Working in the rain

Anyone new to this blog or geophysics in archaeology is recommended to read the material on the “Geophysical survey in archaeology” page.

Today’s weather was “variable”, to put it mildly.  I ended-up with slightly sun burnt legs, but at lunch time we were shivering under a tree as the hailstones hammered down.  Nevertheless we got quite a bit done, and so many thanks to Dave, Anne, Ellen, Pauline, Mike, Jim, Nigel and Graham for persisting despite the dark clouds and the occasional flash of lightning and thunderclap (thankfully a long way off!).

Some surveys we get results where a great deal of squinting is required and some optimistic mental joining of dots is needed.  Today wasn’t one of those days!  Let us start with the Earth Resistance survey.  We decided it would be interesting to run the meter over the nice house on the hill for which we have mag and two GPR data sets.  The first image shows the magnetometry data from two years ago, the second today’s resistance data.

Fig. 1: the magnetometry data of the area with the “house on the hill”.

Fig. 2: the Earth Resistance data of the “house on the hill”.

The Earth Resistance data has been high-pass filtered to bring out the building nicely, but I think you’ll agree it is pretty clear.  It is interesting that the rooms on the western end of the house are showing much more clearly than they did in the GPR survey that we did two days ago (see this post).

Having wiped the GPR’s memory, we completed the grid square from yesterday and then managed another grid and three-quarters further south. Tomorrow we have to do the jaggedy bits along the edge of the field.  First of all, lets look at the mag data.

Fig. 3: the magnetometry data of the area covered by the GPR survey.

The strong linear feature running diagonally across the lower part of the image is the “1955” ditch, the 1st century boundary of the town which had a section cut across it by Sheppard Frere in 1955. The “house on the hill” can be seen in the middle towards the top.

Now for the GPR.

Fig. 4: the GPR survey at the end of day 3.

The grid below the house on the hill is mighty dull.  There is the faint building we saw yesterday, and one or two other possible features, but nothing too exciting.  The grid towards the bottom though shows as lovely town house facing SE.  The next image zooms in a little.

Fig. 5: the town house in the south of today’s GPR survey.

It looks like it lies on the road which runs along the inside of the 1955 ditch. Sweet!

The new software has a variety of palettes.  You have seen the BW one, and the default colour scheme No. 7.  The software can create a composite of all the palettes.

Fig. 6: a plethora of palettes.

Which do you prefer?  Answers on a postcard, please…

The weather forecast is better for tomorrow.  Fingers crossed!


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