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Author Topic: The Hoard Test.  (Read 836 times)
1morecoin
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« on: November 10, 2009, 10:06:40 PM »

Has anyone seen the Hoard Test on Gary's Detecting Site?, well this test has its flaws, firstly the soil was obviously very dry, the other problem with the test was the way they set the test up, they dug a 2 ft hole then excavated a channel into the side of the hole and put the coins into this side hole, then they backfilled the test hole.
Well firstly the coins would have had air pockets around them and obviously the air pocket above the coins,this is due to the soil not having enough time to fill in and compact the gaps, the idea of having compacted soil above the coins is ideal for the test, but the test is inconclusive if you have these air pockets.
I know that there is always a bit of exaggeration when it comes to the depth that we find some coins or artefact's at, but there is no harm meant by this,  after all with no tape measure it is sometimes difficult to judge depth.
2 ft deep is extreme for any discriminating machine on a smallish target, but we are talking about a large target or hoard here, this is far from impossible.
Now i am not saying that the guys who done the test were not doing it with the best intensions, far from it as they are very experienced detectorists and have a vast knowledge of detecting and use the best machines on the market, but this test is useless if the conditions are not correct, and you don't have all the facts about soil, moisture and the effect that airpockets have on the way that not only moisture travels through the soil but also how the frequencies that the detector sends into the ground can be effected by the same conditions.
Some of the Bronze Age Axes my friend and i found a few years back were at a measure 22 inches in permanent pasture which is obviously compacted and undisturbed, these were good two way signals and would have been picked up at a few inches deeper with no problem at all.
This depth was measured by the Archaeologists on site at the time, this depth is not far away from the 2ft target depth that the test was trying to prove or disprove.
Air pockets have a big impact on the depth that a detector can achieve and that is why most targets on ploughed land are retrieved from the top 12 inches max, with 7-9 inches being the norm due to light and fluffy soil, mineralisation also takes it toll on depth, this is not saying that you don't find larger targets deeper on ploughed land, i am just making the point that detectors will find targets deeper on settled land like pasture than on ploughed land.
The size and the metal content of the target also make a significant effect on the signal that you will get from a target, you will also get a stronger signal from a group of coins that has settled with the soil washed in to the gaps making the target one mass, than you would get from a loose group of coins regardless of whether the soil was compacted above the group.
I would be very surprised if the top machines that we all use from the Whites and Minelab stables didn't pick the target up with a good two way signal.
I will be looking into this in more detail and will get back to you with more evidence.

Steve.
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