Tag Archives: Watling Street

February fun

Partly as a training exercise for UCL students, and partly just to extend our surveys at Verulamium, members of CAGG were out in Verulamium Park and Abbey Orchard last Thursday and Friday.

The magnetometer was out in Abbey Orchard on Thursday in the hopes of completing that small area.  Unfortunately, I think it is jinxed.  On Thursday we had battery problems, and on Friday the odometer refused to work properly.  The sum total of a day and a half’s work?  Two partial grid squares…  Oh well, just chalk that one up to experience.  Here is the image of the slightly extended area, such as it is.

The Abbey Orchard survey.

The Abbey Orchard survey.

Having given-up in the mag, Jim West, Pauline Hey and I decided to use the Earth Resistance meter on Friday afternoon.  I had singled out an area where there is a clear building in the mag data, but some ferrous noise masked the western end of the building.  The weather was glorious for a mid-February day.

The Earth Resistance survey underway.

The Earth Resistance survey underway.

We managed four grid squares at the usual 0.5m spacing, not too bad for one afternoon’s work. As you can see in the next image, the mag survey shows a lovely building as white lines representing low magnetism.

The mag results in the area of the Earth Resistance survey.

The mag results in the area of the Earth Resistance survey.

The wide dark line coming from the SW corner is the ‘1955 ditch’, the first century boundary of the town first excavated by Frere in 1955.  The two parallel lighter lines which run just to the north of the building are part of a road.

Unfortunately, the Earth Resistance survey showed nothing of the building at all.

The Earth Resistance survey results.

The Earth Resistance survey results.

It shows the edge of the road beautifully, and a high-resistance feature parallel to the 1955 ditch.  Even the ditch itself shows as a wide band of low resistance.  Of the building, however, nothing!  It may be simply that the soil is so wet at the moment there is no contrast between the building and the surrounding soil matrix.  Alternatively, the building may have been robbed out.  We will have to run the GPR over it one day.

Unlike last November, the GPR suffered no glitches, and Mike Smith, John Dent and Graeme Spurway completed an area 160m by 40.  Added to the same sized area completed in November, we now have a nice block of GPR data 160m by 80m to look at.

The data were sliced using Larry Conyer’s system in 3ns slices.  I’ll go through these from the top down.  There are three areas of GPR survey shown.  The top half of the large block is the latest survey, the bottom half that undertaken last November.  The detached block to the west was undertaken by Ralph Potter in 2014.  Remember that this is a rather crude “mash-up” in Google Earth so the edges do not match very well.  As always the GPR data are deserving of a much more detailed analysis.

GPR slice 3, 10.5 to 13.5ns.

GPR slice 3, 10.5 to 13.5ns.

Slice 3 (above) mainly shows modern features surviving in the topsoil, especially broad cultivation marks running NNW–SSE across this field.  There are some hints of the archaeology just starting to show through.

GPR slice 4, 13.5 to 16.5ns.

GPR slice 4, 13.5 to 16.5ns.

Slice 4 clearly shows the upper levels of the archaeology.  Watling Street, which is running roughly north-south in the eastern half of the main area, has a big hole in it.  It has been severely robbed for building stone.  There is a minor road running SW-NE with a square building alongside it to the north with a small room on the western wall and what looks like a courtyard on the eastern side.

GPR slice 5, 16.5 to 19.5ns.

GPR slice 5, 16.5 to 19.5ns.

The main addition in slice 5 is the complex of buildings in the NW corner of the main area. These are probably associated with the pottery kiln which we have just clipped (the feature that looks like Mickey Mouse’s ears in the underlying mag data).

GPR slice 6, 19.5 to 22.5ns.

GPR slice 6, 19.5 to 22.5ns.

In slice 6, the spur road is clearer, especially near to Watling Street.  It looks as though there is a shallow valley running parallel to Watling Street which is now filled with a greater depth of topsoil which means that the archaeology does not show until the deeper slices.  It is also noticeable that the centre of Watling Street has fewer reflections than in the upper slices.  I guess that we are getting below the surface of the road, and the reflections either side of the road may be the ditches that Wheeler found filled with rubble.  The building complex just to the north of the spur road has hints of two more small buildings.

GPR slice 7, 22.5 to 25.5ns.

GPR slice 7, 22.5 to 25.5ns.

In this final slice we can see the two small buildings north of the spur road in more detail. There is also a long linear feature running N-S between Watling Street and the modern path.  It looks like a modern utility to me, but there isn’t one indicated on the map I have been given.

The GPR results are excellent, and it will be worth continuing to expand this area.

I’ve had a busy time speaking to various groups about CAGG’s work recently.  One of the lectures was as part of the Society of Antiquaries public engagement lecture series held on a Tuesday lunchtime once a month.  They video the talks and put them online, so if you would like to hear me talking about Verulamium once more, here is the link.

