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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.
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.
The BGS Seabed Sediments 250k dataset is vector data is vector data which reflects the distribution of seabed substrate types of the UK and some of its adjacent waters at 1:250,000 scale. This comprehensive product provides a digital compilation of the paper maps published by BGS at the same scale, as well as, additional re-interpretations from regional geological studies. The seabed is commonly covered by sediments that form a veneer or thicker superficial layer of unconsolidated material above the bedrock. These sediments are classified based on their grain size reflecting the environment in which were deposited. This information is important to a range of stakeholders, including marine habitat mappers, marine spatial planners, offshore industries (in particular, the dredging and aggregate industries). This dataset was primarily based on seabed grab samples of the top 0.1 m, combined with cores, dredge samples and sidescan sonar acquired during mapping surveys since the early 1970s. The variations in data density will be reflected in the detail of the mapping.
Faeroe-Iceland Ridge Experiment (FIRE) was acquired by BIRPS (the British Institutions Reflection Profiling Syndicate). The primary target was anomalously thick oceanic crust along the Faeroe-Iceland Ridge that was possibly formed by underplating due to the proximity of the Iceland hotspot. FIRE made use of 110 land seismometers to record the airgun shots. The resulting velocity models and reflector geometries have proved critical in interpretation of variations in crustal volumes along the ridge. The data were recorded to 23 s two-way time.
This layer of the map based index (GeoIndex) shows sites where regularly monitored rest water level data are available, usually covering a long time period. The data shows seasonal fluctuations in the water table and responses to periods of high or low rainfall.
In 1992, BIRPS joined with the Indonesian Marine Geological Institute to record two long multichannel normal-incidence reflection profiles, one of which is DAMAR, the other TIMOR, and one short profile (API) close to the volcano Gunung Api. The survey provides a modern analogue to tectonics hypothesized to have occurred across the Iapetus suture zone of northern England 450-400 Ma. The Banda Arc of Indonesia near the island of Timor is widely recognized as the premier example of the active subduction of continental crust and lithosphere beneath oceanic lithosphere. The crossing of a modern island arc and close passage to active volcanoes was intended to image reflections associated with magma in the crust and uppermost mantle.
Data identifying landscape areas (shown as polygons) attributed with geological names. The scale of the data is 1:250 000 scale providing a generalised geology. Onshore coverage is provided for all of England, Wales, Scotland and the Isle of Man. Data are supplied as two themes: bedrock and linear features (faults), there is no superficial, mass movement or artificial theme available onshore at this scale. Bedrock geology describes the main mass of solid rocks forming the earth's crust. Bedrock is present everywhere, whether exposed at surface in outcrops or concealed beneath superficial deposits or water bodies. Geological names are based on the lithostratigraphic or lithodemic hierarchy. This means rock bodies are arranged into units based on rock-type and geological time of formation. Where rock-types do not fit into the lithostratigraphic scheme, for example intrusive, deformed rocks subjected to heat and pressure resulting in new or changed rock types; then their classification is based on their rock-type or lithological composition. This assesses visible features such as texture, structure, mineralogy. Data identifying linear features (shown as polylines) represent geological faults at the ground or bedrock surface (beneath superficial deposits). Geological faults occur where a body of bedrock has been fractured and displaced by large scale processes affecting the earth's crust (tectonic forces). The faults theme defines geological faults (shown as polylines) at the ground or bedrock surface (beneath superficial deposits). The data are available in vector format (containing the geometry of each feature linked to a database record describing their attributes) as ESRI shapefiles and are available under BGS data licence.
The British Institutions Reflection Profiling Syndicate (BIRPS) shot approximately 12,000 km of deep, multi-channel seismic reflection data around the British Isles from 1981 to 1991 during 14 surveys. Recording depths vary depending on the purpose of the survey but range from 15 s to 40 s two-way time. Raw and processed digital data are archived by BGS who make the data available subject to the cost of reproduction and handling. Seismic sections and other analogue ancillary data are available for some surveys. Gravity and magnetic data may also be available.
Data identifying landscape areas (shown as polygons) attributed with geological names and rock type descriptions. The scale of the data is 1:25 000 scale. Onshore coverage is partial and BGS has no intention to create a national coverage at this scale. Areas covered are essentially special areas of 'classic' geology and include Llandovery (central Wales), Coniston (Lake District) and Cuillan Hills (Isle of Skye). Superficial deposits are the youngest geological deposits formed during the most recent period of geological time, the Quaternary, which extends back about 2.58 million years from the present. They lie on top of older deposits or rocks referred to as bedrock. Superficial deposits were laid down by various natural processes such as action by ice, water, wind and weathering. As such, the deposits are denoted by their BGS lexicon name, which classifies them on the basis of mode of origin (lithogenesis) with names such as, 'glacial deposits', 'river terrace deposits' or 'blown sand'; or on the basis of their composition such as 'peat'. Most of these superficial deposits are unconsolidated sediments such as gravel, sand, silt and clay. The digital data includes attribution to identify each deposit type (in varying levels of detail) as described in the BGS Rock Classification Scheme (volume 4). The data are available in vector format (containing the geometry of each feature linked to a database record describing their attributes) as ESRI shapefiles and are available under BGS data licence.
This dataset comprises data from Wessex Archaeology surveys which were conducted over various wreck sites between 2003 and 2010. Three of these datasets were acquired in English waters, one in Welsh waters and one in Scottish waters. The geology and geophysics component of the data are archived by British Geological Survey (BGS) in the Marine Environmental data and Information Network (MEDIN) Data Archive Centre (DAC) for Geology and Geophysics. The data include multibeam echosounder, single-beam echosounder, sidescan sonar, sub-bottom profiler, magnetometer, and geological data (vibrocore logs and photos). Data were also provided to other archive centres as appropriate - UKHO (bathymetry), Royal Commission Ancient and Historic Monuments Wales (geophysics), Royal Commission on the Ancient and Historical Monuments of Scotland (geophysics and diving/ROV), Archaeology Data Service (diving/ROV). Although generated for archaeological purposes, these high quality and resolution data are capable of re-use by marine surveyors and scientists from a range of different fields. Data are delivered via the BGS Offshore GeoIndex www.bgs.ac.uk/GeoIndex/offshore.htm and additional data are available on request firstname.lastname@example.org.