luckily, my geo-injuries have been minor

When I first saw the call for Accretionary Wedge 55 I couldn't think of any injuries I had gotten in the field, and closed the tab on my browser and thought nothing more of it. However, today, reading some other reports of minor injuries, I suddenly remember a rock-related owie.

I was an undergraduate geology student, living in southern Oregon. My boyfriend at the time decided that since I liked rocks and was new to that part of the country he should take me on an adventure to the Lava Beds National Monument to do some caving in the lava tubes there.  As far as dates to take geologists go, this was a very good idea.

So there we were, wandering through a lava cave, the only light coming from my headlamp and his flashlight. He scampered up a small pile of lose rocks, each perhaps 10 to 20 cm in diameter, and I started to follow. However, in so doing I discovered that the density of vesicular chunks of lava is very different from the more solid rocks I had encountered elsewhere, and as a result they rocks shifted under my feet in a very unexpected manner.  I lost my balance and fell forward, catching myself on my hands.

In the process the little finger of my left hand got caught between two rocks. When I called out, more in surprise than pain at that point, my boyfriend returned to my side, asked to look at my hand to see if it was ok, and, seeing that my little fingernail had split lengthwise, and that the outer portion was pointing off at a wrong angle, decided that the time to fix it was before I noticed that it hurt, so he grabbed my hand and pushed the nail back where it was meant to be. That got me to exclaim in pain!

That pretty much cut short the adventure part of the day—instead of exploring further we went back to the visitor center, cleaned the wound and got it bandaged up.  Thanks to his prompt re-alignment of my finger nail the wound healed cleanly, and I never lost any nail, though it had a bit of a seam running the length of it for a few weeks.

Book Review: Metasomatism and the Chemical Transformation of Rock

Last April I heard about a soon to be released textbook that sounded very interesting and useful to my current research project: Metasomatism and the Chemical Transformation of Rock, edited by Daniel E. Harlov and Håkon Austreheim (published by Springer).  I checked out their web page, and saw that it would be possible to obtain a copy for review, so I filled in the form and sent it in.  In September I received an email letting me know how to access my copy on line, and I have been happily reading my way through the book (in between my other duties) ever since.  Now that I have (mostly) completed the reading, it is time to sit down and type up the review.

First of all, I am pleased to note that sometime between when last I read a textbook and picking up this one the fashions in how they are organized seems to have changed—this book starts with a chapter that summarizes what can be found in all of the subsequent chapters. I think I like this new trend, since it makes it easier for a busy person to decide which chapters they actually need to read based on what is and is not relevant to their own research.

The introductory chapter also provides a concise, clear, definition of metasomatism and an explanation of how it is both related to and different from metamorphism.  Metamorphism refers to the changes in rocks due to changes in physical conditions (primarily heat and pressure) which may or may not involve a change in composition of the rock. This is a subject I am well versed in, having done metamorphic research in one form or another for more than seven years now. Metasomatism, on the other hand, refers to changes in the composition rock due to interactions with an aqueous fluid, which picks up some elements and deposits others.  This is clearly related to metamorphism, but while they overlap, they are not the same.  It is also the major process affecting the rocks in my current research area, which is why I was so happy to see the book come out just now.

For the most part I have been very happy with this book—it takes a variety of different threads and ties them together in an easy to understand package.  Indeed, I have so enjoyed some of the discussions that I have taken longer to read the full book than I might otherwise have, since I stopped so often to look up and read references cited—something I don’t recall ever doing when I was an undergraduate student reading textbooks because they were required for a class.  

The list of chapter authors includes names that will be familiar to anyone who has been reading papers that address aspects of metasomatism (see above link for the table of contents). My personal favourite chapters were the ones on thermodynamic modelling, the effects of metasomatism on their host rocks, and on geochronology.  I found the one on thermodynamic modelling fascinating since I am already familiar with doing that for metamorphic rocks, and it was interesting to read about what needs to be considered when one assumes that the bulk rock composition DID change, as it does with metasomatism, but as it does not (necessarily) do with metamorphism. The chapter on effects is particularly useful for me because this is information I need for my current research, and I enjoyed the geochronology one because I did a fair bit of geochronology for metamorphic rocks for my PhD research, and it is interesting to see how one approaches it differently for metasomatic environments.  

