A GIS-based application of drainage basin analysis and geomorphometry in the submarine environment: the Gollum Canyon System, Northeast Atlantic

The Gollum Canyon System (GCS) – more commonly referred to as the Gollum Channel System (Kenyon et al., 1978; Beyer et al., 2003, 2007; Wheeler et al., 2003; Van Rooij, 2004) – lies approximately 100 km off the southwest coast of Ireland, within the Porcupine Seabight (Figure 3.1). First identified by Berthois and Brenot (1966), the east-west orientated dendritic canyon system incises significantly into the seafloor for a distance of over 200 km. It lies in water depths of between 200 m to 3500 m, and is surrounded on four sides by continental shelf, with a restricted opening out onto the Porcupine Abyssal Plain in the southwest (Akmetzhanov et al., 2003). Downslope sedimentary processes within the canyon system were most active during glacial low-stand periods via turbidites and other mass wasting events, while interglacial periods have exhibited little or no sediment transfer activity (Van Rooij, 2004). Direct observations show contemporary sedimentary activity within the system to be minimal, with tidal currents and northward.