As always, many thanks to Ruth Halliwell, Peter Alley, Jim West, Mike Smith, Pauline Hey, John Dent,  and Graeme Spurway, as well as my students from UCL, for turning out in mid-February, although we were extremely lucky with the weather,

 

Rain didn’t stop play

… but may be it should have done!  Last year, on the last day of the survey, it poured and we cancelled.  Today, we thought “it is only a little drizzle!”  On occasions, drizzle was more of a deluge.  At one point I was about as far from the cars as it is possible to get when on site, and I got soaked.  Thankfully, Ellen went and fetched a dry tee-shirt and my waterproof coat.  Thank you Ellen, you’re a star!

Peter, one of our volunteers from SWHAS and WAS, has bought himself a UAV fitted with a camera.  He has been having some practice flights over the workers and the site.  When I have worked out how to edit the video down to a sane size, I’ll post one of those, but meanwhile here is one of the stills.  The UAV will prove a very useful tool.

Verulamium Theatre.

Verulamium Theatre.

One of the main reasons we persisted in the rain was the fact that we are so very close to completing the mag survey of the Macellum field.

The magnetometer survey of the Macellum field.

The magnetometer survey of the Macellum field.

Here is a closer detail of today’s survey.

The mag survey after day 36.

The mag survey after day 36.

As can be seen, Watling Street has rejoined the drive.  There appear to be many buildings opposite the theatre which isn’t a surprise in the heart of the town.  Street 24, which runs NNE from the theatre, has the macellum on the east side of it.  This building has been partially excavated and has a complex building history of five phases going from the mid-first century to the early fourth.  It has an almost equally complex excavation history: it has been examined by Grove Lowe (1847), John Harris (1869), Kathleen Kenyon (1934) and finally by Miss K. M. Richardson in 1938.

The resistance survey continued.  The wet surface was both a boon and a problem.  The first two grid squares went very smoothly.  Then we moved all the probes and so forth and the machine started to play-up.  After lunch, Peter came to the rescue and worked out that there was water where it oughtn’t to be, cleaned and dried connections and so forth, and all was well again.  We managed another three grids including one in 35 minutes.  Here is the survey.

The res survey after day 36.

The res survey after day 36.

The same area as the previous image showing the mag data.

The same area as the previous image showing the mag data.

In the first of the two images, I have not “edge matched” the grids so that you can see the ones which are a problem.  Three of the grids we did today fixed existing problems.  Although we had not planned to work tomorrow, I am hoping we might manage five more squares to fix the problems and give us a nice tidy survey.  Archaeological geophysicists are obsessed by “nice tidy surveys.”

Comparing the mag and the resistance surveys, the end of the “sinuous ditch”, seen snaking in from the top of the mag survey, can be seen in the resistance survey but it seems to continue further to the east.  The clear building on the northern edge of the resistance plot also shows pretty well in the mag survey.

Lastly, we learnt one lesson today.  The GPR doesn’t work well in the rain!  We surveyed a block near the rectangular enclosure I thought might be a temple.  Here is the mag:

Rectangular enclosure, near the southern side of the town, seen in the mag data.

Rectangular enclosure, near the southern side of the town, seen in the mag data.

Speculation has been rife as to what this may be, so we tried using the GPR.

Day 36 GPR data.

Day 36 GPR data.

The terrible striping is caused by the rain.  We will have to re-do this block another year.  We can see, however, a square in the centre of the block, and almost another square around it. Before we get too excited, however, comparison of the two surveys shows that the squares in the GPR data lie outside the NNE edge of the enclosure, and in fact, partly show as light white lines in the mag data.  Yet another question to be investigated more fully next year.

Many thanks to everyone who suffered the rain today.  You are all stars.

Tomorrow will be our last day.  I won’t post the results until Tuesday, however, as we are going for a celebration meal in a local pub.

Three day catch-up

I haven’t managed a Verulamium post for a few days so here is a quick catch-up.

Firstly, the mag has been slowly working its way eastwards along the Macellum Field.  They are getting pretty close to the end of it.

The mag survey in the Macellum field after day 35.

The mag survey in the Macellum field after day 35.

As can be seen, Watling Street stands out very clearly running from near the theatre to the Chester Gate.  There are lots of buildings along the road as would be expected.  Some are less clear than one would hope because they have been partially excavated.  The spec-ally look to the data, almost certainly because of the gravel subsoil, does make it harder to see what is going on here.  The carrot at the end of the stick — apart from just finishing the field of course — is that there are two Romano-Celtic temples known from aerial photographs near the modern road.

The next image is just to show how much of Verulamium we have now completed.  Poster, anyone?

