Eye Tracking Geologists in the Field


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Abstract: The history of eye-movement research extends back at least to 1794, when Charles Darwin’s grandfather, Erasmus Darwin, published “Zoonomia” which included descriptions of eye movements due to self-motion. For the next 200 years eye tracking research was to been confined to the laboratory. That all changed when Michael Land built the first wearable eyetracker at the University of Sussex and published a seminal paper  entitled “Where we look when we steer”. Inspired by Land’s work, a group cognitive scientists, computer scientists, computer engineers and geologists have been working to extend knowledge of how we actually use vision in the real world. I was fortunate enough to participate in this ground-breaking experiment earlier this year, and I wanted to share the experience with the geology community! In this blog article I will give a brief summary of the project I was involved in and the things I learned that can really help you be a better field geologist!

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How do we look at a scene?
Most animals do not simply gaze at a scene – we simply don’t have the necessary resources to take in every single thing in front of us. Instead, our brains have developed a cunning cheat system whereby we target important aspects of a field of view and build up an image in our mind from the important selected areas. The bandwidth and processing power of our eye-brain circuitry need therefore only deal with a small portion of the image at once, and lots of interpolation can be done at source in the brain. This can be illustrated in the figure below:

Fig.1 Unlike birds, most animals build an image of the field of view before them by targeting important areas sequentially.

Fig.1 Unlike birds, most animals build an image of the field of view before them by targeting important areas sequentially.

Figure 1a shows what a field of view may “look” like to our brain before any fixations are made. Using our limited understanding of this new scene our brain may then target key areas of the field (fig. 1b-c) of view for further investigation. Fixations of varying durations and acquisition order are made, allowing our brain to, in real time, develop a better understanding of what is before the eyes. This process continues and continues the longer we look at a scene.

This process has been proven to be heavily influenced by the individual. The specific way we approach deconstructing this scene depends on a whole host of factors. This could be gender, intelligence, familiarity with the surroundings, experience with the scene, state of mind (distraction, tiredness) -basically any environmental factor that can affect the brain may change the way our brain and eyes go about investigating this scene. We may therefore use eye-tracking to see how different categories of people look at the same scene. To do this, eye-tracking software can gather the following information:

  • Fixation Points
    • Location, duration, sequence, saccade types
  • Pupil Dilation/constriction
  • Blinks

Eye tracking technology is therefore a powerful tool in cognitive research that may be used to access the brain. Here are some examples of common applications of eye-tracking:

  • Commercial Applications
    • User interface design
    • Marketing and product placement
    • Targeted marketing
  • Primate/infant/adult/geriatric research
  • Safety
    • Fatigue detection
    • Concentration detection
  • Sports Training
    • Motorsports
    • Ball sports
  • Accessibility
    • Communication tools for disabled people
    • Advanced methods for computer-human interaction
  • Medical
    • Laser Eye Surgery
    • fMRI, MEG, EEG

Eye-tracking is of particular interest to the commercial sector. Interestingly, commercial applications exploit the brain and the eyes: for instance, there’s a proven reason that advertisements at the top of the google search results page cost the most…

Heatmap of fixations of a google seach result page. (http://highongoogle.net/images/seo-bolton-google-eyetracking.jpg)

So what does this have to do with geology? Well geologists are just one of many communities target by this new research. As mentioned in the abstract, eye tracking technology has only recently become mobile enough to be taken out of the laboratory and into the real world. Geologists are often confronted with new scenes in the field and must use their eyes and brains to really understand what it is that they are looking at. Therefore, by taking amateur and professional geologists into the field and conducting eye-tracking experiments, we can gain insights into differences in ways professionals and novices approach visual problems.

The Study of Geologists in the Field
A joint study between Rochester University and Rochester Institute of Technology (RIT) has for the past five years using a hefty NSF grant ($2m) to research geologists in the field. Principal investigators include Robert Jacobs, Jeff Pelz, and John Tarduno. The beautiful wearable eye-trackers were developed by Jason Babcock. The research has been conducted in a variety of environments, but the part that I took part in was a 10-day field excursion to the Western USA to visit some truly amazing geological localities.

First, lets take a look at the technology that I was wearing for the 10 days, and how it worked:

Backpack – Contains 1 Apple Mac Book Air, the powerhouse of the mobile eye-tracking unit and home to the custom-built processing software.

