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The scientist and the shepherd
Josiah Whitney, John Muir and the origins of Yosemite
Josiah Whitney in the 1860s was a distinguished scientist—professor of geology at Harvard, head of the California Geological Survey, consultant to government and corporations, and mentor to the junior scientists he gathered around him. The highest peak in California and in the United States at the time was named for him; likewise the largest American glacier discovered till then.
John Muir was a generation younger than Whitney and unknown in the world of science. Born in Scotland, Muir emigrated to America with his family at the age of eleven. His father had fallen out with the Church of Scotland for being too lax; Muir pere found comforting rigor with the Disciples of Christ in Wisconsin, where John found forests to roam. The young man started college at the University of Wisconsin but fled to Canada during the Civil War to avoid the draft. An industrial accident after the war nearly blinded him, and he swore off civilization in favor of the wilderness. He walked a thousand miles to Florida, where he commenced a ship-hopping journey that finally landed him in California.
He headed at once for Yosemite, the Sierra valley revealed to white adventurers only the decade before but already spoken of with awe. He fell in love with its grandeur and beauty; for the rest of his life it was the mother church to his religion of nature. He took a job as a shepherd so he could stay in the area; he built a cabin on the banks of Yosemite Creek lest he miss a moment in the valley.
Josiah Whitney and John Muir both wondered what forces had raised the mountains that ringed the valley and carved the cliffs over which waterfalls leaped thousands of feet to the valley floor. Whitney’s explanation had the authority of science and of the institutions that backed the great man. It also accorded with what was known of mountain-building and valley-carving at the time. Whitney recognized the role of water and erosion in shaping the numberless canyons that cut v-shaped profiles in the flanks of the Sierra Nevada. But Yosemite was different, he said. Its walls weren’t slanted like those of most canyons; rather they were vertical. Nor was the detritus of erosion found on the floor of Yosemite Valley, as it was found on the floor of the typical canyon.
The distinctive profile of Yosemite Valley, said Whitney, was caused by the collapse of the valley floor consequent to the removal of mass beneath it. Whitney didn’t know the mechanism for the removal, but he assumed it was related to the larger forces that had thrust the entire Sierra Nevada range skyward. “The bottom of the valley sank down to an unknown depth, owing to its support being withdrawn from underneath, during some of those convulsive movements which must have attended the upheaval of so extensive and elevated a chain, no matter how slow we imagine the process to have been,” he wrote in The Yosemite Guide-book. After the initial subsidence, ordinary erosion had produced the talus slopes at the base of El Capitan and other cliff faces and produced the soil that anchored the trees and bushes along the Merced River in the valley bottom. But erosion could never have produced the sheer walls that made Yosemite so different from other canyons of the Sierra.
John Muir heard Whitney’s explanation and didn’t buy it. Muir spent more time climbing up, around and over the cliffs and domes of Yosemite than Whitney or anyone else, until he knew their granite like his own skin. And like his skin after a scramble through the underbrush of the Sierra, the granite bore scratches. Muir concluded that such scratches could have been caused only by glaciers that must at one time have filled Yosemite Valley nearly to the brim.
When Muir proposed glaciers as the sculpting agents of Yosemite rockforms, Whitney sneered. “A more absurd theory was never advanced,” he said of Muir’s conjecture. Whitney knew, as Muir did not, what glacial carving looked like in the Alps of Switzerland. Where were the glacial moraines—the ridges of pulverized rock left by the glaciers? Where were the glaciers themselves? “There is no reason to suppose, or at least no proof, that glaciers have ever occupied the Valley or any portion of it,” Whitney said. “This theory, based on entire ignorance of the whole subject, may be dropped without wasting any more time on it.”
Muir didn’t drop the theory. Instead he searched for the missing evidence. And he found enough to confirm his beliefs. “Though the gigantic glaciers of the Sierra are dead, their history is indelibly recorded in characters of rock, mountain, canyon and forest,” he wrote in Studies in the Sierra. The missing moraines no longer existed as distinct ridges the way moraines did in some other parts of the country; post-glacial water erosion had carried most of their materials down to the Central Valley of California. He found remnants beneath the vegetation in various parts of Yosemite. As for the missing Yosemite glaciers, they had melted along with the ice sheets that had covered much of North America during the last Ice Age.
Muir mentally reconstructed five glaciers that had covered much of the Yosemite region. He wrote picturesquely of one, the Illiloutte glacier. “The ice-plows of Illilouette, ranged side by side in orderly gangs, have furrowed its rocks with admirable uniformity, producing irrigating channels for a brood of wild streams, and abundance of deep, rich soils, adapted to every requirement of garden and grove,” he said. “The Illilouette basin is one grand garden embellished with rocks.”
Muir threw the charge of lack of proof back at Whitney. Where was his evidence of the subsidence he posited? What mechanism drove the collapse of the valley floor? Whitney had none, Muir said.
By contrast, Muir’s glacial theory fit the evidence, and its mechanism—the force of gravity acting on the millions of tons of glacial ice—was commensurate with the result. “With glaciers as a key, the secrets of every valley are unlocked,” Muir wrote. “Streams of ice explain all the phenomena; streams of water do not explain any; neither do subsidences, fissures, or pressure plications”—the folding of rocks.
Muir won the argument. In time geologists became convinced that glaciers indeed were the sculpting agents of Yosemite. Whitney was wrong.
But he was wrong only about Yosemite. He was right about the series of valleys east of the Sierra Nevada and extending across what became known as the Basin and Range Province. Of these valleys the most spectacular is Death Valley, and it formed much as Whitney conjectured Yosemite had formed: by the collapse of the valley floor. In Whitney’s day, no one knew of plate tectonics and how the slow movement of continental plates causes buckling that raises mountain ranges and makes the land between the ranges subside. Whitney and other geologists observed the buckling but thought mistakenly that it was the result of shrinkage of the earth’s interior.
Muir and Whitney did agree on one thing: the necessity of preserving Yosemite for future generations. Whitney was the first to promote national parks and became a powerful voice for Yosemite’s inclusion on the list; Muir propagated the gospel of Yosemite and wilderness through the Sierra Club, which he headed for twenty-two years. Today’s visitors to Yosemite National Park owe a debt to both men.