Metaphorical rocks

I have been taking a language class since moving to Scandinavia so that I can learn to understand the local language. Last week we had a homework assignment to write about our new city, and there was an essay in the textbook that we could use as an example/inspiration for our own writing.

Being a geologist with little interest in cities my essay didn't look much like the one in the book, which focused on various tourist destinations in a major Scandinavian city. Instead I spoke about the fact that January was a good time to arrive here because then it is cold enough it doesn't rain, mentioning that I do not care for rain in the winter, but I love snow, and find the ice-crystal covered trees much prettier than bare trees. From there I went on to discuss the interesting people I have met, and ending with a paragraph explaining that I am looking forward to summer because then I will be able to see the rocks; I have been told that the local rocks are ______, and that is the prettiest rock type.

The word I had in that blank was meant to be "metamorphic". However, when I asked my favourite on-line dictionary for the local word for "metamorphic" it didn't know the word, so I instead called upon Google Translate, which helpfully provided me the word "metaforiska", so I used it. However, when the teacher returned my essay she wrote on the page "metaphorical? Is that really what you meant?" Oops! Checking Wikipedia the local language it turns out that the word I should have used was metamorfa.

However, when I think of it further, it occurs to me that, perhaps, I did choose the correct word after all. Metamorphic rocks, can, indeed, serve as a metaphor for life. In this world we are born as soft, yielding creatures (babies = ocean floor sediments). Over time we are subject to heat and pressure ( = rules from parents & society) which gradually transform us into first older children (phyllite) and then teenagers (low grade schist) and finally mature adults (high grade schist, mylonite, or even migmatite) with the record of our experiences both moulding who we are as people and leaving a permanent record in our souls (zoning in porphyroblasts, inclusion trails, flow banding, etc…) The more difficult the life, the more character we develop, and the stronger we need to be (which is why the prettiest rocks are the ones which are most deformed).

links to other blogs

I just read a wonderful series of posts by Life in a Plane Light describing how metamorphic reactions turn boring old mud into beautiful garnet schist. If anyone missed it, part one talks about the factors that make up metamorphism, the second talks about the first changes that happen to the mud when heat is applied, and the third adds deformation into the equation and gets us to the garnet. If you haven't read them yet they are so worth a look.

slickensides vs slickenlines

In my current job I am learning any number of interesting things as I look things up in the course of editing so as to be certain that terms are being used correctly. Today's noteworthy subject to look up is the difference between the terms "slickensides" and "slickenlines". I only recall the former from my undergraduate structure courses, and neither term has come up in my own research since then. There was a time when looking up such geologic terms meant reaching for a geologic dictionary. These days it can sometimes be more effective to reach for the internet. I just found an interesting article which nicely clarifies the difference between the two words, and why there are two such closely related words in the first place.

Slickensides refers to the planar, polished, surface of a fault plane (the polishing occurring when the rocks rub past one another. Slickenlines, on the other hand, refers to the liner scratches which occur on such a surface, as a projection on one side of the fault scratches a grove onto the other. Most of the slickensides I have seen in the field contained slickenlines. No wonder my teachers and classmates simply used the term "slicks" when discussing them informally in the field.

What an effective way to learn!

I recently replied to an advertisement looking for people to do editing of geoscience journal articles. They first sent me a one page test document to edit to see if they were happy with my ability as an editor, and when I passed that exam they sent me an actual article to do. What a fun assignment! In order to properly edit a sentence one must understand what the writer intended to convey, and in order to do that one must understand the context—what procedures did the author carry out, what were the results, and what do they think it all means? I have written before about "active" reading, and the advantages that can give one in understanding the content of a journal article. It turns out that for me I am able to get even more information out of an article when I edit it, one sentence at a time. I have sent the first article back; I really hope they like my work with it and decide to send me more. I have so enjoyed learning the topic of this paper that I wish to do it again with other papers.

what goes into making a thin section before we can do optical mineralogy?

There has been a lively discussion on the MSA-Talk e-mail list the past few days on the subject of optical mineralogy. Life in a Plane Light has a very nice summary of the discussion and an update of other posts that came in after the first summary.

