In early February I stumbled across news that Google Earth was going to be made freely available, waiving the $400 it had previously cost to subscribe. Before then I had never really paid it much attention, so read up a bit on what you can do with Google Earth. The thing which stuck out was that you can use it to examine the viewshed of a particular point.
When reading about a castle, you typically find that it view is described as ‘impressive’ or words to that effect. Software such as GIS allows you to quantify that statement. GIS software often comes with a hefty licence fee, and while there are free alternatives Google Earth was incredibly simple to use.
The method for creating a viewshed in Google Earth is explained here. As soon as I tracked down this information, I started using it to look at castle sites. The first place I turned to was Pennington on the Furness Peninsula. As I worked at Buckton Castle I become more interested in the ringwork castles of the North West. Pennington struck me as the most interesting, particularly because its history is opaque, it hasn’t been excavated, and the site is has regularly been included on English Heritage’s annual ‘At Risk’ registers.
I have tried to get in touch with the owners of the property with little success, so the viewshed tool offered a small way to learn a bit more about the castle. The area is based on land visible from a point 10m above ground level, assuming there was a tower of some sort. As can be seen below, areas north and west of the castle were hardly visible, while there was a much clearer view to the south and east. This helps understand why the entrance is on the south side of the ringwork, aside from the route of Pennington Beck, a small stream which flows through the area. The south and east is evidently where most of the traffic would have been coming from.
This is a simplistic approach, but complimented by manorial records to and local history could lead to a more in-depth understanding of the area and why the castle was built.