From Jeffrey Harte, Caringbah, New South Wales, Australia
While the International Union of Geological Sciences (IUGS) has declared that we are still in the Holocene epoch (28 July, p 24), I believe the “Anthropocene” is functionally and stratigraphically different to the Holocene. But when did it start and what evidence is appropriate to distinguish the two?
The idea of a layer of plastic rubbish as a marker is unlikely to be appropriate, because over many millennia rock strata are reworked vertically and laterally. Perhaps, though, the result will be a band of “plastiglomerate” lithic material that could serve as a new worldwide marker. Maybe the growth of radionuclides in sediments accumulated since the 20th century will provide a uniform marker. The priority of the IUGS may be nomenclature – defining eras, periods, epochs and ages. But it needs to acknowledge the impact of a species on the geological record and not, as Mark Maslin and Simon Lewis intimate, go out of its way to confuse members of the public.
