Anna Bidgood

Anna Bidgood

Anna Bidgood is a geologist and PhD Researcher from the University of Oxford, where she studies continental subduction processes in the Indian Himalaya. Listen to the wonderful stories from her fieldwork stories in Episode 3 of Fieldwork Diaries, and read her biography below. You can also find her on Twitter at @AKBidgood.

As a child, I was brought up with a family who love the arctic. The birds, the plants, the geology, the history. So it was not surprising when I managed to persuade my dad to take me on one of his expeditions to Greenland when I was 15 years old. This trip, in contrast to our family holidays in a tent in central Iceland, lead me to develop a love of the outdoors and the natural world. I was particularly interested in the geology of Iceland which ultimately inspired my decision to study Earth sciences at university.

Sermilik is the Greenland word for Icefjord. When the tide goes out, these icebergs can be stranded on the beach. A maze of ice!

Right from the beginning, my interest was in rocks and what they can tell us about the earth. ‘Fair enough’ you may say, for someone studying geology. However, you’d be surprised at how many earth scientists don’t actually look at rocks. For me, being able to find out about so much history from one little thin slice of rock is quite amazing.

I studied for my undergraduate degree at Oxford University, a beautiful city and a great place to live. As part of our course, we were required to undertake an independent mapping project for 6 weeks, anywhere in the world. Although Scotland is cheap, nearby and has incredibly geology, i didn’t fancy plodding around in the rain and bogs for 6 weeks, as many undergraduates end up doing. I decided that I wanted to go somewhere exciting and came up with the idea of going to South Greenland. Many people told me ‘it’s never going to happen’, or ‘all undergrads say that and end up in Scotland’, which made me all the more determined to see it through! This project was an amazing experience with beautiful scenery and many minerals that I’d never heard of in a layered alkaline igneous intrusion. Despite this challenge, i discovered that mineralogy and petrology were fascinating to me and that I would like to study rocks in greater (and finer) detail, influencing my decision to do a metamorphic petrology masters project and ultimately PhD.

My undergraduate mapping team, just off the plane in Narsarsuaq, taking a closer look at the glacier.

Fieldwork has always been an important aspect of research for me. Although I like to study these rocks on the microscale, where these rocks fit into the bigger picture and their relationships with each other is an important consideration. I’d gained a variety of fieldwork experience during my undergraduate degree, including working with a mining exploration company in the Peruvian Andes and as part of the team mapping areas of British Columbia with the Geological Survey of BC. So naturally, I was searching for a PhD project with a significant fieldwork aspect. 

Getting around in British Columbia is made much more simple with the help of a helicopter. We flew along a drained lake, fed by a carving glacier with our excellent pilot.

My love of mountains, cold places, camping and the rocks that you find within mountain belts didn’t quite prepare me for the realisation that I could work in the highest mountain range on earth: the Himalaya. Next thing I know, I find myself trekking around above 5000m with a team of pack horses!

Pack horses crossing a 5000m pass in Ladakh, Himalaya. We tried to keep up with them but at that altitude we couldn’t even keep up with the Tibetan Nomad showing us the way.

So what do I actually do? The Himalaya is the type example of a continent-continent collision, where India is still colliding with Asia. When an ocean meets a continent, due to it being more dense, it can be subducted into the mantle beneath the continent. However, when two continents collide, neither of them wants to subduct, resulting in a crumple zone where the continents fold and thicken. However, in Northern India, right next to the Asian continent, there are rocks which record evidence of very high pressures, deeper than the base of the crust. This tells us that the edge of the Indian continent must have been subducted into the mantle before returning to the surface as we see today. This process, known as continental subduction, is poorly understood. In fact, it took us a while to realise that it even happened at all because physics tells us that the continents are too buoyant to subduct. 

The classic outcrop of my field area. Close to the road and spectacular. Not surprising that so many geologist come here, grab a sample and leave.

Subduction zones are mysterious places. We can use a variety of techniques to determine what goes on down a subduction zone but the key to this mystery is in the rocks themselves; I am looking for evidence of the subduction of these rocks to mantle depths, as well as trying to figure out their geological history. When did the new minerals grow? At what depth? How did they return to the surface? In order to answer these questions, I had to collect samples from all the different rocks types in this area to look at in the lab, and understand their relationship to each other in the field.

I hope that my research will further our understanding of continental subduction, as well as give us more of an insight into what goes on down a subduction zone.

A buddhist festival sprang up next to our tent in a little nomadic valley. There were 200 nuns on bicycle who’d cycled from Kathmandu and Ladakhi and Tibetan people in traditional dress.
Milking of the pashmina goats. Pure pashmina comes from the beard of these adorable little goats which the nomads farm in the hundreds and follow out on the hillsides all day everyday!
Follow Us!

Get the latest posts delivered to your mailbox:

Scroll Up