Archive | Earth Magnetism & Rock Physics RSS feed for this section

Imaggeo on Mondays: A rolling stone gathers no moss

31 Mar

Philippe Leloup brings us this week’s Imaggeo on Mondays, with tales from a mountain trail that show a geologist can never resist a good rock!

In reality, this shiny slab of rock is about 20 centimetres across. Polished to perfection, the layers of marble and amphibole are beautiful to behold. (Credit: Philippe Leloup via

In reality, this shiny slab of rock is about 20 centimetres across. Polished to perfection, the layers of marble and amphibole are beautiful to behold. (Credit: Philippe Leloup via

This image is that of a polished slab of a rock composed of interlayered marbles and amphibolites. The sample was once part of a small dry-stone wall bordering an outdoor kitchen along a trail along the Ailao Mountain Range in China (or Ailao Shan in Chinese).

As I passed by, a small black eye looked at me, and I couldn’t resist asking the owner to give me that stone – one that could easily be replaced by any other rock nearby, and he kindly agreed. The rock was special for me because I felt that its structure would be spectacular.

The Ailao Range is part of the Ailao Shan – Red River shear zone, a region that stretches for more than 1000 kilometres – from southeast Tibet to the Tonkin Gulf. During the Oligo-Miocene, the Indochina bock (encompassing Vietnam, Cambodia, Laos and Thailand) was pushed away from the collision between the Indian and Asian continents and moved several hundreds of kilometres towards the southeast along that ~10 kilometre-wide shear zone. Today, evidence that intense ductile deformation occurred are found in gneiss and marbles showing steep foliation, horizontal lineation, and numerous left-lateral shear features – a type of deformation that leaves rocks looking like this:

 A thin section microphotograph (total width ~0.5 mm) showing several feldspar crystals with bended tails. These tails show that they have slowly rotated counter-clockwise. These rolling structures are characteristic of left-lateral ductile deformation. (Credit: Philippe Leloup via

A thin section microphotograph (the total width is about 0.5 mm) showing several feldspar crystals with bended tails. These tails show that they have slowly rotated counter-clockwise. These rolling structures are characteristic of left-lateral ductile deformation. (Credit: Philippe Leloup via

When I cut the rock it turned out that the amphibole layer had a very special shape, like a Swiss roll, resulting from simple shear – something that revealed spectacular colours and a stunning shape when seen in section.

By Philippe Leloup, University of Lyon

Imaggeo is the EGU’s open access geosciences image repository. Photos uploaded to Imaggeo can be used by scientists, the press and the public provided the original author is credited. Photographers also retain full rights of use, as Imaggeo images are licensed and distributed by the EGU under a Creative Commons licence. You can submit your photos here.

Geoscience under the tree

18 Dec

In a festive-themed post, EGU Media and Communications Manager Bárbara Ferreira selects a plethora of geoscience-inspired Christmas presents, which you could give to your favourite researcher. Please note that, with the exception of the last one, the items listed below are not necessarily recommended or endorsed by the EGU.

For me Christmas is more about eating large amounts of food and celebrating with family and friends than it is about giving and receiving presents. But I am guessing many of the readers of this blog are still scratching their heads thinking what gifts to get to the geoscientists in their families, to their Earth or space science researcher friends or, why not, themselves. This, and the fact that Paleoseismicity posted about some beautiful geology shoes a few days ago, is why I’ve set out to discover the best geoscience-inspired gift items out there.

Compiling this list ended up being easier than I thought because a few people, such as Georneys’ Evelyn Mervine and Agile’s Matt Hall have written similar blog posts in the past. And also because I discovered that Etsy – the e-commerce website for all things handmade or vintage – has an impressive collection of geoscience-y items. So, brace yourselves for a link-rich post!

Solid Earth

I’ll start with a present idea for our crafty readers: if you are into knitting, or know someone who is, this book filled with knitted-dinosaur patterns might be for you. If you’re not crafty, you may prefer to gift this triceratops cup or a pair of agate bookends, or even this t-shirt with a different take on the Earth’s internal structure. The geomorphologist in your life might like this antique map illustrating the geomorphology of the Alpine region or this simple yet beautiful travel journal.

If, instead, volcanology is your thing, then you might like this awesome volcano woolly hat – and if you are looking for a gift for a little one, this wooden volcano stacker could be your choice. For soil scientists, Etsy has a collection of beautifully illustrated soil postcards, while tectonic scientists and seismologists, may find this t-shirt funny. This science kit would suit a young fan of rocks and minerals, while this tie with crystalline formations would be more appropriate for a grown up.

