Tag Archives: St Mary du Pre

The antepenultimate day (Part 5)

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

It was a very warm and sunny day today, and I think we all felt the heat.  We managed to complete quite a bit of work, though, and so congratulations to all the team.

The GPR team filled-in some of the missing bits on the west, north and east sides of the theatre field (Figure 1).  Just a few bits left now.

Figure 1: The almost-complete GPR survey.

One nice feature was a little detail found on the western side (Figure 2).

Figure 2: A detail of the GPR survey from today. The red arrow indicates a small building.

A nice little building is showing-up.  The block to the east may show some robbed buildings. Last year I noticed some curious white lines in that block which could be robbed walls.

The mag team completed an excellent eight grids taking their total area surveyed in four days to 5.09ha.  Frustratingly, however, I found that the sensors had frozen on the first three grid squares.  Horrible waste of time, but nothing to be done about it.  Figure 3 shows the whole survey.

Figure 3: the mag survey in Church Meadow after day 4.

Despite the frozen sensor, we can see some interesting details in the new area to the south (Figure 4).

Figure 4: the southern area of the mag survey in Church Meadow after day 4.

What I am finding curious is that the long linear features are white in the plots, i.e., below average magnetism.  The features look like ditches in form, but do not give the usually positive response one would expect from them.  My worry is land drains… but the features seem to connect with the edges of Watling Street.  How very curious.

Figure 5 shows the Earth Resistance survey after day 1.  The team completed an excellent eight grids.

Figure 5: the res survey in Church Meadow after day 1.

The broad dark line across the western corner is Watling Street.  Further east the various thinner dark lines are the walls of buildings.  Clearly we have parts of a number of structures showing clearly.  Great stuff.  We don’t have a cruciform-shaped building face east-west yet, but give us time.  Hopefully, tomorrow, we will cover the building which shows so clearly in the Google Earth image. Comparing the mag and the res shows how much the pipes obscure, and how they went right through the middle of this complex (Figure 6).

Figure 6: the res survey in Church Meadow after day 1, with the surrounding mag data.

Well it is now 1am, and I have to be up early in the morning for our penultimate day on site.  Many thanks to everyone who worked so hard in the heat today.

 

Mea culpa

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

Firstly, an apology to those to whom I said “no, we’ve done that” this afternoon when we hadn’t.  Oops.

Just a quick posting tonight as it is late.  The mag team completed an excellent nine grids in Church Meadow.  They are half-way along the field already (Figure 1).

Figure 1: the mag results in Church Meadow.

Sadly, the most obvious things are the two pipelines, and the dark stripes across one grid square.  The latter is our old friend the frozen sensor.  Way back during the survey in the Park we once managed twelve grids in a day only to have to re-do a bunch of them thanks to the sensor.  Of the archaeology, we cam most clearly see the edge of Watling Street heading SSE towards the Chester Gate.  The ditch we picked-up on Sunday appears to be the SW edge of an enclosure, possibly part of the nunnery.

The GPR crew managed an excellent five grids today despite only having one battery.  Figure 2 shows the entire GPR survey in the theatre field to date.

Figure 2: the GPR survey to date.

I’d like to give a big thank you to Jimmy Adcock of Guideline Geo for going above and beyond in finding a second battery for us as one of ours has died.  As can be seen from the figure, we are within spitting distance of finishing this field, and it would be a shame if we missed that target due to a dodgy battery.

The res team made it to the fence line. We would have finished the new transect if it wasn’t for my incompetence (see the opening paragraph!).  Figure 3 shows the res survey in the theatre field.

Figure 3: the resistance survey to date.

The funny little notch in the top by the fence is my little oppsie. Figure 4 shows the northern area with a high-pass filter applied to the new data.

Figure 4: the new area (high pass filtered).

The most obvious feature in the new data is the aqueduct showing as a very low resistance feature in white cutting across the transect.  There are, however, other buildings showing very subtly in the data that are very hard to pull out in an overall plot.  They show best in the thumbnails as one is putting together the data in TerraSurveyor.  Apart from the little partial which I’ll sort out tomorrow (actually, later today!), the Earth Resistance meter will move into Church Meadow tomorrow to try and retrieve a plan of St Mary du Pre denied the mag by the pipelines.

Just four days left!