Posted by Tom_in_CA on 3/21/2008, 6:05 pm, in reply to "PI - iron mask and "orphan" silver"
207.200.116.134
Thanx for the topic. I've been beating this dead horse for quite awhile on this forum 
Yes, it's no secret that if you went out to inner-city urban old parks, and dug every signal with a PI or a VLF set to all-metal, that you'd get down a a layer of deeper coins in some of those parks, that could be reached in NO other way. But the problem is, this "strip-mining" is not always an option. At some, you'd get downright embarassed to be digging all those deep paper clips, BBs, etc... Any one of those paper clips or deep nails *might* be a cool tinsel thin gold chain, or an earing stud, or the next 12" deep seated dime. Sure. But to dig 100 holes for each keeper, will usually drive a person back to "at least" knocking out iron, and giving up the extra few inches of depth, (& possibility of masked targets.)
I know of some ruins sites where I am absolutely convinced that some portions are so iron-riddled, that ..... based on the # of seateds and reales found around the peripheries of those zones, that there must, by common-sense-logic, be coins that are being masked, too deep, etc... in that iron zone. But to think that I could strip-mine all them out, or switch to all metal to reach some 12" deep coins on the peripheries, would drive me mad. I would probably actually be better off just to take a shovel, and slowly and methodically shovel off the top 6" of soil in an area the size of my living room. Then just conventionally detect in the scraped area. That's how much dirt I'd end up moving in the end, to think I could strip-mine every signal out anyhow.
Sure, parks are not this junk/iron riddled as my ruins-spot, but the same concept applies d/t too many deep holes raises the ire of gardners and such. I wouldn't mind digging a lot of deep holes if had a relatively good idea of iron vs non-iron, and better yet, highs vs lows. But for a lot, to "dig all" is not an option.
I hunted a park in an 1860s side of SF, that got scraped to make way for astro-turf. When they got down to 12" deep in the scrape, every single coin was old (all seateds, barbers, etc..). It became clear to us that were hunting this, that there was simply no way a person could've reached these, at current machine's depth ranges, unless this scrape had occured, or unless a person had elected to "dig all". Even at the 12" scrape level, we were passing all sorts of iron (shallow now of course, so easy to see through and around), but I would pity the poor fellow who'd have tried to reach these before a scrape.
If a machine is made that can see conductors, and pass iron, at depths beyond what's currently available (9" or 10" max), you'd have the next great silver rush. Remember when the 6000d was introduced in 1978? The first guys to take those to parks/schools had an easy time getting 5, 10 and 15 silvers at a pop, simply becuase it went 2" deeper than the current TR disc, and did it FAST!
Sure, some places depth is not the issue, or they are types of spots (CW hunting mindset, beach, etc...) where persons didn't mind digging out every speck of iron. But there is still a market for spots where persons, by the very nature of the spot, have had to be a little more discreet in the targets they chose to dig. That simply leaves a zone waiting to be opened up, at the first sign of increased depth with retained iron ID.
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