The idea of the Anthropocene as a geological ***epoch*** is a conceit showing mankind's self delusions of grandeur. Geological time is deep beyond all comprehension. If you were to run a 26.2-mile marathon spanning the entire retrospective sweep of Earth’s history in reverse, the first five-foot stride would land you two Ice Ages ago and more than 150,000 years before the whole history of human civilization. In other words, geologically and to a first approximation, all of recorded human history is irrelevant: a subliminally fast 5,000-year span that is over almost as soon as you first lift up your heel.
The only potential usefulness of the "Anthropocene" concept is as a tool to raise urgent awareness (already too late) of the perils of climate change.
But to the concepts behind the proposal, here is what traditional geological thinking has to say about it:
-- Whereas some epochs in Earth history stretch more than 40 million years, we are told this new epoch started as recently as 75 years ago, when atomic weapons began to dust the planet with an evanescence of strange radioisotopes. This is a laughably tiny amount of time that would barely even qualify to be designated an "event" in geologic terminology.
-- Geology typically deals with mile-thick packages of rock stacked up over tens of millions of years, wherein entire mountain ranges are born and weather away to nothing within a single unit of time, in which extremely precise rock dates — single-frame snapshots from deep time — can come with 50,000-year error bars, a span almost 10 times as long as all of recorded human history. If having an epoch shorter than an error bar seems strange, well, so is the Anthropocene proposal.
-- Plutonium is proposed here as the start of the Anthropocene's mark on the geologic record. Ignore plutonium for a moment, because even the longest-lived radioisotope from radioactive fallout, iodine-129, has a half-life of less than 16 million years. That is tiny in geologic time scales. If there were a nuclear holocaust in the Triassic, among warring prosauropods, we wouldn’t know about it today because no trace would remain.
-- The presence of plastic fibres and fragments is also offered as a possible marker of our impact. How about that instead? Indeed small samples from our tiny geologic stratum that interrupts mile-thick formations of otherwise normal rock might be detectable. However, a few thousand years — or even a few tens of thousands of years — will be virtually indistinguishable in the rocks a hundred million years hence. The clear-cutting of the rain forest to build roads and palm-oil plantations, the plowing of the seabed on a continental scale, the rapid changes to the ocean and atmosphere’s chemistry, and all the rest would appear ***simultaneous*** with the extinction of the woolly mammoth. To future geologists, the modern debate about whether the Anthropocene started 10 minutes ago or 10,000 years ago will be a bit like arguing with your spouse on your 50th wedding anniversary about which nanosecond you got married.
The following article is recommended reading to get a true grasp on the staggering time scale of deep geologic time and the arrogant folly of the idea of an Anthropocene epoch:
www theatlantic com /science/archive/2019/08/arrogance-anthropocene/595795/