I have been following the conversation with interest because optical mineralogy is very important to metamorphic petrologists. For those of you who are not familiar with the process a brief description is in order. Step one is to obtain an interesting rock from the field—break off a hand-sample from the outcrop (a chunk of rock small enough to carry in your hand), record on your map the location from whence it was obtained, and write down any important observations you have made about the outcrop (how large is it, does it contain more than one rock type? What sort of contacts separate the rock types? What structures are present? If your sample has any structures which are measurable (foliation, lineation, strike & dip of the rock itself) measure them *before* obtaining your sample, and make marks on the rock with a waterproof marker showing what you measured and what the measurements were—then carefully break that portion of rock away from the outcrop without destroying the marks.

Why is step one so important? Because knowing the field relationships of your sample really helps your understanding of what you will see in the thin section once you have it.

Step two is the creation of the thin section. To do this we use a rock saw to cut the hand sample open. If there are structures of interest in the sample (foliations, lineations, etc.) it is important to make the cut at an angle of interest. There are times when one wishes to see the minerals parallel the structure, times when one wishes to the minerals perpendicular to the structure. If the structure is complex one will likely wish to make more than one thin section of the rock at more than one angle.

We use the saw to cut a small rectangular block of rock out of the hand sample, with one of the long sides of the rectangle oriented in the direction of interest. If your sample is an "oriented" sample (it has marks on it showing what was measured in the field) take care to transfer those marks onto the small block so that you will know which way is "up" or "east" or "north", or whatever orientation you have marked. Once the hand sample is a small block we polish one side of it (the one which is oriented in the direction of interest with respect to the structure) and when it is very smooth we "glue" that side to a glass microscope slide (using a rock appropriate epoxy). At this point we record the sample name on the glass, and also transfer any marks showing the orientation of the sample to the glass itself (this can be done low-tech by scratching on the glass with a nail, or high-tech by using a laser, or with a few other options in between of intermediate technology levels) After the epoxy has set we use a rock saw to cut away most of the rest of the block of rock (which we save for later comparison with the thin section—it can be helpful to also polish the face of this block that was closest to the glass before removing it).

The next step is to polish the thin layer of rock which is attached to the glass slide. This is done carefully because at the end of the process we wish the layer of rock remaining attached to the slide to be only 30 microns thick (remember that there are 1000 microns in every millimetre). The reason we wish it to be that thin is because at this thickness many of the rock forming minerals are translucent—light will pass through them.

This is where the "optical mineralogy" part really begins. By using a petrographic microscope we can see and identify the minerals in the sample and see their relationship to one another. How do we do this? By carefully comparing the various features we can see with an understanding of the features usually displayed by minerals. A course in optical mineralogy teaches us how to distinguish one mineral from another based on their colour or lack thereof, how high is their "relief" (does it appear to stand up above the plane of the glass slide, appear to be lower than that plane, or more or less lie in the plane?), what is its crystal habit of each of the minerals? All of these clues, taken together, permit us to recognize the minerals.

Once we know which minerals are present we can then make observations of how they relate to one another. Are they all aligned with their long axis parallel to the same direction (foliated)? Is that alignment a planar feature, or is it folded? Is there more than one foliation? Are some minerals present only totally surrounded by (included within) certain other minerals? When minerals are present both as inclusions and within the matrix is there any difference between them? (are the inclusions smaller or larger than the same mineral in the matrix? Are they oriented the same direction in both locations? Is there a colour change from one to the other?

These are just a few of the things we look for in a thin section to help unravel the story of the rock. When I was an undergraduate student we not only had a dedicated course in optical mineralogy, but it was a requirement of the course to make one thin section ourselves, starting from collecting the sample in the field and ending with a report about all of the minerals present in the sample and their relationship to one another and what we learned about the rock thereby. In those days we had to make a drawing of the thin section which showed these relationships.

Now days we have fancy, high-tech optical microscopes with motorized sample stages that are attached to powerful cameras and computers. As a result we can program the machines to take a series of photographs at very close scale of thin section, then "stitch" them together to make a single high-resolution image of a large portion of the thin section, which we can then annotate in a drawing program, labelling the minerals, tracing the structures, etc. For those of us who are not practiced artists this is a much better approach for illustrating what we see in the thin sections. However, in the old days a talented petrologist with a steady drawing hand was able to do drawings of thin sections which are works of art and which show an amazing amount of detail of what is in the sample. For a good example of this check out the book Metamorphic Textures by Alan Spry, published in 1969 (ISBN: 0080133169 / 0-08-013316-9), which appears to be available for purchase in pdf form these days, though I haven't tried to do so.

serendipity

I have been in Scandinavia for two months now, and this weekend I decided that it was time to see if I could learn anything of the local geology on line, since the rocks are still too snow covered to be revealing many of their secrets to my own observations. So I called upon Google, as you do in such situations, and requested information on "Luleå geology". Much to my surprise the first hit was an announcement of a faculty position at the local university, the one within walking distance of my new home. They are looking for someone to teach ore deposit geology and conduct research on that topic. The translation of their ad says that this means that one uses "geochronology, isotope geochemistry, tectonics, structural geology, mineralogy, etc. to explain and describe the processes by which metals are transported, concentrated and precipitated".

