London and the Thames Valley

Geological model of London and the Thames Valley.

The National Geological Model (NGM) is an accurate, multi-scaled, geospatial model of the subsurface arrangement of the rocks and sediments of the UK.

The NGM currently includes the Great Britain bedrock fence diagram (UK3D) and a number of other 3D geological models.

One of these models is in the London and the Thames Valley area and covers 4800 km2, extending westwards as far as Newbury and eastwards to the inner Thames Estuary. It was developed by BGS from 2007 onwards and was released in 2014.

The London and the Thames Valley model delineates the geological boundaries between 80 artificial, superficial and bedrock units in the Thames Valley and extends from the surface to a maximum depth of several hundred metres.

Construction

The Quaternary and Palaeogene bedrock geology was modelled using a cross section-based approach. This involved the construction of a geological framework comprising 922 hand-drawn cross sections that considered over 7174 borehole records.

Coverages of the plan-view distribution of each geological unit were drawn utilising where possible, DiGMapGB-50 map linework. Both the cross sections and the coverages were interpolated between to create the solid geological model for the upper units.

The lower geological units from the Chalk to the Jurassic (undivided) strata were modelled via interpolation between borehole data and are of a lower resolution than the shallow model.

For more information see The London Basin superficial and bedrock LithoFrame 50 Model report.

Boreholes considered in the London geological model.
Hand-drawn cross sections across the London geological model area.

Application

The geological model is well-suited to the following applications:

  • borehole and section prognoses
  • as a framework for the construction of higher resolution, more detailed geological models for site-specific and local studies
  • catchment and regional-scale assessments for hydrogeology, planning, mineral resource estimation
  • general and geoscience education

Limitations

The following limitations should be considered, a complete list of limitations is available on the Groundhog webpage:

  • the model should not be used outside of its intended resolution
  • the model may need refinement for site-specific use or mineral reserve quantification
  • the surface linework on the model may differ from that on DiGMapGB-50
  • thin veneer units such as head and clay with flints and the artificial and made ground deposits are represented in 2D and will not appear in section or borehole prognoses
  • not all available boreholes were considered in the construction of the model
  • local features such as scour hollows, pingos and small channel infills may not be modelled

Availability

Sections of the geological model of London and the Thames Valley that are available to download.

The geological model is available in a variety of formats through BGS Groundhog:

  • borehole and section prognoses
  • individual surfaces in TIN (triangular irregular networks), ascii grids, ESRI or GOCAD shells, 3D grids
  • interactive 3D viewer (Lithoframe Viewer)

The pdf file is a 3D pdf; it will allow you to rotate the model in 3D by dragging the mouse in the pdf window and you can turn on and off the topography map and cross sections in the model tree.

If the model is not displaying properly, enable double-sided rendering using the following instructions:

Right click in the 3D window — 3D Preferences — 3D and Multimedia — make sure enable double-sided rendering is checked on.

Download a preview of the London and Thames Valley geological model