This marine multi-channel geophysical survey commissioned by the British Geological Survey (BGS), acquired and processed by Seismograph Service (England) Ltd took place 22nd August to 24 May and 13th Julyto 29th July 1968 in the Irish Sea aboard m.v. Norbjorn. Navigation: Decca Main chain. Sub surface data were gathered using explosive charges, 1094km were covered by 11 lines. These data are archived by BGS. Technical details of the survey are contained in an Acquisition Report.