Following up on the surprisingly positive reaction to my post “Some facts to ponder about the march back to the Salient” I thought I would follow up with a similar article about photographs.
Back in 2000 I made a connection with a gentleman who was a retired RAF photo interpreter. His last posting, a Tornado reconnaissance squadron had as part of there training done quite a bit of photography of the English countryside. (alas those pictures he shared with me have been misplaced – RE)We had several interesting exchanges about the art of finding historical objects using aerial photography as a starting point. Unfortunately some of this conversation, and all the photographs which he provided have been misplaced over the years. So all I have left is this last little bit. However there may be some interest. And if I do find the rest in my “giant stack of papers” I will edit is and include them.
Again it must be remembered that these conversations happened 17 years ago. The explosion of technology has rendered much of this obsolete. However the average person who is interested in history will probably look at many more “normal” photographs than those taken using the advanced technologies. Perhaps the real value of Mr. Foleys comments is in the thought process.
“Dear David – thanks for yours.
I got to look at this after lunch today, when I came home from the gun club where I shoot on a Sunday morning. This week it was my turn to run the pistol side. There were only 5 of us this week (its summer holiday period over here for schools – started just Friday) and I was relegated to shooting my Ruger Old Army, and looking after the others who were shooting single shot percussion target pistols, two for competition targets. There was some serious shooting going on. Anyway, lets take a look at your last note so I can clear up a few things for you.
- IFRC (infa-red false colour) imagery can detect ground disturbance up to about 6 months to a year after the event, particularly if there was earth overlay involved. You get this effect because immediate sub-surface soil has different composition to that found deeper, even a couple of feet, which is why you can detect shallow graves and weapons hides so well (my thing in former Yugoslavia and Kosovo, I’m afraid) If you’ve ever dug a hole, you will notice that there always seems to be more to put back in than you dug out – this is due to the natural compression of the soil density, and is very difficult to simulate when you are back filling a hole you don’t want anyone to find afterwards, like a weapons hide or grave, for instance. After a longer period of time, such as the timescale you are looking at- 140-145 years, you have to rely on something else, and this is where the skill of the imagery analyst comes into play.
- Ordinary black and white or, even better, colour imagery, such as that taken for aerial survey work at a scale of about 1/10000 or better still 1/5000, will show what is termed differential growth effect, particularly over wide swards such as the average battlefield. If WE can see neolithic buildings dating from 2500 b.c., I’m sure you would be able to see your trench lines. The clues are as follows:-
- 1. Trenches and excavations show in grass or even in cereal crops as darker lines and outlines. This is because the ground water content of the soil is richer and more beneficial to the plant-life above it. So it grows higher, greener, denser and so on.
- 2. Walls and stonework subsurface shows up as the opposite of the above noted phenomena. Because of the parching of the soil above the sub-surface stone,rock, embrasure or whatever, the growth will be more meagre and show up as light toned outlines.
- We are really lucky over here as we have millions of sites to look at – especially after a dry summer with a bit of ground parching. When I was operations officer of 2 Sqn (a Tornado recce sqn) we found over 2500 new sites of possible interest in England alone, including a hitherto undiscovered Roman town the same size as Viraconium in Shropshire, and less than 5 miles away from it!
- I hope this gives you a bit of a better steer o your project, and yes, the excavation of WW2 aircraft crash sites occupies a lot of interest over here,indeed, over two years ago we found the final resting place of two B-17s that met in mid-air over a flat bit of Norfolk. Although the remains of the two crews had been buried in the US Air Force military cemetery at Madingley, near Cambridge, crash investigators were able, through close examination of the remains of the two aircraft that hadn’t been removed immediately after the crash, to re-enact the mid-air collisio by computer-generated imagery. If you forward me your address I would be more than happy to send you a copy of the documentary from our TV series Time-Team.
As for now regards.
That is a brief sample of the information regarding the study of aerial photographs I received in 2000. A shame that the rest of the correspondence hasn’t survived, but alas it hasn’t.
No matter, but since that time I have not looked at an aerial photo in quite the same way. There are so many things that they can tell us. Perhaps today in the age of LIDAR and drones we don’t think so, but we do so at the risk of overlooking important clues.