GeoLog

Laura Roberts-Artal

Laura Roberts Artal is the Communications Officer at the European Geosciences Union. She is responsible for the management of the Union's social media presence and the EGU blogs, where she writes regularly for the EGU's official blog, GeoLog. She is also the point of contact for early career scientists (ECS) at the EGU Office. Laura has a PhD in palaeomagnetism from the University of Liverpool. Laura tweets at @LauRob85.

Imaggeo on Mondays: Stone Flower

In a true feat of endurance, self-discovery and resilience, Solmaz Mohadjer and Josy Strunden, geology students at the University of Tübingen (Germany), cycled 800 km in the Pamir Mountains as part of a trip to raise awareness about autism in Tajikistan. ““We cycled through one of the most tectonically active regions on the planet, passing by mountain communities that welcomed us warmly as well as ancient fortresses, hermit caves, Buddhist stupas, hot springs, and geologic wonders such as the Stone Flower” describes Solmaz.

Stone Flower. (Credit: Solmaz Mohadjer, via imaggeo.egu.eu)

Stone Flower. (Credit: Solmaz Mohadjer, via imaggeo.egu.eu)

Central Asia is home to the mighty Himalayas, Tian Shan, Karakoram, Kunlun and Hindu Kush mountain ranges. Where these all meet you find the less well known, but no less impressive, Pamir Mountains. The range includes some peaks in excess of 6000m which combined with high undulating grasslands of the eastern portion of the mountains (which in the local language are known as pamirs) means this region has been known as the “Roof of the World” since Victorian times. The precise extent of the mountains is highly debated but the bulk of the range spans the territories of Tajikistan, Afghanistan and Kyrgyzstan.

Much like the Tibet orogen, the Pamir Mountains result from the collision of the Indian and Eurasian Plates 40 to 50 million years ago, during the Eocene, leading to the closing of the Tethys Sea. Similarly to the Tibetan peaks, the Pamir Mountains are characterised by a thick crust (up to 65 km) with an extensive plateau. The high peaks of the Pamirs are the result of up to 2100 km of shortening which is ongoing today as India continues to travel northwards pushing into the Eurasian plate.

Geologically the Pamir Mountains can be divided into three broad zones (or belts) which mainly encompass gneisses of a variety of ages. The southern zone is dominated by ancient Precambrian (more than 540 million years old) metamorphic rocks including marbles and quartzites. Younger limestones, sandstones and shales of Jurassic, Triassic, and Permian ages (about 300 to 145 million years ago) form the central zone. The northern most Pamirs are the most geologically complex and the deformation history is the hardest to unravel given that the force of the collision between the two tectonic plates thrusts old rocks up and over younger ones forming structures known as overthrusts.

This disharmonic fold in our Imaggeo on Mondays photograph, found in the complex northern Pamirs, is the result of the intense squeezing of the rocks as the two tectonic plates converge. It is formed of three layers of rocks with very different properties: a soft layer of limestone and marl is sandwiched between slightly tougher sandstones and conglomerates. This means the rocks do not bend uniformly when squeezed and so form the beautiful structure in the stone flower.

The ongoing movement of the plates means this area is seismically active, registering in excess of 2500 earthquakes a year. Whilst the earthquakes themselves remain the primary hazard in the region, rockfalls triggered by the seismic activity and mudflows, as well asflash floods resulting from severe storms also create a major natural hazard. Solmaz is attempting to quantify and better understand the hazards associated with high mountains, in particular earthquakes and rockfalls, so it is not surprising that she has a keen interest in this part of the world. In addition, she is passionate about educating local communities about regional geohazards and helping them increase their resilience to the adverse effects they can potentially have on everyday life.

Image on left (alluvial fan and Hindu Kush) was taken somewhere along the Wakhan Corridor (Credit: Solmaz Mohadjer, via imaggeo.egu.eu). The image on the right  was taken in a villages called “Yakhshwol” in the Wakhan Corridor (Credit: Solmaz Mohadjer).

Image on left (alluvial fan and Hindu Kush) was taken somewhere along the Wakhan Corridor (Credit: Solmaz Mohadjer, via imaggeo.egu.eu). The image on the right was taken in a villages called “Yakhshwol” in the Wakhan Corridor (Credit: Solmaz Mohadjer).

 

Imaggeo on Mondays: Glarus Alps

Undoubtedly, the Alps are one of the best studied mountain ranges in the world. Appreciating their immense beauty and geological wealth can be difficult from the ground, given their vast scale and the inaccessibility of some of their more challenging peaks. Kurt Stüwe, along with alpine photographer Ruedi Homberger, set about changing this by undertaking the ambitious task of photographing the length of the Alps, from Nice to Vienna, in a small aircraft. The result is a compilation of stunning photographs that capture the magnificence of the Alps and contribute to a better understanding of their geological history.

Glarus Alps. (Credit: Kurt Stüwe, via imaggeo.egu.eu

Glarus Alps. (Credit: Kurt Stüwe, via imaggeo.egu.eu)

The photo shows the Bifertenstock in the Glarus Alps looking east. The region in the middle ground is part of the “Tectonics Arena Sardona“, which is a UNESCO nature world heritage region featuring also the Glarus Thrust – arguably the most famous structure in the Alps. The rocks in the foreground of the picture are part of the Mesozoic (spanning ages between 252 and 66 million years ago) cover sequence that overlies the Variscan gneisses of the Aare Massif in eastern Switzerland. The 300 million year old Variscan gneisses can be seen in the lower reaches of the photograph on both sides of the mountain in the Linth valley (at left) and Rhine valley (at right). The distinctly orange dolomite (sedimentary carbonate rocks) bed separates gneisses from marine sediments.

