Imaggeo on Mondays: Dragon Blood Tree

Imaggeo on Mondays: Dragon Blood Tree

On a small and isolated island in the Indian Ocean you’ll find an endemic population of Dragon Blood Trees (Dracaena cinnabari). Burly, with an interesting umbrella-shaped fractal canopy, these unique trees are a sight to behold.

To see them for yourself, you’ll have to travel to the little known Socotra archipelago. Off the coast of Somalia, but belonging to Yemen, the group of islands boast an impressive assortment of endemic plant life, making them know as the ‘Galapagos of the Middle East’.

Crucial to the uniqueness of the flora and fauna of the archipelago is Socotra’s geographical position and how it came to be there. The African plate extends out from the Horn of Africa, east of the Guardafui graben, in what is known as the Socotra Platform. Here you’ll find four islands, of which Socotra is the largest, as well as two scars of former islands which have been eroded away by wave action.

At in excess of 240 kilometres east of the Horn of Africa and 380 kilometres south of the Arabian Peninsula there is no getting away from the remoteness of the archipelago. Testament to this is the presence of seven endemic bird species on the island.

So how did the strange looking Dragon Blood Tress and other flora and fauna come to populate Socotra and its neighbours?

It is thought that until 43 million years ago, the Socotra archipelago remained largely submerged. Although there were some brief emergence events during the Jurassic/Cretaceous and Cretaceous/Tertiary, given the area was re-submerged after this time, they are considered of little importance.

Subsequently, Socotra Island continued to grow due to uplift. Despite changing sea depths, there are indications that land species could migrate over from mainland African and Arabia via land bridges and stepping stones. With ‘cousin’ species present in Somalia and Arabia, it’s likely the Dragon Blood Trees originated there in the distant past.

From 16,000 years ago onwards, the isolation of the archipelago grew due to a combination of further flooding of low-lying areas, the formation of large basins (namely the Guardafui and Brothers basin) and increasing distance from the mainland. Since then, the species on Socotra and its neighbouring islands have had time to evolve and adapt to their surroundings, become different, albeit sometimes closely related, to their continental counterparts.

It was only around the third century BC that Socotra started to emerge from its isolation after attracting the attention of the young Alexander the Great during one of his war campaigns. The island then became known in the Hellenic World and all the Mediterranean for being one of the main sources of incense, myrrh and dragon’s blood powder resin.

As Socotra commercial importance gradually faded away in the centuries to follow, Dragon’s Blood resin remained one of the main exports of the island. The resin was considered a precious ingredient of dyes, lacquers and varnishes, and the legend has it that Antonio Stradivari – the famous seventeenth century luthier from Cremona – used Socotra’s red resin to varnish his violins.


The landscape of the Socotra archipelago. Credit: Annalisa Molini via Flickr.

One thing is for sure, as Annalisa Molini’s (Assistant Professor at the Institute Center for Water and Environment, in Abu Dhabi), photographs attest to: Socotra island and it’s Dragon Blood Trees are stunning.

However, the remoteness of the Socotra archipelago and the current armed conflict in Yemen threaten to put at risk the island’s important and unique natural heritage; one that no doubt, should be protected and preserved.


M. Culek: Geological and morphological evolution of the Socotra Archipelago (Yemen) from the biogeographical view, Journal of Landscape Ecology, 6, 3, 84–108, DOI: 10.2478/jlecol-2014-0005, 2014

Brown, B.A. Mies, Vegetation Ecology of Socotra, Springer Netherlands, Dordrecht, 2012. doi:10.1007/978-94-007-4141-6.

Imaggeo is the EGU’s online open access geosciences image repository. All geoscientists (and others) can submit their photographs and videos to this repository and, since it is open access, these images can be used for free by scientists for their presentations or publications, by educators and the general public, and some images can even be used freely for commercial purposes. Photographers also retain full rights of use, as Imaggeo images are licensed and distributed by the EGU under a Creative Commons licence. Submit your photos at

GeoTalk: Wouter Berghuijs, Union Level Early Career Scientist Representative

GeoTalk: Wouter Berghuijs, Union Level Early Career Scientist Representative

The EGU offers a platform for early career scientists (ECS) to become involved in interdisciplinary research in the Earth, planetary and space sciences, through sessions, social events and short courses at the annual General Assembly in April. One of the ways of ensuring that the voice of the Union’s ECS membership is heard is via the division early career scientist representatives.

