Women in STEM: Professor Marian Holness

Professor Marian Holness leads a research group in the Department of Earth Sciences, and studies the processes which occur during the melting and solidification of rocks. Here, she tells us how time spent in quiet activities like running, knitting and even breastfeeding have helped to trigger new insights in her research.

I was educated at state schools in Southampton before coming to Cambridge, where I gained my BA and PhD. I spent six years as a Postdoc at the University of Edinburgh, and have been a University Teaching Officer at Cambridge for the last 22 years.

I am interested in processes that happen during the solidification of partially molten rock. It’s these processes, happening in batches of magma trapped under volcanoes, that ultimately control the explosivity of volcanic eruptions. The roots of volcanoes can be accessed if their tops have been eroded away, so I look at ancient volcanic regions, mainly in East Greenland and Scotland, where the rocks at the surface were originally buried several kilometres deep, so I can see what went on in the crust at that time. My approach involves careful field observation, followed by microscopic analysis of grain sizes and shapes and the ways grains fit together, to decode the solidification history.

Last summer we spent six weeks in East Greenland, working on a 60 million-year-old body of igneous rock called the Skaergaard Intrusion. I’ve been working on this for 12 years now, but on this trip, we saw masses of really novel things and I made many important breakthroughs in understanding – that was pretty thrilling.

I guide my group in their science and help them write their papers. I sometimes have time for my own research, which involves optical microscopy (I have rather less time for this than I would like!). One of the great things about Cambridge is that it has an excellent museum collection of rocks I can dip into when chasing up particular hunches and ideas. Most years I supplement this museum-based work by going into the field to collect new observations and samples – this is usually in the summer, and involves being away for up to several months though the usual time is a couple of weeks.

A key moment that helped define the development of my career happened when I was waiting for an experiment to heat up during my time in Edinburgh: I was quietly knitting a sock, watching the temperature climb on the dial… and out of nowhere I suddenly had a brainwave that made sense of everything I had been working on for the previous year. I learned from this and now find that spending time knitting, running, breastfeeding(!) and other quiet activities is the best way to trigger insights into my research.

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