Remnants of the jackline plant on PCO Hill at the back of Pico Canyon; no later than January 1962.
According to 1960-66 Mentryville resident Darryl Manzer, "I watched it get buried when Standard Oil was making a place to re-drill an old well.
... It went under that dirt about 1965 (along with its) big eccentric wheels and the gearing."
Further reading:
Pico Canyon / Mentryville Index
The Pico Ghost Camp by Arthur B. Perkins, 1962.
The Only Kid in Mentryville by Darryl Manzer, 1997.