Page:Popular Science Monthly Volume 85.djvu/77

Rh out." The commonplace processes of work-a-day life psychologically bore their imprint in their deductions. Miners could only see gigantic excavations. The metallurgist would detect an apparent analogy in the swelling of these domes to the bubbling and solidification of molten metal. Engineers were most impressed by the evidences of stresses, strains and the rupture of weaker materials.

One of the most ingenious interpretations of the subsidence theory was advanced most ingenuously by one of the gentler sex. To newcomers in the Yosemite I was explaining the "cataclysmic hypothesis," still popular with those who prefer the more spectacular speculations. Suddenly, she exclaimed: "Did you ever bake a cake?" I answered proudly in the affirmative. "Well, did you ever spoil a cake?" Again, but with less pride, I admitted that such had been my experience. "Then you will know," she continued, "how it is that heat and the gas formed by baking-powder make the batter rise. Up it swells. Then a crust forms. If all goes well, the cake becomes crisp and compact. But, if some one jars it, while it is rising, down it drops in the middle. And so I guess the Yosemite Valley must have dropped in just such a way." This homely homology from an expert in culinary science was unanswerable. Her mind was made up. Even the most uncompromising glacialist could only have caused her to concede that the ice sheet was but a frosting spread over the surface of her hypothetical cake.

During the summers of 1863-4, Professor Josiah Dwight Whitney, chief of the California Geological Survey, conducted a most thorough reconnoissancereconnaissance [sic] of the Yosemite and High Sierra region. In his first report, published in 1865, he advanced his theory that the Yosemite Valley had been formed by the subsidence of a limited area during the processes of upheaval of the Sierra. This supposed sinking of its floor he attributed to the fracturing of its strata in a series of cross fractures and faults traversing each other, generally at right angles. The pioneer geologist declared that "this great cataclysm may have taken place at a time when the granitic mass was in a semiplastic condition below, although, quite consolidated at the surface and for some distance down." But Professor Whitney must not be misunderstood as maintaining that the gorge of the Yosemite is one gigantic fissure. Later, in 1870, in his celebrated "Yosemite Guide-book," he demonstrates that "the valley is too wide to have been formed by a fissure." Had such been the case its opposite walls would have corresponded in most details, instead of differing as notably as they do. Rather did he regard its fracturing as having been the resultant of a chaotic complication of dislocations. Believing that its supports had been withdrawn during the convulsive movements of the plastic strata, he assumed in his homely phrase that "the bottom of the Yosemite dropped out." When pressed for further evidence to support his theory, he could show no conclusive, concrete