It sounds like a practical application of the drunkard's search (streetlight effect), to me:Soil sampling itself has always been a major exploration method. There are geological reasons why this seems a bit unusual (roads are not the best places to sample as a rule).
Yep, one of the local quarries in my area that frequently gets used for road metal is known to have structures that carry a bit of subeconomic grade. Only half-gram kind of numbers but at geochemical detection levels that's going to ruin your program if some of that got into a sample.Soil sampling itself has always been a major exploration method. There are geological reasons why this seems a bit unusual (roads are not the best places to sample as a rule).
Also the roads where the material was spread - keen eyes were watching during the day (not mine, unfortunately), and came out after dark with torches, to grid the day's fresh roadworks. Back in 1984 I saw and held a 17 ouncer (with fresh grader marks!), found the night before on a gravel road in the Golden Triangle.A lot of local quarries provided base and topping for heaps of tracks/ roads in the gt. Most of the quarries got a good going over with reasonable results on a regular basis. (VLFdays).
No, roads are good to drill along (e.g. to get a complete linear cross-section of what is beneath). Local council gives permission (one letter) and no private agreements have to be reached with landowners for every property entered - can save $100,000 and up to 2 years of time. Not so good for most soil methods, as they depend on sampling the correct soil horizon, and areas along roads have usually been turned over. Worse, as Redfin notes, topping from elsewhere can be added, There is another reason why I am surprised for that particular geographic area, but a bit complex. HOWEVER road reserves that have never seen a graded or sealed road can be fantastic because the soil can be pristine....It sounds like a practical application of the drunkard's search (streetlight effect), to me:
https://en.wikipedia.org/wiki/Streetlight_effect
I don't think anyone would just use loose stuff, And one is often looking for more than simply undisturbed soil to sample - commonly an iron-rich orange layer just above that. Things like arsenic (a ggod indicator for gold) gets greatly enriched where there is iron. And you are usually trying to work this out with a hand auger, so you are not in a trench where you can see the relationship between layers - just trying to work it out based on what comes up on the auger blades. Because your samples are also spaced, even solil brought up in a fence-post hole can give a false positive or negative. And because of your sample spacing (often 100 m or 200 m between samples on regional lines), one false sample influences a significant length of line - perhaps the width of an orebody.Would it be simply surface soil sampling or sampling after the loose stuff is scaped back to an undisturbed layer? I think most of us here would know when we have reached undisturbed soil during our normal prospecting.
Have also seen linear sampling done using a ripper and samples taken of the ripped soil. But that was in shallow crown land on Sydenham Hill, Dunolly.
That is not actually old style loaming- which involved surface soil and panning (and yes, I was involved in this method that you describe at Fosterville). This involves digging down to a soil horizon enriched in certain elements and using modern analytical methods to analyse it. It may sound similar but it is much more effective - and often analysing elements like arsenic is more effective than gold in zeroing in on the gold.Have it from a Fosterville Goldmine worker that they use old style loaming (obviously in conjunction with other methods) to get quick economical sampling not just from roadsides but also farmers paddocks (permissions) and in the bush ......
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