Aragonite on top

Divide and rule. An old slogan, but still going strong. If you want to encounter the caving group at much less than normal strength, introduce a squeezy cave. A schism is unavoidable. This was perfectly illustrated this week: the enigmatic Bunkers Cave, which would not be too enigmatic to cracks like Dave, was the goal of the week. And the dimensions of this ungoogleable spelunk were such that mentioned gentleman arranged a dichotomised trip into a mine too. I like both! But we had done a mine the week before. I was going to squeeze with Richard the racing snake.

Underneath an impressive starry sky we walked the fields to the badger-hole entrance. And Richard snaked through. It was squeezier than ever! But it was fun. I followed on the seemingly impossible route, which ended with some birth reenactment that took me minutes. This left us in a very low room with nice dripstone formations. When we had all made it through we explored a bit further, to where this cave really showed its gems. Strange roses of aragonite crystals! I had never seen something like that.

Richard as he snaked on in front of me

I had a ball in the narrow passages

The main room of the cave

Richard had brought his serious camera

Modestly lit dripstone formations

My flash was a bit too much for this small cave, and I was out of slave flash assistants. The PCG's favourite flasher is Neil, a fact the group's website already bears witness to, but he's also one of the bellwethers of squeeze-antipathy, and  hadn't needed much time to decide he was off with Dave into the mine that day. The gods of fate, however, seem to stick to the Dungeons & Dragons adagium of "never split up", and most likely punished all separatists with a serious cold, delivered by means of sverdrups of ice cold water in the mine of choice. But that aside. I soon decided to restrict myself to my camera and a small LED torch. Enough for some really nice pics!

It's a small cave, and claustrophobics shouldn't go there, but it was really special, and I didn't regret my choice at all. Even Neil started doubting when he saw the pictures!

Margot’s science outreach: monsoon!

I used almost 2000 words in the first science outreach blogpost, about my first article as a first author, which dealt with the background of my thesis work. I here bet I will need much less for a public version of my first article that actually dealt with the monsoon. The official reference is: Saher, M.H., Peeters, F.J.C. and Kroon, D., 2007. Sea surface temperatures during the SW and NE monsoon seasons in the western Arabian Sea over the past 20,000 years. Palaeogeography, Palaeoclimatology, Palaeoecology, 249(1-2): 216-228.


How do you get from two meter of mud to a 20.000 year monsoon record? The quick answer is: very expensive machines. The longer answer starts with what that “mud” actually consists of. Most of it is skeletons. Bleached, white skeletons, with gaping, toothless mouths. Serene remnants of feisty, dynamic beings. Of planktic foraminifera! What?

A live Ammonia tepida. Source: Creative Commons.

Foraminifera are animals consisting of one cell, which make an external skeleton. They come in all kinds of sizes and shapes. Thousands of different species of foraminifera live on the sea bottom, or even in tidal swamps. I’ll get to these later. Here I’ll focus on the few species that float somewhere in the sea; most of them in the upper 150 m. The so-called planktonic foraminifera. Together with all other life forms that float around, like the algae of the previous outreach blogpost, they are plankton. The most famous plankton is probably krill, but I think technically speaking it isn’t plankton but nekton, as they actively swim around. Anyway. Planktonic foraminifera; there’s only about 50 species of these. They are named after the holes in their skeletons, that in some species you can see under the microscope; foraminifera means “bearers of holes”. Through these holes they stick out their pseudopodia, that they use for catching food and such things.

For copyright reasons I direct people elsewhere for some cool pics of (dead) forams: have a look here

All species of planktonic foraminifera have their own preference of how deep they live, and in water of what temperature, and what sort of food they eat, and so on. And the brilliant thing with them is: when they grow their skeleton, the calcite it’s made of bears witness to these circumstances. One thing about the calcite (CaCO3) is that it contains oxygen, and oxygen has several stable isotopes. The “normal” isotope is 16O; 8 protons and 8 neutrons. There’s also very rare 17O, with an extra neutron, and even 18O, with 2 extra neutrons, is stable. And the fun is that due to their different masses these different atoms have slightly different properties. 16O, being lighter than 18O, evaporates easier. The ocean therefore has a higher percentage of 18O than clouds. And when clouds rain out, they preferably lose the heavy 18O. This in itself is already quite interesting; the further you go inland, the purer in 16O the rain will be, and if you for instance find some unidentified corpse somewhere you can just measure its oxygen isotopes, and that will tell you something about how far from the sea that person must have been living. But that’s a bit beside the point.

