This is the same sort of chert that we saw at stop 1, but from an earlier episode of subduction in the Triassic Period (250–200 Ma). Even after all the squeezing and pushing of later events, this is still a recognizable radiolarian chert, almost entirely silica. Had there been any clay content, this rock would probably be a nice clean-splitting slate by now.
The field-trip guide appears to have the wrong GPS position for this stop. By my reckoning it is 40°0.97´N, 121°12.79´W, about 0.5 mile past the Caribou Road turnoff.
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