"The Heavies Drop Out First" (Part 6)
Well it's time to throw a bit of a monkey wrench into this heavies thing. Ready? Because we're gonna talk about heavies and how they behave in dry placer areas, since the focus thus far has been primarily on wet placer heavies deposition.
"Blah, Blah, Blah"
You old timers, mining veterans, and astute newbies already have a pretty good idea of what's at stake in heavies deposition in dry placers...that is, if you've worked dry placers at some point or another. I know that I've crowed and crowed about my dry placer experience a hundred times, so bear with me yet again. I really did cut my small-scale gold mining teeth in the desert placers of southeastern California and southwestern Arizona, so I really DO know of which I speak. I've also done a fairly good amount of dry placer digging here in New Mexico as well as Old Mexico itself (including Baja). In other words, I have a lot of dry placer mining experience under my belt.
(Dry washing for gold in the desert is for the hardy...and slightly crazy!)
Quite a Damper
Dry placers present some of the most contrary and ornery gold digging you will ever experience. That's not to say dry or desert gold is hard to get...it really isn't once you get a line on things. But getting there will drive you absolutely crazy at times. Why is that? Well, simply because dry or desert placers don't get much rain or water movement of any sort. That puts quite a damper on the consistency of gold and other heavies deposition. However, when the rains do come those gold-bearing washes and arroyos get hit by flash flooding, some of the most powerful and scary stream hydrology you will ever experience. I've seen huge boulders weighing 500-1,000 pounds or more lifted out of position and tumbled downstream by heavy flash flooding in the desert, so you can imagine the effect that sort of hydraulic power has on gold and heavies. Everything (and I mean everything) is likely to get uprooted and hauled downstream. That's in the heaviest flash flooding. In more mild flooding situations (if mild is the right term to use here) some of the largest wash or arroyo obstructions may remain in place but the heavies will be on the move just the same.
(I wasn't joking about those huge boulders getting moved in flash floods.)
Now here's a tip for you. Those desert flash floods invariably take place in the late spring or summer months in California, Arizona, and New Mexico which means the likelihood of you or I hitting those affected gold-bearing spots immediately after that flooding is slim at best. Only mad dogs and Englishmen would venture into triple digit temperatures at such times. Then how could I have seen such flooding? Because I'm a lunatic at times. Especially when I was new to this mining gig and couldn't control my gold fever. Anyway, I don't make that sort of thing a habit any longer, nor should you. But, if for some untold reason you do venture into desert placers in the summer months, stay the hell away from those arroyos and dry washes if thunder heads are rumbling off in the distance. My readers are smart people, so don't prove me wrong on that point, OK?
Just About Anywhere
OK, so the heavies get moved like SOBs in desert flash flooding but where do they end up? Here's where you gotta think outside the box. The answer? Anywhere and everywhere. The reason for this is that desert flash flooding ends as quickly as it begins. When that hydraulic force stops, it stops abruptly for the most part and so do the gold and other heavies. The yellow stuff will tend to form in small pockets and paystreaks where it dropped as soon as the flood waters quit racing downstream. These pockets and paystreaks may be on bedrock, just above bedrock, behind any sizeable obstruction, near the surface or lining the inside bends of arroyo walls (i.e., benches). In this latter case I've found fairly extensive pay in benches at times, so don't neglect those in your search for desert gold. Hell, to be truthful, those heavies can be just about anywhere after flash flooding in the desert. I've dug down to shallow bedrock after these sorts of events (often months later) and found nada, zip, zero. Then I've come across very nice pockets resting behind obstructions within five or six inches of the surface. Ma Nature's deposition mode in the desert is erratic at best, so remember that point. Be open to the possibilities and try to visualize that wash or arroyo in full raging flood, rocks, gravel, sand, and old junked cars tumbling downstream. Then imagine that same arroyo or wash when the water abruptly stops. What you see in your mind's eye is where you want to start digging and sampling.
(One day's take of desert gold I got in a New Mexico dry placer behind a large boulder. All of it was in the top six inches of gravel.)
Here's another tip. There is a distinct similarity between dry and wet placers in the sense that when those heavies start showing up in your dry washer or test pans so should the gold. So if old bits of rusty metal, lead shot, nails, etc., start appearing, you're probably onto something. That said, dry placers are mucho loco. Gold will show up without accompanying heavies and vice versa. Makes you want to pull your hair out doesn't it? Well my friends, that's the nature of desert gold.
As always, there's more to come. Be safe out there.
(c) Jim Rocha (J.R.) 2016
Questions? E-mail me at firstname.lastname@example.org