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

We may be creating our own digital data deluge, but today was the more traditional sort consisting of water falling from the sky. At midday the heavens opened and that was that. Another 10mm or so of rain. That makes over 20mm (or about an inch in old money) in the last 36 hours.

The GPR crew managed one 40x40m block before midday.  Figure 1 shows the time slices.

Figure 1: GPR time slices from day 8.

Sadly, nothing hugely exciting jumps out.  There are a few straight lines towards the NW corner which might be surviving walls, and the big blob just left of centre.  The blob is very curious.  It is quite persistent through the top slices.

Figure 2 shows one of the slices in context.

Figure 2: slice 5 in context.

This area is proving quite frustrating.  Lots of blobs and odd bits of straight line, but no clear buildings as we have had elsewhere.  Very curious.

I told the mag team to take everything with them, so I’ll report on their progress tomorrow.

Figure 3: the mag team work under a cloud.

Figure 4: the GPR crew at work.

Thankfully, the forecast is better for tomorrow, but damp again on Sunday. Many thanks to everyone who got a little wet today in the name of archaeological survey!  Your efforts are much appreciated.


Just two more days

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

I did consider using antepenultimate again, but I thought you might think me pretentious…

Everyone worked extremely hard today.  Mike and Jim on the GPR finished yesterday’s block and managed another 40x40m grid square.  No easy task over the long grass and thistles.  Ruth, Dave and Julia completed five earth resistance squares, including two that had to be done in two parts and joined together in the software later due to an inconvenient hedge!  Good job everybody, and many thanks.

Here is the Earth Resistance survey, both normal, high-pass filtered, and the magnetometry data from the same area.

Fig. 1: the Earth Resistance data at the end of day 16.

Fig. 2: the Earth Resistance data at the end of day 16, high pass filtered.

Fig. 3: the magnetometry data for the area shown in Figs. 1 and 2.

I hate to say it, but our five squares, including the two annoying partials, appear to lie between the buildings along the road to the north of the hedge line, and to the north of the buildings we found yesterday. We do, however, have a nice tidy area surveyed now.  We couldn’t have left quite such a silly hole in our survey data.  Tomorrow we head north to survey along the northern edge of the block we did last year.

The first block of GPR data from today was a continuation of yesterday’s

Fig. 4: the GPR time slices from the block completed on day 16.

Nothing very exciting jumps out from the plots, although there are some things to check out.  Slice 6 (second from top on left) has a strange upside-down M shaped feature (in black) and slice 8 (bottom-left) has something semi- or sub-circular near the northern edge.

How about the second block?

Fig. 5: the GPR time slices from the second block completed on Day 16.

Not a great deal there either.  Sorry guys!

Tomorrow sees the GPR crew filling-in an odd gap between last year’s survey and this years.  The plus side is that the mag shows lots of buildings, so tomorrow’s results ought to be much more interesting!

Many thanks to everyone who worked so hard in the sun today.  Just two more days.

Looking forward to 2016

Firstly, I’d like to wish all our readers, and especially all our volunteers, a very happy New Year and all the best for 2016.

This past year has been very productive with our big survey at Verulamium, but also other surveys around the region.  We have had an article published in issue 310 of Current Archaeologyand another article awaiting publication in the journal Archaeological Prospection,  as well as a short piece in the International Society for Archaeological Prospections newsletter.  I have given lectures about our work to the St Albans and Hertfordshire Architectural and Archaeological Society, the Römisch-Germanische Kommission in Frankfurt, the Norton Community Archaeology Group and to the Chess Valley Archaeological and Historical Society.  Several more bookings are in the pipeline.

One excellent addition to our work since August has been access to SEAHA’s Ground Penetrating Radar (GPR).  This has been an excellent addition to the range of techniques we can regularly employ on our surveys providing some superb results at Verulamium and Bushey Hall.  Hopefully, we can continue to access this machine in 2016, and perhaps even raise funds to purchase our own.

What does 2016 hold in store for us?  There are a number of sites which we are hoping to survey:


We are hoping to continue the survey of the Gorhambury estate side of the town in August.  We should be able to complete the mag survey of the Theatre Field and begin on the field to the north of the drive.  GPR surveys, perhaps resistance cart surveys, and even a magnetic susceptibility survey are all desirable as well providing we can access the equipment.

Willington (Bedfordshire)

We have been asked if we would be willing to undertake some surveys near the dovecot and stables at Willington, Bedfordshire.  The stables and the the dovecot are looked after by the National Trust and are listed buildings.  The area around them has been part of a community-based project for a few years looking for the Tudor manorial complex which goes with the standing buildings.

The dovecot at Willington.

