Farewell

This is the last post I will be doing for this course.

It has been a wild ride and I couldn’t have done it without the help of my beautiful daughter, Lauren. It is her artwork that has been featured at the top of most of the posts.

I have considered the different ways in which we interpret  and process information and tried to have something for everyone. Music, visual artistry, virtual kinaesthetic  – trying to get you all out there hands on with the Earth and exploring the emotional links provided by the sounds. You can look into this further if you explore the cognitive sciences.

I’ll leave you with one of her images exploring the relationship we have with nature. Artwork © Lauren Delora Sears.

 

Ignimbrite on Eigg

Today’s song is Turn to Stone by the legendary Joe Walsh

Artwork © Lauren Delora Sears

Wow, this is the penultimate blog for this semester!

I have to return to my favourite topic in geology. Volcanism!

Back in my second post,  “Not just another brick in the wall”, I discussed some of the rocks you can see in the buildings around Dunedin. One of my all time favourites is ignimbrite. There is something particularly spectacular about the idea of an incandescent cloud rushing down a slope at speeds of 300m per second.

The Taupo Volcanic Zone has the world’s highest output of rhyolitic rock.  Over the lat 2 million years a minimum of 10,000 cubic kilometres of magma has erupted from the zone and the signs, in the central North Island, are everywhere. Pyroclastic flows – the red hot mix of particles and air eventually come to rest, settle and weld together to form the ignimbrite.

Landsat of Lake Taupo : credit Nasa World Wind

Volcanic rocks are classified according to the amount of silica they contain. The light-coloured, rhyolitic rocks erupt at around 600-800 º C . All rocks derived from rhyolite such as obsidian, pumice, ignimbrite and pitchstone have the same chemical composition. So obsidian which has cooled very quickly forms a glassy texture.  Pitchstone is very similar although it has a coarser texture as it cooled more slowly. This gives the crystals time to grow.

Over on the Isle of Eigg in Scotland a flow previously considered to be lava has been reinterpreted. The Sgurr of Eigg is famous for its pitchstone and now it is thought to be ignimbrite. Part of the difficulty is in distinguishing between the two in the field and under a microscope. The flow shows some evidence of rheomorphism which are flow structures common in ignimbrite.

Scientists from the University of Glasgow have examined the deposits and think that they may be part of a larger complex which extends out into the North Atlantic.

Having just spent six months over in the area I am excited about the prospect of going for a visit next time. The Sgurr of Eigg is a famous landmark and I’m keen to lay my hands on it.

What on Earth is Kieselgur?

As a person keen on rocks it was a surprise to me that they use certain types of rock in the process of making beer.

It may seem odd for someone that doesn’t drink whisky or beer to be writing about these in my blogs but there you go! I don’t like the taste of either and I much prefer cider and wine although I’m trying to give up. This weekend will be an exception though as we slide into that heavenly state between sheer terror – trying to meet our deadlines – and the inevitable sickness that will follow. I reckon we have about 3 days before it all goes pear shaped.

My daughter arrives this afternoon from Christchurch and I have barely even seen her since she came back from Australia. It is quite hard when you’re a mum. For years you have been there and then, when they leave home, you spend some time figuring out the rest of your life.

Well I did that and now it is really hard on my family. I have a long distance relationship with my partner who is lucky to even get a Skype call from me once a week. I feel like I have abandoned everyone and everything else.

It has certainly been a wild ride this semester. The brain doesn’t work quite as well as it used to. And it is noticeable. When it creeps up on you it is almost imperceptible (boiled frog syndrome). But, when it happens over a shorter period of time it is downright scary.

I have two pictures in my head much as you would if you had a snapshot of your children ten years apart. Except that these snapshots are inside my head looking at each other and comparing notes. The me, that was then, is laughing. Smug in brightness of youth, the young me knows nothing of the time ahead, the trials and tribulations that lie in wait. The old me (the one now), looks back and wonder what happened. When was the change? The percentage of material that goes in one ear and out the other without stopping for a brief pause on the way through,is mind boggling. Literally.

