Epoch, Age, Zone or Nonsense

The International Commission on Stratigraphy lists 37 Series/Epochs and 85 Stages/Ages in the latest version of the International Stratigraphic Chart for the 11 Systems/Periods of the Phanerozoic. A great battle against ICS’s attempt to extinguish the Quaternary, the only enduring Era originated by Giovanni Arduino (1714-1795) and Johann Gotlob Lehmann (1719-1767), now seems to have ended in a compromise (Kerr, R.A. 2008. A time war over the period we live in. Science, v. 319, p. 402-403). While that vigorous struggle has apparently petered out, the Stratigraphic Commission of the Geological Society of London has launched another by proposing a new Epoch – the Anthropocene. This follow a suggestion by Nobel laureate and chemist Paul Crutzen that the Holocene Epoch ended once humanity made a significant impact on the Earth system (Zalasiewicz, J. and 20 others 2008. Are we now living in the Anthropocene? GSA Today, v.18(ii), p. 4-8).

The device intended by the ICS to mark boundaries between Periods, Epochs and Ages in the Phanerozoic is a symbolic Global Standard Section and Point (GSSP), combining an absolute age definition and a type section. A growing number of boundaries are marked by a physical ‘golden’ spike (not necessarily made of gold) including a plaque engraved with the Period or Age names, welded into the agreed boundary itself. There is good reason for this seemingly odd behaviour; geologists need to have agreed nomenclature and locations so that their discourse can be internationally sensible. It is also a deeply exciting, even exalting moment when any geologist puts her/his finger on a boundary of global significance: and how supremely triumphant actually to wield the hammer that drives the spike home. So much so, that there have been monumental squabbles, some not far short of diplomatic ‘incidents’, about exactly where GSSPs should be placed.

But the whole bureaucratic process has its awkwardly humorous side. There is a proposal that the GSSP for the Pleistocene/Holocene boundary be located in a Greenland ice core. Is that to be in the hole left by the NGRIP core drill at the centre of Greenland, at the depth at which evidence for the warming at the end of the Younger Dryas (11.5 ka) occurs? Or should it be in the core itself – a GSSP in a fridge? Either way, it is going to be difficult to put a finger on that particular boundary Moreover, global warming and the attendant social disruption might remove both. The proposed Anthropocene might have an even stranger GSSP. For a start, when did it begin? An anthropogenic human signature appears clearly in the NGRIP core around 8 ka bp, and at a variety of levels in pollen records, but the GSL’s Stratigraphic Commission wants it to start at the beginning of the Industrial Revolution. Sadly, that is a profoundly diachronous, economic boundary. To make it Eurocentric, as Crutzen suggested, would be a bit non-PC.

Let’s face it, the Holocene is just an interglacial, similar to a great many since 2.4 Ma ago. It is noted only for the brief period in which humanity became separated into two groups: a very small one owning the means of production; the other, initially diverse, being forced to work for the first in order to survive. The Industrial Revolution marked a social simplification into two opposed classes, as clearly defined by Marx, and the increased dominance of human affairs by an inhuman entity called capital. The working through of the contradictions bound up in class society and in capital itself has been largely responsible for the huge environmental changes drawn on by Zalasiewicz et al. It seems our somewhat po-faced authors forget the great many more scholars of human affairs than there are geologists: historians and political economists. Already there are plenty of anthropocentric equivalents of GSSPs in London itself, in the form of its celebrated blue plaques. Historians and political economists might well agree that the rise to dominance of capital – and hence the emergence of rapid environmental change during the uniquely short-lived Anthropocene – began outside the Banqueting Hall on Whitehall at 2.04 pm on Tuesday 30 January 1649 with the separation of the head of the divinely righteous monarch, Charles I, from his body. Ladies and Gentlemen of the SC of the GSL, that is where you place your ‘golden’ spike. However, geology might yet have its say, any time now (and geologists cannot really foretell): a super-volcanic eruption; a comet strike or a cosmic gamma-ray burst. So you had better be quick, if your aim is posterity.

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