But that’s the foreland, you traitor!

It’s been a year since I posted! Well, that’s what happens when you’re in the lab for 10 months with nothing overly exciting happening! But I’ve been freed from the lab bench and allowed to venture into the outside world, for it’s fieldwork season!

In June, I had the great opportunity, thanks to the Tectonics Studies Group, to go to on their 2015 field workshop to the Outer Hebrides! I’d never been their before so I jumped at the chance and I’m so glad that I did. The geology was just as excellent as the company on this small workshop.

As a little bit of an outline, I work on the Caledonian rocks of Scotland. That is, the rocks that were deformed and metamorphosed during the Caledonian Orogeny that occurred as the three continents of Laurentia (Scotland, Greenland, Eastern USA/Canada), Baltica (Scandinavia), and Avalonia (England, Wales, parts of western Europe) collided between 500-400 million years ago.

However, the geology of the Outer Hebrides is in what’s called the ‘foreland’ to the Caledonian Orogeny. These are the parts of the Laurentian continent that were too far removed from the collisional centre to be affected by the orogenic cycle observed in other parts of Scotland. But because they haven’t been affected by the Caledonian orogeny, they have preserved a record of much older events in the Laurentian continent, and that’s fascinating in itself!

The Tectonic Studies Group annual field trip this year, led by Lucy Campbell of Leeds University, was in the Outer Hebrides, and what a place for it to be! The trip consisted of a northward traverse through the length of the Outer Hebrides, focussing on the fault rocks and pseudotachylites within the Archaean Lewisian Gneisses that outcrop on the archipelago.

After a rather long and bumpy ferry from Oban to Castlebay on Barra, the fieldtrip started on a high, with some truly excellent pseudotachylite outcrops on the south coast of Barra.

Pseudotachylite in south Barra

Certain members of group were very excited to see some solid outcrops after the choppy crossing:

First outcrop of the week!

Although not as excited as Lucy when she saw this great outcrop almost entirely composed of pseudotachylite in NW Barra, not to mention the blue skies and beautiful white-sand beach!

A whole outcrop of pseudotachylite

Of course, being a metamorphic geologist, I greatly enjoyed finding these lovely garnets with decompression-related plagioclase coronas in an example of the Scourie Dyke Swarm near Tarbert!

GARNETS!

The field discussions as to the origins of these mid-to-lower crustal fault rocks was a fascinating insight for anyone interested in the way stresses propagate through the crust, with many an interesting point being raised from breakfast to evening beer time!

Some very deep discussions by the sea!

Despite a packed schedule, we managed to persuade Lucy to take us to the fantastic Standing Stones at Callanish – a truly amazing place to be the day before the summer solstice!

Standing Stones at Callanish

Although perhaps the BGS’s John Mendum was a little overwhelmed by the experience…

this is no time for yoga, John!

After the return ferry to beautiful Ullapool, and an eventful drive back to Oban, including an attempted rescue of a baby deer from the middle of the road near Ballachulish, some members of the party were treated to a day’s geologising on the island of Kerrera.

Despite the lack of pseudotachylites, the varied geology was more than enough to keep the remaining group interested. After the excitement of the tiny ferry from Oban, we arrived on Kerrera in style

That's the ferry?!

Here, instead of the Archaean Lewisian gneisses of the Outer Hebrides, it was the Neoproterozoic-Cambrian Dalradian Supergroup that reigned supreme, with some fantastic folds and cryptic reverse graded beds leaving us scratching our heads for a few minutes!

unf, check those folds!

Also on Kerrera, is a fine example of the Dalradian-Old Red Sandstone unconformity, an important relationship helping to disentangle the end of the Caledonian Orogeny in the Silurian/Devonian.

Dalradian-ORS unconformity

Yes, there’s a hammer for scale in there!

