Above, a lidar plot from EA data of the Lincolnshire Marsh at Marshchapel showing extensive remains of medieval salt production. Below, the same plot overlain with William Haiwarde's 1595 map of the parish demonstrating the remarkable accuracy of this early mapping (although it has taken a little work in QGIS to make it fit quite this well). Almost as remarkable as his very accurate depiction of the shape of the salterns is the fact that they retain that recognisable shape to this day. At the time of his survey Haiwarde depicted small structures (salt cotes) on the most easterly of the salterns, but these were clearly the last active salterns for no more have been developed beyond these after 1595.
