OR/18/003 Model datasets

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Shelley, C, and Burke, H. 2018. Model metadata report for the South Downs teaching model. British Geological Survey Open Report, OR/18/003.

This section lists the datasets used to inform the South Downs teaching model.

GVS and GLEG files

The generalised vertical section (.gvs) and geological legend (.gleg) files were assembled and iterated as the model expanded and new units were encountered. The GVS and GLEG were created using BGS DiGMapGB-250 data.

Geological linework

The model uses BGS DiGMapGB-250 bedrock mapping. Some of these units are grouped together in the model, such as the Thames Group (THAM), which is composed of London Clay Formation and Bagshot Formation.

Digital terrain model

The model is capped by the Ordnance Survey Terrain 50 Digital Terrain Model (DTM), which is subsampled to a cell size of 100 m. Offshore the ground elevation is taken as sea level. The model uses borehole data extracted from BGS corporate databases. A review of borehole records in the BGS Single Onshore Borehole Index (SOBI) in the model area was carried out and those that held sufficient geological information were selected for coding in the BGS Borehole Geology database (BoGe). Boreholes were coded with bedrock units from the BGS Lexicon http://www.bgs.ac.uk/lexicon/

The Rock Classification Scheme (RCS) http://www.bgs.ac.uk/bgsrcs/ was used as appropriate to record lithologies and named geological units.

A total of 482 boreholes were used in the South Downs teaching model. These were used to inform 30 cross-sections, including six from the UK3D model (Figure 2).

Figure 2 Distribution of borehole logs used to inform the 30 cross-sections in the South Downs teaching model. UK3D sections are shown in blue. ©Crown copyright and database rights (2018) Ordnance Survey (100021290 EUL).

Additional data

The South Downs teaching model uses data from pre-existing geological models. Base surfaces for the Palaeogene, Chalk Group, Gault Formation and Wealden Group were imported from the Weald Basin geological model (Hulbert and Terrington, 2014[1]) were used to inform the South Downs teaching model.

A base Chalk surface from the Itchen model was also used to inform the South Downs model, as well as surfaces from the Chichester model (Terrington et al, 2016[2]).

The South Downs teaching model is matched to cross-sections from the BGS UK3D geological model of the United Kingdom (Waters et al, 2015[3]).

References

  1. Hulbert, A G, and Terrington, R L. 2014. Metadata report for the Weald Basin 1:250 000 resolution geological model. Unpublished. British Geological Survey Open Report OR/14/026. http://nora.nerc.ac.uk/id/eprint/507268/
  2. Terrington, R L, Gow, H, and Aldiss, D T. 2014. Model metadata report for the 3D model of the superficial deposits near Chichester. British Geological Survey Open Report OR/14/71.
  3. Waters, C N, Terrington, R L, Cooper, M R, Raine, R J, and Thorpe, S. 2016. The construction of a bedrock geology model for the UK: UK3D_v2015. Unpublished. British Geological Survey open report OR/15/069.http://nora.nerc.ac.uk/id/eprint/512904/