Diversions

I have been branching out of prehistory lately and following a number of temporary diversions from my research, so I thought I’d tell you about them. As part of my placement with the Yorkshire Dales National Park Authority I have been able to get out and about and help with geophysical surveys done by some of the local archaeological groups.

 

Members of Ingleborough Archaeology Group use a magnetometer to survey the site at Selside.

Fig. 1 Members of Ingleborough Archaeology Group use a magnetometer to survey the site at Selside.

A section of the Selside magnetometer data (approx. 20m x 18m). The strong black and white anomaly towards the bottom left corner marks the position of a suspected hearth. The data is displayed at +/-2.75nT, black is high.

Fig. 2 A section of the Selside magnetometer data (approx. 20m x 18m). The strong black and white anomaly towards the bottom left corner marks the position of a suspected hearth. The data is displayed at +/-2.75nT, black is positive.

The first of these was Ingleborough Archaeology Group, who have been investigating a site on the hillside above Selside, Ribblesdale, which consists of the remains of several stone walled structures. The geophysical survey was used to give an indication of what might be there and, alongside other considerations, guide excavation strategy. Although the remains of the walls were visible on the ground as earthworks and rocks, they don’t show up in the magnetometer data (fig. 2) – they are made of the local limestone and, aided and abetted by the thin soils, have next to no magnetic contrast with their surroundings. The magnetometer did, however, detect several magnetic anomalies that I interpreted as being caused by hearths or similar burning, so it was encouraging to hear that subsequent excavation has revealed possible hearths. Excavation turned up very few finds, although this in itself, along with an early medieval knife, means that current thinking places the structures in the Pre-Conquest period.

 

I have also been involved with Swaledale and Arkengarthdale Archaeology Group and their geophysical survey of Ellerton Abbey, a scheduled site near Marrick, in Swaledale. The site contains the remains of a small Cistercian nunnery, probably founded around 1200. Only the ruined church survives above ground now, and this was the focus of architectural, earthwork and geophysical surveys in 1997, which investigated evidence for the surrounding priory complex – you can read the report here. Adjacent to the nunnery lies an area of earthworks believed to reflect a deserted medieval village, while the gill and hillside above the abbey are suspected of being the location of a mill and water management system; these (the DMV and mill/watersource) have been the subject of the latest magnetometer survey. The data is now at a processing stage and it will be interesting to see how interpretation of this complex site unfolds.

 

The site of Bainbridge 'univallate hillfort'.

Fig. 3 The site of Bainbridge ‘univallate hillfort’.

Resistivity data from Bainbridge, covering an area 20 x 40m. Data is displayed at +/-1 standard deviation, so black shows areas of high resistance and white represents low resistance i.e. ditches.

Fig. 4 Resistivity data from Bainbridge, covering an area 20 x 40m. Data is displayed at +/-1 standard deviation, so black shows areas of high resistance and white represents low resistance i.e. ditches.

The third expedition came about as part of a geophysics training day that I ran at the YDNPA office for interested local archaeology groups. After a session in the classroom, we carted the magnetometer and earth resistance kit up a small, nearby hillock (fig. 3). This hillock, overlooking Bainbridge’s well-known and conspicuous Roman fort, has a wonderful view over Wensleydale, a convenient position beside the River Bain and a pronounced ditch and slight bank encircling the plateau on the top. Unfortunately for the purposes of geophysical survey, this plateau is bisected by a large dry-stone wall topped with wire fencing, and several mature trees. The site is referred to in the HER as a probable ‘univallate hillfort’, although it seems this is purely on the strength of the earthworks, so besides being convenient, the site was also of potential archaeological interest. The participants did a great job of surveying half the internal area of the enclosure… and found the encircling ditch showing up well in the earth resistance data (fig. 4), with nothing in the way of internal features in the magnetometer data. With any luck, the other half will be surveyed shortly, but in the meantime it looks like the best interpretation might be as a stock enclosure!

 

Part of the magnetometer data from Giggleswick. The suspected training trenches show up clearly as the pale zigzag (though there also appear to be some positive anomalies associated with the structure). Strong, discrete black and white anomalies indicate responses to ferrous sources. Data displayed at +/-5nT, black positive; area approx. 40 x 20m.

