Framework-forming cold-water corals (CWC's) such as Lophelia pertusa and Madrepora oculata generate positive topographic features on the seabed called CWC mounds. In the North East Atlantic, CWC mounds have been studied in detail and reveal heterogeneous spatial on-mound organisation of coral patches. Many of these studies are limited by a paucity of remotely-sensed and video imagery at an appropriate resolution and coverage. This study is the first attempt to video mosaic an entire CWC mound (the Piddington Mound of the Moira Mounds, Porcupine Seabight, Irish margin). The mosaic is divided into 18,980 0.25 m2 cells with a manual classification applied to each within a geographic information system (GIS). Geospatial analysis shows that cell distribution is not random but clustered significantly across the mound surface. These clusters of cells make up a ring-like facies pattern. A model for the processes that lead to this facies pattern is suggested based on contemporary environmental controls. Parallels to shallow-water reef atolls are also drawn which subsequently has implications for interpreting fossil coral outcrops. Highlights► We present the first attempt at video mosaicking an entire CWC mound. ► Detailed facies distribution analyses are utilised to demonstrate facies organisation across the Piddington Mound surface. ► Main facies on the Piddington Mound are Live coral framework, Dead coral framework and Coral rubble. ► Coral rubble dominates the summit while live coral framework facies dominate the upper mound flanks. ► We interpret potential influences on this distribution and draw some parallels with shallow water reef atolls.

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