As well as masking the underlying substrate, emplacement of this volcanic material will have undoubtedly altered the thermal and chemical structure of the lithosphere. Clear evidence of age-progressive volcanism both on-shore and off-shore point to a plume source (Sutherland et al., 2012 and Davies et al., 2015), but there are apparent exceptions, including the Quaternary Newer Volcanics Province in Victoria (Demidjuk et al., 2007).