Other Spectacular outcrops on Kerrera included this Paleogene dyke cross-cutting Devonian columnar-jointed basalts:

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All in all, a very memorable and geologically fascinating trip to the Outer Hebrides and a short jaunt to Kerrera – two areas that I had little knowledge of, but have a renewed interest in!

Of course this fantastic trip wouldn’t have been possible without the tireless efforts of Lucy who made the trip run so smoothly; so thank you to Lucy and the Tectonics Studies Group! What a fantastic trip!

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Another summer’s over, and what have we done?

For me, the summer is over. I’ve had a good old break from desk and lab work, with a few weeks spent in my favourite part of the UK.
I’ve been in the Northern Highlands of Scotland on fieldwork this year, as I’m still working on last years’ Shetland samples, there was no need to go all that way again. There’s nothing more depressing than a summer without fieldwork however, so I managed to squeeze myself into someone else’s fieldwork, and sampled some rocks that I’d been thinking on working on for a while – as I was up there anyway!

I’ve had a fantastic time, and this made me think about what actually makes a good field trip? In my opinion, there are several factors that can come together and make a good trip fantastic, and here’s a list.

1) The geology

This should really go without saying, I am a geologist after all, but this is, and always will be, the number one thing to make me happy in the field. 

Yes, I know that what ‘good geology’ is, will vary from person to person, but I’d go as far to say that Scotland has enough variation to keep everyone happy. 

We saw some cross-bedded sandstones that are over a billion years old: 

Cross bedding in a Loch Eil psammite

Some massive garnets in the Ben Hope Sill:

Ben Hope Sill grts

The Sgurr Beag Thrust in outcrop! (above the pencil is one of the most important tectonic breaks in the Caledonides):

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Not to mention some really sexy boudinage:

Beautiful!

Beautiful!

2) Food (and drink!)

I love seafood. And at this time of the year, you’d be hard-pushed to not find some good seafood on the northwest coast of Scotland! It’s important to be properly nourished in the field and there’s nothing better than a good chowder, or seafood platter. We definitely eat well when on fieldwork!

Pic belongs to Anna Bird. Grin belong to me.

Pic belongs to Anna Bird. Grin belong to me.

Being geologists, we did partake in a few alcoholic beverages of an evening. It would be rude not to really, when the ale is so good and the whisky is excellent!

The Scots know how to make a good ale, that's for sure.

The Scots know how to make a good ale, that’s for sure.

3) The weather

What can I say? I am only human, after all. If there’s one thing that can put a dampener on a trip it’s the weather. Highland weather can be very fickle, and I’ve had more than my fair share of wet days in the field, but this time it was glorious. And I don’t just mean for a few days; it was like this the whole time. It’s the first time I’ve ever come back from the Highlands with a shorts-hiking boots tan line.

The single cloud on the day I collected from near Loch Fannich:

Bloody weather...

And a shot of (L-R) Rob, Rosie, and Anna on the way to look at some outcrops at the beach north of Durness: 

This really is Scotland, I promise!

Bringing me to what I see as the absolute most important thing for enjoyment on fieldwork (after the geology of course)…

4) The company

People are important, and the company we keep on fieldwork can make or break a trip. I’m very lucky to have had fantastic company on all of my PhD related trips, and this time was no different. Two of my supervisors (Rob Strachan and Anna Bird), a soon-to-be masters student (Rosie), and myself – a real winner for stimulating conversation and good fun, both in the field and the barroom.  

L-R: Me, Anna (with Mjolnir the Sledge), Rob, and Rosie.

L-R: Me, Anna (with Mjolnir the Sledge), Rob, and Rosie.

 

 

 

 

 

 

 

 

I’m sad to not be in the field anymore, but it has really re-enthused me to get back into the lab and answer some questions, and that’s the thing I love about geology. It’s easy to lose sight of the bigger picture when you’re cooped up in the lab all winter, but as the old adage says: 

‘You learn geology through the soles of your boots, not through the seat of your pants’

But I have a question for you: what makes a field season for you? Is there anything I’ve missed that you could’t imagine fieldwork without?