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Head Unit – Contains a front-facing camera above the right eye, and an eye-facing camera and IR bulb for filming eye movements. Also we had to wear a ridiculously large sombrero to shield the cameras from direct sunlight.

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Network – All the devices were connected to a local network, the router for which was being carried around here by Jeff Pelz. The custom software meant that he could use his iPhone to get real-time footage from any participants front-facing or eye-facing cameras at any time. This was useful for adjustments and also keeping participants looking where they should during experiments.

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The Vans – The network extended back to the vans too. This van was the tech-van and contained massive hard drives for backing up all the data. Each evening, the RIT folk would sit in this van and process/backup the data.

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Calibration – Each time we wore the mobile eye-tracking units, we had to complete a series of calibration exercises such that our fixations could be mapped onto the video of our front facing cameras. This was done by standing a few meters away from a calibration spot (as seen below on the back of Tomaso’s notebook) and rolling the head whilst keeping our eyes fixated on the spot. As if we didn’t look stupid enough!

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Gigapan Images – Meanwhile, other members of the tech team were taking panoramic GigaPan images of each scene onto which the tracking data could be overlaid.

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A typical stop would work something like this (somewhat similar to a roadside execution…):

  1. On approach to the locality we were told via radio not to look at the surroundings
  2. We’d get out of the vans, get the trackers on and calibrate
  3. Someone would then lead us to the viewing point – all the while we had to look down at our feet
  4. At the viewing point we would be given a question to address in our minds – often something like “What is the evidence this is a tectonically active area?”
  5. We were then told to look up and analyse the scene in silence for around a minute
  6. After the allocated time was up we then had to answer questions about what we had observed
  7. Following questions we would then be given an explanatory guide to the geology by John Tarduno

The Results
Unfortunately, I wasn’t allowed to know the conclusions of the study thus far during the trip – this would ruin the experiment. Similarly, if you ever think that you are going to have the chance to take part in a similar study – STOP READING NOW. Despite the lack of information I was privy to, I did manage to get some of the conclusions of the study from the authors before I left. What I am allowed to divulge is pretty intuitive, but may help you and even your students learn to analyse scenes better.

Put simply, professional geologists make fewer, longer and more systematic fixations when looking at scenes of interest. This makes sense – your brain targets the information in a scene that is going to tell you the most useful information to address the problem in mind: i.e. what’s the geological history of this outcrop? Conversely, the students in this experiment made lots and lots of short-lived fixations all over the scene in random places as they tried to search for something they might understand.  Here are some visualisations of the differences between students and experts.

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The locality above is in Owens Valley, CA (36.60594N, 118.07511W) – fault scarp that resulted from an earthquake in 1872. It is has ca. 15ft of right lateral slip, and 8ft of vertical slip. As you can see from the image above, the expert realises that he/she is faced with a recent fault escarpment. The expert analyses the break in slope and the presence of the boulders on the escarpment. The novice, however, sees no significant feature in the dusty ground and looks to the mountains in the distance and local hills to see if there is anything obvious. The novice’s path of fixations is chaotic and short, returning to the same points briefly for no reason, then heading elsewhere.

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The above scene is of a hanging valley located in Yosemite National Park (37.71769N, 119.64846W). The hanging valley represents the valley of a tributary glacier, and is now drainage for water. The cliff face represents the side of the valley calved by the main glacier – this main valley was deeper and so now the tributary valley “hangs”. The expert fixations for this spot are therefore right on the money. The expert looks at the slight u-shape to the hanging valley, acknowledges that there is still drainage here (reinforcing this is in some way a small valley), and the expert also notices the steep valley sides – likely caused by glacial activity. The novice however is distracted by the pretty rainbow and waterfall, and fails to see any real significant features in what to them is just a cliff face.

Summary
I had a great time in the USA taking part of the study, and I learned some new and reinforced some old really valuable field skills:

  • Make sure you do your research on the geological context of the area – we weren’t allowed to do much reading at all, and it really makes it tough when you are just dumped in a completely new tectonic/geological setting with no warning
  • Keep your eyes open all the time – even when driving from spot to spot. You should be gaining information all the time. Not being able to look around as we drove between stops was disconcerting and contributed the the difficulty of interpretation.
  • Have a question to answer in your mind – this gives the brain a guide when prioritising fixations
  • Make sure you can see properly – sunglasses and hats get distracting direct sunlight out of your eyes
  • PUT NOTEPAD AND PENCIL AWAY – just look. Sit there and just look and think. Then when you have understood more, start to draw.
  • When you see a feature you think might be interesting, feed it into your starting question: This is a bush… Does the bush give me evidence of recent tectonic activity? No. Stop looking at bushes.
  • Relate your stops to other useful resources – maps and satellite images. In the last example, it would be enlightening to see the broad and shallow valley atop the cliff.
  • If you find yourself looking all over the place – STOP. Start looking for lines and colour changes – i.e. topography and lithology changes. What are the key features? List them if you need to, even if you don’t understand their relevance.