This description made me smile; while I have not focused upon ore deposits in my own research their list of tools used is pretty much a one to one match to the list of research interests/tools on my CV. Reading the fine print of the ad I see that previous experience in research on the topic of "malmkaraktärisering" (ore characterisation) is "meritorious", rather than "required". This, too made me smile; I may not have done much with ore deposits myself, but I am a graduate of CODES: the Centre for Excellence in Ore Deposit Research at the University of Tasmania—all of the short courses and most of the seminars I attended were on ore deposit research of one sort or another, often sharing very cutting edge research or technological applications. Therefore, while I may not have the "meritorious" advantage of having done my own research on the subject, I have absorbed a fair bit of information on the topic over the years, and have a good idea of which colleagues to turn to if I have questions on any particular topic in the field.

While writing the application (read: taking information from my CV and inserting it into their template) I thought about what to put into the "future research" section of the document. This caused me to recall a particularly interesting seminar talk while I was still at CODES, so I e-mailed the speaker and let him know that I was preparing the application and would be interested in doing collaborative research using that technology should I be the successful applicant. Much to my delight I received an encouraging reply in plenty of time to include his name in the application. He also reminded me that the honorary doctorate degree he'd received a couple of years back happens to have come from this university. I am taking this as a positive sign, and happily turned in my application this morning (today being the application deadline—I saw the ad only just on time!).

I have no idea how I will do with this application—it matters as much what the other applicant's packets contain as it does what I have included in my own, but I am confident that should I be the lucky winner in this case I will be able to do the job, and do it well. How lovely it would be to be able to work in the town I have chosen for personal reasons. However, if it doesn't work out I am certain that I will enjoy whatever path I do take…

too busy too be bored; too happy in the north to want to move south

I have some friends who are unemployed and looking for work who complain on certain social media sites that they are bored. My contract ended with the end of December, so, technically, I am also unemployed, but I am far, far too busy to be bored (as people might be able to guess if they compared frequency of my posts before and after the contract ending).

What am I doing to keep busy? I'm getting close to done processing the data I generated during the last couple of weeks before I left; I should be able to actually begin the writing process within a week. I'm settling into a new home with a new partner in a new country, and trying to learn a new language. Our evenings are full with folk dance classes, choir practice, gaming with friends, visiting a local climbing wall, martial arts practice, and, of course Medieval Re-enactment. My days are full with finishing up my last research project, trying to keep up with personal correspondence, studying my new language and attending class for that, dealing with the bureaucracy at the Uni (why do they need copies of my highschool, BS, and Master's transcripts before they approve my enrolment in a beginning language class when they have my PhD transcripts? (Doesn't the one sort of imply the existence of the others?) I am also starting the paperwork for appropriate visas to actually be able to stay here.

I'm also continuing the job search, but now that there are two of us to consider I'm being a bit fussier about the jobs for which I will apply—I have never been interested in hot climates, but had been applying for interesting sounding jobs located in such places anyway, with the thought that I could endure hot weather for a short time and then when I have more experience move on to someplace with good weather. Now that I'm happily living somewhere far enough north to have real winter I am much less inclined to consider locations without winter, and my partner, like me, loves the snow and cold weather.

I listen to friends who live in more southern locations complain about winter—that it is cold, dark, wet, and depressing. I am convinced that the reason they think this is because they are too far south. Up here in the north (though still south of the Arctic Circle) winter may be cold, but it isn't wet, and it isn't dark or depressing. Instead the snow reflects light beautifully, making even overcast days brighter than their counterpart down south. And day, like today, when there are no clouds, are sometimes overwhelmingly bright. Yes, the sun does set early, but we are living in a town, which means that there are street-lights, which means that the snow is reflecting that light all night long, so visibility is good and it is neither dark, nor depressing.

I have been saying for a decade that I really miss real winter. Now that I have it again I don't wish to move somewhere without it. Now for the fun part: either finding an academic job which will let me do interesting research and live in the north (but with mountains, too, please!), or obtain funding which will let me choose my own location to live and do research…