Volcano hat by MariaBjork

Volcano hat by MariaBjork

Soft Earth

Moving on to soft-Earth disciplines, atmospheric scientists might like this wonderful screen print of different types of clouds, or this original necklace representing the various layers of the Earth’s atmosphere. And there’s this rather neat calendar of the sky and sea, which may also please ocean scientists. These researchers might also like an ocean tide ceramic pot or a 19th century map of the Atlantic Ocean.

Budding hydrologists, on the other hand, may be fascinated by this hydropower kit, while older ones will likely appreciate this antique engraving of water engineering. On the topic of antiques, the climate scientist in your life may like this climate map of Europe or this beautifully illustrated book to teach kids about climate. When gifting biogeoscientists, you can’t go wrong with this fantastic diatoms t-shirt (available for men and women) or these seaweed magnets.

Diatoms t-shirt by vortextradingcompany

Diatoms t-shirt by vortextradingcompany

Space and planetary science

Moving up into the upper atmosphere, your favourite solar-terrestrial scientist might like to receive this rather cute card of aurora in the Arctic or, for something a bit different, this pair of Northern Lights leggings! Going further up into space, the Earth’s magnetosphere finds its way into this totebag/backpack while the solar corona is the star of this antique print.

Planetary scientists also have plenty to choose from, with a variety of art decals and solar system charts available on Etsy. There is even a seller who builds jewellery with photos from NASA missions, such as this Mars Curiosity Rover pendant. Budding space and planetary scientists will likely be happy with this space exploration kit from National Geographic.

Interdisciplinary areas

Moving on to the more interdisciplinary areas of the EGU, I couldn’t help but mention Slow Factory, who produce stunning (but expensive!) clothing items from satellite images: the Terra MODIS Greenland dress and this silk square with an image of phytoplankton from the Bay of Biscay are two of the highlights. For something a bit more affordable, you could gift this top to bottom poster from Our Amazing Planet (sadly, the original interactive infographic can’t be put up on the wall) or this carbon cycle t-shirt. If you are feeling crafty, you can get LEGOs to build this rather incredible LEGO globe. Energy, resources and the environment enthusiasts have plenty to choose from, from a sustainable Earth lab or a solar-powered night light to a pair of windmill earings or a wind-energy decal. If great waves are more your thing, you may be interested in this tsunami top or, if landslides are your natural-hazard of choice, in this interesting pendant.

If you, like me, prefer to give and receive an experience as a gift, then why not offer a geoscientific trip? Though I haven’t been on a trip of this kind myself, I found a few companies that organise geo-themed excursions, such as this one in Italy, this one in Iceland or this one for trips further afield.

Finally, I couldn’t finish this blog post without suggesting the best present of them all (OK, I’m biased!). This Christmas, why not gift EGU memberships to the Earth, planetary and space scientists in your life? It is very affordable and researchers will likely appreciate the discounted registration rate members receive to the EGU General Assembly!

By Bárbara Ferreira, EGU Media and Communications Manager

The Geology of Skyrim: An unexpected journey

15 Nov

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 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 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.

By Jane Robb, EGU Educational Fellow


Geotalk: Dr Olivier Galland

12 Dec

Geotalk, featuring short interviews with geoscientists about their research, continues this month with a Q&A with Dr Olivier Galland (University of Oslo), who tells us about his volcanology research and the importance of outreach in promoting the Earth sciences. If you’d like to suggest a scientist for an interview, please contact Bárbara Ferreira.

Olivier Galland at the foot of the Tromen Volcano, northern Patagonian Andes, Argentina, during a field expedition of Nov-Dec 2011. Photograph: Derya Gürer

First, could you introduce yourself and let us know a bit about your research topic(s)?

Becoming a volcanologist was my childhood dream, and my studies have always been oriented towards this goal. I first integrated the École Normale Supérieure in Lyon, then I completed my MSc and PhD degrees at the University of Rennes 1. I continued with a postdoc at the Norwegian Centre of Excellence for Physics of Geological Processes, University of Oslo, where I have become Senior Researcher.

My main research topics focus on the mechanics of fluid-rock systems and their implications on volcanic processes. In other words, what is the mechanical behavior of a system where a fluid of given properties flows into a deforming solid matrix? Such a system cannot be understood only from the point of view of the fluid or of the solid, but by the dynamic mechanical interplay between them. This fundamental mechanical loop controls numerous geological processes such as, among others, magma transport and emplacement in the Earth’s crust, hydraulic fracturing, and explosive volcanism. I have mostly addressed these processes through integration of field observations in volcanic systems and quantitative laboratory experiments.

