David P. Adam
1973
<p>Fossil pollen was recovered at Tahoe City, Calif., from beneath a 1.9-m.y.-old volcanic flow. Pollen counts of four fossil samples are compared with soil-surface pollen samples from the Sierra Nevada. The presence of <i>Picea</i> (spruce) pollen in the fossil samples suggests that summer drought conditions in the central Sierra Nevada were less severe prior to 1.9 m.y. ago than they are now.</p>
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U.S. Geological Survey
Early Pleistocene(?) pollen spectra from near Lake Tahoe, California
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