I did notice some minor issues with the editing on a grammatical level, which surprised me, since I would have assumed that a major publisher would have good editors on staff whose job it is to prevent such things. They were just little things that caught my eye and grated a bit on my nerves as being awkward and clunky (I think that the phrase "…presence or not of fluids" should have been written "…presence or absence of fluids”).  However, such details do not actually detract from the content, which I am finding to be very useful.

I am also pleased to pass on the news that the authors of this book have recently presented a short course at the 2012 Goldschmidt conference.  They have shared the pdfs of their presentations for this course on line.  I would have loved to have attended the workshop, but since I wasn’t able to make it to the conference I am delighted that they have this handout available—it appears to compliment the book very well.

Three broad roads a geologist might travel during their career

There are several different paths a geologic career might take: academia, exploration, or environmental/risk. Which one is best for you will depend on your personality type.

A geologist in academia is usually someone who studies rocks to better understand the information recorded in them—how and why did they achieve their present composition and/or configuration?  They start with what they know: the rock is located here and looks like this, and extrapolate from clues within the rock to determine how it got there, and why, and when, and what happened to it along the way.

An exploration geologist, on the other hand, is looking for something (often oil or mineral resources).  They don’t know where their commodity is located, so they study locations where similar such resources have already been found to look for patterns to the rock structure and/or composition that they may be able to recognize elsewhere and so find what they seek in a new location.

The third category of geologists the environmental sector and/or risk management.  Their job is to understand the dangers which are present in our world, and look for ways to prevent those dangers from becoming problems.  They start with the facts that are known (e.g. the presence of contaminants in the ground water at point A, zones of weakness in rock that could lead to landslides, or the location of an active fault or volcano) and play “what if” games to determine how much (or what manner of) danger these present to the people in those areas.

So, which are you? Are you more interested in asking question of “how/why/when”?  Do you want to know “where”, or are you more concerned with “what if/how can I help”?

For myself I am pleased to be in the academic track—I want to better understand the world around me. I am not interested in playing games of hide and seek—I don’t even care to go shopping because I don’t enjoy trying to figure out where to find something I need is located.  Often the stores don’t even carry what I want and I waste valuable time looking for it, a parallel which is probably all too familiar to exploration geologists—not every search they undertake leads them to a discovery.  However, I suspect for those who do enjoy a good search there is an extra reward in terms of satisfaction when their work does lead them to what they seek.  

I am also far more interested in understanding how the rocks got to where they are now than I am in understanding what dangers they present to humans.  While I am very aware that it is vital that someone is working to keep contaminants out of ground water, or tracking them once they are there so that no one is using the bad water, I don’t want it to be me.  While I am grateful that I know enough not to build my house right on top of a fault zone or in the path of a potential landslide, I don’t wish to be the one who has to warn others about these dangers.  Adding in a human element presents all kinds of extra challenges and complications that I am happy to leave to others.  But my biases are not yours, and you are likely to have different interests and different reasons to find one of these paths more or less appealing than the others.

A challenging way to write

I was inspired by Ann and Chris over at HighlyAllotchthonous to try to write up what I study using a text editor which limits one to using only the 1000 most commonly used words.

Here follows my attempt to describe metamorphic petrology and 3D models of hydrothermal alteration systems using none of those words:

I study rocks that have changed because they got hot or because too many other rocks were on top of them. The bits that make up rocks can change quite a lot because of just how hot it is, and also because of how much stuff is on top of it.  Different bits of rock like to give away some the stuff they are made of when they get hotter (and/or they go deeper under other rocks), and instead take different stuff from other rock bits.  Studying which stuff appears more in one rock bit than another rock bit can tell us just how hot or how deep the rock must have been. 

