Humanity and the Geological Record

Some while ago I was half watching yet another documentary about the meteorite impact which caused significant problems for the dinosaurs some 65 million years ago. One of the big scientific clues is the layer of iridium in the rocks, known as the K-T Boundary – which suggested that something had caused a planetary wide settlement of rock in a very short period of time (in geological terms).

So far – so normal.

Then I got thinking about mankind’s impact on the geological record.

In a very short timeframe, mankind has variously mined and dug up vast quantity of minerals and then spread them around the surface of the globe – in the form of manufactured goods. Also, we have paved over land and built whole cities from stone based materials (concrete etc) and minerals (steel, iron etc).

Let us presume that something terrestrial was to wipe out a large percentage of the animals on the planet – such as a pandemic virus or similar.

Give the planet a few million years, and there will be no obvious surface memory of the existence of humans at all – we will have ceased to exist. However, there will be a geological record – in the form of a thin layer of concentrated minerals and pulverized rocks which is spread almost over the entire planet.

At some time in the future, it is not inconceivable that a new species of animal would evolve and have cognitive abilities. Their scientists may look into the past by studying rocks – as humans do now and they will come to conclusions about the past thanks to the geological record.

What would they think about our period of history?

They might notice that there are fossils of a small creature which seemingly walked on two legs and had two arms with a head at the top of the body. Not actually that sensible a design, as the head is only loosely connected to the body and not well protected – but this small creature seemed to find the ability to exist in most parts of the planet, although regional variations are noticed.

Then suddenly, it seems as the whole species had just vanished – along with huge swathes of other species which inhabit the planet at the time. At around the same time this happened, the geological record shows a near planet wide thin covering in minerals and crushed rocks. They might also note from ice cores that there was a sharp spike in CO2 within the planets atmosphere at about the same time.

What are these future scientists to conclude from this?

An obvious conclusion to reach is that the planet was once inhabited by upright walking mammals who seemed to be predominantly vegetarian and probably lived in small herds. However, there was a titanic meteorite impact which covered the planet in a thick layer of minerals and shattered rocks – and the following “nuclear winter” would have killed plants and these rather odd little mammals could not have survived.

Our future scientist might ponder that had earth not been hit by a meteorite – would they have evolved into intelligent creatures?