Last year, you received an EGU Arne Richter Award for Outstanding Young Scientists for your “remarkable contribution to the understanding of volcanic and magma emplacement processes”. Could you summarize the research you have done in this area?

Magma transport plays a key role in the Earth’s dynamics, as it accounts for the main mass and heat transport through the crust. Although magmatism has been studied for more than a century, major questions have remained unsolved. For instance, geologists have assumed that volcanism can occur only in extensional tectonic settings, the extension providing space for magma pathways. This generally accepted assumption is contradictory with the occurrence of intense volcanic activity in the Andean Cordillera, where tectonic shortening has been coeval with volcanism. Part of my research work has demonstrated that volcanism can take place in compressional tectonic settings by focusing on a spectacular case study: the Tromen volcano, in the northern Patagonian Andes. Through several field campaigns at Tromen, we collected structural and geochronological evidence, which showed that the volcano built up during the regional tectonic shortening. To explain how magma can rise in such setting, I also designed a novel experimental apparatus that can simulate coeval tectonic deformation and the injection of low viscosity magma. The experimental results show that magma can migrate along thrust faults, strongly modifying our understanding of magma plumbing systems in active margins and volcanic arcs.

In 2008 you embarked on an exciting scientific expedition called the Andean Geotrail: “cycling 10,000 kilometers to discover the Earth and its resources”. Could you tell us about this adventure, including its aims and what you learnt from it?

The Andean Geotrail was a personal outreach project organized together with my partner, Caroline Sassier, also a geologist at the University of Oslo. The project was based on a 9-month cycling adventure in a spectacular geological environment: the Andean Cordillera. The aim was to use the adventure as a pedagogical tool to catch the attention of the young public and to trigger their curiosity through our own observations. This made Earth sciences less theoretical and more dynamic, and our hope was to create scientific vocations by sharing our scientific knowledge through a unique personal experience. Seventeen schools in France and Norway were associated, involving almost 600 pupils from 6 to 18 years of age.

During the expedition, we cycled from Ushuaia, southernmost Argentina, to Cuzco, Peru, and after the theft of our bikes, we walked to Nazca for a last 400 km long crossing of the Andes. We selected and visited more than 30 geological localities along the route to illustrate various implications of Earth sciences in our society (natural resources, natural hazards, geological landscapes). During the visits, we made our own observations and interviewed local geologists or workers. Since our return, we have presented the expedition in the involved schools and during public conferences, and produced an exhibition of our photographs.

By visiting the selected localities we obviously learnt a lot about the applications of Earth sciences in modern society. But overall, we gained an incredible human experience through the numerous encounters with the Andean populations.

You are also a keen photographer, and you were even one of the finalists of the 2012 EGU Photo Competition. How can Earth science photography contribute to promote the importance of geoscientific research among the wider public?

The most difficult challenge to attract the young generations is to overcome their initial reluctance to Earth sciences by catching their attention and triggering their curiosity about the Earth system. Our experience with the pupils during the Andean Geotrail clearly showed that it is a very challenging task without relevant support. During our conferences in the schools, the only way we managed to create a successful link with the pupils was to show them fantastic photographs of spectacular, unusual, strange and/or extreme geological patterns. Once this link has been established with the pupils, very interesting discussions started and it became possible to share our scientific knowledge with them.

Photography also has the potential to associate two communities that often barely interact: scientists and artists. In addition to be a fascinating scientific subject, the Earth and geological patterns are also unlimited sources of inspiration for artists and lovers of natural beauty. Photography of geological patterns is thus a precious way to promote geoscientific research and its associated challenges via artistic contemplation of the esthetic nature of the Earth.

Last but not least, what are your future research plans?

In the near future, I aim to expand my current work. I am leading a field-based project in the northern Patagonian Andes to unravel the structure of exhumed sub-volcanic systems emplaced in relation to thrust faults and folds, to better constrain the processes of magma transport in compressional tectonic settings. This is a good complement of the former project on Tromen volcano.

In addition, I aim to establish a quantitative bridge between volcano geophysics and laboratory models of volcanic processes. I am adapting my experimental apparatus to study the subtle ground deformation induced by the emplacement of magmatic dykes. Combined with new theoretical models, the provisional experimental results are expected to considerably help geophysicists to interpret ground deformation data monitored in active volcanoes with GPS and interferometry Radar (InSAR). In particular, this technique has the potential to provide a new tool to predict the location of forthcoming volcanic eruptions.

The Andean Geotrail project. Caroline Sassier lost in the immensity of the Bolivian Altiplano (4000 MOSL). Photograph: Olivier Galland



Get every new post on this blog delivered to your Inbox.

Join other followers: