Friday, April 15, 2011

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).

Friday, April 1, 2011

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.