Feedback gathered by the division representatives is collected by the Union level representative, who takes it to the EGU’s Programme Committee (PC) – the group responsible for organising the EGU’s annual General Assembly and the EGU Council – which is in charge of the overall management of the Union.  At the 2015 General Assembly (GA), Wouter Berghuijs, took on the role of union level Early Career Scientist Representative; a post he will hold until April 2016. In this instalment of GeoTalk, Wouter will tell us more about the ECS membership and how he hopes to make a difference to the community during his one-year term.

Before we get stuck in, could you introduce yourself and tell us a little more about yourself and your career?

My name is Wouter Berghuijs. I am a PhD student in Hydrology at the University of Bristol (UK). Prior to moving to Bristol, I gained an MSc and BSc in Civil Engineering at Delft University of Technology (The Netherlands). During my MSc, I spent three months at the University of Illinois at Urbana-Champaign (USA) for a research stay, and a further three months at the University of Bristol. I have been involved with the EGU since 2013, first as the Young Scientist Representative for the Hydrology Division, and since the GA in 2015 as the Union-wide Early Career Scientist Representative (editors note – Council approved having the newly elected representative to have a Union-wide role, rather than just represent the ECS membership at the Programme Committee level).

In my day-to-day research I am interested in what factors drive hydrological differences between places. Instead of studying one place in detail, I compare several hundred catchments (surface area that drains rainfall into a river, lake or reservoir) located in different landscapes and climatic regions. The aspects of hydrologic behaviour I look at can range from floods to droughts, and from short-term dynamics to multi-decadal averages. With a large part of hydrological science consisting of case-studies at individual locations, findings are difficult to transfers to other places. The comparative approach brings in opportunities to develop generalisations and expose patterns that would not be observed when a single catchment is studied in isolation.

For those readers who might not be so familiar with the Union’s ECS membership, could you explain the main idea behind it and your role as Union Level Early Career Scientist Representative?

Approximately one quarter of the Unions’ membership consists of scientists in the early stages of their career. EGU wants to provide support to this group, which has different needs compared to more established scientists. Therefore EGU supports these members by providing reduced conference fees, recognising outstanding students, awarding travel grants, organising short-courses, arranging networking possibilities and more.

Instead of going for a top-down (senior members decide all) approach, EGU decided to appoint Early Career Scientists Representatives for all their scientific divisions. These representatives serve as the link between the ECS members and the board of the different divisions. It is their task to ensure ECS needs are met, both at the Assembly and throughout the year. Other ECS members with questions, comments and thoughts can get in touch with them to ensure their opinion is represented within their division.

In my position of Union level Early Career Scientist Representative, I gather information from each of the division representatives and bring it to the EGU’s Programme Committee – the group responsible for organising the EGU’s annual General Assembly, and the Union’s Council – the board responsible for the overall management and control of the Union.

Some of the ECS Representatives at the most recent General Assembly in Vienna. From left to right, top to bottom: Matthew Agius (SM), Shaun Harrigan (HS),

Some of the ECS Representatives at the 2014 General Assembly in Vienna. Top, from left to right, (in brackets, the Division they represent) : Matthew Agius (SM), Shaun Harrigan (HS), Wouter Berghuijs (ECS Representative), Roelof Rietbroek (G), Matthias Vanmaercke (SSS), Auguste Gires (NP), Nanna B. Karlsson (CR), Bottom (left to right): Ina Plesa (GD), Lena Noack (PS and Deputy Union Level ECS PC Representative), Sam Illingworth (ECS PC Representative , 2013- 2015), Guilhem Douillet (SSP), Anne Pluymakers (TS), Jone Peter (stand-in for Beate Krøvel Humberset, ST).

Why do you feel passionately about the ECS community?

The nice part of working for the ECS community is that relatively small contributions can make huge difference to people’s research career. For example, the ability to attend a conference due to an awarded travel grant can be really important to meet other people in your field and create exposure for your research. It sounds somewhat cliché, but the ECS members are the future of geoscience. An investment now in one of these members can be important for the next 40 years.

