The Earth After Us

A review of ‘The Earth after us: what legacy will humans leave in the rocks?’ by Jan Zalasiewicz. Oxford, Oxford University Press. 2008.
The view of the Earth from the Moon on the front of the book seems both familiar and strange at the same time. The blue jewel of a planet is recognisably ‘home’, only a few decades since space travel first made such a perspective possible. But look again and an important difference is noticed. The continents are the wrong shape, and in the wrong configuration. Is this a view of our planet in the distant past? No, this is the Earth as it is imagined to be 100 million years into the future.
Geologist Jan Zalasiewicz invites the reader to take a step in the scientific imagination far greater than that involved in looking at the Earth from the Moon. For the challenge taken up by the book is to look back at human civilization from a vantage point in time long after the human species itself has disappeared, through observations made by alien beings visiting the planet for the first time. Seeking to understand the geological strata encountered, the alien scientists soon realise that something significant happened 100 million years ago, comparable to the meteorite strike that wiped out the dinosaurs even further back in the Earth’s past. Even before they discover it, they deduce the existence of an event horizon, separating two major geological epochs – an event that triggered massive climate change and extinctions of species evident in strata from later periods. Following a trail of clues, they discover the Human Event Stratum.
The Human Event Stratum may vary from a thin sliver to several metres in thickness, sandwiched between layers of sandstone and shale. Parts of it will have been destroyed by erosion or other geological processes. It is mostly buried, hundreds of metres under the ground, but in places it has been pushed up or exposed by geological forces to outbreak on the surface. Ever wondered what will survive, millions of years hence, of our railway networks, skyscrapers, motorways and rubbish dumps? What about trains and cars, or smaller artefacts like mobile phones and ballpoint pens? Such are the questions which the book poses. In this review I consider briefly some of the implications this book has for contemporary archaeology.

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