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The Kennedy Mine was one of the large-scale gold mines that worked the
“mother lode” in the Sierra foothills of Northern California. It’s a
kilometer and a half north of Jackson, off of Highway 49 that links many
of the historic towns and ruins from the 19th century gold rush era.
First developed in 1860, the mine’s successful commercial operation ran
from 1886 through 1942. In its heyday it was the deepest mine in the
United States, with a main shaft that descended over 1,800 meters. Today
it’s a historical site featuring the distinctive wooden tailing wheels
that have become local landmarks.
Gold mining in California was an environmental disaster. It involved
crushing large quantities of ore dug from underground or stripped from
the surface, and then washing it with lots of water (or sometimes toxic
mercury) to separate the heavy gold from the lighter rock. Most of the
“mother lode” isn’t exactly loaded with gold. The Kennedy Mine is
estimated to have extracted slightly less than 16 grams of gold per
tonne of ore, a typical ratio for California mines. That one operation
generated some 342,000 tonnes annually of tailings, the crushed
rock residue. Mines originally dumped their tailings into the nearest
river or creek, polluting farms and endangering navigation.
By the beginning of the 20th century, extensive litigation and an early
federal environmental law forced mining companies to stop their dumping.
Tailings now had to be “impounded” in a landfill. That created a problem
for the Kennedy Mine, since the nearest practical place to impound the
tailings was nearly a kilometer away and behind two hills.
Engineers devised a unique solution to the problem in 1912. They built
four elevator wheels, each 18 meters across and made of redwood. The
wheels each held 208 buckets that filled with a sludgy mixture of
crushed rock and water. A wheel lifted the tailings about 12 meters, and
emptied the buckets into flumes that led to the next wheel. This
mechanical bucket brigade carried the tailings over the hills to the
impound pit. Operating around the clock, the wheels could move 937
tonnes of waste daily.
The wheels were originally enclosed in corrugated iron sheds. When war
regulations effectively shut down all gold mining in 1942,
the mine’s owners dismantled the sheds for scrap but left the wheels.
Without their protective sheds, two of the wheels have rotted and
collapsed into “artistic” piles of wood and metal hardware. The other
two are preserved in a state of “arrested decay.”
The owners decided not to reopen the mine after the war, as the main
shaft and the other 80 kilometers of underground tunnels had become
flooded with water. A San Francisco teacher bought the former mine’s
62-hectare site at a liquidation sale in 1961. She lived in a house on
the mine grounds until she died in 1994. Her will specified that the
mine’s remains be preserved as a historical site.
Indian Grinding Rock State Historic Park is another nearby attraction,
13 kilometers east of Jackson. The park gets its name from a large
limestone outcropping into which Miwok Indians dug 1,185 mortar holes
(yes, someone actually counted them). They used the holes and stone
pestles to grind their staple food, acorns from the abundant valley oak
trees. The Miwok called the rock Chaw’se, which means
grinding rock.
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