Impacts of history

Graham Lee – Archaeology Officer

Further to my last blog post, here are some more examples of enthralling LiDAR imagery from the North York Moors. As mentioned previously, the interpretation of features is not necessarily straight-forward since we are not seeing a photograph per se  but a series of points joined together by a computer algorithm. A clear resemblance to ‘known’ features is a good start but often there is no substitute for checking the site on the ground where necessary, with the landowner’s permission.

Figure 1: Crag Cliff Wood near Grosmont

LiDAR - Cragg Cliff Wood, Grosmont. Copyright NYMNPA.

This image is from the 2016 This Exploited Land 25cm LiDAR (equating to c.16 data points per square metre). The This Exploited Land of Iron Landscape Parntership Scheme focuses on the 19th century ironstone industry in the North York Moors, one of the major sites for this was around Grosmont. This little four-fingered ‘hand’ near the centre of the image, just c.6.5m wide, is clearly a group of linear spoil tips leading out from a small excavation, perhaps a mining trial in the valley side? The linear runs of spoil, as tipped out of a barrow, are a very typical form associated with mining or quarrying sites. On steeper slopes, these are often tear-drop shaped.

Figures 2 and 2a: Rievaulx Village and the River Rye

LiDAR - Rievaulx. Copyright Environment Agency.

Aerial Photograph 2014 - Rievaulx. Copyright Get Mapping.

This image from the Environment Agency 50cm LiDAR (equating to c.9 data points per square metre) shows the site of Rievaulx Abbey (Scheduled Monument) near the central bottom of the picture, with all the buildings stripped away to show the underlying and surrounding earthworks. There is a mass of detail to see here. To the north of the Abbey are the houses of the village with a whole series of platforms and enclosures visible on the valley side. Just below these is the line of the “Canal”, a watercourse dug by the monks to bring a supply of water from the River Rye into the Abbey complex. Surrounding the village are numerous hollow-ways (former routeways) and extensive remains of old quarries. The level earthwork platform, running North-South to the bottom right of the picture is the northern half of Rievaulx Terrace. The corresponding aerial photograph from July 2014, with the water courses and major earthworks (mapped by the Ordnance Survey) layers switched on, help to clarify the positions of some of these features, including the line of ponds leading down to what was the Medieval water-mill, now a private dwelling.

Figures 3 and 3a: Holmes Alum Quarry in Mulgrave Woods

Aerial Photograph 2015 - Holmes Alum Works. Copyright Get Mapping.

LiDAR - Holmes Alum Works. Copyright Durham University/NYMNPA.

This is a classic example of the value of LiDAR imagery. The aerial photograph from August 2015 shows trees blanketing virtually all archaeological detail but this is beautifully clear in the 10cm resolution LiDAR image from Spring 2017 (Durham University/North York Moors National Park Authority; equating to c.90 data points per square metre). You can see the three adjoining quarry scoops to the south of Sandsend Beck, with a mass of, presumably associated, earthworks just across the beck to the north-west. This is thought to represent the site of Holmes Alum Quarry which is recorded as operating from about 1680. Works here had ceased by the late 18th century / early 19th century when this area was landscaped as an arboretum for Mulgrave Castle. I am not aware that this site has ever been surveyed in detail on the ground – this imagery provides a very good starting point. Roasted shale is recorded as having been found in the area so the sites of roasting clamps and, possibly, even steeping pits should probably be there to be found. On the plateau to the south of the quarries is an area of Medieval and Post-Medieval Ridge and Furrow (ploughing) cultivation which is clearly visible.

For more information on LiDAR, have a look at “The Light Fantastic” produced by Historic England

Understanding the past in the present

Graham Lee – Senior Archaeological Conservation Officer

Working in archaeology probably consists of a lot more desk work than most people imagine. There are site visits which are necessary from time to time in order to gain specific or detailed knowledge about a site – required for the provision of information or advice. Excavations are actually quite rare and generally undertaken by outside contractors since they are immensely time-consuming both in terms of the time on-site but more so in writing up the final report. Excavation also tends to destroy the features that are being investigated – so it tends to be an option of last resort.

So in terms of desk work one of the most important activities that we carry out is the maintenance and development of the archaeological index for the National Park area, on which we base most of our decisions and which we use to provide information and advice. Known as the Historic Environment Record (HER), this database contains summary information on all the archaeological knowledge that we hold. Presented graphically against a digital Ordnance Survey map background, this allows a very rapid assessment of the archaeological resource or potential of an area. Coupled with historic mapping and modern aerial photography, we have a very powerful tool to help us to understand the development and uses to which the North York Moors landscape has been put.

Below are a few examples to help demonstrate the range of information that exists within our HER.

Levisham Estate - boundary dyke

The first map (below) shows part of the Levisham Estate, which is owned and managed by the National Park Authority. The pink outline defines the area of the Scheduled Monument, the largest within the National Park, which has been designated (a process which confers legal protection) due to the archaeological importance of the range and survival of the archaeological sites it contains.

The National Park contains many moorland areas which have not been disturbed by recent agricultural activity and are consequently rich in prehistoric, and later, remains. The surviving sites on Levisham Moor illustrate the range of uses the land has been put to over thousands of years.

Areas on the map outlined in red or marked with the crossed-hammers icons represent records within the HER. Features plotted in black, with the exception of the mapped field boundaries, are earthworks recorded by the National Mapping Programme (NMP), undertaken for sections of the National Park area by Archaeological Research Services Ltd in partnership with English Heritage. The NMP pulls together existing aerial data and through analysis identifies features of interest. Activity over thousands of years is often clearer when viewed from the air rather than on the ground. On Levisham Moor particular attention has been drawn to the Bercary earthworks, a monastic sheep-farm dating from the 13th century, and the remains of a field system to their north-north-east which may be related. Away to the east of the central track there are a further series of enclosures and field systems – the enclosures which have been dated belong to the Romano-British period.

Levisham HER Blog

By adding our 2009 Geoperspectives aerial photographs as a backdrop (the most up to date aerial photos we currently have for the National Park), the way the archaeology fits within the landscape becomes much clearer.

Levisham HER Blog2

The third map (below) shows Rievaulx village and Abbey. As well as showing the data types mentioned above the map also includes designated Listed Buildings and designated Registered Parks and Gardens in blue, which indicate part of Rievaulx Terrace. The latter was laid out in c.1758 for Thomas Duncombe and linked to Duncombe Park by a picturesque carriage drive. The NMP plotted earthworks reveal evidence of the water management system around the mediaeval Abbey, as well as agricultural terraces, quarrying and even the faint outline of the monastery garden at the bottom centre of the image, just to the west of the pond.

Rievaulx HER Blog

Like I said, in the discipline of archaeology there is a lot of desk work to be done. The results – a better understanding of the impacts that people have left on the landscape over millennia and therefore a better understanding of the people themselves – are always going to be worthwhile.

Rievaulx Abbey by Jen Smith (NYMNPA)

The North York Moors HER is available to be viewed – but at the moment to see everything together, you’ll need to make an appointment and come along in person to the National Park Office because it’s not all accessible on-line. The information can also be supplied for an area on request, for a charge. However the national designations – Scheduled Monuments, Listed Buildings, Register of Parks and Gardens – are available to download from English Heritage.