Much
of the Yuba Goldfields are private property, but there is a small
portion managed by the BLM that is publicly available. The only
access is on Hammonton Road (N39 09.937 W121 27.089). This road
quickly turns into an unmaintained dirt road that is easily
passable with a passenger car. Just watch out for the potholes. The
no trespassing signs along the side of the road are to keep you on
the road.
The Yuba Goldfields have been dredged for gold
since 1904. Dredging uses massive buckets on a conveyor belt style
system to dig up ancient river sediments. The machinery is located
on a floating barge since the digging creates a pond. As the barge
digs it way forward it constantly sits in its own pond. The gold is
separated from the tailings (all the other rock) on the barge and
the tailings are piled up beside the barge in tall linear piles as
it moves along. The coordinates are on one of these piles of
tailings.
In a single year, each dredge could excavate 26 million cubic
yards of material. That is equivalent to a 100 football fields
filled two stories high.
In the 1930s 12 dredges were operating and expanded to 21 in
1968. 1 billion cubic yards of material had been dredged for gold.
The number of dredges decreased after 1968 and temporarily stopped
in late 1976. Dredging resumed with one dredge at a deep reserve
(140 feet below the water) from 1981 to 2003. Currently dredging
has been suspended until a barge can be restored to resume
operations.
The source of the gold in the Yuba Goldfields is a placer
deposit. A placer deposit is a natural concentration of a mineral
by surface, typically river, erosional forces. In this case, gold
was eroded out of the Mother Load gold deposits in the Sierra
Nevada to the east. The ancient Yuba River transported the gold
downstream where it was deposited on the inside of meaner loops, in
covered rock holes, and other typical gold traps.
The density and chemical inertness of gold are the primary
characteristics that create gold placer deposits. Gold is a very
dense metal. For that reason, gold will get lodged in the river
bottom wherever the current slows down even slightly and will work
its way down below other rocks. Gold is also inert which means it
does not react with other compounds. Thus gold will remain gold
pretty much no matter what else comes in contact with it.
Two buckets from the dredging system are located
at the secondary coordinates (N39 12.234 W121 24.778). On average,
each bucket contained about 3 nuggets the size of a pinhead. (see
the image to the left)
Currently the dredge tailings are being mined for aggragate.
Once Cal Sierra Development refurbishes the dredger they plan to
resume dredging for gold in deep placer deposits.
Logging requirements:
Send me a note with :
- The text "GC1CXZ9 Yuba Goldfields" on the first line
- The number of people in your group.
- At the primary coordinates,
- Describe the size of the rocks in the tailings pile.
- What is the height of the pile from the water level to the top.
(the water is to the west)
- At the secondary coordinates
- Compare the average amount of gold found in each bucket to the
size of the bucket.
The following sources were used to generate this
cache:
- Cal Sierra Development Inc., History,
http://calsierradevelopment.com/
- Step by step River Gold Formation,
http://www.e-goldprospecting.com/html/gold_step-by-step.html DEREK
WILTON, Placer gold deposits, Pt. 1, October 6, 1997, The Northern
Miner,
http://www.northernminer.com/Tools/Geology101/geo101pg2.asp
