Quest for knowledge

Graham Lee – Archaeological Officer

We recently commissioned additional high resolution LiDAR data (Light Detection and Ranging) for several areas of the North York Moors in partnership with Durham University who are currently involved in a long term research project on the coast. The data is collected by scanning the ground with beams of laser light. LiDAR data sees through vegetation and tree canopies which otherwise can obscure the view of the ground level to conventional air photography. For this commission we were particularly interested in areas of heather moorland.

Most publically available georeferenced LiDAR data in England comes from the Environment Agency. It is relatively low resolution, with data points collected at 1 metre or 50 centimetre intervals. The collected points enable the ground surface to be accurately mapped – the more points that are collected, the greater amount of detail that is recorded and revealed through 3-D representation. The newly collected data we now have is at 10 centimetre resolution which equates to about 90 data points per square metre. The amount of data means the ground topography can be perceived through relatively dense stands of vegetation, such as gorse.  For large expanses of the North York Moors which are covered in thick protective heather the idea is that this new data will help us to artificially see the archaeological earthworks beneath. It was this upland moorland plateau where prehistoric people lived and farmed and buried their dead.

As an archaeologist I am looking for human-made patterns in the landscape which represent different forms of earthworks created by human activity – either upstanding banks or ditches/hollows –which are visible in the data. Once noted, experience with data collected from aerial photographic survey allows these features to be interpreted. The interpretation is not necessarily conclusive – some more complex features will require a ground visit to collect further information before an interpretation can be firmed up. The features identified can then be incorporated within the National Park Authority’s Historic Environment Record (HER) which is the catalogue of our current archaeological knowledge. New and enhanced information which increases our understanding of archaeological landscapes is also very important for the protection and future management of archaeological sites.

Initial examination of the LiDAR data for Levisham Moor has greatly increased our knowledge of the complexity and extent of the prehistoric and medieval field systems as well as other sites that survive here. This means that individual sites – such as possible prehistoric hut circles, as well as the extent of field system remains – can be precisely located and mapped rather than just using a general area. This is a considerable advance in our knowledge which greatly simplifies the locating of sites on the ground within extensive areas of what can seem like featureless heather moorland.

Fig 1: Dundale Rigg, Levisham Moor – The LiDAR imagery shows up the subtle remains of earthwork banks of an earlier (?Prehistoric or ?Medieval) field system overlain by later ridge and furrow cultivation. Also visible is a Bronze Age round barrow (mapped as a tumulus) with a central disturbance from the 1930s and a trial excavation from 1962, and the faint curvilinear traces of what is thought to be a prehistoric hut circle towards the top left of the photo.

Fig 2: Horness Rigg, Levisham Moor – Remains of a probable Prehistoric field system. The enclosed platform at the southern end, which sits within rather than being overlain by the fields, has been dated by excavation to the Late Iron Age or Roman periods.

In the future new information supplied by the LiDAR survey will be used to aid and stimulate research into the history and development of Levisham Moor and other areas in the North York Moors, as well as informing management, presentation and interpretation. LiDAR does not remove the need to confirm details on the ground and there is always work to do to look for associated features that may not be visible on the LiDAR, but it is enormously helpful in the quest for increased archaeological knowledge.

Loving Levisham Estate: a personal view point

Rachel Pickering – Natural Environment Team Leader

Every day (when I am not at my desk) I take the dog for a walk past ‘the view point’ and every day I love it!  How could you not?

‘The view point’: view from Newton on Rawcliffe looking north east over Levisham Moor

My favourite version of the view is when the wisps of mist are still stuck to the trees in the valley even when the rest of the morning mist has long since left. I get to admire the landforms – Newtondale, the finest example of a glacial-lake overflow channel in England, carving through the striking two tiered moorland plateau. If I time it right I can hear and sometimes see a steam train chugging and tooting its way into Levisham Station down in the valley.

What makes this view extra special for me in particular is that it comprises part of Levisham Estate which I manage, alongside our Senior Ranger David Smith, for the National Park Authority. Between us we ensure that the Estate, which has been owned by the Authority since the 1970s, is managed for National Park purposes. As well as the stunning landscapes it boasts some outstanding wildlife habitats and a full range of archaeological curiousities including scheduled monuments.

It’s not just me that thinks its special. The majority of the Estate is designated as a Site of Special Scientific Interest (because of succession habitats, botany and geology), with the moorland also being designated as a Special Protection Area (because of merlin and golden plover populations) and a Special Area for Conservation (because of heathland habitats).

The majority of the Estate’s 3,358 acres are heather moorland but it actually includes a bit of everything. Here are a few of its gems:

Over the years we’ve been carrying out projects to conserve and improve the Estate. Here are a few examples of these:

Improvements to the moorland grazing regime via a traditional Countryside Stewardship Scheme (2003-2013) and continued through the current Higher Level Stewardship agreement with the Commoners (Levisham Moor is Common Land).

Hole of Horcum area in 2015 showing positive results of bracken control . Bracken has also been specifically controlled on areas of high archaeological value at Rhumbard Snout and Dundale.

Scrub control on wet grassland habitat at Station Field 2008.

Tree planting in the Hole of Horcum 2011 as part of the Slowing the Flow at Pickering partnership project.

Access improvements being shown to National Park Authority Members – pitched path in the Hole of Horcum 2013.
Levisham Moor and the Hole of Horcum Walk

The Estate is a great place for volunteers to get involved. Over the last few years 4,000 of the trees planted are thanks to our committed volunteers. It has also proved to be a useful place for our Apprentice teams to practice their newly learnt skills including heather burning, bracken and scrub control, and fencing.

The Levisham Estate is a big commitment and a rewarding place for many people, not just me.

Footnote
I confess that I am feeling rather reflective at the moment as a couple of colleagues who have been working at the Park for even longer than me (over 18 years) are about to leave. I grew up near to Levisham Estate and have seen the changes close up, over time. A few years ago the following photos of ‘the view point’ were included in the ‘Now and Then’ photographic exhibition at The Moors National Park Centre, Danby. It was rather strange, but striking, that on the day I went to take the ‘now’ photograph there just happened to be four walkers sat on the bench. They were fascinated to see the level of change to the landscape and fortunately were very happy to be slightly rearranged to replicate the ‘then’ photograph.

Slowing down

Taken mainly from the final report for the ‘Slowing the Flow’ Project

The ‘Slowing the flow’ project is now completed, ahead of approaching winter. The purpose of the project has been to reduce the risk and severity of flooding in Pickering and nearby Sinnington.

The approach has been to slow the flow of water from off the moors into Pickering Beck and the River Severn and subsequently down into the settlements below.

The last element has been the creation of a flood storage area at Newbridge, upstream of Pickering – a site to hold up, and so slow down, extreme flows of water. It can hold up to 120,000 m³.

The ‘Slowing the Flow’ project was one of a number of Defra pilot projects looking into reducing flood risk and impacts. The idea was to make the best use of natural processes by adapting land use and land management to slow down and delay the passage of water.

Phase 1 of the project concentrated on building up a working partnership including with the local community. The National Park Authority were heavily involved in Phase 1 of the project as a major landowner in the area. The National Park Authority owns Levisham Estate upstream of Pickering and a number of tributaries into Pickering Beck arise on the Estate’s moorland.

The land management work undertaken in the two sub-catchments included establishing no burn buffers along moorland watercourses to protect soils and retain vegetation, impeding moorland drains using heather bales to lessen erosion, constructing ‘woody debris dams’ which slow but don’t halt watercourse flow, creating riparian buffer zones in forestry, and large scale tree planting and long term woodland creation because trees prevent sediment runoff and hold and use more water than other habitats. Two timber bunds were also constructed in the River Severn catchment. 

 

 

 

 

 

Phase 1 (2009 – 2011) led to Phase 2 (2011 – 2015) which allowed for the implementation of the outstanding land management interventions planned. One of the lessons learned was that five to six years is a more effective time scale for delivering a demonstration project, especially one that includes persuading landowners to change land use. Another lesson is that the measures undertaken have to be at an effective scale – the bigger the contribution to flood protection required, the larger and/or more extensive the measures need to be at the catchment level to make a difference.  The use of smaller, more diffuse, storage features can collectively contribute a sizeable flood storage volume, depending on their design and management – however catchment level planning/modelling is needed to guide and achieve the optimum placement and combination.

The ‘Slowing the Flow’ project was led by Forest Research, and the partnership that made it happen included the Forestry Commission, the Environment Agency, Natural England, North Yorkshire County Council, Ryedale District Council, the North Yorkshire Moors Railway, Durham University, Pickering Town Council and Sinnington Parish Council and the local community including vital landowners, and us. The project was possible only because of this joined up and inclusive approach to flood, water and land use management. Another lesson from the project is that efforts to reduce flood risk via land management interventions can be accidentally counteracted by other activities in the same catchment.

