Stop 19 is at 39°54.978´N, 120°49.542´W east of Quincy, exposing the Sierra's oldest ophiolite. (more below)
Geology Guide photo
This is the oldest body of ophiolitic rocks in the Sierra Nevada; a related granite is dated at 500 Ma, during the Cambrian Period. It also happens to be the darkest serpentinite I came across in the field trip. It is thrusted over rocks belonging to the Shoo Fly Complex (stop 17), or rather they are thrusted beneath it. This is a typical subduction-related pattern that should be familiar by this time.
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