Hidcote: The Far North

Hoarfrost in 2010 along the trees which line the field containing the medieval building earthworks.

Recently, things have been happening in the far north – so- as the last hours of the decade fade away it is time to visit a place this blog hasn’t been to before.

Hidcote is the very last bit of Gloucestershire.

Looking across the border into Worcestershire at the north end of the Hidcote Estate. The rainbow crosses Meon Hill in the centre of the photo which is the local Iron Age hillfort.

Immediately across the National Trust’s Hidcote boundary lies Worcestershire and the Midlands.

It is still just within the Cotswolds but it is further north than Chipping Campden where the Cotswold Way begins (See CW1-CW8). Anyway, it takes 2.5 hours to drive there from southern Wiltshire so I usually need a good excuse to go.

The National Trust acquired Hidcote from Major Lawrence Johnston in 1948. By this time, Johnston had created a nationally significant Arts and Crafts inspired garden. He purchased Hidcote Bartrim in October 1907 and gradually created a series of extraordinary garden rooms…though there was a necessary gardening gap 1914-18.

It is the garden that visitors come to see but this is a landscape full of archaeology and in the last few weeks new things have been discovered.

Meg researched the Estate, walking the surrounding fields and plumbing the depths of the archives to complete the National Trust Historic Landscape and Archaeological Survey for the property in 2014. The sites she identified can be found by searching National Trust Heritage Records Online.

The long winter shadows ripple across the undulations of the common field farming system. This was one large arable field with villagers working scattered strips (the ridges) with their neighbours. I guess there were chats.. when they rested… as we do today.. down the allotment, over the garden fence. How did you cope with that late frost…too much rain… not enough…what happened to the summer this year?

The survey demonstrated that Hidcote has the very best classic medieval ridge and furrow in the whole of NT South West (granted these earthworks are more of a Midland thing).

Meg found that Hidcote was a settlement recorded in William I’s Domesday survey of 1086 so it had been occupied at least since the Saxon period (there is a Saxon charter which mentions Hidcote dated AD 716! …but its authenticity is disputed).

However, there are two Hidcotes. Hidcote Bartrim is the NT bit with Hidcote Boyce a kilometre down the valley to the south. In history they are often confused.

The stone buildings are likely to occupy ancient sites and a group of earthworks in a neighbouring field are probably medieval house foundations. This suggests that the village was once much larger and has declined in importance over time.

The Hill Barn at Hidcote

Fieldwalking in the 1990s, found many bits of debris including Roman pottery and this was collected and plotted onto maps.

This year Judith will write the Hidcote Conservation Managment Plan.She will weigh the entire property in the conservation balance and filter out its significances (in consultation of course).

Chris the General Manager asked what additional archaeological work could be commissioned to support the CMP.

LiDAR, Geophysical Survey and Building Analysis were suggested and this was agreed.

Soon we were walking across the large arable field south of the village with Professor Dyer where he talked through the results of the fieldwalking he had carried out 20 years earlier. He pointed out a couple of areas where there were particular concentrations of finds. Some pottery was prehistoric but most of the sherds were Romano British dating from the 1st to 4th centuries. He also found the rare Post-Roman grass-tempered wares near the stream in the centre of the field.

Later, we walked around the village with Ian the building specialist: the farmhouse; the cottages; the ranges of outbuildings. We examined the clues in the building fabric and discussed similarities and differences in style. The shells of the buildings may be several hundred years old but they have been modified over time. The village is now rather picturesque..like a film set, designed for something essentially English… adapted in an arts and crafts style..probably during Johnston’s time but possibly in the late 19th century.

We wandered down an alley and turned a corner and Ian spotted a complete single light window carved out of a block of stone and reused in a wall. Roman? he wondered….seemed unlikely.

People had suggested that the scatter of chipped and broken pottery in the field could be the result of kitchen waste….gathered somewhere else… then mixed with manure and scattered. Could there really be a villa or farmstead lurking beneath the ploughsoil? Perhaps our newly commissioned fieldwork will detect something there.

So… the LiDAR has been flown and the report will arrive in the next couple of months. The building analysis is about to start ….but… the geophysical survey is complete.

