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Stop 23, Sierra Nevada Batholith: The Setting

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Stop 23 is at 39°18.999´N, 120°19.548´W, at old Donner Summit overlooking the east edge of the Sierra Nevada. (more below)
The Sierra's heart
Photo (c) 2006 Andrew Alden, licensed to About.com (fair use policy)
This is a compelling site for human as well as geological reasons. Donner Pass was a very difficult overland crossing, first traversed in 1844 and made notorious two years later by the ill-fated Donner party. It is worth standing here and contemplating the stern stuff of which the pioneers were made. The completion of the transcontinental railroad in 1869 turned this passage into a much less deadly challenge and eventually into a tourist attraction—in good weather.

The rocks here are classic granites of the Sierra Nevada Batholith. A batholith is a very large bottomless pluton of greater than 100 square kilometers extent. The view east from here covers the edge of the Sierra microplate and the Basin and Range province beyond.

Day 1, Coast Range: 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9

Day 2, Sierra Nevada: 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18

Day 3, Sierra Nevada: 19 | 20 | 21 | 22 | 23 | 24 | 25 | 26 | 27 | 28

Day 4, Coast Range: 29 | 30 | 31 | 32 | 33

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