Tag Archives: urban

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.

The mystery deepens

We managed to run all three machines today, although we were short handed on the resistance meter so many thanks to Peter and Ellen for soldiering-on. The unfortunate side-effect of the lovely weather is the top surface of the field is now like concrete!

First of all, the resistance results.

Day 27 resistance results.

Day 27 resistance results.

Day 27 resistance results, high pass filtered.

Day 27 resistance results, high pass filtered.

Not much new showing today, but we are getting a little more of the temple.  Tomorrow’s grids should show quite a bit more, if we can get the probes in the ground!

The GPR has, for the last few days, been working its way along the northern edge of the field in a series of stepped blocks.  With GPR it is not so easy to have a ragged edge.  Mike Smith, our expert GPR cart wrangler, felt sure they had found some stuff today.  Here are the last three days (the three blocks with jagged top edges) with today’s being the easternmost one.

GPR survey, days 25--27 (slices vary).

GPR survey, days 25–27 (slices vary).

Timeslice 3 (12.5 to 15.5ns) is usually a good starting place at this site.  Not much showing in that bottom block.  How about the next slice down?

GPR survey, days 25 to 27. Day 27 (the easternmost block with a jagged north edge), slice 4 (15.5 to 18.5 ns).

GPR survey, days 25 to 27. Day 27 (the easternmost block with a jagged north edge), slice 4 (15.5 to 18.5 ns).

I think Mike is right!  Excellent stuff.  Let us look a little closer at today’s block:

Detail showing day 27 results, 4th time slice (15.5 to 18.5 ns).

Detail showing day 27 results, 4th time slice (15.5 to 18.5 ns).

What is really interesting is not only do we have evidence of yet another building in the western side of today’s block, but the white lines surrounding darker areas on the eastern side suggest robbed walls of a large building.  Tomorrow’s results are going to be very interesting!

And to the topic of the TLA from the post earlier this evening.  Let us recap the story.  Last year we started picking-up a long ditch which ran right across the site.  It had been found in the two transects of mag undertaken by English Heritage in 2000, but at the time they were not linked. Last year we speculated that the ditch ran up the dry valley that the mag team have been laboring up and down the last few days.  On the 19th century maps there is a well marked on the other side of the Fosse field.  In the next image I have marked the line of the ditch.

The sinuous ditch.

The sinuous ditch.

Much to my surprise, the ditch curves around on itself at the western end, perhaps following the contours of the sides/bottom of the valley.  I will have to check that with the dGPS in the near future.  But where is it going?  Is it still an aqueduct as we thought, or something else entirely?

Looking more closely, we can see there are lots of other, smaller linear features in the area, some quite straight, and possibly even another building.  This top-corner of the field is proving very interesting and we will have to overlay the results on the topography to see what is happening.  This bit of the field is anything but flat!

Detail of the western end of the sinuous ditch.

Detail of the western end of the sinuous ditch.

Tomorrow we see the mag team edging closer to completing the Theatre Field, the GPR working along the northern edge towards the theatre and the the resistance meter covering more of the Insula XVI temple.

Another lovely day

Just a quick posting this evening to show the GPR and earth resistance survey results.  Firstly the GPR.  We completed another 80x40m block, shown here as the upper block in the centre of the image.

The GPR survey after day 21.

The GPR survey after day 21 (slice 4).

The lighter grey band running NW-SE across yesterday’s and today’s blocks is a road.  Either side of the road we can see the foundations of buildings.  They are a little scrappy, but they are clearly there.  What is really peculiar is the large round white feature, i.e., one with no reflections, in the top-left corner.  If we compare this to the mag survey we can see there is a large magnetic anomaly (shown as a dark, roughly circular, blob) in the same place.

The same area as the above image showing the mag data in the block surveyed by the GPR on day 21.

The same area as the above image showing the mag data in the block surveyed by the GPR on day 21.

Cuiriously, the round “blob” shows in the GPR data but the very strongly magnetic rectangular feature just to the south does not.  One can just make out the SW-NE running ditch in both surveys.  I have no idea what the large round feature is, but it is very large.

