Geologic Trip, Northern Sierra
This photograph, taken from McGlashan Point on old Donner Pass Road, looks eastward toward Donner Lake. McGlashan Point is near the top of the steep eastern escarpment of the Sierra Nevada, about 1,000 feet above Donner Lake. This escarpment was formed by faulting along the Sierra Nevada fault zone. The Sierra Nevada was uplifted an estimated 1,800 feet along the fault zone, which lies between McGlashan Point and Donner Lake. Looking east from McGlashan Point you can see down the U-shaped glacial valley of the Truckee River. During Pleistocene time, glaciers from Donner Pass eastward down this river valley. From here, you can see the lateral moraines that were formed by the glaciers on both sides of the valley, and the recessional moraine that forms the dam at the far end of Donner Lake.