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.

Neolithic and Roman Dyrham

It’s a fabulous piece of landscape between Bristol and Bath.

But you can’t really see Dyrham House at the moment it’s covered in scaffolding.

The west side of Dyrham House.Now covered in scaffolding while the roof is repaired. The medieval parish church beside it shows that there has been a house here at least since medieval times.

The west side of Dyrham House.Now covered in scaffolding while the roof is repaired. The medieval parish church beside it shows that there has been a house here at least since medieval times.

You can’t see Neolithic Dyrham either it’s covered in Roman Dyrham… and who’d have thought there was a Roman Dyrham. Paul found it a few years ago but he’s just found something 3000 years older.

The story we tell the visitors is that Dyrham is a great house and garden created by a wealthy man. A key player in William III’s government during the 1690s. That’s the most visible layer in the multiplex of Dyrham but it’s far too obvious and far too simple for the archaeological soul.

I got a text and decided to stop off on the way back from Brean Down. Parked at the top and walked down the bowl of the escarpment to the valley floor passing the scaffolded house to get to the West Garden.

I could see Paul’s trench at the far end and passed below the medieval church tower along the path to see what he had found. The gardeners want to recreate the late 17th century garden beds and the excavation was to find archaeological evidence for their location.

The view west along the access path towards the garden gate and to the left is the site of the excavation. It was dug to find the late 17th century garden beds but found something much older.

The view west along the access path towards the garden gate and to the left is the site of the excavation. It was dug to find the late 17th century garden beds but found something much older. The proposed sites for new garden beds can be seen as mown rectangles.

There wasn’t any really…but in the process Paul found a polished Neolithic axe made from stone brought all the way from south Wales. He also found some worked flint tools of the same date. He placed them on the table beside the trench. We wondered whether the 17th century gardeners had levelled the ground and cut down through the valley deposits reveal a Neolithic feature.

A polished axe made of stone from west Wales. It dates to the Neolithic period and is over 4500 years old.

A polished axe made of stone from south-west Wales. It dates to the Neolithic period and is over 4500 years old.

Things are not necessarily what they first seem. The next find from the feature was a piece of medieval pottery and then other things of various dates turned up..so the gardeners, 320 years ago, had dug up the Neolithic stuff from somewhere up-slope and then it became mixed with later material and dumped down slope to level out the garden terrace.

The gardeners’ redeposited soils were deepest at the south terrace edge. Mainly yellow and orange natural clay but then everything went dark again. There was still archaeology underneath. What could it be?

Then the Roman pottery started popping out of it, oyster shells and chunks of bone with cut and saw marks on, butchered joints of meat.

The pottery and bone from the Roman ditch filling.

The pottery and bone from the Roman ditch filling.

It went down and down.

It is good to imagine the generations who have enjoyed the gardens and then all those who lived here before the gardens. Lots to be discovered.. where are their houses now?

The view back towards the house showing the numbered archaeological layers filling the deep ditch filled with Roman pottery.

The view back towards the house showing the numbered archaeological layers filling the deep ditch filled with Roman pottery.

Describing Dyrham

Mr Newman once started his English class with a matchbox. ‘What’s this’ he said. ‘It’s a matchbox sir’ said Justin. At 12 it seemed a reasonable answer to me. ‘Call that a description !’ he shouted and threw the matchbox at Justin. That was the lesson. We struggled with increasingly complex descriptions and the matchbox kept sailing across the classroom. Even at the end, the names of the children of the match maker and the exact chemical components of each match head still remained a mystery. Great lesson though….

And what of Dyrham South Gloucestershire, above Bath, just south of the M4?

Dyrham from the east. placed on the floor of a natural amphitheatre. The statue of Neptune in the foreground is one of the few visible surviving elements of William Blathwayt's original garden for the house. The formal elements were swept away to create a landscaped Capability-Brown style park in the later 18th cenutury.

Dyrham from the east. placed on the floor of a natural amphitheatre. The statue of Neptune in the foreground is one of the few visible surviving elements of William Blathwayt’s original garden for the house. The formal elements were swept away to create a landscaped Capability-Brown style park in the later 18th cenutury.

