Uncovering hidden glories
By John Pegg
A technology that is becoming increasingly popular allows us to understand far more about the history of sites than was previously possible.
In an age when the disturbing ubiquity of place and design response has become an alarming characteristic of globalisation, the British landscape remains a rich and multi-faceted canvas for landscape architects. The tightly woven fabric of a geological and cultural stratigraphy, etched and documented for centuries, provides a myriad of opportunities for the designer but comes with a deep responsibility to preservation and interpretation of the land itself.
This dual characteristic of drawing opportunity and responsibility in the design process from specific knowledge of the land has been at the core of most landscape architectural practices’ work, but the opportunity, pace of change and necessity for informed understanding are advancing at an alarming rate.
Remote sensing in its many guises has been an integral part of site understanding for decades, from poring over stereoscopic photosets to capturing the most recent satellite aerial photography. But today it is undergoing a revolution.
As a practice we have used text, historic mapping, geological evidence and aerial photography as tools in the field of archaeological prospecting. Work in the field has led us to the creation of public art, Radio 4 comedy and an ongoing engagement in the hunt for the site of the Battle of Watling Street. But now the nature of this type of study is changing rapidly and changing in a way that will impact significantly on how landscape master planning is undertaken.
Anyone professionally interested in the characteristics of land would have to have made a special effort to have missed the recent highly publicised work of Sarah Parcak of the University of Alabama at Birmingham. Dubbed by the media a ‘space archaeologist’, Parcak has enjoyed a high public profile, utilising satellite-based technologies of LIDAR and multispectral analysis to unpick complex archaeological sites from seemingly innocuous landscapes in Egypt and Canada.
Originating in the 1960s, as a military technology, LIDAR (Light Detection and Ranging) uses ultraviolet, visible or near infrared light to image objects. Working on this range of spectrums, the imaging is able to penetrate tree canopies to reveal the terrain, objects on the terrain and, significantly, minor anomalies in the terrain that would be invisible to the naked eye or other mapping techniques. These characteristics give LIDAR images the characteristics of aerial photographs on steroids.
2015 marked a revolution in the capacity of UK users to access data. In June 2015 Liz Truss, then the Environment Secretary, announced the release of a substantial number of Government-held data sets for free public use. These data sets included the Environment Agency’s 1m and 2m resolution LIDAR data sets. Whilst the coverage of the UK is incomplete, leaving frustrating holes in parts of the country, it is still significant. The year 2015 also corresponded with an exciting opportunity to use this new freely available data in a professional context on the master plan for Wicksteed Park.
Most British landscape architects who are serious about the development of parks and play will be aware of Wicksteed Park. The site where manufactured children’s play equipment made its global debut, it is also reckoned to be the earliest amusement park on mainland UK. The park, on the outskirts of Kettering, is undergoing a renaissance funded by its own commercial arm and the Heritage Lottery Fund. The core of the park dates from the 1920s but its wider boundaries encompass some classic English landscape typologies, recording more than 2000 years of history from an Iron Age settlement, through a classic medieval manorial settlement and a Repton Red Book to a Second World War garrison.
Faced with preparing a large scale landscape master planning project there were obvious concerns that the development of the landscape should not compromise historic landscape features, including those as yet unknown and unrecorded. After exhausting the traditional sources of site information, maps, photographs and aerial images, we commissioned a series of Lidar maps from geophysics consultant, BandaArc Geophysics. The team at BandaArc used the available Environment Agency data to create a number of plans and the results were astounding.
Far from merely identifying simple areas to avoid due to archaeological risk, the images threw the park’s topography and unknown archaeology into clear relief.
At a broad scale, the image above demonstrates how the data reinforced the site’s position as a bridging location.
The image of the known fortified manor site provided a great deal more resolution. Mapped and documented elements were augmented with a number of previously unknown features. Tantalisingly, this includes a set of apparent annex features suggesting what had been previously described as a fishpond complex might be a second fortification pre-dating the fortifications licenced to Nicholas De Seagrave, the Marshal of England in 1310 AD.
In 1794 Repton created a Red Book for a section of the park which has been subsequently dubbed the Repton Park. However the evidence of the Lidar image shown overleaf dispels the idea that Repton’s principles were followed in any meaningful way. One of the most-eye catching features, unknown from any previous map or aerial photograph, consists of the sharp rectangular edges of an extant medieval fish pond. This feature is one of a number Repton railed against in his text and, whilst invisible to the naked eye, is clearly a feature that the park has unknowingly retained.
The new image pinpointed the location of a pre-Repton avenue leading from Barton hall to the River Ise. Intriguingly, the locations of other individual trees were identified in other long-lost avenue locations. This drilling-down cartographic accuracy from vague 19th century map symbols to 21st century georeferenced plots enabled a very specific authenticity to be brought to the replanting plans.
Elsewhere in the park, the smooth rolling contours of the existing parkland were rolled back to reveal an intricate web of ridge and furrow ploughing, in many cases overlaying earlier cultivation terraces of as yet unknown date. Combined with historic research, this allowed long-lost trackways to be found and named and individual strips to be linked to specific tenants dating back centuries.
The LIDAR mapping provided us with a tsunami of previously unknown site information which
we continue to use in developing the site master plan. The information provides a guide to avoid damage but also direct creative strategies in both planting and site interpretation.
However these are not tools that can be used by all. Competence in terrain analysis at this level is patchy at best in the professions of landscape architecture and archaeology, as it is often left untaught in many of our universities. One cannot assume when provided with LIDAR information in this form that all professionals are competent to use it in a positive manner. The maps will only ever be as good as the interpreter that uses them.
In addition we know that the resolution of such maps can fall short of identifying key elements of archaeological heritage. In this case a complex of 16 Iron Age roundhouses is barely visible and a complex of Roman cellars does not register at all.
The future of unpicking the stratigraphy of sites across the country is extremely exciting. The low-resolution data sets provided by the Environment Agency will soon be overtaken by high-resolution, site-specific LIDAR surveys undertaken by the now ubiquitous drones. This will mean that sooner or later it may well become incumbent on site master planners to reconnoitre their sites by LIDAR as a matter of course, prior to making any big decisions. Indeed as this technology is dispersed further and deeper across society it would be a very naïve master planner who risked development proposals when faced with an opposition potentially packing their own Lidar interpretation, information that could introduce critical new site information when well into a development proposal.
As professionals with a hand in the process of directing development it would be foolish, verging on the negligent, to not take advantage of all of the fantastic new tools that are becoming available to us in the process of investigating and making sound decisions regarding the future of our precious landscape.
John Pegg is a founder of Craft Pegg landscape architects.