Windermere Reflections – Industrial Archaeology publication

Cover of the popular publication for the Windermere Reflections Project

The popular publication we produced for the Windermere Reflections project has now come back from the printers.  It will shortly be available to purchase directly from the Lake District National Park Authority. Whether you are interested in community archaeology, industrial archaeology or the history of Windermere and the wider Lake District in general it is worth having a look at.

The book concentrates on the surveys and excavation undertaken in the Windermere catchment over the last few years as part of a Heritage Lottery funded project. Themes covered in the publication include metal mines, slate quarries, bloomeries, fulling mills and woodland industries. There is even a picture of me on the back!

Hexacopter UAV and Agisoft used to survey spoil tips at Greenside Lead Mines

View down the valley overlooking Tip 1 and the lower working areas at Greenside Lead Mines

At the end of July we were commissioned by the Lake District National Park Authority to undertake topographic survey of the three large spoil tips at the extensive Greenside lead mining complex near Ullswater in the Lake District. Archaeologically the site is of national importance and is protected as a Scheduled Monument. Future management of the property necessitated the present detailed topographic survey in advance of engineering works to maintain the stability and structural integrity of the large spoil tips. The buildings beneath the spoil tips are currently used as hostel accommodation.

Tip 1 precariously sat above the youth hostel at Greenside Lead Mines

Normally such a detailed survey, requiring close contours for the extensive complex would take an inordinate amount of time to survey using traditional survey techniques such as Total Station or even differential GPS.  Over the last few years we have been developing more rapid and cost-effective survey capability using various unmanned aerial vehicles (UAV) to photograph archaeological sites, which is combined with Agisoft software to create 3D models and contours of sites.

Preparations for surveying Tip 3 at Greenside Lead Mines with the hexacopter UAV

Part of the site was surveyed and excavated in 2003-4 in advance to engineering works on Spoil Tip 2 using traditional survey methods, but whilst that took a week or so to undertake the present UAV survey took a day of flying and setting in survey control to cover the entire mine complex.

Surveying at Greenside Lead Mines with our hexacopter UAV

The site was visualised in Agisoft as a digital terrain model in both solid form and also with the aerial photography draped over the top. The data from this model was used to create detailed contours of the earthworks at various scales which could then be used when drawing up the site.

Isometric view up the valley at Greenside Lead Mines – screen capture of a solid texture model in Agisoft

Isometric view up the valley at Greenside Lead Mines – screen capture of a photo texture model in Agisoft

The complete site was also output as a single flattened scaled composite image which was then annotated in the field to add in the finer detail of archaeological structures and provide hatchures to the topographic survey.

Agisoft xy topographic plot of Greenside Lead Mines

The finalised site drawings, contours and survey detail were then compiled into a single CAD drawing for the entire complex and figures created showing both the entire complex and detailed ones of specific features in the complex.

Finished topographic survey of Greenside Lead Mines

Detail of the topographic survey between Tips 1 and 2 at Green side Lead Mines – no photo

Detail of the topographic survey between Tips 1 and 2 at Greenside Lead Mines

All done at Blelham Tarn, so many many thanks to everyone who helped out

All done and trenches backfilled

Friday was the final day out on site at the bloomery at Blelham Tarn so we finished backfilling and reinstating the trenches as well as doing the last bit of survey and drawing up of the earthworks. A massive thanks should go to all of the volunteers who have given their time to come out and explore the four bloomeries around Windermere. Thanks should also go to Jamie, Wilm and Andy at OA North, Ian at EAS Ltd, Jamie and the field rangers at the National Trust and John, Eleanor and Holly at the National Park for giving their professional guidance on site.

We will now try to get some interim descriptions of what we found in each of the trenches on this site, and then as the analysis of the results takes place we will keep you informed of what we have learned, in particular what dates come back from any radiocarbon samples.

