Since we started the augering of the site in 2018, as reported in a previous blog post, we have completed some 8 lines across the site in an E-W direction, each containing boreholes spaced at 2m apart. The length of each line varies according to the site boundary but containing usually about 15 boreholes. The various strata have been examined as they are logged with a view to determining the ancient ground surface, which could be river gravels or an orange clay. Above these levels are generally river sediments (over the gravel) or layers containing silt due to subsequent flooding and/or organic remains such as twigs or small riverine snails.
In order to visualise this ancient land surface underneath the modern, generally flat, appearance of the gardens, we have constructed a digital elevation model (DEM) of the surface within the geographic information system QGIS which we use to plot the Millhams project. An interim result is shown in this blog, which comprises a snapshot from a 3D model of the DEM with shading and colour contouring. Although not complete, the impression we have gained of an ancient channel running through the site can be clearly seen.