Additionally, with the recent appointment of ECS representatives it is an interesting task to start shaping how these representatives can best contribute to the Union, and can make sure they voice the opinion of a broad group of ECS members. With a significant part of the members being ECS it is a nice challenge to change this group from being mostly consumers of activities, to explicitly having them contributing at an organisation level.

What is your vision for the EGU ECS community and how do you hope to drive change during your year long position?

Sam Illingworth (on the left) handing over the batton of the ECS Community over to Wouter at EGU 2014. Image Credit: Roelof Rietbroek, ECS Representative for the EGU Geodesy Division.

Sam Illingworth (on the left) handing over the batton of the ECS Community over to Wouter at the EGU General Assembly, 2014. Image Credit: Roelof Rietbroek, ECS Representative for the EGU Geodesy Division.

Last year Sam Illingworth was the PC Early Career Scientist Representative and made a great start to bringing all ECS together and voice their opinion to Council. My first task is to continue this work. The relative short appointment (1-year) makes it difficult to ensure both short-term and long-term improvements to the Union are made. Short-term improvements involve, for example, dealing with the feedback that provided suggestion for improvement of next years’s GA. During the year I have regular Skype meetings with all ECS representatives, and it is then my task to make sure the outcomes are discussed during e.g. the programme committee meeting (where the plans for the upcoming GA are usually set out), and council meeting later this year.

Recently, the name used to refer to early researchers across EGU was changed from Young Scientist to Early Career Scientists. Could you tell us a little more about what brought about that change and its significance?

One of the findings of the 2014 Young Scientist Survey and Forum at the GA was that early career scientist did not identify with the term young scientists due to the age connotations associated with the name. ECS benefits were considered important during the onset of academic career, independent of the age of the person. The ECS Representatives put together a proposal promoting for the name change which was brought to the EGU Council; who voted in favour of the renaming. It highlights the bottom-up nature of the organisation and how early stage scientists can make a difference in the Union.

The past General Assembly, saw a record number of short courses take place and the growth of networking opportunities and ECS specific activities. What further changes can the ECS look forward to for the 2016 conference?

The young scientists' lounge at EGU 2014. Credit: Stephanie McClellan/EGU

The young scientists’ lounge at EGU 2014. Credit: Stephanie McClellan/EGU

The short courses and ECS specific activities have been very popular at this year’s EGU, and they are definitely a keeper. I don’t think these activities should increase in number, as it is not the intention to lure away the ECS from the regular parts of the scientific meeting; it is important that they also integrated as best as possible with the more established members of their divisions.

The goal for next year is mostly to maintain the activities that were a success, try a few new concepts for those sessions that didn’t work so well. There are also several improvements that can be made such as the capacity of the rooms of short courses and their timing compared to the rest of the programme.

How can those wanting to, get involved with the EGU?

EGU is a versatile organisation; besides organising their Annual General Assembly and running 17 peer-reviewed open access journals, EGU is busy with Topical meetings, education, and various forms of outreach. Because all these aspects are run by members there is always need for motivated people with refreshing ideas. If the ideas you have (or you want to develop) relate to your division, you should contact the respective ECS representative. If the ideas are broader ranging than your division, a good start is to contact me as the Union Level ECS representative.

You can also check the EGU volunteering pages, where you’ll find information on the helping out the EGU in their activities year round. Additionally, the EGU Blogs, from the EGU offical blog GeoLog, through to the Network and Division Blogs, welcome guest contributions; so if you’d like to report from an Earth science event, conference or fieldwork, or comment on the latest geoscientific developments and write about recently published findings in peer-reviewed journals you might consider sharing your thoughts on the Blogs. For more information or to submit a post, click here or get in touch with the EGU Communications Officer, Laura Roberts Artal.

Geosciences Column: What made the comet sing?

Geosciences Column: What made the comet sing?

Late last year the Rosetta’s Plasma Consortium (RPC) announced that Comet 67P/Churyumov-Gerasimenko, which the European Space Agency’s Rosetta spacecraft has been studying since August 2014, was singing into space. Now, in a paper published today in the EGU’s open access journal Annales Geophysicae, the RPC team reveals more details about 67P’s song, including why the comet was singing.