Schematic representation of the two mentioned oxygen istotopes. Source: NASA

So where was I? Oxygen isotopes. If you would evaporate lots and lots of water from the oceans, and not let it rain back, you would end up with an ocean with relatively much 18O. So where do you put all the 16O if you do that? There’s only one good storage place and that’s at high latitudes. In ice caps! If it ends up there it stays put for a while. So suppose you have 1 foraminifera skeleton from each year over hundreds of thousands of years, and you would measure the ratio of 18O and 16O in their calcite, you would see them get richer and poorer in 18O with the passing of the ice ages. And we took a few more every ~50 years instead of every single year, but the idea is the same.

Lots of 16O! In this case disguised as Strupbreen.

For some reason I'm not too sure of (maybe there are blog-reading physicists that would know!) the foraminifera (or forams,as they are colloquially known) take up less 18O when the water temperature is higher. They seem to prefer 16O, and maybe in cold water they lack the energy to be too picky, or something. Anyway, the sawtooth signal you get is not just a result of how much 16O is stored in ice sheets, but also temperature.

An effect I understand more of is more or less opposite; sometimes a foram will accidentally grab a magnesium atom instead of the more common calcium to use for the skeleton. And magnesium does not fit as well as calcium does. And at high temperatures your crystal lattice shakes and rattles so much you end up with these normally ill-fitting atoms anyway. And why that doesn't work for 18O I don't know but it just seems to be that way Anyway, the magnesium/calcium ratio seems to say something about temperature, and temperature only.

What is good to know here is that measuring the ratio of 18O and 16O in forams is much, much easier than measuring the magnesium/calcium ratio. For the former you just pick 30 forams of the same species (the same preferences!), crush them, and feed them into a mass spectrometer. Easy does it. For Mg/Ca measurement, you have to clean your samples really thoroughly. Any Mg-rich filth sticking to your foram will screw up your measurement. So you carefully crush the foram (which will typically be around 0.3 mm big), and then subject the shards to a very uncompromising cleaning regime. You keep on boiling your samples in unpleasant liquids, and picking out bits of pollution with a one-haired brush. Tedious.

The mass spectrometer on which I did all my isotopic measurements

So how does this all get us any closer to the monsoon? What is the monsoon, really? I mentioned it in the first monsoon blogpost: technically speaking it is not torrential rainfall, as it is used in colloquial speech, but a system of seasonally reversing winds. As these blow from the land in the one season and from the sea in the other, and these latter evidently bring all the moisture, these summer monsoon rains have pushed over the original meaning of the word. But we stick to the reversing winds. The location where my core was taken, the monsoon has a clear influence on sea water temperature. Coast-parallel winds combined with the rotation of the Earth make water either be pulled up or pulled down, and in the western Arabian Sea it happens to be the case that the summer monsoon winds pull water up and the winter monsoon winds push it down. And that is relevant for two reasons.

The cooling effect of the summer monsoon is really clear on this satellite image. Source: NASA

The first reason is food. Plankton is light-dependent, and can only live in the upper water column. If there’s food there all these little critters graze it away in no time. But food in the deep, and thus the dark, remains untouched, as they cannot reach it. But if the monsoon winds pull such water up, the nutrients become available. The summer monsoon season is therefore the period where there is most going on in the Arabian Sea.

The other thing is that the surface water temperature drops dramatically when this pumping starts. And that effect is clearly seen in the skeletons of the forams. Which prefer to grow then, as there is abundant food. In winter there are reasonable amounts of forams around, as the winter winds do accidentally stir some, but in the windless periods between the monsoons not much grows there.

