Superficial Deposits Thickness Model (SDTM)

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Dataset Description:

The BGS’s Superficial Deposits Thickness Model (SDTM) dataset shows the depth of the bedrock surface, beneath the top layer of superficial deposits (the youngest of geological formations and generally including sediments deposited during glacial episodes, rivers and coastal systems, and man-made deposits).  Knowing the thickness of the superficial deposits layer, and therefore the depth of the bedrock, is critical to a range of tasks such as civil engineering, groundwater assessment, and prediction of surface hazards such as landslides and subsidence.


The SDTM dataset is a 1:50,000 scale, 50m cell size raster (grid) dataset which has been created by interpolation of approximately 600,000 borehole logs from SOBI, combined with the extent of the superficial deposits theme within the BGS Geology 50k dataset (DiGMapGB-50).  Three individual layers are provided within the SDTM product:


  • ASTM (Advanced Superficial Thickness Model) – a model of thickness variation indirectly derived from archive borehole records and map data
  • BSTM (Basic Superficial Thickness Model) – a model of thickness variation directly derived from archive borehole records
  • DBUFF (Distance Buffer) – a calculation of spatial distance to the location of any data point used in the model (interpolation distance)


Dataset Thumbnail:


Dataset Specification:

Product Name: Superficial Deposits Thickness Model (SDTM)
Data Provider: British Geological Survey (BGS)
Scale: 1:50,000
Coverage: Great Britain (complete)
Data Structure: Raster grid
Uses: Bedrock depth
Licencing: BGS Licence
Update Frequency:


Dataset Resources:

Product site
User Guide (pdf)