It’s a Baroque stately home built from 1691 for William Blathwayt influential member of William III’s Civil Service who laid out an intricate formal water garden in the fashionable Dutch style. ‘Call that a description!’

Schloss Charlottenburg Berlin, built 1695 (while Dyrham was being constructed) built for Sophie Charlotte, wife of Frederick III Elector of Brandonberg. The gardens near the house are maintained in the style that Dyrham's formal gardens originally had.

Schloss Charlottenburg Berlin, built 1695 (while Dyrham was being constructed) built for Sophie Charlotte, wife of Frederick III Elector of Brandonberg. The gardens near the house are maintained in the style that Dyrham’s formal gardens originally had.

Archaeologists look beneath the surface, they interrogate the clues in the landscape and know that places are far more interesting than the obvious.

Dyrham House is placed on the floor of a natural amphitheatre. A stream flows under the house and emerges as a cascade feeding two lakes in the west garden. Such a well sheltered and watered location, someone must have worked out that this would be a fine place to live long before the 17th century. Of course they did. There’s the medieval parish church beside the house. There have been many Dyrhams.

The perspective view of the Durch style gardens at Dyrham in 1712. Our excavations and geophysical surveys have proved some of the features in the drawing and found other elements which demonstrate later changes to the 1712 formal layout. The statue of Neptune can be seen top centre above a water cascade that flowed into a canal in front of the orangery on the right hand side of the mansion.

The perspective view of the Durch style gardens at Dyrham in 1712. Our excavations and geophysical surveys have proved some of the features in the drawing and found other elements which demonstrate later changes to the 1712 formal layout. The statue of Neptune can be seen top centre above a water cascade that flowed into a canal in front of the orangery on the right hand side of the mansion.

William Blathwayt married an heiress and used his money to knock down the old Tudor manor and build his stylish new mansion. Dyrham is mentioned in Domesday book of 1086 and there is a document describing the medieval house in some detail in 1415. As there was no surviving male heir it was split between two Denys daughters Isabel and Margaret and every building and room in the manor was described and awarded to one or other of the girls.

There’s a drawing of William’s redesigned Dyrham dated 1712 and it shows how intricate the garden and park were at the time. At the top of the slope to the east was a statue of Neptune and from here a great cascade of water flowed down towards the house feeding a long canal beside intricately designed garden beds framing paths, fountains and avenues. To enable the water works, a dam was built out of sight of the house to build up a head of water which was then channeled to Neptune.

Too much to maintain.. and it became unfashionable, so the whole thing was swept away in favour of a landscape park in Capability Brown style in the later 18th century. Only Neptune remains.

The 1712 drawing by Johannes Kipp seems too much to believe but in 2001-2 we looked beneath the grass in the West Garden and there was the entrance to the inner gate and the pitched stone path leading towards the west entrance of the mansion.

A small trench in the middle of the lawn in the west garden discovered the  gateway to the inner garden and the pitched stone straight entrance track leading to it. Bottom right is the central socket for holding the ornate double-leaved gates in place. Top left is a raised metal fixing for holding a gate in place when open. One of the stones had been part of a window reused from an earlier house.

A small trench in the middle of the lawn in the west garden discovered the gateway to the inner garden and the pitched stone straight entrance track leading to it. Bottom right is the central socket for holding the ornate double-leaved gates in place. Top left is a raised metal fixing for holding a gate in place when open. One of the stones had been part of a window reused from an earlier house.

We measured out another small trench and found the massive foundation for a statue where Kipp shows that a stone sphynx had been built as an eye-catcher in front of the stable block on the south side of the mansion.

The trench in the lawn in front of Dyrham's stables.  This found the footing for the sphynx statue shown on the 1712 drawing.

The trench in the lawn in front of Dyrham’s stables. This found the footing for the sphynx statue shown on the 1712 drawing.