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Structural geology. It’s like Cluedo with less murder.

In the summer, I went for a walk along the coast near where my folks live in South Devon. While I was there, I noticed some rather spectacular geology, so photographed a few bits of it while I was on my walk. I was initially disappointed because had neither my notebook or compass-clinometer and therefore couldn’t do any in-depth geology, except for in a ‘oohh, that looks nice’ kind of way.  As I walked along the coast, I noticed that things were starting to get complicated, so I took the photos and then went back to my walk, in the knowledge I’d think about it more later.

Now, in December, over 5 months after actually looking at these rocks, I have a bit of time to think about the history in a little more depth, giving them the true attention they deserved. I was right, it wasn’t as simple as I’d originally thought and a little geo-detective work was needed to untangle what was going on. 

I was walking along the coast on a gorgeous July day and saw this fantastic outcrop. Obviously I had to stop and snap a picture as it seemed to be showing ‘S0’ which is the original bedding surface of these rocks before they were metamorphosed by the first stage of deformation ‘D1’, which formed the second planar surface, ‘S1’. Notice that the original bedding surface and the deformed surface are slightly oblique to each other? That’s because of the stress direction of the deformation event that created the S1 surface. I’ve marked on the photo below my interpretation for this outcrop, although feel free to disagree with me, as I’m no structural geologist by any stretch of the imagination! 

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After this, I was enticed to carry on walking down the coast to see if there was anything else I could learn about what had happened to these rocks. I know I’m a nerd, but go with it. 

So a little further down the coast I came across some rather interesting structures called en enechelon tension gashes (outlined in blue). These showed me that there had to have been a second stage of deformation, ‘D2’ which was shearing the rocks in a direction that was oblique to the first stage of deformation. Wow – two deformation phases within 20 paces, I was starting to enjoy this walk more and more!

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A little further along the coast, after being licked to death by a large Golden Retriever, I saw some lovely folding so again snapped a photo, thinking that they followed the same deformation style as the previous outcrops I’d been looking at.

But the more I looked at the folds, the more I thought there was something wrong with my initial interpretations. The folds were clearly affecting the ‘S1’ surface, but the axial planes (shown by the dotted lines below) were perpendicular to the S1 surface. This means that the principle stress direction had changed, and that there was a third deformation event affecting these rocks!

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Well, that was fun. And all of that was seen in a really short distance – maybe 1km at the most. After this the outcrop became confined to large cliffs and the tide was coming in. I also needed a little bit of time to contemplate my findings with a biscuit and some tea (very essential walking provisions), and then carry on my walk along a rather nice part of the South West Coast Path. Well, it’d be rude not to on such a lovely day – and I certainly had a lot to think about!

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How I came to realise that things take time – a PhD journey

 I started my PhD in September, and as I finished at work last week for Christmas I found myself contemplating at my desk what I had achieved in that time. And of course, where the time had gone! It feels like (and is!) a long time since I made a blog post, so as I now have some free time, I thought I’d let you know what the starting few months of my PhD was like: what triumphs and traumas have occurred, and how I’m getting into the swing of being a fully fledged research student. 

To do this, I thought a ‘day in the life’-esque post would be fun, but then I realised that most of my day consists of tinkering with excel spreadsheets and drinking tea with the ‘occasional’ trip to the lab, so perhaps that wouldn’t be overly exciting. (For evidence of excessive tea-breaks, see below – a text stream from my office mate)

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 But apart from that, what do I do with my time that warrants 8am-7pm days? Well, geochronology takes a lot of time, so it can feel like an eternity of preparation before you can even think about getting near a mass spectrometer, never mind getting an age!

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This preparation includes crushing, sieving, XRF-ing whole rocks, mineral separation, in my case – this means hand picking fresh minerals by hand with a pair of tweezers. An extremely laborious and potentially soul-destroying process if you sneeze and the wrong moment.  

