Shallow is a relative term. Checking the gold nugget records of Vic cites many 'shallow' nuggets as being anywhere between the surface to 6 feet - the Welcome Stranger and hand of faith were both shallow, almost on the surface. Shallow usually refers to gold that was obtainable through shallow sinking, i.e. the common diggers holes we see through the goldfields. Deeper diggings were usually shafts and hence would be out of the range of modern detectors. Try and research the loaming process which means actively taking samples of soil usually above a known point where gold is located, usually alluvial. In a nut shell - its a means of working from Point A - smaller alluvial gold,back to the source point,usually a reef or variant thereof. A good place to check is where known shallow leads meet and research of nugget finds, and these are found on old original geologists maps, highlight that a lot were found at these junctions.
Indications of where the old timers have taken samples are posted elsewhere on the forum but are usually small, almost shovel like holes, dotted around the goldfields. These are normally found on shallow leads. Some times they were so successful that the whole surface has been taken away for processing, hence the term 'surfaced' or 'paddocked'. Areas around old surfaced areas are always a good start for detecting and sampling especially the edges where the old timers just stopped. Usually because the economic quantity stopped NOT the gold. Good gold for is still found around the edges of shallow workings especially around the sides of the gullies and higher ground.
Another loaming (sampling process) is to work up a gold bearing creek/gully and keep going until the gold either stops or gets very minute. That's when the process of working up from the creek begins - sampling (loaming) for the gold source. Yes, it can be very hit and miss. There is Sam Cash's booklet 'Loaming for Gold' which explains the sampling process you are after. There is no magic bullet. Some people even take away mullock heaps for sampling, especially on areas with smaller alluvial gold the old timers missed. Don't ever believe the nonsense that where the Chinese operated, they cleaned out the old mullock - I can assure you gold is still found on Chinese worked sites.
