Tuesday, 27 October 2015

Dean Crawford — Living among the Dobunni: more on fragmentation

This blog post is an image-rich display of the damage done by modern agriculture and is a necessary addendum to the post Fragmentation because it has come to my attention that some have misinterpreted the information to the point that one person even imagined that all damage was done in ancient times. Remember, too, that these are impromptu and/or "kitchen-table experiments" and not "hard-science" laboratory experiments. After all, archaeology, itself is not a hard science either. Let us call them "an aid to common sense". It is magical thinking to suppose that a field can be ploughed over several seasons without fragmenting metal objects highly crystalized after more than a thousand years in the ground. When I was a child, I frequently saw Roman coins with active (modern) corrosion lying on the surface of ploughed fields. I never collected any of these as most of them consisted, virtually, only of corrosion products. All images are by Dean Crawford and can be enlarged to see extra detail by clicking on them.

Dean noticed that a farmer had spilled some of his fertilizer in the farmyard and he gathered some of it to perform the experiment pictured above. It represents the effect of fertilizer in the field over a longer period of time but of course does not include the impact or pressure damage done by farm machinery.

Two English Medieval gold noble fragments
Dean found these two fragments of a gold noble three years apart and over thirty yards from each other in a ploughed field. The increase in deterioration can be clearly seen. The wear on such high carat gold is not due to the loss of material but due to the redistribution of gold molecules over the surface. If you think of spreading butter on bread you can get an idea of how this works. Soil particles "hammer" the gold. The fragmentation was caused by farming machinery.

 "Two more Dobunni coins, but the fresh fragments all found within ten to fifteen yards of each other, a few inches deep on ploughed land."
Dean Crawford

"Anglo-Saxon Great Square-Headed brooch fragments, all found over a thirty square yard area. Ninety percent of the brooch recovered, reconstructed and recorded". 
Dean Crawford 

John's Coydog Community page


  1. Hello John:

    It gets better by the edition. Brilliant. Love that brooch.

    The Council for British Archaeology's advice to leave objects in the ground for future generations (of archaeologists,no doubt!) despite the evidence of chemical degradation, and superbly illustrated by Dean, must be cause for concern. I expect 'Anonymous' thinks so too.

    I look forward to next edition.


    John Howland

    1. Thanks, John., The series is becoming very popular, indeed, Especially the issues of fragmentation and chemical degradation. I had first become enthused about metal-detecting in the mid-eighties because of the great numbers of new types of British Celtic coins that were being discovered. In 1989, Robert Van Arsdell had enough examples to completely revise the classification of all of the British tribes. Now that monumental book has gone online and further information is being revealed in this freely available second edition:


      But let's face it, Celtic numismatists are an enthused, but very small group of people. Dean is clearly demonstrating that the main area of concern is one of conservation: the rapid degradation of the evidence of the past. Now we will finally discover if the greater number of archaeologists are really concerned about the study of the past or are selfishly trying to possess it for themselves and no one else. I hope that readers of the series will also bring these concerns to their local politicians and the press. Everyone can make a real difference and that would be something to take great pride in doing. Who would not want their grandchildren and great grandchildren remembering them as conservationists?

      There is a lot, in this series, still to come!