Professor Andy Biggin

Palaeomagnetic records may be unique in the Earth sciences in giving us direct observational evidence regarding deep internal processes occurring back into deep geological time. The Earth's magnetic field exhibits clear variations on timescales of millions and even billions of years that signify changing conditions in the planet's core and mantle. I am interested to try and explain these variations in terms of mantle dynamics and core evolution. My group is developing palaeomagnetism as a tool for telling us, not only about fluid flow in the outer core, but also about mantle convection from the bottom-up through documenting and interpreting its influence on the geodynamo.

The geomagnetic field's strength and morphology has varied considerably even on the timescales of human history. The field is presently weakening at a rate of a few percent per century leaving our technology increasingly vulnerable to harsh space weather events. Studies of recent variations can tell us about the dynamics of the geodynamo processes operating the Earth's core and additionally warn us about how the field may change in the near future. I am particularly interested in studying very strong fluctuations in the strength of the field that are increasingly evident in archaeomagnetic records from the last few thousands of years.

Some of the oldest rocks on Earth retain a palaeomagnetic signal that can be demonstrated to be as old as they are. The Earth was a very different place 3.5 billion years ago, when the rocks we are working with from the Barberton Greenstone Belt in southern Africa acquired their magnetisations. We know very little but the mantle was much hotter and the core was probably still entirely liquid. Palaeomagnetic studies of these rock provide a unique opportunity to constrain conditions deep in Earth's interior in the Archaean Aeon and thereby to document our planet's evolution.