The Gollum Canyon System (GCS) is the largest submarine canyon system in European waters extending 250 km from the shelf break to the Porcupine Abyssal Plain. Commonly referred to as the Gollum Channel, the morphometric analysis presented here suggest that it is infact a submarine canyon and therefore best referred to as the Gollum Canyon System. An analysis of regional multibeam echosounder data for the entire Porcupine Seabight was conducted with drainage network analysis revealing the true dendritic canyon system present. The GCS is far more expansive than previously thought, proving that GIS-based flow accumulation models as seabed mapping analytical tools reveal significantly more information not possible by visual inspection of sun-illuminated DTMs.
The drainage network analysis has provided modelled proof of hydrological links between the previously separate Elven, Kings and Gollum Canyon Systems. Evidence is also provided of sediment transfer shutdown in canyons due to canyon capture overtime. Additional morphometric analysis has revealed that channel morphologies and orientations are controlled in part by the shallow sub-surface geology within the basin. Tectonic inversion and compressional reactivation of former rift margin faults in the Neogene generating stages of tectonic uplift appear to have occurred concurrently with the development of the GCS, with channels showing evidence for morphological responses to steepening slopes. Evidence of a northward shutdown of the system, with canyons becoming infilled, is also seen, likely tracking changes in sediment supply routes across the shelf in response to the development of Northern European ice sheets.
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