The Geology of Skyrim: An Unexpected Journey

This is a piece I wrote for the European Geosciences Union blog, GeoLog, and can be found on their website

Back in January I did a talk at an event called Science Showoff, a comedy night based in London where scientists stand up in front of an audience in a pub and talk about funny stuff to do with their work. I talked about video games. Not any video game however, I talked about The Elder Scrolls V: Skyrim.

For those of you who don’t know what this is, it’s a fantasy role playing video game. It is a great game with some beautiful graphics, especially the scenery; including flora, fauna and rocks. So I did what any other geologist would do. I mapped Skyrim. This means I used all the internet resources I could to find out the locations of every major ore deposit in the region of Skyrim, colour coded them and placed them on a map. My aim was to find out a possible story for the geological evolution of Skyrim.

Like any scientific investigation, you start off with a theory and you commence your investigations to try to prove it wrong. In some cases it is very difficult to prove the theory wrong and so it remains valid, but in most others you do manage to prove it wrong somehow. However, this does not mean that the time and investigations were wasted; instead this process brings up new answers, and questions that scientists investigate further. In the case of mapping the geology of Skyrim, I came up with an initial theory that I presented at Science Showoff, and have since found that my initial theory was probably wrong. This doesn’t dishearten me though, it has proved an interesting journey – if unexpected – that I am sure has engaged and enthused many people.

First, I will introduce you to my map of all the major ore deposits in Skyrim. I am by no means claiming that this is accurate and I am certainly not claiming that the final interpretation is accurate either (forgetting for a moment we are discussing a fantasy location). My main reason for taking on this little project was to introduce geology to an audience that may not normally engage with the sciences and so the results of this investigation are not meant to be 100% accurate, but they are meant to be inspiring.

My initial map of Skyrim with ore locations indicated as coloured blobs over the coloured topographic map. Red = iron, blue = corundum, purple = orichalcum, white = quicksilver, grey = silver, yellow = moonstone. (Base map modified from one produced by Tim Cook)

My initial map of Skyrim with ore locations indicated as coloured blobs over the coloured topographic map. Red = iron, blue = corundum, purple = orichalcum, white = quicksilver, grey = silver, yellow = moonstone (click for larger). (Base map modified from one produced by Tim Cook)

For a geologist it is not enough to just have a map of where lots of rocks are. What we need is an understanding of the nature of the earth beneath our feet. In finding out how the rocks got where they are today, we can then build up a history of the evolution of the area – including different environments that one area of land went through over millions of years.

The most common types of rocks we find in Skyrim are iron ore and corundum. In this world, corundum isn’t actually a rock – but it is a rock forming mineral. Rocks are simply amalgamations of other minerals in the form of crystals or grains. In igneous and metamorphic rocks, formed from cooling magma or changed through heat and pressure deep in the crust respectively, the minerals are crystalline in form. In sedimentary rocks the minerals are generally granular – from other rocks that have been ground down as sediments into their individual minerals. Corundum most commonly occurs as a mineral in metamorphic rocks, so we are going to assume that our ‘corundum ore’ is a metamorphic rock of some kind.

It is really important to know in what order the rocks got where they are – which is the oldest and which is the youngest. The map above gives us some clues to the order in which the rocks were laid down. Near the top left there is an area of low topography, and inside this is a red blob with a blue blob in the middle of it. The most likely way for these rocks to be in this formation is that the iron (red) is older than the corundum (blue), so the corundum was deposited after the iron ore. Quicksilver is another name for mercury in our world, the most common ore of which is cinnabar. Cinnabar formation is associated with volcanic activity and hot springs. On the map you can generally see quicksilver (white) associated spatially with corundum and iron ore. If you look closely it appears that quicksilver is usually found on the higher topography, so from this it could be inferred that quicksilver was formed later than both the iron ore and corundum.

Towards the bottom left of the province of Skyrim, in the west, you can see a distinct area where there is a quicksilver blob inside an iron ore blob. This would imply that here the quicksilver is directly on top of the iron – but we know that there should be corundum between these two. This is what geologists call an unconformity. An unconformity represents a missing chunk of time in the geological record. When rocks get laid down – by volcanoes or rivers – it takes millions of years. If we are expecting a rock to be somewhere and see that it is missing, we know we are missing a period of geological time in this area and it presents an interesting puzzle: why has this happened? It could be because of tectonic movements of the crust: raising mountains, eroding them then redepositing other sediments on the eroded mountains, but all we see is a road cutting with some different looking rocks and some missing in the middle. This is one of the most important principles in geology, and for many other subjects. It was through identifying an unconformity that James Hutton discovered the concept of ‘deep time’ in 1788 – that the Earth is thousands of millions of years old.