Although the main purpose of the project was to lessen the risk of flooding in Pickering, and also the village of Sinnington, the methods used will provide added benefits to biodiversity and the wider ecosystems. The piloting of the practical demonstrative measures have allowed the sharing of good practice, knowledge and skill development (e.g. NYMNP Apprentices).

Some issues…

Concerns over the stability of ‘woody debris dams’ and the potential for debris to wash out and damage downstream structures need to  allayed by the construction methods that use slot trenches and bracing logs to attach the structures to the banksides.

Having a National Park – a designated landscape – in the north of the sub-catchments had implications for the siting and design of land management interventions. For instance from a National Park point of view there was a limit on how much tree planting could be/should be accommodated on the Levisham Estate because of the ecological value of the existing moorland habitats which are designated as a Site of Special Scientific Interest and in some places also a Special Protection Area/Special Area of Conservation.

Persuading people to create woodland can be difficult. The selection of Pickering Beck as a demonstration sub-catchment was partly because of the relatively high level of public land ownership e.g. National Park, Forestry Commission. In the future achieving the necessary sizeable level of change on privately owned land is likely to require greater financial incentives. The new, integrated, Countryside Stewardship scheme should help by providing grant for planting that provides benefits, including reducing flood risk and diffuse pollution.

Conclusions…

Land management measures can make a significant contribution to downstream flood alleviation. They vary in type, size, scale of operation and mode of action but are most effective in combination as part of a whole catchment approach to managing flood risk. More modelling and experience of actual flood peaks is required to better understand the cumulative effect of the measures. In view of the level of commitment and investment required, resources are best focused on small to medium sized catchments that can be expected to deliver large-scale changes in land use and/or management.

It is not suggested that the ‘Slowing the Flow’ project will prevent all flooding in the two sub-catchments, but it is anticipated that there will be less flooding. It has been suggested that the previous 25% chance of flooding in any given year in Pickering, has now been reduced to a 4% chance or less…

Woodland with added purpose

Michael Johnson – Conservation Graduate Trainee

Our National Park hosted a meeting for the Yorkshire Branch of the Royal Forestry Society on 19 May. The on-site meeting on the National Park Authority’s own Levisham Estate looked at previous and ongoing regeneration schemes on semi-natural and plantation woodland and their part in increasing biodiversity and the viability of the local woodland ecosystem* as a whole, including the slowing of run off by planting trees.

We started at the Hole of Horcum discussing the woodland regeneration of the southern slopes and passes where most of the new tree planting has taken place; there was much discussion as to the long term effects that bracken and other plants would invariably have upon the new tree saplings and whether or not differing types of management techniques and also tree guards/fencing would be beneficial in order to protect the growing trees from grazing livestock at this early stage.

The rest of the day was spent at Levisham Woods, where we looked at the various felling and natural regeneration works that had been carried out previously and discussed the long term future of the site. The Royal Forestry Society represents all sorts of interests involved with woodlands – commercial, professional, academic, conservation. The purpose of the Society is to promote active woodland management for the sake of sustainable woodlands rather than represent a single group or single point of view. When it came to Levisham Woods we considered the balance between commercial management of timber and the management of a woodland for public access, biodiversity benefits and its own intangible sense of place. 

The discussion wasn’t quite as dramatic as the weather – we dodged hail, rain, thunder and lightning and also enjoyed an odd sunny spell. We all shared ideas and if there was one outstanding lesson it was that there is rarely a right or wrong answer when it comes to land management.

*Ecosystems are a big thing in conservation at the moment – similar to biodiversity but also including none living elements such as water, air, soil – the concept links together the interactions between natural resources and their management which are ultimately essential for humans. For a better explanation see here.

Let out of the Office

Tom Stephenson – External Funding Officer

A week or so ago as part of my induction to the National Park Authority I accompanied Mark the Woodland Officer to plant oak trees at Keldgate on Levisham Estate. Part of the area was PAWS (Plantation on Ancient Woodland Site) and the conifers had previously been harvested. The aim is that the surviving woodland ground flora will spread now that the ground shading conifers have gone and with some tree planting and natural regeneration the site will become a semi natural woodland habitat again.

I made sure I came fully prepared with man-flu, a borrowed jacket (thanks Amy Thomas) and inappropriate trousers – as is to be expected for an office boy let lose in the field. After meeting the Rangers and Apprentices on site, we continued the previous good work of the National Park Volunteers by planting more new trees and so helping restore the wood to how it would have been centuries ago before the recent introduction of non-native conifers. Despite the early efforts of the rain, I had a great day learning about woodland conservation, watching the occasional steam train trundle by and generally putting the world to rights as we dug holes, planted saplings and hammered in stakes.

