Other References:
 Geology and Natural History of Lake Tahoe at ceres.ca.gov

 Geological History at LakeTahoeCam.com
 Geology at TahoeThisWeeek
 Timeline
 Geologic Information about California at the USGS
 The Lake Tahoe clearinghouse for geographic (GIS) data

155-300 million yrs. ago the North American continental plate drifted away from the super-continent of Pangea and moved westward. It collided with a Pacific Island chain in an area which is now the Sierra Nevada.

163-143 MYA compression caused uplifting of the Sierra Nevada to about 3/4 of present height.

The primary force creating the lake was uplifting along fault lines which created the Sierra Nevada and Carson ranges with Lake Tahoe in between from 4-25 million years ago.
A series of volcanic eruptions added to the landscape 5-25 million years ago.

The outlet and level of the lake has changed many times. 1-2 million years ago Mt. Pluto and other volcanos to the north blocked the outlet near Truckee. A new outlet was cut just east of Mt. Pluto.

More recently (2 million to 20,000 yrs. ago) glaciers blocked the outlet. The lake has been up to 800 ft. above its present level in the past. The current outlet at Tahoe City goes into the Truckee River which flows through Reno to Pyramid Lake where it evaporates.

Throats of ancient volcanos remaining after the outer layers were eroded: Cave Rock, Eagle Rock, Castle Peak, Mt. Lincoln.

Up-thrown peaks: Freel Pk. (10,881'), Monument Pk. (10,067'), Mt. Tallac (9,735') * Pyramid Pk. (9,983')

* Mt. Tallac is listed as a volcano in one source and an uplifted peak in another.

Sierra Peaks Regional Data

Links:
Earthquakes
Geography & History Overview and Facts about Lake Tahoe at the U.S. Geological Survey