The team running the earth resistance meter did a sterling job completing five 20x20m squares.

The earth resistance survey after day 21.

The earth resistance survey after day 21.

As can be seen, the road in the SE corner is showing up very clearly.  Why is it so vague further to the NW?  I guess is may have been robbed.  In the top-rightmost square we are starting to pick-up the walls of the large complex building revealed by the GPR.

Tomorrow the GPR will do another block to the north, and the resistance meter will continue working eastwards.

As always, thanks to everyone who helped today.  More tomorrow.

 

Back to Gorhambury

When I woke at about 6am I could hear the pitter-pat of rain outside the window.  I groaned. Today was to see the start of the second season of work at Gorhambury.  Rain!  Just what we didn’t need.  I shouldn’t have worried as the rain soon stopped, and by midday the sun was out and the weather was warm.

My other worry was that a week ago we had no equipment.  The mag was being repaired, the GPR was somewhere in Oxford and the Institute of Archaeology’s nice new RM85 Resistance meter had yet to be delivered.  On Sunday we tested the mag… all seemed well.  Yesterday Ellen drove to Oxford to collect the GPR (she’s a star!), and UPS delivered the res kit.  Yay.  All ready to go.

We had a large team today consisting of a mixture of regular members and some new faces, mainly from the St Albans and Hertfordshire Architectural and Archaeological Society.  It was excellent to have such a large team allowing us to run all three instruments.  Many thanks to everyone who helped.

The new resistance meter has the ability to take two readings side-by-side, and does so very quickly.  I was very impressed with the first day we used it.  We managed five 20m x 20m squares at four readings per meter, even with a delay as we set it up.

The new resistance meter in action with St Albans Abbey in the background.

The new resistance meter in action with St Albans Abbey in the background.

We also completed eight 40m x 40m mag grids and two GPR grids, one 40 x 40m and one with a ragged edge.  The next image shows the mag survey of the entire town so far.

The town as surveyed so far.

The town as surveyed so far.

I’m starting to believe we might actually get the whole town, well the area available within the town, surveyed!  Zooming into the area we did today, we can see that we have picked up some more of the “1955 ditch”, the first-century boundary of the town first excavated by Frere in 1955.  It is the wide, straight dark linear feature which runs diagonally from the SW to the NE in the image below.

The area surveyed on day 19.

The area surveyed on day 19.

The annoying sensor-freeze struck again in the penultimate square.  Luckily it was only one line (the funny stripes are a result of the data processing) and we can re-do just that tiny bit and merge the data into the square in the software.  We mainly found ditches and pits (the dark blobs and lines), and are just getting to the busy area near the road.  There is a faint suggestion of a road behind the 1955 ditch, as we found in the southern area.

The resistance survey was a great success!  We did an area to the WSW of the theatre.

Location of the resistance survey.

Location of the resistance survey.

As I hoped, it picked up the road very clearly, but also picked up some of the details of the buildings.  The next two images show the resistance data and the mag data for comparison.

The resistance survey.

The resistance survey.

The mag survey for the same area as the previous image.

The mag survey for the same area as the previous image.

The GPR survey is just to the south of the res survey.  I have only processed the north block as it is too late to process the jagged-edged one too.  A number of walls and buildings are evident in the third and fourth time-slices.

Day 19 GPR survey, north block, slice 3 (14 to 18 ns).

Day 19 GPR survey, north block, slice 3 (14 to 18 ns).

Day 19 GPR survey, north block, slice 4 (18 to 22 ns).

Day 19 GPR survey, north block, slice 4 (18 to 22 ns).

The comparison with the resistance survey is also very interesting.  The GPR time-slices tend to show the walls better, but the resistance survey tends to show the road better.

Resistance survey overlain on the GPR and mag surveys.

Resistance survey overlain on the GPR and mag surveys.

GPR data from the same grids as the res survey in the previous image.

GPR data from the same grids as the res survey in the previous image.

Short and sweet posting this evening as we have another busy day tomorrow, but at least this gives you a feel for what we are now finding.