This report describes the rationale behind the construction of the Nottingham Melton Lithoframe 50K GOCAD model for the Colston Bassett area. This work was carried out between April 2001-March 2005, as part of the Nottingham Melton DGSM-UK project (E1362S96 Task 06). This model comprises part of the area covered by the Melton 50K geological map sheet (142)