Remember that your eyes don’t have a brain of their own. They are guided by what you know. If you don’t know anything, your eyes are not much use to you!

Thanks so much for reading! Please feel free to comment below!

#21 – Find significant relationships in data with a CoCo Matrix


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The CoCo Matrix (correlation coefficient matrix) is a script for R that takes a table headed with multiple variables and calculates the correlation coefficients between each of the variables, determines which are statistically significant, and represents them visually in a grid-plot. I created the CoCo Matrix to cross correlate a table with a large number of variables to quickly assess where important correlations could be found.

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Using the CoCo Matrix

The R file can be downloaded here or copied from the textbox at the end of this post.

  1. If you know the number of samples in your dataset (n) then degrees of freedom (df) = n-2. Use this table to find the R value above which significant values lie. In the code, at the top you should change the value of “p” as per the value you just looked up. If you don’t know the value for n then run the code once and type “n” into the console.
  2. If you want, customise the colours in the customisation area of the code
  3. Run the code. A dialogue box will request a file. Alternatively replace the code to direct to the file you want to use.
  4. Voila!

This is a very rough script I wrote, and I intend to make it a lot better at some point when I have the time. If you have any suggestions  for improvements then please comment below or get in touch with me.

# CoCo Matrix version 1.0
# Written by Darren J. Wilkinson
# wilkinsondarren.wordpress.com
# d.j.wilkinson@ed.ac.uk
#
# The "CoCo Matrix" visualises the correlation coefficients for a given set of data.
# Like-Like correlations are given NA values (e.g. Height vs Height = NA). For the moment
# duplicates such as Height vs. Weight and Weight vs. Height remain. At some point I'll 
# provide an update that removes duplicates like that.
#
# Please feel free to edit the code, and if you make any improvements please let me know
# either on wilkinsondarren.wordpress.com or send me an email at d.j.wilkinson@ed.ac.uk

# Packages -------
library (cwhmisc)
library (ggplot2)
library (grid)
library (scales)
# ----------------

# Plot Customisation ----------------------------------------------------------
# (for good colour suggestions visit colourlovers.com)
col.significant = "#556270"			# Colour used for significant correlations
col.notsignificant = "lightgrey"		# Colour used for non-significant correlations
col.na = "white"						# Colour used for NA values
e1 = c("nb", "ta", "ba", "rb", "hf", "zr", "yb", "y", "th", "u")   #  p) {s = "Significant"}
		if (temp < p) {s = "Not Significant"}
		if (temp == 1) {s = NA}
		if (temp == 1) {temp = NA}
		results[h,i] = temp
		plot.data[r,4] = s
		plot.data[r,3] = temp
		plot.data[r,2] = h
		plot.data[r,1] = i
	}

