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‘I am looking for archaeological evidence [before I believe it]’ says field archaeologist Phil Harding during a  recently aired Time Team episode.

On a site where archaeological remains are suspected,  archaeologists go equipped with information ranging from maps, plans and sketches, to remote sensing technology , specialist expertise and experience, but none can guarantee the survival, location or form of  human activity until the ground is dug.

Archaeologists get a true and accurate picture of time and place by gathering the evidence in the ground to understand past activities. Deciding which ground and how much of it is a fundamental decision for most archaeological projects due to value, time and cost pressures.

In this case Phil was referring to archaeology being excavated at Castle Howard in Yorkshire.  I remember this site fondly as it was the second shoot that I ever did with TT.  It is memorable equally for the stunning location, the novelty of a film shoot and the archaeology.

Castle Howard

On the surface this was a no-brainer of a site. Still in the ownership of one family, the Howards, who had held the land since the early 1700’s, they were in possession of plans and maps dating back almost that long suggesting any archaeological evidence remaining in the ground should be easily found.

 The Domesday book (1085AD) records the site as a Viking village called ‘Hildreschelf’.  The Time Team were able to access descriptions of the people and the village.  Again, the various elements of the village should have been easy to locate.

But when it came time to put in the trenches that would find the archaeological evidence of the original settlement on the estate, it proves difficult. 

The Techniques

The geophysical survey team used resistivity (measuring differences in ground density) and magnetometry (measuring changes in ground magnetics) to see if they could see evidence of structures and features in their results.   But the results were inconclusive showing lots of noise in areas and multiple targets for investigation in others.

The maps, plans and sketches were drawn at different scales also generating multiple targets on the ground.

The landscape topography didn’t give many clues because it was clear that during the development of Castle Howard the site had been literally levelled removing many tell tale signs of evidence remaining beneath the ground.

Target 1

During a search for the original church the different techniques came up with different ‘best’ targets. And so Phil says….I want to see the ‘physical evidence’.

Geophysical survey offered 4 good looking responses.  One response with 2 straight lines and square angles, and a concentration of noise was chosen as a good choice for a trench.  The map evidence also suggested the church was in this general area, within 20m…which is pretty good for a lawn as big as Castle Howards. 

David Thorne one of the field archaeologists at the time opens the trench…hotly anticipating the results.  Finds dating to the right time period or a structure would have been good.

….But nothing.  Orange-brown sandy loam by the looks of it on our tv.  Not a hint of a cut, fill, masonry, artefacts, or a stratigraphic profile…the layers of time under the ground.

Target 2

In the walled garden, once a place for growing plants and fruits of warm climates, the search continued for the remains of the homes of Hildreschelf villagers.  It was thought the central road to the village extended into the walled garden and homes lined the road.  This meant that any remains of the Viking village would be found below under the layers associated with the post 1700 garden.

Geophysics suggested a wall may survive which acted as the first target, but much of the garden was full of ‘noise’ – a jumble of unreadable responses.  This was to be expected as the ground has been heavily disturbed as a tropical garden.  Heated piping was run under the earth to warm it and hence encourage growth of such fruits as pineapple.

Myself and Kerry Ely started the trench, removing garden soil to find an edge to a road, and the likely position of any remaining houses – and so I decided to extend the trench.

Underneath the geophysical survey noise was the base of a building, a straggly row of wooden stakes and evidence of a door.  All that survived was the very bottom of many features that were only just holding on in the earth by a few centimetres – all the evidence that was left of a family home.  The rest had been destroyed from above. 

The remains were so slight that the responses in the geophysical survey data had masked the remaining archaeological evidence, hence maps and careful excavation were needed to re-discover them, and prevent them from remaining lost.

Reasons for Trenches

Phil was right, there is nothing like excavation to establish once and for all if something exists.  You cannot rely on the documentary evidence or survey evidence alone. 

And this is the thing…

  1. Map scales and sketch plans are notorious for not translating well onto the actual ground.  There are big disparities between historic maps and actuality.  There wasn’t digital technology, satellites and lasers. There is inbuilt error to many historic documents using rulers, compass and pencil.  And the error increases with time as the maps are reused and translated. 
  2. Documents are often simplistic and the information can be biased to the creators perspective.  They may also reference physical elements that no longer exist.
  3. Modifications to the landscape and environment over time will either preserve or not the evidence of the past.  Massive changes to landscape occur with the laying out of large estates such as Castle Howard, taking away ‘lumps and bumps’, removing traces of previous uses and layouts.  As Mick Aston says at the episode end, this change was often used as a large stamp on the landscape to denote power and subjugation of a people.
  4. Geophysical survey has its own inbuilt set of problems.  A main one being:

It is not a magic tool. You cannot wave the equipment over or into the ground and selectively see only archaeology.  The technique is non-selective, in that it picks up built structures, internal features…AND, natural geology and geomorphology for example.  It can also mask evidence that only just remains in the grounds, and requires excavation more careful in nature.

For a large part its reliability as a tool for decision making in archaeology is only as good as the person analysing and interpreting the data being generated.

Belief in the Archaeological Evidence

Phil Harding is not alone in the opinion that it is necessary to see the archaeological evidence in the ground to confirm its existence.  On most sites it is the only sure way of establishing if the assessment, analysis and interpretation is correct. The expertise of a field archaeologist is to bring together all of the information that the ground retains, and produce interpretations and conclusions grounded in science and fact. 

Sometimes it is called ‘Ground Truthing’, and the sentence speaks for itself.