Fig. 5 Part of the magnetometer data from Giggleswick. The suspected training trenches show up clearly as the pale zigzag (though there also appear to be some positive anomalies associated with the structure). Strong, discrete black and white anomalies indicate responses to ferrous sources. Data displayed at +/-5nT, black positive; area approx. 40 x 20m.

Most recently, as part of the YDNPA Training and Trenches project, a survey of 2 suspected WWI training trenches was undertaken. The trenches, on the hillside overlooking Giggleswick School, Craven, may have been dug and used by the school’s Officer Training Corps. Alongside building survey of the Drill Hall at Settle, and earthwork survey of the firing range at Attermire Scar, the trench site was previously subjected to plane table survey by eager volunteers. Poor site conditions mean that the magnetometer data (fig. 5) isn’t as good as it could be, but it is certainly good enough to locate the suspected trenches – the well defined white zig-zags! It is interesting as, rather than having been backfilled with magnetically noisy rubble, they have been detected as less magnetic than the surrounding soil – perhaps containing wooden shoring or voids? Whereas in most archaeological geophysical surveys the strong ferrous signals (the discrete, black and white blobs!) would be considered as modern debris and therefore interference, in this situation they may well represent bits of the relevant archaeology that we are looking for. As part of the project, the trenches are being excavated in late June 2014, which will provide a great opportunity to compare the archaeological record with the geophysical results…DSC_1042 copy 2

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Up, up and away…

Aerial photographs are one of the most important sources available to archaeologists. Following the use of aircraft for military reconnaissance in WWI, the use of aerial photographs for other purposes – including spotting archaeology – really began to take off (so to speak).

 

One of the most important exponents of archaeological aerial photography was O.G.S. Crawford, who took a notably modern approach to the study of archaeology. Crawford was a contemporary of E. Curwen, who independently recognised the early field systems that Crawford referred to as ‘Celtic fields’. Importantly, Crawford was not just interested in ‘spotting old things for their own sake’, but in using aerial photographs to recognise and interpret patterns in the archaeology. In a 1923 lecture he demonstrated how he had used aerial photographs to accurately map the distribution of Celtic and Saxon settlements on Salisbury Plain; from this, he could show complex layers of occupation that were not visible on the ground, and indicate broader transitions that had taken place (Crawford 1923). The benefits of an ‘integrated’ approach is a recurring theme throughout Crawford’s work – long before it became a 21st century buzzword – and he regularly emphasized the use of aerial photography in conjunction with excavation and other sources.

 

The Yorkshire Dales National Park Authority has a comprehensive collection of aerial photographs that will help to define the extent, context and relationships of the coaxial field systems. But more on these at a later date…

The beginnings of aerial photography, however, go back before the use of aeroplanes, to the late 19th and early 20th centuries when kites of assorted designs were developed to carry camera rigs, to capture meteorological, archaeological and news reporting images, amongst other investigations. Kite Aerial Photography has been used since – see, for example, some fantastic pictures from the Scottish National Aerial Photography Scheme (SNAPS) here.

 

I was recently given a camera rig by the lovely people at SNAPS and have been attempting to do it justice. Unfortunately, the weather here has not been very cooperative lately (or breezy, which is hard to believe in the Yorkshire Dales), but I have managed to collect my first few pictures: they certainly suffer from the effect of the overcast sky, but they give an impression of the potential for providing detail and context for the prehistoric remains.

Field system near Conistone, looking towards Grassington. Coaxial boundaries are visible running down the slope from the left hand side of the photograph, either side of the modern boundary wall. © H. Brown.

Field system near Conistone, looking towards Grassington. Coaxial boundaries are visible running down the slope from the left hand side of the photograph, either side of the modern boundary wall. © H. Brown.

Near Conistone. Two coaxial boundaries cross the Dales Way footpath. The kite operator, walking along the tope edge of the photo, provides a sense of scale. © H. Brown.

Near Conistone. Two coaxial boundaries cross the Dales Way footpath. The kite operator, walking along the tope edge of the photo, provides a sense of scale. © H. Brown.

It turns out, sheep really like kites. © H. Brown.