Having a sieve for a brain has its downsides. Especially on a course like this. I have to work long hours into the wee hours, or longer, almost every day just to keep up. I have learned heaps but the question is will I retain it? I think about my younger me, still laughing, still oblivious. If only there was some way to reach back through the years and tell her…

In the meantime, there is another great thing that has come from this madness, besides the great people here, and the fun projects we have had the pleasure of trying. I have almost kicked the habit. Honestly, I don’t have time. And I need every one of those brain cells. I try to keep them like prisoners inside my skull but they are always looking for a sneaky way out.

So this weekend, with my daughter and my partner coming down, I’ll indulge to celebrate the end of a hard semester. But during the week? No more.

I’ll leave all that stuff to my partner, who is fond of both whisky, and beer, and still has enough brain cells for the both of us.

So what about this rock?

It is diatomaceous earth also known as diatomite or kieselgur. I have known it from my geology classes but I didn’t have a clue that it was involved in filtering beer. Diatoms are single celled algae that incorporate silica into their shells. When they die their bodies form the soft white rock.

It’s also used in flea powder, as a desiccant and bug killer. Maybe that’s another good reason not to drink beer.

 

Header picture credit: http://www.diatom.org

Singing Sands and Syria

Today’s song is the fabulous Leona Lewis singing Footprints in the sand. Live!

Artwork © Lauren Delora Sears

 

One of my fondest memories is of a trip we did to Turkey and Syria back in 1996. Yes that long ago! We had our three daughters with us aged between three and thirteen years old.

We did all the touristy things in Istanbul like the Aya Sofia,Topkapi Palace and the Blue Mosque. It is amazing just to be in a city that has been around so long that its name has changes a few times.

The boat trip up the Bosphorus should have been a relaxing affair but a certain three year old kept asking annoying questions. When we got back we ate fish sandwiches and watched the traffic stream across the Galata Bridge. Ah yes, the bridge between East and West – the whole place oozes history.

We caught a plane down to Adana, on the South Coast, and I remember thinking that it was odd to have the passengers all clap when the pilot made a safe landing. I have since learned that it isn’t the only place in the world that does that and it doesn’t mean that there was a near emergency landing!

When we left Adana we were headed for Syria on a local bus. The music is amazing, no matter which song was playing it seemed to keep beat with the bounce of the bus. It would have been an amazingly bumpy ride without it.

Given the events of the last couple of years, the time we spent in Syria, is priceless. It wasn’t the kind of holiday a typical family from Oamaru had, back then. Being a Muslim country, the etiquette between the men and women, had interesting repercussions for our daughters. We had been to Malaysia before but this was so different. Women aren’t allowed to sit next to men who aren’t their brothers or husbands so while it was fine for the younger two, it wasn’t for the thirteen year old. It was musical chairs every time we went on the bus.

The whole trip was stunning and it cemented, in us, an enduring love for the Middle East. We have been to Oman a couple of times since and the countryside is quiet and peaceful – apart from giant stinging hornets about 5 cm long!

One thing I never did get to do was go out and camp out in the desert. We did get to ride on camels and pay a fortune for the photos but camping out under stars, among the sand dunes would be a fabulous experience.

I’d love to go back to Oman, especially. Oman is one of the places where you can hear singing sand dunes. The idea of being out there for a few days and hearing the sand sing seems just so cool. It’s not new. Marco Polo was reported to hear them. It has a big deep voice, though, and sings during avalanches. The avalanches can be triggered by people walking on them. The frequency doesn’t really depend on the size or shape of the grains but the diameter. And they all stick together – all of the dunes in an area sing at the same frequency.

So how come not all sand dunes sing?

It seems that only dry, well sorted sand sings. It can be quite loud – up to 110dB. That’s about as loud as a car horn or a rock concert. You can only last 30 minutes with unprotected ears at that level without suffering some hearing damage!

The oscillation frequencies at the angle of repose (33°) are all harmonic vibrations. If you want to know more, about that, check out my other blogs. Flames Stand up for Hallelujah Part 1 and Flames Stand up for Hallelujah Part 2 

Can you tell a swamp from a fen from a bog?

Today’s song comes from Tool – Swamp Song.  Artwork © Lauren Delora Sears.