XRF, that’s X-Ray Fluorescence Spectrometry, preparation is quite fun, though. It involves melting your rock into what is essentially lava (I know, very cool!), and then squashing it into a glass disk in order to analyse major element oxides such as SiO2, MgO and Al2O3. below is a picture of one of my sample glowing white-hot in a platinum crucible just before I squash it into a disc. 

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Then of course, you have to undergo chemical separation and purification of the elements you want to analyse, to reduce mass interferences when inside the mass spectrometer. This means column chemistry, which takes a long time, but I find really interesting. For a fun, and unnervingly accurate poem about the woes of column chemistry: http://blog.eag.eu.com/isobloke/a-geochemistry-ditty/

Then, if the Geochemistry Gods have smiled on you, It’s time to load them into a mass spectrometer and cross everything in hope that the samples run well, and the standards give the right value. Would you like to see a mass spectrum from the TIMS machine that my samples are analysed in? Of course you would! (who wouldn’t?)

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Unf. Just look at those peak-flats. Ahem, sorry. 

All this work for just one single isotope ratio. Why do I do it?

Maybe I’m crazy but I love it. Even though I’ve had a few disasters (some of my samples seem to defy the laws of physics and fractionate heavy isotopes before lighter ones…), but at the end of it, I know something about these rocks that no-one else does. I know when and (hopefully!) how they were formed. It’s a learning curve, and I’m already becoming competent in the lab to know when things are going wrong and what to do about it. And surely that’s one of the reasons for a PhD, To become a competent researcher? 

So I might not have any new ages after 3 months of work, but it doesn’t matter overly. The process is as important as the results at this stage. 

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Hillswick: a cautionary tale of the ups and downs of geological fieldwork

I’ve just come back from sampling various Caledonian rocks in Shetland for the start of my PhD. 10 days in that gorgeous little archipelago, which nestles quietly between the Atlantic and the North Sea. 

One of the aims of the field trip was to collect samples for geochronological analysis from a little peninsula on Mainland Shetland called Hillswick. Mostly because there were reports in the early literature of massive garnets from there, and that’s one of the main focuses of my PhD. And with a geological map that looks like this, how could I refuse the challenge?

Myself and one of my supervisors, Anna, went there for just one afternoon initially. But surely one afternoon isn’t enough to sort out such a mess? Of course it’s not, but a few things clouded our judgement that day. 

Firstly: the midges

Anyone who has ever done any living, walking, camping, working etc in Scotland at this time of year will be familiar with the Highland Midge. For those who haven’t, they look like this:

They are bastards. They’re small, swarmy, and like to eat poor unsuspecting geologists alive. I was clearly unimpressed by the little beasts in Hillswick, here’s an extract of my field notebook, complete with squashed midge (I draw you’re attention to the title of the page).

Secondly: Space Dementia

People all have different names for this, but Anna called it this, and it just stuck. I’m sure everyone has experienced it, but this was my Hillswick experience of it. 

We had been rained on heavily, it was humid, and warm (for Shetland), and critically there was no wind. We had to dodge some rather fierce looking cows, and plough through a field full of wet knee-high grass. Half way through the field something snapped inside me. 

In the rain, being eaten alive by midges, in knee-high grass to the sound of distant cows I just stood there and laughed. For 10 minutes. 

Space dementia – it’s like cabin fever, but for geologists. 

Thirdly: RiP hammer

Like my sanity, my trusty Estwing hammer didn’t make it out of that field alive. I realised when I got to the next outcrop and realised I needed something a little more delicate than the 14lbs sledgehammer we also had with us. 

But I wasn’t going back to that field. Who knew what mental or physical torture would await me…

We found some OK samples, but nothing too spectacular.

 A few moderately garnetiferous amphibolites (see above), but none of the massive garnets we’d been expected. So we went dejectedly home and made a rather large hole in a bottle of whisky. (see below, evidence from the following evening)

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A few days later, we’d recovered from the Hillswick trauma, and decided to give it another crack (now that the windspeed had increased somewhat). 