Orichalcum is a bit of an enigma. Many historical texts in the real world refer to orichalcum and yet there is a lot of dispute over what kind of metallic material it was – was it an ore, an alloy or something else entirely? From around 428 BC in Ancient Greek texts began implying that orichalcum was chalcopyrite, a copper ore that can be formed in a number of ways, but always associated with hydrothermal circulation and precipitation in either a sedimentary or volcanic environment. Orichalcum can be seen on the map adjacent to quicksilver on high topography, indicating this may be the most recent rock to be formed in Skyrim’s history.

A cartoon of the four main rocks and the order in which they were laid down (oldest at the bottom). (Credit: Jane Robb)

A cartoon of the four main rocks and the order in which they were laid down (oldest at the bottom). (Credit: Jane Robb)

Iron ore in our world is most commonly derived from banded iron formations. These are at least 2,400 million years old! They represent the point from which organisms started photosynthesising and producing oxygen. As these rocks are so old, many of them have been deformed through metamorphism.

Knowing how individual rock types form doesn’t tell us the whole story about Skyrim’s evolution though. The crust of the Earth is mobile – in some places it pushes together (compresses) and in others it pulls apart (extension or rifting), destroying and forming new crust in those areas respectively like a large conveyor belt around the Earth. When different rocks that should be on top of another (like in the diagram above) can be seen next to each other on the same topographic level, we can infer that some tectonic movement has happened. In the east of Skyrim, we see an area of higher topography and several of the different rocks aligned next to each other.

A topographic base map of Skyrim with my annotations of a compressional fault (line with triangles on it, compressing approximately north-south) and extensional faults (lines with little lines on them). The yellow line A-B is showing the location of a cross section cartoon (below). (Map modified from one produced by Tim Cook)

A topographic base map of Skyrim with my annotations of a compressional fault (line with triangles on it, compressing approximately north-south) and extensional faults (lines with little lines on them). The yellow line A-B is showing the location of a cross section cartoon (below). (Map modified from one produced byTim Cook)

A topographic base map of Skyrim with my annotations of a compressional fault (line with triangles on it, compressing approximately north-south) and extensional faults (lines with little lines on them). The yellow line A-B is showing the location of a cross section cartoon (below). (Map modified from one produced by Tim Cook)

Cross section cartoon A-B of the rocks as they might be underground, showing extensional faulting and erosion. The black ‘ticks’ on the diagram indicate the direction of movement of the land relative to the areas around it. (Credit: Jane Robb)

Skyrim is surrounded to the south and west by mountains, the largest being the Throat of the World. Mountains usually form through landmasses compressing together and bunching up. As this happens the rocks around the area of compression undergo an intense amount of pressure and heat that changes the rocks from their original state – forming metamorphosed rocks. Two of our most abundant rock types are metamorphic – iron ore and corundum. These rocks are also the oldest we see in Skyrim, indicating that for the first part of Skyrim’s history (spanning at least 2 billion years) it was under the sea forming iron ore sediments. A rock, we cannot be sure what it was originally, was deposited on top of the iron ore several millions of years later and then both were squeezed and pushed into mountains and the rest of Skyrim.

Millions of years later, the land started to pull itself apart in the east of Skyrim. Extension is a common trigger for volcanic activity, and combined with what could either have been a warm and wet or marine environment quicksilver and orichalcum deposits began to form above the previously metamorphosed rocks.

In modern day Skyrim, we still see some hot springs and nearby volcanic activity in Solstheim as well as the east being aptly named The Rift.

Showing Off About Science

On the 3rd April 2012 I did a set at Science Showoff held every month at the Wilmington Arms in London. There are 10 acts who each have 9 minutes to talk about ANY aspect of science using any technique they want – it can be music, practical demonstrations or simple Powerpoints (there have been rock guitarists singing about physics, opera singers chatting about STD’s…the lot!). I was kindly asked by the organiser to do a set on geology, as it was a science they had not yet had on stage. It ended up going down pretty well on the night, so I thought I would put the presentation and my spiel up on my blog. The pictures were all originally Powerpoints that I designed so some might not work quite so well in a blog but nevertheless – enjoy!

