I google'd Dankowski's name and found his website as well as the article you referred to. Very interesting reading.
In a nutshell, Tom D planned to do some detector testing on a beach and brought a womans wedding bad with a long thread attached so it wouldn't get lost. He set it on the wet sand and prepared to begin his testing. When he looked back for the ring, it was gone. Inspecting the thread, he found that within a couple minutes, the gold ring had sunk approx. 24" until it came to a firm base beneath the sand.
From this he suggests that when beach hunting look for areas of hardpan, where heavy items would come to rest, like gold being found on bedrock.
He does some additional testing with coils of various sizes at an inland location that has been undisturbed to the best of his knowledge for over 100 yrs. He begins searching a measured area with a small coil and working his way up to an 8" and then 10.5" coil, He hunts from 3 different directions with each coil. With the two smaller coils, he finds few coins, 2 for each coil at. When he uses the large coil, he finally finds a large number of coins, mostly from the 20's, at a depth of 10-11".
He observed that the coins are layered in depth by age of coin. Deeper he goes, the older the coins become. The bigger the coils he uses, the deeper he goes. After his testing, he returns his detector to the factory for unrelated repairs and when returned, finds that it not only has it been repaired, but fine tuned as well, getting an additional 2" of depth on a dime sized target. He returns to his measured area and finds even more coins, from the late 1800's at depths of 10-13".
He surmises that the sink rate of the coins has everything to do with soil density. In application, coins and jewelry will reach a depth of equalibrium where the density of the dirt surrounding the coin is the same as that of the coin. Surface area of the object must be taken into account as well.
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This example makes sense to me. If we want to answer the question of "How coins come to rest where they do?", I think we have the following variables:
1. weight and shape of object
2. density of the ground on which the object is lost.
3. wind and water erosion or deposition
4. accumulation of organic material (location dependant i.e. bare dirt, grass, forest floor, etc)
5. outside forces - digging or dumping of dirt, animals, insects, roots of vegetation,
6. freeze / thaw cycle.
Anything else that should be added?
Anybody care to chime in on the freeze / thaw cycle?
Rich (Utah)
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