I remember my first trip to Stewart Island. We had been dreaming about it for years and the whole family had wanted to go.

Ever since the children are small we had taken them tramping.The eldest of our three girls had regular overnight trips. Back then, there was no Kathmandu clothing stores. If I wanted it I had to make it myself. It wasn’t the done thing to be taking young children out into the wilds. Some of our friends and family thought we were mad but, for us, it seemed pretty natural. After all, babies are extremely portable and it doesn’t take long for them to become accustomed to sleeping in strange and often uncomfortable places. Which is more than I can say for some adults.

The second time we flew in and landed on Mason Bay. The beaches are spectacular and the peaceful surroundings is nothing short of idyllic. Apart from the sandflies, of course.

These holidays I’ll be returning to Stewart Island. This time without the kids.

I have been bemoaning the lack of exercise, lately, due to the nature of the study I’m undertaking. So my partner has kindly organised a trip around the Northwest Circuit. By all accounts it is relatively straightforward for someone with the level of tramping experience that I have. Nevertheless, there is the mud to contend with. Mud and I have never really got on ever since my early tramping days in the Waitakere ranges in Auckland. If there is a chance of me ending up on my backside in it, I will. Goodness knows how I survived the Dusky Track, in Fiordland. Mind you, eighteen months ago I was a lot fitter.

So we’re off for two weeks R&R in the middle of next month.

I started to wonder why it is that Stewart Island is so famous for its mud? Everyone who goes there talks of its bogginess. Is it different from other wetlands? Come to think of it, what is the difference between a swamp, a bog and a fen?

It’s something I haven’t really thought about before; one soggy patch of ground seems much like another. Especially when you’re up to your shins, or worse, in it.

Apparently, different wetlands have different geology, topography, water regime and levels of acidity and nutrient levels.

Swamps often form in depressions surrounded by slopes of adjacent land which provides a rich supply of nutrients. There are usually small streams and the water table is above ground. The typical vegetation is flax, sedges, reeds and rushes.

Wire rush credit: Lauren Delora Sears

Fens are slightly acidic and form on slight slopes or at the toe of hillsides. They are peaty because they are waterlogged and don’t have enough oxygen present to allow full decay of the plants. Fens lie in between swamps and bogs on the wetland scale.

It’s the bog that we’ll most likely encounter on Stewart Island. The island has a lot in common with the peaty, blanket bogs of Scotland. They are poor in nutrients because they usually occur on level ground or very gentle slopes and the only source of water is rainfall. They don’t support the larger vegetation of swamps and fens. You’re more likely to encounter mosses and cushion plants. In fact Stewart Island has widespread cushion bogs. And on the North West circuit there will be lots of heath plants – which is where ‘heather’ comes from. Stewart Island has a mass of granite outcrops, again like, Scotland. They often go hand in hand with peat bogs.

We’ll get to spend a lot of time up close and personal with the bogs on Stewart Island. I wonder if they ever made whisky there…

 

 

 

Rocks as grief therapy

Today’s song is Queen’s Under Pressure.

Five years ago, a light went out in my life.

I was heartbroken and lost. There was a vast expanse of future ahead and I had no idea what it would look like. Friends told me to keep moving forward but I could only look back and I knew I had to find something that would take me away from it.

So I packed up my car and started to drive. I had no idea where I was headed except that it had to be far, far away from the suffocating present. If I could drive off into the future maybe I would get there sooner, shortcut the grief process, and stave off the free-fall plunge to excruciating pain that I knew lay ahead.

I had music blaring, boy-racer style, although my stereo system was way too under-bassed. Unashamedly, I sang my heart out in between bouts of ab-wracking sobs and cascades of tears that flowed down my cheeks in biblical proportions. After 8 hours, I was gently welcomed into Nelson by soft apricot hues in the sky. They were gradually deepening, behind the hills, as a curtain of indigo began to descend on the already dark day.

