OR/14/057 Model assumptions and limitations

Arkley, S L B, Finlayson, A G, and Callaghan, E A. 2014. Model metadata report for the Forres GSI3D superficial deposits model. British Geological Survey Internal Report, OR/14/057.

• Best endeavours (quality checking procedures) were employed to minimise data entry errors but given the diversity and volume of data used, it is anticipated that occasional erroneous entries will still be present (e.g. borehole location).
• The model does not reflect the full complexity of the superficial deposits geology. In reality, surfaces have been subjected to more glacitectonic deformation than is represented in the model.
• The NEXTMap^® Digital Elevation Model may contain artefacts such as trees or artificial structures such as pylons. If any of these artefacts were found during the modelling then the effects of these were minimised in the model as much as possible.
• The start heights of boreholes used might differ significantly from the NEXTMap^® Digital Elevation Model. When modelling, these differences were taken account of by assessing the year the borehole was drilled and assessing the location of the borehole against other data such as historical maps. Therefore the modeller used their own judgment in some areas if the stratigraphy in the borehole did not match the modern day topography and changes in the subsurface (quarrying, landfill etc).
• The thin nature of some superficial deposits means that these units are poorly shown in visualisations of the 3D model (e.g. in the Lithoframe Viewer 3D window). A substantial number of additional cross-sections (‘helper sections’) are needed to improve the calculation of thin deposits.
• The heights of raised marine deposits resulting from past sea-level changes were assumed.
• There was a lack of borehole information in the west part of the model, thus this part of the model is heavily reliant on mapping.