New mapping method leads to seabed discovery

 

UNIVERSITY College Cork (UCC) scientists have produced the first detailed charts of part of Ireland’s offshore bedrock geology, using a new method of mapping.

The work was undertaken by Russian-born marine geologist Dr Max Kozachenko of UCC’s Coastal and Marine Research Centre and UCC geology lecturer Dr Pat Meere.

They explain that although extensive swathes of Ireland’s offshore territory have been mapped by the national seabed survey, the details of bedrock formation can be hard to determine due to the environment’s inaccessibility.

Geological mapping relies on a combination of photographic interpretation, processing of specialised data and field studies – the latter being difficult or prohibitive at any depth of water.

The team took a section of the southwest coast to conduct extensive coastal fieldwork, and to evaluate existing terrestrial bedrock geology maps and aerial photographs.

They interpreted bathymetric data from multibeam surveys, data from aircraft surveys, and other data sets from the underwater offshore area collected as part of the national seabed survey.

The areas chosen by the UCC scientists focused east of the Old Head of Kinsale and west in Bantry and Dunmanus bays, Co Cork.

They noted “extensive areas of outcropping rocks” with “clearly expressed bedding and fracture patterns on high resolution multibeam mapping”.

“This work revealed the full complexity of performing geological mapping in the offshore environment, where direct measurements are near to impossible,” they say.

A thorough knowledge of geology nearby onshore is required to come to correct conclusions about seabed topography, they add.

They say that their “workable methodology” can be extended to other areas using the rich source of data collected as part of the seabed survey – run jointly by the Geological Survey of Ireland and the Marine Institute and known as Infomar.

Infomar (Integrated Mapping for the Sustainable Development of Ireland’s Marine Resources) is a successor to the initial Irish national seabed survey, which focused on offshore territory extending to 10 times the island’s land size.

It had mapped 81 per cent of that territory by late 2005.

The current work is focusing on inshore areas and involves 26 bays, one biologically sensitive area and three “priority” areas off the south and east coasts.