Landscapes beyond the shoreline

During the last few decades, there has been considerable offshore exploration for oil and gas. A more general programme of marine research has also been initiated and facilitated by new research vessels (the Celtic Explorer and the Celtic Challenger). Many exciting discoveries have been made about the undersea topography surrounding Ireland.

Celtic Explorer
Courtesy of webmaster@galway.net.

A series of large sedimentary basins have been mapped, among them the Porcupine Basin to the west, the North Celtic Sea basins off the south coast, and the small Kish Bank basin near Dublin Bay. Intriguingly - and in contrast to the situation on land - these basins contain thick sequences of relatively young rocks from the Mesozoic Era.

Carbonate mound map

This map illutrates where exactly the carbonate mounds are beyond the shore line. Map drawn by Stephen Hannon, based on work by Prof Pat Shannon, B.M. O'Reilly, P.W. Readman, P.F. Croker, O.O'Loughlin and others.

Courtesy of Arnold Horner 2006.

Carbonate mound map
Courtesy of Arnold Horner 2006.

Carbonate mound map

Courtesy of Arnold Horner 2006.

Enlarge image

The discovery of 'carbonate mounds', has been among the most dramatic of recent offshore discoveries. Analogous to the coral reefs of the tropics, these mounds have been found along he margins of the Porcupine Bank and Rockall Trough some 200-400 km off the west coast. Occurring in water depths of 800-1000 metres, they can be up to 250 metres high.

They are a reminder that the Irish landscape exists within a wider setting and that the 'landscape', broadly conceived, does not stop at the present shoreline. Perhaps, indeed, the large elevated, and heavily eroded, but nonetheless basin-like, feature that is Ireland has more structural links to these offshore features than we initially realise.

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