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Stop 27, Auriferous Gravels: The Setting

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Stop 27 is at a rest stop at 39°10.772´N, 120°51.334´W, exposing the Eocene pay dirt. (more below)
A little piece of the gold beds
Photo (c) 2006 Andrew Alden, licensed to About.com (fair use policy)
These gravels originated during the Eocene in rocks somewhere deep in Nevada beyond today's Mother Lode country, from highlands that are long gone. Most of the gravel was overburden, the gold-bearing zone being at the bottom. Remnants of the auriferous gravel have been well mapped, starting with Waldemar Lindgren's 1911 publication "Tertiary Gravels of the Sierra Nevada of California." This exposure is also part of the railroad's ribbon of land that escaped the hydraulickers. At this spot the Eocene gravels are topped by igneous deposits of the much younger Mehrten Formation, showing that little tectonic activity had occurred in some 45 million years.

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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