Next morning, I rose to a crystal clear sky and a frost. Those are the mornings I love best – always the promise of warmth, as the day wears on, and the light turns even ordinary things into something magical. Tramping in the autumn crispness is one of life’s joys so it seemed like a natural solution for an escape. Maybe a trip up Dun Mountain, behind the camping ground where I spent the night, would offer some respite. I had learned a little about it, during a cursory foray into ultramafic rock types, in my Earth Science class.

Ultramafic, I learned, was a very dark-coloured rock containing a high proportion of mafic minerals. These are magnesium and iron. Mafic comes from magnesium and the chemical symbol for iron, Fe. These rocks originate in the mantle – that layer of the Earth which lies beneath the crust:

Earth’s layers showing peridotite region. Credit: Janis Russell

The track up to Dun Mountain was beautifully graded and I met several mountain bikers on the way up. I planned to take my time and stay at the aptly named Rocks Hut and finish off the extra the next morning. At that time of the year there was hardly anyone about once I veered off the graded path.

Higher up, the immediate landscape of tussock and rock takes on a strangely golden hue and contrasts with the dark, bush-covered hills in the distance.

The rocks are knobbly and rough and are part of the Dun Mountain Ophiolite Belt. They are composed of Dunite, a type of peridotite named after this place, which consists mainly of a beautiful, green mineral called olivine (after the colour olive) together with a little of another mineral, pyroxene.

Normally these rocks don’t appear at the surface because olivine usually reacts with water in the upper crust and is altered to serpentinite. However, a section of the oceanic crust and underlying mantle was uplifted and exposed above sea level (an ophiolite). Dunites are usually surrounded by bands of serpentinite. During the alteration process, copper atoms in the structure of pyroxene are forced out. Metals in the rock like chrome and nickel prevent plants from growing, or at least severely limit them.

Serpentinite

Coppermine Saddle en route to Dun Mountain

Ultramafic rock isn’t conducive to plant life but there are exceptions.

I sat down for an hour or so just looking at the view, soaking up the sunshine and inspecting the rocky surroundings. These rocks are such a tactile experience. Here I was, reaching through the time warp, touching a rock that was about 280 million years old. I imagined the hundreds of kilometres I had driven to get here and if I travelled the same distance straight down into the Earth I would be in the peridotite zone. The temperatures are extremely high – enough to melt the rocks, but they don’t. The pressure of the overlying rock prevents it from doing so. It remains solid but continues to flow. I guess that my friends were right. No matter what the conditions we can keep moving even if it’s just baby steps.

Then the time came to leave. I walked out and during the descent followed the transition down back into the lushness of the bush. A small waterfall stopped me in my tracks. A strange yet familiar sensation spread across my face as the corners of my mouth pushed upwards of their own accord. A cascading waterfall is cleansing and mine would be too. The escape was brief and not entirely complete but those couple of days, alone in the hills, allowed me time to sow the seeds for a different future – a future which included rocks.

 

Header photo credit: Rob Lavinsky, iRocks.com – CC-BY-SA-3.0

Forever in Amber

Artwork © Lauren Delora Sears.

Today’s song is a chillin’ Amber from 311.

I sat and watched, hands held in front of my face waiting for the inevitable. One thing’s for sure. When a Saint Bernard’s head swivels furiously, the jowls flap and contort as the edges on the outside can’t keep pace with the skin closer to the muzzle. Huge globs of frothy spit threaten to hurl themselves off at any moment. You never quite know where they will land, only that, eventually, they will.

Long-haired Saint Bernards have an added bonus. They have clumps of hair, scrunched and matted in the gathering gel, that give it texture, substance and stickability. Finally, one sailed past me and adhered itself to the wall about a metre above my head.

“Phew safe”, I thought. For now.

Funny as it seems now, I miss those dodge-the-bullet games. I can’t believe it was so long ago. She’s gone, now, of course. Her name was Amber.

We named her as an eight week old puppy and I was made aware of a controversial book, written by Kathleen Winsor some forty years earlier, called Forever Amber. It caused a furore back then, and for some time after, and spawned a whole generation of girls to be named after the main character – Amber St Clare. The story was less well known by the time we named our pup but it intrigued me why you would want to name your daughter after such a woman.

Since then I have always thought of both of those Ambers whenever I hear the word.

