Time Team’s first GPR results surpass John Gater’s expectations
Geophysics on the Ness has come full circle with Dr John Gater back filming Time Team-sponsored surveys for a forthcoming programme.
A quarter of a century ago, John was commissioned by the UHI Archaeology Institute to undertake the initial surveys of the Heart of Neolithic Orkney World Heritage Site – the results of which suggested the presence of a large prehistoric complex on the Ness.
So it’s fitting that he’s back to carry out our final large-scale survey of the Ness – this time using ground penetrating radar (GPR).
John is accompanied by specialist Mike Langton, not to mention a highly impressive piece of GPR kit getting its first archaeological outing in Scotland.
Why are we carrying out more geophysics?
Primarily to complement the results of our recent resistivity and magnetometry surveys. These can be regarded as plans of underlying features – although they provide an good indication of what lies beneath, they are snapshots of multiple layers of archaeology as viewed from above.
GPR, which is considered the most accurate, highest resolution geophysical technology, produces 3d representations of subsurface features.
It works by sending energy pulses into the ground, recording the time it takes them to return and their strength. Deeper reflections take longer to return to the surface, allowing the depth of the feature to be assessed. A full GPR survey is made up of highly detailed “slices” that show the underlying archaeology at different depths up to two metres below the surface.
These “slices” are what we’re particularly excited about because they will, hopefully, help us clarify the development of the Ness complex over time – perhaps even different phases and structural changes.
By close of play today, Mike, assisted by Lucy, had surveyed the entirety of the south-eastern side of the site. That’s another of the delights of GPR – its speed!
Resistivity surveys take time. Our depth scans last month (the most detailed type) took over an hour for each 20-metre-square section. In comparison, GPR is blindingly fast – the kit attached to the rear of a quadbike that has been criss-crossing the south-eastern end of the site all day.
It’s safe to say that a viewing of some of the initial results saw sharp intakes of breath from the Ness team. We were expecting impressive. But not that impressive!
And John Gater was equally delighted – the detail and data from the completed section had, he said, surpassed his expectations.
The team are away back to Stromness now to process the results but will return tomorrow to survey the north-western end of the site, over and around Trenches P and J.