The sounds ‘emitted’ by 67P are oscillations in the magnetic field around the comet. Its space environment is permeated by the solar wind – a continuous stream of electrically charged gas (called plasma) and magnetic field lines stringed along from the Sun – which interacts with the comet’s gas-dust atmosphere. A consequence of this interaction is an ‘induced cometary magnetosphere’. In other words, even though the nucleus of 67P has no magnetic field of its own (as announced at this year’s EGU General Assembly), the comet’s atmosphere or coma is magnetised.

As reported in Annales Geophysicae, the RCP magnetometer on board Rosetta started to detect large-amplitude fluctuations in this magnetic field on arrival of the spacecraft at the comet on 6 August 2014. For four months, until November 2014, the RPC team detected about 3000 cases of wave activity with frequencies of about 40 millihertz.

“This is exciting because it is completely new to us. We did not expect this and we are still working to understand the physics of what is happening,” said RPC principal investigator Karl-Heinz Glassmeier at the time ESA reported the discovery of the ‘singing comet’ waves on the Rosetta blog. Glassmeier is head of Space Physics and Space Sensorics at the Technische Universität Braunschweig, Germany, and the senior author of the Annales Geophysicae paper.

This observation took the team somewhat by surprise because it is the first detection of waves of this nature at a comet. In previous cometary encounters, such as the International Cometary Explorer and Sakigake spacecraft flybys of comets Giacobini-Zinner and Halley, researchers measured wave activity with frequencies some 10 times lower.

The difference in the 67P case is that, as Rosetta travelled alongside the comet, the instruments could measure the magnetic field for a long time, and while the comet was still relatively far away from the Sun. The RPC instruments collected the data reported in the new study while the comet was between 400 to 540 million kilometres away from the Sun. At this point, the comet’s activity was low: it was not expelling a lot of gas and dust into space, and the ‘induced magnetosphere’ was just beginning to form.

Since the song 67P sings at this early stage is very different from the ‘classical sounds’ detected at comets closer to the Sun, the team concluded a new mechanism must generate the 40 millihertz waves. (If you are interested in finding out more about the difference between the two types of cometary sounds, and the processes that generate them, read the extra information at the end of this post.)

When RPC scientists first uncovered 67P’s mysterious song, they suspected it had something to do with the comet’s activity – even if low – and the neutral particles it releases into space. Ultraviolet radiation from the Sun causes ionisation of these atoms and molecules, including water molecules. In the plasma environment around the comet’s nucleus, the newborn ions move perpendicularly to the magnetic field, forming what is called a cross-field electric current. It turns out that this current is unstable, and ultimately, it is what makes the comet sing.

Schematic of the processes that generate the singing comet waves. Credit: Karl-Heinz Glassmeier (comet inset credit: ESA/Rosetta)

Schematic of the processes that generate the singing comet waves. Credit: Karl-Heinz Glassmeier (comet inset credit: ESA/Rosetta)

“The physical process is somewhat difficult to understand without a deeper understanding of plasma physics, but we can use a simple analogy to have a better idea of what’s going on,” says Glassmeier. “Consider your garden hose. If you start the water flow, there is a chance that the hose starts to oscillate, generating waves. This is about what happens in the plasma. Of course, the flow we have in the cometary situation is not like water, but is a flow of charged particles. But somehow the analogy is suitable.”

The questions left to answer are whether 67P continues to sing the same song as it gets closer to the Sun, and whether it starts emitting more classical cometary sounds.

Glassmeier says RPC instruments detected the 40 millihertz waves at least until February this year, when Rosetta was about 350 million kilometres away from the Sun. “Around this time, the activity is changing, other features show up, the plasma interaction region becomes much more violent. Singing comet waves are still present, but buried under a variety of other features we are currently trying to understand.”

“Whether we also observe the classical type of cometary waves, like those observed at Halley, is very difficult to judge. We are heavily working on further analysing the dynamics of this region to find out more.”

