Witham Valley National Mapping Programme
Aerial survey reveals the complexity of past landscapes
An initial study of this complex landscape was prompted by the discovery and excavation of a prehistoric causeway at Fiskerton. The archaeological potential of the Witham Valley in Lincolnshire was highlighted in 'Time and Tide: The Archaeology of the Witham Valley' (Catney and Start, 2003). This report proposed a programme of research to investigate landscape change and settlement in the Valley from prehistoric to medieval times.
The NMP survey used vertical and oblique aerial photographs as the main source of information. However, the project was also used as an early test of lidar for archaeological survey. The earliest forms of monument identified from aerial photography were prehistoric barrows. Their distribution shows distinct clusters at focal points in the landscape. This pattern suggests their siting was a deliberate and culturally significant act. Near Barlings Abbey, at the confluence of Barlings Eau and Stainfield Beck, there is a large Bronze Age barrow cemetery. As can be seen in the image below, some barrows survive as low earthwork mounds in the pasture field to the left, while others have been levelled and are visible only as pale marks against the darker peaty soil.
Medieval monastic sites
The siting of monastic sites within the Witham Valley and the relationship of medieval abbeys with earlier features is apparent. The coincidence of existing road causeways, some of which may have had their origins in prehistory, is of particular interest.
The NMP mapping has revealed areas of levelled archaeology visible as soilmarks and cropmarks and places the monastic sites in their landscape context. South Kyme Augustinian Priory is located on the north bank of the River Slea and is one of several monastic sites within the wider Witham Valley. The complexity of the monastic plan is superimposed by a medieval moated manor and post medieval gardens.
Roman land management
Little new evidence of Roman settlement was found in the low lying areas of the Witham Valley. More information has been recorded on the Car Dyke, which is a prominent feature in the flat fen landscape.
The Car Dyke was originally thought to be a Roman canal, but is now believed to be part of a 1st or 2nd century AD fen drainage system. It follows a sinuous course down the south and west side of the Witham Valley. The dyke survives as earthworks for long stretches but levelled sections can be seen as cropmarks. The central ditch has substantial banks flanking it, which possibly acted as flood defences.
Duck decoy ponds
The fens have a long history of exploitation. During medieval and post medieval times duck decoy ponds, constructed to catch wildfowl, were common. Duck decoy ponds were first introduced in Lincolnshire and Essex before spreading to other counties.
Witham Valley lidar
During the project, the opportunity was taken to use lidar data flown by the Environment Agency in 2001. The data was only 2 metre resolution rather than the higher 1 metre resolution acquired for the Stonehenge survey, but it was still considered a useful exercise to compare data sources. There were a number of technical issues that prevented the data being viewed in the most efficient way, but the project still produced some useful data.
One of the first findings was that the lidar data produced very clear images of the geomorphology. It was particularly good for highlighting palaeochannels and earlier river courses. Instead of mapping these natural features, the processed lidar was used as background images.
The lidar data showed a number of known features such as barrows and enclosures but also identified previously unrecorded sites. One of the most interesting of these was near Stixwould. Here evidence was found for a causeway that may once have led to the priory. The image below is colour coded from blue (low) to red (high) according to elevation.The site of the priory is visible as a raised(red) area in the centre of the image with a low bank leading towards it from the bottom of the image. The bank is defined by the line of a modern track before heading diagonally across fields where the modern field boundaries overlie the causeway.
A cautionary tale
The project also showed the importance of using all available sources, not just relying on one or two. The site below was seen on lidar and thought to be a Roman fort. However, the historic photographs clearly showed that it was actually the remains of the Second World War airfield at Bardney.
Further details of the lidar survey can be found in Archaeological Prospection Volume 13, Issue 4, 251-257.
The images used on this page are copyright Historic England unless specified otherwise. For further details of any photographs or other images and for copies of these, or the plans and reports related to the project please contact the Historic England Archive.
For further information on a project or any other aspect of the work of the Remote Sensing Team please contact us via email using the link below.
Historic Places Investigation
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The aerial survey of much of Lincolnshire and parts of North Lincolnshire was part of an NMP mapping project completed between 1992 and 1997.