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    This low-resolution image has been produced from BGS land and marine gravity data. The colour was generated using the BGS COLMAP software package. Colour levels are defined by histogram equalisation. Combining this image with the grey shaded relief image produces a similar image to the colour shaded relief image. The measured gravity values have been corrected in order to show the anomalies attributable to variations in crustal density. In broad terms the blues are attributable to large volumes of low density rocks, the reds to high density rocks. Significant lows occur, for instance, over areas of thick, low density sedimentary rocks(e.g. Cheshire Basin, Wessex Basin), or large granites (eg Cornwall). For marine data, free-air anomalies have been calculated from observed gravity values along marine survey lines. Line intersection errors between crossing lines and overlapping surveys have been used using network adjustment techniques. Free air anomalies have been calculated for sea-bottom stations. For land data, bouguer anomalies have been calculated from gravity observations at points of known height. In order to minimise the effect of topography, Bouguer corrections for the British Mainland have been applied using a density estimated for each station. Elsewhere a correction density of 2.67 Mg/m3 has been used. Corrections for the gravitational effect of terrain have been made where significant, and in a general extent to a radius of 48.6km. The data have been interpolated onto a 1km x 1km grid using a variable tension technique, and smoothed.

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    Oju/Obi is a remote part of Eastern Nigeria. There are severe water shortages during the 4-5 month dry season. The hydrogeology of the area is complex, and groundwater is difficult to find. In an attempt to understand and quantify the available groundwater resources within the area, DFID commissioned BGS from 1997 – 2000 to carry out a hydrogeological review of the area and devise appropriate and effective methods for siting wells and boreholes assessing groundwater resources and how best these resources could be developed. The field study involved the collection of time series data including groundwater chemistry and rainfall Cl along with mineralogical information. These results are being used by WaterAid, Local and regional Government to help local communities develop sustainable water supplies.

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    This layer of the map based index (GeoIndex) providex an index to 17,500 borehole rock samples (drillcore) from the Mineral Reconnaissance Programme (MRP) and related studies. The UK Government's Department of Trade and Industry (DTI) funded BGS to provide baseline information on areas prospective for the occurrence of metallic minerals in Great Britain. This programme, known as the MRP, ran continuously from 1973 to 1997 and covered particular locations across Great Britain. It was designed to stimulate private sector exploration and to encourage the development of Britain's indigenous mineral resources. Under the programme a number of boreholes were drilled to gather information.

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    The map shows the localities where samples that form part of the BGS rock collections have been taken. Many of these samples are from surface exposure, and were collected by BGS geologists during the course of geological mapping programmes. Others are from onshore boreholes or from mine and quarry workings. The principal collections are the E (England and Wales), S (Scotland), N (continuation of the S collection) and the MR (miscellaneous). The collections, which are held at the BGS offices at Keyworth (Nottingham) and Edinburgh, comprise both hand specimens and thin sections, although in individual samples either may not be immediately available. Users may also note that the BGS holds major collections of borehole cores and hand specimens as well as over a million palaeontological samples. The Britrocks database provides an index to these collections. With over 120,000 records, it now holds data for some 70% of the entire collections, including the UK samples shown in this application as well as rocks from overseas locations and reference minerals. The collections are continuously being added to and sample records from archived registers are also being copied into the electronic database. Map coverage is thin in some areas where copying from original paper registers has not been completed. Further information on Britrocks samples in these and other areas can be obtained from the Chief Curator at the BGS Keyworth (Nottingham) office or from the rock curator at the BGS Murchison House (Edinburgh) office.

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    The data shows the location of seabed and sub-seabed samples collected from the UK continental shelf, held by BGS. A BGS Sample Station is a general location at which sampling with one or more equipment types, such as borehole, grab, dredge, has been used. Historically, all deployment of equipment was recorded with the same coordinates so the data shown here will often show several sets of data at the same location. Newer data will begin to show distinct locations based on an equipment type. This layer shows all the BGS Sample Station Locations, including those where the Sampling was unsuccessful. The layers below are divided into distinct equipment types, plus a separate layer for unsuccessful sampling. BGS Sample Station Locations can have a wide range of potential information available. This can vary from a basic description derived from a simple piece of paper up to a complex set of information with a number of datasets. These datasets can include particle size analysis, geotechnical parameters, detailed marine geology, geochemical analysis and others. Prices are available on further enquiry.

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    This layer of the map based index (GeoIndex) shows the availability of 1:63360 scale geological maps. The maps are available for most of England and Wales and show early geological mapping covering the OS Old Series one inch map sheet areas.

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    This layer of the map based index (GeoIndex) shows the location of earthquakes within the UK. The historical catalogue has been compiled, in general, from macroseismic observations (ie felt effects). Before 1700, only earthquakes with magnitudes of 4.0 ML or greater are included. After 1700, all known events with magnitudes of 3.0 ML or greater are included together with some other, smaller ones. Accuracies of magnitude, location, and origin time vary with the quality of information available for this period as they do for instrumental measurements in the post 1970 period. In that case, variations are largely a function of the seismograph station coverage, which has been improving up to the present day.

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    An index to over 600 ground geophysical surveys carried out in the UK for a variety of projects. A large number of these surveys were done in conjunction with the DTI Mineral Reconnaissance Programme in the 1970's and 80's, and many others were carried out at the request of BGS field mapping groups. Information held describes the survey objective, location of measurements, geophysical methods and equipment used, reports and publications, storage locations of data and results (for analogue and digital data), dates and personnel. There are two datasets; one shows the outline of the survey areas, and the other shows the actual survey lines within each area.

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    This layer of the map based index (GeoIndex) shows the location of available Mineral Assessment Reports, the information for the index has been taken from the BGS UK Sand and Gravel Database. Each report studied the sand and gravel resources of an area of between one hundred and two hundred square kilometres. This layer shows individual polygons of the geographical areas covered by each report. Selecting the individual polygons via the map based index (GeoIndex) application gives details of the corresponding report title, number, author(s), subtitle and the date report was first published. The Department of the Environment commissioned this Report series from the British Geological Survey.

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    This layer of the GeoIndex shows the localities for which details of identified fossil specimens in the BGS Biostratigraphy Museum are databased. Only Ordovician and Silurian specimens listed currently. Samples and taxonomic identifications will be listed and will in future be able to be queried using the query-by-attribute tool to the right of the map. See also Fossil Localities. Material is available for inspection on application by e-mail; it is free for academic research but is charged for commercial work. Specimens are sometimes available for loan to bona fide academics.