OR/15/020 Model datasets

Thorpe, S. 2015. Metadata report for the Knowsley 3D geological model . British Geological Survey Internal Report, OR/15/020.

DTM

The DTM source was NEXTMap (Intermap Technologies Inc) at a 25m cell size resolution. The date of the DTM extraction was not recorded but it is assumed to be the date that modelling commenced — Sep 2007

Borehole data

Borehole information was taken from the current BGS corporate databases — Single Onshore Borehole Index. Additionally, over 300 paper borehole records were provided by the Agency from previous environmental site investigations carried out in the industrial park and incorporated into the BGS databases. In total, 1279 coded boreholes were used in the study. Of these, 733 were used to construct 58 geological cross-sections (Price et al., 2008^[1]). One site investigation containing 11 boreholes has subsequently been found to contain boreholes whose start height was based on a local survey. These boreholes sit approximately 26m above the model DTM, and in these cases the boreholes were hung from the DTM in order to use their data in drawing the sections.

Map data

The 1:50 000 DigMapGB-50 digital geological data (natural superficial deposits and bedrock) which was used to guide the cross-section drawing and creation of the geological unit distributions was extracted from version 4.16 in 2008 and was derived from the 1930s survey of the Wigan sheet which did not include artificially modified ground. Although modelling then took place approximately concurrently with resurvey of the district (1999–2010) any consequent revisions from the latter were not fed into the shapefiles that were utilised within the model. In addition, the Made Ground envelope drawn for the model differs in detail from the survey. Thus there are discrepancies from the final map data published in the Wigan 1:50 000 sheet in 2013 (and to be included in DiGMapGB-50 v8) which are only partly due to generalisation. Incorporating the updated natural superficial deposits and bedrock data into the model and the Made Ground into DiGMapGB-50 would require further intervention that for the moment cannot be justified [A J Mark Barron and S Thorpe, 09/03/2015]

GVS data

See Appendix

Geological Legend (GLEG) data