What You Really Need to Know About Tertiary Channels (5)
(Miners hydraulicking Tertiary gravels at the Malakoff Diggings outside Nevada City, California back in the day.)
At face value, the placer gold potential of Tertiary Channels seems pretty attractive to small-scale miners. However, all is not as it seems when it comes to accessing and, more importantly, working gold-bearing Tertiaries.
3) Working Tertiary Channels
OK, here we go with a knock-out punch right between the eyes. Most, if not all, small-scale placer mining equipment, techniques, and methods ARE NOT suitable for mining Tertiary Channel gravels. The truth hurts sometimes and what I'm passing along to you is the truth, like it or not.
Gold Prospecting Books
Location is one thing when it comes to Tertiaries and working them is a different beast altogether. Your little suction dredge, your highbanker, your sluice box, or your dry washer aren't going to prove very useful in working most Tertiaries efficiently or effectively (if you can work them at all with this sort of approach).
Dig Down a Bit
One reason is that Tertiary paystreaks are often located high above existing stream courses and dry as a bone in terms of accessible water for processing them. Oh sure, you can pump water up to them but try doing that with a highbanker and 800-1,000 feet of hose trailing down the hillside. How much water pressure do you think you'll have to process material?
(Hit a "virgin" Tertiary Channel and work it the right way, and this sort of placer gold could be the pay off. Collection of nuggets from California's Ruby "drift" mine.)
Sure, this is a somewhat facetious and extreme example but it holds truth just the same. Use a dry washer then? That may work in some instances but most Tertiary gravels I've come across in N. California's Motherlode were only dry close to the surface. Dig down a bit and they become damp or even wet...you can't run that sort of material through a dry washer and have great expectations for good gold recovery.
Just About Useless
There are some Tertiary gravels adjacent to or underneath existing stream courses that you'll probably be able to work but chances are they've been worked before by someone, sometime, somewhere else along the line. There'll still be some gold left for you in these sorts of contexts, but nothing like the potential of digging into and processing material from a Tertiary Channel that hasn't been properly mined.
Another thing to consider here is that most Tertiary paystreaks are very deeply buried under layer upon layer of overburden. If you don't have a hillside cut exposing them, then brothers and sisters your puny little pick and shovel are just about useless...what you need in these instances is BIG equipment or the patience and fortitude to "drift" mine (something I'll talk about later).
Until next time...
If you liked this post, you may want to read: "Gold in the West: Idaho (Part 5)"
(c) Jim Rocha (J.R.) 2012
Questions? E-mail me at firstname.lastname@example.org