It turns out, sheep really like kites. © H. Brown.

 

References

Crawford, O.G.S. 1923. Air survey and archaeology. Geographical Journal, May: 324-366.

Research trip: Céide Fields, Co. Mayo

Uncovered neolithic field wall at Cíede (with the visitor centre and North Atlantic in the background). © H. Brown

Uncovered neolithic field wall at Cíede (with the visitor centre and North Atlantic in the background). © H. Brown

In October 2013 I made a trip to County Mayo, northwest Ireland, ostensibly to visit friends, but also to visit the Céide Fields visitor centre. Céide has a wonderfully extensive landscape of prehistoric coaxial field systems, which has been preserved so effectively by several metres of peat and blanket bog that have developed on top of them. Field walls were first unearthed in the 1930s by the local school teacher, Patrick Caulfield, as he was digging peat in his garden in Belderrig, 7km west of Céide. Years later, his son, Seamus, went on to become an archaeologist (and eventually professor) and returned to investigate the Belderrig and Céide field systems (Caulfield 1978, 1998). Years of research ensued, which included tracing the lines of the field boundaries for kilometres under the peat by using an iron rod to probe the ground: when the metal rod is driven into the soft peat, the operator can feel whether or not there is a stone boundary at the bottom which can then be mapped to reveal walls, buildings and tombs.

Probing for field walls: the metal probe is used to detect their presence and the bamboo canes measure the depth of the peat. © H. Brown

Probing for field walls: the metal probe is used to detect their presence and the bamboo canes measure the depth of the peat. © H. Brown

Over the years more than a thousand hectares of fields have been traced in this way, revealing an expansive managed landscape. Radiocarbon and pollen dates obtained from materials across the site indicate that the field systems were already abandoned and covered in peat by 2500BC (Caulfield 1998) making them the earliest known field systems of this type in the world. The remains of the walls – which must contain many thousands of tons of stone – indicate a coherent and structured Neolithic society, with sufficient labour resources to clear woodland, divide up and maintain the land in an organised manner. The large area and extent of the fields suggest they were used for pastoral farming, although the team have discovered some early plough marks in the vicinity of settlement.

Roots of the c.5000 year-old scots pine preserved in peat, now taking pride of place in the visitors' centre. © H. Brown

Roots of the c.5000 year-old scots pine preserved in peat, now taking pride of place in the visitors’ centre. © H. Brown

All this is particularly interesting in the light of the Yorkshire Dales field systems, given that the Irish examples appear so similar in form yet date several thousand years earlier than the presumed date of their Bronze/Iron Age Yorkshire counterparts.

The arrangement of archaeology and visitors’ centre at Céide is fantastic – definitely a lesson in presenting ancient archaeological landscapes that could potentially be so uninspiring. The undertaking comes under the jurisdiction of the Office of Public Works and appears to be a success, attracting numerous visitors in a location where it is very difficult to be ‘just passing’. The centre itself is a striking pyramid cut into the blanket bog; inside, it is built around a large, gnarled scots pine tree trunk, around 5000 years old, that was preserved in the local peat.

One of the most notable aspects of the Céide visitor centre is the emphasis that is put on the field systems as a landscape, as opposed to just a site. This is underlined by the large proportion of the exhibition that is dedicated to the regional geology, geography and the local formation of peat and blanket bog. The exhibitions spiral up to the top of the building, where a viewing gallery (incorporating a glass-covered all-weather option – this is Ireland, after all) affords extensive views over the centre and beyond, placing the fields firmly in the context of the dramatic cliffs and expansive panoramas of the north Mayo coast. Definitely worth a visit!

References

Caulfield, S. 1978. Neolithic fields: the Irish evidence. In Bowen, HC & Fowler, PJ (eds) Early land allotment in the British Isles. A survey of recent work: 137-144. British Archaeological Reports 48. Oxford: Archaeopress.

 Caulfield, S. 1983 The Neolithic settlement of North Connaught. In Reeves-Smyth, T & Hammond, F (eds) Landscape Archaeology in Ireland: 195-215. British Archaeological Reports 116. Oxford: Archaeopress.