In recent times, though, I have come to think more about the other kind. Just the other day I read about a team of Otago scientists who have discovered many new species of insects, spiders and roundworms embedded in 25 million year old amber. It’s a first for New Zealand since the only other southern hemisphere discoveries of that type have been in Australia.

Kauri gum is a resin which oozes from trees. It’s generally called copal while amber is fossil resin. Because it is so sticky the likelihood of things being found inside it is high. The idea of inclusions is common in geology. Quite a few things can become trapped inside a mineral – other minerals, gases, water or other fluids. In the case of amber they are small, once-living bodies, perfectly preserved.

In the northern hemisphere amber has been a prized gem since the Mesolithic period, around 8000-2700BC. Most of it has come from the Baltic coast, which lies between Central Europe and Scandinavia, and it continues to supply the majority of world. A whole room full of ornate amber panels was installed in Catherine Place in the 1760s. Unfortunately, it didn’t make it through the second world war unscathed but it has since been rebuilt and was completed in 2003.

Here in New Zealand, the stories of the gum diggers are legendary. They worked in the late 1800s, often in swamps, to retrieve the precious gum but it stopped in 1905 when trees were becoming too damaged.

Amber is often associated with lignite coal deposits and that’s exactly where the researchers found it. Kauri forest used to grow in the south and a number of its inhabitants are now encapsulated in the golden resin. Scientists will be able to directly examine a small part, of the the biodiversity contained within those forests, millions of years after their demise. What an amazing thought!

Flood – When a five hour journey turns into twelve

Song for this week is Tool’s Flood.

This week, for the second time in two weeks, I had to make the trip between Christchurch and Dunedin during a severe weather warning.

At the start of Easter, my classmate and I left Dunedin and headed for Christchurch. It was the start of a ten day break and we were both looking forward to going home to be with our partners. I was staying in Christchurch but she was flying out in the very early hours next morning bound for Sydney.

I picked her up just after lunch and we began the five hour journey by car. There was a severe storm approaching, and we had been warned to take it easy, but I have driven that road many times before and it didn’t really faze me. Rain had been plummeting from the sky for several days, on and off, and the ground was pretty well saturated. Tiny creeks, at the side of the road that were usually barely noticeable, frothed in a cappuccino cascade. The waves crashing in on the stretch of beach at Katiki were wind-whipped and wild so we stopped, very briefly, to try to take some pictures. Not a chance! Gusting gales and horizontal sprays of rain and sand on my lens, forced a hasty exit. The rain had plenty of time since it wasn’t due to get dark until 7pm. We’d be well home by then since I was happy to drive slowly and carefully and have several stops. Or so I thought.

Approaching Hampden, a small settlement between Palmerston and Oamaru, we noticed a line of traffic ahead of us. It looked like an accident or something further along the road so we waited patiently in the queue. We watched the traffic continue to come towards us from the other direction for about fifteen minutes. That seemed odd. I switched off the engine and we waited while the traffic behind us backed up. Still, the opposing traffic seemed to flow freely. After another ten minutes, we saw a bedraggled man wandering down the full line of stationary traffic towards us. One by one, the windows of the cars in front of us rolled down and he leaned in for a few seconds to speak to the travellers inside. Then it was our turn.

“Bridge is closed at Maheno”, he said. Then he added, “Can’t go back to Dunedin either”.

The Kakanui River had flooded, yet again.

Records of flooding on the Kakanui go back to 1868 and, back then, damage extended over a wide area and people lost their lives. Its catchment area is almost 900 square kilometres. One quarter of that is in upland mountain areas with steep sided slopes and the river runs in a single thread or is slightly meandering. The steep ground means that more water runs straight off over the surface (runoff) rather than soaking in (infiltration).

Drainage Basin System credit: Andrew Bennett

Low rolling hills and valleys make up the remainder. They have gentle gradients and the river channel migrates and braids. On gentler slopes there is more infiltration than runoff – unless the ground is already saturated and can’t take any more. Rainfall is measured in mm and the highest recorded during a storm is peak rainfall. Flooding is the catchment’s natural response to a deluge of rain.