}

# Open new quartz window
dev.new (
	width = 12, 
	height = 9
	)

# Plot the matrix
ggplot (data = plot.data, aes (x = x, y = y)) + 

geom_point (aes (colour = sig), size = 20) + 

scale_x_continuous (labels = e1, name = "", breaks = c(1:n.e1)) +

scale_y_continuous (labels = e1, name = "", breaks = c(1:n.e1)) +

scale_colour_manual (values = c(col.notsignificant, col.significant, col.na)) +

labs (title = "CoCo Matrix v1.0")+

theme (
	plot.title = element_text (vjust = 3, size = 20, colour = "black"), #plot title
	plot.margin = unit (c(3, 3, 3, 3), "lines"), #adjust the margins of the entire plot
	plot.background = element_rect (fill = "white", colour = "black"),
	panel.border = element_rect (colour = "black", fill = F, size = 1), #change the colour of the axes to black
	panel.grid.major = element_blank (), # remove major grid
	panel.grid.minor = element_blank (),  # remove minor grid
	panel.background = element_rect (fill = "white"), #makes the background transparent (white) NEEDED FOR INSIDE TICKS
	legend.background = element_rect (colour = "black", size = 0.5, fill = "white"),
	legend.justification = c(0, 0),
	#legend.position = c(0, 0), # put the legend INSIDE the plot area
	legend.key = element_blank (), # switch off the rectangle around symbols in the legend
	legend.box.just = "bottom",
	legend.box = "horizontal",
	legend.title = element_blank (), # switch off the legend title
	legend.text = element_text (size = 15, colour = "black"), #sets the attributes of the legend text#
	axis.title.x = element_text (vjust = -2, size = 20, colour = "black"), #change the axis title
	axis.title.y = element_text (vjust = -0.1, angle = 90, size = 20, colour = "black"), #change the axis title
	axis.text.x = element_text (size = 17, vjust = -0.25, colour = "black"), #change the axis label font attributes
	axis.text.y = element_text (size = 17, hjust = 1, colour = "black"), #change the axis label font attributes#
	axis.ticks = element_line (colour = "black", size = 0.5), #sets the thickness and colour of axis ticks
	axis.ticks.length = unit(-0.25 , "cm"), #setting a negative length plots inside, but background must be FALSE colour
	axis.ticks.margin = unit(0.5, "cm") # the margin between the ticks and the text
	)

# Print data tables in the console
results
plot.data

#20 – In Progress: Project Lithograph


unsorted 26I’m building. Secretly building. It’s going on behind the scenes, and until now, it’s been nowhere near reality. But now I’m getting a tad excited that one day soon I’ll be ready! I’m talking about a project that has tickled my ticker for some time…

Back when I started my degree in geology, I started to collect so-called classic texts. Looking around the charity shops of affluent parts of Edinburgh, a surprisingly populous treasure trove of old geology books awaits the saturday bargain hunter! And now, I have shelves and shelves of these books looking all… well, old! But what’s the point? Sure they’re fun to read, but some of them are so old and so few that not many people have the chance to enjoy them. And how up to date is their content? Is it going to teach you something? Sure it will!

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But that’s not the point! Pick up anything written by Geikie, Miller or even Holmes, and you’ll find they’re written with utter elegance. Written like the musings of Mr Darcy in a world now so alien to most of us. Modern science writing is the aspergic younger brother of classic science writing, you know… back in the days when your papers started with “On the….” and you conducted your fieldwork in a suit followed by a trail of lackeys.

But it’s not the writing style that I enjoy most. It’s the illustrations. Maybe I’ve been looking at undergraduate field notebooks for too long, but the standard of drawing in these old books is no question, art. Also, since Edinburgh and Scotland are the home of Geology, there are so many great lithographs from around this great nation that it’s all the more fantastic to see something or somewhere that you are familiar with.

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So, I’m planning a resource. An online gallery of these images so that all may marvel at their beauty. And who knows, you may even find some illustrations that could be made use out of. I’m slowly scanning in image after image, hand-drawn maps, double spread lithographs, meticulous creations of geologists that had the time to sit down and spend half the day sketching a geologically significant scene.

Got some old texts yourself? Would you like to get involved? Get in touch and let’s do it!

#10 UHP Metamorphism, The Eiffel Tower, Queen Elizabeth’s Face, and Quartz Grenades


We’re all used to the concept of pressure, but in many different ways. Some think of peer pressure, the pressure of working life, or maybe of your ears popping on an aeroplane. For geologists however, geological pressure along with it’s siblings geological time and temperature describe conditions in the Earth which are unimaginable to most people.

An illustration of the components which determine pressure.

Pressure is a measure of force per unit area, and it’s quite easy to calculate given just a few variables (i.e. area, force, maybe acceleration too). Beyond the base of the Earth’s continental crust, these geological pressures reach 2,500,000,000 pascals or 2.5 GPa, and continue to rise the deeper you go. From this point on, a rock experiences Ultra High Pressure (UHP) and may be metamorphosed (rather than melted). It is, however, difficult to preserve rocks which have been down so incredibly deep as there are very few processes which take rocks down below the base of the crust and bring them back up to the surface quickly enough so that they preserve information on their burial history. Therefore although UHP conditions prevail throughout much of the Earth, not many rocks on the surface ‘remember’ if they were ever there. More than likely they weren’t.

The majority of tectonic activity on Earth results in rocks being sent deeper in the Earth and new rocks being created in igneous processes at or near the surface. Only special circumstances result in rocks re-surfacing after being very deep in the crust or mantle.

