Interview: Professor Iain Stewart

How Earth Made Us

How It Works: Tell us about your latest series for the BBC, How Earth Made Us.
Iain Stewart: It is a sideways look at history through the lens of geology, taking our modern understanding that the planet is in a constant state of flux and that its forces can effect dramatic change over human timescales and exploring what that has meant for us in the past. For some this is Big History, but for me it is about emphasising the human face of geological change. What I hope it offers is to encourage people to think more broadly about just what the planet means to us and what our responsibilities are.

HIW: Do you think it will help viewers appreciate where we’ve come from as a result of the planet’s awesome power?
IS: Well, more than anything, I hope it reminds them of what an amazing planet we live on. The inter-connected nature of our planet’s machinery – links between its interior, oceans, ice sheets, and atmosphere – are constantly surprising us, which makes the Earth fantastically exhilarating to study. But, at the same time, the fact that many of those surprises have big implications for our future gives earth science a growing sense of real purpose.

HIW: You have been described as a geologist, a television presenter, and ‘Earth Man’ among others. Which title best describes you?
IS: I’m an earth scientist. That’s the day job. The television presenting is great fun but it’s just the chance to communicate on an enormous scale the same stuff that I do in the lecture rooms at Plymouth.

HIW: What was the most thrilling new fact that you discovered on this latest adventure?
IS: I like how geology offers an alternative angle on the contemporary world, like the fact that it is estimated it would take the Earth 3 million years to make enough oil for just one year of our consumption. Now that is living beyond our means.

HIW: What, so far, is the most remarkable place you’ve seen on Earth?
IS: It has to be the Crystal Cave in Mexico – any geologist would give up their right arm to enter that wonderland. But other highlights were the methane-burping mud volcanoes of Azerbaijan, the singing sand dunes of the Libyan Sahara, and wallowing in brine pools in an Iranian salt cave. Oh, and playing five-a-side football (and pulling a hamstring) in a oil-drilling town built on stilts in the middle of the Caspian Sea. This really was a whirlwind tour through the planet’s weird and wonderful.

HIW: When you entered the Cave of Crystals in Mexico it looked otherworldly. As a lover of the environment and natural history, how did it make you feel to experience these extraordinary sights?
IS: It’s oppressively hot and humid, you’re weighted down with kit, and you dread losing your footing on the slippery sheen of the crystals, but none of that really mattered. It was the raw beauty of the place that took your breath away. You had to remember that you were in there to work, otherwise you’d just be entranced. The miners believe there are similar but bigger caverns deeper down, but because it’s a working silver mine it would be too much effort and disruption to open them up. As it is, they plan to block and reflood this one, so the planet will get it back.
Maybe it’s for the best – perhaps the Crystal Cave is best seen as a symbol of the innumerable remarkable worlds that lie hidden beneath our feet, just waiting for the time when humans seriously look to explore downwards rather than up to the heavens.

HIW: Is there one special gadget that you wouldn’t leave for an expedition without?
IS: My standard geological compass-clinometer is invariably tucked away in the rucksack, but it is the MacBook and iPhone alongside it that ends up being essential for keeping up with the day job.

HIW: What is next on your to-do list?
IS: I’m off to Scotland for a BBC4 series that looks at how the roots of some of the most fundamental ideas about how the planet worked emerged from of a tiny but rich piece of geological real estate to the north of Carlisle. Geology is coming home!

How Earth Made Us is available on DVD from the BBC Shop, priced £9.99.