Heather Howard: Geological mapping - a dream job

Heather Howard talks about how her love of the outdoors led her to what turned out to be her dream job, geological mapping in one of the most remote parts of Australia, the Musgrave Province.

Transcript

00:00 Heather

I was being paid to go to a remote part of Australia and walk over the hills and understand the rocks. That, for me, was just a joy.

00:12 Julie

Welcome to The Rocks Beneath Our Feet. In this series, five geologists talk about their years devoted to working for the Geological Survey of Western Australia. From understanding early life, to the tectonic processes that shaped our planet, and making the maps that unearth our understanding of Western Australia’s geology, they reveal their shared passion for discovering the stories in the rocks beneath our feet.

I’m Julie Hollis.

In this episode, Heather Howard talks about how her love of the outdoors led her to what turned out to be her dream job, geological mapping in one of the most remote parts of Australia, the Musgrave Province.

00:49 Heather

I’m Heather Howard. I joined the Geological Survey almost 20 years ago. I’m a geologist and igneous geochemist. Most of my survey career has been spent on regional mapping programs and geochemical studies, mostly in central Australia but also now in the Pilbara.

I think some people find being a geologist is a vocation, but it wasn’t like that for me at all. I didn't know from an early age that’s what I wanted to do. I just followed my interests. And I somehow ended up in geology. I’ve always loved the outdoors, hiking over the hills, being in nature. And I think from an early age I was quite curious about the ground I was walking on and what the rocks were made of, how they got there, what processes formed them. But my schooling never really brought that out. And it wasn’t until I went to uni and started studying geology that I realized that that was really the subject for me, because it brought together the science and the outdoors and gave that walk over the mountains another dimension.

01:58 Julie

Absolutely.

01:58 Heather

So I think after a year of studying and doing various mapping projects, I knew that was the career path I wanted to follow.

02:07 Julie

It seems to be very common, that geologists suddenly discover geology once they’re already at university.

02:13 Heather

Yeah, none of my family or friends, anyone I knew was a geologist. In England it wasn't a career, not really, not a common one. So I just didn't come across it at all. I just kind of found my way into it.

For our undergraduate degree, at the end of the first year, everyone was sent out to do an individual field mapping project, which took four weeks. And I went to a southern area of Snowdonia in north Wales and spent four weeks in the rain mapping grey, wet rocks. But I thoroughly loved it. And that was my first experience of volcanic rocks actually.

02:57 Julie

Yeah

02:58 Heather

For my honours project, I did a, a mapping project in France. That was looking at recent volcanics, so it was quite different. And that's where I got into geochemistry as well.

03:09 Julie

Yeah

03:10 Heather

I did a PhD in igneous geochemistry, and that really added another dimension to the outdoor experience because not only did I discover the processes involved in the rock formation but I started to think about what was happening in the crust and the mantle as well.

03:26  Julie

How did you end up at GSWA?

03:29 Heather

I took the leap and moved over to Australia. The geological survey seemed like the kind of place where I might find something interesting to do. I began work for the abandoned mine sites project and soon realized that regional mapping was going to be more up my street. After short while I got moved to a mapping program in the west Musgraves. And without focusing too much, I found that I was in my dream job. I was being paid to go to a remote part of Australia and walk over the hills and understand the rocks,

04:06 Julie

Yeah

04:07 Heather

That for me was just a joy.

The Musgraves mapping program, it was a regional mapping program that ran for twelve years. I think we covered twelve map sheets at one to 100,000 scale. So the mapping had been done by GSWA in the 1960s. Our job really was to go out there and map it in much more detail and use geophysics, geochemistry, isotope geology, and geochronology. Because the 1960s maps, although they were great, each map, which was essentially six times the size of one of our hundred thousand scale maps, each of those was mapped by a couple of people in one season. They certainly didn't visit every outcrop. They couldn’t possibly have done that in the time they had.