The medieval church, perched on the north valley slope shows that the valley floor has been greatly altered to create Blathwayt’s garden. What survived of the earlier Dyrham’s?

Beside the house is the medieval parish church. The late 17th century mansion is the lates of several re-designed Dyrhams that the church has witnessed. Cutting trenches in the lower garden reveal fragments of medieval cooking pot jutting out of the soil.

Beside the house is the medieval parish church. The late 17th century mansion is the lates of several re-designed Dyrhams that the church has witnessed. Cutting trenches in the lower garden reveal fragments of medieval cooking pot jutting out of the soil.

We cut a trench in the grass on the slope leading down to the lower garden and there found chunks of medieval cooking pot and animal bone jutting out of the slope. Blathwayt’s designers had cut away the natural curve of the valley to create level gardens and in doing so removed much of the earlier medieval evidence. The village probably once ran up to the church.

Looking north-west across the lower west garden where the stream that runs under the house emerges as a waterfall feeding two lakes before it leaves the garden and continues through Dyrham village.

Looking north-west across the lower west garden where the stream that runs under the house emerges as a waterfall feeding two lakes before it leaves the garden and continues through Dyrham village.

A few years later the lakes in the lower garden were repaired and new paths were constructed and at this level even earlier occupation was found. Remains of a ditch and walling with fragments of Roman pottery, oyster shells and animal bones in it. A couple of sherds of pot are typical of the pre-Roman Iron Age.

An excavation to repair the lake wall and put in new paths revealed pre-medieval ditches and stone structures.

An excavation to repair the lake wall and put in new paths revealed pre-medieval ditches and stone structures.

So Dyrham has always been a good place to live and people have adapted it over thousands of years..

Fragments of Roman and Iron Age pottery found beside the lake at the lowest level of the garden.

Fragments of Roman and Iron Age pottery found beside the lake at the lowest level of the garden.

It was also once a place of great strategic importance. The earliest reference to this place comes from the Anglo-Saxon Chronicle. In AD 577 (very rare to have a place named this early in British history) the West Saxon king Ceawlin won a great victory over the British kings of Gloucester, Cirencester and Bath. This drove a wedge and caused a permanent split between the surviving British strongholds of Devon and Cornwall and Wales…

We have never found remains of the battle here though we looked carefully when the new car park was built at the top of the hill in 1999. Perhaps the last stand was within the fortifications of Hinton Hill Iron Age hillfort on the north side of Dyrham Park.

There is a lot more to be discovered to properly describe Dyrham but that’s the great thing about archaeology.. the description is never completely complete.

Object of the Month – calling all gardeners

Another mystery object for you all, this time from the gardens at Dyrham. When working on another job at the property the gardeners asked if I could look at some of the things they had found when digging over the flower beds. In one box there were many of these long glass tubes.

One of the glass philes

One of the glass tubes filled with soil

They had been dug up from under a bush, and it looked like they had been put down in a pile next to the bush and forgotten about. They then had been buried over the years as fallen leaves turned to leaf mould and then, with the help of the worms, into soil.

They are roughly 26cm long and about 1cm wide, but each is slightly different in length, and width at the top and bottom. Most had broken ends, so it was not clear if they where meant to be closed or open, but we found one was intact. This had a hole at the end, so we can assume they all had.

A surviving end of the phile with rounded edges to the hole

A surviving end of the tube with rounded edges to the hole

The top has a flared rim, with rounded edges. As for age of the tubes we are not sure but they look like they are early 20th century.

Top of phile with flared rim

Top of the tube  with flared rim

I have asked our garden advisor if he has ever come across anything like them and what they may have been used for. He checked all his references and came across a reference to a ‘slender glass tube’ that was used for testing the water retention qualities of soil. You need to insert a porous bung into the bottom of the tube and then fill with soil; it is then inserted into the soil. Similar things can be seen in scientific equipment catalogues. Another idea is that they may have been used to feed plants directly to the root, or to water them. So, over to you all as I am sure you maybe able to solve this mystery, either with a new idea or to confirm our ideas 🙂