I am a geologist. I know what you are thinking.

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No, seriously. I love geology, I have done it since I was a wee girl and I have to say I have had some of my fondest near death experiences, along with the odd moment when health and safety would have a heart attack.

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(It was a disused asbestos quarry for your information). And of course those odd moments where I got so depressed at being on my own, on a hill, trying to dry my socks in what can only be called rubbish weather and looking at rocks. So, I might have defaced some geological heritage (!).

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Apart from all that, we did do some proper geology though. Here’s a little story of one rock that caught my attention during my dissertation…

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Initially I can tell that there are two different rocks here, one on top and one on the bottom. I can also say that one is likely to be more silica rich than the other due to the colour – the lighter one will likely contain minerals such as quartz (SiO2) and feldspar (Na, Ca), and the darker one will be more likely to contain olivine ((Fe,Mg)2SiO4) and pyroxene XY(Si,Al)2O6. This tells me about the way in which they crystallised and from where. The dark rock is likely to be primitive, from melting of mantle and very quickly cooled to rock. The lighter one probably spent a little more time in a magma chamber, meaning there are more evolved chemical species comprising the rock.

The size of the crystals making up the rock also tells me something about it: the groundmass is very fine in both of them, but especially so next to the boundary of the two. Both rocks also contain much larger crystals (up to 1cm large). This means that both rocks spent very little time in a magma chamber, but both did have enough time to grow some large crystals. This ties in nicely with the chemical observation, because the lighter rock has comparatively more large crystals than the dark rock, indicating more time for the crystals to grow large in a chamber. These facts also indicate that these rocks were likely to be extruded as a lava flow rather than intruded as a dyke.

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The dark rock contains olivine and augite as very small crystals and plagioclase (Na, Ca) feldspar as much larger ones. From these simple mineral associations I can confirm this is a basalt. The lighter rock contains quartz, a mix of Na and K feldspar, and magnetite telling me it is a rhyolite. This basically means that the rocks contained various silicates: magnesium, iron, aluminium, calcium, sodium and potassium. Both of the classifications fit in really well with my preliminary thoughts.

What is confusing is that rhyolite is formed from evolution of basalt magma – through the relative enrichment of the magma in silica with continued crystallisation giving them different mineral associations, basalt with Al, Mg, Fe and Ca and rhyolite with Si, Na and K – so how can they be cooled as melt together at the same time?

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The answer could be in the quartz crystals. These crystals have an unusual appearance indicating that they could have been resorbed into the melt at some point during their evolution. This could happen if the crystals were unstable in the new melt chemistry – for example if a basalt was intruded into an evolved silicic rhyolite melt, the laws of thermodynamics would tell you that the silica would be assimilated into the melt fraction that was undersaturated in silica.

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So somehow we have a magma chamber, likely formed from shallow large scale melting of the crust to produce a basaltic magma that began to evolve. Then, at some point in its evolution, there was possible ingress of another wave of basaltic magma via some sort of intrusion. This is common at ocean ridge systems – but how can we decide whether or not this is magma originating from an ocean ridge tectonic setting?

This is where the Rare Earth Elements come in.

Geologists wanted to know what distinguished these rocks from each other, not purely based on their simple chemical compositions which can be similar from more than one setting but also on their trace element compositions. Could these give a more definitive answer as to the tectonic provenance of the rock?

It turned out the answer was yes. And it was beautifully logical. At subduction zones, it was possible to see trace amounts of LILE elements in the basalts. This is important because most LILE elements are soluble, so that it proves there is incorporation of seawater into the mantle during subduction. Similar principles apply for all kinds of rocks – whether they are from island arcs, mid ocean ridges, continental mountain chains or those other random islands in the middle of the sea no one really knows what they are!

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So what is our rock then? Firstly, I did not actually do any X-Ray Fluorescence on it to find out, but the likely story is that they were from a magma chamber formed through stretching of the crust – similar to ocean ridge magma formation. The timing of the eruption of these lavas was concurrent with the opening of the North Atlantic, that caused widespread stretching of the crust, along with the emergence of the Iceland plume which may have caused the extent of volcanism seen across the Hebrides.