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Post by 4wd on Jul 5, 2018 19:28:58 GMT
Old field boundaries showing up as greener stripes (clover) It's interesting how many of them are only typical garden size. These have never been seen let alone photographed before to my knowledge. Must try to look at more areas. I walked over it a few minutes later in slight disbelief, you can't see anything of it on the ground.
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Post by 4wd on Jul 24, 2018 16:12:58 GMT
This was taken last week just before showers started the grass recovery, you can barely see any of it now. The B&W conversion seems to smooth out distracting details.
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Post by 4wd on Aug 11, 2018 16:28:29 GMT
Today we have been doing electromagnetic survey which can produce something like a 3D image of what is below the surface. The main area of interest is the roundhouse enclosure. It took about 90 minutes but half of that was setting up and taking it apart. The machine costs in the region of £40,000! As you can see the field is now quite uniformly green but it was possible to roughly determine the place from the earlier photos. His opinion was that the place was chosen due to the shape of the hill behind which they would have felt 'did not just happen'. It is probably significant that on shortest day the sun just peeps above the slope on the left side and runs along it as it climbs from sunrise. After shortest day you can see it clear the hill again. In a time without calendars pre-Roman, this would have been important information for them.
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Post by rgsp on Aug 12, 2018 8:00:44 GMT
One of my lecturers as an undergraduate did the original work on wheeled downward pointing radar, in about 1970 to 1972. The first (and in many ways relatively easy) application for it was to find the rock profile under various glaciers in Greenland (though a sled was used there). I was all set to go on one of the Greenland expeditions, but got stopped by my lords and masters in Whitehall at the time. There isn't anything particularly expensive needed in the way of "bits", but it's a very specialised bit of kit, and I bet every one is just assembled by hand, and the figure of £40,000 for the cost sounds like a nominal figure to me, and well may be on the low side. I have been involved with tracing foundations and drains around one well-known cathedral, and similar radar does give some useful maps/patterns. Once the original survey is done, it can be extended and made more accurate by soil conductivity measurements (and a lot of computing) and after that actually digging holes to confirm the clever stuff!
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Post by 4wd on Aug 12, 2018 9:17:58 GMT
I think he was trying to give an overview of the equipment when for most of us it is almost incomprehensible how it works. Annoyingly I accidentally missed the record button at the start when he was talking about his first impressions of the site.
He does this more or less full time professionally and is often overseas with all this kit packed in a quite small car or taken on planes. It can be nightmare proving nothing is going to explode. Sometimes he has been forced to pay import taxes, basically it can e very difficult to explain what it is all for! The metal-looking cart is all some special resin which resembles fibre glass but it's not.
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Post by 4wd on Aug 12, 2018 16:56:34 GMT
The survey result has arrived, but it's quite disappointing. He says that is because the technique hasn't worked very well here, rather than because there isn't anything there. If you go squinty-eyed there does seem to be a circle and a half circle perhaps? The outer box is to determine what is the background magnetic field which varies according to underlying geology at each site.
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Post by Joyce on Aug 14, 2018 22:17:44 GMT
TV news report tonight about some presently visible ancient sites.
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