This vector contour dataset represents the distribution of the theoretical potential calculated 'identified resources' (in GJ/m2 or PJ/km2) for the Carboniferous Fell Sandstone Formation (Mid Border Group) in the Northumberland-Solway Basin. The theoretical potential for 'identified resources' represents the estimated proportion of the geothermal resource that is available for development. For consistency with other legacy estimations, additional columns have been added to the original layers to include the converted value of 'identified resource' to 'recoverable heat' in MW/km2, for equivalence to the method used by D J.R. Jones, T. Randles, T. Kearsey, T.C. Pharaoh, A. Newell (2023). https://doi.org/10.1016/j.geothermics.2023.102649 and Kearsey, T.I., Receveur, M. and Monaghan, A.A., 2024. Modelled hot sedimentary aquifer geothermal potential of Upper Devonian strata in the Midland Valley of Scotland.