The field with the earthwork house platforms and the arable field to the south have been covered using magnetometry. Earth resistance takes longer and is more expensive to survey and therefore this was concentrated where archaeology showed up on the magnetometry or as undulations in the ground.

Martin, the geophysicist contacted me after the magnetometry survey. ‘The field is full of archaeology’ he said. The plot shows a tangled web of geophysical anomalies. There are all sorts of phases of activity going on.. and as one might expect…it is concentrated where Professor Dyer’s fieldwalking highlighted areas of Roman building debris and pottery.

Part of the survey plot of Hidcote carried out by Tigergeo. Earlier mainly Roman? enclosures and building remains have been cut across by the later medieval strip fields ‘ridge and furrow’ these linear ploughing strips are arranged in parallel blocks or ‘furlongs’ mainly crossing the image from top to bottom but the furlong strips top right run from left to right. For scale this magnetometry survey
plot is 250m wide

So Hidcote…in the far north, beyond the Cotswold Way, you are far more than a beautiful garden. Already elderly at the time of the Domesday Survey, you have revealed yourself to be a long favoured place to live….. soaked in archaeological deep time.

We await the LiDAR.

Dyrham LiDAR 2

Dyrham House from the statue of Neptune above the park.

Last time, I wrote about the way the aerial scanning of the ground from a plane can produce high resolution digital terrain models which can reveal patterns of faint earthworks. These are impossible to see through aerial photography or visually on the ground, even in low sunlight.

I also mentioned the way that tree cover could be filtered out to see just the ground surface beneath the trees.

LiDAR is short for Light Detection and Ranging and these digital images are best interpreted by comparing them with other layers of information.

Modern digital mapping allows different imaging sources to be superimposed and by using percentages of transparency, the chronology and phasing of earthworks revealed by LiDAR can be better understood.

I will do this by using the LiDAR that the National Trust commissioned for Dyrham Park. A property which lies between Bristol and Bath in South Gloucestershire.

The LiDAR survey of Dyrham Park. The site of the mansion and West Garden lies at the bottom of the valley centre left. The lines of old medieval open field strips can be seen middle right

Briefly, Dyrham is a landscape park occupying an amphitheathre of natural terrain with the great late 17th century mansion occupying the valley floor beside a medieval church. The church demonstrates that manor houses have occupied this favoured spot since the Domesday survey of 1086. Archaeological fieldwork has demonstrated that there has been significant Roman and prehistoric occupation at this location.

LiDAR plot zoomed in to central area of the park. The Old Lodge area middle right.

The LiDAR plot of the whole park shows that the deer park here was enclosed out of a medieval open field system and that no cultivation has taken place for over 400 years. The plough ridges, arable strips and furlongs remain from the last year of ploughing frozen in time.

The farm buildings in the centre of the park have structures dating to the later 18th and 19th centuries shown on the modern aerial photograph.

A modern air photo of the ‘Old Lodge’ farm buildings within the park

However, if you upload the LiDAR and fade out the photo you can see that the present buildings do not relate to earlier earthworks though there is a focal significance to the area in which the buildings stand.

Air photo faded to show LiDAR earthwork detail beneath

Notice the three broad linear features radiating out from this place, a little above where the present buildings stand. These must be quite old as these linears are cut across by trackways and other features.

A 17th century map shows an earlier lodge near this location. This was the keepers house built at the division between the rabbit warren to the upper left and the deer park to the right.

Another layer to be georeferenced and compared with the LiDAR would be a geophysical survey which would show how vague surface earthworks might relate to anomalies detected beneath the ground.

Another quick comparison would be to compare historic maps with the LiDAR. Here the 1921 edition of the Dyrham Ordnance Survey maps is made transparent above the LiDAR. Notice how the trackway heading from the buildings continues towards the top centre respects a large rectilinear earthwork but does not show what it is.

The next slide shows the 1892 OS map over the LiDAR. In less than 30 years the size of changes can be seen. The site of the aviary is not shown in 1921 and in 1892 the enclosures surrounding the farm buildings were more extensive.