As the new External Funding Officer for the Authority my actual day job is going to be helping to identify and secure external funding to enable our ambitious conservation projects across the National Park…

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.

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 13^th 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.

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.

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.

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.

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.

Soggy moorland helping to stop soggy carpets

Rachel Pickering – Conservation Officer

I wish that my favourite view in the National Park was tucked away somewhere that nobody else knew about – but it isn’t.  Instead it’s one of our most photographed views – the Hole of Horcum within Levisham Estate. Not only is the view stunning but it has also proved to be a key location for landscape works towards the Slowing the Flow in Pickering project.

Work began on 8 January 2014 on the bund at Newbridge which will store flood waters upstream of Pickering. This work is a culmination of efforts by a number of partner organisations over the last few years to make changes to upstream land management to slow down the water running off the North York Moors and into Pickering Beck before it gets into Pickering town.  For the last three years the National Park Authority has been busy carrying out the following work on its own land at Levisham Estate.

Tree planting

• 8,500 trees have been planted since March 2011, mainly locally grown oaks.
• Nearly half of these trees have been planted by the National Park’s Volunteers.
• Forestry Commission grant was received for the majority of the planting, via the England Woodland Grant Scheme.

Wooden dams created

• 18 timber dams were created by the National Park Authority’s Modern Apprentices.

Moorland gully blocking

• The National Park Authority has spent £7,000 on partially blocking natural occurring moorland gullies with heather bales on various parts of the Estate.

Re-vegetation work

• Heather brash has been spread in the Hole of Horcum to aid re-vegetation after the previous years’ bracken control left areas of bare ground.

Footpath repair work

• An eroding footpath into the Hole of Horcum has recently been repaired with improved drainage that will slow down run off along the route.

Heather burning buffers

• A new Environmental Stewardship Scheme agreement on Levisham Moor includes 10m no-burn buffers alongside watercourses leaving the edges vegetated through out the year.

The hope is that with this type of beneficial land management established upstream of Pickering, along with the creation of the bund just to the north of the town, the chance of extreme flooding events will be lessened in the future.

Looking after Levisham Estate

Alex Cripps – Conservation Graduate Trainee

I recently carried out the Levisham Botanical Survey for this year with the help of Dawn Rothwell, our current Volunteer Service Assistant and a keen Volunteer herself, and Sam Lightfoot, LEADER Volunteer.

Levisham Estate is one of the very few areas in the North York Moors actually owned by the North York Moors National Park Authority. It’s just north of Pickering and the land holding is made up of c. 1,360 ha of moorland, woodland, and upland farmland..The overall aim of management on the Estate is to maximise the contribution of the Estate to National Park Purposes

The purpose of the annual Levisham Botanical survey is to ascertain if bracken/scrub encroachment and over grazing are still having a detrimental effect on sites which had been identified as being species rich and of high botanical interest in the past. The Survey has been carried out most years since 2006 and the results help inform us on further management, or suggest changes to the current management, in order to improve the botanical value of the sites.

Three specific exclosures (4m x 4m) have been set up in Levisham Bottoms, the Hole of Horcum and on Levisham Moor. The exclosures are monitored each year to compare species diversity within the exclosures where grazing is eliminated compared to the surrounding area where grazing continues.

Over the years since 2006 the areas outside the exclosures have greatly improved due to the change in grazing pressure on Levisham Estate. A balance is needed between over grazing/management and not enough management allowing scrub to build up at the expense of other habitats.

This year six additional sites were surveyed that hadn’t been monitored since 2007. These sites had previously had an indication of over grazing and bracken encroachment/shading. Some of these additional sites are still species rich but others are suffering from overgrazing, resulting in species being miniature in appearance. Some sites are under severe threat from bracken and gorse encroachment and have reduced in size since they were previously surveyed.

All in all however sites have greatly improved as a result of active management – bracken and scrub clearance – that has been carried out in the last few years. These sites, such as a species rich flush in the Hole of Horcum and a roadside flush near Levisham Station, are really special. A flush is an area of wet ground fed from ground water. Plant species such as Black bog-rush, Round-leaved sundew, Common butterwort, Bog pimpernel and Ragged robin have been found in good numbers. These areas are also attracting other species such as the Small pearl-bordered fritillary butterfly, Golden-ringed dragonfly and the Common lizard.