EPSS Colloquium winter-2016

History of the geomagnetic field: what do we know and how do we know it?

The Earth’s magnetic field is generated in the outer core through motions of the conducting liquid metal. Most models of this so-called ‘geodynamo’ require the existence of a solidifying inner core to drive convection. Constraints on when the inner core began to form depend on estimates of thermal conductivity of core, but recent computational and experimental studies predict very different ages ranging from less the half a billion to nearly two billion years ago. Because of the assumed connection of the inner core to the generation of the geomagnetic field, records of the geomagnetic field, in particular the strength of the ancient field, through time could, in principle, allow us to date the timing of the formation of the inner core. I will discuss the experimental requirements of studying past field strength and what if anything can be learned from the large and growing database of paleomagnetic data through time.