So the basic data of the LiDAR provides a great insight into the historic earthworks of a piece of land but it takes time to test them against all available sources and sift out the potential information that might lie there.

The Stourhead LiDAR

Whatever next?

When Archaeology takes advantage of new techniques, whole new landscapes of information emerge.

One of the most exciting developments in recent years has been Light Detection and Ranging or LiDAR for short. Using a drone or an aircraft, pulsed light signals are sent using a laser. When linked to a scanner and a global position system (GPS), It can create an ultra-fine 3D record of the ground surface over wide areas.

The boundary of the National Trust’s Stourhead Estate in South Wiltshire. Whitesheet Hill is on the edge top right. Stourhead Park and mansion, garden, lake and Stourton village are lower centre. Park Hill Camp hillfort lies in woodland centre left.

In large surveys, millions of light points are plotted and tied to existing mapping with the GPS. Each point has its unique XYZ position… latitude, longitude and height above the datum level.

The total Stourhead survey area tilted slightly to show the contours covering roughly the same area as the map above. Whitesheet Hill on the right The hillfort faintly visible on the lower right hand edge. To the left, two valleys separate a ridge which has Park Hill Camp hillfort near the middle.

The Environment Agency has been using this technology for years and have made their data freely available. A quick visual link can be seen here https://houseprices.io/lab/lidar/map. This survey data was collected mainly to predict levels of flooding and consequently it tends to be concentrated along valleys and coasts. It has given good results but the detail tends to be at 1.0m resolution or in the better areas 0.5m. The best quality is 0.25m density of coverage.

There are still large gaps in the land area currently covered by LiDAR and therefore the National Trust is commissioning its own surveys at 0.25m.

In the South West, there are new surveys for the Bristol and North Somerset properties, the Bath and Dyrham properties and most recently the data has arrived for the Stourhead Estate in South Wiltshire. Bluesky collects the data and it is analysed by ArcHeritage who provide the baseline digital imagery in various forms as well as the core GPS files.Their report picks up many new sites which have now been uploaded onto the NT Historic Buildings Sites and Monuments Record. This is not the end: new archaeological sites can still be discovered by further manipulation of the data combined with other information sources.

The LiDAR data can be uploaded into the digital mapping system and then it can be overlaid as a layer on digitised historic maps, onto geophysical surveys and onto aerial photographs. It is so easy these days to zoom in an out of maps and also to fade one layer of information and then see another in direct relation to it.

Detail of Whitesheet Hill causewayed enclosure. Four round barrows can be seen along its bottom edge all with little dimples in the top where the owner of Stourhead Estate, Richard Colt Hoare, excavated them in he early 19th century. One at the lower left hand edge of the plot was cut by a chalk quarry in the 19th century. Close examination of the plot shows phases of trackways and faint embankments.

A great ability of LiDAR is to fell forests and woods (virtually) to see the ground surface beneath. Something impossible with air photography.

Imagine the light pulses from the aircraft like rain falling on the ground. Some will bounce off the tree tops (the first returns) but many will hit the ground below the tree canopy (the second returns). There are systems to filter out the first returns so that only the ground can be seen. It is why I always ask for surveys to be done in the winter when the leaves have fallen from the trees and the ground surface can be most clearly surveyed.

Park Hill Camp from the air surrounded by conifer plantations. In the last 10 years the National Trust has gradually removed the trees from the scheduled monument. The LiDAR defines the earthworks in a better way than can be seen by aerial photography when trees interrupt the view (see below)

Stourhead’s Park Hill Camp Iron Age hillfort has been covered in trees for many years making it difficult to see. Over a number of years, gradually, the National Trust has been clearing the woodland and bringing it back to grass. The LiDAR survey has enabled the ramparts and ditches to be clearly seen as well as showing its strategic position on the ridge top unimpeded by the conifer plantations that surround it.

The ramparts and ditches of Park Hill Camp Iron Age hillfort revealed by the LiDAR survey.