And the Musgraves is important geologically because it's a younger area between three ancient pieces of continental crust. So this was an opportunity to unlock how those ancient pieces of crust came together.

05:15 Julie

So what was your experience like that first season?

05:17 Heather

So at the start of the Musgrave project, I think it’s probably fair to say that I was thrown in at the deep end. I'd just finished my PhD not long before joining the survey, in geochemistry. And I was thrown into mapping an area that was high grade metamorphic rocks. So it was really not my area of expertise. 

05:39 Julie

Yeah

05:39 Heather

So the area just north of Wingellina was mainly sand plains with a few small hills dotted around. So we just went from hill to hill. And then after we’d done that for maybe just four or five days, my manager at the time, Hugh Smithies, said, “OK, so we’ve seen a few granites in these hills, how about you go and tackle that larger hill over there? You know, it’s fairly sizeable so it should take you a bit longer. Maybe a day, maybe a day and a half?” And I thought, Well that’s ok. We’ve looked at hills where there’s maybe one or two types of granite.

06:19 Julie

Right

06:20 Heather

I think I could maybe get over that. Maybe not in a day but maybe two days.

06:25 Julie

Yeah

06:26 Heather

This hill, it had a steep north face and the structure of the rocks seemed to be dipping to the south. So I went round to the north side thought, Ok, I can do this

06:39 Julie

Yeah

06:40 Heather

And with every step I took, I stood on a different lithology. And it just wasn't that simple. There were strongly foliated granites, mylonitic granites, amphibolites with garnet. There were rafts of banded gneisses from the sedimentary and volcanic rocks, which we later called the Wirku Metamorphics. And then on the very cap of the hill, there was this porphyritic leucogranite. But all of this was in this one relatively small hill, which on the mapping from the 1960s, that was on the map as a granite. So, I don’t want to be critical of their mapping. That was a scale issue. Those geologists covered a vast area in a short space of time and did a fantastic job with what they did. But that wasn't the scale that we mapping at.

07:41 Julie

Maybe they did go there and saw a granite.

07:43 Heather

Well, yeah there was granite there. It just wasn’t all that was there.

07:47 Julie

Yeah

07:48 Heather

So anyway, so the first day passed and the second day passed and Hugh was saying, “Ah, are you nearly finished?” It actually took me four days in the end and I felt like I left that place not really fully understanding it.

08:03 Julie

Yeah

08:03 Heather

And the hills that we went to after that were much more simple. I would see one or two of the lithologies.

08:12 Julie

Yeah

08:13 Heather

You know, just one field relationship. And after a week or so, I'd seen everything that I'd seen at that one hill. And it kind of all fell into place then. But the place we started at, that hill became known as Heather’s Hill because I just couldn't leave it.

08:32 Julie

And did you take Hugh back there sometime and show him?

08:35 Heather

Oh yeah, we went back there many times.

08:37 Julie

Right

08:38 Heather

And actually the year following that, we had a joint field trip with some geologists from the South Australian geological survey and the Northern Territory Geological Survey. The Northern Territory guys had mapped the Musgraves in the Northern Territory.

08:55 Julie

Yeah

08:56 Heather

So when they saw that hill, one of them said that that one hill encapsulated everything that they’d seen in the Northern Territory in the Musgrave Province. And I’d seen it all in one day effectively. So it wasn't really surprising that it was baffling.

09:13 Julie

Yeah, you were kind of lucky and unlucky at the same time, I suppose. It’s nice to have everything but maybe not on your first day out as a junior geologist.

09:24 Heather

Yeah. As time went on, we moved westwards and passed over one of the fairly major faults and saw the same rocks that were far less deformed. And again that was another, another penny dropping,

09:40 Julie

Yeah

09:41 Heather

I think. Yeah another look back at Heather’s Hill. 

So on Bell Rock, which is a map sheet close to the South Australian border, there are lots of ranges. The Bell Rock Range, the Wingellina Hills, the Hinkley Range. They’re large layered intrusions.

