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Climatic data for the Sierra Nevada are compared with the range of climatic conditions that are inferred to have occurred during the last 10,000 years. A model of paleoclimatic fluctuation based chiefly upon variation in mean seasonal snowfall is derived. Using a model based upon fluctuations in mean snowfall of less than 50 percent of the mean snowfall during the standard climatic normal period (1931–1960), I propose a chronology of climatic fluctuations for the Sierra Nevada for the last 10,000 years. This chronology is based upon paleoclimatic data derived from study of geologic deposits dated by radiocarbon and lichenometry, variation in tree rings, changes in timberline position, vegetational age classes, and direct and indirect historical records.

At least four major periods of increased mean snowfall and cooler, cloudier summers during the last 10,000 years resulted in four periods of multiple glacial advance in the Sierra Nevada. These occurred between 6000 and 7000 years ago, between 2000 and 2600 years ago, around 1000 years ago, and between 650 years ago and the present. The latest major period of net accumulation and advance in all cirques that are presently occupied by residual glaciers occurred between 1880 and 1908 with a peak from 1895 to 1897.

The fluctuations from glacial to interglacial climate that are presently known to have occurred during the last 8000 years can be fully explained by a climatic model in which the extremes of mean precipitation for the 96 years of historical record are greater than the range of long-term means for that climatic parameter.

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