Another great thing: the LiDAR light point cloud is three dimensional and this enables a digital terrain model to be created. This can be viewed on its own or it is possible to drape aerial photographs and/or historic maps across it…as though the map or photograph has become a gigantic cloth thrown over the contours of the landscape. There is now the ability to screen- fly through the Stourhead landscape switching on or off other layers of information while weaving up the valleys or skimming over the hillfort ramparts.

Stourhead Lake (bottom) and the position of Park Hill Camp Iron Age hillfort clearly revealed on the ridge top between two valleys. This area is planted with trees and this vantage point of the fortification would not normally be appreciated.

During a bright winter day, low sunlight will traverse the landscape bringing different shadows in sharp relief and revealing new details. LiDAR analysis can introduce its own light source and the survey plot can be re-generated.. with the light source at any angle and direction. This shows up very faint archaeological earthworks when the light source is beamed from a particular direction.

The LiDAR survey shows the quality of surviving archaeology and reveals where conservation should be concentrated across the Stourhead Estate.

This image looks down to the arable land from the hillfort and causewayed enclosure on Whitesheet Hill. On the lower land, the earthworks have been almost levelled by modern ploughing but old quarries can be seen clustered, where stone outcrops on a low hill, and faint traces of prehistoric ‘celtic fields’ can be seen.

The Stourhead farmland, ploughed for many 100s of years, has lost much of its archaeology but the survey still shows traces of medieval and prehistoric agriculture and traces of buried enclosures suggesting settlement remains below the ploughsoil….(though much worn down buried pits and ditches will survive).

However, there is fine earthwork survival in Stouhead Park and on Whitesheet HIll.

The prehistoric earthworks on Whitesheet Hill show up very clearly: the Iron Age hillfort to the south, the Neolithic Causewayed enclosure in the middle and the other enclosure (also probably Neolithic) to the north and in between Late Bronze Age cross ridge dykes, Early Bronze Age round barrows and medieval pillow mounds all crossed by banks, trackways and quarries of various periods.

Whitesheet Hill: LiDAR shows the ramparts and ditches of the Iron Age hillfort (c.300BC) at the bottom. The three rectangles are modern reservoirs just east of the National Trust boundary. A cross-ridge dyke (c.1000 BC) divides the narrow downland ridge separating the hillfort from the Neolithic causewayed enclosure (c.3600BC) which has a Bronze Age round barrow (c.2000BC) built over its southern edge and across its north side runs the old cattle drove road from the the west towards Salisbury and then on to London. Further along the down to the north (the upper edge of the plot), is another faint enclosure (c.3000 BC) of similar size to the causewayed enclosure (this site has been ploughed in the 20th century but can be seen clearly on the LiDAR).

The parkland is a very precious survival. The ridge and furrow of medieval open field furlongs was fossilised when the park for the mansion house was created. This must have happened before 1722 which is the date of our earliest map of the park.

The 1722 Stourhead Estate map (Wiltshire and Swindon Record Office). The newly built Stourhead House is centre right. The north-east corner of the park is Spencers Mead. The strip fields and curving enclosure ditch shown on the LiDAR lie within this field and Slade Mead below. Buildings in red between these fields were demolished in the late 18th century, the building sites lie where there are earthworks shown on the LiDAR image below.

Near the Stourhead House and near the landscaped garden obelisk are two turbulent areas of earthworks, outside the areas of agriculture and therefore places already occupied ….before the open fields were created it seems.

One of these, east of the House, is likely to be the site of the medieval Stourton Castle..demolished when the present mansion was created in the early 18th century. The other area near the obelisk is a mystery… the LiDAR raises many new archaeological questions…. wonderful.

Next year the Cotswolds and Hidcote NT properties will have LiDAR We await the results with anticipation…what new Roman sites lies beneath Chedworth woods……

The site of the present Stourhead House is lower centre. The buildings show as triangles. Top right is the NE corner of the present park where a large oval enclosure (prehistoric?) underlies the regular furlong blocks of strip fields divided by trackways (this is just grass not visible on the ground). Centre right and NE of Stourhead House is an area of earthworks likely to be the site of the medieval Stourton Castle. At the left edge of the picture is another grouping of mixed earthworks, perhaps an early settlement to the right of the mound with the 18th century obelisk monument on it.