This Web service provides layers which are part of the BGS Superficial Deposits Thickness Model (SDTM) series of datasets. It currently includes two layers from the STDM 1 km hex grid dataset, which is available under the Open Government Licence. These two layers are symbolised on the mean and maximum values of the BSTM thickness model within the area of each hexagon. In these two layers, note that the data include a generic value of 1 m thickness for any area where superficial material is present, but is unproven by boreholes (shown on the map by a grey colour).