Hydrologists are interested in the characteristics of the river when it floods. The discharge is the amount of water flowing through the river at a given time and it is measured in cubic metres per second (cumecs). The highest discharge resulting from a storm event includes the water, sediment and other matter in the river. This is called peak discharge. Plotting this information on a hydrograph gives a sense of what is happening over time. The rising limb is the time that the river is experiencing increasing discharge. The receding limb shows the reducing discharge and return to normal flow.

Storm Hydrograph credit: Andrew Bennett

The time from the first rain drops to the time there is a change in the discharge is called the river’s response time. If rain keeps falling discharge keeps increasing and bankfull discharge is the maximum amount of discharge that a river can hold before bursting its banks.

The problem we faced was that there was a lag time between the rain falling in the catchment and the time of peak discharge. The rain had been falling there for a while before we left Dunedin.  It takes a while for the high flows to propagate downstream from the upper reaches. So flood alarms are tiggered when the rainfall at Clifton Falls in the Upper Kakanui reaches 40mm in 24 hours and there are several stages flood warnings depending on flow. Civil Defence is notified when it is flowing at 267 cumecs at Clifton Falls as this will be much greater downstream where State Highway 1 crosses it at Maheno. The road is closed once it reaches 420 cumecs here.

The Otago Regional Council graphs show the rainfall and flow at Clifton Falls Bridge and the summary of flow for that week showed a minimum flow of 6.3 cumecs and a maximum of almost 580 cumecs. No wonder we couldn’t get through! It would take a while for the river to recede.

Apparently, the traffic that had been driving past us had been either local residents or fed-up folk who had pulled out of the line. Every now and then the cars would creep forward to take up the vacant space.

Hampden, on Easter Friday, is not the best place to be trapped by rising floodwaters. The phone signal was intermittent but I managed to check traffic updates. It looked there would be an update within a couple of hours. Luckily, we were able to pull out of the queue once the car reached a small side road. We got out and went off to explore Hampden’s culinary delights and returned to watch a couple of sitcom episodes on our laptops.

Time was marching on so Elsie ventured out in the wet to check out the situation. We were told the road was closed until midnight. Waiting in the car for that amount of time was highly unappealing and it meant we’d get in to Christchurch just before 4am.

No question –  we had to have a plan B.

“Are you up for an adventure?”, I asked.

“Sure”, was the reply.

I phoned my partner to find out the state of the Pigroot – the route from Palmerston through to Central Otago – an enormous detour but doable. He said there was some flooding but that it was still open. If the road opened at midnight we’d still have 8 hours of sitting around in the car and, personally, I’d rather be driving. It would take us at least 8 hours from here so we bolted for Palmerston.

We travelled inland through to Alexandra, past the Clyde Dam to Cromwell and up through the MacKenzie Country to Tekapo. Once we got near Alexandra, the rain eased and from there the rainfall was sporadic. By the time we got to Tekapo the skies cleared and we saw the new moon shining brightly. We made a small detour to stop at the Lake Tekapo for a few minutes to watch the moonlight reflect on the water and highlight the top of the hills behind the township.

Back on the road, it wasn’t long before the murk again filtered through Burke’s Pass. From here, the journey home was wet and miserable as we veered away from the shelter of the hills and ever closer to the East Coast.

Bleary-eyed, I pulled into the driveway just after 1am. We heard later that they had reopened the road at 8.30pm and we may have made it home a little earlier but I was pleased to have been doing something active rather than sitting and waiting.

While it is an inconvenience to be held up because of flooding it is important to take care. Thank goodness no-one has been lost recently although a woman was rescued from her car after being swept down the river as we were heading north!

I guess more flooding is something we’ll have to get used to, given the prediction of increased storminess, due to climate change. Understanding more about rivers and flood dynamics can help with travel planning at the very least. We’ll know for next time.

Checking out the long legs of liquid gold

Artwork © Lauren Delora Sears

Today’s song couldn’t really be anything other than Whiskey in the Jar by The Dubliners but it highlights the different spellings of whiskey (in the song) and whisky (in this post). The Irish spell it with an ‘e’ to differentiate it from Scotch whisky which is produced in Scotland under a myriad of rules and regulations. Needless to say, I felt compelled to stay true to my Scottish roots by referring to whisky.