The dovecot at Willington.

The stables at Willington.

The stables at Willington.

Hogshaw (Buckinghamshire)

Following our two successful days last February, it would be good to go back and finish the bits of the survey area we were unable to do last time, and perhaps try the GPR out over some of the areas where walls had been detected previously.

Surveying at Hogshaw.

Surveying at Hogshaw.


We have been asked if we would like to work with the Wing Heritage Group to do some surveys around this very important village with some great Anglo-Saxon archaeology.  It seems an exciting chance to try our equipment out on a different period of archaeology, and to work with a very active local group.


The Berkhamsted and District Archaeological Society have been working on the site at the Ashridge Management College for a few years.  They have asked if we would be willing to undertake surveys in the gardens.

Little Hadham

We undertook a survey at Little Hadham on a late Iron Age and Roman site a couple of years back.  The site merits more work to extend the survey.

Ashwell End

The site at Ashwell is like the road that goes for ever on.  It would be good to complete Great Buttway and move into nearby fields.

These are just some possibilities!  Hopefully I have remembered the main sites…  From a personal note I’d like to do some more work at Broom Hall Farm, and in the eastern half of the county more generally.  We seem to have been slowly drifting west!

Another aspect of our work also needs addressing, and that is writing-up the reports.  We need to develop ways to work on mapping the results of our surveys collaboratively, and to investigate archive materials, especially at Verulamium.  Help with drafting reports, again especially at Verulamium, is going to be needed.  All this makes me think that we probably need to put in for some more grant money to allow us to expand our equipment and software, and to develop ways of sharing the post-fieldwork analysis and reporting.

Last, but not least, up to now CAGG has only existed as an informal network based around our mailing list and the blog.  Should we be working towards creating a more formal group? Should planning and prioritizing surveys be placed in the hands of a steering committee? How to we maintain our identity of a cross-arch soc group, rather than being just another arch soc? Ideas and thoughts on a postcard to Kris!

I would like to thank everyone involved with our work.  Without you, there is no group and there are no surveys.  It has been a privilege to work with you all.

Here is to another successful year. May our anomalies be clear, our batteries charged and enthusiasm unwaning!



Today we ran the mag and the GPR on a warm, if not very sunny, day.  All went well, and we completed an area 80m by 160m with the mag, and 80m by 40m with the GPR.  All in all a good day’s work.  Many thanks to everyone who came out and helped.  The GPR results will take a little longer to process, but the mag data is looking great.

The mag survey after day 3.

The mag survey after day 3.

The temple in Insula XVI shows in the mag data quite nicely, if not very strongly.  We hope that the GPR and resistance surveys may show more details.  The line of buildings which runs SW to NE that we started to see on day 1 is showing very nicely.  Surely they must lie along a road?  Other buildings are also showing, and I have marked just one of them.  This is Monument 744 in the “Urban Archaeological Database”.  Just to the north is a long sinuous ditch.  We have about 65m of it so far.  The UAD only has 31m of it, recorded as Monument 740.  Unfortunately, both these monuments post-date the publication of Niblett and Thompson’s Alban’s Buried Towns so I am trying to find out some more information.

The weather forecast for tomorrow (Thursday) is looking grim, so we may not go out.  If so, I’ll work on the GPR data!  So far, however, the results are looking great.

Half way mark

As July draws to a close we have reached the half-way mark of the project.  We have bought the machine and run the course.  Even if we never surveyed another block in the Park, we have added significantly to what we know about Verulamium.  I now know more about the site at Six Acres and am looking forward to finishing the survey when the crop comes off.  The first site of several near Braughing has been completed.  Plans for surveying at Ashwell are advancing well, and we have agreement in principal for Wheathampstead.  Although the next couple of months are going to be extremely busy, I think we can be pleased with what what have achieved so far.

All this makes me think of the future.  What happens after the project has ended?  We are developing into a good group, and it would be a shame to lose that, even if people can still borrow the machine.  How can we collaborate?  Can we sustain the momentum we have built up?  Obviously there are many projects we could pursue: the rest of Verulamium, the landscape around Wheathampstead, the plethora of sites near Braughing, to name but three.  Having thought about this a fair bit lately, I wonder if a new group would be the best way to go? How about the Community Archaeology Geophysics Group or CAGG for short?  We could keep using this website, and we already having a mailing list.  Should we be just a virtual group, or should be have a formal membership? We can collaborate on surveys, or design and implement larger survey projects, we could share expertise and equipment, and perhaps meet now and again for mini-conferences looking at results etc.

Is this a good idea?  Is anyone prepared to run it at first? Would you all join? Let me know what you think.