Combining numerical and cognitive 3D modelling approaches in order to determine the structure of the Chalk in the London Basin

8 9 In order to determine the structure of the Chalk in the London Basin, a combined cognitive and 10 numerical approach to model construction was developed. A major difficultly in elucidating the 11 structure of the Chalk in the London Basin is that the Chalk is largely unexposed. The project had to 12 rely on subsurface data such as boreholes and site investigation reports. Although a high density of 13 data was available problems with the distribution of data and its quality meant that, an approach 14 based on a numerical interpolation between data points could not be used in this case. Therefore a 15 methodology was developed that enabled the modeller to pick out areas of possible faulting and to 16 achieve a geologically reasonable solution even in areas where the data was sparse or uncertain. 17 18 By using this combined approach, the resultant 3D model for the London Basin was more 19 consistent with current geological observations and understanding. In essence, the methodology 20 proposed here decreased the disparity between the digital geological model and current geological 21 knowledge. Furthermore, the analysis and interpretation of this model resulted in an improved 22 understanding of how the London Basin evolved during the Cretaceous period. 23 24 2