But just how much pressure is felt by rocks when they reach UHP conditions? Well yes we know it’s 2.5 GPa or above, but how can we relate to that? Well, to generate a UHP of 2.5 GPa concentrated on the golden face of the queen on a standard first class stamp, you would need to load that stamp with over 76 million kilograms. That’s equivalent to balancing 10 full-sized Eiffel towers on Lizzie’s Chops! Even that kind of pressure is hard to imagine, but suffice it to say you’d not want to trap your finger under that!

To generate 2.5 GPa on a postage stamp you’d need to load it with over 10 Eiffel Towers!

The photomicrograph shows a garnet crystal with inclusions of various minerals. The yellow dots show the inclusions which were once coesite, but are now quartz. The expansion f the coesite/quartz has created radial fractures in the surrounding garnet.

In my eclogites the mineral garnet commonly contains inclusions of quartz. When the garnet bearing rock experiences UHP conditions for long enough, the quartz changes its structure to a more dense form we call coesite. For the UHP rocks in my field area, these rocks inevitably start making their way to the surface. As the pressure starts to drop, the coesite inside the garnet starts to expand. Like the casing of an imminently exploding grenade, however, garnet resists the expansion. Eventually, however, the coesite reverts back to the quartz structure which takes up a larger volume. This shatters the garnet in the surrounding space just like the explosives in a grenade must shatter the casing to continue expanding.

So when I look at my rocks in thin section, I really like to think that I’m looking at tiny quartz grenades exploding on the face of the queen under the weight of 10 Eiffel towers!

#9 Thin Section Photomicrographs Using a Mobile Phone: Tips and Tricks


Like many of my colleagues, I have a lot of thin sections of many different rocks to look at. But sharing what you observe down the microscope is not as easy and convenient a process as it could, or indeed should be. When looking at sections, I make notes etc directly on my computer, and therefore I wanted the convenience of sitting at my computer rather than at a station in the microscope laboratory which is in a different part of the building.

Recently, the quality of the lenses and sensors on mobile phones has shot through the roof, and most modern smartphones now come with a pretty decent camera. Not to mention that on the same device you have the accessibility to many apps, including e-mail, via which you can share and send your images to other devices. Much easier than removing a memory card and inserting it into your laptop!

Hot To

Cover the other eyepiece to prevent entry of light from your surroundings. Then use both hands to offer the camera up to the eyepiece whilst sealing out as much light as you can.

1. The logistics of taking the photo with your camera.

Step 1
Locate the field of view you wish to photograph. Make sure that the image is in focus. You can of course take the image through either eyepiece, but I prefer using the one without the crosshairs. Make sure this individual eyepiece is in focus.

Step 2
Cover the other eyepiece to stop reflections. Light doesn’t only leave an eyepiece, it can also enter it. Light entering the open eyepiece will bounce around the optics and inevitably exit through the one that you want to take an image through causing nasty artefacts.

Step 3
If you are right handed, hold the phone in your right hand in portrait mode. It’s easier to handle this way, and the “take photo” is probably better accessed by your thumb/finger this way too. Using your left hand, shield the top and sides of the phone. This also allows you to stabilise and manoeuvre the phone into the desired position.

Step 4
Repositioning the camera takes a bit of practice but you’ll get the hang of it in no time. Firstly you want the lens vaguely in front of, and perpendicular to the image coming out of the eyepiece. You should see some sort of image appear on your screen. It will more than likely be overexposed and/or blurred. Once this image is central, using your left hand as a steady guide, adjust the spacing between your phone and the eyepiece. You are not focusing the image here, you are ensuring that the entire field of view is projected onto the camera lens equally and entirely. Too far away or too close and it will look like a small spotlight is illuminating part of the field of view, the rest of it is in darkness. As you move closer to the ideal distance, that spotlight will become large until “BAM!” suddenly the whole field of view is illuminated and you can take your picture once the camera has focused. This ideal distance is quite a narrow zone, so make sure you steady your hands and make gentle adjustments until the image is right.

The image shows what you expect to see at various distances from the eyepiece. You want to aim for full illumination which is in the middle of the range.

