and newspaper reports, Whitney concluded that the “impulse” that had produced the Owens Valley earthquake had originated beneath the axis of the Sierra Nevada Mountains, not realizing that the evidence of what had actually triggered the shaking—and the physical cause of all earthquakes—was actually in plain view to him, Muir, and countless others. But it required someone else with a different perspective to see the obvious, to understand the significance of the 40-mile-long scarp that wound its way close to the cemetery where the earthquake victims were buried.
As was said during one of the many laudatory remarks made immediately after his death, geologist Grove Karl Gilbert from Rochester, New York, had merely looked out the window of a train on which he was a passenger and from that came up with a new theory of mountain building.
It was 1871, a year before the Owens Valley earthquake, and he was on his first trip to the American West, riding on the recently completed transcontinental railroad. The train was passing through northern Nevada—on the route followed by I-80 today—and through the window he watched as the train made its way over a series of mountain ranges separated by basins. Conventional wisdom held that such a sequence of ranges and basins was the result of compression, such as in the Appalachians, where the Earth’s crust had buckled and folded. But Gilbert saw no great folds in the mountains of Nevada. Furthermore, the mountain ranges gave the appearance of having been tilted, so that one side of a range was noticeably steeper than the other. To Gilbert, the explanation was obvious: A large area of the continent had been uplifted and then stretched.
The alternating pattern of mountain range and basin represented individual crustal blocks that, after being raised, had sunk to different levels as the crust was stretched, causing the blocks to tip slightly, like bergs of ice floundering in the sea. Gilbert gave a name to this topographically distinct area that covers most of Nevada and western Utah—the one that is used today by geologists and geographers and becomes evident to anyone who has spent seemingly endless hours driving the long, straight, almost always desolate but always majestic highways of this region of the continent: the Basin and Range Province.
Gilbert’s view was a totally new way of looking at the origin of some mountain ranges. And his creative mind did not stop there. Looking through a telescope at craters of the moon and wondering whether they were huge volcanoes or scars of meteor impacts—most scientists then favored a volcanic origin—Gilbert did his own experiments and threw balls of hard clay against slabs of wet clay, deciding, from a similarity in shape, that lunar craters had an impact origin. He also spent years studying the Great Salt Lake and concluded that what he was seeing was a small remnant of a previously vast body of water, which he named Lake Bonneville after an early explorer of the American West. From Gilbert’s work, we now know that this prehistoric lake once covered a third of the state of Utah, was more than 1,000 feet deep, and had emptied northward into the drainage of the Columbia River, leaving a very salty shadow of its former self behind thousands of years later. It was during one of his summertime trips to uncover more evidence for this ancient lake that he was on the western edge of the Basin and Range Province and decided to visit the site of the 1872 earthquake in Owens Valley After only a week of fieldwork, he was ready to propose a new theory of earthquakes.
Gilbert immediately realized that the key to understanding exactly what caused earthquakes was the long scarp that had formed during the earthquake. Unlike cracks and fissures that usually follow topographic contours, the scarp cut across streambeds and through hills, indicating that something deep in the Earth had controlled where it had formed. More important, as Gilbert studied the face of the scarp he noticed he could match features on one side of the scarp with features on the other side if the ground surface had slid as much as 15 feet horizontally!
Think of it this way: Take a newspaper column and rip it lengthwise along a straight line. Now shift the two parts and place them against each other. You can tell the amount of the shift by matching original lines of type. In the same way, by matching arrangements of rocks and other subtle features—known today in geology as finding the “piercing points”—Gilbert could tell that the ground surface had shifted horizontally along the scarp. And that was the great realization: Ground shaking and the pull of gravity would have caused a downward settling, like shaking a bag of rocks, and so motion along the scarp, if it was a secondary feature, should have been vertical. But the markings on the scarp ran horizontal—and by as much as 15 feet. From that, Gilbert concluded that the formation of the scarp was not an effect of the 1872 earthquake, but the cause. The Earth’s surface wasn’t moving up and down but side to side. But why?
Gilbert hypothesized the following: Imagine, he said, that you are in a railway car and the brake is set. Then if the car is being pushed or pulled, at first the car remains stationary, held in place by friction of the iron wheels against the rails. But eventually the pushing or the pulling becomes too great and the wheels slide a short distance along the rails, causing the entire railway car to shake momentarily.
According to Gilbert, a similar thing happens inside the Earth. In that case, some force, some impulse—which would not be known for another 80 years—causes strain to build up within the Earth’s crust. That strain is released—like between the wheels and the rails—when crustal blocks slide a
gainst each other. And because there is friction between the blocks, seismic waves are produced.
Today this all seems so obvious, but in 1883, when Gilbert did his work in Owens Valley, it was revolutionary. And, as often happens with a new idea, it was ignored—in this case for more than 20 years.
Not until 1906, when an earthquake devastated San Francisco and the surrounding area, did geologists readily accept Gilbert’s idea that earthquakes were caused by the sliding of crustal blocks. That earthquake, as will be shown, gave undeniable proof that the sliding of crustal blocks had caused the shaking. Barely a decade before then, someone had discovered the San Andreas Fault.
*Intriguingly, the white granite can be seen exposed at several famous golf courses in Carmel, including Pebble Beach and Cypress Point, the layouts of the fairways controlled by the contour of the granite.
**In a similar vein, if Muir and others had known more about glaciers and their ability to scour and erode, he probably would not have proposed a glacial origin for Yosemite Valley. It would not be until 1913, when Francois Matthes, a geologist working in national parks, disposed of the earthquake theory and downplayed a glacial origin. Today, the general opinion is that Yosemite Valley is an erosional feature formed by river erosion and exfoliation of granite. The flat valley floor owes its existence to sediment trapped in shallow lakes that formed during a retreat of the glaciers.
***Here there is a coincidence that spurred on the idea—at least to Whitney—that earthquakes were underground explosions. In July 1872, while Whitney was writing his report about the Owens Valley earthquake, a nitroglycerin factory exploded in San Francisco. Windows rattled and walls shook for miles around, prompting Whitney, who was in the city at the time, to write “… we have only to imagine an impulse given, like that produced by the nitro-glycerin explosion—only on a vastly greater scale—to produce all the effects of the most disastrous shock.”