A methodology for obtaining descriptive statistics for soils overlying different parent material in the Humber-Trent atlas region

This report describes a methodology for generating descriptive statistics for soils above different parent materials in the British Geological Survey’s (BGS) Humber-Trent Atlas region. There is a need to compile this type of statistics both for (i) public enquiries and (ii) populating domains on the new Parent Material Map under development at BGS. Instructions are given to link G-BASE soil data downloaded from the corporate Geochemistry Database, linking it spatially to v0.1 of the Parent Material Map within ArcMAP v9.1 and downloading the combined data into an Access database. A macro is run within Access to generate the required descriptive statistics that include maximum and minimum values, the range of data, arithmetic mean and standard deviations and geometric mean and standard deviation. For demonstration purposes, descriptive statistics are presented for the parent material classification used in the BGS Rock Classification Scheme (RCS). Further statistics were generated for parent materials split into the different geological ages of the RCS. This will produce more appropriate statistics for the Parent Material Map. After completion of this report an updated version of the macro used to generate the descriptive statistics was created. This was too late to be used in the majority of work. However, in Appendix 4, a small additional example has been added using the improved macro that includes the facility to generate percentile values.