And it seems that, if you’re Scottish, you are highly likely to have whisky flowing through your veins. In fact, it appears so common to love the tipple that I sometimes feel I’m the only exception!

The alluring, and seductive, liquid gold takes pride of place at tables in pubs and living rooms across the country – and the world. Sensory exploration of its nuances in character can keep whisky buffs entertained until the wee hours. I have seen that first hand. Like most things, people have personal preferences and whiskies are usually classified according to geography and flavour characteristics. Yet, even though I don’t like it at all, I have come to be able to recognise basic divisions according to how it looks and its aroma.

In actual fact, we use our senses of sight, smell, touch and taste, to evaluate whisky. And usually in that order.

Whisky is essentially a mix of flavoured water and alcohol. One of the first things a whisky drinker does, after checking the colour, is to swirl it in the glass and observe the formation of whisky ‘tears’ or ‘legs’.

Whisky legs. Photo credit: tienvijftien

Legs are drips, that flow downwards from a ring of clear liquid on the inside of the glass, above the surface of the whisky. They’re also known to form in wine. The length of the legs gives an indication of  alcohol content and they are created by the difference in surface tension between the two liquids.

Surface tension is caused by the tendency for molecules at the surface of a liquid to stick together (cohere) strongly. These cohesive forces are shared between all the molecules but, because there are no molecules above them, the ones at the surface bond with those alongside even more strongly. This is especially true for water molecules.

The increased bonding forms a line of resistance just like a row of people with linked arms. Just as you would huddle tighter in that row to prevent anyone breaking through, the surface of the water contracts. That is what is responsible for the spherical shape of water droplets. That extra resistance on the surface is also what allows water striders to walk on water without breaking through and sinking.

So, as the whisky in the glass is swirled, a thin film of the mixture is pushed up the side of the glass. Water and alcohol are both evaporated from the surface of the glass but alcohol is evaporated faster. This reduces the alcohol concentration of the film and a greater proportion of water is left on the glass.

Since water has a higher surface tension than the alcohol, and the bulk of the mixture, more whisky is hauled up the side of the glass, creating an upwards flow. The water at the top of the film beads, at first, then starts to flow downwards back into the whisky as gravity takes over. The higher the alcohol content of the whisky, the more easily and further the water can pull the mixture – hence longer legs. This phenomenon is called the Gibbs-Marangoni effect after Italian physicist Carlo Marangoni and American physicist Josiah Willard Gibbs who both worked it in the middle to late 19th century.

The alcohol content also affects the texture or feel in the mouth. If it is high, it can dry the mouth and be considered fresh. Whisky with lower alcohol content covers the mouth with a smooth, viscous coating. Although I must admit, I think I’ll leave that bit to someone else!

Seeing Mountains through a Microscope

Today’s song is from the harmonious Civil Wars – Oh Henry. Artwork above © Lauren Delora Sears.

As I get older, I appreciate the white space more and more. Designers know that the white space is as important as the rest. It provides context, balance and a container in which to arrange the content so we can easily find and navigate through the important stuff. The white space in our lives gives us room to step back and reflect. And it is this process of reflection that consolidates our learning and sparks creativity.

The hustle and bustle of life in the modern world barely offers a nanosecond of time for reflection. We rush from one thing to the next, be it job, project, relationship or adventure – always focussed on efficiency, productivity, utility and economy. It is hard to imagine a world where you had the means to pursue a career entirely of your own choosing, and construction, with little regard for the mundane necessities of ‘real world’ existence that plagues us all. The freedom to follow your heart or intellectual curiosity is a precious gift which is rarely afforded to us.

For academic researchers, the importance of this freedom and time for reflection is embodied in sabbatical leave. The notion that it was a frivolous exercise and a complete waste of time has been raised several times throughout history. But it is often when reaffirmation and rejuvenation take place. The loss of such a crucial part of the research process would be lamentable. Increasingly, research is expected to become more applied. With limited funding available for science research there is an expectation of a payoff. And sooner rather than later. So something has to give with the burden of administration, teaching and research all competing for time. Dr Tamson Pietsch notes that many researchers now do research in their leisure time.