10:00 Julie

Right

10:01 Heather

Some of those are seven to ten kilometres wide in outcrop. So to map those was a bit of a challenge. And because I love walking, I found the best way to do it was to get my fieldy to drop me and then drive the length, and all the way around the other side of the range, to a meeting point. And then I would walk over the hill and meet them at the end of the day.

10:26 Julie

Yep

10:27 Heather

I imagine that some people would find that quite daunting, but there’s a moment, after all the preparation, we both know where we’re meeting and at what time. But there’s a moment when you’re left on the edge of an outcrop and you watch the fieldy drive off into the distance. I don’t know if it’s excitement, or partly hysterical panic. But that gave me such a buzz, doing that, seeing them go and knowing that I'm just completely alone.

11:02 Julie

Yeah

11:03 Heather

And in one of the most remotest parts of Australia.

11:07 Julie

Yep

11:07 Heather

And that the next sort of seven or eight hours, I would spend climbing hills, navigating over the rocks to the place before dark and trying to understand the geology along the way. And hopefully by the time I get to the vehicle safely, I've got a map in my head of what I've seen and I've connected all the observations that I’ve made. But I love those days. Some of those days were the best parts of the project I think. They were kind of a, a glimpse of what the old explorers might have felt.

11:42 Julie

Yeah. I know it’s often not like that anymore because of the way that health and safety requirements have changed, but there’s something about just being out there on your own, having this opportunity to learn something new, by yourself.

11:58  Heather

Yeah

11:59 Julie

I think it kind of gets to the heart of why people love field geology.

12:03 Heather

Yeah, I think having that space just to think through geological problems and look at the textures in the rocks and create in your own mind a map as you go is what I really love about it.

12:16 Julie

And when you have those moments, once in a while, when suddenly you actually figure out some key aspect of the geology from the field geology. It’s so satisfying.

12:26 Heather

That's right. I think it’s the discovery that drives me actually. When you gather a whole series of observations and a picture or model develops from that. For me it’s often a, a hunch that grows into something that I can eventually explain as the evidence kind of comes together in my mind.

In the Blackstone and Bell Rock areas, we’d been looking at a volcanic sequence, part of the Bentley Supergroup, and some nearby granites that showed really beautiful mingling texures with mafic magma. And Hugh made the observation that the geochemistry of the granites was the same as the felsic lavas in the volcanics. And I’d been playing around with the geochemistry of some mafic dykes – the Alcurra dykes – and I’d been able to generate the composition of the felsic volcanics through fractional crystallization modelling, of those mafic dykes, which was pretty cool. Anyway, the Alcurra dykes were dated at 1067 million years, so we knew that we had to date the felsic volcanics in the Hogarth Formation too.

So we got a sample of a rhyolite from the Hogarth. And I can remember Hugh phoning me up and saying, “Ok, we’ve got the date back for the Hogarth. What do you think it is?” And I said, “1067”. And he said, “It’s 1068.” I was just like, Yes! That’s close enough.

13:52 Julie

Yeah, I’d say so.

13:54 Heather

Those moments when you’ve pieced together the evidence from field observations and geochemistry and then geochronology and it all tells the same story are just so rewarding.

14:06 Julie

Yep

14:07 Heather

One of things about the Musgraves is that it never got boring. We began with high grade metamorphics, then we went on to the layered intrusions, and then we had a supervolcano. It was like having three separate little projects within one large one.

I think when I started this job, I realized I'm actually doing the kind of geology I experienced at university on all those field trips, I’m actually doing that for a job. I always hoped that that would be possible but I never really thought it would be.

14:36 Julie

You’ve been listening to The Rocks Beneath Our Feet. You can discover more about GSWA by visiting dmp.wa.gov.au/gswa or find GSWA on LinkedIn and Facebook. If you like what you’ve heard, give them a follow.