G-BASE for south west England

Area covered by this survey

A systematic, high density geochemical survey of the south west of England has been completed as a part of the UK-wide G-BASE project. The region's geochemical baseline has been characterised through the collection and analysis of soils and stream sediments.

These spatial data are relevant to both human and ecological health, land use planning and development, contaminated land legislation and regulation, soil fertility, agricultural development and mineral exploration, and supporting informed decision making.

Applications of baseline geochemical datasets include:

  • providing a marker of the current state of the environment for the measurement and monitoring of future change
  • identifying anomalous values resulting from, for example, mineralisation and industrial contamination
  • assessing the condition and health of soils and sediments for agricultural and ecosystem functions
  • identifying and quantifying human impact on the environment, indicating elevated concentrations of potentially harmful elements
  • identifying new opportunities for mineral exploration
  • support and information for local councils, developers and the general public on environmental or health hazards

Sample and data collection

The average sample density for stream sediments is approximately one site per 2.5 km2. Density for soils in south west England is variable across the area, ranging from one per 2 km2 to one per 5 km2, depending on the nature and variability of underlying geological parent material.

Analytical quality is high with strict quality control to ensure countrywide consistency. Results have been standardised to ensure continuity with existing G-BASE geochemical data.

Analytical (X-ray fluorescence) data for the sub-150 μm fraction of stream sediment and the sub-2 mm fraction of soil samples are available for some or all of:

Ag, Al, As, Ba, Bi, Br, Ca, Cd, Ce, Cl, Co, Cr, Cs, Cu, Fe, Ga, Ge, Hf, I, In, K, La, Mg, Mn, Mo, Na, Nb, Nd, Ni, P, Pb, Rb, S, Sb, Sc, Se, Si, Sm, Sn, Sr, Ta, Te, Th, Ti, Tl, U, V, W, Y, Yb, Zn, Zr.

Soil and sediment geochemical maps are available below (Table 1) to download as pdfs, or to view using the Tellus south west interactive map viewer.

The downloads are interpolated maps of soil and stream sediment geochemical data based on the analysis of 1154 shallow (0.05 – 0.20 m) soil samples, collected at varying densities (ranging from one per 2 km2 to one per 5 km2, depending on underlying parent material homogeneity), and 3720 stream sediment samples collected at an average density of one per 2.5 km2.

The images for soils and stream sediments were generated using an inverse distance weighting (IDW) algorithm applied to the nearest 12 samples within a variable search radius capped at 10 km, and a cell size of 500 m × 500 m.

The interpolated images show element concentrations between known sample points.

The colour ramp is based upon percentile classes of the data distribution.

Soil and sediment geochemical maps and data available for download

Terms of use:

These data are delivered under the terms of the Open Government Licence, subject to the following acknowledgement accompanying the reproduced BGS materials: "Contains British Geological Survey materials © NERC [year]". Contact us if you create something new and innovative that could benefit others usingbgsdata@bgs.ac.uk

Extent of G-BASE for SW England
Stream sediment sample site locations
Soil sample site locations

High (resolution): pdf download

Low (resolution): jpg lightbox

Element Soil Sediment
Antimony (Sb) high low More information high low More information
Arsenic (As) high low More information high low More information
Barium (Ba) high low More information high low More information
Cadmium (Cd) high low More information high low More information
Calcium (Ca) high low More information high low More information
Cerium (Ce) high low More information high low More information
Chromium (Cr) high low More information high low More information
Copper (Cu) high low More information high low More information
Hafnium (Hf) high low More information high low More information
Iron (Fe) high low More information high low More information
Lead (Pb) high low More information high low More information
Manganese (Mn) high low More information high low More information
Molybdenum (Mo) high low More information high low More information
Nickel (Ni) high low More information high low More information
Potassium (K) high low More information high low More information
Samarium (Sm) high low More information high low More information
Selenium (Se) high low More information high low More information
Silicon (Si) high low More information high low More information
Silver (Ag) high low More information high low More information
Strontium (Sr) high low More information high low More information
Thorium (Th) high low More information high low More information
Tin (Sn) high low More information high low More information
Titanium (Ti) high low More information high low More information
Tungsten (W) high low More information high low More information
Uranium (U) high low More information high low More information
Zinc (Zn) high low More information high low More information
Zirconium (Zr) high low More information high low More information

How to license data

Visit BGS onshore geoindex to search for individual sample locations within the UK. Make sure the map theme is set to geochemistry (top right hand corner) and top or profile soil or stream sediment is selected in the left hand panel.

To license data for south west England, or for any other G-BASE related queries, please get in touch with BGS enquiries.

Details on the various campaigns, field operations, sampling procedures or sample site distributions can be obtained from G-BASE downloads.

Contact

Data from this project are available under license by contacting the BGS enquiries team.

BGS offers expertise in all aspects of baseline geochemistry, including sampling and data visualisation and interpretation, and the applications of surface geochemistry data to human and ecological health studies. In particular BGS has expertise to provide underpinning geochemical interpretation of the relationships between the long history of metal mining in south west England and a legacy of elevated concentrations of metals in river sediments and floodplain soils, especially with respect to current UK and European legislation. Additional information on the expertise is available. Alternatively contact Bob Lister or Joanna Wragg for additional information.