...near where it crosses the L.A. Bay highway.
I pulled off between Km. posts 30 & 29, to the north,
on a dirt road. Just beyond where I parked, I found it.
Above photo looking southeast. 29°02.00'/ 113°52.82' (NAD27).
On to El Volcan...
Four miles northeast of the El Marmol onyx schoolhouse,
the process by which onyx is made can be seen, at El Volcan. Several
mineral springs where onyx is created (about an inch every thousand years)
are in the arroyo and a quarter mile beyond. The biggest spring is on top
of a thirty foot dome, which erupts once a month. This cold water geyser
is how El Volcan (The Volcano) got its name. For several minutes water and
gas is sprayed 60 feet into the sky!
If you cross Arroyo El Volcan and continue 0.3 mile on the La Olividada road,
this white slope of tiny onyx springs is passed.
At the bottom of the long grade is Arroyo El Volcan (misnamed 'Zamora' in Almanac).
We drove south (in the wash) 0.2 mi., then hiked. Beautiful pools here!
This pool seemed bottomless!