Another thing which can make rocks change is water. When hot water moved through the cracks in rocks it can help carry stuff between the rock bits.  My job today studies rocks that had water help them to change, and I am trying to make a drawing that shows all of the changes as they happened-a drawing that one can look at from any side: top, bottom, left, right, front or back. When the drawing is done you will be able to turn it any way you want and see how the rocks have changed.

New toys are inspiring

I have always been a visual person, and one of my favourite parts about being a petrologist is the pretty photos of thin sections that I have collected.  I also love organizing stuff—I was one of those kids who had even more fun sorting my legos by colour, size, and type than I did actually building things out of them.  However, until this week, it had never occurred to me that it would be possible to do visual organization of my photos.  Oh, sure, I had some organization of my sample photos—a folder for all the thin section photos, and sub folders for each sample. Another folder for photos of drill cores, with sub folders for each drill hole, and under those more sub folders for each box of core (since when using my phone I need to take nine photos per tray of core in order to photograph every bit of it.

But that was where my organizational system stopped.  If I wanted to do something like, gather together all of the rhyolite samples and look to see if they were similar or different to one another I would open the spreadsheet of samples, sort by rock type, then, one sample at a time go through the folder of photos for each sample, import it into my drawing program, add text, insert a new page for the next sample, repeat.

Then I read a blog post by my favourite medieval textile scholar describing the photo organizational database she uses.  She mentioned that one can store photos in a folder yet, at the same time, have “albums” to organize them, and the possibility of one photo belonging to more than one album, without duplicating the photo. Her description of being able to define smart albums based on key words associated with the photos caught my attention, so I went off and got a copy of the program.

Doing this has really re-inspired me to work. My partner and I recently bought a house, and a rather large part of me had been resenting “work” as something that was interfering with important things like getting the house unpacked and organized, and exploring the forest outside of our door.  But now I am keen to come into the office and play with my photos and organize them. I am actually looking forward to writing papers, because choosing the right image to show the feature I describe in the text will be so easy with this tool.

So far I have created albums for each drill hole, and sub albums within the drill holes for the individual samples. I have copied all of the notes I took for each sample into the album description, so I can see at a glance which phases are present, what rock type I assigned the sample to, where the sample comes from, and so much more.  I am adding key words to my samples so that I can later ask to see all photos containing feldspar, or pyrite, or whatever, and I will get them.  The program lets one select multiple photos at once and apply key words to them all at one go, which saves time.

One bit of advice if you decide to do something like this:  Decide on your key word pattern as early as possible.  My photos are marked with a variety of types of key words, and my first attempt I just typed in useful words like “PPl”, “XPL”, “folded” “Qtz”, “10X” etc. But then I realized that one can add key words from a drop-down menu, which is sorted alphabetically.  After I made that realization I added a type code to the front of the key words, and now I can specify if the key word is a “drill hole”, the “scale”, a mineral (“min”), a phase that only shows up in this sample as inclusions within another mineral (“inc”), the rock type, structure, or any number of other categories that I will come up with later.  This makes choosing the keywords much easier, as they are now grouped together, so I can click on the one I need.

Importing Air Photos into Leapfrog

Some time back I received some air photos of the region I am currently working in from one of my colleagues. Last week I discovered that it is possible to easily import those photos into the program Leapfrog and thus see the lay of the land with respect to the locations of the various drill cores. However, he gave me six different photos but I only received corresponding “.tab” files for three of them. It is the data in the .tab files that tells the program how to import the photos—where are they located.  Therefore I set myself a quest: work out how to create .tab files for the other photos.  Having learned a number of things in the process, I thought I would share them here.

Step One in the process is deciding what points you want to use as markers.  Choose a place on the photo that is easily recognizable (like a cross-road intersection).  Then open GoogleEarth in one window and the air photo in another (using two monitors at once really helps!).  Zoom in to the selected location in google earth, and click on the thumb-tack shaped icon to get a marker. Drag that marker to where you want it, and give the marker a name (such as “T-intersection, upper left corner of Airphoto_a.jpg”), and save the location.  You can now look up the latitude and longitude of this point by clicking on it and selecting “properties”.