The complete survey so far.

The complete survey so far.

The resistance survey has had a few problems.  The lack of rain has made the top-surface of the field very dry and hard.  It is very slow going, and the data is not as clean as one would like.  Despite the problems, however, some of the buildings along the road, especially at the north side of the plot, are very clear indeed.

The resistance survey after day 35.

The resistance survey after day 35.

Although it doesn’t jump out at one when just looking at the plot, the sinuous ditch does show in the resistance data when one knows where to look!

The GPR team completed some blocks along the hedgeline which I haven’t processed yet… sorry!  They also did one block up next to the Chester Gate to investigate the building here, and one over the sinuous ditch.  The latter did show the ditch but very little else.  Let’s look at the block near the Chester Gate.

The mag survey near the Chester Gate.

The mag survey near the Chester Gate.

This first image shows the mag data.  The building in the middle shows as white lines roughly parallel to the modern drive.  There are lots of other darker features, probably various pits and the sinuous ditch shows to the west.

Day 35 GPR, slice 2 (9.5 to 12.5ns).

Day 35 GPR, slice 2 (9.5 to 12.5ns).

This time slice shows the impact of splitting the survey over two days!  The left hand side was done yesterday afternoon, the right hand side this morning.  The pattern of the ploughing and the tractor’s turning circle in the corner of the field show clearly.  Luckily, the problem is much less acute at lower depths.

Day 35 GPR, slice 3 (12.5 to 15.5ns).

Day 35 GPR, slice 3 (12.5 to 15.5ns).

This time slice now shows the building beautifully.  What a wonky end wall on the north side! There is a long narrow range of rooms to the SW.

Day 35 GPR, slice 4 (15.5 to 18.5ns).

Day 35 GPR, slice 4 (15.5 to 18.5ns).

This time slice shows the SW line of rooms more clearly, although at the southern end they are been partly destroyed.  We can see, however, fainter traces of the walls on the NE, a corridor, perhaps?

Day 35 GPR, slice 5 (18.5 to 21.5ns).

Day 35 GPR, slice 5 (18.5 to 21.5ns).

This time slice does show the “corridor” to the NE much more clearly.  Perhaps it is more deeply buried in the plough bank?   For most of the plot, though, nothing much else is showing.

There has been a little rain this evening.  I have my fingers crossed for more.  Hopefully, tomorrow will be dry so that the mag can plough on eastwards!

As always, many thanks to everyone, especially those working with the res meter.  It is slow and boring at the best of times, but slow+annoying is a great deal to ask.

Record breaking

It was an odd day, weather wise. Largely dry with just one quick, light shower, windy at times, sunny spells… Luckily nothing interfered with the fieldwork!

The res team consisted of myself (when I wasn’t putting in grids for people), Ellen, Tim and Pauline.  They pulled out the stops and managed a record-breaking eight grid squares.  Area-wise, that is what the GPR covers in an average day, but for resistance survey at 0.5m intervals, that is very good going.  Well done everyone.

The resistance survey at the end of day 32.

The resistance survey at the end of day 32.

Today’s grids behaved themselves and make the four odd ones from yesterday stand-out even more.  I did make sure that some of the connectors were off the ground today.  How annoying. We may have to re-do those four grids.  The survey did, however, show the buildings along the road in the SE corner beautifully.  The big question… where now?  North to the sinuous ditch?  South for more shops?  West to cover the cross roads?  Only four days surveying left, and we have to assume that we won’t cover eight squares every day.

The mag team also had a very successful day in the Macellum field.

Detail of the mag survey showing the Macellum field.

Detail of the mag survey showing the Macellum field.

We can just see a hint of the cross-roads running NE-SW across Watling Street.  The ‘1955 ditch’ barely shows.  With the eye of faith one might see it in the high readings along the edge of the cross-road, but very much with the eye of faith.  Is the ditch just so built over we cannot see it?  Or was it never built here?

With just four survey days left to go, the team is getting close to finishing the field, but I think we are a day or two short of being able to do that.

The entire mag survey to date.

The entire mag survey to date.

Way down across the field, the GPR team tackled another fiddly staggered bit along the hedge line.  In the next three images I have made the previous days’ surveys partially transparent.

The day 32 GPR, slice 3 (12.5 to 15.5ns).

The day 32 GPR, slice 3 (12.5 to 15.5ns).

The day 32 GPR, slice 4 (15.5 to 18.5ns).

The day 32 GPR, slice 4 (15.5 to 18.5ns).

The day 32 GPR, slice 35 (18.5 to 21.5ns).

The day 32 GPR, slice 5 (18.5 to 21.5ns).