And here comes the smart thing about my second article. What we now did is select one species of forams that mostly grows in summer, and one that grows both in summer and winter. We know how many of each tend to grow in each season. And we measured both species for 18O and 16O. And evidently, you don’t get the same results. That is, in some periods you do, but that then means the summer and winter were more or less the same. In some periods the year-round dweller has more 18O; a sign of cold winters. But the last ~8000 years, the summer dweller showed more 18O. So that was when the summer monsoon was strong enough to pump up the cold water!

The two species I used: on the left the summer bug, and right the all-rounder. Pics: Saskia Kars

And with only 18O you only know relative temperatures. This can be solved with Mg/Ca measurements. But what we then did, and that’s the smart part, we only did one species, for which we then had absolute temperatures. The temperature difference gives you the other one! Saves you lots of time and money. And in science, there is always a serious lack of both.

So what did we find? In our records, winter was colder between 20.000 and 13.000 years ago. As one would expect; 20.000 years ago, the last ice age was still ruling supremely. Between 13.000 and 8000 years ago, the difference between the seasons was small, mainly because winters were not as cold anymore. And then, kablang! At 8000 years the summer monsoon kicks in like mad. Like mad, as in, taking only a few hundred years, which we earth scientists think is really fast.

Heavy monsoon rains! Photo: the New York Times 

The fact that you see these three distinct periods, and not just a smooth increase of the summer monsoon at the expense of the winter monsoon, may indicate that there are two stable states of the monsoon system: the glacial and the interglacial state. The period in between looks like a bit of a transitional state. And the system can swap quite fast!

Monsoons are generally linked to the astronomical variability of the sun, but that is a very smooth cycle. Evidently, there are thresholds and feedbacks and such going on that moderate this forcing. And our record is not enough to unravel which ones, or how, exactly, but it in one more step in the right direction!

Ps Ha! That was only about 1650 words. I knew it! Maybe again a few hundred less for the next article…

Autumn in February

I need some fresh air to keep me going. I need some driving practice! And after that confusing Tuesday I needed to find out if my satnav had really broken with me. I went to Dartmoor. Picked a reservoir to walk to, and possibly around.

My satnav was accurate as before! I was superstitious about car-related things before, but this makes it much worse. It looks like my satnav is deadly jealous of Neil's iPhone! Or of Neil. That can perhaps be found out. But that's beside the point.

I followed a stream that came from the reservoir. And it led to misty moorland. Very atmospheric!

Beautiful how man made structures and nature can sometimes become inseparable

Two seasons in a weekend

Friday I was in the lab, and I was done with what I was doing at five. Five! A difficult time. To take up a new chore, or go to the office? I decided to do the wise thing, and not overwork, but just get some office-things done while having some sandwiches, have a quiet pint, and go home.

Entering the building I saw Roland was still there. I had something to discuss with him, so I first dropped by at his office. To deliver my message, and then fall into the trap of immediate pub-going. Sometimes it takes too little to drag me off.

Not only Roland was there. Lots of people! Nice people. New people, as well. Normally you're surrounded by Brits, but this time Roland and I, while talking English, were immediately recognised as Dutch by a passing Belgian, who introduced us to his Dutch PhD student with his equally Dutch girlfriend. And later I ended up playing (very crap) pool with three Frenchmen, one of them also being a protégé of the Flemish guy. The latter by the way confirmed Sinterklaas actually visits Plymouth!

Do I have readers who don't know where this is going? Probably not. The beer went like a torrent into my very empty stomach. I don't even know when I left. And I came to regret that the day after. It was an enchanting spring day, and I don't even like spring! But I was in no shape to enjoy this unusually pleasant vernal interval. I was in a perfect shape to lay on my couch and decide I was a jerk who got into her own way. Such a day! And would the evening before have been any less fun without alcohol, or at least with moderation? Not very likely. I still haven't learned. Ah well.

I did drag myself out, trying to find materials for a superdeluxe mining lamp. One of the cavers is a light technician who is willing to help me rebuild an old club light into something state of the art! And probably an old club lamp would do the trick quite well, but I'm fascinated by this possibility of touching on the processes behind. And I ended up crossing town from south to north and west to east, but I found nothing of the materials I was looking for. At least I found fresh air and a lovely sunset.

I was supposed to go onto another drinking spree that night. I don't think so! I heard through the grapevine that the French were tougher than me, and all three showed up, but I admitted defeat, and went to bed early.

