Geochemical baseline survey of the environment (G-BASE)

Select an option from the list below to view high resolution images and data about soils across Great Britain.

The Geochemical Baseline Survey of the Environment (G-BASE) is a major British Geological Survey (BGS) campaign of geochemical sampling across many parts of the UK. The core function is to provide a national capability in baseline geochemical analysis of water samples, stream sediment and soils.

See G-BASE regional geochemical mapping for further information on the areas that have been sampled between 1985 and 2013 and how to acquire this data.

Beginning in the late 1960s, the primary focus was mineral exploration, however the project has now evolved into a multi-media, high-resolution geochemical survey producing baseline data relevant to many environmental issues. G-BASE is a project within the Geochemical Baselines and Medical Geology Team area. Its main activities can be classified as either Regional or geochemical baseline mapping. Recent work has focused on the geochemical mapping of London.

The regional G-BASE project has collected samples at a density of one sample per 2km2; from mostly agricultural fields. High density soil geochemical data are also available for 25 major cities and towns of Great Britain. Soil samples were collected as part of the G-BASE project at a density of four sites per 1km2 within the build-up areas. Each sampling site a surface (5-20cm) and a profile (35-50cm) sample were collected (and a third topsoil sample from 0-2cm across Greater London). Inorganic analytical data are available for over 50 determinands.

High density soil geochemical data are also available for 25 major cities and towns of Great Britain. Soil samples were collected as part of the G-BASE project at a density of four sites per 1km2 within the build-up areas. At each sampling site a surface (5-20cm) and a profile (35-50cm) sample were collected (and a third topsoil sample from 0-2cm across Greater London).

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 © [year]".

Profile soil analyses are available from a number of BGS programmes, notably the Mineral Reconnaissance Programme (MRP) and the G-BASE programme. Sampling depth and range of analytes determined is very variable for the MRP. G-BASE samples are consistently from 35-50cm though since 2003 it has become routine practice in the G-BASE project to collect a top soil and deeper profile sample from the same site but only analyses the top soil and store the profile soil. This also applies in urban areas. The G-BASE profile soils were generally sieved to 150 microns before analysis and determined by XRFS for some or all of: Mg, P, K, Ca, Ti, Mn, Fe, V, Cr, Co, Ba, Ni, Cu, Zn, Ga, As, Se, Rb, Sr, Y, Zr, Nb, Mo, Pb, Bi, Th, U, Ag, Cd, Sn, Sb, Cs, La, Ce, Ge, Sc, Se, Br, Hf, Ta, W, Tl, Te and I.

MRP samples can include profile samples from greater than 1m collected using a power auger and also include till samples. The G-BASE samples are collected at a density of 1 sample per two square kilometres in rural areas and 4 samples every km2 in urban areas. MRP sampling was more site specific generally collecting soil samples along lines at spacing intervals generally 25-250m.

G-BASE profile soil (points) map
Title G-BASE profile soil (points)
Source British Geological Survey
Enquiries enquiries@bgs.ac.uk
Scale(s) Point data
Coverage Great Britain
Format GIS point data
Price A free WMS service is available (see below)
Uses Local to national level use
Map Viewer View in UKSO Map Viewer
WMS link https://map.bgs.ac.uk/...
Images High resolution | low resolution

These topsoil samples were collected mainly by the G-BASE programme. Regional (generally rural) samples are collected at an average density of one site per 2km2, urban sampling is at a density of 4 samples per km2. Topsoil samples are collected at a depth of 5-20cm, sieved through a 2mm mesh and milled to less than 150 microns prior to analysis. The data include analyses for some or all of the following elements by XRFS: Mg, P, K, Ca, Ti, Mn, Fe, V, Cr, Co, Ba, Ni, Cu, Zn, Ga, As, Se, Rb, Sr, Y, Zr, Nb, Mo, Pb, Bi, Th, U, Ag, Cd, Sn, Sb, Cs, La, Ce, Ge, Sc, Se, Br, Hf, Ta, W, Tl, Te and I. Loss on Ignition (LOI) and pH (in a slurry of 0.01 M CaCl2 ) is now routinely determined on 50% of regional and all urban samples.

MRP samples can include profile samples from greater than 1m collected using a power auger and also include till samples. The G-BASE samples are collected at a density of 1 sample per two square kilometres in rural areas and 4 samples every km2 in urban areas. MRP sampling was more site specific generally collecting soil samples along lines at spacing intervals generally 25-250m.

G-BASE topsoil (points) map
Title G-BASE topsoil (points)
Source British Geological Survey
Enquiries enquiries@bgs.ac.uk
Scale(s) Point data
Coverage Great Britain
Format GIS point data
Price A free WMS service is available (see below)
Uses Local to national level use
Map Viewer View in UKSO Map Viewer
WMS link https://map.bgs.ac.uk/...
Images High resolution | low resolution