“…Extrusive fluid flow features such as mud, chalk and sand volcanoes in theory likewise record the timing to the paleo-surface onto which they occur. The extrusive nature can however be hard to establish on seismic data and the timing of formation should thus be supported by observations such as reflection terminations like onlaps and downlaps (Mitchum et al, 1977;Stewart and Davies, 2006;Hansen et al, 2005;Andresen et al, 2009Andresen et al, , 2010. Sandstone intrusions may also represent useful timing indicators if they are associated with forcedfolding of the overburden and onlaps (Shoulders and Cartwright, 2004;Frey-Martínez et al, 2007;Cartwright, 2010;Andresen, 2011).…”