Journey to the centre of the Earth

Our ability to think about the processes that shape our planet is underpinned by a basic question: How old is that rock? Geologists have long worked to understand when things happened and for how long: When did plate tectonics begin? How long ago did the Earth form? How old is that volcano? How long does it take to make mountains? Some minerals in our rocks contain radioactive elements, making them geological clocks. In this talk, I'll discuss one such mineral, zircon, that has changed the way we understand the timescales of our planet, and is the time capsule of our planet's history.

Plate tectonic theory is the paradigm of the Earth Sciences, and is the lens through which we interpret billions of years of geological history. However, there remains considerable uncertainty over when plate tectonics began, with many researchers suggesting that the early Earth (>2.5 billion years ago) was too hot for plate tectonics. Furthermore, the details of what came before, and what mechanisms drove the transition, remain contested. In this talk I will provide an overview of these debates, prior to describing how one rock sample from Arctic Canada has changed this global debate forever.

Earth is the only habitable planet in our solar system thanks to its oxygen-rich atmosphere and oceans. However, the rocky interior of the Earth is also surprisingly rich in oxygen, so much so that it is out of equilibrium with our planet's central metallic core. How did the chemistry of the Earth's interior come to be so oxidised and what does this mean for the evolution of our planet and the origins of life? In this talk, I'll discuss Earth's formation from primitive meteorites and the chemical reactions that allowed our planet to develop into the oxidised, habitable home it is today.

As part of the Creative Reactions project, these artists will be presenting their artwork inspired by the research of speakers in this talk series. The artwork will also be on display at our Creative Reactions Exhibition at St Barnabas Church, 24 - 25 May.