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Updated: May 14, 2025
Lindgren, the geologist, affirms that after the Sierra Nevada range was thrust up, high into the heavens, vast and long continued erosion "planed down this range to a surface of comparatively gentle topography." He claims that it must originally have been of great height.
He went up into the mining region near Grass Valley in the Sierras where he had already studied with Waldemar Lindgren, and became a regular miner, a boy-man with pick and shovel working long hours underground or sometimes on the surface about the plant. But always he had his eyes wide open and always he was learning.
The young geologist's association with Lindgren, whose standards of personal character and regard for the dignity and ethics of his profession were of the highest, was a source of much valuable education.
Two summers were spent in work with the U. S. Geological Survey in the California Sierras around Lake Tahoe and the American River under Waldemar Lindgren, one of the greatest of American scientific mining engineers.
"None of the craters," says Lindgren, "of these volcanoes are preserved, and at the time of their greatest activity they may have reached a height of several thousand feet above the present summits." We have already seen in the preceding chapter how the great basin, in which Lake Tahoe rests, was turned out in the rough from Nature's workshop.
On the summits nearer to Tahoe the volcanic outflows were of andesite, a rough and porous rock of dark gray to dark brown color. Lindgren says: "By far the greater part of the andesite occurs in the form of a tuffaceous breccia in numerous superimposed flows.
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