2. Some Common Issues
Dark crescents around the edge of the image – You are either too far away or too close to the eyepiece
Dark spots or areas inside otherwise well illuminated field of view – You phone is more than likely not perpendicular to the eyepiece, so adjust the attitude of the phone relative to the eyepiece.
Colour is off (too warm) – It’s likely the phone is reducing the exposure too much, so try reducing the diaphragm (or power of light) into the microscope. The former will increase the relief of the mineral boundaries making them more defined.
Camera won’t focus – Limitation of your camera phone and/or it’s camera software.

Reducing the diaphragm on the microscope gives better colour reproduction for some camera phones. It also increases the apparent relief of the minerals.

3. Things to do to increase quality
– Particularly when shooting in plain polarised or simple plain light, reducing the diaphragm aperture on the microscope will increase the image quality and colour reproduction.
– Make sure that you get a good light seal on both eyepieces.
– Make sure pin-sharp focus is achieved.
– Better microscopes = better images, better camera phones = better images.

4. Post-processing
If you want to really get the best quality image you can from your phone, I recommend that you take the following post-processing steps. I personally use photoshop, but most image editing packages will achieve the same results.

Step 1 – Adjust the levels. Using the histogram, move the left slider to either: A) to be under the peak of the blacks; or B) to exclude the black peak. Use whichever gives the best result for that image. Then adjust the righthand slider for whites to the left to achieve the desired brightness. You can also adjust the middle slider (contrast) to suit.

The levels for the image before they were adjusted.

Levels for the image after adjustment.

Comparison of the image before and after the levels were adjusted as described.

Step 2 – Apply Sharpening

This may or may not be necessary depending on your image. It’s always worth trying it to see. In photoshop, go to Filters > Sharpen > Unsharp Mask. I applied a strength of 46 % and a radius of 2.1 pixels. This will vary for each image. As a general rule I like to keep the strength slider higher than the radius slider to avoid black halos.

The unsharp mask in Photoshop is a very powerful tool.

It may not seem like your image needs sharpening, but after a unsharp mask is applied the results are stunning.

Step 3 (Optional)

If the colour balance is not completely right you can edit the colour balance manually. Go to Image > Adjustments > Colour Balance (or Cmd + B). This image, however, does not require it.

Final comparison of images. The only thing that has been done is a levels adjustment and sharpening applied.

5. Interconnectivity

Once great way of taking photomicrographs and keeping them together with any observations you may have is to use Evernote. Evernote is a great note taking application for your PC, Mac, Unix Machine, Mobile phone. iPad or tablet. Everything syncs wirelessly over the internet. I can write some notes on my computer about the slide I am looking at, and when I spot something interesting I can open up the Evernote app on my phone and take a photo which gets inserted into my notes. A few seconds later the photo automatically appears in the notes of my computer screen without the need for me to tell it to do anything! Truly a great tool for the geologist!

Evernote is a very useful tool for anyone who takes notes with any kind of media and/or the need to access the notes on a number of different devices.

#8 Britain’s Only Carbonatite


(A brief introfuction to the Loch Borralan Carbonatite)

Between the NE shore of Loch Urigill and Loch Borralan lies Britain’s only carbonatite pluton. The presence of a carbonatite in the Assynt area was first reported to the geological community by Young, Parsons and Threadgould in 1994 . The pluton was actually discovered by an undergraduate from the University of Aberdeen in the late 1980s who was mapping in the area. He puzzled over the rocks and eventually was bold enough to confront his supervisors about it. Sure enough, his speculation was soon corroborated and a fuller investigation was launched.

So what is known about the carbonatite? Well there has been relatively little work conducted on it since it was reported in the Journal of the Geological Society of London in 1994. It was reported that there are 4 varieties that occur:

1. porphyritic white sövite
2. phlogopite sövite
3. sövite breccia
4. foliated silicocarbonatite

The latter of three of the four types above were only observed in situ after part of the pluton was excavated. Since then mineralogical and whole rock analyses were conducted on the four different lithologies. Those chemical analyses revealed that the Loch Borralan carbonatite is chemically and isotopically (carbon) distinct from the surrounding Durness Dolomites in which the pluton is enveloped.

There are many unanswered questions about the pluton. Amazingly, there has been little interest in the body since the mid 1990s. I visited the carbonatite earlier this summer, and collected a sample of the porphyritic sövite. A thin section of this has revealed some interesting minerals which I am in the process of having analysed. Hopefully a report into further findings in the mineralogy of the body will follow some time next year.

A sample of Sövite from the Loch Borralan Carbonatite, showing well equilibrated calcites amongst some other as yet unidentified minerals.