Step Two is to use an on-line form such as this one  (option: “Transverse Mercator Calculator”) to convert the latitude and longitude into the Swedish national grid known as RT-90 (that is the format of the drill hole locations with which I am working—if you are working in a different area you will need to instead convert to the appropriate coordinates for your area).

Step Three is to determine the X-Y coordinates on the photo itself of the selected location.  First look up the size of the photo by importing of it into Leapfrog without worrying about the fact that there is not yet a .tab file for it.  Then right-click on it to open the properties dialogue box and make note of the photo size (mine happened to be 1404 wide and 940 tall). (It is a good idea to now delete the photo from Leapfrog, since it is not, yet, in the correct spot). Now that you know the photo size that Leapfrog will be using, import the photo in CorelDraw, and change the size of the photo to those values.

Now you are ready to for Step Three itself: Use the “guidelines setup” dialogue box of CorelDraw to create two guidelines, one horizontal, one vertical, both located at zero. Then turn on the “snap to guidelines” feature and set the photo so that the upper left corner of the photo is located at the newly created 0,0 intersection.  At this point it is a good idea to “lock” the layer the photo is on so that you do not accidently move it during subsequent measurements.

Now that the photo is properly positioned drag new guidelines onto the photo such that they intersect at the spot you selected in Step One. Re-open the “guidelines setup” dialogue box and edit the position of those lines to the nearest whole number (e.g. 57.3456 becomes “57”) and look at the revised position to be certain you are happy with the location of the intersection of the guidelines.

Step Four: edit a .tab file with the numbers determined in Steps Two and Three.

The files he gave me have this format:

****************************
!table
!version 300
!charset WindowsLatin1

Definition Table
  File "airphoto_kriberg_a.jpg"
  Type "RASTER"
  (X,Y) (A,B) Label "Pt 1",
  (X,Y) (A,B) Label "Pt 2",
  (X,Y) (A,B) Label "Pt 3"
  CoordSys Earth Projection 8, 112, "m", 15.8082777778, 0, 1, 1500000, 0
  Units "m"
 ****************************

Where X and Y are the east and north coordinates of each spot in the RT90 format (Step Two) and A and B are the positions on the photo itself (Step Three).  Edit this to have the numbers you determined above, and repeat for two more spots on the photo.  Save as a .tab file in the same folder as the photo itself.

Step Five: import into Leapfrog.  If you edited the .tab file correctly choosing the “import image” option will open up a dialogue box that shows a circle, a square, and a triangle each superimposed over the photo on one of the three points of interest you selected. If they are in the correct spot click “ok” and your photo is imported.  If you don’t get a dialogue box but only an error message one possibility is that you could have introduced a blank space after the coma and before the next number. This is easily solved by deleting that space.

There may well be a simpler way (more automated) way to create .tab files for importing air photos into Leapfrog. If anyone knows of one do please share in a comment.  In the meantime writing down what I did will help me remember next time I need to do this.

Tasmanian Metemorphic Geology; It is wilder than you think.

This morning I received comments from reviewers on the manuscript I recently submitted.  I was delighted to see that they recommend that the article be accepted, after minor revision.  Even more than that, I am very happy that one of them took the time to actually read the text closely enough to catch some important typographic errors.  Of all of them that he found, my favourite is:  "...rocks wildly distributed throughout Tasmania". 

While, I have, on occasion, used the term “in the wild” when referring to rock types I have personally seen on a outcrop in the field (as opposed to in a rock collection in a lab or museum), I am quite certain that what I was thinking when I typed that phrase (and must have thought I saw on every subsequent re-read of the manuscript) was “widely distributed”.  My thanks to this reviewer, and to all reviewers who take the time to be certain that such errors never make it to the published version of a document.