BRITISH AND Finnish geologists began a major airborne geophysical survey of Northern Ireland last month.
The survey is part of the Tellus project, sponsored by the Northern Ireland Department of Enterprise, Trade and Investment and managed by the Geological Survey of Northern Ireland. It is being carried out by the British Geological Survey (BGS) and the Geological Survey of Finland (GTK).
Tellus, named after the Roman goddess of the Earth, is a countrywide geophysical and geochemical mapping project aimed at providing key information to underpin protection of the environment, sustainable land use and sustainable development of natural resources.
The airborne study will use a de Havilland Twin Otter owned by the Natural Environment Research Council, the BGS's parent body. It is equipped with a dual-frequency electromagnetic system designed and built by GTK, a multi-channel gamma spectrometer and a magnetic gradiometer.
Data will be collected at a ground clearance of between 56m and 240m, along parallel fl ght lines spaced 200m apart. About 90,000km will be surveyed during the eight-month project, during spring and summer this year and next.
Electromagnetic data will provide information on the electrical conductivity of the subsurface, which varies in relation to rock type, water saturation, water quality, pollution and mineralisation.
Magnetic data will give details of the subsurface structure and mineral resources, while radiometric data charts radioactivity in near-surface rocks and soils.