2. The Tellus airborne geophysical surveys and results

The Tellus airborne geophysical survey of Northern Ireland was flown in 2005–6 and the Tellus Border survey of the six most northern counties of the Republic of Ireland in 2011–2. Together the two surveys covered a region of approximately 25,000 km2, or 30% of the land surface of the island of Ireland. Three parameters were measured and mapped: magnetic field, electrical conductivity and gamma rad…