The curious shallow valley to the west of the surveyed area (‘valley’ seems a strong word for it!) that runs down the hill towards the temple is just as devoid of buildings or other recognizable archaeological features as the mag data.  In all three time slices not a great deal shows.  Was this valley always empty?  Or has the archaeology been eroded away, or even buried?  Difficult to say,  There is, however, a long narrow building just to the right of the middle of the surveyed area almost parallel with the hedgerow.  It seems fairly ephemeral, but it definitely there and one corner was picked-up in last year’s grid to the south.

Although the GPR hasn’t covered as much as the mag, we have still collected a mass of data.

Montage showing the area surveyed with the GPR to date.

Montage showing the area surveyed with the GPR to date.

It certainly takes-up a large chunk of my hard disk.

Many thanks to everyone who came out today and worked so hard.  A very successful day all round.  Our next survey day is on Thursday.

Watling Street

Firstly, apologies to those who turned-up and found themselves unemployed. With ground conditions difficult for the resistance meter, we just couldn’t run all three machines. Thank you for being so understanding.  Looks like it will rain most of tomorrow, so hopefully we can press-on with the resistance survey on Saturday.

The mag survey in the second field, which I am going to call the macellum field for convenience (it isn’t the field’s real name) is going well.  Firstly, an image of the whole town:

The mag survey of Verulamium.

The mag survey of Verulamium.

My long-held dream of having a complete survey of Verulamium is getting close to becoming a reality!  Thank you everyone.

Looking at the new area in more detail:

The area surveyed on days 29 and 30 in the macellum field.

The area surveyed on days 29 and 30 in the macellum field.

Hopefully, everyone can see the clear linear feature running from the SE to the NW.  This is Watling Street, the main road from London to Chester.  As one might expect just near to the gate (which was robbed and then excavated, and lies in the trees), there appear to be lots of little buildings along the road which show as white lines against the mid-grey background. What is more curious is the rather different look of that background: much less even and more noisy. I’m not sure why, yet.  The field certainly feels different: flatter, slightly different vegetation, and is obviously closer to the river.  Perhaps we have moved from chalk to the river gravels?  I must check the geology map…

The GPR has been doing lots of bitty blocks around the edge of last year’s survey area.  Rather than hold-up the posting of the mag data, I thought I would do the GPR later when I have dropped all the different areas on to Google Earth.

Thanks to everyone who helped today, especially Graeme for acting as my driver and go-fer as I limped around the field  (don’t ask!), and Ruth for helping transport all the equipment.

 

In the frozen north?

A short while ago we were in the bottom pointy bit of the theatre field. We are now in the top pointy bit! We have surveyed with the mag a substantial proportion of the field. A quick check with QGIS shows that we have surveyed 17.3 hectares of a 27.3 hectare field.  Good job everyone.

To start, let us see the overall progress.

The area surveyed after day 18.

The area surveyed after day 18.

The northern area has some very interesting features.

Detail of the northern area.

Detail of the northern area.

The sinuous ditch continues westwards up the dry valley towards the wall.  A basic aquaduct seems a good possibility.  Less Pont du Gard and more muddy ditch, as aquaducts in Britannia tended to be.  There are also quite a few small and quite faint ditches which look like small field boundaries.  Perhaps evidence of agriculture outside the town when the ‘1955 ditch’ was the boundary and before the wall was built?

There is a nice find in the topmost area.

A building parallel to the road just inside the Chester gate.

A building parallel to the road just inside the Chester gate.

A rectangular building can be seen a little back from the line of Watling Street just inside the Chester Gate.  Snack bar or tax office?  This will be a nice building to target with the GPR… next year!

On the subject of GPR, the crew managed a 20×40 block with the large 160mhz antenna, and two 40x40m  blocks with the usual 450mhz antenna.  Here are the time slices from the two blocks with the 450.

The more southerly block of GPR data. The slices are 8-12, 12-16, 16-20 and 20-24ns.

The more southerly block of GPR data. The slices are 8-12, 12-16, 16-20 and 20-24ns.

The more northerly block of GPR data. The slices are 8-12, 12-16, 16-20 and 20-24ns.

The more northerly block of GPR data. The slices are 8-12, 12-16, 16-20 and 20-24ns.

An excellent result showing a whole series of buildings.  Joining up the 16-20ns slices in Google Earth we can see how they relate to the magnetic data.

The day 18 GPR blocks overlaid on the magnetic data.

The day 18 GPR blocks overlaid on the magnetic data.

The same area as the previous image for comparison.

The same area as the previous image for comparison.

And finally for this evening, the context of those GPR blocks.

The GPR results around the day 18 data.

The GPR results around the day 18 data.

Quite an impressive series of buildings in the heart of the town.  Clearly, expanding the GPR survey next year will be well worth the effort.

The weather for tomorrow, our final day, is somewhat uncertain.  We will see…