The demands placed on the scientific research process by the modern obsession with utility and economic evaluation could have a profound effect on our ability to adapt to a rapidly changing environment.  This myopic vision reduces research diversity and alters the process and direction of intellectual endeavour.

I see this appropriation of scientific potential and subsequent loss of diversity as akin to a population bottleneck. There are many instances where the value of particular research has not been realised until much later. It takes time to acquire knowledge, build upon it, reflect upon it and stimulate creativity. As Dr Pietsch points out, fishing for ideas is like fishing for trout – it takes time. You can’t force creativity no matter who is doing the table thumping. So in the event of a concentration of research in favoured areas the ability to switch focus, and resources, will be compromised.

Fortunately for us, there have been individuals throughout history, who have had the time for research and reflection without some of these constraints. Their contribution to science today is immense largely because they were not hamstrung by bureaucratic, political or financial impositions. They were known as gentlemen (they were usually men) of independent means. Included among them was the famous Charles Darwin (evolution).

But another, hardly known outside of geological circles was Henry Clifton Sorby.

In the year that Queen Victoria became monarch of the United Kingdom he was only 11 years old. By the time he had turned 15 he was already determined to pursue a life in science.

In a bittersweet turn of events, Henry’s father died, leaving Henry a sizeable sum. It was enough, in fact, for him to become one of those gentlemen of independent means at only 21 years old. It is hard to imagine your average 21 year old, these days, choosing to pursue a life of science, in their leisure time, when such a windfall comes their way! But that is precisely what he did.

Marine science, geology and metallurgy fascinated Henry. He sailed around the North Sea coast indulging his interests in marine biology and geology. He’d collect small marine organisms which he then meticulously prepared and mounted on glass slides. Henry soon realised that the microscope could also be used to view rock samples in a very different way.

First, he pioneered the techniques for examining rock in thin section. It is now the standard method by which geologists come to understand the origins of rocks. For Henry, it would have been a laborious task, hand grinding the rock down to slices “1000th of an inch” thick. This allowed light to be transmitted through the previously opaque rock, revealing detailed structure and micro-textures.

Thin section showing aligned minerals in the structure of the rock © GNS Science.

Poor old Henry was initially laughed at for attempting to view ‘mountains’ under a microscope. However he persevered and thank goodness he did! He went on to find microscopic fluid inclusions within the mineral grains. These tiny bubbles of liquid or gas are trapped within the mineral, at the time of its formation. They provide clues to the temperature and pressure conditions which existed at that time. His pioneering work with the microscope laid the foundation for modern petrography – analysis of those detailed structures and textures.

A modern petrographic microscope, used to look at thin sections, is different from the standard microscope that biologists use. The petrographic microscope has the addition of two polarising filters, oriented at right angles to each other, and a rotating stage which the sample sits on.

Cross polarized light © Olympus Microscopy

 

Light, travelling up from the its source at bottom of the microscope, passes through the first polarising filter before reaching the sample. Only light vibrating in a direction aligned with the polariser is allowed through. This is called plane polarised light.

Thin section under plane polarized light © GNS Science

 

A second polarising filter is located above the sample and this can be turned on or off. When it is turned on the plane polarised light is blocked (crossed polarised light).

Thin section under cross polarised light © GNS Science

Olympus Microscopy have a good interactive tutorial that allows you to play around with changing the angles of the polarising filters.

Rotating the stage makes some minerals appear black briefly when the polarisation prevents the light from getting through. Some minerals produce beautiful, vivid colours caused by interference during refraction of the light rays through the mineral. By careful examination of each mineral’s different optical properties geologists can begin to reveal the composition and origin of the rocks.

Vivid colours produced by interference © GNS Science

Present day geologists owe a great deal to the efforts of Henry Clifton Sorby and others who were lucky enough to have time to think and pursue their interests at their leisure. And we all can appreciate the artistry and histories revealed by Henry’s unwavering commitment and passion for his science.