John Pitchford's Witham

John Pitchford's 1733 map of the course of the River Witham from Lincoln to Boston, produced at a scale of 2 and a half inches to the mile (1:25,344), unfortunately does not survive. This version 'correctly reduced and drawn from the original' in 1734 is at nearer 1:80000. Nonetheless, a very accurate piece of survey for its day. It shows the route of the river prior to improvements in the 1870s. Neither of the Projected Cuts laid out here were ever undertaken, the final scheme taking a route inbetween the two. The map is overlain onto a lidar map produced from Environment Agency data showing the detailed topography of the valley and the Witham fens and the course of the prehistoric estuarine river.

Maryport lidar

Lidar from the usual source (EA). Slope severity plot looking NE, showing the setting of the Roman fort at Maryport very well.

Here, looking in much the same direction, a sky-view-factor plot showing the impressive detail of the surviving earthworks. Excavations have been ongoing for a year or two. Plenty there to go at.

Caerwent

The smaller scale image doesn't really do this justice. This is extracted from Environment Agency 0.25m centred lidar survey data. Not much UK coverage at this scale, mostly very tightly focused on coastal zones and river valleys, but they do happen to have covered the site of Venta Silurum. The detail of the wall circuit and bastions, and of exposed Roman building foundations within the town, is quite amazing (for what is, essentially, an off-the-shelf product).

Here, the same expressed as a sky-view factor plot and viewed as a 3D model from the south-west.