Latest Tellus findings reveal ‘hidden depths’ of Ireland’s north midlands

The recent phase of the Geological Survey’s Tellus Programme has discovered volcanoes more than three hundred million years old under the Midlands.

The 330-million year old rock formations were discovered on the Westmeath/Offaly border south of Mullingar by a low-flying aircraft using the latest mapping technology. Flying at 90m, technology used on the survey aircraft sensed geological features not apparent from conventional mapping techniques, effectively ‘seeing through’ Ireland’s often deep glacial deposits and extensive peat cover.

The results also show sections of volcanic rocks under the ground near Strokestown, County Roscommon. The rocks are part of a major fault line that can be traced through Ireland and to Scotland. These structures are known to be important in the development of mineral deposits and their location will be of considerable interest to exploration companies.

Ray Scanlon, principal geologist at the Geological Survey of Ireland, anticipates that the freely available data will be put to a wide range of practical uses: “Tellus continues to reveal extraordinary new detail in Ireland’s geological landscape buried beneath our feet, building upon existing data gaps and developing natural resource opportunities.

“An understanding of Ireland’s geology is vital for environmental, health and economic reasons, and the data will be welcomed by a broad range of stakeholders for agricultural, radon prevention, groundwater protection, and mineral exploration purposes.”

The fourth phase of Tellus is currently underway across eastern Ireland where the airborne survey over Offaly, Kildare, Meath, rural Dublin, and northern parts of Wicklow and Laois is almost 60 per cent complete. Attention is currently focused on rural County Dublin. While weather dependent, good progress has been made to date and the Tellus team aims to survey 50 per cent of the country by the end of 2017 on a phased basis.

The maps also reveal new detail of 330 million-year-old volcanoes on the Westmeath/Offaly border south of Mullingar which appear in the new airborne geophysical data as a cluster of small magnetic bodies. The findings from the north midlands are significant as they contribute another piece to the jigsaw of Ireland’s first seamless cross-border geoenvironmental mapping project which began in 2007.

Airborne geophysical data for the border and north midlands regions are now available, free of charge to view and download, at


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