The ditch continues

Today we ran both the magnetometer and the GPR.  We have some problems ‘compensating’ the mag which may have been due to the geomagnetic storm which hit Earth at 9am BST but we still managed to survey a good number of grids.  We have one case of “frozen sensors” (see the lines near the top of today’s plot) but we can just redo a few lines and merge the data.

The magnetometer survey after day five.

The magnetometer survey after day five.

Two things stand out from today’s survey.  Firstly, the long sinuous ditch we first found on Wednesday continues, but with a curious dog-leg around a strongly magnetic feature.  Working out to which period this ditch belongs is going to be a challenge, but it doesn’t really seem to fit the town?  Answers on a postcard, please…

The second feature is the very strongly magnetic building on the westernmost edge of our survey.  It is aligned on the street grid, but is very magnetic.  Is it a building which burnt down?  Or perhaps it is something like a bath house?  Hard to say right now, but it is clearly a candidate for further investigation with GPR and/or resistance survey.

Talking of the other techniques, we managed a further 80x40m block of GPR data.  I’m going to look at that shortly.  We have also attempted further repairs to the cable of the resistance meter.  Fingers crossed we get good data with it next time.

The plan now is to work southwards until we hit the edge of the town.  The mystery of the sinuous ditch will have to wait a few days!


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