Boulder ridges on the Aran Islands: New perspectives.

Last month I went to Inish Mor to look at potential sites for my Ph.D research on rock coasts and to meet with Professor Ronadh Cox from Williams College in Massachusetts.  

Prof. Cox was accompanied by  three of her undergraduate students; Josh, Jordan and Zeek, who were helping to collect data for an ongoing project which started in 2008. The project was initiated after one of Prof. Cox’s students became intrigued by the origin of accumulations of boulders high above sea level on the cliffs of Inish Mor. Eight years later Prof. Cox and her students are continuing to investigate these deposits. Up until quite recently, most would have argued that only a tsunami could transport boulders from sea level, over the cliff top and sometimes up to 20m inland. Prof Cox and her students have been monitoring the movement of these boulders by painstakingly recording any changes in their position and orientation. The data collected has demonstrated that powerful storm waves could well be responsible for these boulder deposits.

Boulder ridges on Inish Mor off the west coast of Ireland.  Credit: Ronadh Cox

Boulder ridges on Inish Mor.
Credit: Ronadh Cox

This year, Prof Cox is utilizing improvements in technology to introduce a new method of monitoring the movement of these boulders, Structure from Motion (SfM) Photogrammetry. Although photogrammetry in itself is not a new technique, the introduction to mass market of unmanned aerial vehicles (UAVs), or drones, in combination with the availability of user friendly software, has resulted SfM Photogrammetry becoming an increasingly popular tool in geomorphological research. These advances allow researchers like Prof. Cox to examine features like the Aran Island’s boulder ridges from a new perspective with relative ease.

During the expedition, a consumer grade drone was flown along pre programmed path taking oblique and plan view images. The images were then processed by specialized software to produce high resolution 3D models of the surveyed terrain. By comparing the 3D model with models created from future surveys, Prof. Cox will be able to monitor movement of the boulders in detail and provide further insights into the dynamics of these intriguing deposits.

By Niamh Cullen

PhD Candidate with the Earth and Planetary Surface Processes GroupDepartment of Geography, Trinity College Dublin. 

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