In much of the Alps, the onset of deposition of Mesozoic sediments onto the Palaeozoic (Variscan) gneisses in the Permian and Triassic was the beginning of a prolonged period of sedimentation that lasted almost 200 million years until the Eocene. The sedimentation was the consequence of slow continuous cooling and thickening of the mantle part of the Adriatic lithosphere following dramatic lithospheric thinning events in the Permian. In the Jurassic this thickening ultimately led to negative buoyancy of the entire continental lithosphere and thus to the onset of intracontinental subduction inside the Adriatic plate. As such, the Mesozoic sedimentation may be viewed as the trigger of the Alpine orogenic cycle. In other parts of the Swiss Alps, these sediments were late sheared off their own basement and transported north forming the famous Helvetic nappes of Switzerland.

The photo was taken as part of a multiyear project in which the entire Alpine chain was photographed from a geological perspective from a two seated Piper Supercub aircraft. The present photo was taken on a late afternoon while returning from a photo flight in the Bernese Oberland back to Arosa. You can see more photos from the project on the project website.

Helvetic Nappes of Switzerland. (Credit: Kurt Stüwe, via imaggeo.egu.eu)

Helvetic Nappes of Switzerland. (Credit: Kurt Stüwe, via imaggeo.egu.eu)

 

By Prof. Dr. Kurt Stüwe, Earth Sciences Department, Graz University, Austria.

Reference

Schster, R. & Stüwe, K., Permian metamorphic event in the Alps, Geology, 36,8, 603-606, 2008

 

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.

Why choose a PICO session at EGU 2015?

Why choose a PICO session at EGU 2015?

Some of the sessions scheduled for the upcoming EGU General Assembly are PICO only sessions. This means that, rather than being oral or poster format, they involve Presenting Interactive COntent (PICO). The aim of these presentations is to highlight the essence of a particular research area – just enough to get the audience excited about a topic without overloading them with information.

PICO sessions start with a series of 2 minute long presentations – one from each author. They can be a Power Point, a movie, an animation, or simply a PDF showing your research on a display. After the 2 minute talks, the audience can explore each presentation on touch screens, where authors are also available to answer questions and discuss their research in more detail.

This format combines the best of oral and poster presentations, allowing researchers to stand up be recognised for great research by making an oral contribution as well as discuss their work in detail and network with other participants. This year we are also making a few improvements to the layout of the PICO presentation areas in the large halls to minimise noise disruption to presenters.

See the General Assembly website for more information about PICO. You can also check out the short introductory video below:

Imaggeo on Mondays: Gothic Snow Architecture.

Whilst on a family holiday in Norway, Gerrit de Rooij took this incredible photograph of an ice arch. Understandably geoscience is not his top priority whilst taking photographs on holiday, however Gerrit points out that pretty much every picture of a landscape has hydrology in there somewhere”, as he goes on to describe below.

This picture was taken near Balestrand, a village along the Sognefjord in Norway (Norway’s largest fjord and the second largest in the world!). The altitude was approximately 900 m above sea level (asl), and not always does all snow vanish during summer over there (we were there in August 2013). What you can see in the picture are the remnants of a much thicker snow pack that covered the stream that trickles down. On the right hand side you can see a glimpse of the other side of the arch that  must have gradually been carved out by the stream during the snow melt season (as they call spring over there). Once a tunnel was carved out, thaw took over. The black lines of rock dust on the ridges of the snow arch presumably were left behind by water streaming down along them from the top of the melting snow cover. In the top rim the source of this material is still visible.

Gothic Snow Architecture. (Credit: Gerrit de Rooij via imaggeo.egu.eu)

Gothic Snow Architecture. (Credit: Gerrit de Rooij via imaggeo.egu.eu)

Exposed are ancient rocks, heavily eroded by several glaciations and subsequent Holocene freeze-thaw cycles and snow melt flows. The location of the picture is on the west side of Norway’s mountain range. These mountains force western winds from the Atlantic upward, which makes the air cool down and release a lot of its moisture. The very frequent rains (we had 3 rain free days out of 16) create lush vegetation at lower altitudes (the tree line is between 600 and 700 m asl) and sustain extensive moss carpets higher up, as visible in the image. In places where the rock face is too steep to support moss, lichen covers it, which is evidence of very clean air – lichen are highly sensitive to air pollution.

The stream (and many similar streams nearby) feed a small lake that supplies Balestrand with drinking water. The lake can be reached in a day from Balestrand, but hiking further requires an overnight stay, even for most Norwegians, rugged as they may be. There are no huts or any other facilities, so you need to carry your camping gear with you. We camped a little higher without seeing anybody, and from the condition of the trails it was clear that everything beyond the reach of a day trip was used very infrequently. This unperturbed state, the abundant precipitation, and the inertious rocks made the water of the lake crystal clear (several meters of visibility) and very poor in nutrients (hardly any underwater vegetation), making it an excellent source of local drinking water.

In the composition, I liked the two halves of the snow arch mirroring each other, and the fact that the lines and the slope of the large exposed rock face are similar to those in the larger snow arch. The bright green of the moss upslope adds liveliness and draws the eye. I have a relatively simple camera (you want something light when backpacking) and at the time had no software to manipulate my pictures so I had to choose my viewpoint carefully and work with the light that was there. I scooped and stood very close to the snow to create a sense of perspective and have the arch reach over the camera.

By Gerrit de Rooij, Helmholtz Centre for Environmental Research – UFZ, Halle (Saale), Germany

 

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.

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