The next day spring was gone. We got autumn in return. The season of repentance? Redemption? I don't know, but it fit quite well. I decided to sharpen my car skills, and check if my satnav would have come to her senses. In other words: go to the Moors. But I think that would be a new posting. This is getting long!

And maybe this posting will reassure some people. I already got comments my blog nowadays is all about science, caving and the Moors, of which only one is a social thing, and that that strongly contrasts with my blog as written in Norwegian times. Which is true! But here finally something about people and alcohol. Followed by a hope that next time I can restrict myself to people, science, caving, and the Moors...

Iron

It all started in a uranium mine. And then several copper mines followed. But an iron mine, that was new! And perhaps for a reason; the iron mine we cavers would visit was quite far away.

I spoke of my enthusiasm for the next caving trip at lunch, and our new PhD student, Marta, was interested. And she's not English, so she was eager to try this new challenge out at the first opportunity. The good thing is that everything gets better with good company. The bad thing (or actually good, in the shock therapy sort of way) is that she lives in a narrow-roaded part of town. As if Neil wasn't bad enough.

I managed to pick both up. And off we went! In the diametrically opposed way to where my satnav sent me. I don't know what went into it. I have already jestingly called it a "Neil compensator" as it allows me to navigate to caves if I'm not chauffeuring Neil (I can't read maps and drive at the same time), but it seemed that it went spiralling out of control when confronted with the combination of both. I have to find out if it would now be willing to send me in something better than 180 degrees the wrong way, but Tuesday evening we were rescued by what might be the cause of this disturbance. Neil masculinely took out his iPhone and directed us. Really gloating in satisfaction, but who could blame him.

By testosterone guidance we found the right place, and got ready for a damp trip. After a nice walk to the nearest adit it took us about 1 meter to reach water so deep it filled Marta's boots. I was wondering if she would ever come with me, on any trip, again. But we moved on! This mine had been in use between something like 1895 and 1969, so it was the most recently used mine so far for me. Not that that made it any more high tech. Crude tunnels, disappearing rails, collapsing chutes, rickety timber ceilings. But an iron mine! And the uncorroded iron ore is like fairy dust. It makes everything sparkly and mystical. Beautiful!

 Waiting for Mike to open the gate of one of the adits. These are closed to the general public. Marta looking all professional up front.

 The iron lode, where it had gotten so thin they had stopped digging for it

Within 20 meters we found a spot where it became apparent that there were not only levels above us, but also below. A wooden floor with holes in it! At ground water level. And the cavers are not collectively famous for their low mass. This was OK in the beginning, but soon after it became so bad only Dave elegantly manoeuvered past, took some pictures, and got back. I was quite happily trying my new photography kit, which needs some more practice, but which makes much more things possible. And as things go, I forgot about the floor, and while discussing equipment with Dave I suddenly felt no ground below my foot. The holes! As they are water-filled not much that's nastier than getting a wet outfit, some tortured muscles, and perhaps a lost camera can happen to you. I have a waterproof camera, and was smart enough not to let go, but was still a bit stiff from Burnfoot the Horse, so I suffered no material damage but was noticeably more uncomfortable in the muscles than before. Luckily a supple, elegant gait is not a requirement for going on PCG trips.

 One of the spots with rickety floors. And notice Marta as a seasoned flash wielder!

We went in several adits, every time soon running into the dead ends of the tunnels. And having to wade back to the entrance and going for the next. One tunnel confronted us with a, fortunately very conspicuous, but also large, hole, which luckily did not stop us. Marta also negotiated it like a routinier. It was a beautiful trip!

 

Neil  practiced with slave flashes. So with a slave and a Neil one can make quite good tunnel pics!

After three adits it had been fun, and we went back to the cars. And then to the pub. To my pleasant surprise Marta joined the caving group on the spot! It evidently hadn't been that bad. And after one drink we went back. Again relying on Neil and his phone, as my satnav wanted to direct us to Exeter. Where would we, two defenseless girls, have been without a man. Next week we might find out! Next week it'll be a cave, and Neil doesn't do caves. And I hope Marta comes again! And we'll see if by then my satnav will have come to her senses again...

