The geology of the future

Image by Bakhrom Tursunov from Pixabay
Dear Editors,
The articles arguing in favour of the Anthropocene as a formal epoch (Geoscientist, Autumn 2024) made interesting and well-argued reasoning. Now that geology has been gifted a second globally distributed, unequivocal time marker (the first being the iridium layer that defines the Chicxulub impact event some 66 million years ago and the second the occurrence of human-made atomic particles from nuclear bomb tests), regardless of whether it precisely marks a brief event or the start of something longer lasting, that marker should absolutely be the basis of a ‘golden spike’ reference section for the geological timescale.
Some argue against defining the Anthropocene as a formal epoch, claiming that it will be geologically insignificant and/or that humans significantly impacted Earth’s systems long before 1950. However, there is evidence to suggest some life was in trouble well before the fatal single event that marks the Cretaceous–Paleocene mass extinction. Likewise, the Anthropocene can still be ‘golden spiked’ even if human influence predates the chosen date.
Geologists, unlike historians and geographers, rarely have the luxury of dating that is accurate to within a decade, and generally rely on approximate ages using relative dating methods. While we geologists are well versed at looking into Earth’s deep past many are generally less inclined to extend this view far into the future. Imagining a time far ahead, how long can future geologists continue to call their version of the present, Holocene? Looking back from that future, given current extinction rates, it may be clear that Earth has entered a new phase – potentially a new period or era, let alone an epoch or stage.
Depositional environments will continue to lay down strata containing modern materials far into the new geological record. Plastics, for example, which are also unique to human folly, and now found literally everywhere (even in human tissue), will define more than just a passing event (geological time could even be counted in terms of BP, Before Plastic, and PP, Post Plastic). Regardless of whether the time of humankind is minutely short in terms of geological time, the by-products of humanity will be recorded in rocks, and easily detectable, and this time needs a name. ‘Plasticocene’ feels rather apposite.
More generally, I find it alarming that critical scientific decisions can be made by committee vote rather than solid scientific reasoning. Presumably the subcommission voting process that ruled out the Anthropocene Epoch was similar to that responsible for replacing the Tertiary Period with the Paleogene and Neogene. Arguably, with a first and second period never really adopted, a third and a fourth was seen as anomalous, so both the Tertiary and Quaternary were removed initially. Continuing to reject the Tertiary (3rd) while reinstating the Quaternary (4th) seems utterly illogical (e.g. Head et al., 2008). At only just over 2 million years the Quaternary is also unusually short as typically periods, including the Tertiary, span around 50 million years, so its reinstatement in 2009 (Gibbard et al., 2009) seems disproportionate and influenced by geomorphologists and geographers.
Changing the original naming system (which is still widely used) was a confusing and pointless mistake; so I say keep the Quaternary, bring back the Tertiary, and add the Anthropocene, acknowledging common sense and the persistence of human-made materials.
Richard F J Arthur BSc FGS
Director at Earth Images, UK
Further reading
- Gibbard, P.L., Head, M.J, Walker, J.C. and the Subcommission on Quaternary Stratigraphy (2009) Formal ratification of the Quaternary System/Period and the Pleistocene Series/Epoch with a base at 2.58 Ma: Journal of Quaternary Science 25, 96–102; https://doi.org/10.1002/jqs.1338
- Head, M.J., Gibbard, P. & Salvador, A. (2008) The Tertiary: a proposal for its formal definition. Episodes 31, 248-250; https://doi.org/10.18814/epiiugs/2008/v31i2/012