Caulfield, S., R. O’Donnell & P. Mitchell. 1998. 14C dating of a Neolithic field system at Céide fields, county Mayo, Ireland. Radiocarbon 40, 629-40.

© H. Brown

© H. Brown

Meet the Antiquarians

Antiquarians investigate prehistoric remains near Grassington. (Speight, 1900: 429).

Antiquarians investigate prehistoric remains near Grassington. (Speight, 1900: 429).

One of the first things I did for this project was to look at the earliest records of the archaeology of this area – those of the so-called antiquarians. The field systems around Grassington first hit the radar at the end of the 19th century, when it was a fashionable gentleman’s pastime to dig up local antiquities. Although their expeditions must have seemed ground breaking (ahem) at the time, their habits often prove frustrating to today’s archaeologists as the objects (and it nearly always was tangible objects rather than information) they sought were mostly treated as curios and taken out of context, or even lost, rather than being scientifically excavated and systematically archived according to modern standards.

Early finds from the Grassington Area. (Crowther 1930: xv)

Early finds from the Grassington Area. (Crowther 1930: xv)

In 1893 the Upper Wharfedale Excavation Committee was formed – with the patronage of the Duke of Devonshire, and the involvement of Professor Boyd Dawkins, alongside a number of pillars of local society – and affiliated to the Yorkshire Geological & Polytechnic Society. Although it was short lived (it was disbanded in 1895 when the chairman, E.E. Speight, moved to Oxford), the committee undertook a number of excavations of prehistoric features around Grassington. The Reverend B.J. Harker initially identified “quite a number of Druidical circles, dotted over the hills and pastures, with barrows and British forts…[and]…a supposed Roman camp of vast area” in the Grassington area (Harker 1892: 147) and it was noted that the valley sides between Kettlewell and Kilnsey contained “not a rood of ground without some evidence of ancient occupation” (Speight 1900: 427).

It is striking, though perhaps inevitable, that in most cases only minimal documentation and rudimentary descriptions relating to these studies exist: the success of these excavations was measured by the quantity and novelty value of skeletons and metal finds that the barrows yielded. Known undertakings include the opening of a cairn on Lea Green that contained 7 burials, the discovery of a twisted cord Bronze Age beaker, collection of numerous flint implements and the excavation and interpretation of extensive settlement remains; some of the finds are displayed at Craven Museum.

Curwen's map of Celtic cultivations at Grassington, published in Antiquity 1928.

Curwen’s map of Celtic cultivations at Grassington, published in Antiquity 1928.

Whereas interest in archaeology of the area was undoubtedly spurred on by the growing corpus of prehistoric finds from local caves – including, famously, Dowka Bottom (1863), Victoria (1875) and Elbolton Caves (1888) – it is notable that these individuals turned to the earthwork evidence for settlement for the first time, even if some of their interpretations (involving, for example, ‘Druid’s Circles’) seem somewhat out of date now. Standing in the 21st century, with its lidar data and sub-centimetre GPS measurement, the men in the black and white photographs, with starched collars and stern expressions, seem very distant. But at second glance, the work of some of these individuals is surprisingly recognisable to the modern eye. In the 1920s E. Curwen (an early pioneer of the study of fields) published his survey of field banks at Grassington, which involved careful systematic observation and comparison of features. This provides a landscape-context in which to place smaller-scale investigations and is extremely useful in a project investigating coaxial boundaries.

References

Crowther, J (1930) Silva Gars (Grass Wood) Grassington: Its history, antiquities, ancient footpaths, wild flowers and wild life, together with a guide to twenty-seven interesting walks in the district with map and illustrations. Grassington: Wadsworth & Co.

Curwen, E (1928) Ancient cultivations at Grassington, Yorkshire. Antiquity 2: 168-172.

Harker, BJ (1892) Discovery of Pre-historic remains at Grassington, in Craven, Yorkshire. The Antiquary. 26: 147-9.

Speight, EE (1895) Upper Wharfedale Exploration Committee. First annual report (1893). Proceedings of the Yorkshire Geological and Polytechnic Society 1891-1894 XII: 374-384.

Speight, H (1900) Upper Wharfedale. London, Elliot Stock.

© H. Brown

© H. Brown