We picked up another hammer, avoided the strange farm animals, defied vertigo on the sheer cliffs, and eventually found what we were looking for. 

 

Beautiful, beautiful garnets! The geology of Hillswick is so bizarre that I have no idea what age these garnets will give. Who knows whether they’ll be 1.2 billion year old, or 430 million years? I guess I’ll find out. 

But one thing’s for sure. I’m glad I went back, despite the stress. 

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An update and an advice request

Over the last few weeks, I’ve been thinking about what to make a blog about. I’ve been to a fantastic conference, and been on some very enlightening fieldwork. However I feel that one of the most important things that have happened to me in the past few weeks has been the official transition from student to graduate!

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And with that, I ended one part of my university career, and met the conditions of my next! 

So in September, I’ll be going back to Royal Holloway to start my NERC funded PhD on geochronology of metamorphic rocks in Shetland.

I can’t wait to become a PhD student and entering into the academic community. I feel extraordinarily lucky to be given this opportunity and I’m really excited about starting!

Wish me luck, and if anyone has any advice for me as I start my PhD, I’d love to hear it!

 

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Cast adrift. What does a geologist do between a degree and a PhD?

I’ve finally finished my degree! Currently waiting on tenterhooks until the 13th when I find out my results and whether I’ve got the grades I need. All going well, however, I’ll be starting my (fully funded, woohoo!) PhD on the geochronology of Shetland this September, and I can’t wait!

I’m excited about having the opportunity to carry on doing what I love, with a supervisor I get along well with, in a town I know and like! But right now I feel slightly cast adrift, as I have been working hard over the last 4 years to suddenly be in the position of having nothing to do but wait.

So what are the plans for the next 3.5 months? Well happily, quite a lot! I wouldn’t want to get bored, would I?

Conferences

In June I’ll be attending the William Smith Meeting at the Geological Society and presenting my work as a poster. Keep an eye out if you’re going, and be nice as it’s my first ‘proper’ conference! I’m really excited about this as it’s directly related to my MSci research and also my PhD so it’ll be great to talk to people who get as excited about geochronology as I do. And the programme, which was released today, looks fantastic!

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(Gratuitous picture of some lovely zoned zircons to show how cool they are, although not as cool as garnets – not that I’m biased…)

So presenting at a conference with lots of famous geochronologists. That’s cool. Anything else on the horizon for my 3.5 months ‘off’?

Labwork

I have a few weeks of term left and I hope to get a few more analyses done to check reproducibility of my dates. This is largely because I had a batch of samples ready to run before I ran out of time on my project, so might as well get them run while I’m available! And the lab is getting a brand spanking new mass spectrometer next week (a TIMS if anyone is interested!) so it’ll be fun to see the effects of that on the data… And of course, I just think mass spectrometers are cool, so it’ll be fun either way!

Fieldwork

I’m heading up to the Northern Highlands for about a week in July (the week before my graduation!) to help a friend pick up some samples for her MSci project which is on Rb-Sr in the Northern Moine. Camping up in the Highlands with good company, fantastic geology and excellent whisky. What more could a person ask for?

In August, I need to collect some samples for myself. So I’ll be going up to Shetland for two weeks or so to sort out some geology and do some good old-fashioned rock-bashing wit one of my supervisors. It’ll be great to see the geology again now that I have more of an idea what is going on, and what to look for. I obviously couldn’t turn down the opportunity to see some more geology that looks like this:

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For a summer ‘off’ I have rather a lot of geological fun to be getting on with. But to be honest, I prefer that – if I had nearly 4 months of nothing but lazing around, I’d go mad, so it’s probably for the best!

I might try and get a few miles of the South West Coastal Path under my belt too, and maybe a trip up to the Lake District to try and conquer the Wasdale Horshoe if I can.

Anyway, fingers crossed that everything turns out ok, and that the PhD is waiting for me at the end of this!

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