 By Bárbara Ferreira, EGU Media and Communications Manager



Extra: A more detailed explanation of the difference between classical cometary waves and the ‘singing comet’ waves, by Karl-Heinz Glassmeier:

Plasma waves play a most important role in coupling newborn ions of cometary origin with the solar wind plasma. As the particle density of the solar wind is rather small, the interplanetary space is almost a vacuum. There are no collisions between solar wind particles and the cometary ions causing the required coupling. Without such a coupling the cometary ions would move relative to and undisturbed by the solar wind. However, if the comet-solar wind interaction region is much larger than a typical gyro-radius of a cometary ion, as in the case of comet Halley, cometary ions constitute so-called ring-beam distributions in the phase space of the solar wind plasma. Such distributions are heavily unstable and produce the classical cometary waves as observed at Halley and Giacobini-Zinner. These waves, on the other hand, are able to scatter cometary ions as the electric field fluctuations of the waves impact the ion motion. In this way the plasma waves couple the solar wind particles and the cometary ions. The waves act as a kind of mediator between solar wind and cometary ions. A more detailed treatment shows that the frequency of the waves as observed in the spacecraft frame of reference is very close to the local gyrofrequency of the cometary ions. [Editor’s note: Recall that, in the presence of a uniform magnetic field, an electrically charged particle moves in a circular motion; the radius of this circle is the gyro or Larmor radius, and the angular frequency is called gyrofrequency.]

The situation we observed at Chury in the first months after the arrival at the comet is rather different. The interaction region is rather small because of the weak activity of the nucleus. Actually, the size of the interaction region is much less than the gyro-radius of a cometary ion.

I like to call this region the Larmor sphere of the comet. Within the Larmor sphere the newborn ions have not yet been able to perform a complete gyro motion around the solar wind magnetic field. The newborn ions just constitute an electric current perpendicular to both the solar wind flow and magnetic field. This cross-field current is much different from any ring-beam phase space situation observed in case of the large interaction region of Halley or Giacobini-Zinner. In our model, the cross-field current constitutes the very first effect the newborn ions impose onto the ambient plasma. Only later, the newborn ions develop into ring-beam type particle distributions. But in these later stages the plasma volume with the new-born ions have already passed the nucleus, moving downstream.

It is this fundamental difference between the fully developed ring-beam situation at strongly outgassing comets and the cross-field current situation at weakly active comets. In the former case the unstable phase space distribution is moving with the solar wind plasma, while in the latter case the cross-field current is almost fixed with respect to the nucleus.

Imaggeo on Mondays: Velociraptor in the Zagros Mountains

A velociraptor in the Zagros fold and thrust belt. Credit: Stephane Dominguez (distributed via

A velociraptor in the Zagros fold and thrust belt. Credit: Stephane Dominguez (distributed via

How many times have you turned your head up to the sky and spotted familiar shapes in the clouds? Viewing structures from afar can reveal interesting, common and, sometimes, funny patterns.

Satellite images are often used to map geological terrains. They offer a bird’s eye view of the planet and the opportunity to see broad scale structures, the scale of which would be impossible to grasp from the ground. They can, from time to time, much like when you cloud spot, reveal interesting and unexpected features too!

The image above is a processed LANDSAT 7 Satellite image. Stephane Dominguez, a researcher at the University of Montpellier, acquired the image to study the Zagros Fold and thrust belt: the result of the collision of the Iranian Plate and the Arabian Plate.

Whilst studying the image, Stephane noticed an uncanny resemblance…who knew the Zagros mountain belt hosts a velociraptor? Stephane modified the image, using Photoshop, to obtain the false colours which highlight the dinosaur shape in the image. A little thumbnail of a velociraptor is included too, for comparison!

The surface morphology of the image is dominated by EW trending folds, with partially eroded cores. Darker/black areas correspond to salt diapirs that reached the surface in the fold cores or along reverse faults bounding the folds. We’ve featured the Zagros Mountains in our Imaggeo on Monday’s posts recently; you can find more details on the geology of the region here.

Imaggeo is the EGU’s online open access geosciences image repository. All geoscientists (and others) can submit their photographs and videos to this repository and, since it is open access, these images can be used for free by scientists for their presentations or publications, by educators and the general public, and some images can even be used freely for commercial purposes. Photographers also retain full rights of use, as Imaggeo images are licensed and distributed by the EGU under a Creative Commons licence. Submit your photos at


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