Octacopter UAV survey at Blelham Tarn bloomery, Windermere

Aerial plan view of Blelham Tarn bloomery

Jamie returned to Blelham Tarn last weekend to undertake aerial survey on the site of the bloomery as no excavation was taking place. He used his octocopter, one of two  UAV we have at the company, to take multiple vertical images across the site. The north-western half of the site was covered in trees but the main area of the bloomery mound/platform where the four trenches were opened up was surveyed in full. From the photographs taken we were able to process them in Agisoft to create three outputs which will be really useful in trying to get an understanding of the subtle topography and earthworks for this site. First we have a flattened aerial plan view of the visible parts of the site which can be overlain on the survey data I took last week.

An oblique view of the 3D model of Blelham Tarn bloomery

Then we have the 3D contour model of the detailed topography of the site which we can spin around, zoom in and out of, and pick up fine detail from. The screenshot above shows the model with the photo layer draped on, the one below shows it as the solid 3D generated model. Again from these we can pick up subtle details of the site and surrounding topography, and also see the trenches, spoil heaps and turf stacks!

An oblique view of the solid 3D model of Blelham Tarn bloomery

Finally we can create close contours from the 3D model (these here are at 10cm intervals) which are overlain on the rough survey data we took last week – open the image below and zoom it to have a look. We found that the contours were very detailed for this particular site and were (obviously) better than ones generated from LiDAR data for the region, which at 1m accuracy really didn’t show much of the earthworks themselves, and were also offset slightly from the survey data. We have found that the Agisoft contours are better at depicting earthworks of discrete complex sites, whereas the LiDAR contours at 1m resolution are fine for broader areas and showing the surrounding natural topography.

Rough survey data of Blelham Tarn bloomery overlain with 10cm contours created in Agisoft

I will use all of this information tomorrow when we go back out to site with the volunteers to finish off and do annotated hatchure drawings of the bloomery.

 

Bring out the flags! – Topographic survey at Blelham Tarn bloomery

Bloomery excavation and survey at Blelham Tarn, Windermere

As the excavations have got underway and continued in earnest this week at Blelham Tarn, I have been there for several days in both sunshine and occasional heavy downpours undertaking detailed topographic survey of the site. When the survey is eventually drawn up it will complement both the excavations and geophysical survey results and will give us a really detailed picture of this complicated site.

Rough survey data and contours for the bloomery at Blelham Tarn, Windermere

Two days were spent investigating the field containing the bloomery mound(s), using survey flags to differentiate the edges of breaks of slope to each earthwork, and then recording them using either theodolite or total station. The rough survey data has been overlain onto contour data at 10cm intervals that was created using LiDAR data, in order to give the general natural topography surrounding the site. One day was spent recording a large dammed pond and water channel located on the hillside above the bloomery and a further day was spent doing basic walkover survey to identify sites in the wider landscape surrounding the bloomery field.

Surveying at Blelham Tarn bloomery, Windermere

The rough survey results still need to be drawn up in the field to create detailed hatchured plans of the archaeological features. Initial results have revealed that the core of the site consists of a small sub-rectangular building platform with a flattened slag mound to the west. The gap between these mounds is a relatively flat platform and would have been used as a working area, and it contains the two furnaces identified during the geophysical survey (location of magnetometry grid shown in orange). The first excavation trench (open trenches shown in pink) is located on the inner edge of this building platform and is set across a wheel pit that would have once held at least one water wheel to be used to power the bellows on one of the two furnaces.

There is a flat triangular working area located south of the bloomery which extends out into a bog. There is slight earthwork evidence for small dumps of slag/spoil on the area, and possibly the eastern edge of some type of building foundation (shown in the geophysics results). Two trenches will be opened in this area to investigate these features, as well as another trench which has been opened to record the tailrace running away from the wheel pit. There is no surface evidence for the tailrace as it was infilled with slag, although this is picked out beautifully on the geophysics results.

Upslope to the north of the bloomery there is a slight gully or remnants of a field boundary (not a headrace to the wheelpit) which has a further small slag heap set against it.  On the steep slope above the site there is a large dammed pond with an overflow channel on the west side. It is probable that the pond was once used to power the waterwheel at the bloomery site but there is no direct evidence for this. The pond was heavily modified with a new dam in the Victorian era when it was used for hunting purposes.

Rough survey data for the bloomery and reservoir dam at Blelham Tarn, Windermere

Initial geophysics results from three of the bloomery sites investigated around Windermere

Colour generated magnetometry plot of High Stott Park bloomery

Here are the initial survey results for the first three bloomery sites to be investigated by us around Windermere. The surveys were undertaken by volunteers who were given enthusiastic supervision by Ian Brooks from Engineering Archaeological Services Ltd.

High Stott Park bloomery had very little earthwork evidence at ground level and the test pitting had revealed slag deposits spread across the field. The magnetomery plot and coloured plot (north to the right) show at least one furnace site on the top left (SW) corner, which on the ground was adjacent to a mossy area of slag deposit. The furnace is shown on the colour plot as an extreme dipolar anomaly (small red blob with dark blue around it). On the right hand side of the plot (NW) there are other anomalies and a messy spread of background noise. It is probable that the bloomery slag mound survives best on this side of the site but the whole earthwork mound was levelled at some point, probably during landscaping of the wider grounds of the nearby farm. There is an edge to the spread slag material shown on the SE corner of the black and white plot and also a linear feature running roughly NNW/SSE.

Magnetometry plot of High Stott Park bloomery

The magnetometry at Cinder Nab (north roughly to top) picked up one definite furnace site, which was located on the SW edge of the well-defined earthworks of the slag mound. The dipolar anomaly for the furnace is shown with a black arrow on it. The rest of the material adjacent to is consists of readings from the slag mound itself. Other things to note are the background noise on the left (West) of the colour plot coming from the fence surrounding the tennis courts, and also the complete lack of results from the putative later kiln which was seen as an earthwork on the ground located  immediately NE of the bloomery mound.

Colour generated magnetometry plot of Cinder Nab bloomery

Magnetometry plot of Cinder Nab bloomery

Challenging conditions for the magnetometry survey on the bloomery at Ghyll Head, Windermere

The magnetometry survey at the Ghyll Head bloomery (north to top) was tightly constrained by the steep surrounding topography and dense vegetation cover. The interpretation of the site has come into question because of the features surrounding (and possibly masking) the bloomery mound as probably being associated with a later bobbin mill. Also Post-medieval period pottery and coal nodules were retrieved from the top surface of the slag mound.

Thankfully the geophysical survey results identified a single furnace located just below the main slag heap. The dipolar anomaly results for the furnace is depicted on the colour plot as a red blob almost completely surrounded by blue. This signal corresponds to a  small circular earthwork mound visible on the ground below the main slag mound. The rest of the results on the plot are related to the main slag mound. Interestingly there are no obvious results for features associated with the nearest building platform to the bloomery.

Colour generated magnetometry plot of Ghyll Head bloomery

The site at Ghyll Head still needs many questions answering regarding the relationship between the bloomery and surrounding features. Was the bloomery a simple medieval period version powered by hand bellows? Was it a later water powered site with waterwheel and buildings? or are the surrounding buildings associated with the bobbin mill?

Magnetometry plot of Ghyll Head bloomery

So what is next for these three bloomery sites? Well we will use the geophysical results and revisit each of them to retrieve secure dating samples to be processed for radiocarbon dating. I will also post the completed survey drawings for each of the bloomery sites as and when they are drawn up and overlay the geophyics results so they will all make a bit more sense to people who haven’t visited them in person. A special thanks should go to everyone who has helped both myself and Ian with the topographic and geophyical surveys over the last two weeks.

Blelham Tarn – The excavation starts

The geophysics results look great!

Windermere Reflections

Today was a fairly epic day at Blelham Tarn. We got the initial geophysics results back, which were spectacular, and on the back of that we were able to select an area for excavation and open a trench. The magnetometry survey had on the previous day extended over the area of the bloomery and was undertaken at a much higher resolution than had previously been undertaken and makes very exciting viewing.

The magnetometry survey in progress

The initial magnetometry results from Blelham Tarn

The long black linear feature on the right is the tail race, and  at the top of that is a square white feature, which must correspond with a wheel pit.   To the left of that are two circular, very highly magnetic, features, which we are interpreting as the furnaces.  To the left of the tail race is a large rectangular structure, which we are tentatively suggesting was…

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Survey of the bloomery site at Cinder Nab, Windermere

Cinder Nab bloomery, Windermere

The beginning of the week saw the completion of the topographic survey at the third of the four bloomery sites presently under investigation around Windermere. This site, at the aptly named Cinder Nab, is located adjacent to the shore on the south-west end of the lake and is a little distance to the south-east of Stott Park bobbin mill.

Surveying at Cinder Nab bloomery, Windermere

The monument, consisting of a large turf covered kidney-shaped mound of slag, along with its location adjacent to a body of water, is typical of the surviving elements found at medieval bloomery sites. The mound is in a very picturesque setting overlooking lake and it looked particularly lovely as it was covered in a dense carpet of bluebells interspersed with a smattering of cowslips.

Eroded section of slag deposits on the lake shore near Cinder Nab bloomery, Windermere

The mound was bounded by a slight linear bank on the west side and in the past was apparently contained within a small copse of woodland immediately on the shore of the lake. It is surrounded by several other features, including a pair of smaller spoil mounds and the foundations of a presumably much later kiln that has been inserted into the shore edge just to the side of the bloomery mound.

Foundations of a later kiln adjacent to Cinder Nab bloomery, Windermere

The lake shore immediately adjacent to the mound has been eroded back exposing nodules of slag onto the foreshore, including one rather large example. The eroded section was cleaned back and recorded, it revealed deposits of slag waste, burnt charcoal-filled deposits and burnt clay layers. Evidently material associated with the furnace at the bloomery, including waste slag, fuel and clay from the furnace structure itself were dumped on the lake edge.

Large piece of slag eroded out on the lake shore at Cinder Nab, Windermere

There was no obvious evidence for in-situ structural remains of a furnace in the exposed section and the furnace(s) must be elsewhere on the site, and as usual cannot be seen above ground. The site will now be subject to geophysical survey to identify the presence of any furnaces and any other possible evidence for sub-surface archaeological remains.

Recording the eroded section of slag deposits on the lake shore at Cinder Nab, Windermere

 

Drawing the slag mound at Cinder Nab bloomery, Windermere

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Slag exposed in test pitting at High Stott Park, Windermere

We have just set up a new blog at Oxford Archaeology North to encompass all of the investigations, (survey, geophysics and excavation) that will be undertaken on the four potential medieval bloomery sites located around Windermere in the coming few weeks. The project is being run in conjunction with The Lake District National Park and the National Trust.

http://windermerebloomeries.wordpress.com/

Survey and test pitting at High Stott Park bloomery, Windermere

Surveying at High Stott Park bloomery, Windermere

 We spent the Friday of last week surveying the second of the four potential medieval bloomery sites located around the lake that are to be investigated as part of the Windermere Reflections project. This particular site was at High Stott Park, and lay to the north of the Stott Park Bobbin mill, a popular visitor attraction in this part of the Lake District.

The low mounded area/spread of the bloomery at High Stott Park, Windermere

The site consists of a flat-topped but slightly mounded field located to the south of the farm at High Stott Park. There is no obviously defined slag mound to this site but the area has slag exposed in molehills across the area and within a small stream/drainage gully on the south side. It seems that the area may have been landscaped probably as gardens for the farmhouse and this could have spread out the slag spoil into a thin layer across the field. Equally the slag may have been brought from elsewhere and dumped within the field, but from above ground we can’t tell if this is so, or if there are any surviving furnaces associated with a medieval bloomery.

Breaking the turf on a grid of test pits at High Stott Park bloomer, Windermere

For this particular survey we set up a grid of shovel test pits across the site to check for the presences and concentration of slag surviving across the field. The results of this process revealed that slag was present across the entire field for at least 50mx30m. Concentrations of charcoal were present in places and burnt clay deposits were evident in the north of the field. The site will be subject to geophysical survey over the next few days so hopefully this will give us a better picture of what is going on at the site, to see  if there is any surviving evidence for furnaces associated with the slag material, and see if this is actually a real bloomery site.

Test pitting at High Stott Park bloomery, Windermere

Slag exposed in test pitting at High Stott Park, Windermere