The unusual tthings you can find in a mine.  A rusty moped! Good for having Neil demonstrate his testosterone levels.

Rural escape

I saw it! And it's beautiful. Not bad for a temporary solution. What this is about? Roland's house! After moving they had settled in to such a degree they could start to show off. And show off they did.

I took the not-so-scenic approach, as the scenic route requires a foot (and bike) ferry and my timing was crap. So I went the long way, over the bridge. As soon as you leave town behind and farmland begins you know you're close.

Roland found me spying for the right house number, opened the gate, and showed me around. What a place! A recent barn conversion (which sounds a bit odd to norwegiophones) but nothing overly modern about it. And with a sunny terrace just beside a meadow with sheep! Brilliant.

Roland looking a bit more jaded than he really is in his brand new back garden

Nobody would be surprised that it was night by the time I left, which gave the way back extra cachet. I took the scenic route back, which mean country roads lit by nothing other than my two little LEDs and the full moon. Beautiful! Except for the steep parts down, where my eyes watered so much the view was somewhat lost on me.

Roland and Maria are very happy with this new house, and it's easy to see why! I hope I'll be there many times more. I have cumin seed cheese, that should be enough to bribe my way in at least once!

Hunting the English

The English. If you’re Dutch you grow up with them . Or rather, with an image of them. Or even better, with several images of them. There’s the bowler-hat wearing, cane-wielding, moustached gentleman that strolls through country towns and engages in friendly and civilised conversation with miss Marple-like ladies. And there’s the binge-drinking, violent, union jack-boxershorts-clad, bald and tattood, vomiting hooligan.


And if you then actually move to England, what happens then? Am I, tulip-toting and clog-clattering, chaperoned on the streets by the sophisticated gentlemen that help me manoeuvre past the half-conscious hooligans? And how does society work if females do not exist? One realises of course the miss Marple-like lady is only scenery.

Cartoons are fun, but I wanted to know more about the real English. And you can only know so much, but I saw room for improvement. I already noticed all sorts of things in daily life. Brits don’t think it’s strange to not own a bicycle, they think crisps are a lunch dish, they call dinner tea, they surrender their towns on weekend nights to hoards of scantily clad, noisy women, they only dance when they are (or are with) scantily clad, noisy, under age women, they can’t let go of their imperial units, and so on. But I wanted to read more. I tried a historic book, and the memoirs of a confused British citizen from the outer regions of the Empire, but it was not satisfactory.

Neil heard of this and said he had another book about the English. My expectations had been lowered by earlier experiences, but I gave it a try. And from the first page it was a hit! “The angry island - hunting the English”, written by an A.A. Gill, an angry, eloquent Scot, who sees things crystal clear, but who at times cannot resist indulging in spacious arrays of disparaging, contemptuous, condescending adjectives. His hypothesis is that the English’ defining characteristic is suppressed anger, and he sells this concept well.

He covers more topics. The hysterical love for animals, the impeccable talent for creating good war memorials, the inevitable queue, the strangling nostalgia, drinking habits and all other kinds of things, but the central theme is anger. And as a matter of fact, it is all indeed recognisable. Neil even agreed; “it’s all true, and it makes me angry!”

Having read this, and recognising it in society, by the way does not make me dislike the English. At all. I do think they tend to stick to a fairly monotonous life of work and family and pub, and are difficult to persuade to do something outside that small circle. Beside that, they can be a tad evasive, but that holds for most people, in the eyes of the Dutch. And they live in the 19th century when it comes to gay emancipation. But above all that my overpowering impression is that they are friendly and polite. That is, when 20-ish or older; teenagers here can be as mind-bogglingly rude as everywhere else. But just bike through town here. If you’re used to Amsterdam you’re used to abuse. And here people smile at you! Make way for you! And outside traffic as well; so often I meet kindness where I expect rudeness. And I love the downright romantic way strangers treat you here. If I buy my lunch I tend to be greeted by “how are you, darling?” from the lady at the counter, followed by a “thank you, my love” if I hand her the money. If you come to the English and don’t expect them to follow you where you go, this place is a warm bath!